In a search for potential synthetic-lethal targets for FLCN using a phosphatase siRNA library screening approach, we found that knockdown of SSH2 serine phosphatase (one of the three members of Slingshot family and previously implicated in actin reorganization) specifically induced Caspase3/7 activity in a dose-dependent manner (up to six-fold increase, 10 nM, 72 h) in two human FLCN-deficient cell lines (BHD-origin renal cell carcinoma UOK257 and thyroid carcinoma FTC133) but not in their folliculin expressing isogenic cell lines.
Although CA XII expression levels tended to be lower in RCC cell lines without the VHL mutation and in transformants of the wild-type VHL gene, the results were not conclusive.
Although histologically distinct RCC subtypes exist, emerging themes shared between hereditary and sporadic RCC include dysregulation of the von Hippel-Lindau tumor suppressor protein/hypoxia inducible factor axis, defective ciliogenesis, and aberrant tumor metabolism.
As the identification of novel pVHL targets might provide insights into pVHL tumour suppressor activity, we performed gene expression microarray analysis in VHL-wild-type and VHL-null renal cell carcinoma (RCC) cell lines.
The availability of a RCC cell line from a VHL patient would be useful in studies comparing sporadic RCC with RCC resulting from VHL syndrome; and for determining the relationship or interaction of the RCC gene with the VHL gene to produce a common tumor type.
The von Hippel-Lindau (VHL) gene is often inactivated (by mutation or promoter hypermethylation) in renal cell carcinoma but the relation to therapeutic outcome is unclear.
For an early diagnosis of VHL, before the occurrence of cancers (especially renal cell carcinoma), it is of huge importance to initiate VHL genetic testing in at-risk patients.
Herein, we provide mechanistic evidence that HIF-2α can be degraded in cytoplasm under hypoxic conditions via the 26S proteasome and that MDM2 is the E3 ligase which induces the hypoxic degradation of HIF-2α in PI-3K-dependent manner in VHL-deficient RCC cells.
Our data provide insight into the link between HIF2α, the ITPR1-related pathway, and natural immunity and strongly suggest a role for the HIF2α/ITPR1 axis in regulating RCC cell survival.
Two correlated variants (r² = 0.99 in controls), rs11894252 (P = 1.8 × 10⁻⁸) and rs7579899 (P = 2.3 × 10⁻⁹), map to EPAS1 on 2p21, which encodes hypoxia-inducible-factor-2 alpha, a transcription factor previously implicated in RCC.
These data support the notion of a putative genotoxic effect of TCE leading to VHL gene damage and subsequent occurrence of RCC in highly exposed subjects.