Effect of bax, bcl-2 and bcl-xL on regulating apoptosis in tissues of normal liver and hepatocellular carcinoma

Expression of Bcl-2/Bax, Bak and hepatocytic apoptosis in tissues of patients with hepatitis D

AIM: To study the expression of Bcl-2, Bax, Bak and hepatocytic apoptosis in pathogenesis of hepatitis D.

METHODS: Expression of HDAg, Bcl-2, Bax, Bak and hepatocytic apoptosis in liver tissues of 77 patients with hepatitis D were studied by immunohistochemistry and terminal deoxynucleotidyl transferase-mediated dUTP nick end labelling (TUNEL) technique. Meanwhile, the relationship between expression of HDAg, Bcl-2/Bax and hepatocytic apoptosis were studied by double labeling and serial sections.

RESULTS: Bcl-2 was mainly expressed in the cytoplasm of hepatocytes, Bax and Bak mainly in the cytoplasm of hepatocytes and partly in the nucleus of hepatocytes, and HDAg mainly in the nucleus of hepatocytes. Many HDAg and Bax or Bak positive cells were distributed among infiltrating lymophocytes at the periportal region especially at the advancing edges in the areas of piecemeal necrosis. Many apoptotic hepatocytes were found to locate near to positive cells of HDAg. There were positive correlations between degrees of HDAg expression, Bax or Bak expression, and hepatocytic apoptosis (t = 27.89, P < 0.01, P < 0.05 t = 19.16, P < 0.05 t = 18.22).

CONCLUSION: The distribution and expression of Bax, Bak, HDAg and hepatocytic apoptosis are significantly correlated with the activity of imflammation and the severity of the liver damage.

Expression of HSP 70 and caspase 3 and their significance in hepatocellular carcinoma tissues

AIM: To investigate the expression of heat shock protein 70 (HSP70) and caspase 3 protein and their clinical significance in hepatocellular carcinomas and surrounding liver tissues.

METHODS: The expression of HSP70 and caspase 3 protein were detected by immunohistochemistry in hepatocellular carcinomas (HCC) and their surrounding liver tissues.

RESULTS: The positive rate and intensity of HSP70 in HCCs were significantly higher than those in pericarcinomatous liver tissues (68.6% vs 31.4%, P < 0.01), and these of caspase protein were significantly lower (17.1% vs 35.7%, P < 0.01). The expression level of HSP70 and caspase protein in HCCs was remarkably related to differentiation degree and tumor size of HCCs, and the poorer differentiation, the stronger the expression of HSP70 (F = 5.219 and 5.421 respectively, P < 0.01), the weaker the expression of caspase 3 protein (F = 5.944 and 4.571 respectively, P < 0.01). The correlation analysis indicated that there was a negative relationship between expression of HSP70 and caspase protein in HCC and their surrounding liver tissues (r = 0.4 126 and 0.5 237 respectively, P < 0.01).

CONCLUSION: The expression of HSP70 may make uncontrolled growth and unceasingly increased malignant degree of HCC by accelerating cell transformation and proliferation and inhibiting apoptosis. HSP70 may be an important marker for evaluation of prognosis in patients with HCC.

Effect of oncogenes on differentiation and transformation of rat oval cells

AIM: To study the effects of oncogenes on differentiation and transformation of oval cells by detecting and characterizing the expression of AFP and Ha-ras, c-myc genes of rat oval cells in vitro.

METHODS: Proliferation of rat oval cells was induced by chemical carcinogen, 3'-Me-DAB. By using Percoll density gradient centrifugation method, oval cells were isolated,followed by continous cultivation in vitro. The expression of Ha-ras and c-mycgenes and AFP in the oval cells from cultures was dynamically observed by RNA-DNA slot blot hybridization and flow cytometry.

RESULTS: The expression of AFP and Ha-ras, c-myc genes in the cultured oval cells from different phases was synchronous: At the beginning of oval cell cultivation in vitro, both of AFP and oncogenes displayed a higher level expression and then declined. Up to 20th passage, the expression of AFP and oncogenes went up again and then kept a lower level. To 65th passage, the oval cells not only presented a growth rate increased, population doubling time shortened, adiploid chromosomes and growing on soft agar, but also the expression of oncogenes and AFP went up again.

CONCLUSION: Oncogenes and their products participate not only in the regulation of cellular transformation, but also in the process of cell differentiation.

Isolation of a novel member of small G protein superfamily and its expression in colon cancer

AIM: APMCF1 is a novel human gene whose transcripts are up-regulated in apoptotic MCF-7 cells. In order to learn more about this gene’s function in other tumors, we cloned its full length cDNA and prepared its polyclonal antibody to investigate its expression in colon cancers with immunohistochemistry.

