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G Della Porta

Publications and source records attributed to G Della Porta.

At least 37 records · Page 2Linked to original sources
PubMed1992

Cytogenetic and molecular genetic characterization of papillary thyroid carcinomas.

A combined cytogenetic and molecular analysis was performed on 11 cases of papillary thyroid carcinoma. A simple karyotypic abnormality was detected in five tumors, whereas six had no apparent chromosome change. In four of five rearranged cases the presence of a specific chromosomal abnormality involving chromosome 10 (cases 1 and 2) and chromosome 1 (cases 3 and 4) was associated with the rearrangement of two protooncogenes: RET and NTRKI (formerly trk), respectively, with different donor genes. Moreover, the chromosomal localization of the involved genes and the type of chromosomal change observed suggested that RET and NTRKI activation occurred by intrachromosomal rearrangements. The six cases with normal karyotype did not show RET or NTRKI activation. These findings suggest that a combined cytogenetic and molecular approach would be useful in understanding the pathogenesis of thyroid neoplasia.

Blotting, Southern↗
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

A t(2;3)(q12-13;p24-25) in follicular thyroid adenomas.

We report the cytogenetic analysis of five cases of follicular thyroid adenoma. In two of them, we observed an identical t(2;3)(q12-13;p24-25) as a unique chromosome change. A third case showed a hyperdiploid karyotype with trisomies of chromosomes 7 and 12. Two cases had a normal diploid karyotype. These changes could define subgroups of follicular adenomas endowed with different malignant potential.

Adenocarcinoma↗
PubMed1992

HPV DNA in intraepithelial neoplasia and carcinoma of the vulva and penis.

Surgical specimens of 15 patients with early and 12 patients with advanced squamous cell carcinoma of the vulva and the penis were examined for the presence of human papillomavirus (HPV) type 6, 11, 16, and 18 DNA by Southern blotting (SB) and polymerase chain reaction (PCR) analysis. By SB, HPV type 16 DNA was detected in all early carcinomas and 2 of 12 cases of advanced squamous cell carcinoma (ISCC) of the vulva and penis. PCR revealed HPV DNA in four additional cases of vulvar and penile ISCC negative by SB. Three cases contained HPV16 and one HPV18. Two cases of vulvar and penile Buschke-Löwenstein (BL) tumor with malignancy and one case of vulvar verrucous carcinoma were also examined by both techniques. While BL tumors were associated with DNA of HPV6 or 11, no HPV association was found for verrucous carcinoma. Our results confirm that the detection rate of HPV DNA in early vulvar and penile carcinomas is much higher than in invasive carcinomas. In addition, we have shown that in the lower genital tract, 50% of cases of ISCC are HPV16 correlated. The absence of HPV DNA (types 6, 11, 16, and 18) in the remaining 50% of cases of ISCC thus suggests that vulvar and penile ISCC may have more than one pathogenetic pathway.

Base Sequence↗
PubMed1992

Ret oncogene activation in human thyroid neoplasms is restricted to the papillary cancer subtype.

We have recently reported the activation of a new oncogene in human papillary thyroid carcinomas. This oncogene, papillary thyroid carcinoma (PTC), is a novel rearranged version of the ret tyrosine-kinase protooncogene. Thyroid neoplasms include a broad spectrum of malignant tumors, ranging from well-differentiated tumors to undifferentiated anaplastic carcinomas. To determine the frequency of ret oncogene activation, we analyzed 286 cases of human thyroid tumors of diverse histologic types. We found the presence of an activated form of the ret oncogene in 33 (19%) of 177 papillary carcinomas. By contrast, none of the other 109 thyroid tumors, which included 37 follicular, 15 anaplastic, and 18 medullary carcinomas, and 34 benign lesions, showed ret activation.

Base Sequence↗
PubMed1992

Human papillomavirus genomes in male urethral cells.

Sixty-four samples of urethral cells from male sexual partners of women with genital human papillomavirus (HPV) infection were analyzed for the presence of HPV types 6, 11, 16, and 18 by polymerase chain reaction (PCR) followed by slot blot hybridization. Additional samples from 37 of these subjects were analyzed for the presence of viral cytopathic effects by conventional cytology. By PCR, HPV DNA was detected in 21% (14/64) of samples. By cytology, 16% (6/37) of the samples showed cellular changes consistent with HPV infection. Polymerase chain reaction and cytology results were concordant for presence and absence of HPV in 5 and 28 cases, respectively. Three additional HPV-positive cases were obtained with PCR in the cytologically negative samples. The cytologic abnormalities were found to be associated with the presence of both low-risk HPV types and meatal acetoreactivity. On the contrary, HPV DNA positivity by PCR was unrelated to viral type and peniscopic findings. Urethral HPV infection was detected by PCR in 30% of males with visible penile lesions and in 18% of those without. These results indicate that PCR analysis of urethral samples is a helpful adjunct to cytology for the detection of HPV DNA in absence of cytologic evidence of infection.

