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S Levanat

Publications and source records attributed to S Levanat.

At least 19 recordsLinked to original sources
PubMed2001

PTCH gene altered in dentigerous cysts.

Motivated by the evidence that odontogenic keratocysts are associated with genetic alterations, we examined the possibility that development of other odontogenic cysts can be attributed to gene malfunctioning, in particular to the PTCH gene. Cyst epithelium was examined for polymorphism on chromosome 9q22.3, the region that contains the PTCH gene. Loss of heterozygosity (LOH) for the D9S287 marker and/or D9S180 marker was observed in about 50% of dentigerous cysts, whereas radicular cysts gave no indication of lesions in the PTCH region. As a more direct argument for PTCH involvement in cystic growth, we report evidence of PTCH expression in dentigerous cyst lining, which indicates malfunctioning of the relevant signaling pathway. While we found no reason to believe that PTCH should be associated with radicular cysts, other genes may be implicated in their development. We performed immunohistochemical comparisons of keratocysts, dentigerous and radicular cysts for the nonmetastatic marker Nm23. A graded response placed radicular cysts in between the other two types, suggesting a similar neoplastic character for their epithelial proliferation.

Adolescent↗
PubMed2001

Aberration of FHIT gene is associated with increased tumor proliferation and decreased apoptosis-clinical evidence in lung and head and neck carcinomas.

BACKGROUND: Human FHIT (fragile histidine triad) gene is highly conserved gene homologous to a group of genes identified in prokaryotes and eukaryotes. Loss of FHIT function may be important in the development and/or progression of various types of cancer. MATERIALS AND METHODS: We undertook a clinical study to analyze the relation between aberrant function of FHIT gene, tumor cell proliferation, and intensity of apoptosis as well as prognostic output in lung and squamous cell head and neck carcinoma (HNSCC). Status of FHIT gene, expression of p21waf1, intensity of apoptosis, and cell proliferation were analyzed in HNSCC and lung carcinoma tissues by molecular genetic methods, immunohistochemistry, [3H]-thymidine labeling method, and FACScan analysis in frozen and paraffin-embedded tissue sections. RESULTS: The majority of the malignant lung and HNSCC lesions displayed aberrant expression of FHIT gene, followed by low or negative expression of p21waf1, and increased intensity of cell proliferation. Similar results were obtained on synchronous combinations of normal, precancerous, and cancerous head and neck tissues. The observed changes increased with progression of these lesions. We examined tumor and corresponding normal tissue samples for microsatellite markers D3S1300 and D3S4103 to evaluate the loss of heterozygosity (LOH) at the FHIT gene loci. We found high percentage of LOH in both lung tumors and HNSCC (75% for D3S1300 and 79% for D3S4103 in lung cancer, and 87% for D3S1300 and 78% for D3S4103 in HNSCC). The median survival time of the patients suffering from lung cancer without FHIT protein expression was 22.46 months and that of the patients with FHIT expression 36.04 months. FHIT-negative cases tended to correlate with a worse prognosis, but this was not statistically significant. Median survival time of HNSCC patients without FHIT protein expression was 30.86 months and that of the patients with FHIT expression was 64.04 months (p < 0.05). CONCLUSIONS: Our results show a correlation between aberrant FHIT expression, a low rate of apoptosis, and high tumor cell proliferation. Aberrant FHIT gene could be a prognostic marker in lung cancer.

Acid Anhydride Hydrolases↗
PubMed2000

Involvement of PTCH gene in various noninflammatory cysts.

