Lapatinib: Difference between revisions

[[EGFR|Epidermal Growth Factor Receptors]] are overexpressed in many types of human [[Cancer|carcinomas]] including lung, pancreatic, and breast cancer, and are often mutated. This overexpression leads to excessive activation of the anti-apoptotic [[Ras]] signalling cascade, resulting in uncontrolled [[DNA_Replication|DNA synthesis]] and cell proliferation. Studies have revealed that the <scene name='Lapatinib/Egfr/1'>EGFR tyrosine kinase domain</scene> is responsible for activating this Ras signaling cascade. Upon binding ligands like Epidermal Growth Factor, EGFR dimerizes and autophosphorylates several tyrosine residues at its C-terminal domain. Upon phosphorylation, EGFR undergoes a significant conformational shift, revealing an additional binding site capable of binding and activating downstream signaling proteins.<ref>PMID:6090945</ref><ref>PMID:16729045</ref> Erlotinib inhibits the EGFR tyrosine kinase by <scene name='Lapatinib/Egfbb/1'>binding to the ATP-binding site</scene> located within the kinase domain. Residues Met 774, Leu 825, Val 707, Thr 835, Asp 836, Phe 837, Thr 771, Lys 726, Ala 724, & Leu 769 tightly bind the inhibitor in place. Unable to bind ATP, EGFR is incapable of autophosphorylating its C-terminal tyrosines, and the uncontrolled cell-proliferation signal is terminated.<ref>PMID:15284455</ref><ref>PMID:15374980</ref>

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