Synergistic effect of rapamycin (RPM) and PD98059 on cell cycle and mTOR signal transduction in human colorectal cancer cells / 中华肿瘤杂志

<p><b>OBJECTIVE</b>To investigate the synergistic effect of rapamycin (RPM) and PD98059 on human colorectal cancer cells and its potential mechanisms.</p><p><b>METHODS</b>Three human colorectal cancer cell lines SW480, HCT116 and HT29 were treated with RPM 10 nmol/L, PD98059 (10 micromol/L, 20 micromol/L, 40 micromol/L, 50 micromol/L), or RPM plus PD98059, respectively, and the sensitivity was analyzed by MTT assay. The cell cycle progression was evaluated by flow cytometry. Western blotting analysis was performed to examine the total and phosphorylated levels of mammalian target of rapamycin (mTOR) and its downstream translational signaling intermediates, 70 kDa ribosomal protein S6 kinase (p70s6k) and eukaryotic initiation factor 4E-binding protein 1 (4E-BP1).</p><p><b>RESULTS</b>Both RPM and PD98059 could inhibit viability of the three cell lines. The anti-proliferative effect of PD98059 exhibited a time/dose dependent manner and was strengthen by RPM. All the treatment with RPM, PD98059, and RPM + PD98059 induced arrest of cell cycle, although the arrest was confined at different cell cycle phases. In addition to their effect on proliferation and cell cycle, both inhibitors also reduced phosphorylation levels of mTOR, p70s6k, and 4E-BP1, as well as total 4E-BP1 levels in SW480 and HCT116 cells. That effect was reinforced when cells were treated with RPM plus PD98059 simultaneously, whereas total protein levels of mTOR and p70s6k remained unchanged.</p><p><b>CONCLUSION</b>RPM and PD98059 inhibit proliferation of colorectal cancer cells synergistically, and induce cell cycle arrest. The modulation of mammalian target of rapamycin signaling pathway is involved in its potential mechanisms.</p>

The relationship of mTOR signaling pathway and histone acetylation in human gastric cancer cell lines / 中华医学遗传学杂志

<p><b>OBJECTIVE</b>To evaluate the relationship between mammalian target of rapamycin (mTOR) signaling pathway and histone acetylation in cell survival, cell cycle, gene expression and protein level on human gastric cancer cells.</p><p><b>METHODS</b>Human gastric cancer cell lines, MKN45 and SGC7901 were treated with trichostatin A, rapamycin and/or LY294002, a PI3K inhibitor. Cell viability was analyzed by methylthiazolyl tetrazolium. Cell cycle distribution was evaluated by flow cytometry. The transcription level of p21(WAF1) gene was detected by using real-time polymerase chain reaction. Proteins were detected by Western blotting.</p><p><b>RESULTS</b>Cell viability remarkably reduced after treatment by more than two drugs (P< 0.01). Through flow cytometry assessment, MKN45 cells were arrested in G2 phase (P< 0.05), while SGC7901 cells were in G2 or G1 phase (P< 0.05) whether treated with single or more than two drugs. The expression of p21(WAF1) mRNA was remarkably increased in the gastric cancer cells treated with conjoined drugs (P< 0.01). Phosphorylation of Akt, p70S6K and 4E-BP1 was significantly reduced in cells treated with conjoined drugs (P< 0.01). And histone acetylation of H4/H3 was also increased in cells treated with conjoined drugs (P< 0.01).</p><p><b>CONCLUSION</b>mTOR singnaling pathway has an important relationship with histone acetylation in gastric cancer cell lines. There is a co-effect of mTOR inhibitor and histone deacetylase inhibitor on gastric cancer cells.</p>

The effect of PKC-delta inhibitor Rottlerin on human colon cancer cell line SW1116 and its mechanism / 中华肿瘤杂志

<p><b>OBJECTIVE</b>To evaluate the effect of PKC-delta inhibitor Rottlerin on human colon cancer cells and its mechanism.</p><p><b>METHODS</b>Human colon cancer cell line SW1116 cells were treated with Rottlerin. The transcriptional level of DNA methyltransferase (Dnmt)1, Dnmt3a and Dnmt3b was detected by real-time RT-PCR. Cell cycle distribution was evaluated by flow cytometry (FCM). In addition, cellular morphological changes were examined by light microscopy.</p><p><b>RESULTS</b>PKC-delta inhibitor decreased the expression of Dnmt1, Dnmt3a mRNA, up-regulated APC, p21(WAF1) and p16(INK4A) mRNA. Demonstarted by flow cytometry, Rottlerin increased the percentage of cell cycle G0/G1 phase cell numbers (P = 0.02) and decreased the percentage of cell cycle G2/M phase cell numbers (P = 0.01). Remarkable changes of cellular morphology were observed under light microscope: The volume and cytoplasm of cells treated with Rottlerin were increased. The cell contour was not very clear, and mitotic figures were less frequently seen.</p><p><b>CONCLUSION</b>PKC-delta inhibitor Rottlerin inhibites cell division and proliferation of the colon cancer SW1116 cells through regulating DNA methylation and blocking the signaling pathway of mitogen-activated protein kinase (MAPK).</p>

Effect of eukaryotic expression plasmid containing methylenetetrahydrofolate reductase gene on transcriptional level of tumor-related genes in human gastric cancer cell line / 中华消化杂志

Objective To analyze the effect of eukaryotic plasmids containing wild (sense) or anti- sense methylenetetrahydrofolate reductase (MTHFR) gene on cell viability and transcription level of tumor related genes in human gastric cancer cell line.Methods Human gastric cancer cell line MKN-45 was cultured.Recombinant plasmids containing wild MTHFR (W) or antisense MTHFR (A) gene, pCMV-W and pCMV-A,were constructed.Then pCMV-W,pCMV-A and pCMV blank plasmid were transfected into MKN45 cells respectively by using lipofect.Cell viability was analyzed by 3-(4,5-bime- thylthiazolyl-2)-2,5-diphenyhetrazolium dromide(MTT).The transcription levels of Dnmt 1,c-myc, p21~(WAF1) and hMLH1 genes were detected by real-time polymerase chain reaction(PCR).Results Cell vi- ability remarkably increased in those transfected with wild MTHFR (P＜0.01),which was contrary to those transfected with antisense MTHFR(P＜0.01).The expression of those tumor related genes mRNAs were all remarkably decreased in the MKN45-W cells in comparison with those in the MKN45-pCMV cells.No significant difference in the expressions of those tumor related genes mRNAs were found between the MKN45 cells transfected with pCMV-A and blank pCMV.Conclusion MTHFR influences cell viability and the expres- sion level of tumor related genes in human gastric cancer cell line MKN45.