Quantum mechanics

Cell biology

Biology

Osteoclast

Endocrinology

Receptor

Cancer research

Biochemistry

Bone resorption

Physics

Mechanism of action

Anatomy

Mevalonate pathway

In vitro

Biosynthesis

Enzyme

Prenylation

Pharmacology

Skeleton (computer programming)

Medicine

Chemistry

Action (physics)

Osteoporosis

Bone

Bisphosphonates (BP) are a class of calcium-binding drug used to prevent bone resorption in skeletal disorders such as osteoporosis and metastatic bone disease. They act by selectively targeting bone-resorbing osteoclasts and can be grouped into two classes depending on their intracellular mechanisms of action. Simple BPs cause osteoclast apoptosis after cytoplasmic conversion into toxic ATP analogues. In contrast, nitrogen-containing BPs potently inhibit FPP synthase, an enzyme of the mevalonate (cholesterol biosynthesis) pathway. This results in production of a toxic metabolite (ApppI) and the loss of long-chain isoprenoid lipids required for protein prenylation, a process necessary for the function of small GTPase proteins essential for the survival and activity of osteoclasts. In this review we provide a state-of-the-art overview of these mechanisms of action and a historical perspective of how they were discovered. Finally, we challenge the long-held dogma that BPs act only in the skeleton and highlight recent studies that reveal insights into hitherto unknown effects on tumour-associated and tissue-resident macrophages.

Molecular mechanisms of action of bisphosphonates and new insights into their effects outside the skeleton