Small interfering RNA-mediated down-regulation of SPAG9 inhibits cervical tumor growth

The Contributions of Cancer-Testis and Developmental Genes to the Pathogenesis of Keratinocyte Carcinomas

Simple Summary

In addition to mutations, ectopically-expressed genes are emerging as important contributors to cancer development. Efforts to characterize the expression patterns in cancers of gamete-restricted cancer-testis antigens and developmentally-restricted genes are underway, revealing these genes to be putative biomarkers and therapeutic targets for various malignancies. Basal cell carcinoma (BCC) and cutaneous squamous cell carcinoma (cSCC) are two highly-prevalent non-melanoma skin cancers that result in considerable burden on patients and our health system. To optimize disease prognostication and treatment, it is necessary to further classify the molecular complexity of these malignancies. This review describes the expression patterns and functions of cancer-testis antigens and developmentally-restricted genes in BCC and cSCC tumors. A large number of cancer-testis antigens and developmental genes exhibit substantial expression levels in BCC and cSCC. These genes have been shown to contribute to several aspects of cancer biology, including tumorigenesis, differentiation, invasion and responses to anti-cancer therapy.

Abstract

Keratinocyte carcinomas are among the most prevalent malignancies worldwide. Basal cell carcinoma (BCC) and cutaneous squamous cell carcinoma (cSCC) are the two cancers recognized as keratinocyte carcinomas. The standard of care for treating these cancers includes surgery and ablative therapies. However, in recent years, targeted therapies (e.g., cetuximab for cSCC and vismodegib/sonidegib for BCC) have been used to treat advanced disease as well as immunotherapy (e.g., cemiplimab). These treatments are expensive and have significant toxicities with objective response rates approaching ~50–65%. Hence, there is a need to dissect the molecular pathogenesis of these cancers to identify novel biomarkers and therapeutic targets to improve disease management. Several cancer-testis antigens (CTA) and developmental genes (including embryonic stem cell factors and fetal genes) are ectopically expressed in BCC and cSCC. When ectopically expressed in malignant tissues, functions of these genes may be recaptured to promote tumorigenesis. CTAs and developmental genes are emerging as important players in the pathogenesis of BCC and cSCC, positioning themselves as attractive candidate biomarkers and therapeutic targets requiring rigorous testing. Herein, we review the current research and offer perspectives on the contributions of CTAs and developmental genes to the pathogenesis of keratinocyte carcinomas.

Overexpression of laminin-5 gamma-2 promotes tumorigenesis of pancreatic ductal adenocarcinoma through EGFR/ERK1/2/AKT/mTOR cascade

Pancreatic ductal adenocarcinoma (PDAC) is correlated with poor outcomes because of limited therapeutic options. Laminin-5 gamma-2 (LAMC2) plays a critical role in key biological processes. However, the detailed molecular mechanism and potential roles of LAMC2 in PDAC stay unexplored. The present study examines the essential role and molecular mechanisms of LAMC2 in the tumorigenesis of PDAC. Here, we identified that LAMC2 is significantly upregulated in microarray cohorts and TCGA RNA sequencing data of PDAC patients compared to non-cancerous/normal tissues. Patients with higher transcript levels of LAMC2 were correlated with clinical stages; dismal overall, as well as, disease-free survival. Additionally, we confirmed significant upregulation of LAMC2 in a panel of PDAC cell lines and PDAC tumor specimens in contrast to normal pancreatic tissues and cells. Inhibition of LAMC2 significantly decreased cell growth, clonogenic ability, migration and invasion of PDAC cells, and tumor growth in the PDAC xenograft model. Mechanistically, silencing of LAMC2 suppressed expression of ZEB1, SNAIL, N-cadherin (CDH2), vimentin (VIM), and induced E-cadherin (CDH1) expression leading to a reversal of mesenchymal to an epithelial phenotype. Interestingly, co-immunoprecipitation experiments demonstrated LAMC2 interaction with epidermal growth factor receptor (EGFR). Further, stable knockdown of LAMC2 inhibited phosphorylation of EGFR, ERK1/2, AKT, mTOR, and P70S6 kinase signaling cascade in PDAC cells. Altogether, our findings suggest that silencing of LAMC2 inhibited PDAC tumorigenesis and metastasis through repression of epithelial-mesenchymal transition and modulation of EGFR/ERK1/2/AKT/mTOR axis and could be a potential diagnostic, prognostic, and therapeutic target for PDAC.

