5-FU resistant colorectal cancer cells possess improved invasiveness and βIII-tubulin expression

Abstract

Purpose: Elevated b III -tubulin levels are associated with resistance to a broad spectrum of drugs in different carcinomas and are associated with poor prognosis of different epithelial cancers. 5-Fluorouracil (5-FU) is a widely used standard drug in chemotherapeutic regimens for colorectal cancer treatment, although the resistance to 5-FU is a major obstacle to successful therapy. The aim of the study was to compare the invasive and adhesion properties and the expression levels of b III -tubulin in a 5-Fluorouracil (5-FU)-resistant colorectal cancer (CRC) cell line HCT116 and parental cells. Methods: The 5-FU-resistant cell line was established by continuous stepwise selection with increasing concentrations of 5-FU. Cell viability and properties were evaluated using MTT, adhesion and transwell invasion assays respectively. The expression of b III -tubulin was revealed by immunoblot and immunofluorescence. Results: The derivative line is 25-fold resistant to 5-FU and characterized by altered cell morphology, twice as many cells of the 5-FU-resistant line fail to adhere than is the case for the parental cell line and were characterized by enhanced invasiveness, accompanied by increased b III -tubulin expression. In addition, we found that loss of b III -tubulin expression was correlated with loss of 5-FU resistance. Conclusion: Our results indicate that even though 5-FU does not target microtubules, there appears to be a correlation between b III -tubulin expression and resistance to 5-FU and that this is particularly important with regard to invasiveness. These findings indicate a possible contribution of b III -tubulin to 5-FU resistance in vivo.