M2 tumor‑associated macrophages promote tumor progression in non‑small‑cell lung cancer

  • Authors:
    • Ryota Sumitomo
    • Tatsuya Hirai
    • Masaaki Fujita
    • Hiroaki Murakami
    • Yosuke Otake
    • Cheng‑Long Huang
  • View Affiliations

  • Published online on: September 30, 2019     https://doi.org/10.3892/etm.2019.8068
  • Pages: 4490-4498
  • Copyright: © Sumitomo et al. This is an open access article distributed under the terms of Creative Commons Attribution License.

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Abstract

Tumor‑associated macrophages (TAMs) are key components of the tumor microenvironment that can be polarized into different phenotypes, including tumor‑inhibiting M1 macrophages and tumor‑promoting M2 macrophages. To elucidate the biological and clinical significance of M2 TAMs in non‑small‑cell lung cancer (NSCLC), a comprehensive clinical assessment of the tissue distribution of M2 TAMs was performed. The tissue distribution of M2 TAMs was retrospectively analyzed using CD163 immunohistochemistry in 160 consecutive patients who underwent NSCLC resection. Tumor proliferation was evaluated via the Ki‑67 proliferation index. The results revealed that the stromal density of M2 TAMs was significantly associated with the C‑reactive protein (CRP) level (P=0.0250), the Ki‑67 proliferation index (P=0.0090) and invasive size (P=0.0285). Furthermore, the stromal M2 TAM density was significantly associated with tumor differentiation (P=0.0018), lymph node metastasis (P=0.0347) and pathological stage (P=0.0412). The alveolar M2 TAM density was also significantly associated with the CRP level (P=0.0309), invasive size (P<0.0001), tumor differentiation (P=0.0192), tumor status (P=0.0108) and pathological stage (P=0.0110). By contrast, no association was observed between islet M2 TAM density and the aforementioned biological and clinical factors. In regards to prognosis, disease‑free survival rate was significantly lower in patients with stromal M2 TAM‑high tumors (P=0.0270) and in those with alveolar M2 TAM‑high tumors (P=0.0283). Furthermore, the overall survival rate was also significantly lower in patients with stromal M2 TAM‑high tumors (P=0.0162) and in those with alveolar M2 TAM‑high tumors (P=0.0225). Therefore, during NSCLC progression, M2 TAMs may induce tumor cell aggressiveness and proliferation and increase metastatic potential, resulting in a poor prognosis in patients with NSCLC.

Introduction

Lung cancer is the leading cause of cancer-related mortality in developed countries (1,2). Based on the treatment strategy, lung cancer is clinically classified into non-small-cell lung cancer (NSCLC) and small-cell lung cancer. NSCLC accounts for 85% of all lung cancer cases, and it includes several types of histological subtypes, including adenocarcinoma and squamous cell carcinoma. Due to the advances in molecular biology, several molecular-targeted therapies have been developed for lung adenocarcinomas. Epidermal growth factor receptor (EGFR)-tyrosine kinase inhibitors (TKIs), such as gefitinib, have been proven to be effective against lung adenocarcinomas with activating EGFR mutations (3). Anaplastic lymphoma kinase (ALK) inhibitors, such as alectinib, have also been reported to be effective against lung adenocarcinomas with the ALK fusion gene (4). However, molecular-targeted therapies are not applicable to cancers without mutations of these target genes. Recently, immune checkpoint inhibitors (ICIs), such as nivolumab, have been demonstrated to exhibit prominent clinical efficacy against various types of cancer, including NSCLC (5). However, these ICIs have been reported to be less effective against patients with programmed death-ligand 1 (PD-L1)-negative tumors (6). Therefore, it is crucial to fully elucidate tumor biology in order to develop novel treatment strategies against NSCLC without these mutations of target genes or PD-L1-positive expression.

The evaluation of infiltrating macrophages in tumors, referred to as tumor-associated macrophages (TAMs), has been reported to be important. TAMs are key components of the tumor microenvironment (TME) that influence tumor growth and progression (7,8). Tumor cells release various chemokines to attract macrophages, as well as other inflammatory cells, into the tumor stroma, and a number of substances secreted by TAMs may stimulate the proliferation and metastasis of tumor cells (9,10). Several clinical studies on TAMs have been reported in various human cancers, including NSCLC, colon and breast cancer (1114). However, previous studies using only immunostaining for CD68, the most common pan-macrophage marker, yielded confusing results regarding its prognostic potential in NSCLC. For example, these studies reported that increased levels of TAMs in tumor islets were associated with good prognosis (1519), whereas the increased levels of TAMs in the tumor stroma were found to be associated with poor prognosis (15,18). There could be several factors responsible for such confusing results.

