Expression of liver cancer associated gene HCCA3

ADD66, a gene involved in the endoplasmic reticulum-associated degradation of alpha-1-antitrypsin-Z in yeast, facilitates proteasome activity and assembly

Antitrypsin deficiency is a primary cause of juvenile liver disease, and it arises from expression of the "Z" variant of the alpha-1 protease inhibitor (A1Pi). Whereas A1Pi is secreted from the liver, A1PiZ is retrotranslocated from the endoplasmic reticulum (ER) and degraded by the proteasome, an event that may offset liver damage. To better define the mechanism of A1PiZ degradation, a yeast expression system was developed previously, and a gene, ADD66, was identified that facilitates A1PiZ turnover. We report here that ADD66 encodes an approximately 30-kDa soluble, cytosolic protein and that the chymotrypsin-like activity of the proteasome is reduced in add66Delta mutants. This reduction in activity may arise from the accumulation of 20S proteasome assembly intermediates or from qualitative differences in assembled proteasomes. Add66p also seems to be a proteasome substrate. Consistent with its role in ER-associated degradation (ERAD), synthetic interactions are observed between the genes encoding Add66p and Ire1p, a transducer of the unfolded protein response, and yeast deleted for both ADD66 and/or IRE1 accumulate polyubiquitinated proteins. These data identify Add66p as a proteasome assembly chaperone (PAC), and they provide the first link between PAC activity and ERAD.

Gene cloning of murine α-fetoprotein gene and construction of its eukaryotic expression vector and expression in CHO cells

AIM

To clone murine AFP gene, to construct the eukaryotic expression vector of AFP and express it in CHO cells.

METHODS

Total RNA was extracted from Hepa1-6 cells, then the murine AFP gene was amplified by RT-PCR and cloned into the eukaryotic expression vector pcDNA3.1. The recombinant vector was transformed into E.coli. DH5α, the positive clones were selected and plasmid DNA was identified by restriction enzyme analysis and sequencing. After transient transfection of CHO-K1 cells with the recombinant vector, Western blotting was used to detect the expression of AFP.

RESULTS

The 1.8 kb murine α-fetoprotein gene was successfully cloned from the total RNA of Hepa1-6 cells. Result from restrictiive enzyme analysis and sequencing showed that the murine α-fetoprotein gene was successfully inserted into pcDNA3.1. Result from Western blotting showed that the recombinant vector could express murine α-fetoprotein in CHO-K1 cells.

CONCLUSION

The successfully constructed eukaryotic expression vector of murine α-fetoprotein could provide a basis for the research of immunotherapy for hepatocellular carcinoma with pmAFP.

Expression of hsMAD2 in Human Hepatocellular carcinoma and its significance

AIM

To study the expression of hsMAD2 in primary human hepatocellular carcinoma(HCC) tissues and its significance.

METHODS

The expression of hsMAD2 was detected with immunohistochemical SABC method in 39 cases of HCC tissue and 26 cases of liver cirrhosis tissue and 3 cases of HCC cell lines, and the relationship between HCC pathological grade and hsMAD2 expression rate was analyzed.

RESULTS

Fifty nine percent (23/39) of HCC tissues expressed hsMAD2, the positive rate was 100% (15/15) in non-tumor liver cells adjacent to HCC and 92% (24/26) in cirrhosis tissues. No expression was found in 3 cases of HCC cell lines. There was no significant difference between pathological grade and expression rate of hsMAD2.However, there was a significant difference of expression of hsMAD2 between HCC tissues and cancerous tissues arrounding liver tissues (x²=6.888, P <0.01) and liver cirrhosis tissues(x²=8.656, P <0.01).

CONCLUSION

Expression rate of hsmad2 in HCC decreases significantly compared to surrounding liver tissues and liver cirrhosis tissues. hsMAD2 is possibly related to early pathogenesis of HCC.

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.

