Date post: | 19-Jun-2015 |
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Health & Medicine |
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CANCER
Dr Vijay Marakala,M.DBiochemistry,SIMS&RC.
Cancer is malignant growth (un controlled growth)
and proliferation of cells.
•Uncontrolled growth of a single altered cell. = Mutations = Cancer•Cancer cells grow faster, adapt better.•They live at the cost of our living.
Normal cells Mutated cells Proliferation of mutated cells
Uncontrolled growth Invasion Metastasis
MORPHOLOGICAL CHANGES IN CANCER CELL
Multilayer
Growth
Grow over one
another
Motility
Rounder
Shape
Due to loss of contact inhibition
BIOCHEMICAL CHANGES IN CANCER CELL
Altered synthesis of
certain growth factors
Lactic acidosis
↓Catabolism of
pyrimidines
↑Synthesis of DNA and
RNA
Altered gene regulation
Stimulates anabolic processes
NOMENCLATURE AND CLASSIFICATION OF CANCERS
CarcinomasCancer of cells or organs
derived from either ectoderm or endoderm
Cancers of epithelial tissues, nervous tissues,
glands etc
SarcomasCancers of tissues of mesodermal origin
Cancers of bone, cartilage, connective
tissue, muscle etc
B/O the 3 embryonic germ layers from which tissue or organ is derived
NOMENCLATURE AND CLASSIFICATION OF CANCER
CarcinomasAdenocarcinoma
Squamous cell carcinoma
Gliomas
Sarcomas
Osteosarcoma
Fibrosarcoma
CAUSES FOR CANCER
EstrogenOCP
Anabolic steroids
Hormonal
Hepatitis B virus
Retro viruses
Biological
Cigarette smoke
Aflatoxins
Chemical
X-raysγ-rays
UV rays
Physical
MECHANISM OF CARCINOGENESIS
Radiation Damage to DNA
Direct effect
• Single or double strand breaks• Elimination of purine/pyrimidine bases• Cross-linking of strands• Formation of pyrimidine dimers
Indirect effects
• Production of free radicals
MECHANISM OF CHEMICAL CARCINOGENS
• Carcinogens are generally electrophiles
• Electrophiles readily attack nucleophilic group of DNA
• Carcinogens may bind covalently to cellular DNA
Direct acting Procarcinogens
Target DNA
MECHANISM OF CHEMICAL CARCINOGENS
Procarcinogens
Procarcinogens Proximate carcinogens
Ultimate carcinogens
MECHANISM OF BIOLOGICAL CARCINOGENS
ONCOGENIC VIRUSES
Virus infect host cell
DNA virus binds tightly to host cell DNA
Altered gene expression
Altered protein [oncoprotein]
MECHANISM OF HORMONAL CARCINOGENS
• Endometrial carcinoma
Estrogen
• Breast cancer
OCP
• Liver carcinoma
Anabolic steroids
MOLECULAR BASES OF CANCER
• Normal genes which inhibit cell division
Tumor suppressor gene
• Normal genes which stimulate cell division
Proto-oncogene
• Genes capable of causing cancer
Oncogenes
Balance and imbalance between factors stimulating and inhibiting cell growth
Inhibitors-
Stimulators+
Tumour supressor
gene
Proto-oncogene
Inhibitors-
Stimulators+ +
oncogenes
Oncogenes
Tumour supressor
gene
ACTIVATION OF PROTO-ONCOGENE TO ONCOGENE
Viral insertion into chromosome
Chromosomal translocation
Gene amplification
Point mutation