First, macrophages are particularly heterogeneous in their phenotype and function. Under physiological or pathological conditions, macrophages can be polarized into different phenotypes, namely tumor-inhibiting M1 and tumor-promoting M2 macrophages (11,20,21). M1 TAM-derived cytokines have the ability to kill pathogens. On the other hand, M2 macrophages are pro-angiogenic and participate in wound healing by downregulating inflammatory response to promote connective tissue remodeling (14). Th2-derived cytokines, such as interleukin (IL)4, IL10 and IL13, transforming growth factor-β, prostaglandin E2 or colony-stimulating factor 1, may promote M2 differentiation of macrophages (8,21). During tumor progression, these signals originating from tumor and stromal cells may induce the production of M2 TAMs in the TME. M2 TAMs may induce angiogenesis by secretion of cytokines, such as vascular endothelial growth factor (VEGF) (22), and promote tumor growth and metastasis. Experimental studies also demonstrated that M2 macrophages may promote tumor cell proliferation (23).

Second, macrophages are distributed in various tissue compartments in lung cancer, such as tumor stroma, tumor islets and alveolar space, and the TAMs present in different tissue components may display different biological properties (11,12). In fact, previous clinical studies in NSCLC demonstrated that high infiltration of tumor islets by M1 TAMs was associated with increased survival (20,24), whereas infiltration of tumor islets and tumor stroma by high numbers of M2 TAMs was associated with reduced survival (20,25). In addition, the levels of M2 macrophages were reported to be higher compared with those of M1 macrophages in NSCLC (24).

Taking these factors into consideration, in order to elucidate the biological and clinical significance of M2 TAMs in NSCLC, a comprehensive clinical study on M2 TAMs in terms of tissue distribution was performed, using immunostaining for CD163, an M2 macrophage marker (20,24,25).

Materials and methods

Patients

A total of 160 consecutive NSCLC patients who underwent surgery at the Department of Thoracic Surgery of Kitano Hospital between November 2011 and October 2014 were retrospectively investigated. The study protocol was approved by the Institutional Ethics Committee of Kitano Hospital (P181200300), and written informed consent was obtained from all the patients. Pathological staging was determined using the 8th tumor-node-metastasis (TNM) classification system (26). Invasive size was defined as the maximum dimension of the invasive component, excluding the lepidic growth component (26). The histological type and grade of differentiation of the tumors were determined according to the World Health Organization classification system (27). The patients' medical records and histopathological diagnoses were fully documented. The patient records included follow-up data as of August 2018. The overall median follow-up period was 42.8 months.

Immunohistochemistry

Immunohistochemical studies were performed to evaluate the M2 TAM distribution by CD163 staining and the tumor proliferation rate by Ki-67 proliferation index, using the Ventana BenchMark GX system (Roche/Ventana Medical Systems), according to the recommended protocol. The following antibodies were used: Mouse monoclonal anti-human CD163 antibody (clone 760-4437, Roche/VentanaMedical Systems), and rabbit monoclonal anti-human Ki-67 antibody (clone 30-9, Roche/VentanaMedical Systems). Formalin-fixed paraffin-embedded tissues were cut into 4-µm sections and mounted on poly-L-lysine-coated slides. The sections were deparaffinized and rehydrated, and antigen retrieval was performed with Cell Conditioner 1 (32 min for CD163 and 64 min for Ki-67). The sections were then incubated with the specific primary antibody against CD163 (16 min) and Ki-67 (8 min). Subsequently, the sections were treated with the OptiView HQ Linker for 8 min and the OptiView HRP Multimer for 8 min. Finally, counterstaining was performed with Mayer's hematoxylin and Scott's tap water bluing reagent.

Evaluation of immunohistochemistry

Evaluation of stained tissue sections was performed by two investigators (RS and TH) who were blinded to the patients' clinical status. Cases with discrepancies were jointly re-evaluated and a consensus was reached. For CD163 staining, the five most representative high-power fields (magnification, ×400; 0.0625 mm2) of the tumor stroma, tumor islets and alveolar space per tissue section were selected (Fig. 1). Tumor stroma was defined as the area where tumor stromal cells accounted for >70% of the total cells (28). In adenocarcinoma in situ cases with a scant stromal component, the perivascular or peribronchiolar stromal tissue inside the tumor was analyzed as tumor stroma. Tumor islets were defined as areas where tumor cells accounted for >70% of the total cells. The alveolar space was defined as the air space inside the main tumor or outside within three alveoli. The number of CD163-positive cells in each area was counted manually, and the mean number of fields in each area was calculated. Finally, the CD163-positive macrophage (M2 TAM) density was defined as cell number per mm2 in the tumor stroma (stromal M2 TAM), tumor islets (islet M2 TAM) and alveolar space (alveolar M2 TAM). The percentage of carcinoma cells with a positive staining for Ki-67 in a given specimen was defined as the Ki-67 proliferation index (29).

