Abrogation of Hn RNP L enhances anti-PD-1 therapy efficacy via diminishing PD-L1 and promoting CD8^(+) T cell-mediated ferroptosis in castration-resistant prostate cancer

Owing to incurable castration-resistant prostate cancer(CRPC)ultimately developing after treating with androgen deprivation therapy(ADT),it is vital to devise new therapeutic strategies to treat CRPC.Treatments that target programmed cell death protein 1(PD-1)and programmed death ligand-1(PD-L1)have been approved for human cancers with clinical benefit.However,many patients,especially prostate cancer,fail to respond to anti-PD-1/PD-L1 treatment,so it is an urgent need to seek a support strategy for improving the traditional PD-1/PD-L1 targeting immunotherapy.In the present study,analyzing the data from our prostate cancer tissue microarray,we found that PD-L1 expression was positively correlated with the expression of heterogeneous nuclear ribonucleoprotein L(Hn RNP L).Hence,we further investigated the potential role of Hn RNP L on the PD-L1 expression,the sensitivity of cancer cells to T-cell killing and the synergistic effect with anti-PD-1 therapy in CRPC.Indeed,Hn RNP L knockdown effectively decreased PD-L1 expression and recovered the sensitivity of cancer cells to T-cell killing in vitro and in vivo,on the contrary,Hn RNP L overexpression led to the opposite effect in CRPC cells.In addition,consistent with the previous study,we revealed that ferroptosis played a critical role in T-cell-induced cancer cell death,and Hn RNP L promoted the cancer immune escape partly through targeting YY1/PD-L1 axis and inhibiting ferroptosis in CRPC cells.Furthermore,Hn RNP L knockdown enhanced antitumor immunity by recruiting infiltrating CD8^(+)T cells and synergized with anti-PD-1 therapy in CRPC tumors.This study provided biological evidence that Hn RNP L knockdown might be a novel therapeutic agent in PD-L1/PD-1 blockade strategy that enhanced anti-tumor immune response in CRPC.

Apoptotic and nonapoptotic function of caspase 7 in spermatogenesis

Recent studies have reported that caspase 7 has an apoptotic and nonapoptotic function. However, the relationship between caspase 7 and spermatogenesis remains unknown. This study aimed to investigate the possible function of caspase 7 during normal and abnormal spermatogenesis. The cleaved form of caspase 7 was detected in testis tissues at different postpartum times （5-14 weeks） by qRT-PCR, Western blot and immunohistochemistry （IHC）. Then, the mice models of spermatogenic dysfunction were obtained by busulfan （30 mg kg-1） to further evaluate the potential function and mechanism of caspase 7. qRT-PCR and Western blot results showed that caspase 7 expression was gradually elevated from 5 to 14 weeks, which was not connected with apoptosis. IHC results revealed that caspase 7 was mainly located in spermatogenic cells and Leydig cells. In addition, spermatogenic dysfunction induced by busulfan gradually enhanced the apoptosis and elevated the expression of caspase 3, caspase 6, and caspase 9, but decreased the expression of caspase 7 in spermatogenic cells. However, when spermatogenic cells were mostly disappeared at the fourth week after busulfan treatment, caspase 7 expression in Leydig cells was significantly increased and positively correlated with the expression of caspase 3, caspase 6, and caspase 9. Therefore, these results indicate that caspase 7 has a nonapoptic function that participates in normal spermatogenesis, but also displays apoptotic function in spermatogenic dysfunction.