Oncolytic adenovirus carrying SPAG9-shRNA enhanced the efficacy of docetaxel for advanced prostate cancer

BACKGROUND

Sperm-associated antigen 9 (SPAG9) is closely related to the growth and metastasis of advanced prostate cancer. Docetaxel (DTX) is the gold standard for chemotherapy of prostate cancer, but its side effects decrease the life quality of patients. Therefore, it is urgent to develop combination therapy to increase chemotherapy efficacy for advanced prostate cancer.

METHODS

Oncolytic adenovirus carrying a short hairpin RNA (shRNA) targeting SPAG9 (ZD55-shSPAG9) was applied alone or in combination with docetaxel in prostate cancer cells. Cells were analyzed by cell counting kit-8, Hocehst-33258, transwell and western blot analysis. For in vivo experiments, nude mice were loaded with prostate cancer cells.

RESULTS

ZD55-shSPAG9 effectively silenced the expression of SPAG9 in prostate cancer cells in vitro and in vivo. The replication of ZD55-shSPAG9 in prostate cancer cells was not affected by docetaxel, but the combined use of ZD55-shSAPAG9 and docetaxel has a better inhibitory effect on tumor growth and invasion in vitro and in vivo.

CONCLUSIONS

Our study showed that the combined use of ZD55-shSPAG9 and docetaxel may be a new approach to the treatment of advanced prostate cancer.

Sperm associated antigen 9 promotes oncogenic KSHV-encoded interferon regulatory factor-induced cellular transformation and angiogenesis by activating the JNK/VEGFA pathway

Kaposi's sarcoma (KS), caused by Kaposi's sarcoma-associated herpesvirus (KSHV), is a highly angioproliferative disseminated tumor of endothelial cells commonly found in AIDS patients. We have recently shown that KSHV-encoded viral interferon regulatory factor 1 (vIRF1) mediates KSHV-induced cell motility (PLoS Pathog. 2019 Jan 30;15(1):e1007578). However, the role of vIRF1 in KSHV-induced cellular transformation and angiogenesis remains unknown. Here, we show that vIRF1 promotes angiogenesis by upregulating sperm associated antigen 9 (SPAG9) using two in vivo angiogenesis models including the chick chorioallantoic membrane assay (CAM) and the matrigel plug angiogenesis assay in mice. Mechanistically, vIRF1 interacts with transcription factor Lef1 to promote SPAG9 transcription. vIRF1-induced SPAG9 promotes the interaction of mitogen-activated protein kinase kinase 4 (MKK4) with JNK1/2 to increase their phosphorylation, resulting in enhanced VEGFA expression, angiogenesis, cell proliferation and migration. Finally, genetic deletion of ORF-K9 from KSHV genome abolishes KSHV-induced cellular transformation and impairs angiogenesis. Our results reveal that vIRF1 transcriptionally activates SPAG9 expression to promote angiogenesis and tumorigenesis via activating JNK/VEGFA signaling. These novel findings define the mechanism of KSHV induction of the SPAG9/JNK/VEGFA pathway and establish the scientific basis for targeting this pathway for treating KSHV-associated cancers.

A negative feedback loop between JNK-associated leucine zipper protein and TGF-β1 regulates kidney fibrosis

Renal fibrosis is controlled by profibrotic and antifibrotic forces. Exploring anti-fibrosis factors and mechanisms is an attractive strategy to prevent organ failure. Here we identified the JNK-associated leucine zipper protein (JLP) as a potential endogenous antifibrotic factor. JLP, predominantly expressed in renal tubular epithelial cells (TECs) in normal human or mouse kidneys, was downregulated in fibrotic kidneys. Jlp deficiency resulted in more severe renal fibrosis in unilateral ureteral obstruction (UUO) mice, while renal fibrosis resistance was observed in TECs-specific transgenic Jlp mice. JLP executes its protective role in renal fibrosis via negatively regulating TGF-β1 expression and autophagy, and the profibrotic effects of ECM production, epithelial-to-mesenchymal transition (EMT), apoptosis and cell cycle arrest in TECs. We further found that TGF-β1 and FGF-2 could negatively regulate the expression of JLP. Our study suggests that JLP plays a central role in renal fibrosis via its negative crosstalk with the profibrotic factor, TGF-β1.

