Multidrug resistance (MDR) is an important obstacle that limits the efficacy of chemotherapy in many types of cancer. In this study, 14 novel asymmetrical DHPs possessing pyridyl alkyl carboxylate substitutions at C3 and alkyl carboxylate groups at C5 in addition to a nitroimidazole or nitrophenyl moiety at C4 position were synthesized. Calcium channel blocking (CCB) activity was measured in guinea pig ileal longitudinal smooth muscle. Cytotoxicity was tested on 4 human cancer cell lines, while MDR reversal capacity was examined on P-glycoprotein overexpressing doxorubicin resistant MES-SA-DX5 and compared with non-resistant MES-SA cells. Compounds showed different CCB (IC50: 29.3 nM-4.75 μM) and cytotoxic activities (IC50: 6.4 to more than 100 μM). Several compounds having nitrophenyl moiety at C4, could significantly reverse resistance to doxorubicin at 0.5 and 1 μM. The most active ones were 7e and 7g containing ethyl carboxylate and isopropyl carboxylate at C5, respectively. CCB activity, which is considered an undesirable effect for these agents, of 7e and 7g were 33 and 20 times lower than nifedipine, respectively. In conclusion, the newly synthesized asymmetrical DHP compounds showed promising MDR reversal and antitumoral activities with low CCB effects and could be of therapeutic value in drug resistant cancer.

Abstract. MicroRNA (miR), as non-coding small RNA, are key regulators of cancer-related biological cell processes and contribute to tumor growth through regulation of groups of pro-and anti-apoptotic genes. The present study aimed to investigate the effects of miR-29a on the expression of genes involved in apoptosis, including p21, B-cell lymphoma 2 (BCL-2), p53 and survivin. The MCF-7 breast cancer cell line was transfected with anti-miR-29a and treated with Taxol in subdivided treatment groups including: Scramble; anti-miR-29a; anti-miR-29a + Taxol; Taxol; and control. Expression levels of p21, BCL-2, p53 and survivin were evaluated using reverse transcription-quantitative polymerase chain reaction. miR-29a knockdown resulted in p21 and p53 upregulation and a decrease in survivin expression. These results indicated that miR-29a inhibition regulates apoptosis. The present data suggested that miR-29a inhibition may be a promising strategy for the induction of apoptosis of tumor cells.