The immortalization and transformation of cultured human cells has far-reaching implications for both cell and cancer biology. Human cell transformation studies will increase our understanding of the mechanisms underlying carcinogenesis and differentiation. The neoplastic process can now be studied in a model human cell culture system. The accompanying biochemical and genetic changes, once identified, will help define the relationship between malignancy and differentiation. The present studies indeed demonstrate that the neoplastic process can now be studied in a human cell model system. Primary human cells treated with various carcinogens became immortalized in culture but were not tumorigenic. Additional exposure to either retroviruses, chemical carcinogenes or X-ray irradiation to these cells induced morphological alterations associated with the acquisition of neoplastic properties. These findings demonstrate the malignant transformation of human primary cells in culture by the combined action of either a DNA transforming virus and a retrovirus or a DNA virus and a chemical or X-ray irradiation, and support an multistep process for neoplastic conversion. It has been known that normal human cells in culture are remarkably resistant to experimentally induced tumorigenicity. However, as shown above, normal human cells could now be transformed into tumorigenic cells.
*Cell Transformation, Neoplastic/genetics ; Cells, Cultured ; DNA, Viral ; Fibroblasts/pathology ; Human ; Keratinocytes/cytology/pathology ; Osteosarcoma/genetics/pathology

BACKGROUNDTo construct human papillomavirus type 18 (HPV18 E6E7) adeno-associated virus (AAV) for studying the role of HPV E6E7 in the development of human cancer.

METHODSHPV18 E6E7 genes were inserted into adeno-associated virus expression vector and then infected 293 cell line. The expression of HPV18 E6E7 genes were confirmed by using RT-PCR/Southern blot assay.

RESULTSThere was HPV18 E6E7 genes in the malignantly transformed cell line. The 293TL cells compared with the parent cells transformed cells grew more rapidly, lost their contact inhibition and formed more and large colonies in soft agar.

CONCLUSIONSHPV18 E6E7 AAV was successfully constructed and could induce malignant transformation. HPV18 E6E7 AAV can be use for studying the immortalization and malignant transformation of human normal epithelial cells.

Cell Line ; Cell Transformation, Neoplastic ; Cell Transformation, Viral ; DNA, Viral ; analysis ; DNA-Binding Proteins ; Dependovirus ; genetics ; Epithelial Cells ; cytology ; virology ; Fetus ; Humans ; Kidney ; cytology ; Oncogene Proteins, Viral ; genetics ; Papillomaviridae ; genetics ; Polymerase Chain Reaction

bcl-2 and c-myc protein expression were studied in 44 epidermal (8 seborrheic keratoses, 21 squamous cell carcinomas, and 15 basal cell carcinomas), and 26 melanocytic tumors(8 nevi, and malignant melanomas) by immunohistochemistry using the specific anti-bcl-2 and anti-c-myc monoclonal antibodies. 14 out of 15 basal cell carcinomas(BCC) (93.3%) showed expression of bcl-2 protein, 12 of which (85.7%) showed coexpression of c-myc protein. In the melanocytic tumors, 7 out of 8 nevi showed bcl-2 expression (87.5%). Five of these 7 cases (62.5%) also showed c-myc protein expression. Eight of 18 malignant melanomas(MM) (44.4%) showed expression of bcl-2 protein and 7 of these 8 cases (38.9%) also showed c-myc protein expression. All seborrheic keratoses and squamous cell carcinoma(SCC) were negative for bcl-2 proteins. 12 of 15 SCCs(80%) were positive for c-myc protein. In conclusion, bcl-2 and c-myc proteins were coexpressed in BCCs, nevi, and MMs. Coexpression of bcl-2 and c-myc proteins in these tumors was statistically significant(p<0.01), while no considerable differences of bcl-2 and c-myc expression were found between nevi and MMs. These results suggests that bcl-2 may cooperate with c-myc to promote tumorigenesis of BCCs, nevi, and MMs(p<0.01).
Cell Transformation, Neoplastic

