More than Just Lines on a Map: Best Practices for U.S Bike Routes
What causes cancer?
1. What Causes Cancer?
Most, if not all cancers are caused and perpetuated by a small population of tumor-initiating cells
that exhibit numerous stem cell-like properties. Adult stem cells (SC) are involved in the
regeneration and maintenance of our body tissues and account for one out of every 6 million
cells. Each tissue has a unique population of specific SCs located in regions known as niches. In
the SC niche, the SCs exist in a unique dormant state known as quiescence, and remain in this
state until they are given the cues to be activated.
Activated stem cells go through two stages of development referred to as proliferation and
differentiation. During proliferation, biochemical cues cause the cells to reproduce, resulting in
an expanded population of similar cells. Differentiation puts a stop to proliferation with specific
biochemical cues that cause the proliferating cells to differentiate into a specific type of cell.
Once a stem cell has differentiated, it has a finite life span and is limited in how many times it
can reproduce. The number of times a differentiated cell can reproduce is referred to as its
Hayflick number.
Cancer results when a stem cell is stuck in proliferation, and is therefore not given the cues to
differentiate. This situation results in a continually expanding population of undifferentiated cells
that can not only exist anywhere in the body (metastasis), but also have unlimited life spans (no
Hayflick number).
The biochemical cues for proliferation and differentiation are based on genes specific to each
tissue type. In general, genes that initiate proliferation are called oncogenes while genes that
initiate differentiation are called tumor suppressors. Cancer, therefore, could be seen as an over-
activation of oncogenes accompanied by the inhibition of tumor suppressors. It is the ratio of
oncogenes to tumor suppressors that determines the aggressiveness of the cancer.
Another key piece in the growth of cancers is a process called angiogenesis. Angiogenesis is the
physiological process that tumors use in order to recruit new blood vessels in order to sustain
their continual growth. They do this by over-expressing genes that initiate and direct the growth
of new, leaky blood vessels from existing ones. Both angiogenesis and the spontaneous
formation of new blood vessels (vasculogenesis) are initiated by unique combinations of genes.
Standard chemotherapeutic agents inhibit rapidly dividing cells during treatment, but do not
affect dormant cancer initiating SCs. An example of this is shown in a side affect of treatment.
During chemotherapy, patients lose their hair (rapidly dividing cells), but their hair typically
grows back soon after treatment. This is due to the dormant SCs located in the hair shaft, which
were not affected by the chemotherapy. It is this presence of dormant cancer initiating SCs
combined with the occurrence of angiogenesis in-between treatment regimes that leads to disease
recurrence.
The following link allows you to access the genes involved with various types of cancers.
http://www.genome.jp/kegg/
Alex Rolland is a cancer researcher, educator, and CEO of Cancer treatment Options and
Management (www.CTOAM.com). CTOAM is a personalized cancer research company that
specializes in using the most current peer reviewed scientific research on cancer diagnostics,
treatments, nutraceuticals, and clinical trials to educate patients on the treatments and diets that
provide the best statistical chances for success.