Qi Yan et al. find that JNK-associated leucine zipper protein (Jlp) counteracts the profibrotic effects of TGF-β1 and autophagy on renal tubular epithelial cells and that TGF-β1 and FGF-2 can negatively regulate the expression of Jlp. These findings provide insights into the role of Jlp in kidney fibrosis.

The potential immune-eliciting cancer testis antigens in colorectal cancer

The identification of cancer testis antigens (CTAs) has been an important finding in the search of potential targets for cancer immunotherapy. CTA is one of the subfamilies of the large tumor-associated antigens groups. It is aberrantly expressed in various types of human tumors but is absent in normal tissues except for the testis and placenta. This CTAs-restricted pattern of expression in human malignancies together with its potential immunogenic properties, has stirred the interest of many researchers to use CTAs as one of the ideal targets in cancer immunotherapy. To date, multiple studies have shown that CTAs-based vaccines can elicit clinical and immunological responses in different tumors, including colorectal cancer (CRC). This review details our current understanding of CTAs and CRC in regard to the expression and immunological responses as well as some of the critical hurdles in CTAs-based immunotherapy.

Sperm-associated antigen 9 is upregulated in hepatocellular carcinoma tissue and enhances QGY cell proliferation and invasion in vitro

The incidence and mortality rates of hepatocellular carcinoma (HCC) are higher in China compared with in other countries. Further research is required in order to improve the diagnosis and treatment of HCC. Sperm-associated antigen 9 (SPAG9) protein has been revealed to serve an important function in cancer progression; however, the underlying mechanisms remain to be elucidated. The present study investigated the expression level of SPAG9 in HCC tissues using quantitative-polymerase chain reaction, immunohistochemistry and western blotting, and the results demonstrated that SPAG9 was overexpressed in HCC tissues compared with the adjacent non-cancerous tissues. To explore the potential mechanisms underlying SPAG9 in HCC, the effect of SPAG9 on cell proliferation, cell cycle, migration and invasion capacities were investigated in the QGY HCC cell line by RNA interference. It was revealed that inhibition of SPAG9 mRNA in QGY cells significantly inhibited the expression level of SPAG9 compared with the control. Depletion of SPAG9 expression decreased cell proliferation (P<0.01) and increased the percentage of cells in the G₁/G₂ cell cycle phase. The percentage of cells in the S phase was decreased, and cell migration and invasion capabilities in vitro were reduced (P<0.01). In summary, the results of the present study suggested that SPAG9 was upregulated in HCC and may serve an important function in cancer cell proliferation, differentiation and invasion. Whether SPAG9 is a potential diagnostic marker and therapeutic target of human HCC requires additional study.

SPAG9 is overexpressed in osteosarcoma, and regulates cell proliferation and invasion through regulation of JunD

Sperm-associated antigen 9 (SPAG9) is a recently characterized oncoprotein that is considered to be involved in several forms of malignant tumor. However, its biological function and expression pattern in human osteosarcoma have not yet been elucidated. In the present study, SPAG9 expression was analyzed in 58 cases of human osteosarcoma by immunohistochemistry. The results demonstrated that SPAG9 was overexpressed in 63.8% (37/58) of osteosarcoma tissues, while normal bone tissues exhibited negative SPAG9 expression. SPAG9 small interfering RNA was employed in the U2OS cell line, which has high endogenous expression, and SPAG9 transfection was performed in the MG63 cell line, which has low endogenous expression. MTT and Matrigel invasion assays demonstrated that SPAG-9-knockdown significantly reduced U2OS cell invasion and proliferation, while SPAG9 transfection enhanced MG63 cell proliferation and invasion. Furthermore, it was observed that SPAG9 positively regulated cyclin D1, phosphorylated-c-Jun NH2-terminal kinase (JNK) and JunD expression. Treatment with the JNK inhibitor, SP600125, abolished the upregulatory effect of SPAG9 on JunD. Taken together, the present study identified SPAG9 as a critical oncoprotein involved in osteosarcoma proliferation and invasion, possibly functioning through JNK-JunD signaling.

