The checkpoint 1 kinase inhibitor LY2603618 induces cell cycle arrest, DNA damage response and autophagy in cancer cells

In this study, we investigated the molecular mechanisms underlying the antitumor activity of LY2603618, a potent and selective small molecule inhibitor of Chk1 protein kinase, in human lung cancer cells. Treatment of cancer cells with LY2603618 caused cell cycle arrest in the G2/M phase. A marked induction of DDR, including the phosphorylation of ATM, Chk2, p53 and histone H2AX, was observed after LY2603618 treatment. LY2603618 inhibited Chk1 autophosphorylation (S296 Chk1) and increased DNA damage-mediated Chk1 phosphorylation (S345 Chk1). In addition, LY2603618-treated lung cancer cells transitioned from LC3-I to LC3-II, a hallmark of autophagy. Blocking autophagy with chloroquine (CQ) further enhanced LY2603618′s inhibitory effect on cell viability/proliferation. LY2603618 also significantly increased p38 and c-Jun N-terminal kinase (JNK) phosphorylation. Pretreatment with the JNK inhibitor reduced cleavage of caspase-3 and PARP levels in LY2603618-treated cells. These results suggest the following: (i) the biological consequences of LY2603618 in lung cancer cells is associated with both inhibition of Chk1 phosphorylation on S296 and activation of the DNA damage response network; and (ii) the anticancer property of LY2603618 might be increased by inhibiting autophagy.
Source: Apoptosis - Category: Molecular Biology Source Type: research