Mohamed A. Shawarby

Protein expression profile and prevalence pattern of the molecular classes of breast cancer - a Saudi population based study

BackgroundBreast cancer is not a single entity but a diverse group of entities. Advances in gene expression profiling and immunohistochemistry as its surrogate marker have led to the unmasking of new breast cancer molecular subtypes, resulting in the emergence of more elaborate classification systems that are therapeutically and prognostically more predictive. Molecular class distribution across various ethnic groups may also reveal variations that can lead to different clinical outcomes in different populations.MethodsWe aimed to analyze the spectrum of molecular subtypes present in the Saudi population. ER, PR, HER2, EGFR and CK5/6 were used as surrogate markers for gene expression profiling to classify 231 breast cancer specimens. Correlation of each molecular class with Ki-67 proliferation index, p53 mutation status, histologic type and grade of the tumor was also carried out.ResultsOut of 231 cases 9 (3.9%) were classified as luminal A (strong ER +ve, PR +ve or -ve), 37 (16%) as luminal B (weak to moderate ER +ve, and/or PR +ve), 40 (17.3%) as HER2+ (strong or moderately positive HER 2 with confirmation by silver enhanced in-situ hybridization) and 23 (10%) as basal (CK5/6 or EGFR +ve). Co-positivity of different markers in varied patterns was seen in 23 (10%) of cases which were grouped into a hybrid category comprising luminal B-HER2, HER2-basal and luminal-basal hybrids. Ninety nine (42.8%) of the tumors were negative for all five immunohistochemical markers and were labelled as unclassified (penta negative). A high Ki-67 proliferation index was seen in basal (p = 0.007) followed by HER2+ class. Overexpression of p53 was predominantly seen in HER2 + (p = 0.001) followed by the basal group of tumors. A strong correlation was noted between invasive lobular carcinoma and hormone receptor expression with 8 out of 9 lobular carcinoma cases (88.9%) classifiable as luminal cancers. Otherwise, there was no association between the molecular class and the histologic type or grade of the tumor.ConclusionsSubtyping by use of this immunohistochemical panel revealed a prevalence pattern that is unique to our population; luminal tumors comprised only 19.9%, and the unclassified group (penta negative) 42.8%, a distribution which is distinctive to our population and in contrast with all Western studies. The presence of a predominant unclassified group also suggests that the currently used molecular analytic spectrum may not completely encompass all molecular classes and there is a need to further refine and develop the existing classification systems.

Histological Changes in Kidney and Liver of Rats Due to Gold (III) Compound [Au(en)Cl2]Cl

Introduction Development of novel metallodrugs with enhanced anti-proliferative potential and reduced toxicity has become the prime focus of the evolving medicinal chemistry. In this regards, gold (III) complexes with various ligands are being extensively investigated. In the current study renal and hepatic toxicity of a newly developed gold (III) compound [Au(en)Cl2]Cl was assessed by histopathological evaluation of liver and kidney specimens of rats exposed to the compound. Methods Male rats (n = 42) weighing 200–250 gram were injected single, varying doses of gold (III) compound [(dichlorido(ethylenediamine)aurate((III)]chloride [Au(en)Cl2]Cl in the acute toxicity component of the study. In the sub-acute toxicity part, a dose of 32.2 mg/kg (equivalent to 1/10 of LD50) was administered intraperitoneally for 14 consecutive days before sacrificing the animals. After autopsy, the renal and hepatic tissues were preserved in buffered formalin. Processing of the samples was followed by histopathological evaluation. The results were compared with the normal controls (n = 11). Results A dose of 32.2 mg/kg (1/10 of LD50) revealed no renal tubular necrosis. The predominant histopathological finding was mild pyelitis, a prominence of eosinophils and mild congestion. The hepatic lesions comprised varying extents of ballooning degeneration with accompanying congestion and focal portal inflammation. Conclusion Gold (III) compound [Au(en)Cl2]Cl causes minimal histological changes in kidney and liver of rats, reflecting its relative safety as compared to other clinically established antineoplastic drugs.

Very low prevalence of epidermal growth factor receptor (EGFR) protein expression and gene amplification in Saudi breast cancer patients

BackgroundBreast cancers which demonstrate EGFR protein expression, gene amplification and/or gene mutations may benefit therapeutically from tyrosine kinase inhibitors. In Western studies, EGFR protein expression has been demonstrated in 7-36% of breast cancer patients, while gene amplification has been found in around 6% of cases and mutations were either absent or extremely rare. Studies addressing EGFR protein expression and gene amplification in Saudi breast cancer patients are extremely scanty and the results reported have been mostly non-conclusive. Herein we report the prevalence of EGFR protein expression and gene amplification in a cohort of Saudi breast cancer patients.FindingsWe noticed a remarkably low incidence of EGFR protein expression (1.3%) while analyzing the spectrum of molecular subtypes of breast cancer in a Saudi population by immunohistochemistry. Also, EGFR gene amplification could not be demonstrated in any of 231 cases studied using silver enhanced in situ hybridization.ConclusionsThe extremely low incidence of EGFR protein expression and gene amplification in Saudi breast cancer patients as compared to Western populations is most probably ethnically related as supported by our previous finding in the same cohort of a spectrum of molecular breast cancer types that is unique to the Saudi population and in stark contrast with Western and other regionally based studies. Further support to this view is provided by earlier studies from Saudi Arabia that have similarly shown variability in molecular breast cancer subtype distribution between Saudi and Caucasian populations as well as a predominance of the high-grade pathway in breast cancer development in Middle East women. More studies on EGFR in breast cancer are needed from different regions of Saudi Arabia before our assumption can be confirmed, however.Virtual SlidesThe virtual slide(s) for this article can be found here: http://www.diagnosticpathology.diagnomx.eu/vs/1171467253537062.