SPAG9 is involved in hepatocarcinoma cell migration and invasion via modulation of ELK1 expression

Background

Sperm-associated antigen 9 (SPAG9) is upregulated in several malignancies and its overexpression is positively correlated with cancer cell malignancies. However, the specific biological roles of SPAG9 in hepatocellular carcinoma (HCC) are less understood.

Methods

We analyzed SPAG9 and ETS-like gene 1, tyrosine kinase (ELK1) expression in 50 paired HCC specimens and adjacent noncancerous liver specimens using immunohistochemistry. SPAG9 small interfering RNA (siRNA) was used to knockdown SPAG9 expression in HCCLM3 and HuH7 cell lines. We used plasmids to upregulate ELK1 expression and siRNA to downregulate ELK1 expression in HuH7 cells. Quantitative real-time polymerase chain reaction and Western blot were used to evaluate the expression of SPAG9 and ELK1 at the mRNA and protein level, respectively. Wound healing, matrigel migration, and invasion analyses were performed to determine the effect of SPAG9 and ELK1 on HCC metastasis.

Results

SPAG9 and ELK1 were overexpressed in HCC tissue specimens and their expressions were higher in HCCLM3 and HuH7 cells compared to the low-metastatic HepG2 cells. Overexpression of SPAG9 was positively associated with tumor-node-metastasis staging (P=0.032), metastasis parameters (P=0.018) of HCC patients, and ELK1 expression (r=0.422, P<0.001) in HCC tissue specimens. In addition, knockdown of SPAG9 in HCCLM3 and HuH7 cells using siRNA significantly suppressed cell migration and invasion. Furthermore, we observed inhibition of ELK1 expression and p38 signaling. However, ELK1 overexpression reversed the inhibitory effects of SPAG9 siRNA on HCC cell metastasis and ELK1 depletion inhibited HuH7 cell migration and invasion.

Conclusion

SPAG9 overexpression was positively correlated with HCC metastasis and SPAG9-induced migration and invasion were partially dependent on ELK1 expression in HCC cell lines. These results suggest that SPAG9 may be a potential anti-metastasis target effective in HCC therapy.

MicroRNA-200a-3p suppresses tumor proliferation and induces apoptosis by targeting SPAG9 in renal cell carcinoma

Sperm-associated antigen 9(SPAG9), as a well-recognized oncogene protein, has a critical effect on renal cell carcinoma (RCC) progression. Our study tried to explore the mediator of miR-200a-3p, a tumor suppressing miRNA on SPAG9 expression and renal cell proliferation and apoptosis. We found the expression of miR-200a-3p was significantly lower in RCC specimens. Based on in vitro assays, we found miR-200a-3p significantly inhibit cancer cell proliferation by inducing apoptosis. In addition, our study uncovered that miR-200a-3p directly regulates oncogenic SPAG9 in 786-O and ACHN cells. Silencing of SPAG9 resulted in significantly decreased in the growth and the cell cycle of the renal cancer cell lines. Understanding of oncogenic SPAG9 regulated by miR-200a-3p might be beneficial to reveal new therapeutic targets for RCC.

