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Biomedical subjects

M Colombi

Publications and source records attributed to M Colombi.

At least 37 records · Page 2Linked to original sources
PubMed1996

Frequent TP53 gene alterations (mutation, allelic loss, nuclear accumulation) in primary non-small cell lung cancer.

Mutations of the TP53 tumour suppressor gene have been reported for many human cancers. A variety of TP53 mutations have also been reported for both primary non-small cell lung cancer (NSCLC) and associated metastases. To assess the pathogenetic significance of TP53 gene alterations in NSCLC, 24 paired samples of primary NSCLC and the corresponding normal lung tissue were analysed for mutations of the TP53 gene (exons 5-8) using exon-specific PCR, single-strand conformation polymorphism PCR (SSCP-PCR) and direct DNA sequencing; for p53 protein accumulation by immunohistochemistry and for 17p allelic loss using restriction fragment length polymorphism (RFLP) probes on Southern blots and amplified fragment length polymorphism-PCR. TP53 point mutations were observed in 9/24 (38%) tumours encompassing a total of 14 mutations. Two tumours displayed the same double mutation while a third harboured four different mutations. Seventeen of 24 NSCLCs (71%) overexpressed p53 protein and all 17 immunopositive tumours (100%) showed a mutation and/or allelic loss at the D17S30 locus. Of the 17 NSCLCs informative at the DS17S30 locus, 10 (59%) showed allelic loss, of which five (50%) were also mutated on the remaining TP53 allele. These results suggest that TP53 gene alterations are involved in the pathogenesis of primary NSCLC and that such alterations may serve a selective role in the development of NSCLC by diminishing the apoptotic potential of bronchial epithelial cells heterozygous for a TP53 point mutation. This may also explain the accumulation of multiple TP53 point mutations in 3/24 of our NSCLC samples.

Alleles↗
PubMed1996

Identification of two splicing mutations in the collagen type VII gene (COL7A1) of a patient affected by the localisata variant of recessive dystrophic epidermolysis bullosa.

Collagen type VII gene (COL7A1) has been demonstrated to be altered in several variants of dystrophic epidermolysis bullosa (DEB), with either recessive or dominant mode of inheritance. We have identified two mutations in a patient affected by a localisata variant of recessive DEB (L-RDEB), which is characterized by the less severe phenotype of the syndrome. These mutations are the first splicing mutations so far described for COL7A1 in DEB. One mutation is a paternally inherited A-->G transition at position -2 of the donor splicing site of intron 3, which results in three aberrant mRNAs, depending on the skipping of exon 3, the usage of a cryptic donor site inside exon 3, or the maintenance of intron 3. The second mutation is a maternally inherited G-->A transition at position -1 of the donor splicing site of intron 95, which induces the activation of a cryptic donor site 7 nt upstream the normal site and gives rise to a deleted mRNA, in addition to the normal one. All aberrant mRNAs show a shift of the reading frame, thus generating premature termination codons of translation. Allele-specific analysis of the transcripts has shown that the maternal mutation does not completely abolish the correct splicing of COLVII pre-mRNA, thus allowing, in the patient, the synthesis of a certain level of a functional protein. This result is compatible with the mild clinical L-RDEB phenotype observed in our patient.

Adolescent↗
PubMed1995

Genomic organisation and chromosomal localisation of the gene encoding human beta adducin.

Adducin (ADD) is a heterodimeric protein of the membrane skeleton with subunits of 103 (alpha) and 97 kDa (beta). It promotes the assembly of the spectrin-actin network. We have previously shown that one point mutation in each of the alpha and beta rat ADD-encoding genes is associated with blood pressure variation in an animal model for hypertension, the Milan hypertensive strain of rats, probably due to a change in the phosphorylation pattern. In fact, the rat mutations, Y to F for alpha and R to Q for beta, are located, respectively, in a tyrosine kinase and a protein kinase A phosphorylation site. We have now determined, for the human beta-ADD-encoding gene, its chromosomal localisation, exon-intron organisation and alternative splicing patterns. We report here that human beta-ADD is localised on chromosome 2 and we also show a characteristic 3' end alternative splicing of the beta-ADD RNA that generates two distinct beta-ADD families, namely ADD 63 and 97; both of them in turn present a very complex differential splicing pattern in the internal exons.

Alternative Splicing↗
PubMed1995

Plasminogen activators in nude mice xenotransplanted with human tumorigenic cells.

