Biomedical subjects

G Manenti

Publications and source records attributed to G Manenti.

At least 73 records · Page 4Linked to original sources

PubMed1993

A major susceptibility locus to murine lung carcinogenesis maps on chromosome 6.

Lung tumours represent a major cause of death in humans, and although smoking represents the main pathogenetic factor, inheritance also plays a part. However, the identification of possible predisposing genetic factors is difficult, because of their low penetrance. We took advantage of murine strains that are genetically susceptible or resistant to lung tumour development, to map murine genes associated with susceptibility to lung carcinogenesis. An F2 population of urethan-treated A/J x C3H/He mice was scored with 83 genetic markers. A chromosome 6 distal region, spanning mice was scored with 83 genetic markers. A chromosome 6 distal region, spanning 35 centiMorgans, contained a major lung tumour susceptibility locus. No other chromosomal region was significantly associated with lung tumour development.

Animals↗

PubMed1992

Multiple molecular alterations in mouse lung tumors.

Twenty-five mouse lung tumors induced by a single urethan treatment in female A/J, BALB/c, and (A/J x C3H/He)F1 (AC3) mice were analyzed for the presence of mutations at codon 61 of the Ki-ras gene and for the expression of the surfactant protein A (SP-A), retinoblastoma (Rb), growth arrest-specific-3 (gas-3), p53, c-myc, and thymidylate synthase (TS) genes. Ki-ras codon 61 mutations were detected in 22 of 25 tumor samples without differences among strains. In comparison with normal lungs, all the tumors showed increased SP-A mRNA levels, indicating their derivation from alveolar type II pneumocytes or Clara cells. Rb and gas-3 transcripts were instead found in all tumors at about tenfold and about 20-fold reduced levels, respectively. No apparent structural alterations or loss of heterozygosity at the Rb locus was detected in any tumors. The p53 mRNA was observed without variation in quantity or size in lung tumors and normal tissue. A threefold to fivefold c-myc overexpression was observed, without amplification of the gene. TS expression was only slightly increased, indicating no great differences in cell proliferation between lung tumors and normal tissue. Our data suggest that the pathogenesis of urethan-induced lung tumors in mice involves specific and recurrent molecular alterations (Ki-ras mutations, decrease of Rb and gas-3 expression, and increase of c-myc expression) that could represent different steps in lung carcinogenesis.

Animals↗

PubMed1992

Rapid induction of apoptosis in rat liver by cycloheximide.

A single administration of the inhibitor of protein synthesis cycloheximide results in the occurrence of apoptosis in rat liver. The presence of intracellular apoptotic bodies was detected as early as 2 hours after treatment. No evidence of cell necrosis could be observed by histologic and biochemical analysis. Apoptosis was followed by an increased expression of testosterone-repressed prostate message-2 RNA, a gene whose activity has been associated to apoptotic cell death in involuting rat prostate. The finding of in vivo induction of apoptosis in nonproliferating cells by an inhibitor of protein synthesis, together with the rapidity and synchrony in the occurrence of cell death make this model potentially useful for the analysis of the kinetics of the apoptotic cycle and in exploring some of the mechanisms of regulation of genes possibly involved in this type of cell death.

Animals↗

PubMed1991

Quantitative analysis of genetic susceptibility to liver and lung carcinogenesis in mice.

One-week-old male and female mice of the A, BALB/c (C), and C3H/He (C3) strains and of the AC3 and CC3 F1 hybrids were treated with a single dose (300 mg/kg s.c.) of urethan and then kept without further treatment until 30 and 40 weeks (males) or 30 and 65 weeks (females). The degree of difference in susceptibility to hepatocarcinogenesis between the susceptible C3 and the resistant A and C mice, in the different age and sex groups, was 4-12-fold by the analysis of the number of nodules/cm3 (N/cm3), which represents an estimation of tumor frequency and was more than 400-fold as indicated by the percentage of liver volume occupied by nodules (V%), an estimation of tumor size. With regard to lung carcinogenesis, mice of the A strain proved 5-10- and 20-70-fold more susceptible than the C and the C3 mice, respectively, as indicated by the number of microscopically identified lung tumors/mouse (N), an estimation of tumor frequency. The lung tumor size, as estimated by the mean tumor volume (V), was similar in A and C mice but much higher in the A than in the C3 groups (13- approximately 1000-fold difference). The AC3 hybrid was highly susceptible to both liver and lung carcinogenesis. The CC3 hybrid was as susceptible to lung carcinogenesis as its C parent and had an intermediate susceptibility to hepatocarcinogenesis. Our results indicate that a major determinant in the genetic susceptibility to hepatocarcinogenesis, and perhaps to lung carcinogenesis too, is tumor growth, as evidenced by a much greater tumor size in genetically susceptible than resistant mice.