Statistical analysis

As stromal M2 TAM density (P=0.1648), islet M2 TAM density (P=0.2845), alveolar M2 TAM density (P=0.1936), C-reactive protein (CRP) level (P=0.3056), total tumor size (P=0.1387), invasive size (P=0.1211) and Ki-67 proliferation index (P=0.1734) exhibited normal distribution (Kolmogorov-Smirnov analysis), statistical significance was assessed by the t-test, ANOVA with Bonferroni/Dunn test or Pearson's correlation coefficient. Categorical variables were compared using χ2 test. As previous clinical studies reported that the level of CRP, a marker of inflammatory response, was related to cancer risk and prognosis (30,31), receiver operating characteristic (ROC) curve analysis was performed to determine the optimal cut-off value of each M2 TAM density with maximal sensitivity and specificity for distinguishing between <1 mg/l and ≥1 mg/l of CRP (30,31). The sample was classified as stromal M2 TAM-high when the stromal M2 TAM density was >380 [area under the curve (AUC)=0.521]. The sample was classified as alveolar M2 TAM-high when the alveolar M2 TAM density was >400 (AUC=0.628). On the other hand, the sample was classified as islet M2 TAM-high when the islet M2 TAM density was >35, its median value, because the islet M2 TAM density was not associated with the CRP level. Disease-free survival (DFS) was defined as the time from treatment initiation (surgical resection, chemotherapy or radiation) to the date of disease recurrence or death from any cause. Overall survival (OS) was defined as the time from treatment initiation to the date of death from any cause. The Kaplan-Meier method was used to estimate the probability of DFS and OS as a function of time, and differences in the survival of subgroups of patients were compared using Mantel's log-rank test. The univariate analysis using the Cox regression model was used to evaluate the effects on survival. P-values obtained used a t-test, Mantel's log-rank test or Bonferroni/Dunn post-hoc test were based on the two-sided statistical analysis, and a P<0.05 was considered to indicate a statistically significant difference.

Results

Distribution of M2 TAMs in the tumor stroma, tumor islets and alveolar space

The stromal M2 TAM density varied greatly among the 160 tumor tissues investigated (mean, 407.0±389.2). A total of 93 tumors (58.1%) were classified as stromal M2 TAM-low tumors, and 67 (41.9%) as stromal M2 TAM-high tumors. In addition, the islet M2 TAM density also varied greatly among the 160 tumor tissues (mean, 82.3±143.4). A total of 80 tumors (50.0%) were islet M2 TAM-low tumors, and 80 (50.0%) were islet M2 TAM-high tumors. The stromal M2 TAM density was moderately correlated with the islet M2 TAM density (r=0.412; Fig. 2A). However, the islet M2 TAM density was significantly lower compared with the stromal M2 TAM density in each tumor tissue (P<0.001).

The alveolar M2 TAM density also varied greatly among the 160 tumor tissues (mean, 560.6±612.9). A total of 88 tumors (55.0%) were alveolar M2 TAM-low tumors, and 72 (45.0%) were alveolar M2 TAM-high tumors. The alveolar M2 TAM density was also moderately correlated with the stromal M2 TAM density (r=0.438; Fig. 2B). However, the correlation between the islet M2 TAM density and the alveolar M2 TAM density was low (r=0.212).

Biological and clinical significance of M2 TAMs in the tumor stroma among resected NSCLC

The biological significance of the M2 TAMs in the tumor stroma is shown in Fig. 3. The CRP level was significantly higher in the stromal M2 TAM-high group compared with that in the stromal M2 TAM-low group (4.41±7.88 vs. 2.29±3.52 mg/l, P=0.0250; Fig. 3A). In addition, the Ki-67 proliferation index was significantly higher in the stromal M2 TAM-high group compared with that in the stromal M2 TAM-low group (34.8±30.0 vs. 23.2±25.1%, P=0.0090; Fig. 3B). The invasive size was also significantly higher in the stromal M2 TAM-high group compared with that in the stromal M2 TAM-low group (28.3±15.9 vs. 23.0±14.6 mm, P=0.0285; Fig. 3C).

The distribution of the stromal M2 TAM density according to clinicopathological characteristics is shown in Table I. With respect to tumor histology, the stromal M2 TAM density was significantly higher in squamous cell carcinomas compared with that in adenocarcinomas (P=0.0034). In addition, the stromal M2 TAM density was significantly associated with tumor differentiation (P=0.0018), and was significantly higher in poorly differentiated tumors compared with that in well-differentiated and moderately differentiated tumors (P=0.0004 and P=0.0149, respectively). With respect to nodal status, the stromal M2 TAM density was significantly higher in node-positive tumors compared with that in node-negative tumors (P=0.0347). Furthermore, the stromal M2 TAM density was significantly associated with pathological stage (P=0.0412).

