Cell Cycle Arrest and Cytochrome c-mediated Apoptotic Induction in A549 Human Lung Cancer Cells by MCS-C2, an Analog of Sangivamycin

Abstract

In the course of screening for novel modulators of cell cycle progression and apoptosis as anticancer drug candidates,we generated an analog of sangivamycin, MCS-C2, which was elucidated as 4-amino-6-bromo-7-cyclopentyl-7Hpyrrolo[2,3-d]pyrimidine-5-carboxamide. In the present study, we evaluated the molecular mechanisms of MCSC2-induced cell cycle arrest and apoptosis in A549 human lung cancer cells. To investigate the effects of MCS-C2 on cell cycle progression in A549 cells, we measured the DNA content of A549 cells treated with 5 μM MCS-C2 using flow cytometry. The analysis revealed an appreciable G2phase arrest in treated cells. This event was associated with significant upregulation of p53 and p21Cip1. In addition,the TUNEL assay was used to examine apoptotic induction in treated cells, and the effects of MCS-C2 on the expression of apoptosis-associated proteins were examined by Western blot. Apoptotic induction in MCS-C2-treated A549 cells was associated with cytochrome c release from mitochondria, which in turn resulted in the activation of caspase-9 and -3 and the cleavage of poly(ADP-ribose)polymerase (PARP). Based on these results, we conclude that MCS-C2 is a candidate therapeutic agent for the treatment of human lung cancer via upregulation and activation of p53.