Hypoxia and HIF-1α Regulate Collagen Production in Keloids

Keloids are reactive or spontaneous fibroproliferative dermal tumors characterized by the exaggerated and uncontrolled accumulation of extracellular collagen. Current approaches to mitigate keloidogenesis are largely procedural in nature. However, a better understanding of its biological drivers may lead to novel targeted treatments for keloids. Through whole-genome expression analysis, we found that a HIF-1α transcriptional footprint is preferentially upregulated (activation score=2.024; p=1.05E-19) in keloid fibroblasts (KFs) compared to normal dermal fibroblasts (NFs). We verified that HIF-1α protein is more strongly expressed in keloid specimens compared to normal skin (p=0.035) and that hypoxia (1% O2) leads to increased collagen, especially in the extracellular compartment. Collagen levels were uniformly reduced by selective HIF-1α inhibitor CAY10585. Our results indicate that collagen secretion may be intimately linked to a hypoxic microenvironment within keloid tumors and that HIF-1α blockade could be a novel avenue of treatment for these tumors. Briefly, 10 cell lines (5 NFs and 5 KFs) were grown in replicate cultures and subjected to RNA extraction using the Qiagen RNeasy Mini Kit (Qiagen). 100 ng of total mRNA from 20 samples (10 cell lines in duplicate) were then sent to the Whitehead Institute Genome Technology (WIGT) Core for expression profiling. Standard operating procedures at the WIGT Core are summarized. RNA quality was analyzed using an Agilent 2100 Bioanalyzer. After QC, one of the keloid samples was removed leaving a total of 19 samples (10 NFs and 9 KFs). Briefly, RNA samples with RNA integrity number (RIN) above 9.8 were hybridized to GeneChip PrimeView Human Gene Expression Arrays (Affymetrix,) and analyzed using GeneChip Expression Console. A Primeview CDF (provided by Affymetrix) that included probe information for the ERCC controls (GPL16043) was used to generate the CEL files.