Biomedical subjects

Salwa Sheikh

Publications and source records attributed to Salwa Sheikh.

4 recordsLinked to original sources

PubMed2006

High throughput tissue microarray analysis of FHIT expression in diffuse large cell B-cell lymphoma from Saudi Arabia.

Recent studies have suggested a potential prognostic role of alterations of the fragile histidine triad (FHIT) gene in diffuse large B-cell lymphoma. To evaluate possible mechanisms of FHIT inactivation and to further clarify its potential prognostic relevance, we analyzed a set of 114 diffuse large B-cell lymphoma with clinical follow-up information. Tissue microarrays were analyzed by immunohistochemistry for protein expression, and corresponding DNA samples were analyzed for FHIT promotor hypermethlyation. Reduced or absent FHIT expression was found in 75 of 114 diffuse large B-cell lymphoma (66%), but was unrelated to clinical tumor stage or patient prognosis. FHIT promotor hypermethylation was observed in 29 of 93 (23%) interpretable diffuse large B-cell lymphoma. Hypermethylation was not significantly correlated to protein expression loss, which could be explained by competing mechanisms for FHIT inactivation in a substantial fraction of non FHIT hypermethylated diffuse large B-cell lymphoma. Hypermethylation was significantly associated with poor prognosis of diffuse large B-cell lymphoma patients and predominantly seen in nongerminal center diffuse large B-cell lymphoma (27%), but less frequent (13%) in germinal center diffuse large B-cell lymphoma. In summary, these data suggest that promotor hypermethylation is responsible for reduced FHIT expression in a substantial subset of diffuse large B-cell lymphoma, which is primarily composed of nongerminal center subtype with poor patient prognosis.

Acid Anhydride Hydrolases↗

PubMed2006

High epidermal growth factor receptor amplification rate but low mutation frequency in Middle East lung cancer population.

Epidermal growth factor receptor (EGFR) exon 18-21 mutations were shown to be highly predictive of response to gefitinib (Iressa) therapy in lung cancer. Studies on Western and Japanese lung cancers have indicated substantial differences in the EGFR mutation frequency between these populations. To investigate the prevalence of EGFR in another distinct ethnic group, EGFR alterations were studied in 47 consecutive non small cell lung cancers from Saudi Arabia by immunohistochemistry, fluorescence in situ hybridization, and DNA sequencing. Detectable EGFR expression was seen in 69.8% of 43 interpretable cancers. Epidermal growth factor receptor amplification, present in 15.3% of 39 analyzable cancers, was strongly associated with high levels of EGFR expression (P = .0047). Only 1 exon 18-21 mutation was seen among 34 lung cancers that could be successfully sequenced. It is concluded that EGFR exon 18-21 mutations are rare in Middle East patients with lung cancer and occur in a similar range as in Western patients. The remarkable high rate of EGFR gene amplifications could potentially facilitate studies on the predictive role of gene copy number changes for response to anti-EGFR therapies in Middle East patient sets.

Adenocarcinoma↗

PubMed2006

Overexpression of claudin proteins in esophageal adenocarcinoma and its precursor lesions.

Claudins are components of tight junctions important in intercellular barriers and cell polarity. The authors identified upregulation of Claudins 3, 4, and 7 in gastric adenocarcinoma using Affymetrix U-133 oligonucleotide microarrays and immunohistochemistry (IHC). While normal gastric mucosa lacked Claudin 3, 4, and 7 expression, intestinal metaplasia and dysplasia showed these proteins. The authors hypothesized that Claudins would be similarly overexpressed in Barrett's esophagus (BE)/adenocarcinoma. Claudins 3, 4, and 7 gene expression was analyzed by Affymetrix U-133 microarrays in three esophageal adenocarcinomas, one case of BE, and three normal esophagi. IHC validation was performed using tissue microarrays constructed from esophageal resection specimens containing squamous (44 cases), gastric (40 cases), and non-dysplastic BE (16 cases), low-grade and high-grade dysplasia (16 and 26 cases), adenocarcinoma (58 cases), and nodal metastases (27 cases). IHC staining was scored semiquantitatively (0+ to 4+). By microarray analysis, Claudin 3 showed a marked increase in mRNA expression compared with normal esophagus (approximately 100-fold). Claudins 4 and 7 were modestly increased (2.2- and 1.3-fold). By IHC, Claudin 3 expression was 1+ in most (>95%) normal squamous or gastric tissues and 2+ to 4+ in more than 80% of high-grade dysplasia, adenocarcinoma, and metastases specimens. Claudin 4 protein expression was 2+ or less in most squamous and gastric mucosa (>90%) but 3+ or 4+ in BE, low- and high-grade dysplasia, adenocarcinoma, and metastases specimens (>90%). Claudin 7 expression was minimal in squamous and gastric mucosa but strong (3+ to 4+) in BE and low-grade dysplasia. In high-grade dysplasia, adenocarcinoma, and metastases, Claudin 7 was less intense, with 60% to 70% staining 3+ or 4+ and 30% to 40% staining weakly (1+ or 2+). The findings suggest that alterations in Claudin proteins are an early event in tumorigenesis and may provide targets for diagnosis and directed therapy for esophageal adenocarcinoma and its precursors.

Adenocarcinoma↗

PubMed2005

Predominance of high-grade pathway in breast cancer development of Middle East women.

Recent data have suggested considerable molecular differences in cancers from various ethnical groups. As molecular features are increasingly used for predicting cancer prognosis and response to therapy, better knowledge of ethnic molecular features is important. To identify potential molecular differences between breast cancers in Europe and the Middle East, we analyzed consecutive breast cancer series from Switzerland (n=2197) and Saudi Arabia (n=204). Tissue microarrays were analyzed by fluorescence in situ hybridization for HER2, CCND1, MYC, and EGFR amplification. The data revealed marked differences between Saudi and Swiss patients. Saudi breast cancers had a markedly higher frequency of HER2 (31 vs 17%; P<0.0001) and MYC (16 vs 5%; P<0.0001) amplifications than Swiss breast cancers. Remarkably, this was partly due to a much higher incidence of grade 3 cancers in the Saudi than in the Swiss population (65 vs 32%; P<0.0001). However, differences in amplification frequency hold also true within grade 3 cancers (HER2: 40 vs 30%, P<0.05; MYC: 22 vs 11%, P=0.002). Interestingly, in combination with known age standardized incidence rates of breast cancer in Saudi Arabia (21.6/100 000) and Switzerland (70.1/100 000), these data suggest that the incidence of high-grade breast cancer is comparable for Saudi and Swiss women, while the incidence of low-grade breast cancers is about 14 times lower in Saudi than for Swiss women. These observations suggest that a difference in genetic susceptibility and/or lifestyle between Saudi and Swiss women has a substantial and much higher than expected impact on the risk of low-grade breast cancer.

Adult↗