We investigated the expression of the growth-related nuclear proto-oncogenes, c-fos and c-myc, in early preneoplastic regions and tumor nodules of 3'-MeDAB induced rat hepatocarcinoma. To amplify the levels of these transcripts, we gave cycloheximide (100 mg/kg B.W. i.p.) to each group of rats. The elevated levels of the 2.2 kb c-fos and 2.4 kb c-myc transcripts appeared as early as the 2nd week after feeding on the 3'-MeDAB diet and lasted through the 4th; 6th weeks and tumor. Southern blot analysis indicated that gross amplification or rearrangements were not observed in DNA of the preneoplastic livers and hepatoma nodules. We also measured the rate of the incorporation of [3H] thymidine into hepatic DNA in order to monitor the rate of cell proliferation occurring at the early preneoplastic periods. We have found that the rate of [3H] thymidine incorporation corresponds to the elevated levels of c-fos and c-myc transcripts in the precancerous stages. This finding suggests that the elevated expressions of c-fos and c-myc may result from the continuous cell proliferative stimuli generated in the carcinogen altered cells, which is essential to the initiation and promotion of chemical hepatocarcinogenesis.
Animal ; Blotting, Southern ; DNA/biosynthesis ; Female ; *Gene Expression ; *Genes, fos ; *Genes, myc ; Liver Neoplasms, Experimental/chemically induced/*genetics ; Methyldimethylaminoazobenzene/*toxicity ; Precancerous Conditions/chemically induced/*genetics ; Rats ; Rats, Sprague-Dawley ; Support, Non-U.S. Gov't

OBJECTIVETo investigate the changes of miR-155 and its target genes in colitis-associated carcinogenesis.

METHODSColitis-associated colon cancer was induced by azoxymethane (AOM) and dextran sulfate sodium (DSS) in C57BL/6 mice. Mice of three different stages during the development of colon cancer were obtained, named AD1, AD2 and AD3, respectively. A control group of mice without any treatment and a DSS only group representing chronic inflammation without cancer were set up as well. Colon tissue was collected and expression of miR-155 in the colon tissues was measured by real-time fluorescent quantitative PCR. TargetScan and PicTar were used to predict potential target genes of miR-155, which were then preliminarily screened with our gene expression microarray database of AOM-DSS mouse model. Regular PCR was used to confirm the changes of the expression of these potential target genes in AOM-DSS mouse model.

RESULTSColitis-associated colon cancer was effectively induced by azoxymethane and dextran sulfate sodium in C57BL/6 mice. Histological examination revealed that the evolution process was sequentially from normal, mild dysplasia, moderate dysplasia, and severe dysplasia to adenocarcinoma in the AOM-DSS mouse model. The level of miR-155 was gradually elevated with the formation of colitis-associated colon cancer. There was no significant difference between the levels of miR-155 expression in the DSS group (0.005 6 ± 0.003 7) and control group (0.012 0 ± 0.005 1) (P > 0.05), but the level of miR-155 in the AD3 group (0.054 4 ± 0.027 0) was significantly higher than that of the DSS group (0.005 6 ± 0.003 7)(P < 0.01). No significant change of miR-155 expression was found in the DSS only group. The relative expression levels of miR-155 in the control group, DSS only group and AD3 group were 0.012 0 ± 0.005 1, 0.005 6 ± 0.003 7, 0.054 4 ± 0.027 0, respectively. Data analysis with the gene expression microarray showed that Tle4, Kcna1, Itk, Bcorl1, Cacna1c, Rspo2 and Foxo3 were potential target genes of miR-155 in the AOM-DSS mouse model. Changes of Kcna1 and Cacna1c in the AOM-DSS mouse model were validated to be consistent with the changes obtained with the gene expression microarray.

CONCLUSIONThe up-regulation of miR-155 is related to colitis-associated carcinogenesis, but is irrelevant to chronic inflammation in the mouse model.

Adenocarcinoma ; chemically induced ; genetics ; metabolism ; Animals ; Azoxymethane ; toxicity ; Carcinogens ; toxicity ; Cocarcinogenesis ; Colitis ; chemically induced ; genetics ; metabolism ; Colon ; metabolism ; Colonic Neoplasms ; chemically induced ; genetics ; metabolism ; Dextran Sulfate ; toxicity ; Gene Expression Profiling ; Male ; Mice ; Mice, Inbred C57BL ; MicroRNAs ; metabolism ; Precancerous Conditions ; chemically induced ; genetics ; metabolism ; Up-Regulation

OBJECTIVETo investigate the enhancive effect of N,N'-dinitrosopiperazine (DNP) on induced carcinogenesis in nasal and/or nasopharyngeal epithelia among TgN(p53mt-LMP1)/HT transgenic mice to examine the underlying mechanism for the development of nasopharyngeal carcinoma (NPC).

