A. Syed Sameer

Molecular Gate Keepers Succumb to Gene Aberrations in Colorectal Cancer in Kashmiri Population, Revealing a High Incidence Area

Background/Aim: Colorectal cancer (CRC) is one of the leading malignancies worldwide and has been reported to show geographical variation in its incidence, even within areas of ethnic homogeneity. The aim of this study was to identify p53 and K-ras gene mutations in CRC patients in a Kashmiri population, and to assess whether these mutations are linked with clinicopathological parameters. Materials and Methods: Paired tumor and normal tissue samples from a consecutive series of 53 patients undergoing resective surgery for CRC were prospectively studied for p53 and K-ras gene mutations by PCR/single strand conformation polymorphism (SSCP). Results: Less than half (45%, 19/42) of the patients presented mutations in the p53 gene. Twenty eight mutations were found in the p53 gene, which comprised of 23 substitutions (17 transitions + 6 transversions), and five insertions. The 23 substitutions constituted 18 missense mutations, two nonsense mutations, and three silent mutations. Of the 28 mutations (7.14%) observed in this study, 2 were not previously reported for CRC samples and were identified as novel p53 mutations. A few patients (22.64%, 12/53) presented with mutations in K-ras, constituting 13 missense mutations, out of which 11 were G→A transitions, one was a G→C transversion, and one a G→T transversion. More than half (61.5%) of the mutations occurred in codon 12 whereas a few (38.5%) occurred in codon 13. One tumor contained missense mutations in both codons. Comparison of the mutation profiles of our patients with those of other ethnic populations and regions reflected both differences and similarities, indicating co-exposure to a unique set of risk factors. Conclusion: Mutations of the p53 and K-ras genes are some of the most common genetic changes in the development of human CRC. The high frequency of p53 gene mutations implicates p53 as a predominant factor for CRC in the high-risk ethnic Kashmiri population.

SMAD4 - Molecular gladiator of the TGF-β signaling is trampled upon by mutational insufficiency in colorectal carcinoma of Kashmiri population: an analysis with relation to KRAS proto-oncogene

BackgroundThe development and progression of colorectal cancer has been extensively studied and the genes responsible have been well characterized. However the correlation between the SMAD4 gene mutations with KRAS mutant status has not been explored by many studies so far. Here, in this study we aimed to investigate the role of SMAD4 gene aberrations in the pathogenesis of CRC in Kashmir valley and to correlate it with various clinicopathological variables and KRAS mutant genotype.MethodsWe examined the paired tumor and normal tissue specimens of 86 CRC patients for the occurrence of aberrations in MCR region of SMAD4 and exon 1 of KRAS by PCR-SSCP and/or PCR-Direct sequencing.ResultsThe overall mutation rate of mutation cluster region (MCR) region of SMAD4 gene among 86 patients was 18.6% (16 of 86). 68.75% (11/16) of the SMAD4 gene mutants were found to have mutations in KRAS gene as well. The association between the KRAS mutant genotype with SMAD4 mutants was found to be significant (P =< 0.05). Further more, we found a significant association of tumor location, tumor grade, node status, occupational exposure to pesticides and bleeding PR/Constipation with the mutation status of the SMAD4 gene (P =< 0.05).ConclusionOur study suggests that SMAD4 gene aberrations are the common event in CRC development but play a differential role in the progression of CRC in higher tumor grade (C+D) and its association with the KRAS mutant status suggest that these two molecules together are responsible for the progression of the tumor to higher/advanced stage.

Analysis of molecular aberrations of Wnt pathway gladiators in colorectal cancer in the Kashmiri population

The development and progression of colorectal cancer (CRC) is a multi-step process, and the Wnt pathways with its two molecular gladiators adenomatous polyposis coli (APC) and β-catenin plays an important role in transforming a normal tissue into a malignant one. In this study, we aimed to investigate the role of aberrations in the APC and β-catenin genes in the pathogenesis of CRC in the Kashmir valley, and to correlate it with various clinicopathological variables. We examined the paired tumour and normal-tissue specimens of 86 CRC patients for the occurrence of aberrations in the mutation cluster region (MCR) of the APC gene and exon 3 of the β-catenin gene by polymerase chain reaction-single-strand conformation polymorphism (PCR-SSCP) and/or PCR-direct sequencing. Analysis of promoter hypermethylation of the APC gene was also carried out using methylation-specific PCR (MS-PCR). The overall mutation rate of the MCR of the APC gene among 86 CRC cases was 12.8 per cent (11 of 86). Promoter hypermethylation of APC was observed in 54.65 per cent (47 of 86) of cases. Furthermore, we found a significant association between tumour location, tumour grade and node status and the methylation status of the APC gene (p ≤ 0.05). Although the number of mutations in the APC and β-catenin genes in our CRC cases was very low, the study confirms the role of epigenetic gene silencing of the pivotal molecular gladiator, APC, of the Wnt pathway in the development of CRC in the Kashmiri population.