The analysis of γ-glutamyl transpeptidase gene in different type liver tissues

AIM: To probe the value of γ-glutamyl transpeptidase (GGT) messenger RNA in monitoring canceration of liver cells and for early diagnosis of hepatocellular carcinoma (HCC), by researching the types of GGT messenger RNA (GGTmRNA) in liver tissues and peripheral blood of different hepatopathy.

METHODS: The three types of GGTmRNA (A, B, C) in liver tissues and peripheral blood from the patients with HCC, noncancerous hepatopathy, hepatic benign tumor, secondary carcinoma of liver, and healthy persons were detected by reverse-transcription polymerase chain reaction (RT-PCR).

RESULTS: (1) In normal liver tissues, type A was predominantly found (100.00%), type B was not found, type C was found occasionally (25.00%); (2) The distribution of types of GGTmRNA in liver tissues with acute hepatitis, chronic hepatitis, cirrhosis, alcoholic hepatopathy was similar as in normal liver tissues (P > 0.05), but type B was found in 3 of 18 patients with chronic hepatitis (16.67%), and also in 3 of 11 patients with cirrhosis (27.27%); (3) There was no significant difference of types of GGTmRNA between liver tissues with hepatic benign tumor, secondary carcinoma of liver and normal liver tissues (P > 0.05); (4) Type B was predominant in cancerous tissues with HCC (87.5%), the prevalence of type B in cancerous tissues was significantly higher than that in normal liver tissues (0/12) (P < 0.05), but the prevalence of type A in cancerous tissues (46.88%) was significantly lower than that in normal liver tissues (100.00%) (P < 0.05), and the prevalence of type C (6.25%) in cancerous was the same as that in normal liver tissues (25.00%) (P > 0.05). In noncancerous tissues of livers with HCC, the main types were type A and type B, the prevalence of type A (85.71%, 90.48%) and type C (14.29%, 9.52%) in noncancerous tissues of liver with HCC was similar as that in normal liver tissues (A: 100.00%; C: 25.00%) (P > 0.05), but the prevalence of type B (80.95%, 76.19%) in noncancerous tissues of livers with HCC was significantly higher than that in normal liver tissues (0/12) (P < 0.05); (5) The prevalence of type B (37.5%) in peripheral blood with HCC was higher than that in normal person (0/12) (P < 0.05). In peripheral blood, type B was found in 4 of 11 cases of HCC with serum AFP negative.

CONCLUSION: The shift of types of GGTmRNA from A to B in liver tissues may be closely related to the development of HCC, and the analysis of GGT gene may provide a useful tool for early diagnosis of HCC.

Applying a highly specific and reproducible cDNA RDA method to clone garlic up-regulated genes in human gastric cancer cells

AIM: To develop and optimize cDNA representational difference analysis (cDNA RDA) method and to identify and clone garlic up-regulated genes in human gastric cancer (HGC) cells.

METHODS: We performed cDNA RDA method by using abundant double-stranded cDNA messages provided by two self-constructed cDNA libraries (Allitridi-treated and paternal HGC cell line BGC823 cells cDNA libraries respectively). BamH I and Xho I restriction sites harbored in the library vector were used to select representations. Northern and Slot blots analyses were employed to identify the obtained difference products.

RESULTS: Fragments released from the cDNA library vector after restriction endonuclease digestion acted as good marker indicating the appropriate digestion degree for library DNA. Two novel expressed sequence tags (ESTs) and a recombinant gene were obtained. Slot blots result showed a 8-fold increase of glia-derived nexin/protease nexin 1 (GDN/PN1) gene expression level and 4-fold increase of hepatitis B virus x-interacting protein (XIP) mRNA level in BGC823 cells after Allitridi treatment for 72 h.

CONCLUSION: Elevated levels of GDN/PN1 and XIP mRNAs induced by Allitridi provide valuable molecular evidence for elucidating the garlic's efficacies against neurodegenerative and inflammatory diseases. Isolation of a recombinant gene and two novel ESTs further show cDNA RDA based on cDNA libraries to be a powerful method with high specificity and reproducibility in cloning differentially expressed genes.