Mechanism of cross-resistance and collateral sensitivity of cisplatin-resistant cancer

Abstract

위암세포에서 cisplatin 농도에 따라 출현하는 내성기전을 규명하고자 cisplatin 내성 위암세포주인 SNU-601/Cis2세포와 SNU-601/Cis10세포는 약물감수성세포인 SNU-601/WT세포에 각각 2 ㎍/ml와 10 ㎍/ml cisplatin을 계속해서 처치하여 선별되었다. MTT assay결과 SNU-601/Cis2세포와 SNU-601/Cis10세포는 SNU-601/WT세포와 비교시 각각 49 배와 530배 이상의 내성을 보였다. 뿐만 아니라 SNU-601/Cis2세포는 carboplatin (10.6배), heptaplatin (18.5배), doxorubicin (44.9배), mitomycin C (56.8배) 및 5-fluorouracil (64.4배)에 교차내성을 보였으나, SNU-601/Cis10세포는 SNU-601/Cis2세포와 비교시 cisplatin을 제외하고 이들 약물에 측부 감수성을 보였다. RT-PCR 방법으로 유전자 발현을 측정한 결과 cisplatin 내성 위암 세포주에서 metallothionein, catalase, copper/zinc 및 manganese superoxide dismutases, P-glycoprotein 및 breast cancer resistance protein는 증가되어 있으나 lung resistance protein, multidrug resistance-associated protein, 및 ATP7B는 관여되지 않아다. SNU-601/Cis2 세포에서 과산화수소와 형광탐식자를 이용하여 반응성산소종을 측정한 결과 SNU-601/WT세포와 SNU-601/Cis10 세포와 비교시 현저히 감소되어 있었다. 이상의 결과로 부터 SNU-601/Cis2와 SNU-601/Cis10세포는 다약물내성 표현형을 보였으며, 농도에 따른 교차내성과 측부 감수성 기전으로 배출펌프나 항산화 유전자발현의 변화가 일부 관여하는 것으로 생각된다.|The cisplatin-resistant gastric cancer sublines,SNU-601/Cis2 and SNU-601/Cis10, werederived from ahuman gastric cancer cell line, SNU-601/WT, by the continuous exposure to 2 and 10 ㎍/ml cisplatin, respectively. The possible mechanisms of cross resistance and the collateral sensitivity of both resistant cells to various anticancerdrugs were examined.The MTT assay showed that the SNU-601/Cis2 and SNU-601/Cis10 cells were 49- to and over 530-fold more resistant to cisplatin,respectively compared with the SNU-601/WT cells. In addition, the SNU-601/Cis2 cells showed cross-resistance to carboplatin (10.62-fold),heptaplatin (18.53 -fold), doxorubicin (44.93-fold), mitomycin C (56.76-fold)and 5-fluorouracil (64.36-fold)as compared to with the SNU-601/WT cells where as the SNU-601/Cis10 cells displayed collateralsensitivity to these drugs with the exception of cisplatin as compared to with the SNU-601/Cis2 cells. The RT-PCR assay indicates that metallothionein, catalase, copper/zinc and manganese containing superoxide dismutases, P-glycoprotein and the breast cancer resistance protein but not the lung resistance protein, multidrug resistance-associated protein,andATP7B could might be involved in cisplatin resistance in the SNU-601/Cis2 cells. The involvementof antioxidants in SNU-601/Cis2cellswassupportedby itssignificantly enhanced reactive oxygen species-scavenging activity as compared with that of the SNU-601/WT or SNU-601/Cis10 cells when determined using a hydrogen peroxide and a fluorescent probe, dichlorofluorescin diacetate. These results suggest that these cisplatin-resistant gastric cancer sublines display the multidrug resistance phenotype in a concentration-independent manner. In addition, altered expression ofthe antioxidantand transporter genes might be involved in the cross-resistanceand collateral sensitivity of thecisplatin-resistant gastric cancer cell lines to anticancer drugs.