Shogaols at proapoptotic concentrations induce G2/M arrest and aberrant mitotic cell death associated with tubulin aggregation

Abstract

Shogaols have been previously reported to induce cancer cell death via multiple mechanisms, among which one analog 6-shogaol has been reported to cause microtubule damage through specific reaction with sulfhydryl groups in tubulin. In this study, a series of shogaols with different side chain lengths (4-, 6-, 8- and 10-shogaol) was synthesized and evaluated for antiproliferative activity in HCT 116 colon carcinoma and SH-SY5Y neuroblastoma cells. 4- and 6-shogaol were identified as lead compounds possessing the strongest antiproliferative activity. In the soft agar assay, the lead shogaols displayed dose-dependent inhibition on cancer cell colony formation under anchorage-independent conditions. Using HCT 116 as the selected cancer cell line, the molecular events linking shogaols-induced G(2)/M cell cycle arrest to apoptosis characterized by caspase 3 and PARP cleavage were investigated. At sublethal concentrations, the halt at G(2)/M phase was alleviated along time and cells survived. Conversely, proapoptotic concentrations of 4- and 6-shogaol induced irreversible G(2)/M arrest that was at least in part associated with down-regulation of cell cycle checkpoint proteins cdk1, cyclin B and cdc25C, as well as spindle assembly checkpoint proteins mad2, cdc20 and survivin. A dose- and time-dependent accumulation of insoluble tubulin in the insoluble fractions of cell lysates provided evidence that G(2) checkpoint failure led to disruption of microtubule turnover. In summary, our results conclude that shogaols cause apoptosis by inducing aberrant mitosis at least through the attenuation of cell cycle and spindle assembly checkpoint proteins.

Wogonoside induces cell cycle arrest and differentiation by affecting expression and subcellular localization of PLSCR1 in AML cells

“…Soft agar colony-formation assays were carried out after treatment with wogonoside for 4 days. 19 The colonies were viewed at 340 magnification to detect colony size and colony numbers, using an inverted microscope equipped with a color camera (Nikon Instruments Inc, Lewisville, TX). In vivo investigations were performed in BALB/c nude mice injected with U937 cells 20 and in nonobese diabetic/severe combined immunodeficiency (NOD/SCID) immunodeficient mice engrafted with primary human AML cells.…”

6-Shogaol induces apoptosis in human leukemia cells through a process involving caspase-mediated cleavage of eIF2α

“…The compound was also reported to inhibit breast cancer cell invasion by reducing MMP-9 expression via targeting the NF- k B activation cascade [9] or by inhibiting invade podium formation [12]. Our group and Gan et al have found that 6-shogaol induced G2/M cell cycle arrest and apoptosis characterized by caspase 3 and PARP cleavage in HeLa and HCT116 cells [3,13]. Despite enormous efforts performed to investigate the anticancer activities of 6-shogaol, to date, the study on induction of apoptosis induced by 6-shogaol in human leukemia cells has not yet been explored, nor have the relationships between 6-shogaol-mediated anti-leukemic activity and cell signaling cascades been examined in depth.…”

10-Shogaol, an Antioxidant from Zingiber officinale for Skin Cell Proliferation and Migration Enhancer

“…6-Shogaol was described to not only have anti-cancer and anti-inflammatory capabilities, but also had the potential to be used as an anti-metastatic treatment [18]. At pro-apoptotic concentrations, 10-shogaol, an extract from ginger, was able to induce G(2)/M arrest and abnormal mitotic cell death that is associated with tubulin aggregation [19]. 10-Shogaol, the only non-pungent compound among the gingerols and shogaols, has the ability to stimulate the increase of adrenaline secretion [20].…”