Abstract: Multidrug resistance(MDR) is one of the main factors in the failure of chemotherapy against tumors, and multidrug resistance-associated protein 1(MRP1) is closely related to the generation of MDR. In this work, the interaction force between MRP1 and anti-MRP1 was measured via single-molecule force microscopy(SMFM), and the expression differences of MRP1 on human tongue cancer cells before and after treatment with high-dose bleomycin(BLM) were investigated. The results show that the interaction force between MRP1 and anti-MRP1 is about (182±35) pN as the loading rate is 2.5 μm/s. The expression of MRP1 on human tongue cancer cell membrane increased obviously after treatment with high-dose BLM. This work may provide a new method for studying the expression of MRP1 at the living cell level and can be helpful for the study of MDR.

Key words: Atomic force microcopy, Single molecule force spectroscopy, Multidrug resistance(MDR), Expression of MRP1