Age Factors↗

PubMed1991

Expression of the pp63 gene encoding the insulin receptor tyrosine kinase inhibitor in proliferating liver and in liver tumors.

After partial hepatectomy in rats, a approximately 4-fold decrease in pp63 mRNA level was detected at 24 h, but not at earlier time points. In mice, during liver cell proliferation induced by 1,4-bis[2-(3,5-dichloropyridyloxy)]benzene and phenobarbital, pp63 transcript levels had a decrease of 40-50%. However, pp63 mRNA was 5-6 fold higher in murine hepatocellular tumors than in normal adult mouse liver.

Animals↗

PubMed1991

Expression of housekeeping genes in Hodgkin's disease lymph nodes.

Housekeeping genes, particularly actin, tubulin, and the glycolytic enzyme glyceraldehyde-3-phosphate dehydrogenase (GAPDH), are widely used to estimate the amount and integrity of RNA in Northern blotting. In this work, the most reliable housekeeping gene for gene expression analysis of Hodgkin's disease (HD) lymph nodes was determined by comparing the conventional housekeeping genes, beta-actin, beta-tubulin, GAPDH, and the mouse gene LLRep3, that had been used previously in gene expression studies. It was found that the amounts of mRNA in these genes are very heterogeneous in HD lymph nodes. In contrast, their expression was relatively constant in tonsils undergoing a chronic inflammatory process. It is concluded that none of the housekeeping genes tested is suitable for the fine quantitative analysis of gene expression in HD lymph nodes.

Actins↗

PubMed1991

Incidence of mutations at codon 61 of the Ha-ras gene in liver tumors of mice genetically susceptible and resistant to hepatocarcinogenesis.

By selective oligonucleotide hybridization of polymerase chain reaction (PCR) amplified tumor DNAs we have analysed the incidence of mutations at codon 61 of the Ha-ras gene in 42 liver tumors spontaneously developed in Balb/c, C3Hf and B6C3 male mice, and in 79 liver tumors induced by the chemical carcinogens diethylnitrosamine (NDEA) and urethan in B6C3 and B6C male and female mice. The incidence of Ha-ras gene mutations in both spontaneously developed and urethan-induced liver tumors was 50%-63% in mice genetically susceptible to hepatocarcinogenesis (C3Hf, B6C3) and 7%-9% in mice genetically resistant (Balb/c, B6C). Urethan-induced tumors showed about the same incidence of ras mutations in male and in female B6C3 mice. NDEA-induced tumors showed a low incidence of Ha-ras mutations in both the hybrid mice (3/18 and 1/13 in B6C3 and B6C male mice, respectively). The most frequently found mutations were a C----A transversion at the 1st base of codon 61 in spontaneous tumors, and an A----T transversion at the 2nd base in urethan-induced tumors. Our results indicate that liver tumors induced by NDEA or urethan or spontaneously arisen have a different pattern of Ha-ras mutations at codon 61 and that these mutations constitute a rare molecular alteration in the pathogenesis of liver tumors in genetically resistant mice.

Animals↗

PubMed1990

Transgenic mice containing hepatitis B virus sequences are more susceptible to carcinogen-induced hepatocarcinogenesis.

Transgenic mice containing one copy of hepatitis B virus (HBV) genome without the core gene and expressing hepatitis B surface antigen (HBsAg) were crossed with C3H/He mice. The F1 hybrids (approximately 50% HBV positive and approximately 50% HBV negative) were treated with a single dose of diethylnitrosamine (NDEA) or p-dimethylaminoazobenzene (DAB) given at 7 days of age, or were untreated. Mice were kept under observation without further treatments until 30 weeks old and then killed. Stereological analysis of liver nodules and estimations of their size distribution demonstrated a significative enhancing effect of HBV transgene in both NDEA- and DAB-induced hepatocarcinogenesis in male mice. Hepatocellular adenomas and carcinomas were also more frequent in NDEA-treated HBV-positive than HBV-negative male mice. Female mice showed a lower tumorigenic response than males without significant differences between groups of HBV-positive and HBV-negative mice. It is proposed that the presence of the transgene enhanced carcinogen-induced hepatocarcinogenesis.

Animals↗

PubMed1989

Cycloheximide increases endogenous retroviral RNA levels in murine liver and lung.

