Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UMLS:C0019204 (hepatocellular carcinoma)
 71,386 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

This study was performed to determine the relationship of the activation of ras and c-myc oncogenes in human hepatocellular carcinoma to the hepatitis B virus gene expression or the presence of hepatitis B virus DNA/RNA at the cellular level. This was done using immunocytochemical analysis with two different antibodies on serial sections. In addition, immunocytochemical assay for the detection of ras p21 or c-myc protein was performed in combination with in situ hybridization for hepatitis B virus DNA/RNA using 35S-labeled hepatitis B virus DNA as a probe. Investigation of a total of 14 paired human hepatocellular carcinoma and adjacent nontumorous hepatic tissues revealed enhanced expression of ras p21 in one human hepatocellular carcinoma whereas c-myc protein was found in one paired human hepatocellular carcinoma and nontumorous tissue of the same patient. Only a small proportion of human hepatocellular carcinoma cells or hepatocytes among a large number of cells on a given section showed enhanced expression, and the distribution of the oncogene product-expressing cells was focal. However, the cells overexpressing these oncogenes did not show hepatitis B surface antigen in the serial sections. Furthermore, the combined immunocytochemical and in situ hybridization assays revealed that human hepatocellular carcinoma cells overexpressing ras p21 did not show hepatitis B virus DNA/RNA, whereas some human hepatocellular carcinoma cells and nontumorous hepatocytes located away from the foci of oncogene-expressing cells gave positive signals. These findings suggest that continued expression of HBsAg or the presence of hepatitis B virus DNA/RNA in a given human hepatocellular carcinoma cell id not necessary for enhanced expression of ras or c-myc proteins.(ABSTRACT TRUNCATED AT 250 WORDS)
 ...
PMID:A lack of direct role of hepatitis B virus in the activation of ras and c-myc oncogenes in human hepatocellular carcinogenesis. 284 52

DNA was extracted from NIH 3T3 cells transformed with DNAs from human primary hepatic cancer (PHC) and Hepatoma 7402 cell line. The transformant DNA was analyzed by Southern transfer and hybridization with 32P-labeled probes of various oncogenes. The EcoRI 7.2 and 9.0 kb bands characteristic of human N-ras gene were identified in transformed NIH 3T3 cells derived both from PHC and 7402 DNA. The BamHI 6.6 kb band characteristic of human c-Ha-ras I was present only in 7402 transformants, but not in PHC transformants. Using 35S-methionine incorporation, immunoprecipitation with anti-p21 monoclonal antibodies, SDS-PAGE and autoradiography, it was demonstrated that p21 synthesis was remarkably enhanced in 7402 cells as well as in transformed cells derived from both 7402 and PHC DNA. Taking the data together, it strongly implies that N-ras is one of the transforming genes for human liver cancer.
 ...
PMID:Identification of human N-ras as the common oncogene in NIH 3T3 cells transformed with DNAs from human primary hepatic cancer and hepatoma 7402 line. 301 22

Expression of the ras oncogene p21 product by hepatocytes of cirrhotic liver with hepatocellular carcinoma (HCC) was examined immunohistochemically using mouse monoclonal antibody RAP-5. At the concentration of antibody used, histologically normal liver tissues were negative for p21 antigen, whereas hepatocytes of cirrhotic nodules from 80 of 92 HCC patients (87.4%), and 10 of 32 patients without HCC (59.4%) were positive. This difference was statistically significant (p less than 0.05). The incidence of p21 expression by hepatocytes was significantly higher in macronodular cirrhotic patients than in those with micronodular cirrhosis (p less than 0.05) and tended to be higher in those positive for hepatic hepatitis B virus markers than in those that were negative (p less than 0.1). All 16 patients with liver cell dysplasia, and 17 of 18 with adenomatous hyperplasias showed increased expression of p21 antigen. In HCC it was detected on tumor cells of 63 of 101 patients (62.4%). Characteristically, its expression in well-differentiated HCC was mild and uniformly diffuse, and in moderately differentiated tumors was markedly heterogeneous in both intensity and distribution, whereas no expression was observed in cells of poorly differentiated HCC. These observations suggest that elevated ras p21 antigen expression is important in the development of both cirrhotic nodules and HCC, but that after tumor development, its sustained elevation is no longer necessary for cell proliferation and progression through the grades of anaplasia.
 ...
PMID:Immunohistochemical detection of ras oncogene p21 product in liver cirrhosis and hepatocellular carcinoma. 303 55

We have carried out photoaffinity labeling of the ras p21 protein, a ras oncogene product, with [alpha-32P]GTP. Based on our studies, a sensitive, rapid, and specific assay for the detection of multiple forms of ras p21 has been developed. The specificity of this protocol is shown by (a) sensitivity of affinity labeling of ras p21 to known inhibitors of GTP binding and (b) immunoprecipitation of affinity labeled protein with anti-ras p21 serum. Detection and semiquantitation of ras p21 by this method is accomplished in less than 24 h and requires as little as 100,000 cells or about 5 mg of tissue sample from skin tumor, liver, and mammary tumor tissues. Furthermore, using this approach, we were able to detect the selective loss of one species of ras p21 in transplanted Morris hepatoma cells.
 ...
PMID:An affinity labeling of ras p21 protein and its use in the identification of ras p21 in cellular and tissue extracts. 354 89

