Introduction: Precision-based treatment approaches could improve the prognosis of patients with bladder cancer (BC). We recently discovered a first-in-class human Chondroitinase (Chase) that degrades chondroitin sulfate. This Chase is a splice variant of HYAL4 (V1) and promotes a malignant phenotype and chemoresistance in BC cells. We evaluated V1/Chase expression and functions in BC and inhibitors to overcome V1/Chase-mediated Gemcitabine (Gem) resistance.
Methods: Cohort 1: 86 bladder tissues (normal (NBL) = 34; tumor (TBL) = 52); cohort 2: 40 cystectomy specimens from MIBC patients who received adjuvant Gemcitabine plus cisplatin (G+C) treatment. Cohort 3: 144 urine specimens (BCA = 42, non-BCa = 102). Gene expression was measured by q-PCR in all cohorts and urine was assayed for Chase activity. V1/Chase was stably expressed or silenced in normal urothelial and three BC cell lines. Transfectants were analyzed for sensitivity to Gemcitabine and Cisplatin. The mechanism of Gem resistance was evaluated in preclinical in vitro and in vivo models.
Results: In cohort 1, V1 mRNA levels were an independent predictor of metastasis and death due to BC (P=0.0008). In cohort 2, high V1 levels significantly predicted with G+C treatment failure (P <0.0001). In cohort 3, Chase levels were 13 to 75-fold elevated in low and high-grade BC patients’ urine compared to non-BC cases (92.7% sensitivity; 88.2% specificity). V1-expressing urothelial and BC cells were resistant to Gem but not to Cisplatin. V1 expression increased Gem metabolism and subsequent efflux of an inactive metabolite dFdU. V1 increased CD44 shedding the conditioned media. This triggered intracellular activation of the JAK2/STAT3 pathway, resulting in the upregulation of cytidine deaminase (CDA). CDA induces Gem metabolism and dFdU efflux. JAK2, STAT3 and CDA inhibitors, (some FDA-approved), synergistically re- sensitized V1-expressing cells to Gem. V1-induced muscle invasive tumors that were metastatic. While Gem inhibited BC xenograft growth, V1-expressing tumors were resistant. Combination of Gem with a CDA inhibitor (tetrahydrouridine) abrogated V1 tumor growth with minimal toxicity.
Conclusions: V1 is a functional biomarker that drives muscle-invasion, metastasis and Gem resistance in BC. Inhibitors of the JAK2/STAT3/CDA pathway overcome V1- mediated Gem resistance, suggesting a precision-based treatment approach to improve treatment response.
Source of Funding: 1R01CA227277-01A1 (VBL); Department of Defence-PRCRP (W81XWH1810277 (CA170470; PRCRP)
.jpg)
.jpg)
