To determine if our cell line data were relevant to human
kidney cancers, we next asked whether HIF1α activity is diminished
in human kidney cancers that have sustained 14q
deletions encompassing the HIF1α locus. Toward this end,
we performed gene expression profiling on the cell lines described
above that either expressed both HIF1α and HIF2α
(either naturally or by virtue of induced expression of HIF1α)
or expressed HIF2α alone (either naturally or by virtue of a
HIF1α shRNA), followed by supervised clustering to arrive at
a “HIF1α transcriptional signature,” which included known
HIF1α-specific targets, such as BNIP3, PGK1, HK1, and TPI1
(Fig. 7A; refs. 10, 34). Gene set enrichment analysis (GSEA)
using this HIF1α signature and gene expression data from
52 VHL–/– clear cell renal carcinomas, including 32 without a
HIF1α deletion and 20 with a HIF1α deletion, confirmed that
HIF1α activity is diminished in tumors that have sustained
a 14q deletion spanning the HIF1α locus (P < 0.01; Fig. 7B).