The cell of origin of hepatocellular carcinoma (HCC) is controversial. A method for marking cells of different lineages in vivo and then determining their carcinogenic potential should resolve this issue. A retroviral vector expressing activated ras and beta-gal genes (Ras-gal) was transferred into adult rat hepatocytes in vivo, and some animals were treated with diethylnitrosamine (DEN). Bile ductule cells and the putative stem cells of the liver (the oval cells) did not appear to be transduced by this method. At 1 month after transfer, 5-bromo-4-chloro-3-indolyl-beta-D-galactopyranoside staining was performed on transduced rat livers to determine the blue cluster size. Eight % of the clusters in Ras-gal-transduced, DEN-treated livers contained at least twice as many cells as the largest cluster in Ras-gal-transduced, DEN-untreated rats, demonstrating that they had acquired markedly abnormal growth properties. When the retroviral vector containing beta-gal without ras (Gal-509) was transferred into DEN-treated rats, 2.5% of the cells were present in clusters containing at least twice as many cells as the largest cluster in Gal-509-transduced, DEN-untreated animals. Thus, p21-ras may increase the percentage of cells that acquire mutations in response to DEN, or it may behave synergistically with other mutations to increase the replication rate of cells. Occasional foci in Ras-gal-transduced, DEN-treated rats had extramedullary hematopoiesis. Forty % of the Ras-gal-transduced, DEN-treated rats developed unifocal HCC, mixed HCC/cholangiocarcinoma (CC), or CC at 3-6 months after transduction, suggesting that hepatocytes can develop into HCC or CC if sufficient genetic alterations occur.
 ...
PMID:Ras-transduced diethylnitrosamine-treated hepatocytes develop into cancers of mixed phenotype in vivo. 758 83

The recently cloned protein, p21 (WAF1/CIP1) is a downstream effector of p53, and mediates growth arrest by inhibiting the action of G1 cyclin-dependent kinases. Since cellular differentiation is frequently characterized by G1 arrest, we examined whether p21 upregulation occurs in differentiation. We show that p21 expression is triggered by multiple differentiation-inducing agents in hematopoietic and hepatoma cells through a p53-independent pathway. The dramatic rise in p21 levels occurs as an immediate early response to differentiation inducers. The induction of p21 is coupled to the expression of early differentiation markers, and is uncoupled from apoptosis. Finally, evidence is presented that p21 expression is uncoupled from G1 arrest in the presence of deregulated c-myc.
 ...
PMID:Induction of p21 (WAF-1/CIP1) during differentiation. 793 67

One of the major antecedent factors preceding the development of hepatocellular carcinoma is chronic hepatitis B virus infection. Also, recent molecular studies have shown that activation of c-oncogenes might be responsible for the malignant transformation in some cases of hepatocellular carcinoma. We used immunohistochemical methods to investigate the correlation of ras and c-myc oncogene expression with the presence of HBsAg in human liver disease. Our material consisted of 23 chronic active hepatitis B needle liver biopsies and surgical specimens from 11 cases of cirrhosis, 23 hepatocellular carcinoma and 10 normal adult livers. Direct, three-step and streptavidin-biotin-complex immunoperoxidase techniques using polyclonal (anti-HBsAg) and monoclonal antibodies (anti-ras p21, anti-myc p62), were performed. Normal liver tissues were negative for all antibodies used. In HBsAg+ chronic active hepatitis B cases enhancement of c-myc, and less frequently of ras oncogene expression, was a common observation. Increased myc p62 and ras p21 expression was a finding not restricted to HBsAg+hepatocytes, which occasionally were negative for oncoprotein immunostaining. All HBsAg-chronic active hepatitis B cases were negative for ras p21 and myc p62 specific staining. Cirrhotic livers showed more frequently enhanced c-myc expression. Most of the immunostained cells were negative for HBsAg. HBsAg- cases of hepatocellular carcinoma more often showed ras p21 than myc p62 overexpression. HBsAg+ hepatocellular carcinomas presented only ras p21-positive immunostaining, which was not detected in HBsAg+ hepatocytes. Our recent data supports the view that continued expression of HBsAg in human liver disease is not necessary for the enhancement of ras and c-myc oncogene expression.
 ...
PMID:Expression of ras and c-myc oncoproteins and hepatitis B surface antigen in human liver disease. 846 26

