Virus and Cancer

Viruses are usually not complete carcinogens in human cancers

Tumor viruses establish chronic infections in humans

Cancer is an accidental side of viral replication strategy

Oncogenes: These are stimulatory for growth, cause cancer when hyperactive.

Tumor-suppressor genes: genes that inhibit cell growth and cause cancer when turned off.

Two classes of genes

Virus can either carry a copy of one of these genes or can alter expression of the cell’s copy.

How do Virus get involved?

Non-living particleConsisting of proteins and nucleic acid, either DNA or RNA at its core

What is a virus?

A Virus

Can not replicate on its own, uses host machinery to replicate.

Entrance is gained through receptors on the cells.

Once inside, viral RNA is reverse read to make a segment of DNA

RNA

Reverse Transcriptase

Viral Replication

http://schoolworkhelper.net/viral-replication-lytic-cycle/

4 steps1. Attachment and entrance2. Synthesis of proteins3. Assembly of new virus4. Release of new virus particles (lytic or lysis)

DNA Tumor viruses2 life styles◦ A permissive cell: all viral parts are replicated◦ Lysis and death of cell

◦ A non-permissive cell: DNA integrated into the cell chromosome randomly.

◦ Only parts are expressed ◦ No progeny released.

Virus to Cancer

Hepatitus C Cervical Cancer

How the virus works in two disorders

10

P53 (tumor suppressor)P53 (tumor suppressor)

P53 gene P53 gene P53 gene

P53

P53 DNA

Stops replication

Hepatitis C

P53

replication replication

Papilloma proteolysis

P53

Papilloma

Viral proteins interact with p53 and lead to cell proliferation and prevents apoptosis

Transfers by blood

Liver damage, such as cirrhosis, or scarring of the liver

Liver failure Need for a liver transplant Liver cancer Death

Hepatitus C

DNA Virus8 kilobases long>100 types of HPVCause warts – benign

Malignant carcinomasepidermodysplasia verruciformis

•Autosomal recessive mutation •leads to abnormal uncontrolled virus replication.

•Penile, uterine, cervical, canal carcinomas

Human Papillomavirus

http://www.ansci.wisc.edu/jjp1/ansci_repro/misc/project_websites_07/tue07/HPV_Vaccine/What%20is%20HPV.html

HPV

New cases 2012 US: 12,170 Deaths: 4,220 average age at death 57 yrs Incidence rate:

◦ 8.1 per 100,000 women◦ Hispanics 11.8 per 100,000 women◦ Lifetime Risk for women born today- 1 in 147.

All statistics from the National Cancer Institute, Surveillance Epidemiology and End Results.

Cervical Cancer

Symptoms

Diagnosis

Precancerous lesions Cryosurgery (freezing) Leep- loop electrosurgical excision

procedure. Laser vaporization

Cancerous tissue Surgery Radiation Chemotherapy

Treatment

From the U of Rochester HPV Vaccine Protects against 4 types of HPV

◦ “2 types of HPV that cause about 75% of cervical cancer cases, and 2 more types that cause 90% of genital warts cases. In boys and young men ages 9 to 26, GARDASIL helps protect against 90% of genital warts cases”

(Guardacil.com)

New Treatment: Guardacil

How a vaccine works

Penn Medicine, University of Pennsylvania Immunotherapy program Personalizing approach that boosts the

bodies own immune system to attach tumors.

Using the patients own tumor proteins in a vaccine.

Cutting edge research

http://www.uphs.upenn.edu/obgyn/research/ovarian_clinical.htm

Virus can show up in the DNA of a host, damaging the cell cycle, causing uncontrolled growth of a cell.

Virus that are carcinogenic are passed in body fluids.

Be safe. Consider a vaccine to help prevent cervical

cancer.

Conclusion

Hunt, R. 2009. Microbiology and Immunology on-line, University of South Carolina School of Medicine. http://pathmicro.med.sc.edu/lecture/retro.htm

Howlader N, Noone AM, Krapcho M, Neyman N, Aminou R, Altekruse SF, Kosary CL, Ruhl J, Tatalovich Z, Cho H, Mariotto A, Eisner MP, Lewis DR, Chen HS, Feuer EJ, Cronin KA (eds). SEER Cancer Statistics Review, 1975-2009 (Vintage 2009 Populations), National Cancer Institute. Bethesda, MD

National cancer institute. National institute of health. http://www.cancer.gov/cancertopics/pdq/treatment/cervical/Patient/page2

Ovarian Research. Penn Medicine, University of Pennsylvania. Available at http://www.uphs.upenn.edu/obgyn/research/ovarian_clinical.htm

References