Abstract
Chemotherapy has been widely used in treatment of cancer, both as systemic therapy and as part of local treatment. Unfortunately, many kinds of cancer are still refractory to chemotherapy. The anticancer drug resistance mechanisms have been extensively explored, yet have not been fully characterized. Recent works have underlined the involvement of noncoding RNAs in cancer development, with several studies regarding their possible involvement in the evolution of drug resistance. MicroRNAs (miRNAs) are endogenous small noncoding RNAs (20โ23 nucleotides) that negatively regulate the gene expressions at the postโtranscriptional level by base pairing to the 3โฒ untranslated region of target messenger RNAs. Evidence is emerging that particular microRNAs (miRNA) alterations are involved in the initiation and progression of human cancer. More recently, accumulating evidence is revealing an important role of miRNAs in anticancer drug resistance and miRNA expression profiling can be correlated with the development of anticancer drug resistance. The microโRNAโmediated form of drug resistance adds yet another mechanism of drug resistance. So, exploiting the emerging knowledge of miRNAs for the development of new human therapeutic applications for overcoming anticancer drug resistance will be important.