Constitutional hemizygous inactivation of PTCH, the Shh signaling pathway gene that moderates the signal, manifests itself as nevoid basal cell carcinoma syndrome or Gorlin syndrome, a condition variably characterized by a number of developmental disorders and malformations, and by predisposition to some malignancies, basal cell carcinoma in particular. Loss of heterozygosity for the PTCH region was found several years ago in the epithelial lining of odontogenic keratocysts, the cyst type with highly increased incidence in nevoid basal cell carcinoma syndrome. This finding confirmed the expectations that the gene responsible for the syndrome would have a decisive role in the genesis of these cysts even when they are not syndrome related. Suggestive temporal distribution of Shh signaling, recently observed during tooth development, lead us to investigate PTCH association with dentigerous cysts, the other major noninflammatory cyst of odontogenic origin. We report here that PTCH appears to be inactivated in dentigerous cysts, suggesting that it is responsible for their genesis as well. More generally, if our similar observations of incomplete heterozygosity in this region for dermoid cysts can be interpreted as loss of heterozygosity, PTCH alterations may prove to be a necessary, and perhaps the initiating event, in formation and growth of various noninflammatory cysts. This would be consistent with our view that local PTCH inactivation can, under favorable circumstances, lead to persistent though not by itself truly aggressive cell proliferation.

Adolescent↗
PubMed2000

Variable expression of Gorlin syndrome may reflect complexity of the signalling pathway.

Nevoid Basal Cell Carcinoma Syndrome (NBCCS) or Gorlin syndrome is an autosomal dominant disorder characterized by cancer predisposition and multiple developmental defects. Syndrome related disorders have been attributed to alterations of PTCH gene, which plays an important role in Shh signalling pathway. Unresolved complexities of the pathway impede understanding of mechanisms through which PTCH alterations lead to variable phenotype expression in Gorlin syndrome patients, while the role of chromosomal instability is not yet clear. To increase our understanding of NBCCS, every manifestation of the syndrome and associated genetic damage should be seriously considered. Therefore, several atypical NBCCS cases are presented in this paper.

Adult↗
PubMed1999

Involvement of patched (PTCH) gene in Gorlin syndrome and related disorders: three family cases.

AIM: To find genetic alterations in PTC or other genes of the Shh/PTCH pathway in tumorous and non- tumorous samples from three families and to correlate them with the varying expression of disorders in presented nevoid basal cell carcinoma syndrome (NBCCS) phenotypes. METHOD: DNA was extracted from archival paraffin-embedded tissues, tumor tissue or peripheral blood leukocytes, and the loss of heterozygosity (LOH) and single strand conformational polymorphism analysis was performed using PCR with primers for polymorphic 9q22.3 markers (D9S196, D9S287, D9S180, D9S127); PTCH exons 3, 6, 8, 13, 15, 16; and smo (smoothened) exon 1. G-banding tecnique was used for cytogenetic analysis of the peripheral blood lymphocytes. RESULTS: We found a LOH for PTCH in several cases and variability in smo in one case. In one case NBCCS could reasonably be ascribed to hemizygous PTCH inactivation, while in other two families this typical correlation between the syndrome phenotype and the observed genetic alterations could not been established. CONCLUSIONS: Further analysis of relatively sparse cases of NBCCS is needed before the symptoms of the syndrome could be convincingly explained by genetic alterations in the Shh/PTCH signalling pathway.

Adolescent↗
PubMed1997

Pulsed-field gel electrophoresis and FISH mapping of chromosome 9q22: placement of a novel zinc finger gene within the NBCCS and ESS1 region.

Chromosome 9q22 is a gene-rich region to which several human disease loci have been mapped. Pulsed field gel electrophoresis (PFGE) and FISH were used to determine the order of and distance between 12 chromosome 9q22 markers flanked by D9S196 and D9S180. D9S780 and XPA were within 190 kb of each other and hybridized to the same 460-kb NotI fragment as D9S180. ZNF169, a novel kruppel-type gene, and D9S280 shared several PFGE fragments indicating that they are not more than 300 kb apart. Interphase FISH showed that COL15A1 lies distal to the region bounded by D9S180 and D9S196 and that ZNF169 is adjacent to D9S196. Based on the restriction fragment lengths in this region and estimates from FISH, the distance from D9S180 to D9S196 is not less than 2 Mb.

Basal Cell Nevus Syndrome↗
PubMed1996

Molecular analysis of chromosome 9q deletions in two Gorlin syndrome patients.