BACKGROUND AND OBJECTIVES: Although the role of c-myb in head and neck tumor has not been studied, aberrant expression of c-myb in various cancer has been demonstrated recently, suggesting that c-myb may play a role in tumorigenesis. Consequently, disrupting c-myb function might prove a possible stratergy for controlling cancer cell growth. The purpose of this study is to investigate the possibility of clinical application of adenovirus-mediated dominant negative c-myb (DN-myb) gene therapy in head and neck cancer. MATERIALS AND METHOD: All tissues were obtained from patients undergoing therapeutic operation for head and neck tumors and were assayed the expression of c-myb and bcl-2 in tumor and normal tissue by RT-PCR. We have generated a replication-deficient recombinant adenovirus encoding the dominant negative c-myb (Ad/DN-myb) or control adenovirus encoding no transgene (Ad/GFP) and infected adenovirus to SNU-1076, head and neck tumor cell line. We examined cell proliferation by 3H-thymidine assay, apoptosis by DNA fragmentation, bcl-2 expression and Akt/PKB phosphorylation by Western immunoblot, and IGF-II, VEGF mRNA expression by RT-PCR. RESULTS: c-myb expression of head and neck tumor tissues was significantly higher than that of normal tissue, indicating that these genes may play an important role in carcinogenesis of head and neck tumor. Ad/DN-myb infected SNU-1076 cells decreased cell proliferation, IGF-1I and VEGF expression, and remarkably increased their apoptosis through the down-regulation of bcl-2 expression and the inhibition of Akt/PKB pathway activation. CONCLUSION: Results obtains from these study suggest that DN-myb induced apoptosis of head and neck tumor cells and the adenovirusmediated DN-myb gene therapy may be a potential molecular therapy for the treatment of head and neck tumor.
Cell Transformation, Neoplastic

OBJECTIVETo study the effect of hepatitis C virus core protein (HCV-C) on human normal biliary epithelial cells (BEC) transformation and tumor development.

METHODSBEC cells were transfected with plasmid pcDNA HCV-C (expressing HCV-C) by lipofectamine and selected in G418. The expression of HCV-C gene and protein was determined by PCR and immunohistochemical staining, respectively. Biological effect of transfected cells was observed through cell proliferation assay, anchor independent growth, and tumor development in nude mice. The expression of HCV-C protein in the induced tumor was evaluated by immunohistochemistry.

RESULTSHCV-C was strongly expressed in BEC cells transfected with plasmid pcDNA HCV-C and the positive signal was located in cytoplasm. The HCV-C expression protein in the induced cytoplasm. Cell proliferation assay showed that the population doubling time in the pcDNA HCV-C transfected cells was much shorter than that in the pcDNA3 and non-transfected cells (14 h, 28 h, 30 h respectively). The cloning efficiencies of transfected cells with pcDNA HCV-C, pcDNA3 and non-transfected cells were 36%, 2.5% and 1.5%, respectively (P < 0.01). Tumor developed in nude mice inoculated with pcDNA HCV-C transfected cells after the inoculation. HE staining showed bile duct carcinoma character and immunohistochemistry confirmed HCV-C expression in the tumor tissue. The positive control group also showed tumor development, while no tumor mass obtained in the nude mice inoculated with pcDNA3 and non-transfected cells even 36 days after the injection.

CONCLUSIONHCV-C protein showed human normal biliary epithelial cells transformation and tumorigenic features.

Animals ; Bile Duct Neoplasms ; etiology ; Bile Ducts ; cytology ; Cell Transformation, Neoplastic ; Cell Transformation, Viral ; Cells, Cultured ; Epithelial Cells ; pathology ; Female ; Hepacivirus ; Humans ; Mice ; Mice, Nude ; Plasmids ; Transfection ; Viral Core Proteins ; physiology

OBJECTIVETo study the effect of hepatitis C virus nonstructural protein 3 N-terminal protein (HCV NS3-5') on hepatocyte transformation and tumor development.

