Abstract 306: Antitumor effect of Wee1 inhibitor in gastric cancer cells

Abstract

Abstract Background: A cell cycle checkpoint is a key step to watch any damages and, it is needed to maintain genomic stability. Thus, to jeopardize cell cycle checkpoint is an attractive strategy for cancer treatment. Wee1 is a G2 cell cycle regulator that phosphorylate cdc2 on tyrosine 15 for inhibiting its activity. The activation of Wee1 can delay G2 phase progression and cells can have a chance to repair DNA damages. Therefore, to inhibit wee1 can accelerate DNA damage accumulation in the cell. AZD1775 is a first-in-class wee1 inhibitor. So far, previous studies showed the antitumor effect of AZD1775 as a mono-therapeutic agent or combination treatment with other chemo-agents. However, the activity of wee1 in gastric cancer (GC) cells is not yet fully understood. Thus, we would like to study whether AZD1775 has an antitumor effect against GC or not. Materials and methods: We determined the antitumor effects of AZD1775 on GC cells using a cytotoxicity assay, cell cycle analysis, immunofluorescence assay and western blotting by AZD1775 treatment. Results: AZD1775 effectively inhibit GC cell proliferation. The TP53 gene status or p-Wee1 expression levels were not associated with AZD1775 sensitivity. AZD1775 effectively down-regulated p-Wee1 and p-cdc2 expressions in SNU-601, a sensitive cell line. However, these effects were not significant in KATO-III cells, which is less sensitive to AZD1775. Cell cycle analysis revealed that the cells had different responses by AZD1775 treatment. SNU-601 cells were enriched in S phase when we decide cell cycle only by its DNA contents. However, KATO-III cells were arrested in G2/M phase. The sub-G1 population was dramatically increased only in SNU-601 cells. A population of BrdU-positive and p-HH3 positive cells was significantly increased in the SNU-601 cells which indicate that premature mitosis was increased. However, no differences were observed in KATO-III cells. Moreover, due to premature mitotic entry, multi-nucleated cells were observed only in SNU-601 cells. Conclusion: AZD1775 effectively inhibited the growth of GC cell lines. The inhibition of cdc2 by AZD1775 was observed only in a sensitive cell line. Moreover, early mitotic entry was induced by AZD1775, and it led the induction of mitotic catastrophe. This result indicates that AZD1775 have an antitumor effect on GC and the possibility of adoption to the clinical trial design. Citation Format: Seongyeong Kim, Ahrum Min, So Hyeon Kim, Dong Hyeon Ha, Hyemin Jang, Yu JIn Kim, Hee Jun Kim, Kyung-Hun Lee, Tae-Yong Kim, Do-Youn Oh, Yung-Jue Bang, Seock-Ah Im. Antitumor effect of Wee1 inhibitor in gastric cancer cells [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 306. doi:10.1158/1538-7445.AM2017-306