Nude mice have been subcutaneously inoculated with human tumorigenic fibrosarcoma cells (HT-1080) producing urokinase-type plasminogen activator (u-PA) or with human tumorigenic melanoma cells (G-361) producing tissue-type plasminogen activator (t-PA). Human u-PA (hu-PA) and t-PA (ht-PA) were found in the plasma and in the tumors of mice injected with HT-1080 or G-361 cells, respectively. Metastases containing ht-PA were observed in different organs of mice transplanted with G-361 cells, while mice injected with HT-1080 cells did not develop metastases. These data would suggest a relationship between the metastatic potential of G-361 cells and t-PA. The parallel increase of the levels of endogenous murine PAs (m-PA) activities might play a crucial role in the early stages of tumor growth and metastasis, since the biological effects of the PAs produced by the transplanted tumor cells can not be dissociated from those of the PAs induced in the host.

Animals↗
PubMed1995

Angiokeratoma corporis diffusum and arteriovenous fistulas with dominant transmission in the absence of metabolic disorders.

BACKGROUND: A three-generation family with members affected by angiokeratoma corporis diffusum (ACD) and arteriovenous fistulas of the legs is described. Our purpose was to investigate possible lysosomal storage defects previously described in association with ACD. OBJECTIVE: Results of physical examination of both affected and unaffected family members were otherwise normal as was the life span. The inheritance pattern of both ACD and arteriovenous fistula traits was autosomal dominant, with variable expressivity and incomplete penetrance. Microscopic examination of ACD lesions showed dilated capillaries without vacuolation of cells. Ultrastructural studies failed to reveal lysosomal abnormalities. Normal levels of alpha-galactosidase, beta-galactosidase, alpha-fucosidase, and alpha-sialidase were detected in peripheral blood leukocytes and skin fibroblasts. CONCLUSIONS: The association of autosomal dominant ACD and arteriovenous fistulas might represent a novel syndrome. However, pathogenesis of these lesions remains unknown.

Adolescent↗
PubMed1994

Identification of genes differentially expressed in normal lung and non-small cell lung carcinoma tissue.

Using a magnet-assisted subtraction technique, 17 complementary DNA (cDNA) clones were isolated that were expressed in the normal lung but were decreased or lost in the corresponding tumor tissue of a nonsmall cell lung carcinoma patient. The lack of expression of six magnet-assisted subtraction technique cDNA clones in three additional non-small cell lung carcinoma cases indicates their possible relevance for non-small cell lung carcinoma. Two cDNA clones revealed homology to genes specifically expressed in lung, i.e., pulmonary surfactant-associated protein B and the receptor for advanced glycosylation end products of proteins. Three cDNA clones showed identity to cDNA sequences encoding calmodulin-like protein, glutamine synthetase, and cytoskeletal beta-actin. One cDNA clone is identical to a recently described human expressed sequence tag whose gene is still unknown.

Base Sequence↗
PubMed1994

RT-PCR detection of fibronectin EDA+ and EDB+ mRNA isoforms: molecular markers for hepatocellular carcinoma.

Alternative splicing of fibronectin pre-mRNA has been shown to be independently regulated at the EDA and EDB regions in a tissue and developmental stage-specific manner. In this study, RT-PCR approaches were developed for the detection of EDA and EDB FN mRNA isoforms in hepatocarcinoma cells (SK-Hep-I) grown in vitro and in human liver biopsies. While EDA+ and EDB+ isoforms were not present in control adult liver, they were detectable in the hepatocarcinoma cells and in fetal liver. The RT-PCR analysis, extended to biopsies of malignant and non-malignant hepatic tissues, showed that FN mRNAs containing the EDA and EDB sequences were present in the 14 hepatocellular carcinomas (HCCs) tested but absent in the non-tumorous liver tissues (i.e., normal parenchyma, non-specific reactive and chronic hepatitis, steatosis). The EDB+ FN mRNA isoforms were also detected in 3 cases of benign neoplasm (hepatocellular adenoma, HCA, I; nodular focal hyperplasia, NFH, 2), while the EDA+ was only detectable in I of the 2 cases of NFH. In addition, both EDA+ and EDB+ isoforms were expressed in 5 out of 9 cirrhotic livers surrounding the tumors. This molecular analysis, which can also be performed on small liver biopsies (2 mg), may therefore be a useful additional tool in the diagnosis of HCC.

Alternative Splicing↗
PubMed1994

Correction of the defective extracellular matrix of Ehlers-Danlos syndrome skin fibroblasts by dexamethasone.

Skin fibroblasts derived from Ehlers-Danlos syndrome (EDS) patients lack an organized extracellular matrix (ECM) of fibronectin (FN) and often show an accumulation of cytoplasmic FN. The treatment of EDS cells of different types (I to VIII) with 10(-7) M dexamethasone (dex), as well as cocultivation with control fibroblasts, induced in most cases the assembly of a FN-like ECM. The study of FN mRNA expression by dot-blot hybridization and of FN released into the culture media of EDS cells showed that the correction of the defective FN-ECM of EDS cells by dex treatment is associated in most cases with an increase of FN mRNA synthesis and of secreted FN.

