Monday, August 6, 2012

Chemotherapy can sometimes increase cancer growth

Therapies for cancer are never very pretty. Scientists struggle with creating treatments that specifically target cancerous cells and leave healthy tissue alone. Radiation therapy, for example, can be targeted directly onto a tumour, but surrounding tissue suffers from it as well. Chemotherapy is another example: basically, it is poison that just kills malicious cells a bit faster than healthy cells. However, a recent study shows that chemotherapy can actually increase growth of tumour cells. Disturbing, but knowing the mechanism helps us to improve therapies.

A study conducted by American scientists focused on discovering mechanisms behind tumour resistance against chemotherapy. A nasty characteristic of certain cancers is that they, during the therapy, develop resistance that renders them immune. In order to discover which factors govern this particular resistance, the scientists scanned the DNA for changes that arise due to chemotherapy.

After their analysis, the scientists found that a protein of the 'Wingless' family plays an important role in the development of resistance. Wingless, or Wnt, plays an important role in embryonic development, but is pretty much omnipresent. The subtype Wnt16B was found to be involved with resistance, and even showed to increase tumour growth in cells that possess it.

Wnt16B may explain why tumours regrow after a round of chemotherapy. Cells expressing this protein survive, and even manage to expand due to the treatment. After a while, all the 'normal' cancer cells are dead, and the Wnt16B-positive cells are able to grow freely. This would explain the 'rebound' effect sometimes observed in treatment. Enhancing conventional chemotherapy with an inhibitor for Wnt16B could reduce resistance and keep a tumour down without rebounding in growth.

Cocurrent treatment
Cancer therapy often consists of a cocktail of drugs, and not just chemotherapy. There are a lot of novel treatments in development, such as combining chemotherapeutics with a beehive extract. Another interesting example is a treatment strategy where conventional means are combined with targeting receptors that are normally involved with drug abuse.

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