Galectin-1 (Gal-1) is a B-galactose-binding lectin; its expression level has been reported to correlate with tumor progression. Gal-1 is highly expressed in the invasive front of primary tumors and in the cancer cells of metastatic lesions in the lymph nodes of patients with oral squamous cell carcinoma. However, the molecular mechanism of Gal-1 in tumor metastasis is not completely clear. We found that increased Gal-1 expression is closely associated with its high levels of invasion in lung adenocarcinoma and oral squamous cell carcinoma cell lines. Knocking down Gal-1 with small interfering RNA in highly invasive cancer cells reduced their invasion levels. Moreover, the invasion ability of poorly invasive cancer cells was significantly increased after Gal-1 overexpression of Gal-1. Mechanism studies revealed that Gal-1 promoted tumor invasion mainly by up-regulating matrix metalloproteinase (MMP)-9 and MMP-2 and by reorganizing actin cytoskeleton. Gal-1 enhanced the activation of Cdc42, a small GTPase and member of the Rho family, thus increasing the number and length of filopodia on tumor cells. Furthermore, Gal-1-overexpressing cells had higher metastatic abilities in tail vein metastasis assays in vivo. We conclude that Gal-1 is involved in tumor invasion and metastasis by increasing MMP expression and reorganizing cytoskeletons in oral cancers and lung adenocarcinoma. (Mol Cancer Res 2009;7(3):311 -8)

S100A4 is a member of the S100 family of calcium-binding proteins that is directly involved in tumor metastasis. In the present study, we examined the potential role of S100A4 in metastasis in breast cancer and its relation with matrix metalloproteinase-13 (MMP-13). Analysis of 100 breast cancer specimens including 50 with and 50 without lymph node metastasis showed a significant upregulation of S100A4 and MMP-13 expression in metastatic breast cancer tissues. Positive immunoreactivity for S100A4 was associated with MMP-13 expression. Overexpression of S100A4 in the MDA-MB-231 breast cancer cell line upregulated MMP13 expression leading to increased cell migration and angiogenesis. SiRNA-mediated silencing of S100A4 downregulated MMP13 expression and suppressed cell migration and angiogenesis. Moreover, neutralization of MMP-13 activity with a specific antibody blocked cell migration and angiogenesis in MDA-MB-231/S100A4 cells. In vivo siRNA silencing of S100A4 significantly inhibited lung metastasis in transgenic mice. The present results suggest that the S100A4 gene may control the invasive potential of human breast cancer cells by modulating MMP-13 levels, thus regulating metastasis and angiogenesis in breast tumors. S100A4 could therefore be of value as a biomarker of breast cancer progression and a novel therapeutic target for human breast cancer treatment.

3005 Background: Arginase is secreted by myeloid-derived suppressor cells (MDSCs) and polymorphonuclear cells (PMNs) in the tumor microenvironment, depleting arginine, an amino acid required for T-cell activation and proliferation. CB-1158 is an oral small molecule inhibitor of arginase. CB-1158 reverses PMN- and MDSC-mediated suppression of T-cells in ex vivo human models, and increases plasma and tumor arginine levels in mouse syngeneic tumor models leading to increased pro-inflammatory markers and activated CD8 T-cells in the tumor. CB-1158 has single agent efficacy in mouse tumor models and synergistically enhances the antitumor efficacy of checkpoint inhibitors. Methods: This is an ongoing phase 1 study to evaluate safety and tolerability of CB-1158 as a monotherapy and in combination with anti-PD-1 in pts with solid tumors. Pharmacokinetics (PK), anti-tumor effects, and biomarkers, including plasma arginine, arginase activity, and effects on immune function in blood and in tumors will be evaluated. CB-1158 was administered BID orally in 28-day cycles. Escalating doses were administered to cohorts for safety evaluation. Additional pts were enrolled at dose levels determined to be safe to support biomarker objectives. Results: Nine pts have been enrolled across two monotherapy dose escalation cohorts (50 and 100 mg) and biomarker cohorts. CB-1158 was rapidly absorbed (Tmax = 4 h) and was cleared with a half-life of 6 h. At doses of 50 and 100 mg, steady-state plasma trough levels were 1.6 and 4.5 µM, sufficient to achieve > 90% arginase inhibition, and plasma arginine levels increased 2.4- and 4-fold, respectively. CB-1158 has been well tolerated with no DLTs or drug-related Grade 3 AEs. Dose escalation is ongoing and updated safety, PK and biomarker data will be presented. Conclusions: CB-1158 is a first-in-class inhibitor of the myeloid-derived immunosuppressive enzyme arginase. CB-1158 has been well tolerated and achieves on-target inhibition resulting in increases in plasma arginine, an amino acid required for T-cell immune responses. Clinical trial information: NCT02903914.