High hepatic expression of PDK4 improves survival upon multimodal treatment of colorectal liver metastases

Moritz J Strowitzki,Martin Schneider,Gwendolyn Kimmer,Sandra Pavicevic,Christopher Tuffs,Claudia Volz,Johannes Klose,Florian Vondran,Alina S Ritter,Thomas Schmidt,Jonathan M Harnoss,Praveen Radhakrishnan,Jana Scheer

doi:10.1038/s41416-019-0406-9

Abstract

BackgroundPatients with borderline resectable colorectal liver metastases (CRLM) frequently receive neoadjuvant chemotherapy (NC) to reduce tumour burden, thus making surgical resection feasible. Even though NC can induce severe liver injury, most studies investigating tissue-based prognostic markers focus on tumour tissue. Here, we assessed the prognostic significance of pyruvate-dehydrogenase-kinase isoenzyme 4 (PDK4) within liver tissue of patients undergoing surgical resection due to CRLM.MethodsTranscript levels of hypoxia-adaptive genes (such as PDK isoenzymes) were assessed in the tissue of healthy liver, corresponding CRLM, healthy colon mucosa and corresponding tumour. Uni- and multivariate analyses were performed. Responses to chemotherapy upon up- or down-regulation of PDK4 were studied in vitro.ResultsPDK4 expression within healthy liver tissue was associated with increased overall survival and liver function following surgical resection of CRLM. This association was enhanced in patients with NC. PDK4 expression in CRLM tissue did not correlate with overall survival. Up-regulation of PDK4 increased the resistance of hepatocytes and colon cancer cells against chemotherapy-induced toxicity, whereas knockdown of PDK4 enhanced chemotherapy-associated cell damage.ConclusionOur findings suggest that up-regulated PDK4 expression reduces hepatic chemotherapy-induced oxidative stress and is associated with improved postoperative liver function in patients undergoing multimodal treatment and resection of CRLM.

Highlights

Patients with borderline resectable colorectal liver metastases (CRLM) frequently receive neoadjuvant chemotherapy (NC) to reduce tumour burden, making surgical resection feasible
At the time of surgery healthy liver tissue of patients with NC showed no significant increase of histological signs, such as liver fibrosis, steatosis or steatohepatitis which can be associated with chemotherapy-induced liver damage
In the present study, we demonstrate that high transcript levels of pyruvate-dehydrogenase-kinase isoenzyme 4 (PDK4) within healthy liver tissue of patients with CRLM are associated with increased overall survival and postoperative liver function

Summary

BACKGROUND

Many patients with colorectal cancer (CRC) develop distant organ metastases necessitating surgical resection of both the primary tumour and organ metastases.[1]. Primary tumour, number of CRLMs, operations performed, chemotherapy protocols, histological signs of chemotherapy-induced liver damage (hepatic fibrosis, steatosis or steatohepatitis) and postoperative course (patient morbidity and mortality; serum levels indicating liver function and injury) was obtained from patients’ medical charts, pathological reports and surgery protocols. Murine hepatocytes (AML12 cells) were cultured in equal ratio of DMEM/F12 (Sigma-Aldrich, Taufkirchen, Germany) and DMEM high glucose 25 mM (Sigma-Aldrich) medium with insulin, transferrin and selenium (ITS-G, Thermo Fisher Scientific, Waltham, USA), supplemented with 10% FCS and 1% penicillin/streptomycin. Transient PDK4 knock-in was performed using a CRISPR activation plasmids (human: sc-401355-ACT; mouse: sc-424220-ACT; Santa Cruz, Heidelberg, Germany), mixed with UltraCruz® Transfection Reagent (Santa Cruz), according to the manufacturer’s protocol. We performed two-sided testing and considered a P-value of

RESULTS

DISCUSSION