Innate Immune Stimulation in Cancer Therapy

Therapeutic Development by Targeting the cGAS-STING Pathway in Autoimmune Disease and Cancer

DNA immune recognition regulation mediated by the cGAS-STING pathway plays an important role in immune functions. Under normal physiological conditions, cGAS can recognize and bind to invading pathogen DNA and activate the innate immune response. On the other hand, abnormal activation of cGAS or STING is closely related to autoimmune diseases. In addition, activation of STING proteins as a bridge connecting innate immunity and adaptive immunity can effectively restrain tumor growth. Therefore, targeting the cGAS-STING pathway can alleviate autoimmune symptoms and be a potential drug target for treating cancer. This article summarizes the current progress on cGAS-STING pathway modulators and lays the foundation for further investigating therapeutic development in autoimmune diseases and tumors.

Development of a Novel Prognostic Signature Based on Antigen Processing and Presentation in Patients with Breast Cancer

Background: Complex antigen processing and presentation processes are involved in the development and progression of breast cancer (BC). A single biomarker is unlikely to adequately reflect the complex interplay between immune cells and cancer; however, there have been few attempts to find a robust antigen processing and presentation-related signature to predict the survival outcome of BC patients with respect to tumor immunology. Therefore, we aimed to develop an accurate gene signature based on immune-related genes for prognosis prediction of BC. Methods: Information on BC patients was obtained from The Cancer Genome Atlas. Gene set enrichment analysis was used to confirm the gene set related to antigen processing and presentation that contributed to BC. Cox proportional regression, multivariate Cox regression, and stratified analysis were used to identify the prognostic power of the gene signature. Differentially expressed mRNAs between high- and low-risk groups were determined by KEGG analysis. Results: A three-gene signature comprising HSPA5 (heat shock protein family A member 5), PSME2 (proteasome activator subunit 2), and HLA-F (major histocompatibility complex, class I, F) was significantly associated with OS. HSPA5 and PSME2 were protective (hazard ratio (HR) < 1), and HLA-F was risky (HR > 1). Risk score, estrogen receptor (ER), progesterone receptor (PR) and PD-L1 were independent prognostic indicators. KIT and ACACB may have important roles in the mechanism by which the gene signature regulates prognosis of BC. Conclusion: The proposed three-gene signature is a promising biomarker for estimating survival outcomes in BC patients.

Potential therapeutic applications of phytoconstituents as immunomodulators: Pre-clinical and clinical evidences

Autoimmune and infectious diseases are the major public health issues and have gained great attention in the last few years for the search of new agents with therapeutic benefits on the host immune functions. In recent years, natural products (NPs) have been studied broadly for their multi-targeted activities under pathological conditions. Interestingly, several attempts have been made to outline the immunomodulatory properties of NPs. Research on in-vitro and in-vivo models have shown the immunomodulatory activity of NPs, is due to their antiinflammatory property, induction of phagocytosis and immune cells stimulation activity. Moreover, studies on humans have suggested that phytomedicines reduce inflammation and could provide appropriate benefits either in single form or complex combinations with other agents preventing disease progression, subsequently enhancing the efficacy of treatment to combat multiple malignancies. However, the exact mechanism of immunomodulation is far from clear, warranting more detailed investigations on their effectiveness. Nevertheless, the reduction of inflammatory cascades is considered as a prime protective mechanism in a number of inflammation regulated autoimmune diseases. Altogether, this review will discuss the biological activities of plant-derived secondary metabolites, such as polyphenols, alkaloids, saponins, polysaccharides and so forth, against various diseases and their potential use as an immunomodulatory agent under pathological conditions.

BRD4 inhibition exerts anti-viral activity through DNA damage-dependent innate immune responses

Chromatin dynamics regulated by epigenetic modification is crucial in genome stability and gene expression. Various epigenetic mechanisms have been identified in the pathogenesis of human diseases. Here, we examined the effects of ten epigenetic agents on pseudorabies virus (PRV) infection by using GFP-reporter assays. Inhibitors of bromodomain protein 4 (BRD4), which receives much more attention in cancer than viral infection, was found to exhibit substantial anti-viral activity against PRV as well as a range of DNA and RNA viruses. We further demonstrated that BRD4 inhibition boosted a robust innate immune response. BRD4 inhibition also de-compacted chromatin structure and induced the DNA damage response, thereby triggering the activation of cGAS-mediated innate immunity and increasing host resistance to viral infection both in vitro and in vivo. Mechanistically, the inhibitory effect of BRD4 inhibition on viral infection was mainly attributed to the attenuation of viral attachment. Our findings reveal a unique mechanism through which BRD4 inhibition restrains viral infection and points to its potent therapeutic value for viral infectious diseases.

BRD4 has been well investigated in tumorigenesis for its contribution to chromatin remodeling and gene transcription. BRD4 inhibitors are used as promising chemotherapeutic drugs for cancer therapy. Here, we show a unique mechanism through which BRD4 inhibition broadly inhibits attachment of DNA and RNA viruses through DNA damage-dependent antiviral innate immune activation via the cGAS-STING pathway, in both cell culture and an animal model. STING-associated innate immune signaling has been considered to be a new possibility for cancer therapy, and STING agonists have been tested in early clinical trials. Our data identify BRD4 inhibitors as a potent therapy not only for viral infection but also for cancer immunotherapy.

Structural characterization of a novel Lactarius volemus Fr. polysaccharide and its immunity activity in BALB/c mice

Lactarius volemus Fr. has been regarded as a great edible medicinal fungal resource in China. In this study, L. volemus Fr. polysaccharide (LVP) with an average molecular weight of 16.842 kDa was obtained by water extraction. The structure of LVP was characterized to be mannan, and the linkages in the mannan were found to comprise the Manp, (1→4)-α-Man and (1→4,6)-α-Man. Furthermore, intraperitoneal administration of LVP increased the thymus, spleen and liver indices, dose-dependently. Additionally, LVP enhanced the immune response and the phagocytic activities. Pathological evaluations showed that LVP in mice increased the proliferation of red medullary lymphocytes (60–70%). Collectively, these results indicated that LVP might be a potential resource of raw material for further investigations of functional foods.

Lactarius volemus Fr. has been regarded as a great edible medicinal fungal resource in China.

Bioactive modulators targeting STING adaptor in cGAS-STING pathway

The cyclic GMP-AMP synthase (cGAS)-stimulator of interferon genes (STING)-pathway triggers innate immune responses by recognizing cytosolic DNA. Recent studies revealed that STING adaptor associates with various diseases, and several modulators targeting STING have been identified including three agonists that have entered clinical trials for treating cancer over the past 2 years. In particular, the efficacy of STING agonists and/or antagonists suggests adaptor STING as a potential therapeutic target for diverse diseases. Herein, we summarize the latest advances in understanding STING functioning and provide an overview of recent STING modulator discoveries, including structural details and the potential therapeutic applications of these modulators.

Limitations in the Design of Chimeric Antigen Receptors for Cancer Therapy

Cancer therapy has entered a new era, transitioning from unspecific chemotherapeutic agents to increasingly specific immune-based therapeutic strategies. Among these, chimeric antigen receptor (CAR) T cells have shown unparalleled therapeutic potential in treating refractory hematological malignancies. In contrast, solid tumors pose a much greater challenge to CAR T cell therapy, which has yet to be overcome. As this novel therapeutic modality matures, increasing effort is being invested to determine the optimal structure and properties of CARs to facilitate the transition from empirical testing to the rational design of CAR T cells. In this review, we highlight how individual CAR domains contribute to the success and failure of this promising treatment modality and provide an insight into the most notable advances in the field of CAR T cell engineering.