Nosheen Masood

Mutational spectrum of Gelsolin and its down regulation is associated with breast cancer.

Cytoskeletal rearrangement occurs in variety of cellular processes and involves a wide spectrum of proteins. Gelsolin super family proteins control actin organization by severing and capping filament ends and nucleating actin assembly. Gelsolin is the founding member of this family and plays important role in pathogenesis of human neoplasia. This study aimed to investigate the germline mutations and expressional profile of Gelsolin in human breast cancer tissues. For germ line screening PCR-SSCP technique was used while expression was analyzed through quantitative real time PCR. Different types of mutations were observed in Gelsolin coding regions on exons 4, 10, 11, 14 and 15. These mutations include 3 missense nonsynonymous substitution mutations, 2 deletions, 1 insertion and 1 synonymous substitution mutation. Gelsolin transcript level was found significantly lower in breast tumor tissues compared to control samples (p=0.03). Low level of Gelsolin was found in metastatic patients (p=0.002) and patients who died from breast cancer (P=0.03) compared to disease free patients at final follow up. This study shows that level of Gelsolin is down regulated in breast cancer tissues and is linked with metastasis development and death in patients. It is concluded that genetic changes in coding regions of Gelsolin can potentially contribute to genetic instability. These genetic variations and expressional correlation with patient survival may prove to be of significant importance.

Genetic Deletions of GSTM1 and GSTT1 in Head and Neck Cancer: Review of the Literature from 2000 to 2012

Head and neck cancer is one of the leading causes of deaths worldwide. Two genes GSTM1 and GSTT1 involved in phase II of carcinogen detoxification have been frequently studied in the literature. Their null genotypes are thought to be associated with increased head and neck cancer risk. However, the published reviews are not up to date and many important papers have been skipped. The current literature review was restricted to the null genotypes of the GSTM1 and GSTT1 genes with special emphasis on the genotypic status. We found that the size of study sample varied greatly and the oral cavity cancer was more influenced by GSTM1 and GSTT1 gene deletions. With respect to ethnicity Asians are more prone to head and neck cancers with these null genotypes as compared to Europeans and Americans. The current review showed significant associations (OR=9.0, 95%CI; 1.4-9.5; OR=3.7, 95%CI; 1.4-9.5) of GSTM1 and GSTT1 null genotypes with head and neck cancers. Review confirms the data of previous reviews that GSTM1 and GSTT1 gene polymorphisms may be risk factors for cancer initiation.

Mutational analysis of xenobiotic metabolizing genes (CYP1A1 and GSTP1) in sporadic head and neck cancer patients

CYP1A1 is the phase I enzyme that detoxifies the carcinogen or converts it into a more electrophilic form, metabolized by phase II enzymes like GSTP1. These detoxifying genes have been extensively studied in association with head and neck cancer (HNC) in different ethnic groups worldwide. The current study was aimed at screening genetic polymorphisms of genes CYP1A1 and GSTP1 in 388 Pakistani HNC patients and 150 cancer-free healthy controls, using PCR-SSCP. No already known variants of either gene were found, however a novel frameshift mutation due to insertion of T (g.2842_2843insT) was observed in the CYP1A1 gene. A statistically significant number (5.4%) of HNC cases, with the mean age of 51.75 (±15.7) years, presented this frameshift mutation in the conserved domain of CYP1A1. Another novel substitution mutation in was found in the GSTP1 gene, presenting TA instead of AG. The g.2848A > T polymorphism causes a leucine-to-leucine formation, whereas g.2849G > A causes alanine-to-threonine formation at amino acid positions 166 and 167, respectively. These exonic mutations were found in 9.5% of the HNC patients and in none of the controls. In addition, two intronic deletions of C (g.1074delC and g.1466delC) were also found in 11 patients with a mean age of 46.2 (±15.6) years. In conclusion, accumulation of mutations in genes CYP1A1 and GSTP1 appears to be associated with increased risk of developing HNC, suggesting that mutations in these genes may play a role in the etiology of head and neck cancer.

Prostate cancer and glutathione S-transferase deletions.

GSTM1 and GSTT1 gene polymorphisms have been studied in many populations to evaluate their association with prostate cancer risk with contrasting results. The current study was aimed to find out the association of GSTM1 and GSTT1 gene polymorphisms with prostate cancer in Pakistani men. This case control study included pathologically confirmed prostate cancer patients and age matched male controls. Epidemiological data was collected by a standard questionnaire and presence or absence of GSTM1 and GSTT1 gene was observed by multiplex PCR using CYP1A1 as housekeeping gene. Prostate cancer was more prevalent in age of >60 years and most of the patients were at stage IV (70 %) and have undergone surgery. Family history of cancer, smoking, metastasis and surgery were found to be significant (P<0.05) risk factors in prostate cancer development. Gleason score 7 was most prevalent (40.5 %) in prostate cancer patients. Source of drinking water, residential area, occupation, eating habits and number of family members had no association (P>0.05) with prostate cancer risk. No significant association was found when comparing GSTM1 (OR=0.78) and GSTT1 (OR=0.89) gene deletions with prostate cancer risk. Smoking and TNM staging were also not associated with deletion of GSTM1 and GSTT1 genes. Comparison of dual null deletion of both genes with prostate cancer also showed non-significant associations. Deletion of GSTM1 gene at stage IV prostate cancer patients was significantly higher compared with other stages of cancer while no significance was shown by GSTT1 gene deletion. GSTM1, GSTT1 and deletion of both GSTM1 and GSTT1 genes do not contribute towards increased risk of prostate cancer in Pakistani population.

