Hsa_Circ_0007841 Enhances Multiple Myeloma Chemotherapy Resistance Through Upregulating ABCG2

The current researches have reported that circular RNA is an important regulatory factor in the progression of various human disease. However, the function and mechanism of most circular RNAs remain unknown in cancers including multiple myeloma. Our study has confirmed that hsa_circ_0007841 is up regulated in U266 doxorubicin resistant cells (U266R) and 8226 doxorubicin resistant cells (8226R) compared to U266 parent cells (U266P) and 8226 parent cells (8226P). Silence of hsa_circ_0007841 in U266R and 8226R could reduce the half-maximal inhibitory concentration which indicated reduction in chemoresistance. In doxorubicin resistant cells, the messenger RNA and protein level of ATP-binding cassette transporters G2 increased. Silence of hsa_circ_0007841 in drug resistant cells could decrease both the messenger RNA and protein levels of ATP-binding cassette transporters G2; reexpression of hsa_circ_0007841 could block the reduction. However, overexpression of hsa_circ_0007841 could effectively upregulate the ATP-binding cassette transporters G2 messenger RNA and protein level. Inhibition of ATP-binding cassette transporters G2 could block hsa_circ_0007841 overexpression induced chemoresistance in U266P and 8226P cells. What's more, inhibition of ATP-binding cassette transporters G2 could reduce differences of half-maximal inhibitory concentration between parent cell lines and drug-resistant cell lines. Our data collectively suggest a new model in which hsa_circ_0007841 promotes acquired chemotherapy resistance by upregulating ATP-binding cassette transporters G2 providing a novel molecular basis of chemotherapy in multiple myeloma cancer.