Targeting cancer testis antigens for biomarkers and immunotherapy in colorectal cancer: Current status and challenges

Colorectal cancer ranks third among the estimated cancer cases and cancer related mortalities in United States in 2014. Early detection and efficient therapy remains a significant clinical challenge for this disease. Therefore, there is a need to identify novel tumor associated molecules to target for biomarker development and immunotherapy. In this regard, cancer testis antigens have emerged as a potential targets for developing novel clinical biomarkers and immunotherapy for various malignancies. These germ cell specific proteins exhibit aberrant expression in cancer cells and contribute in tumorigenesis. Owing to their unique expression profile and immunogenicity in cancer patients, cancer testis antigens are clinically referred as the most promising tumor associated antigens. Several cancer testis antigens have been studied in colorectal cancer but none of them could be used in clinical practice. This review is an attempt to address the promising cancer testis antigens in colorectal cancer and their possible clinical implications as biomarkers and immunotherapeutic targets with particular focus on challenges and future interventions.

SPAG9 controls the cell motility, invasion and angiogenesis of human osteosarcoma cells

Sperm-associated antigen 9 (SPAG9) is an oncoprotein involved in the progression of various human malignancies; however, its role in osteosarcoma (OS) remains poorly evaluated. The present study used Matrigel™ cell migration and invasion assays, tube formation assay, Cell Counting kit-8, quantitative polymerase chain reaction, western blotting, and enzyme-linked immunosorbent assay to investigate the role of SPAG9 in OS cell motility, invasion and angiogenesis. The results of the present study demonstrated that SPAG9 expression was upregulated in OS tissues, as compared with adjacent normal tissues, and knockdown of SPAG9 in an OS cell line inhibited cell motility and invasion via inactivation of metalloproteinase (MMP)-2 and MMP-9. Furthermore, the present study demonstrated that silencing of SPAG9 in OS cells inhibited tube formation, the proliferation of human umbilical vascular endothelial cells, and suppressed vascular endothelial growth factor (VEGF) expression and secretion, contributing to a reduction in angiogenesis. The results of the present study indicated that SPAG9 may be an important regulator in OS and may be involved in metastasis. Therefore SPAG9 may be a promising target for the treatment of metastatic OS.

Sperm-associated antigen 9 overexpression correlates with poor prognosis and insensitive to Taxol treatment in breast cancer

Sperm-associated antigen 9 (SPAG9) has been reported to express in several cancers and have clinical significance. Using immunohistochemistry, we found that there was a strong association among SPAG9 expression and tumor size, TNM stage, histological grade, lymph node metastasis, and recurrence. It suggested that SPAG9-elevated expression was an independently prognostic indicator for both OS and DFS. Furthermore, the selected treatment of chemotherapy with Taxol/non-Taxol significantly affects OS and DFS. To sum up, SPAG9-elevated expression contributes to malignant behavior and poor prognosis of breast cancer and may support a potential indicator in treatment selection.

Overexpression of SPAG9 in human gastric cancer is correlated with poor prognosis

Sperm associated antigen 9 (SPAG9) protein has been found to play an important role in cancer progression but the involved mechanisms are still obscure. Its clinical significance in human gastric cancers remains unexplored. In the present study, SPAG9 expression was analyzed in 147 gastric cancer specimens. We observed weak staining in normal gastric mucosa and positive staining in 65 out of 147 (44.2 %) cancer samples. Overexpression of SPAG9 correlated with local invasion (p = 0.0101), lymph node metastasis (p = 0.0488), TNM stage (p = 0.0002), and relapse (p = 0.0018). Importantly, SPAG9 overexpression correlated with poor overall survival (p = 0.0008). Furthermore, we performed siRNA knockdown of SPAG9 in HGC-27 cells with high endogenous expression and transfected SPAG9 plasmid in SGC-7901 cell line with low endogenous level. SPAG9 overexpression promoted while its depletion inhibited cell proliferation, cell cycle transition, and invasive cell growth. SPAG9 overxpression also increased chemoresistance to 5--fluorouracil (5-FU) in SGC-7901 cells. Further analysis showed that SPAG9 knockdown downregulated and its overexpression upregulated cyclin D1, MMP9, and p-p38 expression. In conclusion, SPAG9 overexpression in gastric cancer correlates with poor prognosis and contributes to gastric cancer cell proliferation, invasion, and chemoresistance. SPAG9 promotes gastric cancer invasion, possibly through p38-MMP9 signaling pathways.

