Abstract 2655: HYAL4: A molecular driver and potential marker of invasive bladder cancer
Authors: Lahorewala Sarrah S. , Morera Daley S. , Jordan Andre R. , Lokeshwar Vinata B. 
Published: August 2018

INTRODUCTION AND OBJECTIVES: Muscle invasive bladder cancer (MIBCa) causes the majority of morbidity and mortality in BCa patients. Prognosis of MIBCa patients may be improved by ide ntification of novel prognostic biomarkers and therapeutic targets. Chondroitin sulfate proteoglycans are known to promote tumor growth and metastasis. However, a Chondroitinase (Chase) that degrades chondroitin sulfate has not been identified. HYAL4, a member of the glycosaminoglycan (GAG) degrading enzyme-family, potentially has Chase activity; however, HYAL4 (HY4) has not be studied in any biological system, normal or disease. The objective of this study was to evaluate the expression of all six members of the GAG-degrading enzyme family in bladder cancer (BCa) specimens and to investigate HY4 functions in preclinical models of BCa.

METHODS: Q-PCR was performed to measure mRNA levels of GAG-degrading enzyme family genes in 59 bladder tissues (normal (NBL) = 25; tumor (TBL) = 38). HY4 expression was also measured in 40 cystectomy specimens from MIBCa patients who later were treated for metastatic disease with Gemcitabine plus cisplatin (G+C) chemotherapy. HY4 was either stably expressed or knocked-down in immortalized urothelial and BCa cell lines. Transfectants were assayed for Chase activity, anchorage independent growth, motility, invasion, molecular signaling. Tumor growth and metastasis was monitored by bioluminescence imaging.

RESULTS: Among the 6 genes, HYAL1 and HY4 mRNA levels were significantly (6-13-fold) elevated in TBL tissues when compared to NBL tissues (P&lt;0.001). HY4 levels were 7-fold elevated in muscle invasive BCa. In univariate and multivariate analyses, HY4 predicted metastasis and death due to BCa (chi-sq: 6.93; P=0.0089; risk-ratio: 6.9). In metastatic BCa patients, high HY4 levels significantly correlated with G+C treatment failure (χ2 = 7.5; P=0.0062) with &gt; 80% accuracy. HY4-expressing transfectants secreted HY4 and Chase activity in their conditioned media. Overexpression of HYAL-4 in normal urothelial and BCa cells significantly increased, while its knockdown abrogated, anchorage-independent growth, invasion, and chemotactic motility (&gt; 3-fold). HY4 expression induced Gemcitabine resistance (IC50: vector: 3.1 nM; HY4: 126 nM). HY4 expression upregulated a stem cell signature. Urothelial cells expressing HY4 formed tumors in NOD/SCID mice. HY4-expressing BCa cells metastasized to lung and spleen in an orthotopic BCa model.

CONCLUSION: This first study on HY4 shows that it is a novel molecular determinant of MIBCa and Gemcitabine resistance and a potential marker for clinical outcome.

Citation Format: Sarrah S. Lahorewala, Daley S. Morera, Andre R. Jordan, Vinata B. Lokeshwar. HYAL4: A molecular driver and potential marker of invasive bladder cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 2655.