This document discusses the genetic basis of cancer. It explains that cancer occurs due to genetic defects that cause normal cells to grow uncontrollably and become cancerous. These genetic changes can involve mutations in proto-oncogenes which become active oncogenes, inactivation of tumor suppressor genes, defects in programmed cell death genes and DNA repair genes. The accumulation of such genetic defects and mutations in regulatory genes drives the development and progression of cancer.

2. GENETIC BASIS OF CANCER
GENETIC BASIS OF CANCER

3. HAFIZ M WASEEM UNIVERSITY
OF EDUCATION LAHORE

4. CONTENTS
INTRODUCTION
WHAT IS CANCER?
● HISTORY
ONCOGENES AND CANCER
● PROTO-ONCOGENES
● TYPES OF ONCOGENES
TUMOR SUPPRESSOR GENES AND TWO -HIT
MODEL
● TWO-HIT MODEL
THE GENES REGULATE PROGRAM CELL
DEATH (APOPTOSIS)
DNA REPAIR GENES
● OVERVIEW
CONCLUSION
REFERENCES

5. ● The aggregation of genetic defects can
cause the normal cells to become cancerous
cells and cause the cancerous cells to
become more dangerous.
● Cancer means uncontrolled cell division
and growth .
● Cancer may be occured by genetic basis or
environmental conditions.
● These genetic changes may occur at
different levels, from gain or loss of single
chromosomes or mutation may also occur
at complete sequence of DNA nucleotides.
INTRODUCTION

6. ❏ Hippocrates first time used the term cancer.
❏ In 1940 ,Virchow defined cancer “uncontrolled growth of cells ” and he called them leukemia.
❏ Boveri explained the role of abnormal chromosomes in cancers.
❏ He proposed a theory that has has four main points
First: Cancer is a cellular problem .
Second: The cancers originate from a single cell.
Third: The cell has an abnormality of its chromosomal constitution.
Fourth: The chromosomal abnormality which is passed on to all the descendants of the cell of
origin is the cause of rapid cell proliferation.
HISTORY

7. There are four classes of normal regulatory genes that become the principal target of genetic demage.
❖ The growth promoting genes (Proto Oncogenes genes )
❖ The growth inhibiting genes (Tumor suppressor gene)
❖ The genes that regulate programmed cell death (Apoptosis)
❖ DNA repair genes
GENES AND CANCER

8. ★ The normal form of genes is known as
proto-oncogenes.
★ Proto-Oncogenes perform multiple
functions in growth and proliferation.
★ Mutations convert these proto-oncogenes
into cellular oncogenes that are involved in
tumor developments
★ While muted or destructive forms of genes
are called oncogenes.
Proto Oncogenes oncogenes
multiple division cancer
PROTO-ONCOGENES

9. There are two common types of oncogenes
1: : A special protein that controls cancers growth and spread.This type of gene is mostly present
in cancerous cells.For example breast and ovarian cancer cells.
TYPES OF ONCOGENES
HER2

10. RAS family of genes which makes proteins involved in cell communication pathways, cell growth, and cell
death.
RAS
ONCOGENES

11. ➔ Tumor suppressor genes also called growth
inhibiting genes.
➔ Henry Harris and his colleagues first identified the
tumor suppressor genes in 1969.
➔ Tumor suppressor genes control cell cycle, cell proper
growth and control the cell death or apoptosis.
➔ These genes control the normal growth of cells and
their normal multiplications
➔ When tumor suppressor genes do not work properly
or they become mutant as a result abnormal genes
formed .
➔ As a result normal cells convert into cancerous cells.
TUMOR SUPPRESSOR GENES

13. ❏ Loss of apoptotic genes allows the
cancerous cells to increase their number.
❏ Thus within a short time, muted cells divide
many times and become cancerous cells.
THE GENES REGULATE PROGRAM CELL DEATH (APOPTOSIS)

14. DNA REPAIR GENES
➔ Tumor suppressor genes BRCA1, BRCA2, and p53 all are DNA repair genes.
➔ If any individual has an error in DNA repair gene ,then maybe mistakes appeared when genes would
be copied.
➔ while those mistakes become mutations.At the end these mutations become cancer.
EXAMPLES:
❖ Lynch syndrome is an example of the inherited form of cancer.
❖ Colorectal cancer is another example of inherited kind of cancer.
DNA REPAIR
GENES

15. CONCLUSION
❏ Cancer is a genetic disorder in which normal cells lose their normal growth.
❏ The basis mechanism of cancer cells is either a result of mutation in somatic cells or germ line
cells.
❏ Cancer is a multifactorial disease that is influenced either by environmental factors or different
genes.
❏ Cancer cells has genetic defects affecting apoptosis, cell cycle and regulation.
CONCLUSION

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