This morning I read some of the PubMed Alerts that I received during my absence. One of them led me to the abstract (see: http://tinyurl.com/5wrw5p) of a recent study on quercetin and prostate cancer cells published in “Prostate” at the end of August.
The researchers wanted to evaluate the effect(s) of quercetin on normal and malignant prostate cells and to identify the target(s) of quercetin’s action. Their results have implications for myeloma, too, as we will see later on: Our findings demonstrate that quercetin treatment of prostate cancer cells results in decreased cell proliferation and viability. Furthermore, we demonstrate that quercetin promotes cancer cell apoptosis by down-regulating the levels of heat shock protein (Hsp) 90.
Quercetin killed the malignant cancer cells by inhibiting this thingie called Hsp90, but did no harm to the normal prostate cells.
As their name suggests, heat shock proteins protect cells that are exposed to dangerously high temperatures. They are also triggered when, for instance, our cells are exposed to infections or toxins (etc.). But, and there is a BUT!, they can also be essential to the survival of cancer cells. You can read more about this process in Wikipedia: http://en.wikipedia.org/wiki/Hsp90 (scroll down to “Cancerous cells”). Inhibition of Hsp90 has thus become an important area in cancer research.
The main reason I am reporting about Hsp90 is that I found that it is a target of conventional myeloma treatment as well. I located several studies on the involvement of Hsp90 in the survival of myeloma cells, such as this one, published in August 2008 in “Leukemia”: http://tinyurl.com/59k4g8. It confirms that this particular heat shock protein is over-expressed in myeloma cells and critically contributes to tumour cell survival. Definitely not good!
A pertinent aside: a quick search of the Clinical Trial website revealed that there are currently three clinical trials involving multiple myeloma and two different Hsp90 inhibitors in combination with Bortezomib (Velcade). Two of the trials are still recruiting, the other is active but not recruiting. Interesting.
In conclusion, our (Sherlock’s and mine) most recent experiment did not include any quercetin, but I had already planned to resume taking it after the summer holiday. And so, last week, I added one gram of quercetin to my regular protocol.
After reading the Hsp90/quercetin abstract this morning, I am very happy I did so!