Table I.

Distribution of M2 tumor-associated macrophage density in patients with NSCLC according to clinicopathological characteristics.

Table I.

Distribution of M2 tumor-associated macrophage density in patients with NSCLC according to clinicopathological characteristics.

CharacteristicsnTumor stroma (cells/mm2)P-valueTumor islet (cells/mm2)P-valueAlveolar space (cells/mm2)P-value
Smoking
  Non-smoker85370.6±367.40.2092a76.6±102.20.5960a525.1±684.30.4374a
  Smoker75448.2±411.0 88.7±179.7 600.8±522.1
Tumor status
  T08207.0±330.10.1726b52.2±52.10.0714b239.0±168.30.0108b
  T172379.7±386.6 56.8±67.7 442.9±625.8
  T2-480451.6±392.6 108.3±188.9 698.7±599.4
Nodal status
  N0123371.4±344.90.0347a74.1±106.70.1864a517.1±575.00.1017a
  N1-337525.2±497.1 109.7±226.5 705.2±714.8
Pathological Stage
  0795.4±104.60.0412b43.8±50.10.8020b241.1±181.70.0110b
  I100385.3±359.4 89.1±166.9 472.2±594.7
  II24548.0±428.9 66.9±83.5 851.3±657.4
  III29440.3±453.5 80.9±106.4 701.9±611.6
Differentiation
  Well33251.8±278.70.0018b80.4±123.20.0522b405.9±393.60.0192b
  Moderately93397.7±369.4 59.2±68.5 526.1±561.4
  Poorly34499.9±154.0 147.3±255.9 805.1±832.0
Histology
  Adenocarcinoma128357.3±365.50.0034b71.8±95.10.0692b535.6±637.20.3053b
  Squamous cell carcinoma25635.3±469.4 106.0±261.9 726.4±534.0
  Large cell carcinoma7499.9±154.0 190.0±247.6 424.9±266.8
Total number of patients160407.0±389.2 82.3±143.4 560.6±612.9

a P-value determined using a t-test.

b P-value determined using ANOVA followed by a Bonferroni/Dunn test. NSCLC, non-small-cell lung cancer.

Biological and clinical significance of M2 TAMs in the tumor islets among resected NSCLC

The islet M2 TAM was not associated with the CRP level, the Ki-67 proliferation index or the invasive size (Fig. 3D-F). In addition, the islet M2 TAM density was not associated with tumor histology, tumor differentiation, tumor status, nodal status or pathological stage (Table I).

Biological and clinical significance of M2 TAMs in the alveolar space among resected NSCLC

With respect to biological significance, the CRP level was significantly higher in the alveolar M2 TAM-high group compared with that in the alveolar M2 TAM-low group (4.29±6.64 vs. 2.27±4.93 mg/l, P=0.0309; Fig. 3G). On the other hand, the alveolar M2 TAM was not significantly associated with the Ki-67 proliferation index (Fig. 3H). However, the total tumor size was significantly higher in the alveolar M2 TAM-high group compared with that in the alveolar M2 TAM-low group (31.7±14.8 vs. 23.4±12.8 mm, P=0.0005). In addition, the invasive size was also significantly higher in the alveolar M2 TAM-high group compared with that in the alveolar M2 TAM-low group (30.5±15.5 vs. 20.9±13.9 mm, P<0.0001; Fig. 3I).

With respect to clinical significance, the alveolar M2 TAM density was significantly associated with tumor differentiation (P=0.0192) (Table I), and the alveolar M2 TAM density was significantly higher in poorly differentiated tumors compared with that in well-differentiated and moderately differentiated tumors (P=0.0073 and P=0.0219, respectively). In addition, the alveolar M2 TAM density was significantly associated with tumor status and pathological stage (P=0.0108 and P=0.0110, respectively).