The expression of moloney murine leukemia virus (Mo-MuLV), intracisternal A particle (IAP), virus-like 30S sequence (VL30), early transposon (ET) endogenous retroviral sequences was analysed in the liver of untreated C3Hf, C57BL/6J and AKR mice, and in the lungs of untreated A/J, BALB/c, C3Hf and C57BL/6J mice. C3Hf mice are genetically susceptible to hepatocarcinogenesis, whereas the other strains are resistant. A/J and BALB/c mice are genetically susceptible to lung carcinogenesis, whereas the other strains are resistant. Both in liver and lung tissues we found differences between murine strains in the pattern of basal retrovirus expression. The effect of inhibition of protein synthesis on the levels of retroviral mRNAs was studied in the same tissues and strains 3 h following in vivo cycloheximide treatment. Cycloheximide treatment increased the liver and lung levels of virus Mo-MuLV, IAP, ET related transcripts in a strain dependent way, whereas VL30 mRNA levels increased in both tissues of all strains examined. These results suggested the existence of labile proteins that regulate the abundance of specific retroviral mRNAs in murine liver and lung in a strain specific fashion. No clear relationships between pattern of retrovirus expression and genetical susceptibility to hepatocarcinogenesis was found. The strains genetically resistant to lung carcinogenesis (C3Hf, C57BL/6J) showed higher lung basal levels and higher cycloheximide inducibility of mRNAs homologous to Mo-MuLV than the susceptible strains (A/J, BALB/c).

Animals↗

PubMed1989

Major urinary protein as a negative tumor marker in mouse hepatocarcinogenesis.

A cDNA clone isolated by differential screening of a mouse liver cDNA library using RNA probes from normal adult liver and from hepatocellular tumors showed, on northern blot analysis, a single transcript of 1 kb present at high levels in normal adult mouse liver but at 15- to 100-fold reduced levels in spontaneous and p-dimethylaminoazobenzene- or urethan-induced liver tumors. The transcript, which was absent in two-wk-old mouse liver, is coded by a developmentally regulated gene. Nucleotide sequence analysis demonstrated that the isolated clone encoded a major urinary protein (MUP). Immunocytochemistry analysis, using a goat antibody to MUP on histologic liver sections containing diethylnitrosamine-induced liver nodules, showed that the decrease in MUP levels also occurred in microscopic nodules. Therefore, MUP decrease represents an early event in the development of mouse liver tumors, and it may be used as a tumor marker in mouse hepatocarcinogenesis.

Alpha-Globulins↗

PubMed1989

High frequency of activation of tyrosine kinase oncogenes in human papillary thyroid carcinoma.

We had previously detected a transforming oncogene, designated PTC, in 25% of 20 papillary thyroid carcinomas. In order to characterize further the transforming activity of this tumour histotype, a new panel of tumour specimens from 16 patients was analysed by using a modified calcium phosphate-DNA coprecipitation transfection protocol. Tumour DNA from 10 patients (62%) displayed a transforming activity due to activation of three different oncogenes identified in four cases as PTC, in four cases as TRK, and in two cases as N-RAS. The same structural alterations of PTC and TRK (gene rearrangements) as well as of N-RAS (point mutation) detected in the NIH3T3 transformants, were also found in the original tumour DNAs, thus indicating that their activation was not due to transfection procedures. Since both PTC, a novel rearranged form of RET, and TRK display a tyrosine protein kinase activity, it is proposed that the activation of this class of oncogenes is specifically involved in the pathogenesis of papillary thyroid cancer.

Animals↗

PubMed1987

Factors influencing the expression of endogenous retrovirus-related sequences in the liver of B6C3 mice.

The expression of RNA transcripts from three families of endogenous retrovirus-related sequences was investigated during liver cell proliferation in B6C3 mice. Treatment with a single dose of the liver mitogen and promoter of mouse hepatocarcinogenesis 1, 4-bis[2-(3,5-dichloropyridyloxy)]benzene (TCPOBOP), or with carbon tetrachloride (CCl4), induced liver cell proliferation at days 2 and 3 after treatment. Both of these treatments led to a marked increase in Moloney murine leukemia virus-related 6 kilobase RNAs, which were most abundant at day 1 after TCPOBOP treatment and at day 2 after CCl4. Intracisternal A particle-related 6 kilobase RNAs were markedly increased at days 1 and 2 after TCPOBOP and at days 1, 2, and 3 after CCl4. VL30-related transcripts were slightly decreased after TCPOBOP, but they were markedly increased at days 1 and 2 following CCl4. The livers of 15-day-old untreated mice contained about a 3-fold higher level of Moloney murine leukemia virus-related RNAs than adult liver. Intracisternal A particle-related 6-kilobase transcripts were present at 3-fold higher abundance in 7-day-old than in 15-day-old or adult liver. RNAs homologous to VL30 were detected at about the same levels in infant as well as adult livers. Inhibition of protein synthesis by the administration of cycloheximide to adult mice caused a marked increase in the amount of Moloney murine leukemia virus-, intracisternal A particle-, and VL30-related RNAs in the livers of the treated mice, suggesting the existence of labile proteins that normally regulate the abundance of these transcripts. We postulate that the amounts of these putative regulatory proteins vary during both normal development and carcinogenesis and also in response to specific agents that induce liver cell proliferation.

