The Cellular Basis of Cancer
Despite recent understanding in the steps involve in metastasis process, the constant return of metastasises remains the greatest barrier in the development of treatment for cancer.
The DNA contained in all life on Earth must constantly deal with attack by agents which can directly damage the genes located in the DNA. Failure to follow the sequences of events involved in the cell cycle can be the start of cancer. The cell cycle is often considered to be composed of four stages: the phase before DNA replication (G1), the phase where the DNA is synthetic (S), the stage after DNA replication (G2) and the mitotic phase which terminate the cell division (M) (Hartwell & Weinert 1989). The term ‘cell-cycle checkpoint’ refers to the mechanisms which the cells adopt in order to regulate the progress through the cell cycle, making sure that each step is in the right order, only occurs once and there is no damage done to the DNA of the cells. There are two checkpoints which are specifically sensitive to DNA damage, the first checkpoint is located in the transition stage of G1/S, where most genetic fault related to cancer occur and the second checkpoint will be located at the G2/M stage where it will