Prostate cancer is one of the most common causes of cancer death in men worldwide, and the treatment options are limited for patients with advanced stages of prostate cancer. Upon oncogenic or inflammatory stimulation, tumor cells or immune cells express cell surface enolase-1 (ENO1) as plasminogen receptor to facilitate their migration via plasmin activation. Little is known about the roles of ENO1 in prostate cancer, especially in the tumor microenvironment (TME). We hypothesized that targeting surface ENO1 with specific mAbs would exert multifactorial therapeutic potentials against prostate cancer. In vivo, we showed ENO1 mAb (HuL227) reduced the growth of subcutaneous PC-3 xenograft, monocytes recruitment, and intratumoral angiogenesis. In a PC-3 intratibial implantation model, HuL227 reduced tumor growth and osteoclast activation in the bone. To investigate the antitumor mechanism of ENO1 mAb, we found that blocking surface ENO1 significantly reduced VEGF-A–induced tube formation of endothelial cells in vitro. Furthermore, HuL227 inhibited inflammation-enhanced osteoclasts activity and the secretion of invasion-related cytokines CCL2 and TGFβ from osteoclasts. In addition, inflammation-induced migration and chemotaxis of androgen-independent prostate cancer cells were dose-dependently inhibited by HuL227. In summary, we showed that, ENO1 mAb targets multiple TME niches involved in prostate cancer progression and bone metastasis via a plasmin-related mechanism, which may provide a novel immunotherapy approach for men with advanced prostate cancer.

Background: Stromal remodeling in the tumor microenvironment contributes to multiple myeloma (MM) progression and drug resistance, but the extracellular mediators that drive these changes remain incompletely defined. Extracellular enolase-1 (ENO1), including membrane-associated and secreted forms, has been implicated in tumor progression; however, its role in cancer-associated fibroblast (CAF)-associated stromal reprogramming in MM is unclear. Methods: The effects of extracellular ENO1 on stromal activation and tumor-supportive functions were examined in MM using MM–bone marrow stromal cell (BMSC) co-cultures, lactate production and viability assays, immunoblotting, cytokine analyses, and a subcutaneous xenograft model of bortezomib (BTZ)-resistant MM in male 6–7-week-old NOD.Cg-Prkdc^scid Il2rg^tm1Vst/Vst (NPG) mice. HuL001, an anti-ENO1 monoclonal antibody, was used to evaluate the therapeutic relevance of extracellular ENO1 targeting. Results: Extracellular ENO1 promoted fibroblast activation protein expression through plasmin-mediated transforming growth factor-β (TGF-β) activation and induced a CAF-associated stromal phenotype marked by enhanced glycolytic activity and increased secretion of tumor-promoting cytokines in MM-BMSC co-cultures. HuL001 suppressed these ENO1-driven effects. HuL001-pretreated stromal cells also exhibited reduced tumor-supportive activity in a BTZ-resistant MM xenograft model. In addition, HuL001 combined with lenalidomide overcame BTZ resistance in MM. Conclusions: Extracellular ENO1 drives CAF-associated stromal reprogramming in the MM microenvironment through the ENO1/plasminogen/plasmin/TGF-β axis. Therapeutic targeting of extracellular ENO1 with HuL001 may disrupt these tumor-supportive stromal activities and help overcome drug resistance in MM.

Supplementary Figure from A Novel Enolase-1 Antibody Targets Multiple Interacting Players in the Tumor Microenvironment of Advanced Prostate Cancer

Protein expression of ABCC1 in MCF7 with ABCC1 overexpression.

Supplementary Figure from A Novel Enolase-1 Antibody Targets Multiple Interacting Players in the Tumor Microenvironment of Advanced Prostate Cancer