Establishment of Adaptive Drug-resistant Colorectal Cancer Cell Model

Abstract

Colorectal cancer (CRC) ranks among the most prevalent cancers and contributes significantly to cancer-related fatalities. Chemoresistance in CRC poses a considerable therapeutic challenge, underscoring the need to comprehend the underlying mechanisms for the development of alternative strategies to overcome this resistance. Utilizing isogenic cell lines with acquired drug resistance is one of the prominent experiment approaches for studying chemoresistance, enabling the exploration of adaptive cellular responses to chemotherapeutic agents that confer resistance in cancers. However, establishing such cell models is challenging, and there are limited readily available protocols for scientists as references. This paper aims to elucidate the methodology for establishing a laboratory isogenic adaptive chemoresistant cell model, focusing on a cisplatin-resistant CRC cell model. From a panel of three human CRC cell lines, HCT116 was selected as the parent cell line due to its high cisplatin sensitivity. HCT116 cells were subjected to pulsed or continuous cisplatin treatments that resulted in successful selection of seventeen HCT116 sublines that exhibited varying degrees of cisplatin resistance. Only one HCT116 subline with transient acquired cisplatin resistance was established using pulsed exposure method while the method involved continuous cisplatin treatment has successfully established two resistant lines HCT116/I24781 and HCT116/I248 demonstrate 24.5-fold and 19.2-fold resistance respectively. These resistant cells showed significantly reduced growth rate with slight change in cell morphology and relatively stable resistance that remained unaffected for 8 continuous passages in cisplatin-free environment and 2 cryopreservation cycles. Together, these results suggest that continuous exposure with stepwise dose increase of drug is promising for establishing adaptive drug-resistant cell lines with significant drug resistance.