Circular RNA (circRNA) is a novel subclass of noncoding-RNA molecules that participate in development and progression of a variety of human diseases via sponging microRNAs (miRNAs). Until now, the contributions of circRNAs in chemoresistance of hepatocellular carcinoma (HCC) remain largely unknown.In the present study, we aimed to investigate the role of circRNA in cisplatin resistance of HCC. We investigated the expression of circRNAs in 5 paired cisplatin-sensitive and cisplatin-resistant HCC tissues by microarray analysis. The qRT-PCR analysis was to investigate the expression pattern of circARNT2 in HCC patient tissues and cell lines. Then, the effects of circARNT2 on cisplatin resistance, cell proliferation, and apoptosis were assessed in HCC in vitro and in vivo. cir-cARNT2 was significantly upregulated in HCC tissues and cell lines. Overexpression of circARNT2 in HCC was significantly correlated with aggressive characteristics and served as an independent risk factor for overall survival in patients with HCC. In vitro experiments showed that knockdown of cir-cARNT2 inhibited cell proliferation and enhances the cisplatin sensitivity of HCC cells. Furthermore, circARNT2 facilitates HCC progression in vivo. We demonstrated that circARNT2 acts as a sponge for miR-155-5p and verified that PDK1 is a novel target of miR-155-5p. In summary, our study demonstrated that circARNT2 modulates cisplatin resistance through miR-155-5p/PDK1 pathway. Our findings indicated that cir-cARNT2 may serve as a promising therapeutic target for overcoming cisplatin resistance for HCC.

Apoptosis induced by endoplasmic reticulum (ER) stress plays a crucial role in mediating brain damage after ischemic stroke. Recently, Hes1 (hairy and enhancer of split 1) has been implicated in the regulation of ER stress, but whether it plays a functional role after ischemic stroke and the underlying mechanism remain unclear. In this study, using a mouse model of ischemic stroke via transient middle cerebral artery occlusion (tMCAO), we found that Hes1 was induced following brain injury, and that siRNA-mediated knockdown of Hes1 increased the cerebral infarction and worsened the neurological outcome, suggesting that Hes1 knockdown exacerbates ischemic stroke. In addition, mechanistically, Hes1 knockdown promoted apoptosis and activated the PERK/eIF2a/ATF4/ CHOP signaling pathway after tMCAO. These results suggest that Hes1 knockdown promotes ER stress-induced apoptosis. Furthermore, inhibition of PERK with the specific inhibitor GSK2606414 markedly attenuated the Hes1 knockdown-induced apoptosis and the increased cerebral infarction as well as the worsened neurological outcome following tMCAO, implying that the protection of Hes1 against ischemic stroke is associated with the amelioration of ER stress via modulating the PERK/ eIF2a/ATF4/CHOP signaling pathway. Taken together, these results unveil the detrimental role of Hes1 knockdown after ischemic stroke and further relate it to the regulation of ER stress-induced apoptosis, thus highlighting the importance of targeting ER stress in the treatment of ischemic stroke.

BackgroundCD8+ T cells, which play a vital role in response to adaptive immunity, are closely related to the immunization responses to kill tumor cells. Understanding the effects exerted by tumor-infiltrated CD8+ T cells in HPV+ and HPV- head and neck squamous cell carcinoma (HNSCC) patients is critical for predicting their prognosis as well as their responses towards immunization-related therapy.Materials and MethodsHNSCC single cell transcriptome was used to screen for differentially expressed genes (DEGs) based on CD8+ T cells. A gene signature associated with CD8+ T cells was built and verified with the cancer genome atlas dataset with a view to predicting the prognosis of HNSCC patients. Risk scores were calculated for HNSCC cases and categorized into either high- or low-risk cohorts. The prognosis-correlated data of the risk scores were analyzed by using Kaplan-Meier survival curves and multi-variate Cox regression plots. In addition, the possibility of using the genetic profiles to predict responses toward immunization-related therapy was explored.ResultsFrom the DEGs screened from the sequencing of single-cell RNA, a gene signature of 4 genes (ACAP1, ANKRD28, C12orf75, and M6PR) were identified. It was seen that these genes could predict overall survival in HPV+ HNSCC patients. In addition, high- and low-risk HPV+ HNSCC patients showed marked differences in their CD8+ T-cell infiltration due to immunization when clinical characteristics were taken into consideration. This correlated with their immunization therapy responses.ConclusionsOur work provides insights into explaining the restricted responses of current immunization checkpoint inhibiting substances in HPV+ HNSCC patients. A novel genetic signature to predict the prognosis and immunization-correlated therapeutic responses is presented. This will provide potential new therapeutic opportunities for HPV+ HNSCC patients.

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