Characterization of predictive markers and target genes of ProLindac, a novel DACH-platinum compound, compared to oxaliplatin and cisplatin in human cancer cell lines
Authors: Maria Serova, Aida Ghoul, Ivan Bieche, Michel Vidaud, Esteban Cvitkovic, David Nowotnik, Maurizio D'Incalci, Massimo Broggini, Eugenio Erba, Sandrine Faivre, Eric Raymond
Journal: Cancer Research (2008)

3348    Background:  Platinum-based chemotherapeutic agents (cisplatin and oxaliplatin) exert their activity primarily by binding to cellular DNA, leading to apoptosis. Diaminocyclohexane platinums (DACH), of which oxaliplatin is the only one available, exert different effects from cisplatin and carboplatin on expression of DNA-repair- and cell cycle-related genes. ProLindac, a novel DACH-platinum (Pt) complex, linked to a hydrophilic copolymer that acts as a macromolecular carrier, is currently in Phase I/II single-agent development. Our study aimed to determine the molecular mechanisms of ProLindac action, and predictive factors of sensitivity and related target genes in cancer cell lines, compared to oxaliplatin and cisplatin.   Methods : Antiproliferative effects of ProLindac, oxaliplatin and cisplatin were evaluated in human colon (HT29, HCT116, HCT116-Δp53, HCT116-CH3), lung (HOP62) and ovarian (IGROV1) cancer cell lines, by MTT assay. Cell cycle changes and apoptosis induction were evaluated by FACS analysis. Expression of 11 genes was determined using q-RT-PCR.   Results : ProLindac displayed cytotoxic effects against human cancer cell lines (IC 50  values: 0.3-2.2 µM), HT29 being the most sensitive. At equimolar concentrations, ProLindac and oxaliplatin displayed similar spectra of activity, different from that of cisplatin. Exposure to ProLindac led to accumulation of cells in the G2/M phase of the cell cycle, and to apoptosis induction. In HCT116 (p53 + , MMR - ) cells, these effects were associated with >5-fold increase of p21 expression and ~10-fold decrease of Ki67 and NEK2 mRNA levels. Experiments with HCT116-derived cell lines stably carrying additional chromosome 3 or deprived p53 (HCT116-CH3 and HCT116-Δp53, respectively) demonstrated that the effects of ProLindac on gene expression are p53-dependent without participation of mismatch repair (MMR) genes. Oxaliplatin (but not cisplatin) displayed similar effects on gene expression. ProLindac, oxaliplatin and cisplatin cytotoxicity experiments showed no significant impact of p53 and MMR in ProLindac and oxaliplatin response, whilst cisplatin was less active in HCT116-CH3 and HCT116-Δp53 than in parental HCT116 cells. To determine the predictive factors of sensitivity to ProLindac we studied the basal level of expression of several DNA-repair, cell cycle and metabolism-related genes in a panel of cancer cell lines. Low expression of MLH1, MDR1 and GSTP1 genes correlates with ProLindac sensitivity.   Conclusions:  ProLindac displayed a cytotoxic profile similar to that of oxaliplatin in most human cancer cell lines. Some proteins implicated in DNA-repair and metabolism may be important factors of ProLindac cytotoxicity; cellular effects of ProLindac and oxaliplatin were associated with changes of expression of several cell cycle-related genes.