Genetic Mechanism of Cancer and Anticancer Drug Development

What is Cancer?

Cancer is a disease of cell where the cell grow abnormally, continuously and relentlessly. The excess cell thus produce a tumor  which in time split off, some of these cell spreading to other parts of the body or organ where they produce secondary cancer and ultimately cause the vital organ dysfunction or damage  and consequently cause death.

Carcinogenesis:

Carcinogenesis is a sequential process involving Initiation, Promotion (Pre-malignancy), Progression (Malignancy and Metastasis) which are primarily induced as a result of exposure to carcinogens.

The major carcinogens that cause cancers are-

-Chemicals (soft drinks, organic solvent, fast food)

-Radiation (Sun bath, X-ray)

-Viruses

Genetic mechanism of cancer:

              Chemical carcinogens such as those in tobacco, azo-dyes, aflatoxins, benzene are clearly implicated to cancer induction in human and animals.

                Certain herpes and papilloma group DNA and type C RNA viruses have also been implicated as causative agent in animal as well as human cancers.

                 Oncogenic RNA viruses contain a ‘reverse transcriptase’ enzyme that permits translation of the RNA message of tumor virus into the DNA code of the infected cells.

A specific human T-cell leukemia virus (HTLV-1) related to HIV-1 is the causative agent for this type of leukemia.

Development of Cancer:

Cancers develop as a consequence of multiple changes which activate oncogenes and inactivate tumor suppressor genes. Each human cell contains tens of thousands of genes and a few proto-oncogenes that may be responsible for cell proliferation. On exposure to carcinogenic influences, one or more of the proto-oncogenes activate oncogenes. Cells carrying these activated oncogenes become cancerous. Vital oncogenes are introduced into human cells by virus to the development of cancers.

                  Absence or inactivation of anti-oncogenes or tumor suppressor genes can also contribute to the development of cancer.

Anticancer drug development:

1.      During the last 4 decades anticancer drug are developed by screening   and rational design of new compounds.

2.      By synthesis   of peptide and protein with recombinant DNA techniques.

3.      Attempt has been taken to produces monoclonal antibodies.

4.      Target of these anticancer drug is to remove all most all of the cancer cell from the body .But none of the currently used anticancer agent is capable to remove all of the cancer cell. That’s why, combination therapy is used to make success of anticancer treatment. Even having so many attempt, none of these therapy is successful, if the cancer is in metastatic state.   

Combination therapy are of 4 types. They are-

1.      Surgery

2.      Chemotherapy

3.      Radiotherapy

4.      Biotherapy