METHODSQSG7701 cells were transfected with plasmid pRcHCNS3-5' (expressing HCV NS3 N-terminal protein) by lipofectamine and selected in G418. The expression of HCV NS3 gene and protein was determined by PCR and immunohistochemistry respectively. Biological effect of transfected cells was observed through cell proliferation assay, anchor independent growth, and tumor development in nude mice. The expression of HCV NS3 and c-myc protein in the induced tumor was evaluated by immunohistochemistry.

RESULTSHCV NS3 was strongly expressed in QSG7701 cells transfected with plasmid pRcHCNS3-5' and the positive signal was located in cytoplasm. The HCV NS3 expression and c-myc protein in the induced cytoplasm. Cell proliferation assay showed that the population doubling time in the pRcHCNS3-5' transfected cells was much shorter than that in the pRcCMV and non-transfected cells (24 h, 26 h, 28 h respectively). The cloning efficiencies of transfected cells with pRcHCNS3-5', pRcCMV and non-transfected cells were 33.0%, 1.5%, 1.1% respectively (P < 0.01). Tumor developed in nude mice inoculated with pRcHCNS3-5'transfected cells 15 days after the inoculation. HE staining showed hepatocarcinoma character and immunohistochemistry confirmed HCV NS3 and c-myc expression in the tumor tissue. The positive control group also showed tumor development, while no tumor mass obtained in the nude mice inoculated with pRcCMV and non-transfected cells even 40 days after the injection.

CONCLUSIONHCV NS3 N-terminal protein showed cell transformation and tumorigenic features.

Animals ; Cell Division ; Cell Transformation, Neoplastic ; Female ; Hepatocytes ; pathology ; Humans ; Liver Neoplasms, Experimental ; etiology ; Mice ; Mice, Nude ; Mitogen-Activated Protein Kinases ; metabolism ; Phosphorylation ; Transfection ; Viral Nonstructural Proteins ; toxicity

OBJECTIVE: To investigate the proteome of hepatocyte transformation by hepatitis C virus (HCV) nonstructural protein 3 (NS3). METHODS: Human hepatocyte line QSG7701 stably expressing HCV NS3 C-terminal deleted protein was constructed, which was named pRcHCNS3/QSG. Two-dimensional electrophoresis (2-DE) was used to separate the total protein of pRcHCNS3/QSG and pRcCMV transfected cells (pRcCMV/QSG) respectively. Differentially expressed protein spots were identified by mass spectrometry. Western blot confirmed the differentially expressed proteins. RESULTS: 2-DE profiles with high resolution and reproducibility were obtained. The average spots of pRcHCNS3/QSG and pRcCMV/QSG were (1183+/-77) and (1095+/-82) respectively, and (920+/-60) spots were matched. Twenty-one differentially expressed protein spots were chosen randomly and 15 were identified by mass spectrometry. Some proteins such as Ras, P38 and HD53 which were involved in signal transduction were increased in pRcHCNS3/QSG cells. Western blot also showed strong expression of phosphorylated P44/42 and P38 in pRcHCNS3/QSG cells. Other differentially expressed proteins were related to cell cycle regulation, immunoreaction, tumor invasion and metastasis, and liver metabolizability. CONCLUSION HCV NS3 might be involved in cell malignant transformation through affecting protein expression and signal transduction such as MAPK cascade. Further study on the signal transductions and their relationship would not only be helpful to explore the mechanism of HCV related HCC, but also provide a new idea for the molecular treatment of HCC.
Cell Line ; Cell Transformation, Neoplastic ; Electrophoresis, Gel, Two-Dimensional ; methods ; Hepatocytes ; metabolism ; pathology ; Humans ; Mass Spectrometry ; methods ; Proteome ; analysis ; Proteomics ; methods ; Transfection ; Viral Nonstructural Proteins ; biosynthesis ; genetics

