Tumor-suppressive microRNA-let-7a inhibits cell proliferation via targeting of E2F2 in osteosarcoma cells

Iwasaki,Tatsuya; Tanaka,Kazuhiro; Kawano,Masanori; Itonaga,Ichiro; Tsumura,Hiroshi

doi:10.3892/ijo.2015.2867

Tumor-suppressive microRNA-let-7a inhibits cell proliferation via targeting of E2F2 in osteosarcoma cells

Authors:
- Tatsuya Iwasaki
- Kazuhiro Tanaka
- Masanori Kawano
- Ichiro Itonaga
- Hiroshi Tsumura
View Affiliations

Affiliations: Department of Orthopaedic Surgery, Faculty of Medicine, Oita University, Oita 879-5593, Japan
Published online on: February 3, 2015 https://doi.org/10.3892/ijo.2015.2867
Pages: 1543-1550

Metrics: Total Views: 0 (Spandidos Publications: | PMC Statistics: )

Metrics: Total PDF Downloads: 0 (Spandidos Publications: | PMC Statistics: )

Cited By (CrossRef): 0 citations Loading Articles...

Abstract

MicroRNAs (miRNAs) regulate cell proliferation and differentiation by silencing gene expression at the post-transcriptional level; moreover, by binding to the complementary sequences within mRNAs in cancer cells, these small non-coding RNA molecules can function as tumor suppressors or oncogenes. Recently, the dysregulation of miRNA expression has been found to be associated with increased tumorigenicity and poor prognosis in several cancer types, including osteosarcoma (OS). To identify potential oncogenic factors in OS, we analyzed changes in the expression profile of miRNAs and its downstream mRNAs in five OS cell lines and human mesenchymal stem cells (hMSCs) by a microarray-based approach. The expression of an miRNA-let‑7a was significantly downregulated and E2F2 was significantly upregulated in all tested OS cells compared with hMSCs. When let-7a was transfected into OS cell lines, the expression of E2F2 in the cells was greatly suppressed, suggesting that E2F2 is a target of miRNA-let-7a in OS cells. The transfection of let-7a further inhibited cell cycle progression and proliferation of OS cells. In addition, let-7a overexpression in OS cells significantly suppressed the tumor growth in vivo. The present study demonstrates the novel mechanism that regulates E2F2 expression via miRNA-let-7a in OS cells. Because E2F2 is pivotal in promoting cell growth through the regulation of several genes, our results might facilitate the development of new therapeutic targets for the treatment of OS.

