Assessment of cytotoxicity, apoptosis and DNA damages in Colo320 colorectal cancer cells selected for oxaliplatin resistance

Abstract

Despite the notable efficacy of oxaliplatin in the treatment of colorectal cancers, the metastatic tumours ultimately become resistant to the drug. This study investigated whether the oxaliplatin-resistant cells display different behaviour to this drug versus the sensitive cells and if this difference may be further exploited into the clinical treatments improvement. In order to establish a stable cell line resistant to oxaliplatin, a human colorectal cancer cell line (Colo320) was exposed to increasing doses of the drug up to the clinically relevant plasma concentration. Four cell groups with different levels of chemoresistance were subjected to additional doses of oxaliplatin, and their cytotoxicity, apoptosis and DNA damage production were assessed. Cells selected for resistance to oxaliplatin reacted differently to the application of additional doses of the drug, displaying lower toxicity and cellular death and fewer DNA cross-links formation, in accordance with the extent of the oxaliplatin pretreatments. As the cross-links formation by oxaliplatin being the main cause for cytotoxicity of this drug and a correlation between cytotoxicity and clinical outcome being shown repeatedly, we consider that the evaluation of oxaliplatin-induced cytotoxicity, apoptosis and DNA damage could be a valuable tool to assess the tumour cells sensitivity and thus to predict the response to chemotherapy.

Oxaliplatin induces different cellular and molecular chemoresistance patterns in colorectal cancer cell lines of identical origins

“…Our results are comparable to other previous findings on parental and resistant Colo320 cells [11] and on sensitive Colo320 and HT-29 cells [7,17]. …”

“…In an earlier study, aiming to evaluate the differences in the behavior of the cells selected for L-OHP resistance compared to the sensitive ones, we assessed the cytotoxicity, apoptosis and induction of DNA damages by L-OHP in Colo320 CC cell line. We found lower toxicity, cellular death and fewer DNA damages, in the cells treated previously with L-OHP as compared to the parental ones [11]. In the present study we performed a comparative study on two CC cell lines (Colo320 and HT-29) with identical origins (adenocarcinomas) and their L-OHP resistant counterparts (Colo320R and HT-29R) obtained by prolonged exposure to L-OHP.…”

“…The fact that in Colo320R cell line we still could detect cross-links confirms once more the higher sensitivity of this cell line to L-OHP as compared to HT-29. In a previous study we observed changes in the comet tails length according to the degree of the treatment with L-OHP, indicating the presence or absence of the DNA cross-links induced by L-OHP on the tested cell lines [11]. In another study we induced standardized DNA strand breaks via ionizing irradiation and compared the cross-links formation capacity of L-OHP vs CDDP in 3 CC cell lines (Colo320, Caco-2 and HT-29) [17].…”

“…The initial dose was 0.01 μg/ml and the final concentration (0.87 μg/ml) corresponded to the clinically relevant plasma concentration of L-OHP (2 μmol/l) [14]. The resistant variant of Colo320 (Colo320R) was obtained and described previously [11]. For the HT-29 cell line we used the same procedure, sequentially increasing concentrations of the drug (with 0.05 μg/ml) being added to the cell culture at every second passage.…”

Oct-4 is required for an antiapoptotic behavior of chemoresistant colorectal cancer cells enriched for cancer stem cells: Effects associated with STAT3/Survivin

“…However, approximately 40% of CRCs remain refractory to FOLFOX. Mechanisms of resistance to platinum agents such as oxaliplatin include enhanced DNA damage repair, decreased drug accumulation, detoxification and inactivation of platinum compounds [11,12]. Over the last few years there has been an increase in studies examining drug resistance mechanisms in malignant tumors through the establishment of drug resistant cell lines [13][14][15][16].…”