
Tetracycline, Doxycycline, and Minocycline are three members of the tetracycline family.  Tetracyclines are used as antibiotics, and their patents have long expired, so they are available cheaply as generics.  Because the medication is generic and cheap, there's less financial incentive for drug companies to fund research.

Tetracyclines migrate to and are absorbed by bone.  

In order for metastases to grow in bone, the structure of the bone must be dissolved.  Either osteoclasts or cancer cells secrete matrix metalloproteinases [MMPs] [enzymes that help break bone structure down.]  Tetracyclines inhibit "matrix metalloproteinases", by combining with a Zinc ion at the active site on the MMP.

Additionally, Tetracyclines have shown cytostatic and cytotoxic activity  against cell lines of various tumor origins. 

Doxycycline was able to inhibit the activity of 72- and 92-kDa type IV collagenase secreted by bone-metastasizing cells by 79-87%. These characteristics could make tetracycline a unique candidate as a  therapeutic agent to prevent bone metastases in cancer patients who have a high likelihood of developing bone metastasis.

Éxperimental evidence showing that doxycycline reduces tumor burden in a mouse model of breast cancer-derived osteolytic bone metastasis. This effect is likely due to a combination of multiple roles of doxycycline, including MMP inhibition and a negative effect on osteoclast differentiation and survival. These encouraging results have now paved the way for an ongoing trial of doxycycline in early combination therapy for breast cancer and prostate cancer patients.

Col-3, a chemically modified tetracycline, is now the subject of clinical trials in cancer patients. 


Search Pubmed for &&url 

1. Anti-Cancer Drugs 2003; 14(10):773-778 
<b>Doxycycline and other tetracyclines in the treatment of bone metastasis</b> 
Zeina Saikali, Gurmit Singh 

2. Invasion Metastasis 1997;17(6):312-22 Related Articles, Links  
<b>Use of tetracycline as an inhibitor of matrix metalloproteinase activity secreted by human bone-metastasizing cancer cells.</b>
Duivenvoorden WC, Hirte HW, Singh G.
&&url PMID: 9949290



compiled/written by doctordee
with thanks to Lynette and Laura 
June 2002 
updated December 2003
