Cancer cell

This article is about cancer cells. For the scientific journal, see Cancer Cell (journal).

Scanning electron microscopy image of a lymphocyte

A diagram illustrating the distinction between cancer stem cell targeted and conventional cancer therapies

Cancer cells are cells that grow and divide at a rapid and unregulated pace. Although cancer cells are regularly created in the body, the disease known as cancer only occurs when immune cells (particularly natural killer cells) fail to recognize and/or destroy them. In the past a common belief was that cancer cells failed to be recognized and destroyed because of a weakness in the immune system. However more recent research has shown that the failure to recognize cancer cells is caused by the lack of particular co-stimulated molecules that aid in the way antigens react with lymphocytes.

Causes

Stem cell research suggests that too much SP2 protein may turn stem cells into cancer cells. Other issues thought to play a role in the spread of cancer include viruses, immune system issues, genetics, environment and age. However, a lack of particular co-stimulated molecules that aid in the way antigens react with lymphocytes can impair the natural killer cells' function, ultimately leading to cancer.

Cancer cells are created when the genes responsible for regulating cell division are damaged. Damage to DNA (mutations) can be caused by exposure to radiation, chemicals, and other environmental sources, but mutations also accumulate naturally over time through uncorrected errors in DNA transcription, making age another risk factor. This may eventually result in the rapid, uncontrolled growth characteristic of cancer cells.

Pathology

White Blood cells are thought to use a dual receptor system when they determine whether or not to kill human cells. If a cell is under stress, turning into tumors, or infected, molecules including MIC-A and MIC-B are produced to put on the surface of the cell. These work to detect and kill cancer cells.

Discovery

Some descriptions of cancer, not all descriptions, go back to ancient Egypt as far back as 1600 BCE and the understanding of cancer was significantly advanced during the Renaissance period. However, Sir Rudolf Virchow, a German biologist and politician, is generally credited with discovering the first cancer cells. As Giovanni Morgagni had linked autopsy findings seen with the unaided eye with the clinical course of illness, so Virchow correlated microscopic pathology.

Telomerase

Cancer cells have unique features that make them "immortal" according to some researchers. The enzyme telomerase is used to extend the cancer cell's life span. While the telomeres of most cells shortens after each division eventually causing the cell to die, telomerase extends the cell's telomeres. This is a major reason that cancer cells can accumulate over time creating tumors.

Cancer stem cells and drug resistance

Scientists have discovered a molecule on the surface of tumors that appears to promote drug resistance—by converting the tumor cells back into a stem cell-like state. When the tumor cells began to exhibit drug resistance, the cells were simultaneously transforming into a stem cell-like state, which made them impervious to the drugs. It appeared that the treatment itself was driving this transformation by activating a specific molecular pathway. Luckily, several existing drugs can attack this pathway and reverse the cellular transformation, thus ‘re-sensitizing’ the tumor to treatment.

See also

• Apoptosis
• BRCA1
• Carcinogen
• Carcinogenesis
• Epidemiology of cancer
• Oncology

External links

• BCG strain S4-Jena: An early BCG strain is capable to reduce the proliferation of bladder cancer cells by induction of apoptosis. Ncbi.nlm.nih.gov. Retrieved on 2010-12-01.
• The History of Cancer. Cancer.org. Retrieved on 2010-12-01