Gorlin syndrome is an autosomal dominant disorder characterized by multiple basal cell carcinomas, medulloblastomas, ovarian fibromas, and a variety of developmental defects. All affected individuals share certain key features, but there is significant phenotypic variability within and among kindreds with respect to malformations. The gene (NBCCS) maps to chromosome 9q22, and allelic loss at this location is common in tumors from Gorlin syndrome patients. Two recessive cancer-predisposition syndromes, xeroderma pigmentosum group A (XPAC) and Fanconi anemia group C (FACC), map to the NBCCS region; and unusual, dominant mutations in these genes have been proposed as the cause of Gorlin syndrome. This study presents cytogenetic and molecular characterization of germ-line deletions in one patient with a chromosome 9q22 deletion and in a second patient with a deletion of 9q22-q3l. Both have typical features of Gorlin syndrome plus additional findings, including mental retardation, conductive hearing loss, and failure to thrive. That Gorlin syndrome can be caused by null mutations (deletions) rather than by activating mutations has several implications. First, in conjunction with previous analyses of allelic loss in tumors, this study provides evidence that associated neoplasms arise with homozygous inactivation of the gene. In addition, dominant mutations of the XPAC and FACC1 genes can be ruled out as the cause of Gorlin syndrome, since the two patients described have null mutations. Finally, phenotypic features that show variable expression must be influenced by genetic background, epigenetic effects, somatic mutations, or environmental factors, since these two patients with identical alterations (deletions) of the Gorlin syndrome gene have somewhat different manifestations of Gorlin syndrome.

Adolescent↗
PubMed1993

Mitogenicity of the earthworm's (Eisenia foetida) insulin-like proteins.

1. Biologically active glycolipoprotein complex (G-90), isolated from whole earthworm tissue extract (Eisenia foetida), was separated into seven fractions by gel-filtration. 2. It has been shown by radioimmunoassay that each of the fractions, except the lightest one, is cross-reactive with porcine anti-insulin antibodies. Molecules that possess such activity were detected by immunoblotting. 3. All fractions, except the heaviest and the lightest one, stimulate mammalian normal and transformed cell proliferation in serum-free conditions in vitro. The intensity of stimulation depends on cell type. Stimulation is completely abolished if the medium is supplemented with fetal calf serum.

Animals↗
PubMed1992

A new source of biologically active compounds--earthworm tissue (Eisenia foetida, Lumbricus rubelus).

1. Earthworms possess immunological recognition and memory as well as high regenerative abilities. Coelomic fluid was used as a source of biologically active compounds. 2. A biologically active glycolipoprotein extract from a whole earthworm tissue homogenate was isolated and named G-90. 3. G-90 forms precipitation arcs in gel with different animal and human sera. 4. It alters murine cell growth rate in vitro in serum in a dose-dependent manner and slows murine tumor growth in vivo. 5. G-90 does not contain mutagens or carcinogens.

Animals↗
PubMed1991

The role of insulin-related substance in Hodgkin's disease.

An insulin-related growth-promoting substance was detected in the serum of a patient with Hodgkin's disease who suffered from severe hypoglycaemia, as well as in the supernatant of homogenized spleen tissue of the same patient. Low concentrations of this substance enhanced DNA synthesis of short-term-cultured spleen tumour cells obtained from the same patient, while the addition of anti-insulin antiserum interfered with that effect. Moreover, the preincubation of this insulin-related substance with the anti-insulin antiserum abrogated its stimulatory effect on tumour cell proliferation. Both insulin and the insulin-related substance bound to patients splenocytes to a similar extent. The data suggest that the insulin-related substance, found in this particular case of Hodgkin's disease, plays a role in tumour progression by an autocrine mechanism.

Blood Glucose↗
PubMed1991

Collagenase derived from human fibrosarcoma is responsible for degradation of basement membranes.

