Effect of pinostrobin from fingerroot boesenbergia pandurata on wee1 kinase activity in some cancer cell lines

Abstract

Fingerroot Boesenbergia pandurata or Krachai lueng (in Thai), is classified in Family Zingiberaceae. Previous study, pinostrobin a pure compound was isolated from B. pandurata and identified as an inhibitor of calcium signaling pathway in ZDS1 null mutant yeast Saccharomyces cerevisiae (Δzds1). Western blot analysis showed that, pinostrobin decreased the expression level and activity of Swe1 in the yeast calcium signaling pathway. SWE1 in S. cerevisiae is an ortholog gene of WEE1 in human. The aim of this research was to determine the anti-proliferative activity of pinostrobin on many human cancer cell lines and the effect of pinostrobin on level and activity of Wee1 kinase in Jurkat T-cell (Human acute T cell leukemia), BT474 (Human breast carcinoma cell line) and KATO III (Human stomach carcinoma cell line). The results revealed that pinostrobin showed chronic cytotoxicity effect against Jurkat T-cell, BT474 and KATO III as determined by MTT viability assay at IC50 values of 51.2 ± 1.61 µM, 61.9 ± 1.15 µM and 24.7 ± 4.5 µM, respectively. On the other hand, pinostrobin did not show cytotoxic effect to normal human red blood cells and white blood cells. Western blot analysis showed that pinostrobin could down regulate the level of Wee1 kinase as well as Wee1 kinase activity (P-Cdc2 level) in Jurkat T-cell, BT474 and KATO III. Consistent with down-regulation of Wee1 kinase activity, pinostrobin also down-regulated WEE1 expression as revealed by quantitative real-time PCR especially in Jurkat T-cells. The pinostrobin treatment affected the sensitive cancer cell lines differently. The treatment caused increase in sub G1 of Jurkat T-cell and BT474. However, the profile of cell cycle progression did not affect, while arrested KATO III in G2/M phase. In addition, pinostrobin induced apoptotic cell death by Annexin V staining in the pinostrobin sensitive cell lines. Interestingly, pinostrobin synergistically enhanced the antitumor efficacy of various DNA-damaging agents including gemcitabine and camptothecin on apoptotic cells death induction.