Animals↗

PubMed1987

Genetic susceptibility to murine hepatocarcinogenesis is associated with high growth rate of NDEA-initiated hepatocytes.

The murine hybrids (C57BL/6J X C3Hf)F1 (B6C3) and (C57BL/6J X BALB/c)F1 (B6C), which have a high and low spontaneous and induced incidence of hepatocellular tumors, respectively, were treated with a single dose of NDEA at 1 week of age followed by TCPOBOP, a phenobarbital-like promoter of liver carcinogenesis, or by vehicle, and sacrificed at 30 weeks of age. The frequency per liver of hepatocellular nodules was similar in the two hybrids. However, in male mice the mean volume of nodules was about 10-fold greater in B6C3 than in B6C mice receiving NDEA followed by vehicle, and the treatment with TCPOBOP after NDEA stimulated nodule growth, with a much greater response in B6C3 mice. In female mice no differences in the mean volume of nodules were seen between hybrids after NDEA and vehicle, whereas upon NDEA and TCPOBOP treatment the mean volume of nodules was 25-fold greater in B6C3 than in B6C females. In addition, a few hepatocellular adenomas and carcinomas were observed, mostly in animals treated with NDEA and TCPOBOP, and they were 3-fold more numerous among B6C3 than B6C mice. TCPOBOP alone induced the same biochemical and hyperplastic effects in the liver of both hybrids. Using DNA probes homologous to Moloney murine leukemia virus, intracisternal A particle and virus-like 30S sequences, no correlation was apparent between the expression of any of these endogenous retroviral families and the strain susceptibility to hepatocarcinogenesis. We hypothesize that the different susceptibility to hepatocarcinogenesis between B6C3 and B6C mice is related to a higher growth rate of B6C3 than B6C initiated liver cells.

Adenoma↗

PubMed1987

Effects of phenobarbital and 1,4-bis[2-(3,5-dichloropyridyloxy)]benzene on differentiated functions in mouse liver.

The promoters of murine hepatocarcinogenesis phenobarbital (PB) and 1,4-bis[2-(3,5-dichloropyridyloxy)]benzene (TCPOBOP) given to adult C3Hf female mice increased the content of total liver DNA by 1.6-1.8-fold each week after the beginning of treatment. Both compounds increased the aminopyrine-N-demethylase activity, decreased the glucose 6-phosphatase (G6Pase), alkaline phosphodiesterase I and alkaline phosphatase specific activities, but did not modify the gamma-glutamyltransferase levels. Both compounds decreased the abundance of tyrosine aminotransferase- and metallothionein I-related RNA transcripts. These findings confirmed the PB-like activity of TCPOBOP and showed that both chemicals had a pleiotropic effect on mouse liver, that was not limited to stimulation of drug metabolism, but also affected other hepatocyte functions.

Animals↗

PubMed1987

Two-stage liver carcinogenesis in the mouse.

A two-stage protocol for studying liver carcinogenesis was applied to the mouse. The protocol includes the treatment of 7-day-old mice with a single low dose of an initiating agent (diethylnitrosamine, NDEA), promotion starting after weaning and lasting about 20 weeks, and histologic analysis, at 30 weeks of age, of hepatocellular nodules on H&E stained sections. A stereologic analysis of results allows the evaluation of nodule frequency and size. Using this protocol in B6C3 and B6C mice, we have identified the promoting activity of the phenobarbital-like enzyme inducer, 1,4-bis[2-(3,5-dichloropyridyloxy)]benzene (TCPOBOP), which was found to be a strong hyperplaseogenic agent for mouse liver. These studies also indicated that the different susceptibility to hepatocarcinogenesis in B6C3 and B6C mice may be related to a higher susceptibility of B6C3 than B6C initiated liver cells to growth stimulation. A long-term study showed that B6C mice have a low incidence of spontaneous liver tumors but are susceptible to chemical hepatocarcinogenesis and, therefore, they may be an alternative model to B6C3 mice in carcinogenesis bioassays.

Animals↗

PubMed1986

Enhancing effects of carbon tetrachloride in mouse hepatocarcinogenesis.

