PEG-liposomal oxaliplatin potentialization of antitumor efficiency in a nude mouse tumor-xenograft model of colorectal carcinoma

The non-selectivity of chemotherapeutics between normal tissue and pathological sites poses a challenge for the treatment strategy for advanced colorectal carcinoma. To obtain sufficient antitumor activity, optimization of the therapeutic regimen is of great importance. We investigated PEG-liposomal oxaliplatin potentialization of antitumor efficiency in a nude mouse tumor-xenograft model of colorectal carcinoma. A tumor-bearing nude mouse model, intravenous injections of (Dio)-labeled PEG-liposomes via tail vein and fluorescence imaging with in vivo imaging system were employed. Mice were treated with free L-oHP, PEG-liposomal L-oHP via the tail vein, followed by analysis of the accumulation of L-oHP in tumor tissues by high-performance liquid chromatography (HPLC), observation of the tumor volume and the survival rate. Apoptosis and proliferation of tumors were detected by TUNEL assay and immunohistochemistry. The mRNA and protein levels of Bcl-2, Bax, caspase-3 (P17) and Ki-67 were determined by RT-PCR and Western blotting. Fluorescence imaging with in vivo imaging showed PEG-liposome targeting in tumor tissues. After intravenous injections of PEG-liposomal oxaliplatin, tumor tissue maximum accumulation of L-oHP was 9.37±0.79 µg/g at 24 h; The tumor volume was significantly suppressed, and mice showed longer survival, compared with the free oxaliplatin group. Apoptosis increased, but proliferation decreased in tumor tissues. The mRNA expression of Bcl-2 and Ki-67 was down-regulated, while Bax and caspase-3 expression was up-regulated. Protein expression of Bcl-2 was down-regulated, while Bax and P17 expression was up-regulated. The results indicate that PEG-liposomal oxaliplatin can improve antitumor efficiency in a nude mouse tumor-xenograft model of colorectal carcinoma.