Molecular oxygen sensing and PHD-inhibition: implications for colorectal cancer growth

• Applicant: Professor Dr. Martin A. Schneider
• Subject Area: General and Visceral Surgery
• Term: from 2009 to 2015
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 101804013

• Final Report Year: 2019

Final Report Abstract

Oxygen deprivation (hypoxia) is common in solid tumors, and represents a crucial trigger of metastatic growth. On the molecular level, the effects of hypoxia are mediated by hypoxia inducible transcription factors (HIFs). HIF prolyl hydroxylase enzymes (PHD1, PHD2 and PHD3) serve as key molecular oxygen sensors, which regulate the activity of HIFs, as well as other downstream targets. Data obtained during the first funding period had substantiated the hypothesis that the PHD-HIF axis modulates the metastatic expansion of colorectal cancer (CRC). Specifically, expressional analyses in a large collection of human colorectal cancer samples and functionxal genetic studies revealed that underexpression of PHD3 in cancer cells promotes metastatic spread. During the current funding period, we have elucidated the mechanisms underlying anti-metastatic effects of PHD3-expression in colorectal cancer. Migratory potential and colony formation were enhanced in PHD3-deficient cancer cells, and this phenotype was associated with enhanced mitochondrial ATP-production. These effects were accompanied by increased mitochondrial expression of the BCL-2 family member, myeloid leukemia sequence 1 (MCL-1), and could be reversed by simultaneous inhibition of MCL-1. MCL-1 protein expression was likewise enhanced in human colorectal tumors expressing low levels of PHD3. Collectively, these findings demonstrate that down-regulation of PHD3 augments metastatic spread in human colorectal cancer, and identify MCL-1 as a novel downstream-effector of oxygen sensing in colorectal cancer cells. Further studies in gene-deficient mice revealed that specific loss of PHD3 in tumor-associated macrophages did not affect the expansion of colorectal tumors in vivo. On the other hand, we could previously show that inhibition of PHD enzymes stimulates the recovery of liver function following major hepatectomy, which is a common surgical approach to treat colorectal liver metastases (CRLM). In order to assess how these insights could translate into therapeutic applications for patients suffering CRLM, we have assessed the effects of pharmacologic PHD-inhibition on the expansion of colorectal liver metastases in the setting of surgical liver resection. Applying various preclinical mouse models, we could demonstrate that treatment with the pharmacologic PHD enzyme inhibitor 3,4- dihydroxybenzoate (EDHB) selectively augmented liver regeneration after partial hepatectomy and portal vein ligation, without enhancing growth of colorectal metastases. Pharmacological biodistribution studies suggested that this effect was due to significant accumulation of EDHB in the liver, but not in tumors. These findings collectively indicate that pharmacologic inhibition of PHDs using EDHB might represent a novel and safe strategy to augment surgical treatment of CRLM. Currently ongoing studies and future research strategies arising from this subproject aim at further promoting these preclinical findings towards potential clinical application.

Publications

• PHD1 regulates p53-mediated colorectal cancer chemoresistance. EMBO Mol Med 7(10), 1350-1365 (2015)
  Deschoemaeker S, Di Conza G, Lilla S, Martin-Perez R, Mennerich D, Boon L, Hendrikx S, Maddocks O, Marx P, Radhakrishnan P, Prenen H, Schneider M, Myllyharju J, Kietzmann T, Vousden K, Zanivan S and Mazzone M
  
• Therapeutic inhibition of prolyl hydroxylase domain-containing enzymes in surgery: putative applications and challenges. Hypoxia, 3:1-14 (2015)
  Harnoss JM, Strowitzki M, Radhakrishnan P, Platzer L, Harnoss JC, Hank T, Cai J, Ulrich A and Schneider M
  
• Prolyl hydroxylase 3 attenuates MCL-1-mediated ATP production to suppress the metastatic potential of colorectal cancer cells. Cancer Res 76, 2219-2230 (2016)
  Radhakrishnan P, Ruh N, Harnoss JM, Kiss J, Mollenhauer M, Scherr AL, Platzer L, Schmidt T, Podar K, Opferman JT, Weitz J, Schulze-Bergkamen H, Koehler B, Ulrich A and Schneider M
  
• EMX2 gene expression predicts liver metastasis and survival in colorectal cancer. BMC Cancer 17(1), 555 (2017)
  Aykut B, Ochs M, Radhakrishnan P, Brill A, Höcker H, Schwarz S, Weissinger D, Kehm R, Kulu Y, Ulrich A and Schneider M
  
• Prolyl hydroxylase inhibition enhances liver regeneration without induction of tumor growth. Ann Surg 265(4), 782-791 (2017)
  Harnoss JM, Platzer L, Burhenne J, Radhakrishnan P, Cai J, Strowitzki MJ, Weiss J, Ritter AS, Mollenhauer M, Schmidt T, Ulrich A, Haefeli WE and Schneider M
  
• Loss of prolyl-hydroxylase 1 protects against biliary fibrosis via attenuated activation of hepatic stellate cells. Am J Pathol 188(12), 2826-2238 (2018)
  Strowitzki MJ, Kirchberg J, Tuffs C, Schiedeck M, Ritter A, Biller M, Harnoss JM, Lasitschka F, Schmidt T, Radhakrishnan P, Ulrich A and Schneider M
  
• Prognostic indicators lose their value with repeated resection of colorectal liver metastases. Eur J Surg Oncol (2018) 44(10), 1610-1618 (2018)
  Schmidt T, Nienhüser H, Kuna C, Klose J, Strowitzki MJ, Büchler MW, Ulrich A and Schneider M
  
• The PHD1 oxygen sensor in health and disease. J Physiol 2018 Feb 13
  Kennel K, Burmeister J, Schneider M and Taylor C