The enhancing effects of 4 or 8 necrogenic doses of carbon tetrachloride (CCl4) on hepatocarcinogenesis were studied in female B6C3F1 mice previously treated with a single dose of N-nitroso-N-diethylamine (NDEA) at 7 days of age. The CCl4 treatments were given every other week and started either after weaning or at 18-26 weeks of age, and the animals were observed until 36 weeks of age. The number and size of hepatocellular nodules were then scored and analysed. Hepatocellular nodules were not observed in mice receiving either 4 or 8 CCl4 treatments without NDEA initiation. Both 4 and 8 CCl4 treatments promoted NDEA-initiated hepatocarcinogenesis, increasing nodule size but not nodule frequency. Eight CCl4 doses were more effective than 4 and gave the greatest increase in nodule size when administered from 18 to 32 weeks of age. In an additional experiment, 3 mice bearing hepatocellular nodules induced by a single infantile NDEA treatment were administered CCl4 once and killed 52 h later. Nine neoplastic nodules were examined and found to be resistant to the CCl4 induced necrosis, although cells in the nodules were actively dividing at the same rate as in the regenerating surrounding normal liver parenchyma. The ability of a few necrogenic CCl4 doses to enhance hepatocarcinogenesis may be related to a differential cytotoxicity on neoplastic and normal hepatocytes and to a similar mitogenic stimulus on both cell types.

Animals↗

PubMed1986

Expression of retroviral sequences and oncogenes in murine hepatocellular tumors.

The expression of endogenous retroviral sequences and of three cellular oncogenes was examined in three hepatocellular adenomas and in four carcinomas induced in male C57BL/6JDp X C3Hf/Dp F1 (hereafter called B6C3F1) mice by a single dose of nitrosodiethylamine, in five carcinomas that arose spontaneously in male C3Hf mice, and in the livers of normal age-matched control mice. In all of these adenomas and carcinomas, there was increased expression of Moloney murine leukemia virus- and intracisternal A particle-related sequences. The retrovirus-like VL30 sequence was expressed at significant levels in the normal liver of these mice and increased expression of this sequence was found in only 4 of the 12 tumors examined. Expression of endogenous mouse mammary tumor virus-related sequences was not detected in the normal livers or in any of the liver tumors. With respect to cellular oncogenes, increased expression of c-myc was seen in all of the B6C3F1 tumors. Two of five normal liver samples and all of the tumors of the C3Hf mice displayed significant expression of c-myc. There was a slight increase in expression of c-Ha-ras in some of the tumors. Increased expression of c-fos was found in only 1 of the 12 tumors. Taken together, these studies indicate that both carcinogen-induced and spontaneous liver tumor formation in mice is associated with abnormalities in the expression of endogenous retrovirus-related DNA sequences and also specific cellular oncogenes.

Animals↗

PubMed1985

Promoting effects of 1,4-bis[2-(3,5-dichloropyridyloxy)]benzene in mouse hepatocarcinogenesis.

The effects of phenobarbital (PB) and 1,4-bis[2-(3,5-dichloropyridyloxy)]benzene (TCPOBOP) on liver hyperplasia, induction of microsomal enzyme activities, and two-stage hepatocarcinogenesis were evaluated in B6C3F1 female mice. For 4 weeks four groups of mice received PB (500 p.p.m. in the drinking water), TCPOBOP (3 mg/kg i.p. once every week), PB together with TCPOBOP or corn oil vehicle i.p. TCPOBOP induced liver hyperplasia and hypertrophy and increased p-nitroanisole-O-demethylase and aminopyrine-N-demethylase more than PB. Neither chemical changed UDPG-transferase activity. The association of PB and TCPOBOP gave the same effects as TCPOBOP alone. Other four groups of mice were treated with N-nitroso-N-diethylamine at 7 days of age and then, starting from 8 weeks of age, received the above specified weekly treatments for 20 weeks and were then sacrificed. Hepatocellular nodules greater than 150 microns were found in all animals of all groups. Due to increased size of the liver compared to controls, the number of nodules/cm3 decreased after PB and TCPOBOP treatments given alone or together; however the mean volume of nodules and the percentage of liver volume occupied by nodules increased after TCPOBOP but not after BP treatment, and the association of PB and TCPOBOP was even more effective than TCPOBOP alone. Hepatocellular adenomas greater than 2.4 mm in diameter were observed in 5 of 10 TCPOBOP-treated mice (total of 11 nodules) and in 5 of 11 mice that received PB plus TCPOBOP (total of 15 nodules). Hepatocellular carcinomas were seen in one mouse treated with PB and in three mice given PB and TCPOBOP.

Adenoma↗