CARCINOGENESIS AND ITS AFFECT IN DNA…. PRESENTED BY:- Anamika Das M.Sc Biotechnology 2 nd semester Roll no:-06 Gauhati University. CARCINOGENESIS.
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M.Sc Biotechnology 2nd semester
Tumors develop in those tissue in which cellular homeostasis has been distributed by Hyperplasia,dysplasia or regenerative changes.
e.g- inhaled asbestos,certain dioxins and tobacco smoke.
chemical substances, carcinogenic action of physical agents & the action of carcinogenic transformation of viruses.
geographical factor,nutritionfactor,sex, age etc.
e.g-benzpyrene-7 ,8-diol -9 ,10-epoxide(BPDE)
Cytochrome p-450(a liver enzyme)
Benzpyrene-7, 8 diol
Causes liver cancer
Fig: conversion of benzpyrenes into carcinogenic derivatives by liver enzymes.
The DNA adduct forming compound aflatoxin B1 appear to be major cause of liver cancer in devloping countries.
Another major source of ROS & RNS leading to cancer is inflammation stemming from chronic infection.
UVB radiations main effect is DNA damage cause by its direct interaction with the molecule,whlie UVA radiation’s toxicity mainly comes from oxidative damage to skin cell components.
DNA encodes the genetic information which provides instruction for the structure and function of the living organism.
The effects of UVB on DNA are mostly caused by the formation of these dimers between two adjacent pyrimidines on the same strand.
The human body has inbuilt system of DNA repair,known as “Nucleotide excision repair” & “Base excision repair” to recognize and eliminate such changes.
Tumor suppressor genes tend to be down regulated and/or inactivated by mutations that may induce cancer transformation.