23. VIRUSES NEOPLASMS
DNA VIRUSES
Human papilloma virus Cervical Ca, warts, ano-
genital carcinoma
Herpes simplex virus II Cervical carcinoma
Epstein-Barr virus NPCa, African Burkitt’s
Human Herpes virus 8 Kaposi’s sarcoma
Hepatitis B virus Hepatocellular Ca
Herpes simplex virus 6 Certain B cell
(HBLV) lymphomas
24. VIRUSES NEOPLASMS
RNA VIRUSES
Human T-cell leukemia virus I Some T-cell
leukemia,
lymphoma
Human T-cell leukemia virus II Some cases of
hairy
cell leukemia
Human immunodeficiency virus I Lymphoma;
Kaposi’s
sarcoma
25. VIRAL AGENTS: RNA viruses
Human T-cell Leukemia Virus [HTLV]
a retrovirus
tropism: CD4+ cells
mechanism: Tax protein
transcription c-fos, c-sis, IL-1 and IL-2
Viral replication T cell proliferation
29. ONCOGENE FAMILY
Classification of Oncogenes
A. Secreted Growth Factors
c-sis, hst
B. Cell Surface Receptors
erb B, fms, ret, trk, fes, fms Components of
signal transduction
C. Intracellular Transducers pathways
c-src, c-abl, mst, ras
D. DNA-binding Nuclear Proteins
myc, jun, fos
E. Regulators of the Cell Cycle
bcl, bax, bad
30. Classification of TS genes
A. Cell Adhesion Molecules
APC, DCC
B. Regulators of the Cell Cycle
RB1, Tp53
32. Proto-oncogene DNA
Mutation within Multiple copies Gene moved to
the gene of the gene new DNA locus,
under new controls
New promoter
Oncogene
Hyperactive
growth- Normal growth-
stimulating Normal growth-
stimulating
protein in stimulating
protein
normal protein
in excess
amount in excess
50. Most normal adult tissues have NO telomerase activity
Telomerase activity is present in 90% of tumors
Telomeres- specialized structures at chromosome
ends generated and maintained by telomerase
Telomerase- ribonucleoprotein enzyme which
preserves the integrity of telomeres
* key component in immortalization of cancer
cells
Telomere length- represents a molecular clock
that determines the life span of the cell
51. Angiogenesis
• Process of new blood vessel formation.
• Clinical importance:
– Tumor vessel number correlates positively with
risk and degree of dissemination.
– Several cytokines that stimulate endothelial cell
proliferation also stimulate proliferation of
malignant cells.
52. • Formation of new blood vessels from existing
vascular bed
• Carried out by endothelial cells (EC) and extra
cellular matrix (ECM)
• Regulated by angiogenic factors (inducers and
inhibitors)
* A tumor is unable to grow larger than 1 mm3
w/o developing a new blood supply