Galectin-1 suppression delineates a new therapeutic strategy for myeloma-induced angiogenesis

Galectin-1 (Gal-1) is a lectin, involved in several processes related to cancer, including immunosuppression, angiogenesis, hypoxia, and metastases. Actually, the Gal-1 expression profile in multiple myeloma (MM) and its pathophysiological role in MMinduced angiogenesis and tumoral growth is unknown. Firstly, we found that Gal-1 was expressed by malignant plasma cells in MM patients and that its expression was up-regulated upon hypoxic treatment (1% of O2). Moreover the stable knock-down of Hypoxia Inducible Factor-1 (HIF-1) in MM cells significantly downregulated Gal-1 expression. Thereafter, we performed Gal-1 inhibition by lentivirus shRNA anti-Gal-1 in human myeloma cell lines (HMCLs) showing that its suppression did not affect cell proliferation and survival but modified their transcriptional profiles either in hypoxia or hypoxia condition. Interestingly pro-angiogenic genes including MMP9 and CCL2 were downregulated and those anti-angiogenic SEMA3A and CXCL10 were up-regulated by Gal-1 inhibition in MM cells. Data were also validated by Real time PCR and at protein level. Consistently we found that Gal-1 suppression in MM cells significantly decreased their pro-angiogenic proprieties by an in vitro assay. These evidences were confirmed in mice injected either subcutaneously or intratibially with HMCLs carrying a stable infection with shRNA anti-inhibition of Gal-1 or with the control vector cell line. Gal-1 suppression in both models showed a significant reduction in the tumoral burden and microvascular density compared to the control mice. Moreover, Gal-1 suppression induced smaller lytic lesions on x-ray in the intratibially model. Overall, our data indicate that Gal-1 is a new potential therapeutic target in MM.

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Storti P, Marchica V, Airoldi I, Donofrio G, Fiorini E, Ferri V, Guasco D, Todoerti K, Silbermann R, Anderson JL, Zhao W, Agnelli L, Bolzoni M, Martella E, Mancini C, Campanini N, Noonan DM, Petronini PG, Neri A, Aversa F, Roodman GD, Giuliani N