Susceptibility of Hep3B cells in different phases of cell cycle to tBid.
tBid is a pro-apoptotic molecule. Apoptosis inducers usually act in a cell cycle-specific fashion. The aim of this study was to elucidate whether effect of tBid on hepatocellular carcinoma (HCC) Hep3B cells was cell cycle phase specific. We synchronized Hep3B cells at G0/G1, S or G2/M phases by chemicals or flow sorting and tested the susceptibility of the cells to recombinant tBid. Cell viability was measured by MTT assay and apoptosis by TUNEL. The results revealed that tBid primarily targeted the cells at G0/G1 phase of cell cycle, and it also increased the cells at the G2/M phase. 5-Fluorouracil (5-FU), on the other hand, arrested Hep3B cells at the G0/G1 phase, but significantly reduced cells at G2/M phase. The levels of cell cycle-related proteins and caspases were altered in line with the change in the cell cycle. The combination of tBid with 5-FU caused more cells to be apoptotic than either agent alone. Therefore, the complementary effect of tBid and 5-FU on different phases of the cell cycle may explain their synergistric effect on Hep3B cells. The elucidation of the phase-specific effect of tBid points to a possible therapeutic option that combines different phase specific agents to overcome resistance of HCC.
Department of Surgery, The Chinese University of Hong Kong, Shatin, Hong Kong.
Shi-Hong
SH
Ma
George G
GG
Chen
Caiguo
C
Ye
Billy C S
BC
Leung
Rocky L K
RL
Ho
Paul B S
PB
Lai
D000964:Antimetabolites, Antineoplastic / Q000494:pharmacology; D017209:Apoptosis / Q000187:drug effects; D051023:BH3 Interacting Domain Death Agonist Protein / Q000378:metabolism*; D015153:Blotting, Western; D006528:Carcinoma, Hepatocellular / Q000378:metabolism* / Q000473:pathology; D002453:Cell Cycle / Q000187:drug effects / Q000502:physiology*; D045304:Cytochromes c / Q000378:metabolism; D005472:Fluorouracil / Q000494:pharmacology; D006801:Humans; D020287:In Situ Nick-End Labeling; D008113:Liver Neoplasms / Q000378:metabolism* / Q000473:pathology; D011994:Recombinant Proteins / Q000378:metabolism; D014407:Tumor Cells, Cultured
D000964:Antimetabolites, Antineoplastic; D051023:BH3 Interacting Domain Death Agonist Protein; D011994:Recombinant Proteins; D045304:Cytochromes c; D005472:Fluorouracil