Hepatitis C virus (HCV) is an RNA virus that is unable to integrate into the host genome. However, its proteins interact with various host proteins and induce host responses. The oncogenic process of HCV infection is slow and insidious and probably requires multiple steps of genetic and epigenetic alterations, the activation of cellular oncogenes, the inactivation of tumor suppressor genes, and dysregulation of multiple signal transduction pathways. Stellate cells may transdifferentiate into progenitor cells and possibly be linked to the development of hepatocellular carcinoma (HCC). Viral proteins also have been implicated in several cellular signal transduction pathways that affect cell survival, proliferation, migration and transformation. Current advances in gene expression profile and selective messenger RNA analysis have improved approach to the pathogenesis of HCC. The heterogeneity of genetic events observed in HCV-related HCCs has suggested that complex mechanisms underlie malignant transformation induced by HCV infection. Considering the complexity and heterogeneity of HCCs of both etiological and genetic aspects, further molecular classification is required and an understanding of these molecular complexities may provide the opportunity for effective chemoprevention and personalized therapy for HCV-related HCC patients in the future. In this review, we summarize the current knowledge of the mechanisms of hepatocarcinogenesis induced by HCV infection.
Capsid Proteins/metabolism ; Carcinoma, Hepatocellular/genetics/*metabolism/pathology ; Cell Transformation, Neoplastic ; Genome, Viral ; Genome-Wide Association Study ; Hepacivirus/genetics/*metabolism ; Humans ; Liver Neoplasms/genetics/*metabolism/pathology ; MicroRNAs/metabolism

N-acetyl-seryl-aspartyl-lysyl-proline (Ac-SDKP) is an endogenous short peptide produced through the continuous hydrolysis of Thymosin β4 by meprin-α and prolyl oligopeptidase. It has the functions of immune regulation, promoting angiogenesis, tumorigenesis and anti-fibrosis in organs. In this paper, according to some our research results and related literatures in recent years, a review of Ac-SDKP research progress was written.
Humans ; Oligopeptides ; Cell Transformation, Neoplastic

BACKGROUNDStudy on the promotive effects of N-nitrosopiperidine on carcinogenesis process was performed, based on the immortalization of human fetal esophageal epithelium induced by human papillomavirus (HPV) 18E6E7 genes.

METHODSThe immortalized esophageal epithelium SHEE was induced by HPV18E6E7. The cells at 17th passages were cultured in 50 ml flasks. The N-nitrosopiperidine (NPIP) 0, 2, 4, 8 mmol/L added to the cultured medium of SHEE cells for 3 weeks. The morphology, proliferation and apoptosis of the cells were studied by phase contrast microscopy and flow cytometry. Modal number of chromosomes was analyzed by standard method. Tumorigenicity of the cells was assessed by soft agar colony formation and by transplantation of cells into nude mice. Expression of HPV was detected by Western blot.

RESULTSWhen cells were exposed to high concentration (8 mmol/L) of NPIP, cell death was increased, leaving a few live cells. In normal cultural medium instead of NPIP proliferative status of the cells restored after 4 weeks and the cells progressed to the proliferation stage with continuous replication and atypical hyperplasia. At the end of the 8th week, the cells appeared with large colonies in soft-agar and tumor formation in transplanted nude mice. When the cells were cultured in 2, 4 mmol/L NPIP the doubling passage was delayed and without tumor formation in transplanted nude mice. Modal number of chromosomes was 61-65, in 8 mmol/L NPIP group and control group, 56-61. Expression of HPV18 appeared in experimental and control groups.

CONCLUSIONNPIP promotes malignant change of the immortalized esophageal epithelial cells induced by HPV18E6E7. HPV18E6E7 synergy with NPIP will accelerate malignant transformation in esophageal epithelium.

Animals ; Blotting, Western ; Cell Cycle ; drug effects ; Cell Line ; Cell Proliferation ; drug effects ; Cell Transformation, Neoplastic ; drug effects ; Cell Transformation, Viral ; drug effects ; DNA-Binding Proteins ; metabolism ; Epithelial Cells ; cytology ; drug effects ; virology ; Esophagus ; cytology ; Flow Cytometry ; Human papillomavirus 18 ; physiology ; Humans ; Mice ; Mice, Inbred BALB C ; Mice, Nude ; Neoplasms, Experimental ; metabolism ; pathology ; Nitrosamines ; toxicity ; Oncogene Proteins, Viral ; metabolism