SPAG9 expression is increased in human prostate cancer and promotes cell motility, invasion and angiogenesis in vitro

Sperm-associated antigen 9 (SPAG9) is a recently characterized oncoprotein involved in the progression of several human malignancies. To elucidate the role of SPAG9 in the development of human prostate cancer (PCa), tissue microarray (TMA) and immunohistochemistry were used to detect the clinical relevance of SPAG9 in PCa tissues. We found that SPAG9 expression was increased in the PCa tissues when compared with the level in the tumor adjacent normal prostate tissues, and increased SPAG9 staining was significantly correlated with TNM stage and tumor grade. We also examined prostate cancer cell motility, invasion and angiogenesis ability following reduced SPAG9 expression by siRNA. Our data showed that knockdown of SPAG9 in prostate cancer cell lines inhibited cell motility and invasion due to the inactivation of metalloproteinase-2 (MMP‑2)/MMP-9 by upregulation of tissue inhibitor of metalloproteinase-1 (TIMP-1)/TIMP-2. Furthermore, downregulation of vascular endothelial growth factor (VEGF) secretion greatly contributed to the reduced ability of angiogenesis. Our data indicate that SPAG9 expression is significantly increased in PCa and it may be involved in the process of prostate cancer cell motility, migration and angiogenesis.

Overexpression of SPAG9 correlates with poor prognosis and tumor progression in hepatocellular carcinoma

Sperm-associated antigen 9 (SPAG9) was reported as a novel biomarker for several cancers and associated with the malignant behavior of cancer cells. However, its expression pattern and biological role in human hepatocellular carcinoma (HCC) have not been reported. In the present study, we analyzed SPAG9 expression in human HCC tissues by immunohistochemistry and found that SPAG9 overexpression is correlated with tumor stage (p < 0.001), tumor multiplicity (p = 0.019), tumor size (p = 0.034), AFP levels (p = 0.006), and tumor relapse (p = 0.0017). Furthermore, SPAG9 overexpression is correlated with poor overall survival (p < 0.001) and relapse-free survival (p = 0.002). Transfection of SPAG9 small interfering RNA (siRNA) was performed in Bel-7402 cell line. Colony formation and MTT showed that SPAG9 siRNA knockdown inhibited HCC cell proliferation. We also found that SPAG9 depletion could increase cell apoptosis. In addition, the level of cyclin D1 and cyclin E protein expression was downregulated after siRNA treatment. In conclusion, SPAG9 is overexpressed in human HCC and serves as a prognostic marker. SPAG9 contributes to cancer cell growth through regulation of cyclin proteins.

Sperm‑associated antigen 9 promotes astrocytoma cell invasion through the upregulation of podocalyxin

Podocalyxin (PODXL) has been found to increase the aggressive phenotype of a number of cancers, including astrocytoma. In addition, the progression of astrocytoma has been associated with sperm‑associated antigen 9 (SPAG9), a recently characterized oncoprotein. In the present study, the association between SPAG9 and PODXL in human astrocytoma invasion and the underlying mechanisms were investigated for the first time, to the best of our knowledge. Overexpression and knockdown of SPAG9 were performed in SW1783 (grade III astrocytoma) and U87 (grade IV astrocytoma; glioblastoma) cells, respectively. PODXL expression at both the mRNA and the protein level, as well as the PODXL gene promoter activity, were significantly increased and decreased in parallel with the overexpression and knockdown of SPAG9 in astrocytoma cells; these effects were blocked by the selective c‑Jun N‑terminal kinase (JNK) inhibitor SP600125 (5 µM) and restored by the JNK agonist anisomycin (25 ng/ml), respectively. SPAG9 overexpression significantly increased cell invasion and matrix metalloproteinase‑9 (MMP‑9) expression in SW1783 cells, and this effect was reversed by knockdown of PODXL. In U87 cells, knockdown of SPAG9 markedly decreased cell invasion and MMP‑9 expression, which was completely restored by overexpression of PODXL. In conclusion, it was demonstrated in the present study that SPAG9 upregulates PODXL expression in human astrocytoma cells at the PODXL gene promoter/transcriptional level through a JNK‑dependent mechanism and that PODXL is a critical mediator of the promoting effect of SPAG9 on astrocytoma cell invasion, possibly through upregulation of MMP‑9 expression. This study provides novel insights into the molecular mechanisms involved in astrocytoma invasion.

