HBG 26 ( Cancer Genetic)

• Cancer is a genetic disease
• Cancer arises from normal cells that have undergone mutation
• Cancer is caused by multi-step accumulation of mutations
• Key feature of cancer is abnormal rapid cell replication
• Spontaneous and environment factors contribute to cancer
• Proto-oncogenes/ Tumour suppressor genes
• Proto-oncogenes are genes that produce proteins driving cell proliferation, division, and growth
• Cancer can be familial or sporadic
• Oncogenes are mutated proto-oncogenes causing rapid cell proliferation and uncontrolled growth
• Mutated Tumour Suppressor Genes lead to uncontrolled and rapid cell growth, making cells cancerous
• Tumour suppressor genes produce proteins that slow cell proliferation, division, and growth
• Examples of Proto-oncogenes/oncogenes
• Transcription Factors
• Growth factors and growth factor receptors
• Some transcription factors transcribe genes causing cell proliferation and growth
• Growth factors and receptors mutations increase cell proliferation and growth
• Cell Signaling Proteins
• Growth signals are transmitted from outside to inside the cell, leading to cell proliferation and growth
• Mutations of these signaling proteins amplify the growth signals
• Examples Tumour Suppressor Genes
• pRB (retinoblastoma protein) slows cell proliferation and growth
• Mutation disables pRB function, leading to uncontrolled cell growth
• Cell cycle regulation proteins and cell-death proteins are involved in controlling cell growth and apoptosis
• Mutation of these proteins causes retention of mutated cells, e.g., p53
• DNA repair proteins
• DNA repair proteins help repair damaged DNA
• Mutation of DNA repair proteins leads to poorly repaired damaged DNA
• Hereditary/Familial cancer
• Genetic changes first happened in germ cells
• Mutations detected in all cells in the body
• Common in young patients
• Sporadic cancer
• Genetic changes first occur in somatic cells
• Mutations detected only in tumor cells
• No pattern in family tree
• Usually happens in ageing population
• Hallmarks of Cancer
• Sustaining Proliferative Signal
• Mutations of growth factor and its receptors cause rapid cell growth
• Overexpression/Upregulation of growth factor receptors