Loss of Heterozygosity Status Analysis in Colonic Cancer Cells in a Group of Bangladeshi Patients

Auhtor: R Paul, M Kamal, F Begum, T Saha, S Afroz, MN Islam

Abstract:

Background: Colorectal cancer is a multifactorial disease process. A cross-sectional descriptive study was conducted among 35 cases of colorectal cancer patients to see the loss of heterozygosity (LOH) status analysis in those colonic cancer cells. Environmental and genetic factors both contribute to colorectal cancer. Etiology contributing from environmental factors includes dietary factors, obesity, alcohol intake, smoking and life style changes. The molecular events that leads to colorectal carcinoma is heterogeneous and includes genetic and epigenetic abnormalities. Methods: It is now believed that two pathogenitically distinct pathways namely the APC/b- caterin pathway and the microsatellite instability pathway are responsible for the development of colorectal cancer. Loss of heterozygosity in a cell represents the loss of normal function of one allele of a gene in which the other allele was already been inactivated. This term is mostly used in the context of oncogenesis. An inactivating mutation in one allele of a tumor suppressor gene that occurs in the parent's germ line cell is passed on to the zygote resulting in an offspring that is heterozygous for that allele. LOH occurs when the remaining functional allele in a somatic cell of the offspring becomes inactivated by mutation. This could cause a normal tumor suppressor gene to loss it's normal activity and results tumorogenesis. LOH is a common phenomenon in a variety of human cancers like colorectal carcinoma, urinary bladder cancer, osteosarcoma, prostatic carcinoma, cervical carcinoma, small cell lung cancer, non-small cell lung carcinoma, pancreatic carcinoma, breast carcinoma, malignant pituitary tumor and retinoblastoma. Results: LOH was most frequently found in chromosome 19p region (11.4% cases), followed by chromosome 12p (8.5% cases) and 4p (8.5% cases) and 5q regions (8.5% cases). Conclusion: Loss of heterozygosity in colonic cancer patients in our country was most frequently found in chromosome 19p region followed by chromosome 12p, 4p and 5q regions.

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