To establish L-OHP resistant human colorectal cancer cell line(HT-29/L-OHP), and detect the expression of related drug resistant gene LAPTM4β, and probe its role in the mechanism of L-OHP resistant.

Drug concentration gradient increasing intermittent induction method was used to establish L-OHP resistant human colorectal cancer cell line(HT-29/L-OHP); LAPTM4β-35 protein inhibitor was used in HT-29/L-OHP cell line, flow cytometry was adopted to detect cell apoptosis, and to compare L-OHP resistant of it with other HT-29/L-OHP cell line; RT-PCR was adopted to detect the expression of LAPTM4βmRNA; Western blot was used to detect the expression of LAPTM4β-35 protein.

L-OHP resistant human colorectal cancer cell line(HT-29/L-OHP)was established successfully.The flow cytometry result showed that LAPTM4β-35 protein inhibitor use in HT-29/L-OHP cell line lead to significantly lower L-OHP resistance than that of HT-29/L-OHP cell line.The expression of LAPTM4βmRNA of HT-29/L-OHP was significantly higher than parental cell plant HT-29, 5.613+ 0.139 and 1.105+ 0.187, respectively(P<0.05). The relative expression level of LAPTM4-35 in HT-29/L-OHP cell line and HT-29 cell line was 2.203+ 0.080 and 1.033+ 0.070, (P<0.05).

LAPTM4β is overexpressed in HT-29/L-OHP cell line, and it is closely related with L-OHP resistant of colorectal cancer, it could be used as a sensitive biomarker for drug resistance of colorectal cancer.