METHODSTgN(p53mt-LMP1)/HT transgenic mice and the same strain of C(57)BL/6J wild-type mice both at the age of 5 months were randomly divided into 2 groups in parallel, respectively, i.e., TgN(p53mt-LMP1)/HT cancerous lesion-inducing group (TI), TgN(p53mt-LMP1)/HT control group (TC), C57BL/6J cancerous lesion-inducing group (CI), and C57BL/6J control group (CC). TI and CI mice were treated only with DNP for 16 weeks, twice each week, while TC and CC mice were given the same volume of saline as controls. At the end of treatment, animals were sacrificed to collect epithelial tissue samples from nasal cavity and nasopharynx for pathohistological evaluation by haematoxylin and eosin (HE) staining and for determination on the expression of TRAF2, c-Jun, and p16 by immunohistochemistry.

RESULTSAtypical hyperplasia was more significant in the samples of TI than in those of TC, CI, and CC, with the rates of lesions being 90%, 10%, 0, and 0 (P<0.01) respectively, though DNP was used alone in a much shortened inducing period at less dosage and without the use of carcinogenic promoter 12-O-tetradecanoylphorbol-13-acetate as usual. The expressions of tumor necrosis factor (TNF) receptor-associated factor 2 (TRAF2) and c-Jun in these samples were significantly up-regulated in TI (P<0.01), while the expression of p16 was significantly lower in TI than in the other groups (P<0.01).

CONCLUSIONTgN(p53mt-LMP1)/HT mice hold inherited constitutional defect in immune surveillance function, which can be aggravated by environmental carcinogens, such as DNP used even though in a much less strength. The enhanced carcinogenesis-inducing effect of DNP on TgN(p53mt-LMP1)/HT mice should be closely associated with abnormal signaling of activator protein-1 (AP-1) pathway, especially up-regulated expressions of TRAF2 and c-Jun, and down-regulated expression of p16.

Animals ; Epithelial Cells ; drug effects ; metabolism ; pathology ; JNK Mitogen-Activated Protein Kinases ; metabolism ; Mice ; Mice, Transgenic ; Mutation ; genetics ; Nasopharyngeal Neoplasms ; chemically induced ; genetics ; metabolism ; pathology ; Nitrosamines ; pharmacology ; Nose Neoplasms ; chemically induced ; genetics ; metabolism ; pathology ; Precancerous Conditions ; chemically induced ; genetics ; pathology ; TNF Receptor-Associated Factor 2 ; metabolism ; Tumor Suppressor Protein p53 ; genetics ; metabolism ; Viral Matrix Proteins ; genetics ; metabolism

OBJECTIVETo examine and analyze the global gene expression at the different stages of golden hamster cheek pouch mucosa carcinomatous change induced by 9,10-dimethylene-1,2 benzanthracene (DMBA).

METHODSThe model of golden hamster cheek pouch squamous cell carcinoma was induced by DMBA. The RNA of normal mucosa, precancerous lesions and squamous cell carcinoma of fresh tissue of golden hamsters was extracted and purified and the cRNA labeled by fluorescent Cy3 synthesized, which respectively hybridized with the agilent rat cDNA microarray containing 41 000 genes-expressed sequence tags, scanning with Agilent G2565AA fluorescence scanner. The Ratio>or=2 and Ratio

RESULTSA total of 5255 differentially expressed genes were detected during the process from normal mucosa to the squamous cell carcinoma, of which 2896 was up-regulated and 2359 down-regulated. There were 22 genes that showed continues abnormal expression through the three different stages of carcinomatous change, including 3 up-regulated, 19 down-regulated. The RT-PCR results of Eaf-2 and Ecg-2 were consistent with the gene chip.

CONCLUSIONSThe development of oral mucosal squamous cell carcinoma involved a number of abnormal genes. The genes showing continues abnormal expression at different stages of carcinomatous change may be the important pathogenetic ones.

