Involvement of MKP-1 and Bcl-2 in acquired cisplatin resistance in ovarian cancer cells

Abstract

Although cisplatin is a very effective anticancer agent against several types of cancer including ovarian cancer, the mechanisms of acquired resistance are not fully understood. By chronically exposing cisplatin to ovarian cancer cell lines, we established two cisplatin-resistant cell lines OV433 and tOV112D. Our results indicate that the mechanisms underlying their cisplatin resistance are distinct. In OV433 cells, cisplatin resistance is associated with increased expression of mitogen-activated protein kinase (MAPK) phosphatase-1 (MKP-1). By knocking down MKP-1 expression by siRNA or inhibiting MKP-1 expression by its pharmacological inhibitor triptolide, cisplatin-resistant OV433 cells became cisplatin-sensitive and subsequently increased cisplatin-induced apoptosis. In tOV112D cells, on the other hand, acquired cisplatin resistance is associated with increased levels of Bcl-2 protein. By inhibiting the activity of Bcl-2 protein with its pharmacological inhibitor gossypol or knocking down Bcl-2 expression by siRNA, cisplatin-resistant tOV112D cells became cisplatin-sensitive and subsequently increased cisplatin-induced apoptosis. therefore, our data suggest that the mechanisms of acquired cisplatin resistance vary among ovarian cancer cells, which involve upregulation of molecules associated with the cell survival pathways.

MicroRNA-100 Resensitizes Resistant Chondrosarcoma Cells to Cisplatin through Direct Targeting of mTOR

“…It has been reported that altered expression and activation of genes involved in cell death pathways were involved in the cisplatin resistance (Galluzzi et al, 2012). A recent study showed the activity of BCL-2 which is an anti-apoptosis protein contributed to the cisplatin resistance in chondrosarcoma (Wang et al, 2009). Overexpression of BCL-2 rendered chondrosarcoma cells resistant to cisplatin treatments, while BCL-2 inhibition can reverse chemoresistance of chondrosarcoma in vitro.…”

Role of Autophagy in Cisplatin Resistance in Ovarian Cancer Cells

“…MTT Assays-MTT assays were performed as described previously (28). Briefly, cells were left untreated or pretreated with U0126 (10 M), SB203580 (10 M), SP600125 (10 M), or 3-MA (1 mM) for 30 min and then left untreated or treated with cisplatin.…”

“…Western Blot Analysis-Cell lysates were prepared as described previously (28), and protein concentration was determined using the Protein Assay Kit (Bio-Rad). Cell lysates were electrophoresed through denaturing polyacrylamide gels and transferred to a PVDF membrane (Millipore).…”

Post-translational regulation of mitogen-activated protein kinase phosphatase-2 (MKP-2) by ERK

“…Cell lysates were prepared as described previously. 31 Briefly, cells were washed twice in ice-cold PBS, and immediately lysed in lysis buffer. Protein concentrations were quantified by a Protein Assay Kit (Biorad), and total proteins (100 μg) were loaded on SDS-PAGE gels, transferred onto polyvinylidene difluoride membrane (Millipore).…”