CPI-613 rewires lipid metabolism to enhance pancreatic cancer apoptosis via the AMPK-ACC signaling

Abstract

Background Pancreatic cancer remains one of the most rapidly progressive and deadly malignancies worldwide. Current treatment regimens only result in small improvements in overall survival for patients with this cancer type. CPI-613 (Devimistat), a novel lipoate analog inhibiting mitochondrial metabolism, shows the new hope for pancreatic cancer treatment as an efficient and well-tolerated therapeutic option treated alone or in combination with chemotherapy. Methods Pancreatic cancer cells growing in planar 2D cultures and 3D scaffold were used as research platforms. Cell viability was measured by MTT and alamarBlue, and apoptosis was assessed by JC-1 staining and flow cytometry with Annexin V-FITC/PI staining. The mechanism behind CPI-613 action was analyzed by western blot, transmission electron microscopy, and lipolysis assay kits, in the presence or absence of additional signaling pathway inhibitors or gene modifications. Results CPI-613 exhibits anticancer activity in pancreatic cancer cells by triggering ROS-associated apoptosis, which is accompanied by increased autophagy and repressed lipid metabolism through activating the AMPK signaling. Intriguingly, ACC, the key enzyme modulating lipid metabolism, is identified as a vital target of CPI-613, which is inactivated in an AMPK-dependent manner and influences apoptotic process upon CPI-613. Blockade or enhancement of autophagic process does not increase or blunt apoptosis to CPI-613, but inhibition of the AMPK-ACC signaling significantly attenuates apoptosis induced by CPI-613, suggesting CPI-613-mediated lipid metabolism reduction contributes to its cytotoxicity in pancreatic cancer cells. Conclusions These findings explore the critical role of lipid metabolism in apoptosis, providing new insights into the AMPK-ACC signaling axis in crosstalk between lipid metabolism and apoptosis in CPI-613 treatment.

Targeting Altered Energy Metabolism in Colorectal Cancer: Oncogenic Reprogramming, the Central Role of the TCA Cycle and Therapeutic Opportunities

“…Furthermore, carnosine, an inhibitor of glycolytic ATP production, and CPI-613 act synergistically by depriving all energy sources originating from glucose [ 203 ]. Primarily targeting the TCA cycle, CPI-613 has marginal effects on proteins of the glycolytic pathway, such as HK I and II, lactate dehydrogenase A (LDHA) and pyruvate kinase M2 (PKM2) in vitro [ 211 ]. Furthermore, CPI-613 was also shown to impact lipid metabolism mediated by the 5′ AMP-activated protein kinase (AMPK)–Acetyl-coenzyme A carboxylase (ACC) axis, as shown in CPI-613-treated pancreatic cancer cell lines with decreased lipid accumulation [ 211 ].…”

“…Primarily targeting the TCA cycle, CPI-613 has marginal effects on proteins of the glycolytic pathway, such as HK I and II, lactate dehydrogenase A (LDHA) and pyruvate kinase M2 (PKM2) in vitro [ 211 ]. Furthermore, CPI-613 was also shown to impact lipid metabolism mediated by the 5′ AMP-activated protein kinase (AMPK)–Acetyl-coenzyme A carboxylase (ACC) axis, as shown in CPI-613-treated pancreatic cancer cell lines with decreased lipid accumulation [ 211 ]. The disruption of carbon and energy flux as well as the perpetuation with biosynthetic intermediate supply by CPI-613 leads to selective cancer cell death in a variety of in vitro and in vivo models (see below).…”

“…Microarray data showed the reduced expression levels of cyclins as well as CDK2 , p27 and p19 , which point to a preceding cell cycle arrest [ 217 , 218 ]. Upon treatment with CPI-613, apoptosis characterized by Caspase-3 and PARP1-cleavage, an increase in pro-apoptotic Bax or NOXA and a decrease in anti-apoptotic Bcl-2 as well as membrane blebbing were found in H460, LNCaP, AsPC-1 and PANC-1 cells [ 211 ]. However, the pan-caspase inhibitor zVAD was not able to reverse this effect [ 194 ].…”

“…Thus, multiple redundant pathways (e.g., necrosis) are triggered by CPI-613 [ 194 ]. Apoptosis was elicited in a ROS-dependent manner as shown using N -acetyl cysteine as an antioxidant in the pancreatic cancer cell lines AsPC-1 and PANC-1 [ 211 ]. Partially contradicting, Egawa et al failed to detect apoptotic features, such as DNA fragmentation, in fibroblasts, which suggests a cell type-dependent mode of action [ 219 ].…”

“…As visualized using transmission electron microscopy, mitochondrial morphology was altered by CPI-613, showing reduced mitochondrial cristae junctions and overall disrupted cristae morphology in pancreatic cancer cell lines. These morphological changes occurred concomitantly to mitochondrial membrane dissipation [ 211 ]. Surprisingly, chronic treatment with CPI-613 does not reduce mitochondrial number and size, but only impairs mitochondrial membrane potential in cell culture models [ 194 , 220 ], which is also observed in an irreversible manner upon short-term treatment.…”