Carcinogenesis And Carcinogenic Agents Flashcards
Hallmarks of cancer
1.Avoids immune destruction
2. Evades growth suppressors
3.Enables replicative immortality
4.Tumor promoting inflammation
5.Activating invasion and metastasis
6.Genomic instability
7.inducing angiogenesis
8.Resisting cell death
9.Deregulating cellular energetics
10.sustaining proliferation signalling
What are the carcinogenic agents
1.chemical carcinogens
2.Radiation effect
3.uv Rays
4.oncogenic microbes (viruses)
What are the major chemical carcinogens
1.Organic chemicals
2.Natural pants and microbial products
3.Drugs
4.others
Examples of organic chemicals
1.Benzene
2.Aromatic amines
3.Amides
4.Azo dues
5.Herbicides
6.Insecticides
Examples of natural plants and microbial products
1.Aflatoxin B1
2.griseofulvin
3.betel nuts
Examples of natural plants and microbial products
1.Aflatoxin B1
2.griseofulvin
3.betel nuts
Examples of drugs
1.Anticancer drugs
2.Immune suppressing drugs
Examples of other chemical carcinogens that cause cancer
1.vinyl chloride
2.Nickel
3.Chromium
4.Insecticides
What are the stages of chemical carcinogenesis
1.Initiation
2.promotion
3.progression
Characteristics of Initiated cells
Presence of unrepaired DNA damage
-they do not have growth autonomy or genotypic markers typical of cancer.Therefore the initiated cells are susceptible to promoters which induce proliferation
What are promoters
Irritants or substances that allows cell activation and proliferation
Are effects of promoters reversible
Yes
Instances where promoters cannot induce neoplasia
1.Alone
2.if applied before initiator
3.if applied in small amounts
4.if too much time taken between applications
What are pro-carcinogens
They require metabolic activation to become carcinogens
Examples of ionizing radiation
1.x rays
2.gamma rays
3.alpha,beta,positron,proton,neutron,primary cosmic radiation
What are the 2 mechanisms that may lead to mutations when exposed to radiation carcinogenesis
1.Direct interaction with DNA
2.Indirect damage mediated by free radicals generated from water or oxygen
What are the factors that correlates with mutagenicity of ionizing radiation
Radiation quality
Dose and dose rate
Efficiency of host DNA repair
Other factors like age, immune deficiency
What are the type of cancers that occur in fair skinned people
Squamous cell carcinoma
Basal cell carcinoma
Melano carcinoma
What are the factors that lead to mutations when exposed to uv rays
Pyrimidine dimer formation in DNA
Activation of T suppressor cells resulting in tumor clones
Individuals with defects in enzymes that mediate DNA excision repair
Human papillomavirus causes
Laryngeal papilloma
Squamous cell carcinoma of cervix
Epstein Barr virus (EBV) causes
Burkitt lymphoma
Nasopharyngeal carcinoma
Hepatitis B and Hepatitis C virus causes
Hepatocellular carcinoma
What are the DNA oncogenic viruses
Human papilloma virus
Epstein Barr virus
Hepatits B virus
Kaposi sarcoma herpes virus
RNA oncogenic virus
HTLV-1
What does HTLV-1 cause
adult T cell lymphoma
What are oncogenes
Genes that promote autonomous cell growth in cancer cells
How do oncogenes activate
1.balanced translocation
2.chromosomal translocation
3.point mutation
4.deletion
5.amplification
6.cytogenic manifestation of gene amplification
Ras gene?
An oncogene thats activated by a point mutation
What produces an activated tyrosine kinase
Translocation of chromosome 9 and 22 in chronic myelogenous leukemia creates a fusion gene
What are the oncogenes that are amplificated in neuroblastoma and breast cancer
N-myc
C-neu
What is the function of tumor suppressor genes
Regulate cell growth
Both alleles of the tumour suppressor gene must be inactivated by mutation for hyperproliferation to occur?
Yes
