MicroRNA-326 negatively regulates CD155 expression in lung adenocarcinoma.

Treatment with immune checkpoint inhibitors induces a durable response in some patients with non-small-cell lung cancer, but eventually gives rise to drug resistance. Upregulation of CD155 expression is implicated as one mechanism of resistance to programmed death receptor-1 (PD-1)/PD-1 ligand (PD-L1) inhibitors, and it is therefore important to characterize the mechanisms underlying regulation of CD155 expression in tumor cells. The aim of this study was to identify microRNAs (miRNAs) that might regulate CD155 expression at the posttranscriptional level in lung cancer. Comprehensive miRNA screening with target prediction programs and a dual-luciferase reporter assay identified miR-346, miR-328-3p, miR-326, and miR-330-5p as miRNAs that bind to the 3'-UTR of CD155 mRNA. Forced expression of these miRNAs suppressed CD155 expression in lung cancer cell lines. Immunohistochemical staining of CD155 in tissue specimens from 57 patients with lung adenocarcinoma revealed the median tumor proportion score for CD155 to be 68%. The abundance of miR-326 in these specimens with a low level of CD155 expression was significantly greater than in specimens with a high level (p < 0.005). Our results thus suggest that miR-326 negatively regulates CD155 expression in lung adenocarcinoma and might therefore play a role in the development of resistance to PD-1/PD-L1 inhibitors.

Binding mode of the side-by-side two-IgV molecule CD226/DNAM-1 to its ligand CD155/Necl-5.

Natural killer (NK) cells are important component of innate immunity and also contribute to activating and reshaping the adaptive immune responses. The functions of NK cells are modulated by multiple inhibitory and stimulatory receptors. Among these receptors, the activating receptor CD226 (DNAM-1) mediates NK cell activation via binding to its nectin-like (Necl) family ligand, CD155 (Necl-5). Here, we present a unique side-by-side arrangement pattern of two tandem immunoglobulin V-set (IgV) domains deriving from the ectodomains of both human CD226 (hCD226-ecto) and mouse CD226 (mCD226-ecto), which is substantially different from the conventional head-to-tail arrangement of other multiple Ig-like domain molecules. The hybrid complex structure of mCD226-ecto binding to the first domain of human CD155 (hCD155-D1) reveals a conserved binding interface with the first domain of CD226 (D1), whereas the second domain of CD226 (D2) both provides structural supports for the unique architecture of CD226 and forms direct interactions with CD155. In the absence of the D2 domain, CD226-D1 exhibited substantially reduced binding efficacy to CD155. Collectively, these findings would broaden our knowledge of the interaction between NK cell receptors and the nectin/Necl family ligands, as well as provide molecular basis for the development of CD226-targeted antitumor immunotherapeutics.

Conservation of structural and interactional features of CD226 and Necl5 molecules from Nile tilapia (Oreochromis niloticus).

CD226 interacts with its ligand Necl5 as a costimulatory signal. In this study, we cloned a CD226 from Nile tilapia (Oreochromis niloticus, named OnCD226) and a Necl5 (named OnNecl5). The open reading frame of OnCD226 was 1071 bp, encoding a protein of 356 amino acids. Sequence alignment analysis indicated that OnCD226 contained two Ig-like domains in ectodomain. The open reading frame of OnNecl5 was 1155 bp, encoding a protein of 384 amino acids, and there are three lg-like domains in the extracellular domain. In healthy tilapia, OnCD226 was distributed in all tested tissues and relatively higher in the brain, while OnNecl5 was relatively higher in the skin. After Streptococcus agalactiae infection, OnCD226 has the same up-regulated expression pattern as OnNecl5 in different tissues. After HKLs stimulation with S. agalactiae and Poly I:C, respectively. OnCD226 was significantly up-regulated (0.01 < p < 0.05) at 12 h and extremely significant up-regulation was observed (p < 0.01) at 48 h and 96 h, the peak was observed at 96 h after stimulation by S. agalactiae. After stimulation by Poly I:C, OnCD226 expression was extremely significant (p < 0.01) at 72 h and 96 h, the peak was observed at 96 h. After stimulation by Keyhole limpet hemocyanin (KLH), a classical T cell-dependent antigen, the expression of OnCD226 was significantly up-regulated in blood, head kidney, spleen, and thymus. Moreover, when compared with the first challenge, the gene expression of OnCD226 which response to the second challenge was up-regulated earlier. Subcellular co-localization studies showed that OnCD226 and OnNecl5 were distributed mainly in the cytomembrane. Yeast two-hybrid results, indicated a strong interaction between OnCD226 and OnNecl5. These results suggested that OnCD226 plays an important role during pathogens infection, and the interaction between CD226 and Necl5 is conserved in Nile tilapia.

Structural basis for the recognition of nectin-like protein-5 by the human-activating immune receptor, DNAM-1.

