Prognostic potential of DNA methylation and transcript levels of HIF1A and EPAS1 in colorectal cancer.
Hypoxic conditions during the formation of colorectal cancer may support the development of more aggressive tumors. Hypoxia-inducible factor (HIF) is a heterodimeric complex, composed of oxygen-induced HIFα and constitutively expressed HIFβ subunits, which mediates the primary transcriptional response to hypoxic stress. Among HIFα isoforms, HIF1α (HIF1A) and endothelial PAS domain-containing protein 1 (EPAS1) are able to robustly activate hypoxia-responsive gene signatures. Although posttranslational regulation of HIFα subunits is well described, less is known about their transcriptional regulation. Here, molecular analysis determined that EPAS1 mRNA was significantly reduced in primary colonic adenocarcinoma specimens compared with histopathologically nonneoplastic tissue from 120 patients. In contrast, no difference in HIF1A mRNA levels was observed between cancerous and noncancerous tissue. Bisulfite DNA sequencing and high-resolution melting analysis identified significant DNA hypermethylation in the EPAS1 regulatory region from cancerous tissue compared with nonneoplastic tissue. Importantly, multivariate Cox regression analysis revealed a high HR for patients with cancer with low EPAS1 transcript levels (HR, 4.91; 95% confidence interval, CI, 0.42-56.15; P = 0.047) and hypermethylated EPAS1 DNA (HR, 33.94; 95% CI, 2.84-405.95; P = 0.0054). Treatment with a DNA methyltransferase inhibitor, 5-Aza-2'-deoxycytidine (5-aza-dC/Decitabine), upregulated EPAS1 expression in hypoxic colorectal cancer cells that were associated with DNA demethylation of the EPAS1 regulatory region. In summary, EPAS1 is transcriptionally regulated by DNA methylation in colorectal cancer.


CONCLUSIONS
DNA methylation and mRNA status of EPAS1 have novel prognostic potential for colorectal cancer.
Departments of Biochemistry and Molecular Biology and arawluszko@ump.edu.pl.
Agnieszka Anna
AA
Rawłuszko-Wieczorek
General and Colorectal Surgery, Poznań University of Medical Sciences, Poland.
Karolina
K
Horbacka
General and Colorectal Surgery, Poznań University of Medical Sciences, Poland.
Piotr
P
Krokowicz
Departments of Biochemistry and Molecular Biology and.
Matthew
M
Misztal
Departments of Biochemistry and Molecular Biology and.
Paweł Piotr
PP
Jagodziński
D000230:Adenocarcinoma / Q000235:genetics / Q000473:pathology; D000368:Aged; D051792:Basic Helix-Loop-Helix Proteins / Q000235:genetics*; D015179:Colorectal Neoplasms / Q000235:genetics* / Q000473:pathology; D019175:DNA Methylation / Q000235:genetics*; D005260:Female; D006801:Humans; D000860:Hypoxia / Q000235:genetics / Q000473:pathology; D051795:Hypoxia-Inducible Factor 1, alpha Subunit / Q000235:genetics*; D008297:Male; D011379:Prognosis; D012333:RNA, Messenger / Q000235:genetics; D000099162:Endothelial PAS Domain-Containing Protein 1
D051792:Basic Helix-Loop-Helix Proteins; D051795:Hypoxia-Inducible Factor 1, alpha Subunit; D012333:RNA, Messenger; D000099162:Endothelial PAS Domain-Containing Protein 1; C497442:HIF1A protein, human