The mammalian target of rapamycin (mTOR) pathway, which is essential for cell proliferation, is repressed in certain cell types in hypoxia. However, hypoxia-inducible factor 2α (HIF2α) can act as a proliferation-promoting factor in some biological settings. This paradoxical situation led us to study whether HIF2α has a specific effect on mTORC1 regulation. Here we show that activation of the HIF2α pathway increases mTORC1 activity by upregulating expression of the amino acid carrier SLC7A5. At the molecular level we also show that HIF2α binds to the Slc7a5 proximal promoter. Our findings identify a link between the oxygen-sensing HIF2α pathway and mTORC1 regulation, revealing the molecular basis of the tumor-promoting properties of HIF2α in von Hippel-Lindau-deficient cells. We also describe relevant physiological scenarios, including those that occur in liver and lung tissue, wherein HIF2α or low-oxygen tension drive mTORC1 activity and SLC7A5 expression.

Graphical Abstract Highlights d HIF1a reduces intracellular aspartate levels d HIF1a impairs oxidative and reductive aspartate biosynthesis d The aspartate-generating GOT1 and GOT2 enzymes are repressed by HIF1a d Aspartate supplementation counteracts the antiproliferative influence of HIF1a In Brief Melé ndez-Rodríguez et al. show that HIF1a impairs oxidative and reductive aspartate biogenesis, which consequently drives HIF1a-dependent suppression of tumor cell proliferation. Mechanistically, HIF1a represses the aspartate-producing enzymes GOT1 and GOT2 in several biological settings, including human VHL-deficient renal cell carcinoma, in which HIF1a can act as a tumor suppressor.

Paragangliomas or extra-adrenal pheochromocytomas account for approximately 15% of all pheochromocytomas. They are usually found in an intradiaphragmatic location. Paragangliomas of the urinary bladder are infrequent and represent 6% of the paragangliomas and 0.06% of all bladder tumors. We describe 2 cases of urinary bladder paragangliomas attended to our center and review the literature with special attention to treatment, since there is some controversy around the management of these tumors. Surgical options include partial or total cystectomy and transurethral resection, but there is no consensus regarding these treatment modalities. The 2 patients presented underwent transurethral resection with a good outcome and no recurrence or residual disease.

Extracellular signal-regulated kinase 5 (ERK5), also known as big mitogen-activated protein kinase (MAPK) 1, is implicated in a wide range of biologic processes, which include proliferation or vascularization. Here, we show that ERK5 is degraded through the ubiquitin-proteasome system, in a process mediated by the tumor suppressor von Hippel-Lindau (VHL) gene, through a prolyl hydroxylation-dependent mechanism. Our conclusions derive from transient transfection assays in Cos7 cells, as well as the study of endogenous ERK5 in different experimental systems such as MCF7, HMEC, or Caki-2 cell lines. In fact, the specific knockdown of ERK5 in pVHL-negative cell lines promotes a decrease in proliferation and migration, supporting the role of this MAPK in cellular transformation. Furthermore, in a short series of fresh samples from human clear cell renal cell carcinoma, high levels of ERK5 correlate with more aggressive and metastatic stages of the disease. Therefore, our results provide new biochemical data suggesting that ERK5 is a novel target of the tumor suppressor VHL, opening a new field of research on the role of ERK5 in renal carcinomas.

Bladder endometriosis is rare, although the bladder is the urinary tract structure most often affected by this condition. The common clinical manifestations of bladder endometriosis include menouria and urethral and pelvic pain syndrome occurring cyclically. Imaging methods are not conclusive for the definitive diagnosis. Cystoscopy is the most useful diagnostic test with confirmation by histologic study. Treatment must be individualized according to the patient's age, desire for future pregnancies, the severity of the symptoms, the site affected, and whether other organs are involved. Two types of treatment are currently used as follows: medical-hormonal and surgical.