Problems preventing successful cell division?

Question

What are a list of potential problems that may occur to prevent successful cell division? (What might stop it or lead it to tumor or cancer) How can this be manipulated and used as a cancer treatment?

Answer 1

The question isn't entirely clear and there is an endless list of potentially problems, but I think you are looking for replication checkpoints which ensure proper replication of DNA for cell division. Anytime DNA is damaged by either exogenous sources (UV light, ionizing radiation, mutagens) or endogenous sources (Reactive Oxygen Species, Replication errors) it activates pathways that slow the cell cycle down to allow time for repair. Mutations in checkpoint control proteins (p53, pRB) are the most commonly found mutations in cancers since when you lose checkpoint control it allows for damaged DNA to be passed on during cell division.
Mutations in DNA damage repair proteins can also lead to cancer. Also very common in many types of cancer.
The reason these mutations can be exploited for therapeutic advantage is the simple fact that they are more susceptible to DNA damage caused by many chemotherapeutics. Normal cells will repair damage caused by a specific drug while many cancer cells lack the proper response and end up dying.

Hope that helps.