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Oncogenisis and Tumor Markers
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Oncogenesis
• Human cancer development is a result of a genetic disease
• protoncogenes• Tumour suppressor genes.• Regulatory expression of these genes can be
seen in the normal cells and protein products of these genes are fundamental for normal cell function.
Examples:
• Oncogenes:
Ras, Myc, EGFR,c-erbB1,2,3.
• Tumour suppressor genes:
p53, Rb genes
Carcinogenesis• Multifactorial etiology.
• The tumour suppressor genes or oncogenes would be altered in the presence of carcinogens:
• Chemical carcinogens• Physical agents• Ionizing radiation • Viral agents• Others
Four common types of genetic changes
• Deletion : Loss of tumour suppressor genes • Mutation :p53, Ras• Inversion :Relocate the the oncogenes in• Translocation to DNA areas which will leads
inappropriate transcription.
• Subsequent accumulation of such growth promoting genetic defects forms the basis of current multi step process of tumourigenesis.
• This multi step process includes.
Initiation.
Promotion.
Tumour progression.
• Many of the known oncogenes and oncosupressor genes help control mitosis and apoptosis.
• Lack of this control would leads to development of malignancy.
• Genetic disease.
Tumour marker
• Substance or group of substance produced by the tumour
• Which can be used as a indicator to detect the presence of the tumour.
A tumour marker should be indicative of :
• Tumour susceptibility of the patient.
• Severity or virulence of the tumour.
• Prognosis of the disease.
• Tumour burden (Including metastasis) .
• Treatment response.
Types of tumour markers:
• Histopathological markers.
• Immuno markers.
• Genetic markers.
• Hormonal markers.
• Protein products of tumours
Carcino-embrionic antigen
Apoptosis related genes
• Bcl2 family:
Bcl2, Bcl XL , Bax , Bad.
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