siRNA-mediated knockdown of sperm-associated antigen 11a (Spag11a) mRNA in epididymal primary epithelial cells affects proliferation: a transcriptome analyses

Effect of Spag11a gene knockout on the epididymis in mice: A histopathological and molecular analyses

The sperm-associated antigen 11a (Spag11a) gene is exclusively expressed in the caput epididymis. Our previous studies demonstrated that small interfering RNA (siRNA)-mediated ablation of this gene resulted in increased proliferation of epididymal epithelial cells. Further, active immunization-mediated ablation of SPAG11A protein increased the susceptibility of male reproductive tract tissues to diethylnitrosamine (DEN)-induced tumorigenesis. In this study, we report that the caput epididymis of Spag11a knockout mice displayed hyperplasia and inflammation, while the caput epididymis of wild-type mice exhibited normal anatomical structure. Global transcriptome analyses in the caput epididymis of knockout mice indicated differential expression of genes involved in a variety of cellular processes. The Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analyses suggested that the absence of Spag11a may activate microRNAs associated with cancer, chemical carcinogenesis-receptor activation, and chemical carcinogenesis-DNA adducts pathways; which may contribute to the promotion of tumorigenesis in the epididymis. The susceptibility of caput epididymis to chemically induced carcinogenesis in Spag11a knockout mice was analyzed. Histological analyses indicated that while the epididymis of wild-type mice did not show any signs of tumorigenesis, knockout mice displayed hyperplasia, anaplasia, dysplasia, neoplasia, and inflammation in the caput epididymis. Our results provide concrete evidence that deletion of Spag11a induces histopathological and molecular changes that contribute to tumorigenesis. It is possible that the expression of Spag11a gene could be one of the reasons for the rarity of epididymal cancers. The involvement of an epididymal gene in tumorigenesis is being demonstrated for the first time.

Ferroptosis as a Potential Cell Death Mechanism Against Cisplatin-Resistant Lung Cancer Cell Line

Purpose: Drug resistance is a challenging issue in cancer chemotherapy. Cell death induction is one of the main strategies to overcome chemotherapy resistance. Notably, ferroptosis has been considered a critical cell death mechanism in recent years. Accordingly, in this study, the different cell death strategies focused on ferroptosis have been utilized to overcome cisplatin resistance in an in vitro lung cancer model. Methods: The physiological functions of Akt1 and GPX4, as critical targets for ferroptosis and apoptosis induction, were suppressed by siRNA or antagonistic agents in resistant A549 cells. Afterward, the interventions' impacts on cell viability and reactive oxygen species (ROS) amount were analyzed by flow cytometry. Moreover, the alteration in the relevant gene and protein expression levels were quantified using Real-time PCR and western blot methods. Results: The result showed that the treatment with Akt1 siRNA reversed the cisplatin resistance in the A549 cell line through the induction of apoptosis. Likewise, the combination treatment of the GPX4 siRNA or FIN56 as ferroptosis inducers alongside cisplatin elevated ROS's cellular level, reduced the cellular antioxidant genes level and increased the cisplatin cytotoxic effect. Conclusion: In conclusion, our study indicated that ferroptosis induction can be considered a promising cell death strategy in cisplatin-resistant cancer cells.

Ablation of the sperm-associated antigen 11A (SPAG11A) protein by active immunization promotes epididymal oncogenesis in the rat

Incidence of cancer in the epididymis is very rare. It is proposed that proteins specific to this organ may contribute to this unique property. We previously demonstrated that siRNA-mediated knockdown of SPAG11A mRNA resulted in increased proliferation of epididymal epithelial cells, whereas overexpression of this gene caused reduced proliferation in immortalized cell lines. In this study, we evaluated the oncogenesis-related anatomical and transcriptome changes in the epididymis of SPAG11A-immunized rats challenged with a low dose of diethyl nitrosamine (DEN). DEN treatment or SPAG11A immunization alone did not cause any histopathological changes in the epididymis. Interestingly, indications of oncogenesis were observed in SPAG11A-immunized + DEN-treated rats. Using high throughput sequencing, we observed that 3549 transcripts that were differentially expressed in the caput epididymis of DEN only-treated rats displayed similar differential expression in the caput epididymis of SPAG11A-immunized rats, indicating that the microenvironment that contributes to oncogenesis sets in when SPAG11A protein is ablated. Differential expression of genes that are involved in 10 major cancer related pathways was also analyzed. Majority of the genes related to these pathways that were differentially expressed in the caput epididymis of DEN only-treated rats also showed similar pattern in the caput epididymis of SPAG11A-immunized rats. For the first time, results of our study demonstrate that ablation of SPAG11A by active immunization renders the epididymis susceptible to oncogenesis and that this protein may be one of the factors that contributes to the rarity of epididymal cancer.

Seasonal expressions of SPAG11A and androgen receptor in the epididymis of the wild ground squirrels (<em>Citellus dauricus</em> Brandt)

Sperm-associated antigen 11A (SPAG11A), a protein expressed exclusively in the epididymis, plays a vital and special role in regulating mammalian sperm maturation. The aim of this study was to investigate the seasonal expressions of SPAG11A and androgen receptor (AR) in the epididymis of the wild ground squirrels (Spermophilus dauricus Brandt). Morphologically, the results showed that epididymis length and weight in the breeding season were significantly higher than those of the non-breeding season. Histologically, the results revealed that enlarged lumen diameters, thickened epithelium and abundant sperm in the breeding season while reduced lumen diameters and epithelium with no sperm in the non-breeding season. SPAG11A was intensely expressed in cytoplasm and nucleus of epithelial cells and smooth muscle cells in the breeding season, and weaker staining in the non-breeding season. In the lumen of epididymis, SPAG11A immunostaining in the sperm of the epididymal corpus and cauda was higher than those in the caput during the breeding season. The immunostaining of AR was only presented in nucleus of smooth muscle cells and epithelial cells in the epididymis from the breeding season rather than the non-breeding season. The results of real-time quantitative PCR also showed that the mRNA levels of SPAG11A and AR in the epididymis during the breeding season were significantly higher than those of the non-breeding season. In addition, the circulating testosterone, follicle- stimulating hormone and luteinizing hormone levels in the squirrels were higher in the breeding season compared with those in the non-breeding season. Taken together, these results implied that SPAG11A might be involved in regulating seasonal changes in epididymal functions of the wild ground squirrels.