FIGHTING CANCER

CANCER IMMUNOTHERAPY

Understanding how good bacteria interact with the immune system helps find ways to use these good bacteria as therapies against infections, autoimmune diseases, and cancer.

You have 500 kinds of good bacteria known as commensals in your intestines.  They help good digestion.  The immune system does not attack them even though they are bacteria.  You have more bacteria than you have human cells.  Targeting these good bacteria may be a way to treat against infections and give you more immunity.

These good bacteria, commensals, protect you from the harmful bacteria called pathogens.  The body must get rid of bad bacteria and it relies on its immune system to tell bad bacteria from good bacteria.

Cancer cells are tumorgenic independent of their local environment by acquiring genetic and epigenetic changes.  Their neighbors may permit and even nourish the growth of transformed cells.  These tumorgenic cells secrete signals that change the surrounding tissues.

Immune cells from the intestines bind to the good commensal bacteria whenever a pathogen is present.  When bound, protective T cells are increased and they destroy the invading bad bacteria pathogen.  During an infection, the immune regulating cells send signals to get the commensals into action.

Occasionally, an immune response to comensals can cause problems. Inflammatory bowel diseases as Crohn’s disease are cause by immune reactions against the good commensal bacteria.

It is critical to enlist the immune system to fight tumors.  Today most cancer vaccines are not to prevent cancers but merely designed to treat serious existing cancers.  

Theory by Olivera Finn, past president of the Am. Assoc of Immunologists, thinks that infections throughout life, including chicken pox and other childhood diseases may prime our defenses to prevent cancers.  She found donated organs were rejected because of only one or two antigens.  Cancer cells can rouse the immune system.  Does the immune system thwart early cancers or is it too feeble to stop these cancers?

 It’s hard to find cancer antigens.  Can a tumor antigen be used as a vaccine to prevent cancer?  The first cancer antigen was a protein called MUC1 that comes from pancreatic and breast cancer cells.  It is also found in normal cells in several organs, so why don’t these T cells pounce on cancers?   It seems tumor antigens differ from the non-tumor antigens found in normal cells by their structure, quantity, or cellular location.

Cyclin B1, another cancer antigen, helps propel cells through mitosis.  It can act as a tumor antigen because of sheer quantity.    The amount of antigen is low in normal cells.  Yet cancer cells churn the tumor cancer antigen protein continuously.

 Many of us get natural vaccinations against cancer from unexpected pathogen sources.  A variety of invaders, including those causing childhood disease spur the production of the same abnormal self-antigen as it does from cancer cells.

 The chickenpox virus sparks an explosion of cyclinB1.  The mumps virus displays denuded MUC1.  Getting sick as a kid when your immunity is high can give you full immunity. This may spare you from cancer in later years.

People with active infections carry antibodies to MUC1, and show a high  immune response.   Can we soon focus on developing preventive cancer vaccines?    Only the FDA and drug companies have the answer!

Sources: Science Aug. 15, 2008, ScienceDaily   (Oct 4,2008), and Cell 135, 437,2008

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