A collagenase-like enzyme with the ability to degrade the proteins of artificial basement membranes (BM) was isolated from human fibrosarcoma. Secretion of the same peptide was observed from the primary fibrosarcoma cell cultures. This peptide degrades the artificial basement membranes derived from bovine corneal endothelial cells. Using electrophoretic methods it was found that the isolated and partially purified enzyme consists of eight bands of different molecular mass corresponding to the collagenase standard from Cl. histolyticum. Only two bands with molecular masses of 22,000 (pI 5.5) and 63,000 (pI 5.9) degrade BM.

Animals↗
PubMed1990

Substance immunologically cross-reactive with insulin from murine myeloid leukemia: purification and characterization.

A substance immunologically cross-reactive with insulin (SICRI) appears in murine myeloid leukemia. Progression of disease is paralleled by the increase of SICRI levels in the serum; this increase of SICRI levels did not correlate with a decreased concentration of circulating glucose. SICRI was isolated and purified from spleen infiltrated with leukemic cells. Monospecific antiinsulin immunoglobulin G was used for immunoaffinity chromatography to isolate SICRI from tumor tissue. The purified substance yielded a single band with a molecular mass of about 150 kDa in polyacrylamide gel electrophoresis under denaturating and non-denaturating conditions. Purified SICRI enhanced growth of myeloid leukemia cells in soft agar. Biochemical and biological data together with our previous results obtained in other experimental tumors provide evidence that SICRI and insulin are two distinct biologically active agents. SICRI plays a role in murine myeloid leukemia as an autocrine growth promoting factor.

Animals↗
PubMed1990

Protective role of transforming growth factor beta (TGF beta) in tumor-induced degradation of basement membranes.

Human fibrosarcoma cells derived from a patient with multiple metastases extensively degrade artificial basement membranes (BM) and secrete interstitial type of collagenase, a proteolytic enzyme responsible for degradation of type I collagen. Exposure of invasive cell line to TGF beta abrogates destruction of BM.TGF beta reduces collagenase activity and stimulates specific metalloproteinase inhibitor (TIMP) in invasive tumor cells. We preassume that TGF beta could play a protective role in tumor invasion.

Basement Membrane↗
PubMed1989

Growth factors in human tumors.

Various human tumor tissues contain different growth factors. In some cases progression of tumors is paralleled by elevated levels of these substances in blood or in tumor tissue. There is evidence that these growth promoting peptides might stimulate tumor growth. The growth of most tumors was associated with insulin-like substances (MW 45,000). We isolated and purified a substance immunologically cross-reactive with insulin (SICRI) from human melanoma. We found the molecular weight of affinity purified SICRI to be approximately 120,000. Our in vitro experiments with human renal carcinoma cells and growth factors suggest an important role of these molecules in tumor progression.

Cell Division↗
PubMed1989

Isolation and purification of a substance immunologically cross-reactive with insulin (SICRI) from tumor tissue.

1. A substance immunologically cross-reactive with insulin (SICRI) was isolated and purified from murine melanoma B16 and myeloid leukemia. 2. Monospecific anti-insulin immunoglobulin G was coupled with CNBr-activated Sepharose 4B to yield an adsorbent. The immunoaffinity column was used to isolate SICRI from tumor tissue. 3. Purified SICRI yielded a single band with mol. wt 158,000 on SDS-PAGE. After non-denaturing conditions SICRI appeared again in one single peak. 4. Affinity purified SICRI was shown to be a potent growth factor for different human and murine transformed and normal cells. 5. Biochemical and biological data provide evidence that SICRI and insulin are two distinct biologically active agents.

Animals↗
PubMed1989

Substance immunologically cross-reactive with insulin (SICRI) stimulates cell division.

A substance immunologically cross-reactive with insulin (SICRI) was isolated and purified from murine melanoma B16. Biochemical and biological data provide evidence that SICRI and insulin are two distinct biologically active agents. In vitro, SICRI has stimulated the DNA and protein synthesis, cell growth or colony-forming ability of 19 normal and transformed cell lines of human and rodent origin. It indicates that SICRI is a potent nonspecific growth factor. The most pronounced stimulatory effect of SICRI on proliferative capacity of cells is observed with cells at G0/G1 point of the cell cycle.

Animals↗