The length of telomeric G-rich strand 3'-overhang measured by oligonucleotide ligation assay.

A typical G-rich telomeric DNA strand, which runs 5'-->3' toward the chromosome ends, protrudes by several nucleotides in lower eukaryotes. In human chromosomes long G-rich 3'-overhangs have been found. Apart from the standard G-rich tail, several non-canonical terminal structures have been proposed. However, the mechanism of long-tail formation, the presence and the role of these structures in telomere maintenance or shortening are not completely understood. In a search for a simple method to accurately measure the 3'-overhang we have established a protocol based on the ligation of telomeric oligonucleotide hybridized to non-denatured DNA under stringent conditions (oligonucleotide ligation assay with telomeric repeat oligonucleotide). This method enabled us to detect a large proportion of G-rich single-stranded telomeric DNA that was as short as 24 nt. Nevertheless, we showed G-tails longer than 400 nt. In all tested cells the lengths ranging from 108 to 270 nt represented only 37% of the whole molecule population, while 56-62% were <90 nt. Our protocol provides a simple and sensitive method for measuring the length of naturally occurring unpaired repeated DNA.

Absence of association between a variant of the mast cell chymase gene and atopic dermatitis in an Italian population.

Atopic dermatitis (AD) is a chronic dermatitis which belongs to the group of atopy-related diseases together with asthma and rhinitis. IgE and mast cell chymase (MCC) play a key role in atopic or allergic inflammation of the skin. An association between AD and a genetic variant of the MCC has been reported in a Japanese population, but failure of confirmation has rendered this association questionable. We have tested for genetic association to an MCC variant in relation to AD in an Italian population. No significant association was found between AD and MCC genotypes. These data suggest that BstXI MCC polymorphism may not be involved in AD.

In situ detection of telomerase catalytic subunit mRNA in glioblastoma multiforme.

Activation of telomerase may allow unlimited cell proliferation and immortalization. One of the telomerase protein subunits has a reverse transcriptase (hTERT) activity that is essential for telomerase function and regulation. In human gliomas, telomerase is frequently associated with malignant tumor progression. In our study, we investigated the expression of hTERT at the cellular level in 34 primary de novo glioblastoma multiforme (GBM) by in situ hybridization (ISH). The expression of hTERT in tumor tissue was also assessed by RT-PCR. In addition, telomerase activity measured by telomeric repeat amplification protocol (TRAP) and telomere length polymorphism assayed by telomere restriction fragment (TRF) Southern blot were investigated. We found that all GBM, including those with negative TRAP reaction, contained abundant amounts of cytoplasmic hTERT mRNA. Interestingly, the ISH analysis revealed that the hTERT mRNA was homogeneously expressed by the whole tumor cell population in about 60% of the GBM. In the remaining cases, hTERT was absent in subsets of tumor cells. TRF analysis, which shows that both TRAP-positive and TRAP-negative de novo GBM have elongated telomeres, further supports that telomerase activity is present in all de novo GBM. Correlations with tumor size and extent of necrosis suggest that hTERT reactivation is an early event in GBM development and that telomerase activity may be lost in subpopulations of neoplastic cells during tumor progression. Finally, ISH analysis of hTERT mRNA seems to provide a prognostic parameter for primary de novo GBM.

Multiple genetic lesions in solid tumors: relevance to diagnosis, prognosis, and molecular mechanisms.

In recent years, significant progress has been made in identifying characteristic chromosomal and molecular rearrangements associated with several solid tumors. Most solid tumors studied have been found to be characterized by recurrent chromosomal abnormalities that are specific to histologic types. We have studied primary specimens of malignant melanoma, gastrointestinal cancer, renal carcinoma, lung and ovarian cancer, by cytogenetic and molecular means, and we discuss the genetic alterations found. Brief descriptions of the potential clinical utility, and biological relevance changes in these disorders are also discussed.

Cytogenetic, molecular and phenotypic characterization of the newly established renal carcinoma cell line KJ29. Evidence of translocations for chromosomes 1 and 3.

The established non papillary human renal carcinoma cell line (RCC) KJ29 was submitted to a multiparametric characterization to evaluate its potential use for in vitro and in vivo studies. The cell line grows in vitro as monolayer as well as cell suspension. Cytogenetic analysis has shown a modal chromosome number of 50 with some marker chromosomes, including rearrangements of chromosomes 1 and 3. The antigenic phenotype is characterized by co-expression of cytokeratin and vimentin, as well as expression of urothelium differentiation antigens, low levels of class II MHC antigens and no class I antigens. A differential expression of the VLA-3 integrin heterodimer has been detected between the adherent and non adherent cell population. The cell line which is highly tumorigenic in athymic mice displays expression of erb B-2 and c-met oncogenes and high expression of cell-cycle related and Ha-ras 1 genes.