K. Rouse1, G. Toro2, P. Szaniszlo2, B. Servantes2, M. Hellmich2, K. Modis2 1University Of Texas Medical Branch, School Of Medicine, Galveston, TX, USA 2University Of Texas Medical Branch, Department Of Surgery, Galveston, TX, USA
Introduction: In the United States, colorectal cancer (CRC) is the third most diagnosed cancer and the second leading cause of cancer-related deaths after excluding skin cancer. Almost 50% of patients with CRC will develop metastases, in which prognosis is poor. A critical process in tumor development and metastases is cancer-induced angiogenesis. Anti-angiogenic therapeutics have been developed to treat patients with CRC; however, current therapies have shown varying levels of efficacy due to therapeutic resistance. For this reason, there is an urgent need for novel anti-angiogenic therapies that target different molecules and pathways involved in tumor growth and metastasis. 3-mercaptopyruvate sulfurtransferase (3-MST) is a hydrogen sulfide (H2S)-producing enzyme, that is abundantly expressed in endothelial cells (ECs). Significantly elevated levels of H2S have been demonstrated in CRC, however, the role of the 3-MST/H2S axis in tumor angiogenesis remains unknown. This study aims to characterize the regulatory role of EC 3-MST in promoting CRC-associated angiogenesis, as a potential novel anti-angiogenic therapeutic target.
Methods: To assess in vitro angiogenic responses, EA.hy926 human vascular ECs subjected to shRNA-mediated 3-MST were used. Proliferation, migration, and tube-like network formation abilities of sh3-MST ECs were tested by subjecting ECs to complete HCT116 growth media and HCT116 cell-conditioned media (1.7 million cells cultured in 30 mL for 120 hrs). Quantification was performed by measuring the number of tubes, tube length, and determining the tube area (ImageJ 1.45s software, National Institutes of Health). The functional role of EC 3-MST in colon tumor growth, angiogenesis, and metastasis was defined in vivo by 3-MST knockout (KO) mice injected with MC38 murine colon adenocarcinoma cells that were assessed at 6-, 9-, and 12-days post-injection versus wild-type mice.
Results: 3-MST attenuation in ECs significantly reduced EC proliferation, migration, and tube-like network formation in vitro. In addition, sh3-MST ECs developed significantly fewer tubes in HCT116 cell-derived conditioned media. Immunocompetent mice subcutaneously injected with MC38 murine colon adenocarcinoma cells showed increased tumor take in wild-type mice at earlier time points post-injection than 3-MST KO mice.
Conclusion: Reduced 3-MST activity in ECs alters angiogenic mechanisms. The data presented in this study supports the view that the 3-MST/H2S signaling pathway could serve as a potential candidate for future cancer therapies.