Identification of new TSGA10 transcript variants in human testis with conserved regulatory RNA elements in 5'untranslated region and distinct expression in breast cancer

Exploring TSGA10 Function: A Crosstalk or Controlling Mechanism in the Signaling Pathway of Carcinogenesis?

Cancer-specific antigens have been a significant area of focus in cancer treatment since their discovery in the mid-twentieth century. Cancer germline antigens are a class of antigens specifically overexpressed in germline tissues and cancer cells. Among these, TSGA10 (testis-specific gene antigen 10) is of great interest because of its crucial impact on cancer progression. Early studies explored TSGA10 expression in a variety of cancer types. More recent studies revealed that TSGA10 can suppress tumor progression by blocking cancer cell metabolism, angiogenesis, and metastasis. An open question regarding the TSGA10 is why cancer cells must express a protein that prevents their progression. To answer this question, we conducted a comprehensive review to engage the TSGA10 in the context of the current understanding of "malignant transformation". This review demonstrated that TSGA10 expression level in cancer cells depends on the cancer stage across malignant transformation. In addition, we evaluated how TSGA10 expression can prevent the "cancer hallmarks". Given this information, TSGA10 can be of great interest in developing effective targeted anti-cancer therapies.

Identification of TSGA10 and GGNBP2 splicing variants in 5' untranslated region with distinct expression profiles in brain tumor samples

Introduction

Brain tumors (BTs) are perceived as one of the most common malignancies among children. The specific regulation of each gene can play a critical role in cancer progression. The present study aimed to determine the transcripts of the TSGA10 and GGNBP2 genes, considering the alternative 5'UTR region, and investigating the expression of these different transcripts in BTs.

Material and methods

Public data on brain tumor microarray datasets in GEO were analyzed with R software to evaluate the expression levels of TSGA10 and GGNBP2 genes (the Pheatmap package in R was also used to plot DEGs in a heat map). In addition, to validate our in-silico data analysis, RT-PCR was performed to determine the splicing variants of TSGA10 and GGNBP2 genes in testis and brain tumor samples. The expression levels of splice variants of these genes were analyzed in 30 brain tumor samples and two testicular tissue samples as a positive control.

Results

In silico results show that the differential expression levels of TSGA10 and GGNBP2 were significant in the GEO datasets of BTs compared to normal samples (with adjusted p-value<0.05 and log fold change > 1). This study's experimental results showed that the TSGA10 gene produces four different transcripts with two distinct promoter regions and splicing exon 4. The relative mRNA expression of transcripts without exon 4 was higher than transcripts with exon 4 in BT samples (p-value<001). In GGNBP2, exon 2 in the 5'UTR region and exon 6 in the coding sequence were spliced. The expression analysis results showed that the relative mRNA expression of transcript variants without exon 2 was higher than other transcript variants with exon 2 in BT samples (p-value<001).

Conclusion

The decreased expression levels of transcripts with longer 5'UTR in BT samples than in testicular or low-grade brain tumor samples may decrease their translation efficiency. Therefore, decreased amounts of TSGA10 and GGNBP2 as potential tumor suppressor proteins, especially in high-grade brain tumors, may cause cancer development by angiogenesis and metastasis.

Loss-of-function mutation in TSGA10 causes acephalic spermatozoa phenotype in human

Background

Acephalic spermatozoa is an extremely rare type of teratozoospermia that is associated with male infertility. Several genes have been reported to be relevant to acephalic spermatozoa. Thus, more genetic pathogenesis needs to be explored.

Methods

Whole‐exome sequencing was performed in a patient with acephalic spermatozoa. Then Sanger sequencing was used for validation in the patient and his family. The patient's spermatozoa sample was observed by papanicolaou staining and transmission electron microscopy. Western blot and immunofluorescence were performed to detect the level and localization of related proteins.

Results

A novel homozygous frameshift insertion mutation c.545dupT;p.Ala183Serfs*10 in exon 8 of TSGA10 (NM_001349012.1) was identified. Our results showed misarranged mitochondrial sheath and abnormal flagellum in the patient's spermatozoa. TSGA10 failed to be detected in the patient's spermatozoa. However, the expression of SUN5 and PMFBP1 remained unaffected.

Conclusion

These results suggest that the novel homozygous frameshift insertion mutation of TSGA10 is a cause of acephalic spermatozoa.

TSGA10 overexpression inhibits angiogenesis of HUVECs: A HIF-2α biased perspective

Testis-specific gene antigen 10 (TSGA10) is a protein overexpressed in most cancers; except for some certain types where its expression is reduced. TSGA10 overexpression in HeLa cells has been shown to disrupt hypoxia inducible factor-1α (HIF-1α) axis and exert potent inhibitory effects. Since HIF-1α is structurally and biochemically similar to HIF-2α, TSGA10 is expected to bind HIF-2α and inhibit its function as well. This study elucidated that increased expression of TSGA10 in manipulated human umbilical vein endothelial cells (HUVECs) decreased the proliferation and migration of these cells as affirmed by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) and wound healing tests, respectively. It also inhibited in vitro angiogenesis of these cells in 3D collagen-cytodex model. Expression levels of genes controlled by HIF-2α including autocrine vascular endothelial growth factor (VEGF) were also assessed using real-time PCR. Our bioinformatic analysis also showed that TSGA10 could bind HIF-2α. Moreover, flow cytometry results indicated a cell cycle arrest in G2/M. Therefore, this study showed that overexpression of TSGA10, as a tumor suppressor gene, in endothelial cells resulted in decreased proliferation, migration and therefore, angiogenic activity of HUVECs. Since angiogenesis is vital for tumor development and metastasis, our findings could be of clinical significance in cancer therapy.