Base Sequence↗
PubMed1992

Identification of the product of two oncogenic rearranged forms of the RET proto-oncogene in papillary thyroid carcinomas.

In papillary thyroid carcinomas, we have identified two tumor-specific rearrangements of the RET proto-oncogene leading to the formation of different transforming fusion products sharing the tyrosine kinase (tk) domain of the proto-oncogene and designated ptc-1 and ptc-2. We have analysed ptc-1 and ptc-2 products by immunoprecipitation with specific anti-RET antibodies followed by immunoblotting with the same reagent or with antibodies specific for phosphotyrosine (P-tyr) residues. The anti-RET antibodies were reactive with 64-kDa (p64ptc-1) and 81-kDa (p81ptc-2) proteins from lysates of ptc-1 and ptc-2 transformed cells, respectively, and identified two proteins of 140 kDa and 160 kDa from extracts of SK-N-SH, a neuroblastoma cell line previously shown to express two differently glycosylated forms of the normal RET product. The anti P-tyr antibodies, while detecting the same p64ptc-1 and p81ptc-2 proteins from ptc-1 and ptc-2 extracts, did not show any specific band in the neuroblastoma lysates. An additional set of experiments led us to conclude that, whereas the normal product of the RET proto-oncogene is a membrane-associated receptor-like molecule not intrinsically phosphorylated on tyrosine, both oncogenic forms of RET, ptc-1 and ptc-2, are constitutively phosphorylated on tyrosine, display an 'in vitro' autophosphorylation activity, are translocated from the membrane to the cytoplasm and are apparently unaffected by protein kinase C modulation.

3T3 Cells↗
PubMed1992

TRK-T1 is a novel oncogene formed by the fusion of TPR and TRK genes in human papillary thyroid carcinomas.

We have recently reported the frequent activation of the TRK oncogene in human papillary thyroid carcinoma. In this paper we describe the isolation and characterization of one of the thyroid TRK oncogenes, designated TRK-T1. A 1746-bp-long cDNA was isolated from a library derived from a primary transformant. The cDNA was able to induce foci in NIH3T3 cells. Sequence analysis revealed that TRK-T1 is created by an intrachromosomal rearrangement that juxtaposes the 5' end of the TPR gene to the TRK tyrosine kinase domain. The resulting hybrid mRNA contains 598 nucleotides of the TPR gene and 1148 nucleotides of the TRK proto-oncogene. TRK-T1 mRNA encodes a protein of 55 kDa reacting with antibodies against the carboxy terminus of the proto-TRK protein. We show also the involvement of TPR in the generation of another TRK-T oncogene.

3T3 Cells↗
PubMed1992

DNA methylation of coding and non-coding regions of the human H-RAS gene in normal and tumor tissues.

To study a possible role of DNA methylation in the regulation of expression of the human H-RAS gene in vivo, 41 samples of different normal tissues and 33 tumors of various histotypes were analysed for DNA methylation. In a subset of normal tissues the RNA expression was also examined. The promoter region of the gene showed the features of a CpG island being CpG rich and unmethylated in all the normal tissues and tumors. The coding region displayed an intermediate level of methylation in the majority of normal and tumor tissues. Among the normal tissues only thymus DNA was found to be hypermethylated, while testes and sperm cells DNAs were hypomethylated. The 3' region was found to be completely methylated only in sperm cells and was never completely demethylated. The majority of the tissues showed an intermediate level of methylation, and a certain tissue specificity emerged by comparing tissues of the same and different histotypes. However, the overall methylation of both coding and 3' regions did not correlate with the levels of tissue-specific RNA expression. In heterozygous individuals, allelic methylation of the 3' region showed either perfectly balanced or slightly unbalanced methylation of the two alleles in normal tissues, while an allele-specific methylation was found in 5 out of 12 fresh tumor samples.

Alleles↗
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

Prognostic significance of HER-2/neu expression in breast cancer and its relationship to other prognostic factors.

