Question

Tumors (and cancer cells) are cells that replicate uncontrollably. Why would it benefit a provirus to convert a normal animal cell into a tumor cell?

Answer 1

Cancerous cells are cells that were previously normal cells. Due to some mutations, the normal cells turn abnormal in structure and function and gets referred to as cancer cells. The abnormality of these cancer cells lies in their malignancy. These cells also undergo metastasis, ie they are not assigned to one single area. They keep travelling and invade other tissues and body parts.

The provirus is also referred to as Prophages. They are viruses which are a part of the host cell's DNA. Retroviruses such as the HTLV is an example of provirus that cause normal cells to get converted into cancerous cells. These viruses undergo a molecular mechanism of tumor induction. The proviral integration sites of the provirus are not specific in nature. It basically can affect any cellular gene by integrating itself into it. This insertion can inactivate the host gene. It can also alter the regulatory signals of the host gene. Now the provirus after successfully integrating the host gene alters its functions. This function alteration causes the cell to become cancerous in nature. As we know cancer cells undergo uncontrolled division, the affected host gene also undergoes the same. This helps the virus in replicating its own self causing its own benefit.