Genetic variations and head and neck cancer risks

Variations in CYP1A1, GSTM1, GSTT1 and GSTP1 in head and neck cancer have been frequently found in literature. But these studies give an overview of these genetic variations in different populations. The current mini review focus on the analysis of these genetic variations at DNA, mRNA and protein levels in the same study group. Eight publications were reviewed on the same study samples yielding results at DNA, mRNA and protein levels. At DNA level, CYP1A1 showed significantly higher mutations in head and neck cancer patients compared to controls at g.2842A>C and g.2842_2843insT. GSTM1 and GSTT1 showed deletion polymorphisms and heterozygous deletion confers protection against cancer. Mutations were also found in GSTP1 at g.2848A>T, g.2849G>A, g.1074delC and g.1466delC. mRNA and protein expressional analysis revealed underexpression of CYP1A1, loss or underexpression of GSTM1 and GSTT1 and overexpression of GSTP1. In addition an unusual intronic variant of GSTP1 mRNA was also found, retaining the intronic portion between exons. The current review gives a complete study overview regarding CYP1A1, GSTM1, GSTT1 and GSTP1 variations at DNA, mRNA and protein levels in head and neck cancer. The review is helpful in designing a new experiment or gene therapy for head and neck cancer patients.

Unusual Intronic Variant in GSTP1 in Head and Neck Cancer in Pakistan

In the present case control study mRNA expression of the GSTP1 gene, encoding a phase II enzyme that detoxifies via glutathione conjugation, was investigated using semiquantitative PCR followed by SSCP for 49 confirmed head and neck (HN) cancer and 49 control samples. It was found that GSTP1 was upregulated in significantly higher number of cancers (OR 4.2, 95% CI 1.2- 15.3). Grade wise correlation was also observed with more up regulation in patients with more advanced grades of HN carcinomas. We also found that 5 patients showed variation in mRNA with a larger product size than expected. Sequencing revealed insertion of an intronic segment between the 6th and 7th exon of the GSTP1 gene. Germline screening was performed showing mobility shifts which suggested mutation at the DNA level resulting in intronic portion retention. This study is of prime importance for drug design and treatment selection to overcome increased resistance of HN cancers to drugs due to alteration in the GSTP1 gene.

Entangling Relation of Micro RNA-let7, miRNA-200 and miRNA-125 with Various Cancers

Involvement of micro RNAs (miRNA) is currently the focus for cancer studies as they effect the post transcriptional expression of different genes. Let-7 family is among the firstly discovered miRNAs that play important role in cell proliferation and dysregulation leading to cell based diseases including cancer. Another family, miRNA-200 prevents transformation of cell to malignant form and tumor formation by interacting with epidermal mesenchymal transition (EMT). Similarly miRNA-125 controls apoptosis and proliferation by affecting multiple genes involved in transcription, immunological defense, resistance against viral and bacterial infections that ultimately leads to cell proliferation, metastasis and finally cancer. All of these micro RNAs are known to be either upregulated or downregulated in various cancers. Current review is focused to elaborate the role of these three families of micro RNAs on different genes that ultimately cause cancer. In conclusion we can say that the miRNAs discussed here are mostly downregulated in various cancers with some exceptions when upregulation of miRNA-125 may be attributed to cancer formation.Involvement of micro RNAs (miRNA) is currently the focus for cancer studies as they effect the post transcriptional expression of different genes. Let-7 family is among the firstly discovered miRNAs that play important role in cell proliferation and dysregulation leading to cell based diseases including cancer. Another family, miRNA-200 prevents transformation of cell to malignant form and tumor formation by interacting with epidermal mesenchymal transition (EMT). Similarly miRNA-125 controls apoptosis and proliferation by affecting multiple genes involved in transcription, immunological defense, resistance against viral and bacterial infections that ultimately leads to cell proliferation, metastasis and finally cancer. All of these micro RNAs are known to be either upregulated or downregulated in various cancers. Current review is focused to elaborate the role of these three families of micro RNAs on different genes that ultimately cause cancer. In conclusion we can say that the miRNAs discussed here are mostly downregulated in various cancers with some exceptions when upregulation of miRNA-125 may be attributed to cancer formation.

