Loss of Glycogen Debranching Enzyme AGL Drives Bladder Tumor Growth via Induction of Hyaluronic Acid Synthesis.
OBJECTIVE
We demonstrated that amylo-alpha-1-6-glucosidase-4-alpha-glucanotransferase (AGL) is a tumor growth suppressor and prognostic marker in human bladder cancer. Here we determine how AGL loss enhances tumor growth, hoping to find therapeutically tractable targets/pathways that could be used in patients with low AGL-expressing tumors.


METHODS
We transcriptionally profiled bladder cell lines with different AGL expression. By focusing on transcripts overexpressed as a function of low AGL and associated with adverse clinicopathologic variables in human bladder tumors, we sought to increase the chances of discovering novel therapeutic opportunities.


RESULTS
One such transcript was hyaluronic acid synthase 2 (HAS2), an enzyme responsible for hyaluronic acid (HA) synthesis. HAS2 expression was inversely proportional to that of AGL in bladder cancer cells and immortalized and normal urothelium. HAS2-driven HA synthesis was enhanced in bladder cancer cells with low AGL, and this drove anchorage-dependent and independent growth. siRNA-mediated depletion of HAS2 or inhibition of HA synthesis by 4-methylumbelliferone (4MU) abrogated in vitro and xenograft growth of bladder cancer cells with low AGL. AGL and HAS2 mRNA expression in human tumors was inversely correlated in patient datasets. Patients with high HAS2 and low AGL tumor mRNA expression had poor survival, lending clinical support to xenograft findings that HAS2 drives growth of tumors with low AGL.


CONCLUSIONS
Our study establishes HAS2-mediated HA synthesis as a driver of growth of bladder cancer with low AGL and provides preclinical rationale for personalized targeting of HAS2/HA signaling in patients with low AGL-expressing tumors.
Department of Surgery (Urology), University of Colorado, Denver, Colorado. Department of Pharmacology, University of Colorado, Denver, Colorado.
Sunny
S
Guin
Department of Surgery (Urology), University of Colorado, Denver, Colorado. Department of Pharmacology, University of Colorado, Denver, Colorado.
Yuanbin
Y
Ru
Department of Surgery (Urology), University of Colorado, Denver, Colorado. Department of Pharmacology, University of Colorado, Denver, Colorado.
Neeraj
N
Agarwal
Department of Surgery (Urology), University of Colorado, Denver, Colorado. Department of Pharmacology, University of Colorado, Denver, Colorado.
Carolyn R
CR
Lew
Department of Surgery (Urology), University of Colorado, Denver, Colorado. Department of Pharmacology, University of Colorado, Denver, Colorado.
Charles
C
Owens
IRCCS Foundation Ca' Granda Ospedale Maggiore Policlinico, Milan, Italy.
Giacomo P
GP
Comi
Department of Surgery (Urology), University of Colorado, Denver, Colorado. Department of Pharmacology, University of Colorado, Denver, Colorado. University of Colorado Comprehensive Cancer Center, Denver, Colorado. dan.theodorescu@ucdenver.edu.
Dan
D
Theodorescu
D000818:Animals; D014408:Biomarkers, Tumor / Q000096:biosynthesis* / Q000235:genetics; D045744:Cell Line, Tumor; D015972:Gene Expression Regulation, Neoplastic; D014453:Glucuronosyltransferase / Q000096:biosynthesis* / Q000235:genetics; D006004:Glycogen Debranching Enzyme System / Q000235:genetics; D064593:Heterografts; D006801:Humans; D000076002:Hyaluronan Synthases; D006820:Hyaluronic Acid / Q000096:biosynthesis; D006923:Hymecromone / Q000008:administration & dosage; D051379:Mice; D015398:Signal Transduction; D001749:Urinary Bladder Neoplasms / Q000235:genetics* / Q000473:pathology
D014408:Biomarkers, Tumor; D006004:Glycogen Debranching Enzyme System; D006923:Hymecromone; D006820:Hyaluronic Acid; D014453:Glucuronosyltransferase; C101754:HAS2 protein, human; D000076002:Hyaluronan Synthases