Chemo agents acting on Structural Proteins

Question 1

Give examples of a microtubule targetting drugs

Answer 1

Vinca Alkaloids (Vincristine, vinblastine)
Taxanes (Paclitaxel, Docetaxel)
Colchicine

Question 2

What is the moa of vinka alkaloids

Answer 2

• They are microtubule destabilising agents
• block tubulin polymerisation by binding at the interface of 2 tubulin heterodimers and inhibiting the uptake of GTP
• which is essential for microtubule elongation
• meaning the mitotic spindle cannot be formed
• promoting chromosome dumping
• prevents cell from undergoing mitosis
• cells cannot replicate

Question 3

what is the moa of Taxanes (Paclitaxel)

Answer 3

• Microtubule destabilising agents
• They promote microtubule polymerisation
• this stabilisation means the mitotic spindle does NOT breakdown
• and cells are arrested in mitosis
• cells cannot replicate

Question 4

What is the moa of Colchicine

Answer 4

• binds to colchicine binding site on B tubulin

- same moa as taxanes

Question 5

What are the disadvantages of colchicine?

Answer 5

Emetic

Teratogenic

Question 6

What is the moa of Estramustine

Answer 6

• binds to microtubule associated protein 4 (MAP-4)
• causes dissociation of protein from microtubule via hydrolysis
• causes depolymerisation and disassembly