SPAG9 is overexpressed in human prostate cancer and promotes cancer cell proliferation

Sperm-associated antigen 9 (SPAG9) was recently reported to be overexpressed in several cancers and associated with the malignant behavior of cancer cells. However, the expression pattern of SPAG9 and its clinical significance in human prostate cancer have not been reported. In the present study, we analyzed SPAG9 expression in human prostate cancer tissues by immunohistochemistry and found that SPAG9 was overexpressed in 36.5 % of prostate cancer specimens. There was a significant association between SPAG9 overexpression and tumor stage (p = 0.0020) and Gleason score (p = 0.0377). Transfection of SPAG9 plasmid was performed in PC-3 cell line and siRNA knockdown was carried out in DU145 cells. Colony formation and MTT showed that SPAG9 overexpression promoted while siRNA knockdown inhibited prostate cancer cell proliferation. In addition, we found that SPAG9 could regulate cyclin D1 and cyclin E protein expression. In conclusion, SPAG9 is overexpressed in human prostate cancers and contributes to prostate cancer cell growth, possibly through cyclin protein regulation.

Down regulation of SPAG9 reduces growth and invasive potential of triple-negative breast cancer cells: possible implications in targeted therapy

BACKGROUND

Recently, we reported an association of a novel cancer testis (CT) antigen, sperm-associated antigen 9 (SPAG9) expression in breast cancer clinical samples, indicating its potential role in carcinogenesis. Around 15% breast cancers are designated as triple-negative for which treatment modalities are limited. Therefore, in the present study, we assessed the role of SPAG9 in triple-negative breast cancer cells.

METHODS

SPAG9 mRNA and protein expression was investigated in various breast cancer cells of different hormone receptor status and different subtypes by employing reverse transcriptase-polymerase chain reaction (RT-PCR), real time PCR, Western blotting, indirect immunofluorescence (IIF) and fluorescence activated cell sorting (FACS). Employing plasmid-based small interfering RNA (siRNA) approach, knockdown of SPAG9 was carried out in triple-negative breast cancer cells, MDA-MB-231, to assess its role on various malignant properties in vitro and in vivo.

RESULTS

SPAG9 mRNA and protein expression was detected in all breast cancer cells. Further, IIF results showed that SPAG9 was predominantly localized in the cytoplasm of breast cancer cells. FACS analysis revealed distinct SPAG9 surface localization in breast cancer cells. Gene silencing of SPAG9 resulted in significant reduction in cellular proliferation, colony forming ability, migration, invasion and cellular motility of MDA-MB-231 cells. Further, ablation of SPAG9 expression resulted in reduction in the tumor growth of human breast cancer xenograft in nude mice in vivo.

CONCLUSIONS

In summary, our data indicated that down regulation of SPAG9 reduces growth and invasive potential of triple-negative breast cancer cells, suggesting that SPAG9 may be a potential target for therapeutic use.

Gene silencing of A-kinase anchor protein 4 inhibits cervical cancer growth in vitro and in vivo

Earlier, we reported an association of A-kinase anchor protein 4 (AKAP4) expression in cervical cancer patient specimens, indicating its implications as an immunotherapeutic target. In this study, we investigated the possible role of AKAP4 in cervical carcinogenesis. AKAP4 messenger RNA and protein expression was assessed in four cervical cancer cell line models, C-33A, CaSki, HeLa and SiHa. Gene silencing approach was employed to investigate the potential role of AKAP4 in cellular growth, proliferation, colony-forming ability, migration and invasion in aggressive squamous cell carcinoma cells (SiHa). Further, the effect of downregulation of AKAP4 on tumor growth was examined in the cervical cancer xenograft model in nude mice. Our data clearly indicated that AKAP4 was expressed in all cervical cancer cells at the gene and protein level. We also observed distinct cytoplasmic and surface localization by indirect immunofluorescence and flow cytometry, respectively. Ablation of AKAP4 protein caused significant inhibition in cellular proliferation, colony-forming ability, migration and invasion ability of SiHa cells. Further, gene silencing of AKAP4 also resulted in reduced tumor growth in nude mice in vivo. Collectively, AKAP4 surface localization and its significant association with malignant properties of cervical cancer cells imply its clinical utility as an immunotherapeutic target.

