The mevalonate pathway (also known as the cholesterol biosynthesis pathway) plays a crucial metabolic role in normal cell function as well as in the pathological environment. It leads to the synthesis of sterol and non-sterol isoprenoid biomolecules which subserve a variety of cellular functions. It is known to be deregulated in many disease processes. Statins and bisphosphonates are prominent inhibitors of the mevalonate pathway. They inhibit cell proliferation and activate apoptotic signalling and suppress tumour growth. Statins subdue metastatic spread of tumours by virtue of their ability to suppress invasion and angiogenesis. The induction of autophagy is another feature of statin effects that could contribute to the suppression of metastasis. Herein highlighted are the major signalling systems that statins engage to generate these biological effects. Statins can constrain tumour growth by influencing the expression and function of growth factor and receptor systems. They may suppress epithelial mesenchymal transition with resultant inhibition of cell survival signalling, together with the inhibition of cancer stem cell generation, and their maintenance and expansion. They can suppress ER (oestrogen receptor)-α in breast cancer cells. Statins have been implicated in the activation of the serine/threonine protein kinase AMPK (5' adenosine monophosphate-activated protein) leading to the suppression of cell proliferation. Both statins and bisphosphonates can suppress angiogenic signalling by HIF (hypoxia- inducible factor)-1/eNOS (endothelial nitric oxide synthase) and VEGF (vascular endothelial growth factor)/VEGFR (VEGF receptor). Statins have been linked with improvements in disease prognosis. Also attributed to them is the ability of cancer prevention and reduction of risk of some forms of cancer. The wide spectrum of cancer associated events which these mevalonate inhibitors appear to influence would suggest a conceivable role for them in cancer management. However, much deliberation is warranted in the design and planning of clinical trials, their scope and definition of endpoints, modes risk assessment and the accrual of benefits.
Keywords: Angiogenesis, apoptosis, cell proliferation, autophagy, cancer stem cells, cancer prevention, clinical benefits, epithelial mesenchymal transition, invasion and metastasis, mevalonate pathway, pharmacology of statins and bisphosphonates, statin signalling systems.