title: Tuberous sclerosis complex protein 1 expression is affected by VHL Gene alterations and HIF-1α production in sporadic clear-cell renal cell carcinoma.
abstract: Alterations in von Hippel-Lindau gene (VHL) do not determine deregulation of hypoxia-inducible factors (HIFs) in clear-cell renal carcinoma (ccRCC). Their effects on tuberous sclerosis proteins (TSC1/2) and heat shock protein 90 (Hsp90) expressions in sporadic ccRCC are unknown. Therefore, we analyze the impact of VHL alterations and HIF-α production on the expression of TSC proteins and Hsp90 in these tumors. Alterations in VHL gene region exhibited 37/47 (78.7%) tumors. Monoallelic inactivation (intragenic mutation or LOH) was found in 10 (21.3%) and biallelic inactivation (intragenic mutation plus LOH) in 27 (57.4%) ccRCCs. Tumorous expression of HIF-α mRNAs, HIF-α, Hsp90 and TSC2 were VHL independent; TSC2 was underexpressed in all tumors by immunostaining (P<0.001). Immunoblotting revealed that TSC1 production was lower in tumors with monoallelic VHL inactivation than in control (P=0.01) and tissues with biallelic VHL inactivation (P=0.019), while tumors lacking HIF-1α (16/47) concurrently overexpressed HIF-2α and underexpressed TSC1 in comparison to controls (P=0.01 for both) and HIF-1α positive tumors (P=0.015 and P=0.050). Significant portion of variability (56.4%) in tumor diameter was explained by oscillations in nuclear grade, and TSC1 and HIF-2α expression in VHL altered tumors. In conclusion, while TSC2 is broadly downregulated in sporadic ccRCC, TSC1 expression is reduced in two subsets of these tumors, those with monoallelic VHL gene inactivation and those with concurrent low HIF-1α and high HIF-2α expression. Hence, the involvement of nuclear grade, TSC1 and HIF-2α in the progression of VHL altered tumors, implies the interplay between pVHL and TSC1.
authors.affiliation: Clinic for Endocrinology, Diabetes and Metabolic Diseases, Medical School, University of Belgrade, Department for Neuroendocrine Tumors and Hereditary Cancer Syndromes, Dr Subotica 13, Belgrade, Serbia. Electronic address: svetadamjanovic@gmail.com.
authors.forename: Svetozar S
authors.initials: SS
authors.lastname: Damjanovic
authors.affiliation: Clinic for Endocrinology, Diabetes and Metabolic Diseases, Medical School, University of Belgrade, Department for Neuroendocrine Tumors and Hereditary Cancer Syndromes, Dr Subotica 13, Belgrade, Serbia.
authors.forename: Bojana B
authors.initials: BB
authors.lastname: Ilic
authors.affiliation: Clinic for Endocrinology, Diabetes and Metabolic Diseases, Medical School, University of Belgrade, Department for Neuroendocrine Tumors and Hereditary Cancer Syndromes, Dr Subotica 13, Belgrade, Serbia.
authors.forename: Bojana B
authors.initials: BB
authors.lastname: Beleslin Cokic
authors.affiliation: Clinic for Endocrinology, Diabetes and Metabolic Diseases, Medical School, University of Belgrade, Department for Neuroendocrine Tumors and Hereditary Cancer Syndromes, Dr Subotica 13, Belgrade, Serbia.
authors.forename: Jadranka A
authors.initials: JA
authors.lastname: Antic
authors.affiliation: Clinic for Endocrinology, Diabetes and Metabolic Diseases, Medical School, University of Belgrade, Department for Neuroendocrine Tumors and Hereditary Cancer Syndromes, Dr Subotica 13, Belgrade, Serbia.
authors.forename: Jovana Z
authors.initials: JZ
authors.lastname: Bankovic
authors.affiliation: Clinic for Endocrinology, Diabetes and Metabolic Diseases, Medical School, University of Belgrade, Department for Neuroendocrine Tumors and Hereditary Cancer Syndromes, Dr Subotica 13, Belgrade, Serbia.
authors.forename: Ivana T
authors.initials: IT
authors.lastname: Milicevic
authors.affiliation: Clinic for Endocrinology, Diabetes and Metabolic Diseases, Medical School, University of Belgrade, Department for Neuroendocrine Tumors and Hereditary Cancer Syndromes, Dr Subotica 13, Belgrade, Serbia.
authors.forename: Gordana S
authors.initials: GS
authors.lastname: Rodic
authors.affiliation: Clinic for Endocrinology, Diabetes and Metabolic Diseases, Medical School, University of Belgrade, Department for Neuroendocrine Tumors and Hereditary Cancer Syndromes, Dr Subotica 13, Belgrade, Serbia.
authors.forename: Dusan S
authors.initials: DS
authors.lastname: Ilic
authors.affiliation: Institute for Histology and Embryology, School of Medicine of Military Medical Academy, University of Defense, Belgrade, Serbia.
authors.forename: Vera N
authors.initials: VN
authors.lastname: Todorovic
authors.affiliation: Institute of Histology and Embryology, Medical School, University of Belgrade, Belgrade, Serbia.
authors.forename: Nela
authors.initials: N
authors.lastname: Puskas
authors.affiliation: Clinic for Urology, Medical School, University of Belgrade, Belgrade, Serbia.
authors.forename: Cane D
authors.initials: CD
authors.lastname: Tulic
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002292:Carcinoma, Renal Cell / Q000235:genetics* / Q000378:metabolism / Q000473:pathology; D005260:Female; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D051795:Hypoxia-Inducible Factor 1, alpha Subunit / Q000235:genetics* / Q000378:metabolism; D007680:Kidney Neoplasms / Q000235:genetics* / Q000378:metabolism / Q000473:pathology; D008297:Male; D008875:Middle Aged; D009154:Mutation; D000077004:Tuberous Sclerosis Complex 1 Protein; D000077005:Tuberous Sclerosis Complex 2 Protein; D025521:Tumor Suppressor Proteins / Q000235:genetics* / Q000378:metabolism; D051794:Von Hippel-Lindau Tumor Suppressor Protein / Q000235:genetics* / Q000378:metabolism
chemical_list: C497442:HIF1A protein, human; D051795:Hypoxia-Inducible Factor 1, alpha Subunit; C000624650:TSC1 protein, human; C000624653:TSC2 protein, human; D000077004:Tuberous Sclerosis Complex 1 Protein; D000077005:Tuberous Sclerosis Complex 2 Protein; D025521:Tumor Suppressor Proteins; D051794:Von Hippel-Lindau Tumor Suppressor Protein; C497446:VHL protein, human
keywords: Clear-cell renal cell carcinoma; Heat shock protein 90; Hypoxia-inducible factors; Tuberous sclerosis complex protein 1 and 2; VHL gene