View Figures

View References

1	Ottaviani G and Jaffe N: The epidemiology of osteosarcoma. Cancer Treat Res. 152:3–13. 2009. View Article : Google Scholar
2	Bielack SS, Kempf-Bielack B, Delling G, Exner GU, et al: Prognostic factors in high-grade osteosarcoma of the extremities or trunk: an analysis of 1,702 patients treated on neoadjuvant cooperative osteosarcoma study group protocols. J Clin Oncol. 20:776–790. 2002. View Article : Google Scholar : PubMed/NCBI
3	Kansara M and Thomas DM: Molecular pathogenesis of osteosarcoma. DNA Cell Biol. 26:1–18. 2007. View Article : Google Scholar : PubMed/NCBI
4	Marulanda GA, Henderson ER, Johnson DA, Letson GD and Cheong D: Orthopedic surgery options for the treatment of primary osteosarcoma. Cancer Control. 15:13–20. 2008.
5	Bartel DP: MicroRNAs: genomics, biogenesis, mechanism, and function. Cell. 116:281–297. 2004. View Article : Google Scholar : PubMed/NCBI
6	Calin GA, Dumitru CD, Shimizu M, et al: Frequent deletions and down-regulation of micro- RNA genes miR15 and miR16 at 13q14 in chronic lymphocytic leukemia. Proc Natl Acad Sci USA. 99:15524–15529. 2002. View Article : Google Scholar : PubMed/NCBI
7	Ruvkun G: Clarifications on miRNA and cancer. Science. 311:36–37. 2006. View Article : Google Scholar : PubMed/NCBI
8	Calin GA and Croce CM: MicroRNA signatures in human cancers. Nat Rev Cancer. 6:857–866. 2006. View Article : Google Scholar : PubMed/NCBI
9	Garofalo M, Di Leva G, Romano G, et al: miR-221&222 regulate TRAIL resistance and enhance tumorigenicity through PTEN and TIMP3 downregulation. Cancer Cell. 16:498–509. 2009. View Article : Google Scholar : PubMed/NCBI
10	Acunzo M, Visone R, Romano G, et al: miR-130a targets MET and induces TRAIL-sensitivity in NSCLC by downregulating miR-221 and 222. Oncogene. 31:634–642. 2012.
11	Garofalo M, Romano G, Di Leva G, et al: EGFR and MET receptor tyrosine kinase-altered microRNA expression induces tumorigenesis and gefitinib resistance in lung cancers. Nat Med. 18:74–82. 2011.PubMed/NCBI
12	Reinhart BJ, Slack FJ, Basson M, Pasquinelli AE, Bettinger JC, Rougvie AE, Horvitz HR and Ruvkun G: The 21-nucleotide let-7 RNA regulates developmental timing in Caenorhabditis elegans. Nature. 403:901–906. 2000. View Article : Google Scholar : PubMed/NCBI
13	Takamizawa J, Konishi H, Yanagisawa K, et al: Reduced expression of the let-7 microRNAs in human lung cancers in association with shortened postoperative survival. Cancer Res. 64:3753–3756. 2004. View Article : Google Scholar : PubMed/NCBI
14	Johnson SM, Grosshans H, Shingara J, et al: RAS is regulated by the let-7 microRNA family. Cell. 120:635–647. 2005. View Article : Google Scholar : PubMed/NCBI
15	Lee YS and Dutta A: The tumor suppressor microRNA let-7 represses the HMGA2 oncogene. Genes Dev. 21:1025–1030. 2007. View Article : Google Scholar : PubMed/NCBI
16	Akao Y, Nakagawa Y and Naoe T: let-7 microRNA functions as a potential growth suppressor in human colon cancer cells. Biol Pharm Bull. 29:903–906. 2006. View Article : Google Scholar : PubMed/NCBI
17	Attwooll C, Lazzerini Denchi E and Helin K: The E2F family: specific functions and overlapping interests. EMBO J. 23:4709–4716. 2004. View Article : Google Scholar : PubMed/NCBI
18	Trimarchi JM and Lees JA: Sibling rivalry in the E2F family. Nat Rev Mol Cell Biol. 3:11–20. 2002. View Article : Google Scholar : PubMed/NCBI
19	Dimova DK and Dyson NJ: The E2F transcriptional network: old acquaintances with new faces. Oncogene. 24:2810–2826. 2005. View Article : Google Scholar : PubMed/NCBI
20	Wong JV, Dong P, Nevins JR, Mathey-Prevot B and You L: Network calisthenics: control of E2F dynamics in cell cycle entry. Cell Cycle. 10:3086–3094. 2011. View Article : Google Scholar : PubMed/NCBI
21	Helin K: Regulation of cell proliferation by the E2F transcription factors. Curr Opin Genet Dev. 8:28–35. 1998. View Article : Google Scholar : PubMed/NCBI
22	Aguda BD, Kim Y, Piper-Hunter MG, Friedman A and Marsh CB: MicroRNA regulation of a cancer network: consequences of the feedback loops involving miR-17–92, E2F, and Myc. Proc Natl Acad Sci USA. 105:19678–19683. 2008. View Article : Google Scholar
23	Lal A, Navarro F, Maher CA, et al: miR-24 Inhibits cell proliferation by targeting E2F2, MYC, and other cell-cycle genes via binding to ‘seedless’ 3′UTR microRNA recognition elements. Mol Cell. 35:610–625. 2009. View Article : Google Scholar : PubMed/NCBI
24	Nelson KM and Weiss GJ: MicroRNAs and cancer: past, present, and potential future. Mol Cancer Ther. 7:3655–3660. 2008. View Article : Google Scholar : PubMed/NCBI
25	Hu X, Guo J, Zheng L, et al: The heterochronic microRNA let-7 inhibits cell motility by regulating the genes in the actin cytoskeleton pathway in breast cancer. Mol Cancer Res. 11:240–250. 2013. View Article : Google Scholar : PubMed/NCBI
26	Yang Q, Jie Z, Cao H, Greenlee AR, Yang C, Zou F and Jiang Y: Low-level expression of let-7a in gastric cancer and its involvement in tumorigenesis by targeting RAB40C. Carcinogenesis. 32:713–722. 2011. View Article : Google Scholar : PubMed/NCBI
27	Chen C and Wells AD: Comparative analysis of E2F family member oncogenic activity. PLoS One. 2:e9122007. View Article : Google Scholar : PubMed/NCBI
28	Lin PC, Chiu YL, Banerjee S, et al: Epigenetic repression of miR-31 disrupts androgen receptor homeostasis and contributes to prostate cancer progression. Cancer Res. 73:1232–1244. 2013. View Article : Google Scholar :
29	Fujiwara K, Yuwanita I, Hollern DP and Andrechek ER: Prediction and genetic demonstration of a role for activator E2Fs in Myc-induced tumors. Cancer Res. 71:1924–1932. 2011. View Article : Google Scholar : PubMed/NCBI
30	Okamoto OK, Oba-Shinjo SM, Lopes L and Nagahashi Marie SK: Expression of HOXC9 and E2F2 are up-regulated in CD133⁺ cells isolated from human astrocytomas and associate with transformation of human astrocytes. Biochim Biophys Acta. 1769:437–442. 2007. View Article : Google Scholar : PubMed/NCBI
31	Dong Q, Meng P, Wang T, et al: MicroRNA let-7a inhibits proliferation of human prostate cancer cells in vitro and in vivo by targeting E2F2 and CCND2. PLoS One. 5:e101472010. View Article : Google Scholar : PubMed/NCBI
32	Sharma N, Timmers C, Trikha P, Saavedra HI, Obery A and Leone G: Control of the p53-p21CIP1 Axis by E2f1, E2f2, and E2f3 is essential for G1/S progression and cellular transformation. J Biol Chem. 281:36124–36131. 2006. View Article : Google Scholar : PubMed/NCBI
33	Nguyen-Vu T, Vedin LL, Liu K, et al: Liver x receptor ligands disrupt breast cancer cell proliferation through an E2F-mediated mechanism. Breast Cancer Res. 15:R512013. View Article : Google Scholar