Genetic Susceptibility to Oral Cancer due to Combined Effects of GSTT1, GSTM1 and CYP1A1 Gene Variants in Tobacco Addicted Patients of Pashtun Ethnicity of Khyber Pakhtunkhwa Province of Pakistan

Associations of GSTT1, GSTM1 and CYP1A1 gene variants with risk of developing oral cancer were evaluated in this study. A case-control study was conducted in Pashtun population of Khyber Pakhtunkhwa province of Pakistan in which 200 hospital based oral cancer cases and 151 population based healthy controls exposed to similar environmental conditions were included. Sociodemographic data were obtained and blood samples were collected with informed consent for analysis. GSTM1 and GSTT1 were analysed through conventional PCR method while specific RT-PCR method was used to detect CYP1A1 polymorphisms. Results were analyzed for conditional logistic regression model by SPSS version 20. The study shows that patients with either GSTM1 or GSTT1 null genotypes have significantly higher risk of oral cancer (adjusted odds (OR): (3.019 (1.861-4.898) and 3.011(1.865-4.862), respectively), which further increased when either one or both null genes were present in combination (adjusted odds (OR): (3.627 (1.981-6.642 and 9.261 (4.495-19.079), respectively). CYP1A1 rs4646903 gene variants individually showed weak association OR: 1.121 (0.717-1.752); however, in the presence of GSTM1 and/or GSTT1 null genotypes further increasing the association (adjusted odds (ORs): 4.576 (2.038-10.273), 5.593 (2.530-12.362) and 16.10 (3.854-67.260 for GSTM/GSTT null and CYP1A1 wild type, GSTM/GSTT either null and CYP1A1 variant alleles, and all 3 gene polymorphisms combinations, respectively). Our findings suggest that presence of GSTM1 and/or GSTT1 null genotypes along with variant alleles of CYP1A1 may be the risk alleles for oral cancer susceptibility in Pashtun population.

Protection against laryngeal and pharyngeal carcinoma: Heterozygous vs. homozygous deletions of GSTM1 and GSTT1

Deletions in GSTM1 and GSTT1 genes are considered to be a risk factor for cancer development but the exact location of these deletions in the genome was unknown. Three main objectives of the current study were to: (a) identify the boundaries of these deletions in the human genome, (b) screen homozygous (−/−) and heterozygous (+/−) deleted, as well as homozygous present (+/+) individuals using PCR assays, (c) detect associations of pharyngeal (PC) and laryngeal cancer (LC) with the respective genotypes. In total, 102 PC and 92 LC patients were screened and compared with 150 controls. PCR mapping and sequencing revealed a 6 kbp deletion for GSTM1 and a 9 kbp deletion for the GSTT1 gene. The mean age of PC cases was 48.1 (±16.7) years; for LC cases it was 48.5 (±17.4) years and for controls 46 (±17.7) years. The OR (odds ratio) for the GSTM1 null genotype in PC and LC cases was 10.2 and 1.0 (95% CI 5.04–20.7 and 1.1–1.7) respectively. Similarly, for GSTT1 the OR was 4.02 with a 95% CI of 2.3–7.1 in PC cases. For LC cases the OR was 0.8 with 95% CI of 0.4–1.7. A non-significant number of LC and PC patients had heterozygous deletions of GSTM1 compared to controls (OD 0.5, 95% CI 0.2– 1.6 and OR 0.5, 95% CI 0.2– 1.5 respectively). The GSTT1 gene also showed a non-significant association in PC (OD 0.9, 95% CI 0.4–1.9), as well as in LC patients (OD 0.7, 95% CI 0.3–1.7). The homozygous genotype was significantly associated with PC and LC, whereas the heterozygous was not so. The GSTM1 (−/−) and GSTT1 (−/−) genotypes are a risk factor for LC and PC, whereas the (+/−) genotypes are not.

Epidemiological factors related to GSTM1 and GSTT1 genes deletion in colon and rectum cancers: A case-control study

BACKGROUND GSTM1 and GSTT1 are phase II enzymes which provide chemical defense to cells. OBJECTIVE This study was designed to evaluate association of GSTM1 and GSTT1 deletion along with epidemiological factors with risk of colon and rectum cancers. METHODOLOGY Multiplex PCR was used for cancer patients as well as age and gender matched cancer free controls. RESULTS Mean age of patients and controls was 45.5 (± 14.6) and 43.5 (± 18.08) years respectively. Among epidemiological factors; gender, age ≥ 50 years, active/passive smoking, naswar addiction, residential area, family history, red meat, fruit and vegetable intake showed no association with CRC (P ≥ 0.05). Symptoms of CRC like altered bowel habits (70%) was more common compared with other symptoms. GSTM1 (P ≤ 0.05) and GSTT1 (P ≤ 0.05) deletions were found to be significantly associated with CRC compared with controls. Association of epidemiological factors like gender, active/passive smoking, naswar addiction, residential area and family history were associated neither with GSTM1 deletion nor to GSTT1 deletion in both cancers (P ≥ 0.05). Significant association was present between stage III and GSTM1 (CI 95% 0.15-1.39) as well as GSTT1 (CI 95% 0.14-2.44) deletion in CRC. CONCLUSION These results suggest that GSTM1 and GSTT1 deletion were associated with increased risk of colon and rectum cancer in Pakistani population.