HPV and cervical cancer

Cervical cancer = HPV infection

Cervical cancer is the second most deadly cancer in women worldwide, namely squamous cell carcinoma and adenocarcinoma. In 100% of isolated cervical cancer cells (from pap smears), the DNA from human papilioma virus (HPV) is present. This means the only way acquire cervical cancer through HPV infection! source

A virus that causes cancer?

HPV upon infection, attaches to the cells of your cervix, and inserts its own DNA. This viral DNA then integrates itself between your cells' DNA. The cellular processing machinery (which normally reads your DNA and makes human proteins) instead reads the new DNA code (now a different code than before because its now a mix of viral and human DNA) and acts accordingly. This code instruct your cells to make and secrete viral proteins (the building blocks of more viruses). The cell eventually becomes (for lack of better wording) "filled" with new viruses until the cell bursts and the new viruses go off to infect more cells, and the cycle repeats.

Image of virus attaching to cell membrane and inserting its DNA 

1. Virus attaches to cell and injects DNA

2. Viral DNA integrates into cell's DNA. Cell dies and viral machinery takes over.

3. New DNA code instructs cells to make viral proteins 

4. and 5. New viruses are assembled

5. Cell bursts and new viruses infect more healthy cells 

The problem? Conventional anti-vrial medications possessing ability to reduce viral titers (or amounts) to a level more manageable for your immune system to fight, are not helpful. This is because the particular way the viral genes are inserted into your DNA produces a 'code' that destroys your cells tumor suppressor genes. Tumor suppressor genes are as they sound, think of them as cancer fighting genes.

Here's how it goes: You have several genes (known as tumor suppressors) that prevent healthy cells from becoming cancerous. When these tumor suppressor genes are mutated, they no longer protect the cell. In the case of HPV, the viral DNA integrates itself into your cell's DNA and in doing so, mutates a tumor suppressor gene. This particular tumor suppressor (called p53) is responsible for halting a cell's cell cycle or division when it becomes cancerous. Remember, cancer is the uncontrolled division of cells so if there is no longer a way to arrest (aka stop and kill) cancerous cells they continue to divide and divide. Another tumor suppressor (retinoblastoma) is also degraded which serves to keep healthy cells from growing too fast.

(Recap)

1. HPV + healthy cell = Cell with mixture of viral/human DNA

2. New DNA signals cells to make viral proteins

3. Viral proteins degrade important tumor suppressor genes

4. No tumor supressor genes --> no restriction on cell growth --> uncontrollable cell growth --> cancer

Scary Statistics

According to the CDC, nearly 6.2 million people are infected with HPV each year and of those, nearly 20% of women will develop cervical cancer or cancer lesions. This means, if you are infected and don't seek treatment (generally a surgical or lazer intervention) you have a 20% chance of developing cervical cancer. Get to your OBGYN and get a pap screening people!!!!!!!! 

Early detection!

Now before you get completely frightened, know this: with early intervention, the chance of a cancerous lesion progressing to full-blown cervical cancer is low. Yearly pap-smears can reduce the chance of developing cervical cancer by 80%!

(Recap) 

HPV infection + no treatment = 20% chance of cervical cancer

HPV infection + early detection = 20% chance x 80% reduction = 4% chance

* Stay tuned for Post II: Cervical cancer and HPV vaccines