9,10-Dimethyl-1,2-benzanthracene ; Animals ; Carcinogens ; Carcinoma, Squamous Cell ; chemically induced ; genetics ; pathology ; Cheek ; Cricetinae ; Female ; Gene Expression Profiling ; Gene Expression Regulation, Enzymologic ; Male ; Mesocricetus ; Mouth Mucosa ; metabolism ; Mouth Neoplasms ; chemically induced ; genetics ; pathology ; Oligonucleotide Array Sequence Analysis ; Precancerous Conditions ; chemically induced ; genetics ; pathology ; RNA, Complementary ; genetics ; Random Allocation ; Reverse Transcriptase Polymerase Chain Reaction

OBJECTIVETo investigate the expression and circadian rhythm variation of biological clock gene Per1 and cell cycle genes p53, CyclinD1, cyclin-dependent kinases (CDK1), CyclinB1 in different stages of carcinogenesis in buccal mucosa and its relationship with the development of buccal mucosa carcinoma.

METHODSNinety golden hamsters were housed under 12 hours light-12 hours dark cycles, and the model of buccal squamous cell carcinoma was established by using the dimethylbenzanthracene (DMBA) to smear the golden hamster buccal mucosa. Before the DMBA was used and after DMBA was used 6 weeks and 14 weeks respectively, the golden hamsters were sacrificed at 6 different time points (5 rats per time point) within 24 hour, including 4, 8, 12, 16, 20 and 24 hour after lights onset (HALO), and the normal buccal mucosa, precancerous lesions and cancer tissue were obtained, respectively. HE stained sections were prepared to observe the canceration of each tissue. Real time RT-PCR was used to detect the mRNA expression of Per1, p53, CyclinD1, CDK1 and CyclinB1, and a cosine analysis method was applied to determine the circadian rhythm variation of Per1, p53, CyclinD1, CDK1 and CyclinB1 mRNA expression, which were characterized by median, amplitude and acrophase.

RESULTSThe expression of Per1, p53, CDK1 and CyclinD1 mRNA in 6 different time points within 24 hours in the tissues of three different stages of carcinogenesis had circadian rhythm, respectively. However, the CyclinB1 mRNA was expressed with circadian rhythm just in normal and cancer tissue (P < 0.05), while in precancerous lesions the circadian rhythm was in disorder (P > 0.05). As the development of carcinoma, the median of Per1 and p53 mRNA expression were significantly decreased (P < 0.05), yet the median of CDK1, CyclinB1 and CyclinD1 mRNA expression were significantly increased (P < 0.05). The amplitude of Per1, p53 and CyclinD1 mRNA expression was significantly decreased as the development of carcinoma (P < 0.05), however the amplitude of CDK1 mRNA expression was significantly increased (P < 0.05). In addition, there was no significant difference in the amplitude of CyclinB1 mRNA expression. The time that the peak expression value of Per1 and CDK1 mRNA appeared (Acrophase) in precancerous lesions was remarkably earlier than that in normal tissues, but the acrophase of p53 and CyclinD1 mRNA expression was remarkably delayed. Moreover, the acrophase of CDK1 and CyclinB1 mRNA expression in cancer tissues was obviously earlier than that in normal tissues, yet there was no significant variation in acrophase of Per1, p53, CyclinD1 mRNA expression between normal tissues and cancer tissues.

CONCLUSIONSThe circadian rhythm of clock gene Per1 and cell cycle genes p53, CyclinD1, CDK1, CyclinB1 expression remarkably varied with the occurrence and development of carcinoma. Further research into the interaction between circadian and cell cycle of two cycle activity and relationship with the carcinogenesis may providenew ideas and methods of individual treatment and the mechanism of carcinogenesis.

9,10-Dimethyl-1,2-benzanthracene ; Animals ; CDC2 Protein Kinase ; genetics ; Carcinogenesis ; Carcinogens ; Carcinoma, Squamous Cell ; chemically induced ; genetics ; pathology ; Cell Cycle ; Circadian Rhythm ; genetics ; Cricetinae ; Cyclin B1 ; genetics ; Disease Models, Animal ; Gene Expression Regulation, Neoplastic ; Genes, bcl-1 ; Genes, p53 ; Mesocricetus ; Mouth Mucosa ; Mouth Neoplasms ; chemically induced ; genetics ; pathology ; Period Circadian Proteins ; genetics ; Precancerous Conditions ; genetics ; RNA, Messenger ; metabolism ; Rats ; Real-Time Polymerase Chain Reaction ; Time Factors