DNA Repair Gene 8-Oxoguanine DNA Glycosylase Ser326Cys Polymorphism and Colorectal Cancer Risk in a Kashmiri Population

8-Oxoguanine DNA glycosylase (OGG1) is one of the important base excision repair enzymes that repair 8-oxoguanine lesion incorporated within the DNA of an individual by reactive oxygen species. The aim of this study was to detect the role of OGG1 Ser326Cys polymorphism in susceptibility to colorectal cancer (CRC) in a Kashmiri population. We investigated the genotype distribution of the OGG1 gene in 114 CRC cases in comparison with 200 healthy subjects. There was no significant association between OGG1 Ser326Cys polymorphism and CRC, but the homozygous Cys/Cys variant genotype was associated with an increased risk of colon cancer (p<0.05). This study suggests that the OGG1 polymorphism is not associated with the risk of development of CRC in the Kashmiri population in general but modulates the risk of cancer development in colon via interaction with many dietary factors.

Role of CYP2E1 genotypes in susceptibility to colorectal cancer in the Kashmiri population

Cytochrome P450 2E1 (CYP2E1) is a key enzyme involved in the metabolic activation of procarcinogens such as N-nitrosoamines and low-molecular-weight organic compounds. The main aim of this study was to determine whether CYP450 2E1 polymorphisms are associated with the risk of colorectal cancer (CRC). We investigated the genotype distribution of the CYP2E1 gene RsaI and a 96-base pair (bp) insertion in 86 CRC cases in comparison with 160 healthy subjects. We found the frequency of the CYP2E1 RsaI genotype to be 53.5 per cent (46/86) for c1/c1, 17.4 per cent (15/86) for c1/c2 and 29.1 per cent (25/86) for c2/c2, and the CYP2E1 98-bp insertion frequencies to be 63.9 per cent (55/86) for non-insertion (i/i), 22.1 per cent (19/86) for heterozygous insertion (i/I) and 36.0 per cent (12/86) for homozygous insertion (I/I) among CRC cases. We also found the CYP2E1 RsaI c2/c2 and CYP2E1 98-bp heterozygous i/I genotypes to be significantly associated with an increased risk of CRC (p = 0.01). We suggest that CYP2E1 polymorphisms are involved in the susceptibility to developing CRC in the ethnic Kashmiri population.

Squamous cell carcinoma of rectum presenting in a man: a case report

BackgroundPrimary squamous cell carcinomas of the colorectum are very uncommon. Until now, to the best of our knowledge, only 114 cases of squamous cell carcinoma in the colorectum exist in the reported literature. Here we report a case of squamous cell carcinoma of the rectum in the ethnic Kashmiri population in northern India.Case PresentationThe case of a 60-year-old male patient (Asian) with a pure squamous cell carcinoma of the rectum is presented here. The patient underwent a curative surgery with concomitant chemotherapy. Two years after the initial curative resection of the tumor he is still alive.ConclusionThe prognosis for squamous cell carcinoma of the colorectum is worse than for that of adenocarcinoma, because of the delayed diagnosis. The etiopathogenicity of squamous cell carcinoma of the colorectum is discussed. Surgical resection of the lesion seems to be the treatment of choice. Chemotherapy also helps in improvement of the prognosis.

