Disparate E-cadherin mutations in LCIS and associated invasive breast carcinomas.

AIMS: The relation between lobular carcinoma in situ (LCIS) and invasive breast cancer is unresolved. In an attempt to establish whether LCIS is a precursor of invasive cancer the mutational status and the expression of E-cadherin was analysed in LCIS and associated invasive breast carcinoma in 23 patients. METHODS: Foci of LCIS and associated invasive carcinoma were individually microdissected from tissue from 23 patients. Exons 4-16 of the E-cadherin gene were analysed using single strand conformation polymorphism (SSCP); protein expression and the localisation of E-cadherin and beta-catenin were assessed with the use of immunohistochemistry. RESULTS: Immunohistochemistry revealed a lack of expression of E-cadherin and beta-catenin in most LCIS samples and invasive foci. In all but four cases, the staining pattern was identical in the LCIS and associated invasive areas. When E-cadherin was absent, beta-catenin was also undetected, suggesting a lack of expression of alternative classic cadherin members in these lesions. Coincident E-cadherin mutations in LCIS and associated invasive carcinoma were not identified in this series of patients. However, mutational analysis of E-cadherin in multiple foci of carcinoma in situ surrounding an invasive lesion provided evidence to support ductal carcinoma in situ as a precursor of invasive ductal carcinoma. CONCLUSION: These data support the hypothesis that LCIS is not a precursor of invasive breast carcinoma but a marker of increased risk of developing invasive disease.

Molecular analysis of PTEN and MXI1 in primary bladder carcinoma.

Loss of heterozygosity (LOH) on 10q is associated with late-stage events in urothelial neoplastic progression. The tumor suppressor gene PTEN, which is mutated or homozygously deleted in numerous cancers, maps to a region of 10q within the reported region of minimal loss in bladder tumors. In two recent studies alterations in the PTEN gene occur at a low frequency in bladder tumors displaying 10q LOH. We have screened 35 late-stage bladder tumors for mutations in PTEN and MXI1, both genes mapping to chromosome 10q. Using single-strand conformation polymorphism analysis, we identified 6 tumors harboring mutations in PTEN and 2 additional tumors displaying homozygous deletion at this locus. No MXI1 mutations were identified within the same tumor panel. Of 16 bladder tumor cell lines analyzed, 2 showed homozygous deletion of PTEN and 3 harbored point mutations resulting in an amino acid change. Two cell lines harbored missense mutations in MXI1. We report a significantly higher frequency of PTEN alterations in bladder carcinoma (23%) than was previously recorded, with no accompanying mutations in the MXI1 gene.

Somatic mutation of PTEN in vulvar cancer.

PTEN, a candidate tumor suppressor gene located at chromosome 10q23.3, has been shown to be mutated in approximately 40% of endometrial cancers. Such mutations have also been identified in endometrial hyperplasia, indicating that inactivation of the PTEN tumor suppressor gene is an early event in the genesis of some endometrial cancers. In this study, we have extended the analysis of PTEN in gynecological cancer to include adenocarcinoma of the cervix and vulvar carcinomas. Microdissected tissue (including normal tissues), preneoplastic, and neoplastic lesions were analyzed from 9 patients with cervical cancer and 10 patients with vulvar cancer. Only 1 cervical adenocarcinoma displayed a PTEN mutation. In contrast, five of eight vulvar carcinomas studied harbored PTEN mutations. Alterations were identified in carcinoma in situ as well as squamous cell carcinoma of the vulva. In two patients, PTEN mutations were identified in mucosal regions with mild or focal dysplasia. These results suggest that PTEN is frequently altered in vulvar carcinomas and can be found associated with early dysplastic changes in vulvar mucosa.

Inhibition of HIV-1 replication by combination of a novel inhibitor of TNF-alpha with AZT.

The small molecule S9a was derived from an established tumor necrosis factor-alpha (TNF-alpha) inhibitor (Canventol) by replacement of the isopropylidine group with a phenyl ring. S9a at 10 to 100 nM inhibited HIV production as potently as 3'-azido-3'-deoxythymidine (AZT), an inhibitor of viral reverse transcriptase. Furthermore, S9a and AZT in combination, at noncytoxic concentrations strongly inhibited HIV-1 replication that was more than additive and substantially prolonged the appearance of virus both in acutely infected CD4+ lymphocytes (SupT) in culture and in peripheral blood mononuclear cells (PBMCs) infected with a primary HIV-1 isolate. S9a inhibited TNF-alpha promoter-driven reporter gene activity. It was proposed that the mechanism of antiviral action of S9a was on the host cell, by blocking TNF-alpha transcription via a Tat-induced tar-independent loop, which decreases downstream NF-kappaB activation of HIV-1 long terminal repeat (LTR). S9a was superior to the first generation compound Canventol, which was superior to the natural compound sarcophytol A, demonstrating that further structure-based enhancement of potency of these compounds is feasible. This study suggests a therapeutic approach against AIDS by application of two drugs, one against a cellular and the other a viral target, which may provide an approach to the problem of frequent emergence of resistant variants to combinations of drugs that target only HIV genes.