Abstract
Chemoresistance contributes to cancer relapse and increased mortality in a variety of cancer types, raising a pressing need to better understand the underlying mechanism. MUC1 is abnormally overexpressed in numerous carcinomas and associated with poor prognosis. However, the functional significance of MUC1 in chemoresistance has not been fully elucidated. Here, we showed that MUC1 expression was considerably induced in cells that had acquired chemoresistance at both transcriptional and post-translational levels. Using gain- and loss-of function approaches, we demonstrated a critical role of MUC1 in induction of drug resistance. Through stimulation of EGFR activation and nuclear translocation, MUC1 increased the expression of ATP-binding cassette transporter B1 (ABCB1). Remarkably, targeted suppression of EGFR or ABCB1 by both shRNAs and inhibitors effectively reversed chemoresistance. Moreover, co-administration of the inhibitors of MUC1–EGFR–ABCB1 with paclitaxel significantly blocked not only tumor growth but also relapse in xenograft mouse model. Our data collectively support a model in which MUC1 induces acquired chemotherapy resistance by upregulating ABCB1 in an EGFR-dependent manner, providing a novel molecular basis of using the EGFR inhibitor in MUC1-positive cancers to prevent chemotherapy resistance.
Highlights
Chemoresistance is one of the important mechanisms responsible for tumor recurrence and poor prognosis in a variety of cancer types.[1,2,3] Paclitaxel (PTX) is a tubulindisrupting drug in the management of a wide range of tumors.[4,5,6] studies have uncovered the mechanisms of PTX resistance in several malignancies, many critical issues remain, warranting further investigation
We found that PTX induced Mucin 1 (MUC1), which contributed to chemoresistance by upregulation of ABC transporter B1 (ABCB1) through cooperation with nuclear EGFR
Given the association of MUC1 with chemoresistance, we made an attempt to investigate a potential involvement of MUC1 in chemoresistance in cervical cancer and pulmonary mucoepidermoid lung carcinoma (PMC)
Summary
Chemoresistance is one of the important mechanisms responsible for tumor recurrence and poor prognosis in a variety of cancer types.[1,2,3] Paclitaxel (PTX) is a tubulindisrupting drug in the management of a wide range of tumors.[4,5,6] studies have uncovered the mechanisms of PTX resistance in several malignancies, many critical issues remain, warranting further investigation. Many chemotherapy drugs for cancer are substrates for ABCB1, including PTX, vincristine, doxorubicin and etoposide.[8,9]. Induced chemoresistance, several pharmacological inhibitors have been developed but with limited success in clinic because of toxicities, which is primarily attributed to the critical functions of ABC transporters in various normal tissues in the physiological clearance of catabolites and xenobiotics.[13,14]. Overexpression of MUC1 is found to induce transformation in cells and transgenic mouse models.[15,18]
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