Archival surgical specimens from 1,210 female breast cancer patients treated between 1968 and 1971 and with a 19-year follow-up were reanalyzed with special reference to several parameters, such as size of the primary tumor, axillary nodal involvement, histologic grade, degree of inflammatory infiltrate (LPI) of the tumor and expression of the neu oncoprotein (p185) as detected by immunohistochemistry. In a multifactorial analysis the 4 former factors were found to be independent prognostic parameters. Over-expression of p185 was found to be related to tumor size and grade and to LPI but not to pathologic nodal status. Over-expression of p185 showed a negative impact upon survival in node-positive but not in node-negative patients. However, in the subset of node-negative patients without LPI, p185 over-expression showed the same correlation with a poor prognosis as in node-positive patients. In contrast, in node-negative and LPI-positive patients, p185 over-expression correlated with a good prognosis. Also, the prognosis of patients with positive nodes, presence of LPI and no p185 over-expression was similar to that of patients with negative nodes, absence of LPI and p185 over-expression.

Age Factors↗
PubMed1991

Activation of ras oncogenes and expression of tumor-specific transplantation antigens in methylcholanthrene-induced murine fibrosarcomas.

The DNA of 22 fibrosarcomas, newly induced in BALB/c mice by subcutaneous doses of 3-methylcholanthrene (3-MCA), was tested in NIH 3T3 transformation assay. Activation of K-ras and N-ras was found in 7 and 3 cases respectively. No H-ras activation was detected. Polymerase chain reaction and oligonucleotide hybridization performed on the DNA of the 22 sarcomas revealed 5 cases of K-ras mutation at codon 12, 3 at codon 13 and 1 at both codons. One case of K13 mutation was not detectable by transfection. Three cases of mutation at codon 61 of N-ras were also found, one of which was simultaneous with a K12 mutation. Tumor-specific transplantation antigens (TSTA) were assessed in the 22 original tumors. Altogether 16 sarcomas were immunogenic, with the highest frequency of TSTA+ tumors (10/11 and 5/6) in the groups given 1.0 and 0.1 mg of 3-MCA respectively, the lowest (1/5) in that with 0.01 mg of carcinogen; ras mutations occurred in the DNAs of 11 out of the 16 TSTA+ sarcomas, but none of the DNAs of the 6 TSTA- tumors showed ras mutation. The results suggest that 3-MCA-induced transformation of subcutaneous fibroblasts can involve mutations in codons 12, 13 or 61 of K- and N- but not H-ras gene and that such mutation is accompanied by the expression of TSTA.

Animals↗
PubMed1991

Cytogenetic abnormalities and overexpression of receptors for growth factors in normal bronchial epithelium and tumor samples of lung cancer patients.

A cytogenetic analysis was performed on direct preparations and short-term cell cultures of lung tumor and normal bronchial epithelium of 19 patients carrying either a first or a second primary lung cancer. In 9 tumors (6 squamous cell carcinomas, 1 adenocarcinoma, 1 mucoepidermoid carcinoma, and 1 small cell lung carcinoma) successfully analyzed, pseudodiploid and hyperdiploid karyotypes were observed with a heterogeneous pattern of chromosome abnormalities but with a consistent involvement (5 cases) of the short or the long arm of chromosome 3. The normal bronchial epithelial cells had a normal karyotype in 11 patients, whereas in 6 patients clonal and nonclonal chromosomal abnormalities were observed. Involvement of chromosome 7 was present in 4 cases. In addition, overexpression of the growth factor receptors, epidermal growth factor receptor and HER-2/neu, was found in 9 of 18 tumors and in 6 of 13 bronchial epithelium samples. These findings suggest that early genetic lesions could be present in the normal bronchial epithelial cells that are the target of further complex and multiple genetic changes occurring during the pathogenesis of lung cancer.

Aged↗
PubMed1991

The human tropomyosin gene involved in the generation of the TRK oncogene maps to chromosome 1q31.

The chromosomal localization of hTMnm, a gene coding for a cytoskeletal tropomyosin non-muscle isoform involved in the activation of the TRK proto-oncogene in various human tumors, was determined by Southern blot analysis of a panel of human-rodent somatic cell hybrids. Using as a probe an Alu-free intronic fragment related to the tropomyosin sequence fused to the TRK tyrosine kinase domain, the hTMnm gene was assigned to the long arm of chromosome 1. Subsequently, in situ hybridization of the same probe to human metaphase chromosomes localized the hTMnm gene to 1q31. Since we have recently assigned the TRK locus to chromosome 1q32-q41, the generation of the hybrid transforming sequence tropomyosin-TRK may be due to an intrachromosomal rearrangement of the long arm of chromosome 1.

Blotting, Southern↗
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↗