Cells, Cultured↗
PubMed1994

Uncommon clinical presentation of a lymphocytic lymphoma of intermediate differentiation in a patient with systemic sclerosis.

The association of systemic sclerosis (SSc) and non-Hodgkin lymphoma is a rare event and its pathogenetic mechanism remains to be clarified. We describe a previously unreported association of SSc with a lymphocytic lymphoma of intermediate differentiation (IDL), involving the gastrointestinal tract, gallbladder and one salivary gland. Whereas the morphological, immunological and cytogenetic features were typical of IDL, the extensive extranodal involvement and the association with an autoimmune disorder were suggestive of two other lymphomas of mantle lineage: mucosa-associated lymphoid tissue (MALT) lymphoma and monocytoid B-cell lymphoma (MBCL).

Female↗
PubMed1993

The type III-9 repeat of human fibronectin is encoded by a single exon which is not alternatively spliced.

Type III homologies of human fibronectin are generally encoded by two exons, with the exception of the ED-A and ED-B repeats which are encoded by a single exon undergoing alternative splicing. We report that also the type III-9 homology is encoded by a single exon. Further more, RT-PCR analysis, performed on mRNA purified from fetal and adult tissues and from normal and tumor-derived cell types, showed that the III-9 region is not undergoing alternative splicing in all samples tested.

Adult↗
PubMed1993

Loss of heterozygosity on chromosome 11p13 in primary bladder carcinoma.

Although the occurrence of bladder cancer is common, the molecular events underlying the pathogenesis of this cancer remain ill-defined. A loss of heterozygosity (LOH) at specific chromosomal loci may predispose individuals to the development of bladder cancer but this has not been examined in detail. Furthermore, the role that deletion or inactivation of putative tumour suppressor genes might play in the genesis of bladder cancer has not been established. In this study, allelic deletion analysis on the short arm of chromosome 17 of patients with primary bladder tumours failed to show deletion at 17p13 (0/7), a region known to contain the p53 tumour suppressor gene. Chromosome 11p15 showed allelic deletion at the IGF2 locus (2/7: 29%) and the PTH locus (1/11: 9%). However, no deletion was observed at the CALCA locus (0/6). LOH at 11p13, a region containing the Wilm's tumour suppressor gene (WT1), was also studied. Analysis of LOH at 11p13 showed deletion at the CAT locus (13/18: 72%), the delta J/D11S414 locus (5/15: 33%), the WT1 locus (7/14: 50%) and the FSHB locus (6/16: 38%). The significance of these findings is discussed.

Alleles↗
PubMed1993

Quantitative evaluation of mRNAs by in situ hybridization and image analysis: principles and applications.

We describe an image analysis (IA) program that has been developed for the quantitative evaluation of mRNA evidenced by in situ hybridization (ISH) with radiolabeled probes in cultured cells and tissue sections. ISH-IA allowed the detection and quantitative evaluation of mRNA expressed by heterogeneous in vitro cultured cells. This method, when combined with dot-blot analysis, allowed the evaluation of the approximate number of mRNA molecules expressed by single cells. IA permitted the evaluation of cultured cells' morphological parameters (such as cytoplasm and nucleus areas) modifications in relation to specific mRNAs expression, which can vary during cell cycle, development, aging, and in different pathologies and treatment with drugs. ISH-IA was applied for the evaluation of mRNA isoforms generated by alternative splicing in single cells. This methodology was also applied for the semiquantitative evaluation and comparison of mRNA levels expressed by different cell types in human normal and tumor tissue sections.

Alternative Splicing↗
PubMed1992

Study of fibronectin and mRNA in human laryngeal and ectocervical carcinomas by in situ hybridization and image analysis.

The expression of fibronectin (FN) mRNA was studied in histological sections of surgical biopsies from human laryngeal and ectocervical invasive carcinomas of different grading stages by in situ hybridization and image analysis. This approach made it possible to identify the cell types synthesizing FN mRNA in the tissue sections and to compare semi-quantitatively the FN mRNA levels expressed in the different specimens. The carcinoma cells synthesized low levels of FN mRNA, comparable to those detected in control epithelia and connective-tissue fibroblasts. Well-differentiated (G1) laryngeal and ectocervical carcinomas induced the synthesis of FN mRNA--to levels 7 to 13 times higher than in control connective tissues--in the stromal fibroblasts surrounding the tumors. In carcinoma samples analysed, the amount of FN mRNA detected in the stroma decreased in relation to tumor grading (from G1 to G3) and the stromal destruction. FN mRNA was not detectable in the endothelial cells of venules while it was present in large amounts in those surrounding the capillaries present in the stroma. These data indicate that FN, usually observed around carcinomas, is produced by stromal fibroblasts, which are induced to express FN mRNA, presumably in response to diffusible factors produced by the tumor cells, and/or by endothelial cells of the infiltrating capillary vessels. The induction of FN mRNA, inversely proportional to the tumor grading, may be useful in evaluating the invasion potential of the tumor.

