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Leptin and Metastasis

Jan 7, 2011 | By Jeffery Herman
Leptin and Metastasis
Photo Credit fat belly and beer image by Cherry-Merry from Fotolia.com

Leptin is a naturally occurring hormone that is expressed at high levels in fat tissue. At its discovery leptin was viewed as a possible cure for obesity. According to the 2010 issue of "Respiratory Research," Dr. Foteini Malli described how decreased leptin activity in mice caused increased body weight and increased levels of various disorders commonly associated with obesity. Leptin is expressed in various organs throughout the body with important roles in numerous processes including cancer development, progression and metastasis.

Proteolytic Enzymes

The extracellular matrix, or ECM, is essential for organ and tissue integrity. Specialized proteolytic enzymes -- proteins that are produced in the cell which degrade the ECM -- often are over-expressed in cancer. A high expression of these proteolytic proteins allows tumor cells to invade and alter the integrity of adjacent tissue. According to Dr, Vanity McMurty in the 2008 issue of "Clinical and Experimental Metastasis," Leptin can increase expression of these proteolytic enzymes, which is often an important initial step in metastasis.

Leptin And Cell Migration

Cellular migration is an important process that regulates the immune response and wound healing. Cancer cells will often exploit this process in order to invade and metastasize into adjacent or distant tissue, respectively. Migration is largely regulated by hormones and other extracellular proteins. In laboratory experiments, leptin increases migration of colon cancer cells. In prostate cancer cells, leptin enhanced the effect of other migratory regulating proteins.

Cancer Invasion

Invasion occurs by the separation of tumor cells from the primary tumor and their entrance into the surrounding tissue. This process is often the first sign of a more advanced and aggressive cancer. According to Kerstin Lang, in the 2009 issue of "Cell Communication and Signaling," leptin can successfully promote invasion of aggressive human prostate cancer and colon cancer cell lines. According to Dr, Vanity McMurty in the 2008 issue of "Clinical and Experimental Metastasis," leptin can also increase invasion of human breast cancer cells.

Cancer Metastasis

Cancer metastasis is the last stage of an aggressive tumor. Metastasis occurs when tumor cells invade into the blood stream, reach distant organ sites in the body and form secondary tumors. These secondary tumors destroy normal organ function and are usually the cause of a patient's death. Leptin is a promoter of metastasis. For example, according Dr. Kersten Lang in the 2009 issue of "Cell Communication Signaling," a 34 percent increase in breast cancer metastasis was observed in breast cancer tissue with higher leptin levels.

Contradictory Reports

As is the case with most scientific discoveries, there is contradictory evidence of leptin's role in metastasis. For example, according Dr. Kersten Lang in the 2009 issue of "Cell Communication Signaling," certain leptin experiments actually blocked invasion and migration of prostate cancer, rather than promoting it. According to the 2008 issue of the "Annals of Surgical Oncology," Dr. Seung Sam Paik found that high leptin expression correlated with less aggressive colon cancer, a strict contradiction to other reports. These differences could be due to a variety of reasons, including experimental error.

References

Article reviewed by Billie Jo Jannen Last updated on: Jan 7, 2011

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