DFS of patients with resected NSCLC in relation to M2 TAM status

With respect to the stromal M2 TAM status, the 5-year DFS rate was significantly lower in patients with stromal M2 TAM-high tumors compared with stromal M2 TAM-low tumors (54.7 vs. 72.9%, P=0.0270; Fig. 4A). In particular, among patients with early-stage disease (stage 0 and I), the 5-year DFS rate was significantly lower in patients with stromal M2 TAM-high tumors compared with those with stromal M2 TAM-low tumors (64.0 vs. 84.5%, P=0.0233; Fig. 4B). However, among patients with advanced disease (stage II and III), no significant difference was observed in the DFS of patients with resected NSCLC patients in relation to the stromal M2 TAM status (Fig. 4C). In addition, no difference was observed in the DFS of patients with resected NSCLC according to islet M2 TAM status (Fig. 4D). With respect to the alveolar M2 TAM status, the 5-year DFS rate was significantly lower in patients with alveolar M2 TAM-high tumors compared with those with alveolar M2 TAM-low tumors (54.0 vs. 76.2%, P=0.0283; Fig. 4E). However, among patients with early-stage disease (stage 0 and I), no significant difference was observed in the DFS of patients with resected NSCLC patients in relation to the alveolar M2 TAM status (Fig. 4F). Univariate analyses using the Cox regression model also demonstrated that the stromal M2 TAM status [HR=1.869 (95% CI: 1.064–3.283); P=0.0296] and the alveolar M2 TAM status [HR=1.873 (95% CI: 1.059–3.311); P=0.0310] were significant factors for predicting the DFS of patients with resected NSCLC.

OS of patients with resected NSCLC in relation to M2 TAM status

With respect to the stromal M2 TAM status, the 5-year OS rate was significantly lower in patients with stromal M2 TAM-high tumors compared with those with stromal M2 TAM-low tumors (74.5 vs. 85.8%, P=0.0162; Fig. 5A). In particular, for early-stage disease (stage 0 and I), the 3-year OS was significantly lower in patients with stromal M2 TAM-high tumors compared with those with stromal M2 TAM-low tumors (87.3 vs. 98.5%, P=0.0204; Fig. 5B). However, for advanced disease (stage II and III), no difference was observed in the OS of patients with resected NSCLC in relation to the stromal M2 TAM status (Fig. 5C). In addition, no difference was observed in the OS of patients with resected NSCLC according to islet M2 TAM status (Fig. 5D). With respect to the alveolar M2 TAM status, the 5-year OS was significantly lower in patients with alveolar M2 TAM-high tumors compared with those with alveolar M2 TAM-low tumors (72.7 vs. 89.5%, P=0.0225; Fig. 5E). However, among patients with early-stage disease (stage 0 and I), no significant difference was observed in the OS of patients with resected NSCLC patients in relation to the alveolar M2 TAM status (Fig. 5F). Univariate analyses using the Cox regression model also demonstrated that the stromal M2 TAM status [HR=2.630 (95% CI: 1.160–5.964); P=0.0207] and the alveolar M2 TAM status [HR=2.573 (95% CI: 1.109–5.972); P=0.0278] were significant factors for predicting OS in patients with resected NSCLC.

Discussion

In order to elucidate the biological and clinical significance of M2 TAMs in NSCLC, a comprehensive clinical study on M2 TAMs with respect to tissue distribution was performed. Regarding M2 macrophage markers, such as CD163 and CD204 (28), CD163 immunostaining was used, as previous clinical studies using this immunostaining demonstrated the clinical significance of M2 TAMs in NSCLC patients (20,24,25). The findings of the present study demonstrated that the stromal M2 TAM density in NSCLC was associated with tumor differentiation, CRP level, tumor growth, invasive size, lymph node metastasis, pathological stage and poor prognosis. In addition, the alveolar M2 TAM density was also associated with tumor differentiation, CRP level, tumor status, invasive size, pathological stage and poor prognosis. By contrast, the islet TAM density was significantly lower compared with the stromal M2 TAM density, and no association was observed between the islet M2 TAM and the abovementioned biological and clinical factors.

First, TAMs originate from circulating blood cells, such as monocytes. Chemotactic signals originating from tumor or stromal cells in the TME could recruit monocytic precursors to the tumor site. The present study demonstrated that the CRP level was associated with both the stromal and alveolar M2 TAM density. A previous clinical study also reported that a higher density of CD163-positive macrophages was associated with elevated CRP levels (32). These results suggest the existence of crosstalk between cancer-related inflammation and M2 TAMs in TME (8). During tumor progression, this crosstalk may generate more aggressive tumors. In fact, previous clinical studies reported that an elevated CRP level was a poor prognostic factor in NSCLC patients (33,34).

Next, the present study demonstrated that the stromal M2 TAM density was associated with tumor proliferation and invasive size, and that the alveolar M2 TAM density was also associated with invasive size. M2 TAMs produce various tumor-promoting cytokines, including VEGF, which affect tumor growth and metastasis (8,21). In addition, invasive size was found to be correlated with various prognostic pathological factors (35), and it is an important factor for TNM classification (26). To the best of our knowledge, the present study was the first to demonstrate that stromal M2 TAM density is correlated with tumor proliferation and invasive size, which indicate a more aggressive malignant potential.

