Overexpression of OATP1B3 confers apoptotic resistance in colon cancer.
Overexpression of OATP1B3 confers apoptotic resistance in colon cancer.
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DOI：
10.1158/0008-5472.can-08-1984
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发表时间：
2008-12-15
期刊：
影响因子：
11.2
通讯作者：
El-Rifai W
中科院分区：
文献类型：
--
作者：
Lee W;Belkhiri A;Lockhart AC;Merchant N;Glaeser H;Harris EI;Washington MK;Brunt EM;Zaika A;Kim RB;El-Rifai W
Organic anion transporting polypeptide 1B3 (OATP1B3, SLCO1B3) is normally expressed in hepatocytes. In this study, we demonstrated frequent overexpression of OATP1B3 in colorectal adenocarcinomas. Quantitative RT-PCR analysis of 17 colon tumors indicated tumoral overexpression of OATP1B3 by ~100 fold, compared to 20 normal colon samples (p<0.0001). Using immunohistochemistry on a tissue microarray containing 93 evaluable colon tumor specimens, we detected immunostaining of OATP1B3 in 75 colon adenocarcinomas (81%) and no immunostaining in normal samples. To determine the functional effects of OATP1B3 expression on drug-induced apoptosis, we used camptothecin and oxaliplatin on a panel of colorectal cancer cell lines stably overexpressing OATP1B3. The results indicated that OATP1B3 overexpression enhanced cell survival in RKO, HCT-8 and HCT116p53+/+ cells that harbor wildtype p53 but not in Caco-2 and HCT116p53-/- cells that lack p53, compared to the respective empty vector controls (p<0.01). The TUNEL assay confirmed that HCT116p53+/+ cells overexpressing OATP1B3 had significantly lower apoptotic levels compared to empty vector control (P<0.001). The overexpression of OATP1B3 reduced the transcriptional activity of p53, with subsequent reductions in transcript and protein levels of its downstream transcription targets (P21WAF1 and PUMA). Overexpression of a point mutation (G583E) variant of OATP1B3 lacking transport activity did not confer an antiapoptotic effect or affect p53 transcriptional activity, suggesting that the antiapoptotic effect of OATP1B3 may be associated with its transport activity. Taken together, our results suggest that OATP1B3 overexpression in colorectal cancer cells may provide a survival advantage by altering p53-dependent pathways.