Rat ascites hepatoma cell (MM1) invade a mesothelial cell monolayer in vitro in assay medium containing serum, but not in serum-free medium. Serum could be completely replaced by 1-oleoyl lysophosphatidic acid (LPA) in inducing invasion. LPA-induced invasion was inhibited by genistein, a tyrosine-kinase inhibitor. Protein tyrosine phosphorylation in response to LPA was thus analyzed in order to determine the molecular mechanism of invasion. LPA of invasion-inducible concentrations evoked a transient increase in tyrosine phosphorylation, mainly of 110- to 130-kDa proteins in MM1 cells but not in mesothelial cells. These concentrations of LPA were over 10 times higher (10 to 25 micron) than those necessary to produce a variety of biological actions, such as tyrosine phosphorylation in fibroblasts, neurite retraction and platelet aggregation. Protein tyrosine phosphorylation and invasion by MM1 cells induced by LPA are largely regulated by rho p21, because both were inhibited by Clostridium botulinum C3 exo-enzyme, which is known to specifically inactivate rho p21. Invasion of MCL by MM1 cells induced by serum and that by B16FE7 cells induced by LPA were inhibited by genistein or C3 as well. By immunoprecipitation, we detected p 125 focal adhesion kinase (FAK) as a major protein of 110- to 130-kDa tyrosine phosphorylated in response to LPA. Tyrosine phosphorylation of paxillin by LPA was also detected.
 ...
PMID:rho-Mediated protein tyrosine phosphorylation in lysophosphatidic-acid-induced tumor-cell invasion. 859 14

Identification of gene products exclusively or abundantly expressed in hepatocellular carcinoma (HCC) and in normal liver may yield novel tumor markers. We have isolated 36 up- and down-regulated cDNAs from diethylnitrosamine-induced rat hepatocellular carcinoma and normal liver tissue by using the subtraction-enhanced display technique. Nucleotide sequence analysis revealed that the majority of 20 subtraction-enriched cDNA fragments were well-characterized oncogenes and tumor-associated genes, like c-myc, alpha-prothymosin, p21, glutathione-S transferase (G-ST) and alpha 1-acid glycoprotein (AGP). As demonstrated by Northern blot detection, all of them were preferentially expressed either in HCC or in normal liver (2- to 7-fold). As paradigm, G-ST and AGP were shown to be exclusively overexpressed in tumor nodules by in situ hybridization. In addition, 14 of the remaining 16 novel genes were analysed on Northern blot, 10 of which were differentially expressed in HCC.
 ...
PMID:Isolation of up- and down-regulated cDNAs associated with hepatocellular carcinoma by a subtraction-enhanced display technique. 861 55

Phthalate esters such as di(2-ethylhexyl)phthalate (DEHP) either promote or inhibit rat liver tumorigenesis depending on the carcinogenesis protocol. In this study, we examined the expression of two histochemical markers, the tumor associated isozyme of aldehyde dehydrogenase (ALDH-3) and the oncoprotein p21 Ras, in the livers of male F344 rats. The rats were initiated with DEN and further treated with either DEHP (a known inhibitor of hepatocarcinogenesis), phenobarbital (PB, a known promoter of hepatocarcinogenesis), or a combination of DEHP and PB. The studies were designed to examine the expression of these markers in both normal appearing liver and hepatic hyperplastic and neoplastic lesions and to correlate the early expression of the markers at 26 weeks in the normal appearing liver to later tumor incidence at 52 weeks. The expression of each marker was detected by immunohistochemical methods on formalin-fixed paraffin embedded sections of normal appearing liver or liver lesions. We found that ALDH-3 and p21 expression were significantly enhanced in rats receiving PB after DEN initiation at 26 weeks and that the incidence of hepatocellular carcinomas was likewise increased compared to control or DEN only treated animals. DEN initiation followed by a combination of PB and either 0.1 or 0.5% DEHP significantly reduced ALDH-3 but not p21 Ras expression at 26 weeks compared to DEN plus PB only. These treatment regimens also reduced the incidence of hepatocellular carcinomas at 52 weeks. DEN followed by any of the three doses of DEHP without PB resulted in ALDH-3 expression similar to DEN alone. However, p21 Ras expression was significantly increased after these treatments. For all treatment groups, both the early (26 weeks) expression of p21 Ras and ALDH-3 correlated with hepatocellular carcinoma incidence at 52 weeks. However, the correlation between hepatocellular carcinoma and ALDH-3 expression was better than p21 Ras or the other markers we have studied. We concluded that ALDH-3 expression is significantly downregulated after DEHP treatment, and that expression of the isozyme correlated with later hepatocarcinoma incidence and may indicate a significant relationship between ALDH-3 expression and hepatocarcinogenesis during DEHP treatment.
 ...
PMID:Hepatocyte expression of tumor associated aldehyde dehydrogenase (ALDH-3) and p21 Ras following diethylnitrosamine (DEN) initiation and chronic exposure to di(2-ethylhexyl)phthalate (DHEP). 876 21


<< Previous 1 2 3 4 5 6 7 8 9 10 Next >>