Apoptosis of human colon carcinoma HT-29 cells induced by ceramide

AIM： To investigate the effect of exogenous ceramideinduced apoptosis on human colon carcinoma HT-29 cells. METHODS： Light microscope, transmission electron microscope and fluorescence microscope were used to observe the morphology change of apoptosis in HT-29 cells. Agarose gel electrophoresis was performed to detect the DNA fragment. Mitochondrial function was detected by MTT assay, mRNA expression of Bcl-2 family gene members was determined by reverse transcription polymerase chain reaction （RT-PCR） assay. RESULTS： After C2-ceramide treatment, typical characteristics of apoptosis, such as nuclear chromatin breakage, apoptotic body and DNA ladder, could be observed. After exposure to 50μmol/L C2-ceramide for 12 and 24 h, cell apoptosis was 64.1% and 81.3% respectively, which had a time-and dose-effect relationship. Mitochondrial function started to decrease from 6 h after exposure to ceramide. Meanwhile, ceramide up-regulated or down-regulated the mRNA expression of Bcl-2 family gene members. CONCLUSION： Ceramide induces apoptosis of human colon carcinoma HT-29 cells by affecting the expression of Bcl-2 family gene members and impacting the mitochondrial function.

Guggulsterone induces apoptosis of human hepatocellular carcinoma cells through intrinsic mitochondrial pathway

AIM: To investigate the effects of guggulsterone on the proliferation and apoptosis of human hepatoma Hep G2 cells in vitro and relevant mechanisms.METHODS: Human hepatocellular carcinoma Hep G2 cells and normal human liver L-02 cells were treated with different concentrations of guggulsterone(5-100 μmol/L) for 24-72 h. Cell proliferation was tested by MTT assay. Cell cycle and apoptosis were investigated using flow cytometry(FACS). Bcl-2 and Bax m RNA and protein expression was detected by real-time PCR and Western blot, respectively. TGF-β1, TNF-α, and VEGF contents were determined by ELISA.RESULTS: Guggulsterone significantly inhibited Hep G2 cell proliferation in a dose- and time-dependent manner. FACS showed that guggulsterone arrested Hep G2 cell cycle at G0/G1 phase. Guggulsterone induced apoptosis was also observed in Hep G2 cells, with 24.91% ± 2.41% and 53.03% ± 2.28% of apoptotic cells in response to the treatment with 50 μmol/L and 75 μmol/L guggulsterone, respectively. Bax m RNA and protein expression was significantly increased and Bcl-2 m RNA and protein expression was decreased. ELISA analysis showed that the concentrations of TGF-β1 and VEGF were significantly decreased and TNF-α concentration was increased.CONCLUSION: Guggulsterone exerts its anticancer effects by inhibiting cell proliferation and inducing apoptosis in Hep G2 cells. Guggulsterone induces apoptosis by activation of the intrinsic mitochondrial pathway.

Growth Inhibition Effect of Parthenolide on Human Hepatocellular Carcinomacell Line BEL-7402

To study the effects of parthenolide on human hepatocellular carcinoma cell line BEL-7402 and explore its possible mechanism, human hepatocellular carcinoma cell line BEL-7402 was cultured in vitro and treated with parthenolide of different concentrations. Cells without addition of parthenolide were used as control. The growth of inhibition of cells induced by various concentrations was analyzed by using the MTT assay. The morphologic changes of apoptosis was observed under an inversion microscope by Giemsa staining. The expression levels of PCNA albumen were measured by means of immunohistochemical methods. Parthenolide can inhibit the proliferation of BEL-7402 cells in vitro in adose-dependent manner. Apoptosis with nuclear chromatin condensation, fragmentation and cell shrinkage were found by means of inversion microscopy. Formation of apoptotic bodies was observed by Giemsa staining. The immunohistochemical results show that the expression of PCNA has been decreased. Parthenolide can inhibit the tumor growing of BEL-7402 cells, and induce the apoptosis of cells. The mechanisms of those functions may be via inhibiting the expression of PCNA.

Diversity of Gene Expression in Hepatocellular Carcinoma Cells

Understanding tumor diversity has been a long-lasting and challenging question for researchers in the field of cancer heterogeneity or tumor evolution. Studies have reported that com- pared to normal cells, there is a higher genetic diversity in tumor cells, while higher genetic diversity is associated with higher progression risks of tumor. We thus hypothesized that tumor diversity also holds true at the gene expression level. To test this hypothesis, we used t-test to compare the means of Simpson＇s diversity index for gene expression （SDIG） between tumor and non-tumor samples. We found that the mean SDIG in tumor tissues is significantly higher than that in the non-tumor or normal tissues （P 〈 0.05） for most datasets. We also combined microarrays and next-generation sequencing data for validation. This cross-platform and cross-experimental validation greatly increased the reliability of our results.