METHODS: With the method of 5’ rapid amplification of cDNA end (RACE) and EST assembled in GenBank, we extended the length of APMCF1 at 5’ end. Then the sequence encoding the APMCF1 protein was amplified by RT-PCR from the total RNA of apoptotic MCF-7 cells and cloned into the prokaryotic expression vector pGEX-KG to construct recombinant expression vector pGEX-APMCF1. The GST-APMCF1 fusion protein was expressed in E. coli and used to immunize rabbits to get the rabbit anti-APMCF1 serum. The specificity of polyclonal anti-APMCF1 antibody was determined by Western blot. Then we investigated the expression of Apmcf1 in colon cancers and normal colonic mucosa with immunohistochemistry.

RESULTS: A cDNA fragment with a length of 1745 bp was obtained. APMCF1 was mapped to chromosome 3q22.2 and spanned at least 14.8 kb of genomic DNA with seven exons and six introns contained. Bioinformatic analysis showed the protein encoded by APMCF1 contained a small GTP-binding protein (G proteins) domain and was homologous to mouse signal recognition particle receptor β(SRβ). A coding region covering 816 bp was cloned and polyclonal anti-APMCF1 antibody was prepared successfully. The immunohistochemistry study showed that APMCF1 had a strong expression in colon cancer.

CONCLUSION: APMCF1 may be the gene coding human signal recognition particle receptor β and belongs to the small-G protein superfamily. Its strong expression pattern in colon cancer suggests it may play a role in colon cancer development.

In situ quantitative study of BAG-1 and BAD in extrahepatic cholangiocarcinoma

AIM

To detect the expression of apoptosis related proteins BAG-1 and BAD and to investigate their functions of apoptosis modulation and relations to tumor differentiation in extrahepatic cholangiocarcinoma.

METHODS

Quantitative in situ methods of DAKO EnvisionTM Systems immunohistochemistry in combination with computer-assisted image analysis and apoptotic cells counting were used to observe the expression levels of BAG-1 and BAD and the apoptosis indexes in 42 cases of extrahepatic cholangiocarcinoma.

RESULTS

The expression levels of BAG-1 and BAD were measured with average absorbance (A) derived from the quantitative image analysis. Among 24, 13 and 5 cases of well, moderately and poorly differentiated extrahepatic cholangiocarcinomas, the average A of BAG-1 was respectively 0.068±0.037, 0.112±0.057 and 0.152±0.062, of BAD was respectively 0.079±0.053, 0.138±0.058 and 0.165±0.061, and the apoptotic indexes examined in the hematoxylin-and-eosin-stained specimens were respectively 1.1±0.5, 1.7±0.3 and 3.5±1.3. The expression levels of BAG-1 and BAD and the apoptotic indexes were increased obviously from well, moderately to poorly differentiated extrahepatic cholangiocarcinoma (P<0.05). The expression level of BAD was correlated to the apoptotic indexes (P<0.01).

CONCLUSION

Expressions of BAG-1 and BAD and apoptosis indexes were all associated with differentiation of extrahepatic cholangiocarcinoma. BAG-1 and BAD may take part in the apoptosis modulation of the tumor.

Expressive characteristic and biological significance of oncogenes during rat hepatocarcinogenesis

AIM

To explore the expressive characteristic and biological significance of oncogenes during experimental hepatocarcinogenesis in rat.

METHODS

A rat model of liver carcinoma was induced with carcinogen 3-Me-DAB. The hepatic expressive characteristic of Ha-ras, c-myc and Ki-ras rats in varied stages in induction of cancer were examined with in situ hybridization and RNA slot blot hybridization.

RESULTS

The hepatic expression and distribution of Ha-ras and c-myc were similar in different periods of cancer induction. In early stage of carcinoma induction, there were more positive cells of Ha-ras and c-myc but little Ki-ras positive cells. In late stage of carcinoma induced, the number of positive cells of three oncogenes was decreased; On the 17th week of induction of cancer, the signals of three oncogenes in all the cancer nodules were negative or weak but stronger in hepatic peri-cancer tissues.

CONCLUSION

Oncogenes Ha-ras and c-myc were activated and had synergistic effect on the malignant transformation of cells in early stage of hepatocarcinogenesis. Ki-ras might be activated in late stage of hepatocarcinogenesis and associated with malignant transformation of hepatocytes.

Effect of arsenic trioxide on rat hepatocarcinoma and its renal cytotoxicity

AIM: To study the effect of arsenic trioxide (As₂O₃) on rat experimental hepatocarcinoma and its renal cytotoxicity.

