Methylation status of c-fms oncogene in HCC and its relationship with clinical pathology

Abnormal localization and accumulation of FLT3-ITD, a mutant receptor tyrosine kinase involved in leukemogenesis

Aberrant subcellular localization of mutant transmembrane receptors is increasingly acknowledged as a possible mechanism for an altered signaling quality leading to transformation. There is evidence that mutated receptor tyrosine kinases of subclass III, for example the platelet-derived growth factor receptor (PDGFR) and KIT-protein, are aberrantly localized in human cancers. In order to further analyze this phenomenon, we investigated the localization of FLT3, a subclass III receptor tyrosine kinase frequently mutated in leukemia. By immunofluorescence staining and confocal laser scanning microscopy we found that in retrovirally transduced COS7 cells, wild type FLT3 receptor protein is localized primarily at the cell surface. In contrast, a mutant FLT3 receptor protein with an internal tandem duplication (ITD) accumulates in a perinuclear region and is not detectable at the plasma membrane. Surprisingly, and in contrast to previously published data, intracellular FLT3-ITD accumulation could neither be detected in the endoplasmic reticulum (ER) nor in the Golgi apparatus. Furthermore, transient overexpression per se leads to accumulation of wild type FLT3 receptor protein in the ER in addition to surface localization, probably due to inefficient intracellular transport by the overloaded sorting machinery of the secretory pathway. Based on our data and the immature glycosylation pattern of FLT3-ITD, we speculate that the mutant protein resides most probably in an unidentified compartment of the secretory pathway between the ER and the Golgi apparatus.

Role of phosphorylation of ser10 of p27Kip1 in its subcellular localization in HepG2 cell lines

AIM: To investigate the influence of over-expression of exogenous p27^kip1 gene on cell cycle and proliferation in HepG₂ cell line, and to elucicate the role of phosphorylation of ser¹⁰ of p27^kip1 protein in its subcellular localization.

METHODS: Both plasmids containing the wild type and S10A p27^kip1 were transfected into HepG₂ cell lines with Lipofectamine separately. The exogenous p27^kip1 protein expression and subcellular localization was monitored with immunoflurescence under laser confocal microscope. Its biological effects on cell cycle and proliferation were determined by FACS and growth curves.

RESULTS: Over-expression of p27^kip1 protein was observed in transfected cells. As a result, the proliferation of HepG₂ cells was greatly inhibited and cell cycle was arrested in G₁ phase after exogenous p27^kip1 expression. Both the wild type and S10A p27^kip1 protein were distributed in the nucleus when synchronized at G₀ phase by serum deprivation for 96 hours. The wild type p27^kip1 protein was translocated from nucleus to cytoplasm when the cell was restimulated by exposure to 20% serum for 8 h, whereas the S10A p27^kip1 still presented in the nucleus.

CONCLUSION: The overexpression of p27^kip1 can inhibit the proliferation of HepG₂, and phosphorylation of p27^kip1 on serine¹⁰is required for its nuclear export.

Papillary carcinoma of the thyroid: methylation is not involved in the regulation of MET expression

Hypomethylation has been reported to be responsible for the activation of several oncogenes. The possibility that hypomethylation is involved in the regulation of MET transcription was investigated through the analysis of the methylation status of one CpG island containing 43 CpGs in six cases of papillary carcinoma, in the corresponding normal thyroid tissue, and in two cases of hyperplastic goitre. Evidence of methylation was not found in any of the analysed CpG.

Correlation of AgNORs, DNA contents and PCNA expression with liver cirrhosis, hyperplastic nodules and hepatocellular carcinoma

AIM: To study the relationship between liver cirrhosis (LC), liver hyperplastic nodules (LHN) and hepatocellular carcinoma (HCC).

METHODS: Silver colloid, image analysis and immunohistochemical technique were used to examine AgNORs counts, DNA contents and the expression of proliferating cell nuclear antigen (PCNA) in LC, LHN and HCC.

RESULTS: In LHN, the AgNORs counts, DNA contents and the expression of PCNA were significantly higher than those in the normal liver and LC (P < 0.01, P < 0.05, P < 0.05, respectively); the AgNORs counts approached those in HCC grade I (P > 0.05), and the DNA contents approached those in HCC (P > 0.05). There was no significant difference of AgNORs counts, DNA contents and the expression of PCNA between LC and the normal liver tissues.

CONCLUSION: LHN and LC are two different cell population with various characteristics; LHN is actively proliferative lesions and should be considered as a preneoplastic lesion of HCC, while LC represents mature liver cells and does not contribute directly to the hepatocarcinogenesis.