Clinical significance and biological roles of SPAG9 overexpression in non-small cell lung cancer

To investigate the expression pattern of SPAG9 protein and its clinical significance in human non-small cell lung cancer (NSCLC). We checked a panel of 120 NSCLC tissues and 20 corresponding normal lung tissues by immumohistochemistry. We observed negative staining in the normal bronchial epithelia and positive staining of SPAG9 in 63 out of 120 (52.5%) NSCLC samples. Overexpression of SPAG9 correlated with poor tumor differentiation (p = 0.002), advanced p-TNM stage (p = 0.0001), nodal metastasis (p = 0.0061) and poor overall survival (p = 0.0001). We silenced SPAG9 gene in A549 and H1299 cells by specific siRNA and found that silencing SPAG9 expression inhibited cell growth and invasion. In addition, the protein and mRNA levels of MMP9 were also down-regulated in SPAG9 knocked down cells. Further research demonstrated SPAG9 depletion could inhibit the activity of p-JNK. In conclusion, SPAG9 might act as an important promoter in lung cancer progression and invasion via MMP9 regulation and JNK activation.

SPAG9 is overexpressed in human astrocytoma and promotes cell proliferation and invasion

Sperm-associated antigen 9 (SPAG9) is a recently characterized oncoprotein involved in the progression of several human malignancies. The present study aims to investigate the expression pattern and biological roles of SPAG9 protein in human astrocytoma. SPAG9 expression was analyzed in 105 astrocytoma specimens by immunohistochemistry. We observed negative staining in normal astrocytes and positive staining of SPAG9 in 63 out of 105 (60 %) astrocytoma samples. Overexpression of SPAG9 correlated with tumor grade (p < 0.001). Small interfering RNA knockdown was performed in U251 and U87 cell lines with relatively high SPAG9 expression. Using methylthiazolyldiphenyl-tetrazolium bromide assay and Matrigel invasion assay, we were able to show that SPAG9 depletion in astrocytoma cell lines inhibited cell proliferation and invasion in both cell lines. In addition, mRNA and protein levels of matrix metallopeptidase 9 (MMP9) were downregulated, while the levels of tissue inhibitor of metalloproteinase 1 (TIMP1) and TIMP2 were not changed, indicating that SPAG9 might regulate invasion through MMP9. In conclusion, SPAG9 serves as an important oncoprotein in human astrocytoma by regulating cell proliferation and invasion.

Sperm-associated antigen 9 is a novel biomarker for colorectal cancer and is involved in tumor growth and tumorigenicity

Colorectal cancer (CRC) is the second most common tumor in developed countries. The present study was undertaken to determine the expression of the sperm-associated antigen 9 gene (SPAG9) as a possible biomarker in CRC, to investigate its correlation with humoral immune response and different stages and grades in CRC patients, and to explore its possible role in colon tumorigenesis in vitro and in an in vivo mouse model. SPAG9 expression was determined by RT-PCR, in situ RNA hybridization, and immunohistochemistry. Humoral response against SPAG9 was detected by enzyme-linked immunosorbent assay and Western blotting. SPAG9 gene silencing was performed using plasmid-based small interfering RNA to study various malignant properties of colon cancer cells in vitro and in vivo. The majority of CRC patients showed SPAG9 expression and generated humoral response. There was a close relationship between SPAG9 protein expression and humoral immune response in the majority of early-stage CRC patients, indicating that anti-SPAG9 antibodies could be a novel serum biomarker for early diagnosis. The down-regulation of SPAG9 (mediated by small interfering RNA) inhibited malignant properties in in vitro and significantly suppressed tumor growth in vivo. These findings collectively suggest that SPAG9 may have a role in tumor development and early spread and thus could serve as a novel target for early detection and for cancer immunotherapy.