No abstract

Malignant cancers employ diverse and intricate immune evasion strategies, which lead to inadequately effective responses of many clinical cancer therapies. However, emerging data suggest that activation of the tolerant innate immune system in cancer patients is able, at least partially, to counteract tumor-induced immunosuppression, which indicates triggering of the innate immune response as a novel immunotherapeutic strategy may result in improved therapeutic outcomes for cancer patients. The promising innate immune targets include Toll-like Receptors (TLRs), RIG-I-like Receptors (RLRs), and Stimulator of Interferon Genes (STING). This review discusses the antitumor properties of TLRs, RLRs, and STING-mediated innate immune pathways, as well as the promising innate immune targets for potential application in cancer immunotherapy.

Purpose: Our study aimed to investigate whether CAF (cancer-associated fibroblasts) were involved in long noncoding RNAs (lncRNA)-regulated radioresponse in esophageal squamous cell carcinoma (ESCC). Experimental Design: By use of lncRNAs PCR array, 38 lncRNAs were screened in esophageal cancer cells and in normal esophageal epithelial cells Het-1A. LncRNA DNM3OS was detected in tumor tissues of patients with ESCC and in matched normal esophageal epithelial tissues by qRT-PCR analysis and in situ hybridization assay. The association of DNM3OS and tumor radioresistance was investigated in vitro and in vivo. The influences of DNM3OS on DNA damage response (DDR) was investigated by Western blotting, immunofluorescence imaging, and comet assay. The mechanisms by which CAFs promoted DNM3OS expression was investigated by kinase inhibitors' screening, luciferase assay, and chromatin immunoprecipitation. Results: Among the 38 lncRNAs tested, DNM3OS was found to have a much higher expression level in esophageal cancer cells than in Het-1A. In tumor tissues of 16 patients with ESCC, the expression level of DNM3OS showed an average increase of 6.3429-fold compared with that in matched normal tissues. DNM3OS conferred significant radioresistance in vitro and in vivo by regulating DDR. CAFs promoted the expression of DNM3OS with a 39.2554-fold and 38.3163-fold increase in KYSE-30 and KYSE-140, respectively. CAFs promoted the expression of DNM3OS in a PDGFb/PDGFRb/ FOXO1 signaling pathway-dependent manner. FOXO1, a transcription factor downstream of PDGFb/PDGFRb signaling pathway, initiated the transcription of DNM3OS by binding to DNM3OS promoter. Conclusions: Our study highlighted CAF-promoted DNM3OS as an attractive target to reverse tumor radioresistance in ESCC.

SUMMARYThe Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) is a highly contagious virus that underlies the current COVID-19 pandemic. SARS-CoV-2 is thought to disable various features of host immunity and cellular defense. The SARS-CoV-2 nonstructural protein 1 (Nsp1) is known to inhibit host protein translation and could be a target for antiviral therapy against COVID-19. However, how SARS-CoV-2 circumvents this translational blockage for the production of its own proteins is an open question. Here, we report a bipartite mechanism of SARS-CoV-2 Nsp1 which operates by: (1) hijacking the host ribosome via direct interaction of its C-terminal domain (CT) with the 40S ribosomal subunit and (2) specifically lifting this inhibition for SARS-CoV-2 via a direct interaction of its N-terminal domain (NT) with the 5’ untranslated region (5’ UTR) of SARS-CoV-2 mRNA. We show that while Nsp1-CT is sufficient for binding to 40S and inhibition of host protein translation, the 5’ UTR of SARS-CoV-2 mRNA removes this inhibition by binding to Nsp1-NT, suggesting that the Nsp1-NT-UTR interaction is incompatible with the Nsp1-CT-40S interaction. Indeed, lengthening the linker between Nsp1-NT and Nsp1-CT of Nsp1 progressively reduced the ability of SARS-CoV-2 5’ UTR to escape the translational inhibition, supporting that the incompatibility is likely steric in nature. The short SL1 region of the 5’ UTR is required for viral mRNA translation in the presence of Nsp1. Thus, our data provide a comprehensive view on how Nsp1 switches infected cells from host mRNA translation to SARS-CoV-2 mRNA translation, and that Nsp1 and 5’ UTR may be targeted for anti-COVID-19 therapeutics.