title: Sperm-associated antigen 9 (SPAG9) promotes the survival and tumor growth of triple-negative breast cancer cells.
abstract: Recently, we demonstrated the association of sperm-associated antigen 9 (SPAG9) expression with breast cancer. Among breast cancer, 15 % of the cancers are diagnosed as triple-negative breast cancers (TNBC) based on hormone receptor status and represent an important clinical challenge because of lack of effective available targeted therapy. Therefore, in the present investigation, plasmid-based small hairpin (small hairpin RNA (shRNA)) approach was used to ablate SPAG9 in aggressive breast cancer cell line model (MDA-MB-231) in order to understand the role of SPAG9 at molecular level in apoptosis, cell cycle, and epithelial-to-mesenchymal transition (EMT) signaling. Our data in MDA-MB-231 cells showed that ablation of SPAG9 resulted in membrane blebbing, increased mitochondrial membrane potential, DNA fragmentation, phosphatidyl serine surface expression, and caspase activation. SPAG9 depletion also resulted in cell cycle arrest in G0-G1 phase and induced cellular senescence. In addition, in in vitro and in vivo xenograft studies, ablation of SPAG9 resulted in upregulation of p21 along with pro-apoptotic molecules such as BAK, BAX, BIM, BID, NOXA, AIF, Cyto-C, PARP1, APAF1, Caspase 3, and Caspase 9 and epithelial marker, E-cadherin. Also, SPAG9-depleted cells showed downregulation of cyclin B1, cyclin D1, cyclin E, CDK1, CDK4, CDK6, BCL2, Bcl-xL, XIAP, cIAP2, MCL1, GRP78, SLUG, SNAIL, TWIST, vimentin, N-cadherin, MMP2, MMP3, MMP9, SMA, and β-catenin. Collectively, our data suggests that SPAG9 promotes tumor growth by inhibiting apoptosis, altering cell cycle, and enhancing EMT signaling in in vitro cells and in vivo mouse model. Hence, SPAG9 may be a potential novel target for therapeutic use in TNBC treatment.
authors.affiliation: Cancer Research Program, Cancer Microarray, Genes and Proteins Laboratory, National Institute of Immunology, Aruna Asaf Ali Marg, New Delhi, 110067, India.
authors.forename: Nirmala
authors.initials: N
authors.lastname: Jagadish
authors.affiliation: Cancer Research Program, Cancer Microarray, Genes and Proteins Laboratory, National Institute of Immunology, Aruna Asaf Ali Marg, New Delhi, 110067, India.
authors.forename: Namita
authors.initials: N
authors.lastname: Gupta
authors.affiliation: Cancer Research Program, Cancer Microarray, Genes and Proteins Laboratory, National Institute of Immunology, Aruna Asaf Ali Marg, New Delhi, 110067, India.
authors.forename: Sumit
authors.initials: S
authors.lastname: Agarwal
authors.affiliation: Cancer Research Program, Cancer Microarray, Genes and Proteins Laboratory, National Institute of Immunology, Aruna Asaf Ali Marg, New Delhi, 110067, India.
authors.forename: Deepak
authors.initials: D
authors.lastname: Parashar
authors.affiliation: Cancer Research Program, Cancer Microarray, Genes and Proteins Laboratory, National Institute of Immunology, Aruna Asaf Ali Marg, New Delhi, 110067, India.
authors.forename: Aditi
authors.initials: A
authors.lastname: Sharma
authors.affiliation: Cancer Research Program, Cancer Microarray, Genes and Proteins Laboratory, National Institute of Immunology, Aruna Asaf Ali Marg, New Delhi, 110067, India.
authors.forename: Rukhsar
authors.initials: R
authors.lastname: Fatima
authors.affiliation: Cancer Research Program, Cancer Microarray, Genes and Proteins Laboratory, National Institute of Immunology, Aruna Asaf Ali Marg, New Delhi, 110067, India.
authors.forename: Amos Prashant
authors.initials: AP
authors.lastname: Topno
authors.affiliation: Cancer Research Program, Cancer Microarray, Genes and Proteins Laboratory, National Institute of Immunology, Aruna Asaf Ali Marg, New Delhi, 110067, India.
authors.forename: Vikash
authors.initials: V
authors.lastname: Kumar
authors.affiliation: Cancer Research Program, Cancer Microarray, Genes and Proteins Laboratory, National Institute of Immunology, Aruna Asaf Ali Marg, New Delhi, 110067, India. anil@nii.res.in.
authors.forename: Anil
authors.initials: A
authors.lastname: Suri
mesh_terms: D048868:Adaptor Proteins, Signal Transducing / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D000818:Animals; D017209:Apoptosis; D015153:Blotting, Western; D049109:Cell Proliferation; D000091342:Endoplasmic Reticulum Chaperone BiP; D019084:Fluorescent Antibody Technique, Indirect; D006801:Humans; D007124:Immunoenzyme Techniques; D053078:Membrane Potential, Mitochondrial; D051379:Mice; D034741:RNA, Small Interfering / Q000235:genetics; D064726:Triple Negative Breast Neoplasms / Q000235:genetics / Q000378:metabolism / Q000473:pathology*; D014407:Tumor Cells, Cultured
chemical_list: D048868:Adaptor Proteins, Signal Transducing; D000091342:Endoplasmic Reticulum Chaperone BiP; C000717247:HSPA5 protein, human; C000717248:Hspa5 protein, mouse; D034741:RNA, Small Interfering; C111047:SPAG9 protein, human
keywords: Apoptosis; Cell growth; Cellular motility; SPAG9; Senescence; Triple-negative breast cancer; Tumor growth