Tumour Markers

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.