Abstract: Objective: To investigate the effect of parthenolide (PTL) and PKC inhibitor on human gastrointestinal stromal tumor (GIST) cell proliferation and apoptosis and the mechanism involved. Methods: Human GIST cell lines were cultured in vitro, and the cell proliferation rate of GIST, was determinate by MTT; flow cytometry was used to test the early apoptosis rate of GIST; Western blot assay was applied to detected the expression of endoplasmic reticulum stress-related proteins, GRP78 and GADD153. There are four groups: control group, PTL group, PKC inhibitor group, combine PTL and PKC inhibitor group.Results: PTL and PKC inhibitor combination therapy for GIST was significantly more effective than a single-drug therapy (P <0.05); to early apoptosis rate, the combination therapy for GIST cells was significantly higher than that medication alone group (P <0.05). the expression of endoplasmic reticulum stress-associated protein GRP78 and GADD153 is obviously higher in PTL and PKC inhibitor combination group than that in medication alone group (P <0.05). Conclusions: PTL and PKC inhibitor combination therapy for GIST cells induce apoptosis, which was possible mediated via endoplasmic reticulum stress pathway.

Key words: GIST cells, PKC inhibitor, PTL, Apoptosis