Therefore, the present study revealed that the stromal M2 TAM density is associated with lymph node metastasis, pathological stage, reduced DFS and reduced OS. The alveolar M2 TAM density was also associated with reduced DFS and reduced OS. Previous clinical studies also reported that stromal M2 macrophages are associated with poor prognosis in lung cancer patients (20,25,36). Former clinical studies using immunostaining for only CD68 also demonstrated that the stromal macrophages, which were primarily M2 TAMs, were associated with a poor prognosis in NSCLC (15,18). Although the prognostic significance of M2 TAMs was found only on univariate analysis using the Cox regression model in the present study, the statistical analyses regarding prognosis did not reach statistical significance on multivariate analysis using the Cox regression model. These results may be partly due to the relatively small number of patients, which was a limitation of the present study. Further clinical studies using a higher number of patients are required.

Considering the results of the present study, during NSCLC progression, TME may produce M2 TAMs, thereby promoting tumor aggressiveness. M2 TAMs are predominantly located in the tumor stroma, and may move into the alveolar space. The stromal M2 TAM density is a potential marker for predicting malignant potential and clinical outcome. Therefore, postoperative adjuvant chemotherapy may be required for patients with stromal M2 TAM-high tumors, even in the early stages. In addition, further investigation on TAMs may enable the development of novel treatments, such as TAM repolarization strategies using ‘M2-to-M1’ macrophage reprogramming molecules (8,21).

Acknowledgements

Not applicable.

Funding

No funding was received.

Availability of data and materials

The datasets used and/or analyzed during the present study are available from the corresponding author on reasonable request.

Authors' contributions

RS, MF and CH designed the present study. RS, TH and CH designed and performed the experiments. RS, HM and YO collected the data. RS, HM, CH and YO analyzed and interpreted the data and wrote the manuscript. All authors have read and approved the final version of the manuscript for publication.

Ethics approval and consent to participate

The current study was approved by the Institutional Ethics Committee of the Kitano Hospital (approval no. P181200300), and written informed consent was obtained from each patient. The research was conducted in compliance with the principles outlined in the Declaration of Helsinki.

Patient consent for publication

Written informed consent for publication of patient data/accompanying images was obtained.

Competing interests

The authors declare that they have no competing interests.

References

1 

Bray F, Ferlay J, Soerjomataram I, Siegel RL, Torre LA and Jemal A: Global cancer statistics 2018: GLOBOCAN estimates of incidence and mortality worldwide for 36 cancers in 185 countries. CA Cancer J Clin. 68:394–424. 2018. View Article : Google Scholar : PubMed/NCBI

2 

Siegel RL, Miller KD and Jemal A: Cancer statistics, 2019. CA Cancer J Clin. 69:7–34. 2019. View Article : Google Scholar : PubMed/NCBI

3 

Hsu WH, Yang JC, Mok TS and Loong HH: Overview of current systemic management of EGFR-mutant NSCLC. Ann Oncol. 29 (Suppl_1):i3–i9. 2018. View Article : Google Scholar : PubMed/NCBI

4 

Fan J, Fong T, Xia Z, Zhang J and Luo P: The efficacy and safety of ALK inhibitors in the treatment of ALK-positive non-small cell lung cancer: A network meta-analysis. Cancer Med. 7:4993–5005. 2018. View Article : Google Scholar : PubMed/NCBI

5 

Borghaei H, Paz-Ares L, Horn L, Spigel DR, Steins M, Ready NE, Chow LQ, Vokes EE, Felip E, Holgado E, et al: Nivolumab versus docetaxel in advanced nonsquamous non-small-cell lung cancer. N Engl J Med. 373:1627–1639. 2015. View Article : Google Scholar : PubMed/NCBI

6 

Garon EB, Rizvi NA, Hui R, Leighl N, Balmanoukian AS, Eder JP, Patnaik A, Aggarwal C, Gubens M, Horn L, et al: Pembrolizumab for the treatment of non-small-cell lung cancer. N Engl J Med. 372:2018–2028. 2015. View Article : Google Scholar : PubMed/NCBI

7 

Pollard JW: Tumour-educated macrophages promote tumour progression and metastasis. Nat Rev Cancer. 4:71–78. 2004. View Article : Google Scholar : PubMed/NCBI

8 

Mantovani A, Marchesl F, Malesci A, Laghi L and Allavena P: Tumor-associated macrophages as treatment targets in oncololy. Nat Rev Clin Oncol. 14:399–416. 2017. View Article : Google Scholar : PubMed/NCBI

9 

Lewis CE and Pollard JW: Distinct role of macrophages in different tumor microenvironments. Cancer Res. 66:605–612. 2006. View Article : Google Scholar : PubMed/NCBI

10 

Astekar M, Metqud R, Sharma A and Soni A: Hidden keys in stroma: Unlocking the tumor progression. J Oral Macxilofac Pathol. 17:82–88. 2013. View Article : Google Scholar

