Growth Inhibition by Bupivacaine Is Associated with Inactivation of Ribosomal Protein S6 Kinase 1

Abstract

Bupivacaine is an amide type long acting local anesthetic used for epidural anesthesia and nerve blockade in patients. Use of bupivacaine is associated with severe cytotoxicity and apoptosis along with inhibition of cell growth and proliferation. Although inhibition of Erk, Akt, and AMPK seemingly appears to mediate some of the bupivacaine effects, potential downstream targets that mediate its effect remain unknown. S6 kinase 1 is a common downstream effector of several growth regulatory pathways involved in cell growth and proliferation known to be affected by bupivacaine. We have accordingly attempted to relate the growth inhibitory effects of bupivacaine with the status of S6K1 activity and we present evidence that decrease in cell growth and proliferation by bupivacaine is mediated through inactivation of S6 kinase 1 in a concentration and time dependent manner. We also show that ectopic expression of constitutively active S6 kinase 1 imparts substantial protection from bupivacaine induced cytotoxicity. Inactivation of S6K1 though associated with loss of putative mTOR mediated phosphorylation did not correspond with loss of similar phosphorylations in 4EBP1 indicating that S6K1 inhibition was not mediated through inactivation of mTORC1 signaling pathway or its down regulation.

The Mechanisms Underlying Lipid Resuscitation Therapy

“…26 Whereas acute toxicity drives loss of insulinergic signaling, bathing cells overnight in bupivacaine induces cell death through apoptotic signaling at translational and mitochondrial targets downstream of Akt and mTOR. [27][28][29] In addition to loss of growth-related signaling, local anesthetics exert direct independent actions, which appreciably perturb the myocardial contractility apparatus. 30 It is unclear if these effects are the result of altered signaling at the membrane or an independent action.…”

“…25 At high concentrations, local anesthetics drive proapoptotic signaling by blocking ERK along with Akt, resulting in cytotoxicity in mice myoblasts. 28 Local anesthetic challenge also diminishes signaling downstream of mTORC1 with resulting dephosphorylation of ribosomal protein s6 27 and interference with autophagosome clearance. 114 At sufficiently high concentrations, bupivacaine drives opening of the mitochondrial permeability transition pore (mPTP), which leads to calcium leak, release of cytochrome C, activation of apoptosis, and death of myocytes.…”

High-Content Screening: Understanding and Managing Mechanistic Data to Better Predict Toxicity

“…HepG2 are cycling cells and primary hepatocytes are not, therefore, the potential differences observed may not be due to cytotoxicity, but reduced cell number as several of these compounds are known cell cycle inhibitors. For example, amitriptyline was reported to inhibit D -cyclin transactivation and arrest cells at the G 0 /G 1 phase of the cell cycle [ 42 ], bupivacaine was found to arrest cell growth by inactivating ribosomal protein S6 kinase 1 [ 43 ], nocodazole is an antimicrotubule agent that was shown to arrest cells in the G2/M phase of the cell cycle [ 44 ] and etoposide is a topoisomerase II (topo II) inhibitor [ 45 ].…”

Insulin Signaling in Bupivacaine-induced Cardiac Toxicity

“…However the cellular signaling underlying this effect is unknown. Recent reports demonstrate that bupivacaine disrupts targets of classical insulin signaling 6 including protein kinase B (Akt) and ribosomal protein s6 kinase 1, in cellular models 7,8 . Further, the amide-linked local anesthetics, ropivacaine and lidocaine, disrupt assembly of phosphoinositide-3-kinase (Pi3k) thereby blocking phosphorylation of Akt 9 , an effect that is independent of classical sodium-channel blockade 10 .…”