Roles of EGFR-Stat3 signal pathway in carcinogenesis of experimental hepatoma in rats.

The purpose of this study is to investigate if the EGFR-Stat3 signal pathway contributes to the carcinogenesis of hepatoma in rats. Hepatoma was induced in rats by 3'Me-DAB as a model. EGFR, TGFalpha, Stat3, p-Stat3 in different stages of carcinogenesis were detected by immunohistochemistry and Western blot. In situ hybridization was applied to investigate the expression of Stat3 mRNA. The expressions of signal molecules were assessed by KS400 Image Analysis system. The data were statistically evaluated. EGFR, TGFalpha, Stat3 were highly expressed in the stages of liver necrosis and repairment. All hepatocellular carcinoma cases revealed elevated expression of EGFR, TGFalpha. Elevation of Stat3 mRNA and protein levels were identified, increase of activation of Stat3 was also observed. In HCC, there was positive correlation between p-Stat3 level and the expression of TGFalpha and PCNA. Increased expression of Bcl-2 (P < 0.05) coincided with elevated level of p-Stat3. Therefore, the EGFR-Stat3 signal pathway was related to the development of hepatoma in rats. TGFalpha-EGFR autocrine ring formation may lead to the activation of Stat3 and in turn, promote proliferation and regulate the transcription of genes regulating cell apoptosis and cell cycle.

[Sorting of side population cells from multiple myeloma cell lines and analysis of their biological characteristics].

This study was aimed to sort the side population (SP) cells from human multiple myeloma cell lines, then detect the biological characteristics of those SP cells. After Hoechst33342 staining, intracellular Hoechst33342 fluorescence staining differences of myeloma cell lines observed by the fluorescence microscopy. The fluorescence-activated cell sorting (FACS) technology was used to isolate SP cells and main population (MP) cells; proliferative capacity in vitro was determined by cell growth curve; the cell colony forming ability was compared by colony forming test. The CD138 expression was detected by flow cytometry. The expression of ABCG2 mRNA was detected by reverse transcription PCR; CCK-8 assay and colony forming test were used to evaluate the effect of bortezomib on the cell proliferation, vitality and colony forming ability of the two populations. The results showed that the myeloma cell lines had a small proportion of SP cells, especially, RPMI 8226 cells accounted for the highest proportion of SP cells (7.10 ± 2.69)%, which have also been confirmed under the fluorescence microscope; the proliferative activity and cell colony forming ability of SP cells were significantly higher than those of MP cells (P < 0.05). The expression levels of CD138 in SP and MP cells were not significantly different (P > 0.05). RT-PCR results showed that SP cells expressed the drug-resistance gene ABCG2, but MP cells hardly express these genes. The inhibition rate of bortezomib on SP cells was significantly lower than that on MP cells (P < 0.05), however, the difference was not significant (P > 0.05) at bortezomib 40 nmol/L. Bortezomib could reduce colony formation in the both two cell populations, but more severe reduction appeared in the MP cells. It is concluded that the myeloma cell line contain a small amount of SP cells with the cancer stem cell characteristics.