N/A

N/A

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.

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.

Influence of methionine/valine-depleted enteral nutrition on nucleic acid and protein metabolism in tumor-bearing rats

AIM: To investigate the effects of methionine/valine-depleted enteral nutrition (EN) on RNA, DNA and protein metabolism in tumor-bearing (TB) rats.

METHODS: Sprague-Dawlley (SD) rats underwent jejunostomy for nutritional support. A suspension of Walker-256 carcinosarcoma cells was subcutaneously inoculated. 48 TB rats were randomly divided in 4 groups: A, B, C and D. The TB rats had respectively received jejunal feedings supplemented with balanced amino acids, methionine-depleted, balanced amino acids and valine-depleted for 6 d before injection of 740 KBq ³H- methionine/valine via jejunum. The ³H incorporation rate of the radioactivity into RNA, DNA and proteins in tumor tissues at 0.5, 1, 2, 4 h postinjection of tracers was assessed with liquid scintillation counter.

RESULTS: Incorporation of ³H into proteins in groups B and D was (0.500 ± 0.020)% to (3.670 ± 0.110)% and (0.708 ± 0.019)% to (3.813 ± 0.076)% respectively, lower than in groups A [(0.659 ± 0.055)% to (4.492 ± 0.108)%] and C [(0.805 ± 0.098)% to (4.180 ± 0.018)%]. Incorporation of ³H into RNA, DNA in group B was (0.237 ± 0.075)% and (0.231 ± 0.052)% respectively, lower than in group A (P < 0.01). There was no significant difference in uptake of ³H by RNA and DNA between group C and D (P > 0.05).

CONCLUSION: Protein synthesis was inhibited by methionine/valine starvation in TB rats and nucleic acid synthesis was reduced after methionine depletion, thus resulting in suppression of tumor growth.

N/A

N/A

Expression of p53 and C-myc genes and its clinical relevance in the hepatocellular carcinomatous and pericarcinomatous tissues

AIM

To investigate the possible roles of p53 and C-myc genes in the primary hepatocellular carcinogenesis and the relationship between the liver hyperplastic nodule (LHN) and hepatocellular carcinoma(HCC).

METHODS

The expression of p53 and C-myc genes was detected immunohistochemically in 73 and 60 cases of HCC and pericarcinomatous tissues, respectively.

RESULTS

The positive expression of p53 in HCC was significantly higher than that in pericarcinomatous tissues (P<0.05). In pericarcinomatous tissues, the p53 expression was observed only in LHN, but not in liver cirrhosis (LC) and normal liver tissues. The positive expression rate of C-myc in HCC or LHN was significantly higher than that in LC or normal liver tissues (P<0.05 and P<0.01), however, no significant difference was found between HCC and LHN (P>0.05). The positive expression rate of p53 and C-myc in HCC was correlated with the histological differentiation, that in the poorly differentiated was significantly higher than that in well differentiated samples (P<0.05).

CONCLUSION

The overexpression of p53 and C-myc genes might play a role in the carcinogenesis of HCC; And LHN seems a preneoplastic lesion related to hepatocarcinogenesis; No evidence supports that LC contribute directly to the hepatocarcinogenesis.

The prognostic molecular markers in hepatocellular carcinoma

The prognosis of hepatocellular carcinoma (HCC) still remains dismal, although many advances in its clinical study have been made. It is important for tumor control to identify the factors that predispose patients to death. With new discoveries in cancer biology, the pathological and biological prognostic factors of HCC have been studied quite extensively. Analyzing molecular markers (biomarkers) with prognostic significance is a complementary method. A large number of molecular factors have been shown to associate with the invasiveness of HCC, and have potential prognostic significance. One important aspect is the analysis of molecular markers for the cellular malignancy phenotype. These include alterations in DNA ploidy, cellular proliferation markers (PCNA, Ki-67, Mcm2, MIB1, MIA, and CSE1L/CAS protein), nuclear morphology, the p53 gene and its related molecule MD M2, other cell cycle regulators (cyclin A, cyclin D, cyclin E, cdc2, p27, p73), oncogenes and their receptors (such as ras, c-myc, c-fms, HGF, c-met, and erb-B receptor family members), apoptosis related factors (Fas and FasL), as well as telomerase activity. Another important aspect is the analysis of molecular markers involved in the process of cancer invasion and metastasis. Adhesion molecules (E-cadherin, catenins, serum intercellular adhesion molecule-1, CD44 variants), proteinases involved in the degradation of extracellular matrix (MMP-2, MMP-9, uPA, uPAR, PAI), as well as other molecules have been regarded as biomarkers for the malignant phenotype of HCC, and are related to prognosis and therapeutic outcomes. Tumor angiogenesis is critical to both the growth and metastasis of cancers including HCC, and has drawn much attention in recent years. Many angiogenesis-related markers, such as vascular endothelial growth factor (VEGF), basic fibroblast growth factor (bFGF), platelet-derived endothelial cell growth factor (PD-ECGF), thrombospondin (TSP), angiogenin, pleiotrophin, and endostatin (ES) levels, as well as intratumor microvessel density (MVD) have been evaluated and found to be of prognostic significance. Body fluid (particularly blood and urinary) testing for biomarkers is easily accessible and useful in clinical patients. The prognostic significance of circulating DNA in plasma or serum, and its genetic alterations in HCC are other important trends. More attention should be paid to these two areas in future. As the progress of the human genome project advances, so does a clearer understanding of tumor biology, and more and more new prognostic markers with high sensitivity and specificity will be found and used in clinical assays. However, the combination of some items, i.e., the pathological features and some biomarkers mentioned above, seems to be more practical for now.