Polymorphisms in the 3′UTR of the human leptin gene and their role in hypertension

Leptin is a protein hormone, mainly synthesized in adipocytes, that regulates the food intake and energy expenditure of the body. Rare mutations in the leptin gene cause obesity. Common polymorphisms of the leptin gene have been associated with obesity, however their association with arterial blood pressure has not been fully elucidated. The aim of the present study was to examine the effect of variants in the 3′ flanking region of the leptin gene on blood pressure in hypertensive subjects with high (35.2±5.12) and low (20.13±1.3) body mass index (BMI). Microsatellite polymorphisms and the C538T SNP in the 3′UTR of the leptin gene were screened in 362 subjects, and different biochemical and anthropometric parameters were measured. The levels of serum urea, creatinine, glucose, cholesterol, triglyceride, leptin and angiotensin II were determined in all subjects. A strong association of microsatellite polymorphisms with essential hypertension was found in subjects with a high BMI, but this association was only slight in subjects with a normal BMI. The C538T variant was not found in this population. The frequency of the Class I/Class I and Class I/Class II genotype for tetranucleotide polymorphisms was also significantly higher in the hypertensive compared to the normotensive group (p≤0.0001). In addition, a significant correlation was found between serum leptin and Class I/I and Class I/II genotypes. Linear regression analysis showed an independent correlation of leptinemia with BMI (p=0.019), while a notable correlation was found between serum leptin concentration and angiotensin II. The study confirmed that shorter alleles of microsatellites in the 3′ flanking region of leptin are significantly associated with hypertension, however, the underlying mechanism remains unknown.

Mutational and promoter hypermethylation status of FHIT gene in breast cancer patients of Kashmir

OBJECTIVE Fragile histidine triad (FHIT) gene located at chromosome 3p14.2 is a putative tumor suppressor gene involved in the pathogenesis of breast cancer. Both genetic and epigenetic alterations in FHIT have been implicated in breast carcinoma. In the present study, our main aim was to study the impact of these two kinds of alterations of FHIT gene in breast cancer patients of Kashmir. METHODS We screened a total of 130 breast cancer patients of Kashmir by PCR-SSCP followed by direct sequencing and methylation specific PCR. RESULTS Mutational screening of FHIT gene revealed significant amount of mutations [40.7% (53/130)] in five hot spot exons (exon 5-9), FHIT promoter was found to be hypermethylated in 59 of 130 [45.3%] breast cancer patients in our population. CONCLUSION In the present study we have shown a significant association between the mutational and hypermethylation profile of FHIT gene. Hence, we provide the first evidence to our knowledge that the significant association of FHIT mutation and hypermethylation leads to the complete inactivation of FHIT gene in patients with breast cancer. Silencing of the FHIT gene by promoter hypermethylation occurs in breast carcinomas, especially those with the significant amount of mutations.

GSTP1 I105V polymorphism and susceptibility to colorectal cancer in Kashmiri population.

The glutathione S-transferase (GST) enzyme encoded by the GSTP1 gene is one of the critical enzymes involved in detoxification of carcinogens. The substitution of isoleucine to valine residue at position 105 of the GSTP1 protein results in decreased enzyme activity and hence less capability of effective detoxification. Hence, we investigated the role of GSTP1 I105V polymorphism in modulating the risk of colorectal cancer (CRC) associated in a Kashmiri population. We designed a case-control study in which 86 CRC cases were studied for GSTP1 I105V polymorphism against 160 controls taken from the general population employing the polymerase chain reaction-restriction length fragment polymorphism technique. There was no significant association between GSTP1 I105V genotypes and the disease, but the Val/Val genotype was associated with an increased risk with some clinicopathological parameters (odds ratio=1.5; 95% confidence interval=0.55-4.57). This study suggests that the GSTP1 I105V polymorphism may modulate CRC risk in the Kashmiri population.

ACE Polymorphism in Colorectal Cancer Patients of Kashmiri Population – A Short Report

Aims: The angiotensin-converting enzyme (ACE) gene in humans has an insertion-deletion (I/D) polymorphic state in intron 16 on chromosome 17q23. This polymorphism has been widely investigated in different cancers and has been implicated as the risk factor for the development of various cancers. To investigate the ACE I/D genotype frequency in CRC cases in Kashmiri population and to correlate it with the known clinicopathological characters of CRC cases. Methods: We designed a case control study, where 86 CRC cases were studied for ACE I/D polymorphism against 150 controls taken from general population. The polymorphisms of ACE gene were investigated using polymerase chain reaction for detection of an I/D polymorphism. Results: Among CRC (86) cases we found the frequency of ACE DD genotype to be 41.86 % (36/86), II 13.95% (12/86) and DI 44.2% (38/86). There was no significant association between the ACE I/D genotype with any of the known clini- copathological characters. Conclusion: The ACE I/D polymorphism is not a significant risk factor in the CRC carcinogenesis in our population.