Novel KRAS Gene Mutations in Sporadic Colorectal Cancer

Introduction In this article, we report 7 novel KRAS gene mutations discovered while retrospectively studying the prevalence and pattern of KRAS mutations in cancerous tissue obtained from 56 Saudi sporadic colorectal cancer patients from the Eastern Province. Methods Genomic DNA was extracted from formalin-fixed, paraffin-embedded cancerous and noncancerous colorectal tissues. Successful and specific PCR products were then bi-directionally sequenced to detect exon 4 mutations while Mutector II Detection Kits were used for identifying mutations in codons 12, 13 and 61. The functional impact of the novel mutations was assessed using bioinformatics tools and molecular modeling. Results KRAS gene mutations were detected in the cancer tissue of 24 cases (42.85%). Of these, 11 had exon 4 mutations (19.64%). They harbored 8 different mutations all of which except two altered the KRAS protein amino acid sequence and all except one were novel as revealed by COSMIC database. The detected novel mutations were found to be somatic. One mutation is predicted to be benign. The remaining mutations are predicted to cause substantial changes in the protein structure. Of these, the Q150X nonsense mutation is the second truncating mutation to be reported in colorectal cancer in the literature. Conclusions Our discovery of novel exon 4 KRAS mutations that are, so far, unique to Saudi colorectal cancer patients may be attributed to environmental factors and/or racial/ethnic variations due to genetic differences. Alternatively, it may be related to paucity of clinical studies on mutations other than those in codons 12, 13, 61 and 146. Further KRAS testing on a large number of patients of various ethnicities, particularly beyond the most common hotspot alleles in exons 2 and 3 is needed to assess the prevalence and explore the exact prognostic and predictive significance of the discovered novel mutations as well as their possible role in colorectal carcinogenesis.

Molecular classification of breast cancer: An overview with emphasis on ethnic variations and future perspectives

Morphologically identical breast cancers can display divergent clinical outcomes and responses to therapy. This can predominantly be attributed to molecular class differences that exist amongst histologically similar cancer types. Consequently, molecular classification can be more powerful than histopathology as a predictive factor for the different treatments. This article reviews the molecular classification of breast cancer and emphasizes that ethnic variations may exist in molecular class prevalence patterns. It also highlights key insights into the currently defined molecular classes as provided by ongoing research on primary breast cancers using recent state-of-the-art technology. Such research is revealing that significant molecular heterogeneity may exist within the molecular classes themselves. More diverse ethnic variations may also be unraveled. The results of ongoing and upcoming research may provide more precise prognostic and predictive information about breast cancer and perhaps a breakthrough step toward personaliziation of breast cancer treatment. Forty-one relevant articles (2000-2012) extracted through PubMed and Google advanced searches and at our institutes library were utilized to prepare the article, along with results of published and ongoing research by the authors.

Novel KRAS gene mutations in Saudi colorectal cancer patients

&NA; We report 7 novel KRAS gene mutations discovered while retrospectively studying the prevalence and pattern of KRAS mutations in cancerous tissue obtained from 56 Saudi colorectal cancer patients from the Eastern Province. Methods: Genomic DNA was extracted from paraffin-embedded, formalin-fixed cancerous and noncancerous colorectal tissues. A nested PCR approach was implemented. Successful and specific PCR products were then bi-directionally sequenced. The functional impact of the novel mutations on the K-ras protein was assessed using bioinformatics tools and molecular modeling. Results: KRAS gene mutations were detected in the cancer tissue of 24 out of 56 cases studied. Of these, 11 were in exon 4 (19.64%). The 11 cases with exon 4 aberrations harbored 8 different mutations. All of these except two altered the K-ras protein amino acid sequence and all except one were novel as revealed by COSMIC database. The detected novel mutations were found to be somatic. The molecular modeling data fit with the prediction from Polyphen-2 (polymorphism phenotyping v2) and SIFT (sorting intolerant from tolerant tools), as well as conservation data. One mutation is predicted to be benign and modeling also showed little predicted effect on protein structure. The remaining mutations are predicted to cause substantial changes in the protein structure in line with the predicted damaging effect by polyphen-2 software. Of these, the Q150X nonsense mutation is the second truncating mutation to be reported in colorectal cancer in the literature.1 Conclusions: Our discovery of novel exon 4 KRAS mutations that are, so far, unique to Saudi patients from the Eastern Province may be attributed to environmental factors and/or racial/ethnic variations due to genetic differences. Alternatively, it may be related to the paucity of clinical studies on mutations other than those in codons 12, 13, 61 and 146. Further KRAS testing on a large number of patients, particularly beyond the most common hotspot alleles in exons 2 and 3, is needed to assess the prevalence and explore the exact prognostic and predictive significance of the discovered novel mutations as well as their possible role in colorectal carcinogenesis. ReferencePalmirotta R, Savonarola A, Formica V, et al. A novel K-ras mutation in colorectal cancer. A case report and literature review. Anticancer Res 2009; 29: 3369–74.

Indeterminate cell tumor (Histiocytosis)

Indeterminate cell tumor (ICT; histiocytosis) is a rare disorder characterized by accumulation of histiocytes that do not fulfill the phenotypic criteria designated for Langerhans cells (LC). The cells classified as indeterminate exhibit overlapping features between dendritic cells and histiocytic cells by showing variable reactivity for CD1a and positivity for S-100 protein and CD68. Ultrastructurally, absence of Birbeck granules, a feature consistent with LC, epitomizes the lesional cells. Herein, we report a case of ICT in a new born emphasizing its histogenesis and clinical, morphologic, immunohistochemical, and ultrastructural features.