Nectin and nectin-like (Necl) adhesion molecules are broadly overexpressed in a wide range of cancers. By binding to these adhesion molecules, the immunoreceptors DNAX accessory molecule-1 (DNAM-1), CD96 molecule (CD96), and T-cell immunoreceptor with Ig and ITIM domains (TIGIT) play a crucial role in regulating the anticancer activities of immune effector cells. However, within this axis, it remains unclear how DNAM-1 recognizes its cognate ligands. Here, we determined the structure of human DNAM-1 in complex with nectin-like protein-5 (Necl-5) at 2.8 Å resolution. Unexpectedly, we found that the two extracellular domains (D1-D2) of DNAM-1 adopt an unconventional "collapsed" arrangement that is markedly distinct from those in other immunoglobulin-based immunoreceptors. The DNAM-1/Necl-5 interaction was underpinned by conserved lock-and-key motifs located within their respective D1 domains, but also included a distinct interface derived from DNAM-1 D2. Mutation of the signature DNAM-1 "key" motif within the D1 domain attenuated Necl-5 binding and natural killer cell-mediated cytotoxicity. Altogether, our results have implications for understanding the binding mode of an immune receptor family that is emerging as a viable candidate for cancer immunotherapy.

Roles of the third Ig-like domain of Necl-5/PVR and the fifth Ig-like domain of the PDGF receptor in its signaling.

The immunoglobulin (Ig)-like cell adhesion molecule nectin-like molecule (Necl)-5/poliovirus receptor is up-regulated in many types of cancer cells and implicated in their abnormally enhanced cell proliferation and movement. We previously showed that Necl-5 cis-interacts with the platelet-derived growth factor (PDGF) receptor ß through the extracellular region and enhances its signaling. Although this cis-interaction does not affect the PDGF-induced tyrosine phosphorylation of the receptor, the interaction of the cytoplasmic region of Necl-5 with sprouty2 and the regulation of its activity are required for the enhancement of the PDGF receptor ß signaling by Necl-5. We investigated here the more detailed mechanism for this cis-interaction of Necl-5 with the PDGF receptor ß. Necl-5 contains three Ig-like domains and the PDGF receptor ß contains five Ig-like domains at their extracellular regions. We showed here that the third Ig-like domain of Necl-5 cis-interacted with the fifth Ig-like domain of the PDGF receptor ß. The recombinant protein of the third Ig-like domain of Necl-5 inhibited the cis-interaction of full-length Necl-5 with the PDGF receptor ß and the PDGF-induced activation of the ERK signaling pathway that was enhanced by Necl-5. These results revealed the novel roles of the third Ig-like domain of Necl-5 and the fifth Ig-like domain of the PDGF receptor ß in its signaling.

Emerging Recombinant Oncolytic Poliovirus Therapies Against Malignant Glioma: A Review.

Glioblastoma multiforme (GBM) is a fourth-grade malignant glioma that continues to be the main contributor to primary malignant brain tumour-related death in humans. The most prevalent primary brain tumours are gliomas. The most dangerous of these neoplasms, GBM, has been shown to be one of the most lethal and refractory tumours. For those who have been diagnosed with GBM, the median time to progression, as determined by magnetic resonance imaging, is roughly six months, and the median survival is approximately one year. GBM is challenging to manage with old treatments like chemotherapy, tumour debulking, and radiation therapy. Treatment outcomes are poor, and due to this effect, the treatment is not up to the mark. GBM also shows diagnostic complexity due to limitations in the use of specific targeted therapies. The treatment protocol followed currently has an entire focus on safe resection and radiotherapy. Protein synthesis is not tightly regulated physiologically in malignant cells, which promotes unchecked growth and proliferation. An innovative, experimental technique for treating cancer uses polioviruses that have been genetically altered to target a fascinating aberration of translation regulation in cancer. This approach enables precise and effective cancer cell targeting based on the convergence of numerous variables. Oncolytic viruses have revolutionised cancer treatment. However, their effectiveness in glioblastoma remains restricted, necessitating more improvement. Oncolytic poliovirus has shown great potential in the treatment of GBM. Factors like the blood-brain barrier, immunosuppressive tumour microenvironment (TME), and tumour heterogeneity make treatment for malignant gliomas ineffective. In this review, we have focused on oncolytic viruses, specifically oncolytic poliovirus, and we explore malignant glioma treatments. We have also discussed currently available conventional treatment options for malignant glioma and other brain tumours.

Prognostic significance of CD155 mRNA expression in soft tissue sarcomas.

CD155 was initially identified as a receptor for poliovirus. Several studies have demonstrated that CD155 overexpression in cancer cells is significant in their migration, invasion, proliferation and metastasis. The objective of the present study was to investigate the correlation between CD155 expression and the clinical aggressiveness of soft tissue tumors. The CD155 expression levels in 43 surgically-resected soft tissue tumors were evaluated using the quantitative real-time polymerase chain reaction (PCR). The clinicopathogical factors affecting the expression levels of CD155 mRNA were investigated and the association between the expression levels of CD155 and patient prognosis was identified. The CD155 expression level was not correlated with the patient gender, site of the primary tumor, tumor depth, tumor size or presence of distant metastasis at presentation, but was correlated with patient age (Fisher's exact test). The local recurrence-free survival rate for patients with a high CD155 expression level was observed to be significantly poorer compared with that of patients with low CD155 expression levels (P=0.0401). Moreover, a multivariate analysis indicated that a high CD155 expression level was an independent adverse prognostic factor for local recurrence-free survival (hazard ratio, 6.369; P=0.0328). The present study therefore suggests that the expression level of CD155 is a useful marker for predicting the local recurrence of soft tissue tumors.