Its easy and clear way to learn how normal cell converted to cancerous cell.Both in vivo and vitro cell transformation mechanism explained well.....

2. CELL TRANSFORMATION
Conversion of normal cells to cancerous cells
Arslan Ali
Department of microbiologyGovt.College University Faisalabad.

3. INTRODUCTION
Cell transformation is a process in which the addition of certain
malignant characteristics in cell due to alteration in genetic
material.
• induced by chemicals, carcinogens, radiations, viruses .

4. History
• In 1901 Hugo deVries first used the term mutation to describe the sudden
heritable phenotypic changes in evening primrose.
• In 1904T.H.Morgan reported white eyed drosophila in the population of red
eyed flies.
• In 1928 H.J. Muller first use x-rays to induce mutation in fruit fly

5. How normal cells converted to cancerous cells (In Vivo)

6. 1. Radiations
• UV radiation causes pyrimidine dimerization of DNA which causes deletion/ insertion of nucleotide i.e. genetic
makeup changes
• It leads to conversion of proto-oncogenes (normal genes) to oncogenes
• These oncogenes produces some malicious products which causes blockage of UV specific endonuclease
enzyme (repair enzymes).
• Due to which DNA cannot be repaired and it leads to conversion of normal cell to cancerous cell.

7. 2. MutationA. Point Mutation:
Changes in single nucleotide sequence of gene. It effects the cell in two ways:
a. Either by blocking p53 gene which is required for apoptosis.Then the cell will continue to divide
b. Or by the change of k-RAS gene to mutant KRAS.
• KRAS is a gene required for production of growth related K-RAS proteins when combine with miRNA.
• If KRAS remains hyperactive then this mutant Ras keeps signaling molecules ON , and cells continue to divide

8. b. Chromosomal Mutation
• It occurs in case of Retinoblastoma (eye cancer)
What happens?
• Retinoblastoma (Rb) is a protein that acts as a regulator in cell cycle control.
Phosphorylation of Rb release E2F that will be required for production of other proteins
that regulate the cell cycle.
• During mutation in Ch-18 then Rb mutated and transcriptional factor E2F remains
active.As a result cells continue to divide

9. c. Insertion/ WithViruses
• It occurs in case of Avian LeukosisVirus
• In it virus inserts its own gene between the normal gene
• Like there is a gene which is responsible for production of myc
protein.
• Virus inserts its own gene within it and causes modification in it.
• Myc protein has two parts: regulator and activator region.Virus
blocks the regulator region by inserting its gene due to which
myc continuously produces and causes the cells continue to
divide.

10. d) Translocation
• It occurs in case of Burkett's lymphoma
• Ch-8 contain gene sequence for ‘myc’ protein which is transcriptional factor. If ‘myc’ gene get
gain of function mutation then cells continue to divide. So Ch-8 contains tight regulator for it
• But when it is translocated to Ch-14 which has heavy IG chain then it continuously produced
along with antibodies
• Due to which cell continuously divides.

11. Generation of Immortal Cell Lines
(In Vitro)

12. 1. Spontaneous immortalized cells
• The best method of achieving continuous cell lines is through
cancerous cells which resist senescence.

13. 2. Infection with transforming virus
• SV-40 virus produces largeT antigen which block the RB &
p53 genes , both controllers of cell cycle.
• It is mostly used for human fibroblasts cells
• Other viral genes includes those from HPV such as E6 & E7.

14. 3.Transfect cells with telomerase gene
• The most well known immortality gene is telomerase HTERT
• Telomerase is able to extend the DNA sequence of telomeres
thus abating the senescence process and enabling the cells to
undergo infinite cell divisions.
• Mostly used for mesenchymal stem cells.
4.Transfection with Mutant-Ras gene

15. 5. Exposure to Ionizing Radiations
• UV radiations
• X- rays
• Gamma rays
6. Exposure to chemical carcinogens
• Benzo[alpha]pyrene
• Formaldehyde
• Vinyl chloride
• Arsenic

16. 7. Hybridoma
• Normal cell fuses with cancerous cell to form hybridoma that
have the property to divide continuously and produce immortal
cell lines.

17. Examples of immortalized cells
• A549- from cancer patient lung tumor
• HeLa cells- from cervical cancer patient, Henrietta Lacks, widely
used human cell line
• BHK cells- used for transformation by treating with human
Adenovirus D, Reovirus 3 etc.

18. Characteristics Of
Transformed Cells

19. 1. Immortalization
• The acquisition of an infinite life span by a cell is referred to as
immortalization.
• Most of normal cells have limit life span of 20-100 generations.
• But tumor cells have infinite life span as they go on producing
continuous cell lines.

20. 2. Aberrant Growth Control
• The transformed cells or cells from tumors , grown in culture
show many aberrations with respect to growth and its control.

21. 3.Tumorogenicity
• Cell transformation is a complex process that often results in
formation of neoplastic cells.
• The cells obtained from malignant tumors are already
transformed

22. 4. Contact Inhibition
• The transformed cells loss the ability of contact inhibition as a
result monolayer do not form properly.
• This can be observed by morphological changes in disoriented
and disorganized monolayer

23. 5. Low Serum Requirement
• In general transformed cells or tumor cells have low
serum dependence than normal cells.
• This is mostly due to secretion of autocrine growth
factors by transformed cells:
CSF
TGF alpha
IL 1,2, 3
Gastrin releasing peptide

24. 6. Anchorage Independence
• There occur several changes on surface of transformed
cells.
• These include alteration in the cell surface glycoprotein &
integrin, loss of fibronectin and some transformed cells
totally lack CAMs
• It leads to decreased in cell-cell & cell-substrate adhesion.
• Such cells grow in disorganized fashion

25. applications

26. 1.Screening of the anti-cancerous drugs
2.To determine the cytotoxicity
3.Production of viral drugs
4.In-vitro screening of several drugs
5.Cell fusion techniques
6.Cell based bio-assay
7.Genetic manipulation
8.Study of the effects of toxins using cell lines.