11 

Mei J, Xiao Z, Guo C, Pu Q, Ma L, Liu C, Lin F, Liao H, You Z and Liu L: Prognostic impact of tumor-associated macrophage infiltration in non-small cell lung cancer: A systemic review and meta-analysis. Oncotarget. 7:34217–34228. 2016. View Article : Google Scholar : PubMed/NCBI

12 

Wu P, Wu D, Zhao L, Huang L, Chen G, Shen G, Huang J and Chai Y: Inverse role of distinct subsets and distribution of macrophage in lung cancer prognosis: A meta-analysis. Oncotarget. 7:40451–40460. 2016.PubMed/NCBI

13 

Ong SM, Tan YC, Beretta O, Jiang D, Yeap WH, Tai JJ, Wong WC, Yang H, Schwarz H, Lim KH, et al: Macrophages in human colorectal cancer are pro-inflammatory and prime T cells towards an anti-tumour type-1 inflammatory response. Eur J Immunol. 42:89–100. 2012. View Article : Google Scholar : PubMed/NCBI

14 

Medrek C, Ponten F, Jirstrom K and Leandersson K: The presence of tumor associated macrophages in tumor stroma as a prognostic marker for breast cancer patients. BMC Cancer. 12:3062012. View Article : Google Scholar : PubMed/NCBI

15 

Welsh TJ, Green RH, Richardson D, Waller DA, O'Byrne KJ and Bradding P: Macrophage and mast-cell invasion of tumor cell islets confers a marked survival advantage in non-small-cell lung cancer. J Clin Oncol. 23:8959–8967. 2005. View Article : Google Scholar : PubMed/NCBI

16 

Kim DW, Min HS, Lee KH, Kim YJ, Oh DY, Jeon YK, Lee SH, Im SA, Chung DH, Kim YT, et al: High tumour islet macrophage infiltration correlates with improved patient survival but not with EGFR mutations, gene copy number or protein expression in resected non-small cell lung cancer. Br J Cancer. 98:1118–1124. 2008. View Article : Google Scholar : PubMed/NCBI

17 

Kawai O, Ishii G, Kubota K, Murata Y, Naito Y, Mizuno T, Aokage K, Saijo N, Nishiwaki Y, Gemma A, et al: Predominant infiltration of macrophages and CD8(+) T cells in cancer nests is a significant predictor of survival in stage IV nonsmall cell lung cancer. Cancer. 113:1387–1395. 2008. View Article : Google Scholar : PubMed/NCBI

18 

Dai F, Liu L, Che G, Yu N, Pu Q, Zhang S, Ma J, Ma L and You Z: The number and microlocalization of tumor-associated immune cells are associated with patient's survival time in non-small cell lung cancer. BMC Cancer. 10:2202010. View Article : Google Scholar : PubMed/NCBI

19 

Feng PH, Yu CT, Wu CY, Lee MJ, Lee WH, Wang LS, Lin SM, Fu JF, Lee KY and Yen TH: Tumor-associated macrophages in stage IIIA pN2 non-small cell lung cancer after neoadjuvant chemotherapy and surgery. Am J Trans Res. 6:593–603. 2014.

20 

Jackute J, Zemaitis M, Pranys D, Sitkauskiene B, Miliauskas S, Vaitkiene S and Sakalauskas R: Distribution of M1 and M2 macrophages in tumor islets and stroma in relation to prognosis of non-small cell lung cancer. BMC Immunol. 19:32018. View Article : Google Scholar : PubMed/NCBI

21 

van Dalen FJ, van Stevendaal MHME, Fennemann FL, Verdoes M and Ilina O: Molecular repolarisation of tumour-associated macrophages. Molecules. 24:E92018. View Article : Google Scholar : PubMed/NCBI

22 

Chen JJ, Yao PL, Yuan A, Hong TM, Shun CT, Kuo ML, Lee YC and Yang PC: Up-regulation of tumor interleukin-8 expression by infiltrating macrophages: Its correlation with tumor angiogenesis and patient survival in non-small cell lung cancer. Clin Cancer Res. 9:729–737. 2003.PubMed/NCBI

23 

Mantovani A, Sozzani S, Locati M, Allavena P and Sica A: Macrophage polarization: Tumor-associated macrophages as a paradigm for polarized M2 mononuclear phagocytes. Trends Immunol. 23:549–555. 2002. View Article : Google Scholar : PubMed/NCBI

24 

Ma J, Liu L, Che G, Yu N, Dai F and You Z: The M1 form of tumor-associated macrophages in non-small cell lung cancer is positively associated with survival time. BMC Cancer. 10:1122010. View Article : Google Scholar : PubMed/NCBI

25 

Chung FT, Lee KY, Wang CW, Heh CC, Chan YF, Chen HW, Kuo CH, Feng PH, Lin TY, Wang CH, et al: Tumor-associated macrophages correlate with response to epidermal growth factor receptor-tyrosine kinase inhibitors in advanced non-small cell lung cancer. Int J Cancer. 131:E227–E235. 2012. View Article : Google Scholar : PubMed/NCBI