Expression of liver cancer associated gene HCCA3

AIM: To study and clone a novel liver cancer related gene, and to explore the molecular basis of liver cancer genesis.

METHODS: Using mRNA differential display polymerase chain reaction (DDPCR), we investigated the difference of mRNA in human hepatocellular carcinoma (HCC) and paired surrounding liver tissues, and got a gene probe. By screening a human placenta cDNA library and genomic homologous extend, we obtained a full-length cDNA named HCCA3. We analyzed the expression of this novel gene in 42 pairs of HCC and the surrounding liver tissues, and distribution in human normal tissues by means of Northern blot assay.

RESULTS: A full-length cDNA of liver cancer associated gene HCCA3 has been submitted to the GeneBank nucleotide sequence databases (Accession No. AF276707). The positive expression rate of this gene was 78.6% (33/42) in HCC tissues, and the clinical pathological data showed that the HCCA3 was closely associated with the invasion of tumor capsule (P = 0.023) and adjacant small metastasis satellite nodules lesions (P = 0.041). The HCCA3 was widely distributed in the human normal tissues, which was intensively expressed in lungs, brain and colon tissues, while lowly expressed in the liver tissues.

CONCLUSION: A novel full-length cDNA was cloned and differentiated, which was highly expressed in liver cancer tissues. The high expression was closely related to the tumor invasiveness and metastasis, that may be the late heredited change in HCC genesis.

Distribution of nitric oxide synthase in stomach myenteric plexus of rats

AIM: To study the distribution of nitric oxide synthase (NOS) in rat stomach myenteric plexus.

METHODS: The distribution of NOS in gastric wall was studied in quantity and location by the NADPH-diaphorase (NDP) histochemical staining method and whole mount preparation technique.

RESULTS: NOS was distributed in whole stomach wall, most of them were located in myenteric plexus, and distributed in submucosal plexus. The shape of NOS positive neurons was basically similar, most of them being round and oval in shape. But their density, size and staining intensity varied greatly in the different parts of stomach. The density was 62 ± 38 cells/mm² (antrum), 43 ± 32 cells/mm² (body), and 32 ± 28 cells/mm² (fundus), respectively. The size and staining intensity of NOS positive neurons in the fundus were basically the same, the neurons being large and dark stained, while they were obviously different in antrum. In the body of the stomach, the NOS positive neurons were in an intermediate state from fundus to antrum. There were some beadlike structures which were strung together by NOS positive varicosities in nerve fibers, some were closely adherent to the outer walls of blood vessels.

CONCLUSION: Nitric oxide might be involved in the modulation of motility, secretion and blood circulation of the stomach, and the significant difference of NOS positive neurons in different parts of stomach myenteric plexus may be related to the physiologic function of stomach.

Clinical application of serial operations with preserving spleen

AIM: To evaluate the clinical application of serial operations with preservation of spleen.

METHODS: Serial operations with preserving spleen were performed on 211 cases in our hospital from 1980 to 2000. The patient’s age ranged from 13 to 56 years, averaging 38 years. Diseases included splenic injury in 171 cases, portal hypertension in 9 cases, splenic cyst in 10 cases, and the lesion of pancreatic body and tail in 21 cases.

RESULTS: All the cases were cured, and 129 patients were followe dup from 3 mo to 3 years with the leukocyte phagocytosis test, detection of immunoglubin, CT, ^99mTc scanning and ultrasonography. The results were satisfactory.

CONCLUSION: The operations with preserving spleen were safe, feasible, and worth of clinical application.