The Dangers of HPV

By Emma and Cassie

What is HPV?

HPV is an abbreviation for human papillomavirus. HPV infection occurs when the virus enters through a cut in the skin. The virus is transferred primarily by skin-to-skin contact. It is the most commonly sexually transmitted virus in the US.

What is oral HPV?

Oral HPV is found in the mouth and throat. It can cause cancers in the head and neck. It can also lead to warts in the throat and mouth.

Is it curable?

NO! HPV is not curable but the symptoms can be treated by a general physician.

What are the symptoms?

Symptoms of HPV are genital warts, cervical cancer, and other cancers. Genital warts appear as a group of small bumps in the genital area. Cervical cancer does not usually show symptoms until it has become more developed, which causes it to be very difficult to treat later on.

How is HPV spread?

HPV is spread by skin to skin contact, such as handshakes. It can also be transmitted to a baby by the mother during pregnancy, labor, or nursing.

What HPV proteins cause cancer?

- HPV produces the proteins E6 and E7 which shut down two important tumor suppressor proteins in normal cells. It causes p53 and Rb to deactivate and allow cells to grow out of control.

- E1 and E2 are required for DNA replication. E2 makes sure viral DNA moves into new cells during mitosis and acts as a transcriptional activator or repressor. E2 controls other E genes such as E6 and E7. As E2 increases, E6 and E7 are down regulated. This ends up in a loss of the cellular environment needed for viral DNA replication. This change in the gene expression produces more of the HPV virus. When the infected cells reach terminal differentiation its causes the genes L1 and L2 to be expressed. L1 and L2 are proteins that are produced in the second or last phase of the viral life cycle.

- HPV types 16 and 18 are responsible for the majority of HPV-caused cancers. Type 16 and 18 are responsible for about 70 percent of all cervical cancer cases. A study on HPV 16 in the US shows the amount of HPV 16 is higher in women compared to men. Most of the time in women, the infection is only temporary, but in a minority of women the HPV virus will persist. If the HPV type is 16 or 18 there is an increased risk of developing cervical cancer.

What kinds of cancers can HPV cause?

- HPV can cause many types of cancer such as cervical cancer. Cervical cancer is caused when a woman comes in contact with HPV. Her immune system usually fights off the virus and prevents it from doing serious harm. In some women the virus survives and eventually leads to the conversion of normal cells to cancerous cells in the cervix.

- HPV can also cause cancers of the vulva, vagina, penis, anus, and oropharynx (back of the throat)

How does HPV affect the cell cycle?

A big part of a normal cell cycle is regulated by 2 protein, p53 and Rb. Rb separates the transcription factors that are necessary to progress through the cell cycle. Rb prevents the cell from dividing before it is ready. Rb segregates the E2F protein, which makes it a tumor suppressor gene. it doesnt allow the cell cycle to continue until it has accumulated enough if the E2F. When a cell is infected with HPV, the E7 gene binds to Rb which causes it t produce E2F and other proteins. This is the signal for the cell cycle to continue. As long as E7 stays attached to Rb, the cell cycle will continue. This causes the cell to grow uncontrollably.