26 

Amin MB, Edge S and Greene F: AJCC Cancer Staging Manual8th. Springer; New York, NY, USA: 2017

27 

Travis WD, Brambilla E, Burke AP, Marx A and Nicholson AG: WHO Classification of Tumours of the Lung, Pleura, Thymus and Heart4th. International Agency for Research on Cancer; Lyon, France: 2015

28 

Li Z, Maeda D, Yoshida M, Umakoshi M, Nanjo H, Shiraishi K, Saito M, Kohno T, Konno H, Saito H, et al: The intratumoral distribution influences the prognostic impact of CD68- and CD204-positive macrophages in non-small cell lung cancer. Lung Cancer. 123:127–135. 2018. View Article : Google Scholar : PubMed/NCBI

29 

Scagliotti GV, Micela M, Gubetta L, Leonardo E, Cappia S, Borasio P and Pozzi E: Prognostic significance of Ki67 labelling in resected non small cell lung cancer. Eur J Cancer 29A. 363–365. 1993. View Article : Google Scholar

30 

Siemes C, Visser LE, Coebergh JW, Splinter TA, Witteman JC, Uitterlinden AG, Hofman A, Pols HA and Stricker BH: C-reactive protein levels, variation in the C-reactive protein gene, and cancer risk: The Rotterdam Study. J Clin Oncol. 24:5216–5222. 2006. View Article : Google Scholar : PubMed/NCBI

31 

Allin KH, Bojesen SE and Nordestgaard BG: Baseline C-reactive protein is associated with incident cancer and survival in patients with cancer. J Clin Oncol. 27:2217–2224. 2009. View Article : Google Scholar : PubMed/NCBI

32 

Carus A, Ladekarl M, Hager H, Pilegaard H, Nielsen PS and Donskov F: Tumor-associated neutrophils and macrophages in non-small cell lung cancer: No immediate impact on patient outcome. Lung Cancer. 81:130–137. 2013. View Article : Google Scholar : PubMed/NCBI

33 

Lopez-Pastorini A, Riedel R, Koryllos A, Beckers F, Ludwig C and Stoelben E: The impact of preoperative elevated serum C-reactive protein on postoperative morbidity and mortality after anatomic resection of lung cancer. Lung Cancer. 109:68–73. 2017. View Article : Google Scholar : PubMed/NCBI

34 

Leuzzi G, Galeone C, Gisabella M, Duranti L, Taverna F, Suatoni P, Morelli D and Pastorino U: Baseline C-reactive protein level predicts survival of early-stage lung cancer: Evidence from a systematic review and meta-analysis. Tumori. 102:441–449. 2016. View Article : Google Scholar : PubMed/NCBI

35 

Kameda K, Eguchi T, Lu S, Qu Y, Tan KS, Kadota K, Adusumilli PS and Travis WD: Implications of the eighth edition of the TNM proposal: Invasive versus total tumor size for the T descriptor in pathologic stage I–IIA lung adenocarcinoma. J Thorac Oncol. 13:1919–1929. 2018. View Article : Google Scholar : PubMed/NCBI

36 

Ohtaki Y, Ishii G, Nagai K, Ashimine S, Kuwata T, Hishida T, Nishimura M, Yoshida J, Takeyoshi I and Ochiai A: Stromal macrophage expressing CD204 is associated with tumor aggressiveness in lung adenocarcinoma. J Thorac Oncol. 5:1507–1515. 2010. View Article : Google Scholar : PubMed/NCBI

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December-2019
Volume 18 Issue 6

Print ISSN: 1792-0981
Online ISSN:1792-1015

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APA
Sumitomo, R., Hirai, T., Fujita, M., Murakami, H., Otake, Y., & Huang, C. (2019). M2 tumor‑associated macrophages promote tumor progression in non‑small‑cell lung cancer. Experimental and Therapeutic Medicine, 18, 4490-4498. https://doi.org/10.3892/etm.2019.8068
MLA
Sumitomo, R., Hirai, T., Fujita, M., Murakami, H., Otake, Y., Huang, C."M2 tumor‑associated macrophages promote tumor progression in non‑small‑cell lung cancer". Experimental and Therapeutic Medicine 18.6 (2019): 4490-4498.
Chicago
Sumitomo, R., Hirai, T., Fujita, M., Murakami, H., Otake, Y., Huang, C."M2 tumor‑associated macrophages promote tumor progression in non‑small‑cell lung cancer". Experimental and Therapeutic Medicine 18, no. 6 (2019): 4490-4498. https://doi.org/10.3892/etm.2019.8068