Abstract 538: Inhibition of progression of malignant melanomas in B16F10 murine model by mecombinant N-acetylgalactosamine-4-Sulfatase (arylsulfatase B)
Authors: Tobacman Joanne Kramer , O-Sullivan Insug , Bhattacharyya Sumit 
Published: June 2023

Abstract
Introduction: Lower expression and activity of N-acetylgalactosamine-4-sulfatase (Arylsulfatase B; ARSB) were inversely associated with increased invasiveness in seven human melanoma cell lines (Oncotarget 2017, 8(3):4169-4180). The decline in ARSB occurred as chondroitin 4-sulfate, a substrate of ARSB, increased. Also, expression of CSPG4 (chondroitin sulfate proteoglycan 4), pro-MMP (matrix metalloproteinase)-2, and PD-L1 (programmed death-ligand 1) increased, as ARSB declined. In vitro exposure of malignant melanoma cells to exogenous recombinant human (rh)ARSB (R&D Systems, Bio-Techne), reduced invasiveness and reduced BrdU incorporation of the malignant melanoma cells.
Experiment: To further assess the impact of exogenous ARSB on progression of melanoma, the progression of subcutaneous B16F10 murine melanomas was tested with rhARSB. Following subcutaneous (SC) injection of 250,000 B16F10 cells (ATCC) in the right flank of 9-10-week-old female mice, control (n=12) and treated mice (n=28) were observed for up to 30 days. Doses of ARSB ranged from 0.1-0.4 mg/kg administered SC at the tumor site on days 2,7,14, and 21 or, alternatively in one group, administered on days 2,7,11,15, and 19, following tumor cell injection.
Summary of Data: Survival was significantly increased, and tumor growth rate and tumor volume were significantly reduced in the treated mice (p&lt;0.001). The dose of 0.2 mg/kg was superior to 0.1 mg/kg, but the effect of further dose increase or of increase in treatment frequency was marginal. Mean tumor volume in control mice was 1.41 ± 0.78 cm3 on day 14 post tumor injection and 3.06 ± 1.09 cm3 on day 17, compared to 0.27 ± 0.18 cm3 on day 14 and 0.37 ± 0.09 cm3 on day 17 in mice treated by 0.2 mg/kg ARSB on days 2,7, and 14. Six control mice died by day 18 post-tumor injection, in contrast to no deaths in treated mice by day 18. Three mice treated with ARSB had no palpable tumor when euthanized. In the untreated mice with tumors, chondroitin sulfate tumor content was 12.02 ± 0.84 µg/mg protein, compared to 8.10 ± 0.61 µg/mg protein in the treated mice. Expression of PD-L1 declined to &lt;35% of the untreated tumor level in the treated mice, and tumor PD-L1 declined to 575 ± 182 pg/mg protein, compared to untreated tumor value of 1225 ± 273 pg/mg protein. Expression of CHST (carbohydrate sulfotransferase) 15, pro-MMP2, and CSPG4 all declined following exogenous ARSB. In contrast, CHST11 expression increased to 1.85 times the control level. No metastases were evident in either untreated or treated mice.
Conclusion: Treatment with exogenous recombinant ARSB reduced tumor progression and improved survival in the subcutaneous murine B16F10 malignant melanoma model. ARSB acts as a tumor suppressor gene and impacts on expression of critical genes associated with melanoma, including PD-L1, CSPG4, and pro-MMP2.
Citation Format: Joanne Kramer Tobacman, Insug O-Sullivan, Sumit Bhattacharyya. Inhibition of progression of malignant melanomas in B16F10 murine model by mecombinant N-acetylgalactosamine-4-Sulfatase (arylsulfatase B) [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 538.