Gasdermin-B promotes invasion and metastasis in breast cancer cells

Gasdermin B (GSDMB) belongs to the Gasdermin protein family that comprises four members (GSDMA-D). Gasdermin B expression has been detected in some tumor types such as hepatocarcinomas, gastric and cervix cancers; and its overexpression has been related to tumor progression. At least four splicing isoforms of GSDMB have been identified, which may play differential roles in cancer. However, the implication of GSDMB in carcinogenesis and tumor progression is not well understood. Here, we uncover for the first time the functional implication of GSDMB in breast cancer. Our data shows that high levels of GSDMB expression is correlated with reduced survival and increased metastasis in breast cancer patients included in an expression dataset (>1,000 cases). We demonstrate that GSDMB is upregulated in breast carcinomas compared to normal breast tissue, being the isoform 2 (GSDMB-2) the most differentially expressed. In order to evaluate the functional role of GSDMB in breast cancer two GSDMB isoforms were studied (GSDMB-1 and GSDMB-2). The overexpression of both isoforms in the MCF7 breast carcinoma cell line promotes cell motility and invasion, while its silencing in HCC1954 breast carcinoma cells decreases the migratory and invasive phenotype. Importantly, we demonstrate that both isoforms have a differential role on the activation of Rac-1 and Cdc-42 Rho-GTPases. Moreover, our data support that GSMDB-2 induces a pro-tumorigenic and pro-metastatic behavior in mouse xenograft models as compared to GSDMB-1. Finally, we observed that although both GSDMB isoforms interact in vitro with the chaperone Hsp90, only the GSDMB-2 isoform relies on this chaperone for its stability. Taken together, our results provide for the first time evidences that GSDMB-2 induces invasion, tumor progression and metastasis in MCF7 cells and that GSDMB can be considered as a new potential prognostic marker in breast cancerThis work was supported by grants from the Spanish Ministry of Science and Innovation, MICINN (SAF2007-63075 and SAF2010-20175), AVON Foundation 2012, Comunidad de Madrid (S2010/BMD-2302), AECC network 2011, Instituto de Salud Carlos III (ISCIII) (PI13_00132) to GMB and Breast Network from ISCIII RD12036/0007 to AC. MHR has been funded by a predoctoral contract associated to SAF2007-63075 and now has a postdoc contract from S2010/BMD- 23. DS and PGS are funded by postdoc contracts from the AECC Scientific Foundation, AM is funded by a predoctoral fellowship from MECD; ACM is funded by ISCIII RD12036/0007. Dr HP’s work is supported by the Melanoma Research Alliance, Pediatric Oncology Experimental Therapeutics Investigators Consortium, The Nancy C. and Daniel P. Paduano Foundation, The Manning Foundation, NCI (U01 CA169538, RO1 CA169416-01) and the DoD (BC123187, BC12198