title: mTORC2 activation is regulated by the urokinase receptor (uPAR) in bladder cancer.
abstract: Mammalian target of rapamycin complex 2 (mTORC2) has been identified as a major regulator of bladder cancer cell migration and invasion. Upstream pathways that mediate mTORC2 activation remain poorly defined. Urokinase-type plasminogen activator receptor (uPAR) is a GPI-anchored membrane protein and known activator of cell-signaling. We identified increased uPAR expression in 94% of invasive human bladder cancers and in 54-71% of non-invasive bladder cancers, depending on grade. Normal urothelium was uPAR-immunonegative. Analysis of publicly available datasets identified uPAR gene amplification or mRNA upregulation in a subset of bladder cancer patients with reduced overall survival. Using biochemical approaches, we showed that uPAR activates mTORC2 in bladder cancer cells. Highly invasive bladder cancer cell lines, including T24, J82 and UM-UC-3 cells, showed increased uPAR mRNA expression and protein levels compared with the less aggressive cell lines, UROtsa and RT4. uPAR gene-silencing significantly reduced phosphorylation of Serine-473 in Akt, an mTORC2 target. uPAR gene-silencing also reduced bladder cancer cell migration and Matrigel invasion. S473 phosphorylation was observed by immunohistochemistry in human bladder cancers only when the tumors expressed high levels of uPAR. S473 phosphorylation was not controlled by uPAR in bladder cancer cell lines that are PTEN-negative; however, this result probably did not reflect altered mTORC2 regulation. Instead, PTEN deficiency de-repressed alternative kinases that phosphorylate S473. Our results suggest that uPAR and mTORC2 are components of a single cell-signaling pathway. Targeting uPAR or mTORC2 may be beneficial in patients with bladder cancer.
authors: Departments of Pathology, University of California, San Diego, 9500 Gilman Drive, La Jolla, CA 92093, United States.
authors: Andrew M
authors: AM
authors: Hau
authors: Departments of Pathology, University of California, San Diego, 9500 Gilman Drive, La Jolla, CA 92093, United States.
authors: Mariah Z
authors: MZ
authors: Leivo
authors: Departments of Pathology, University of California, San Diego, 9500 Gilman Drive, La Jolla, CA 92093, United States.
authors: Andrew S
authors: AS
authors: Gilder
authors: Departments of Pathology, University of California, San Diego, 9500 Gilman Drive, La Jolla, CA 92093, United States.
authors: Jing-Jing
authors: JJ
authors: Hu
authors: Departments of Pathology, University of California, San Diego, 9500 Gilman Drive, La Jolla, CA 92093, United States.
authors: Steven L
authors: SL
authors: Gonias
authors: Departments of Pathology, University of California, San Diego, 9500 Gilman Drive, La Jolla, CA 92093, United States; Departments of Urology, University of California, San Diego, 9500 Gilman Drive, La Jolla, CA 92093, United States. Electronic address: dhansel@ucsd.edu.
authors: Donna E
authors: DE
authors: Hansel
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D045744:Cell Line, Tumor; D002465:Cell Movement; D005260:Female; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D008297:Male; D000076225:Mechanistic Target of Rapamycin Complex 2 / Q000378:metabolism*; D008875:Middle Aged; D060787:Neoplasm Grading; D009361:Neoplasm Invasiveness; D010766:Phosphorylation; D010768:Phosphoserine / Q000378:metabolism; D011379:Prognosis; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism; D055293:Receptors, Urokinase Plasminogen Activator / Q000378:metabolism*; D015854:Up-Regulation; D001749:Urinary Bladder Neoplasms / Q000235:genetics / Q000378:metabolism* / Q000473:pathology*
chemical_list: D055293:Receptors, Urokinase Plasminogen Activator; D010768:Phosphoserine; D000076225:Mechanistic Target of Rapamycin Complex 2; D051057:Proto-Oncogene Proteins c-akt
keywords: Akt; Cell migration; Urokinase-type plasminogen activator; mTORC2; uPAR