DNA Probes↗
PubMed1992

Exclusion of stromelysin-1, stromelysin-2, interstitial collagenase and fibronectin genes as the mutant loci in a family with recessive epidermolysis bullosa dystrophica and a form of cerebellar ataxia.

The interstitial collagenase gene (CLG), one of the main candidates in severe generalized recessive epidermolysis bullosa dystrophica (SGREBD), is closely linked to the stromelysin-1 (STMY1) and stromelysin-2 (STMY2) genes. These three loci map on chromosome 11 (q21-q22.3), where they constitute a cluster of genes coding for metalloproteinases involved in the degradation of the extracellular matrix (ECM). A recessive form of cerebellar ataxia of post-puberal onset (CLA1) has also been assigned to chromosome 11 (q14-q21). Since useful restriction fragment length polymorphisms (RFLPs) for the CLG gene are not available, we have studied the inheritance of the marker TaqI RFLP of the STMY1 gene in a North Italian family with a child affected by SGREBD, and his two sisters showing cerebellar ataxia (CA) of post-puberal onset. We have also studied the MspI RFLP of the fibronectin gene (FN1), which is located on chromosome 2q34-q36, and which codes for non-collagenous matrix proteins. Since we did not observe the segregation of the pathological phenotypes with STMY1 and FN1 RFLPs, we excluded the involvement of these genes in both the SGREBD and CA present in this family. The exclusion of the STMY1 gene indicates that the mutation causing SGREBD cannot be located in the CLG and/or STMY2 genes because of their proximity to the STMY1 locus. These data also indicate that the CA form here reported is not attributable to alterations in regions close to the collagenase cluster on chromosome 11.

Blotting, Southern↗
PubMed1992

Histological human papillomavirus induced lesions: typization by molecular hybridization techniques.

The viral typization in Human Papillomavirus (HPV) infections of the lower female genital tract is relevant both from the epidemiological and the clinical point of view. We have tested DNA from specimens obtained by guided biopsies on neoplastic and benign lesions, using single probes of the different virus types (6, 11, 16 and 18) by Dot-blot and Southern blot analysis. According to previous studies HPV 16 and 18 have been detected in neoplastic lesions, while 6 and 11 were more frequently found associated to condylomata. Negative specimens and intermediate were 36% of the total. In our experience both methods have shown same sensibility.

Adenocarcinoma↗
PubMed1991

Thrombotic and hemorrhagic complications in essential thrombocythemia. A retrospective study of 103 patients.

A retrospective study of 103 patients with essential thrombocythemia was carried out to evaluate the incidence of thrombohemorrhagic complications and establish whether there were any correlations between these events and clinical or laboratory data. At onset or during the course of the disease, 26 patients (25.2%) presented thrombotic and 12 (11.6%) hemorrhagic complications: among the latter, six patients had gastrointestinal bleeding during antiaggregant therapy. No significant correlations were observed between thrombohemorrhagic complications and platelet count, age, sex, platelet function, bleeding time, or therapeutic regimen. However, there was a statistically significant correlation between a positive patient history for thrombotic events and an increase in thromboses. In agreement with other authors, it is believed that the best approach in asymptomatic patients is strict surveillance without treatment. Chemotherapy and/or treatment with antiaggregant agents should be reserved for symptomatic patients or patients with a positive history for thrombotic events.

Adolescent↗
PubMed1991

Phenotypic correction of the defective fibronectin extracellular matrix of Ehlers-Danlos syndrome fibroblasts.

In vitro cultured skin fibroblasts derived from Ehlers-Danlos Syndrome (EDS) type I to VIII patients lack fibronectin-containing extracellular matrix (FN-ECM) which can be restored when EDS cells are cocultivated over a feeder of control fibroblasts. Further analysis, focused on EDS types III and IV cells, showed that partial matrix correction in EDS type III cells can be obtained by their cultivation over a feeder of EDS type IV fibroblasts, but not vice versa. An apparently normal FN-ECM can be restored in EDS types III and IV cells also by the addition of cellular--but not plasma--FN. These biological features might be used for a better understanding of ECM assembly and for the characterization of the different EDS cell types.

Cells, Cultured↗