METHODS: The hepatocarcinoma model was established by diethaylnitrosamine perfusion in stomach of 120 Wistar rats, and the treatment began at the end of 20 weeks. Before the treatment, the rat models were randomly divided into 5 groups. In the treatment groups, three doses of As₂O₃ were injected into rat abdominal cavity, the total time of drug administration was 4 weeks. Cisplatin control or the blank group was injected into abdominal cavity with equal amount of cisplatin or saline at the same time, respectively. On the 7^th, 14^th and 28^th day after the treatment, the hepatocarcinoma nodules were obtained and the morphologic changes of hepatocarcinoma cells were observed under light and electron microscopes; Immunohistochemistry (S-P methods) was employed to detect the expression of bcl-2, bax and PCNA in hepatocarcinoma tissues; flow cytometry (TUNEL assay) was used to detect the apoptosis of liver cancer cells and the change of cytokinetics. On the 28^th day, the kidneys were obtained and their histologic changes were observed under light microscope, and immunohistochemistry (SP stain) was also employed to detect the expression of bcl-2 and PCNA. Cisplatin and saline solution were used as the control.

RESULTS: As₂O₃ could induce the apoptosis of rat liver cancer cells and exhibited typical morphologic changes. The incidence of apoptosis of hapatocarcinoma cells was elevated (P = 0.001). The elevation was the most higher in the group of middle-dose of As₂O₃ (1 mg·kg^-1), significantly higher than that of the other arsenic groups and the controls (P = 0.001). Large dose of As₂O₃ (5 mg·kg^-1) was able to arise the incidence of apoptosis, but also produced a large amount of necrosis and inflammatory reaction. Middle dose of As₂O₃ dramatically increased the cell number in G2/M phase (P = 0.0001), and apoptosis happened apparently. The expression of bcl-2 and bax was related to the dose of As₂O₃. With the up-regulation of apoptotic incidence, the ratio of bcl-2/bak decreased. But the incidence of apoptosis was not the highest status and the ratio of bcl-2/bax was at the lowest when the highest-dose of As₂O₃ was used. There was significant difference among the PCNA indexes (PCNA L1) of the five groups. Of them, three arsenic groups all showed decrease of different degrees, and this down-regulation was most obvious in group A. There was significant difference among the three groups (P = 0.016). Under the light microscope, the rat kidney in the cisplatin group exhibited tubular epithelium swelling and degeneration, protein casts in collecting tubules; While all arsenic groups didn’t show the significant changes (P = 0.013). In the arsenic groups, the expression of bcl-2 in the renal tubular epithelium was increased (P = 0.005), no obvious changes happened to PCNA L1. But in the group of cisplatin, the PCNA L1 increased significantly (P = 0.001).

CONCLUSION: As₂O₃ can induce apoptosis of rat hepatocellular carcinoma cells. And there is optimum dose; too high dose will induce the cytotoxic effect, while certain dose of As₂O₃ is able to block the cell cycle at G2/M phase. As₂O₃ had the most remarkable influence on G2/M cells, and it can also induce apoptosis to cells at other phases. As₂O₃ can restrain the proliferation of rat hepatocellular carcinoma cells, in a dose-time dependent manner. Compared with cisplatin, As₂O₃ didn’t show obvious renal toxicity, which was related to the increasing expression of bcl-2 in renal tubular epithelium, the inhibition of apoptosis and the anti-oxidation effects.

Expression of survivin protein in hepatocellular carcinoma tissues and its relationship with clinical pathological features and prognosis

AIM

To investigate the expression of survivin protein in human hepatocellular carcinoma (HCC) and its relationship with clinical features and prognosis of patients with HCC.

METHODS

The expression of survivin protein and the proliferation of tumor cells marked by PCNA in 48 cases of HCC were assessed by immunohistochemical method. TUNEL method was used to detect apoptosis.

RESULTS

The survivin protein was expressed in 31 of 48 cases of HCC (64.6%). Expression of survivin protein was significantly higher in those of Edmondson grade Ⅲ-Ⅳ than in those of grade Ⅰ-Ⅱ (88.0% vs 39.1%, P = 0.013). The ratio of proliferative index to apoptotic index was significantly higher in HCC with positive survivin expression than that with negative survivin expression (1.8 vs 1.1, P = 0.045). The survival rate of three years of patients with positive survivin expression was significantly lower than that of patients with negative survivin expression (70.6% vs 35.5%, P = 0.011).

CONCLUSION

The expression of survivin may play an important role in breaking the balance of proliferation and apoptosis of HCC cells and is closely associated with prognosis of patients with HCC.