In the tumor microenvironment, the cytosolic DNA sensing, cyclic GMP-AMP synthase- stimulator of interferon genes (cGAS-STING) pathway is a crucial regulator of immune response. The cGAS of innate immunity recognizes cytoplasmic DNA by catalyzing cyclic GMP-AMP (cGAMP), which subsequently activates the STING pathway. STING activation leads to the phosphorylation of TANK-binding kinase 1 (TBK1) and recruitment of key transcription factor IRF3, notably to initiate the production of pro-inflammatory cytokines and Type I IFNs. This cascade enhances antigen presentation and primes cytotoxic T-cells, leading to the induction of anti-tumor immune response. Specific crosstalk mechanisms, such as TBK1-mediated negative feedback to limit excessive STING activation or its cooperation with NF-κB to balance immune responses, play pivotal roles in shaping tumor immunity. Harnessing this axis in cancer immunotherapy has emerged as a promising strategy, offering synergy with immune checkpoint blockade and CAR T-cells therapy. Fine-tuning activation of this pathway is crucial for balanced immune responses, making cGAS-STING/TBK1 signal transduction a major target for novel cancer therapies. This review elucidates the intricate crosstalk mechanisms of cGAS-STING and TBK1 signal transduction within tumor microenvironment. These may shed insight on cancer therapy options and their pivotal roles in modulating tumor immunity.
Background: Non-Hodgkin-Lymphoma (NHL), the most prevalent hematologic malignancies in the world has majorly originates from B cells. R-CHOP represents the new-standard treatment regimen for NHL. Most NHL patients initially respond to chemotherapy yielding complete response rates of 40–50%. Unfortunately, a substantial population of patients undergo relapse, resulting in poor clinical ramifications. The onset of NHL relapse evolves from several months (early relapse) to years (late relapse) after the initial remission. However, the majority of relapse occurs within two years of initial treatment. Despite considerable advancements in therapeutic concepts and techniques, disease relapse with limited response rate remains a major challenge and depicts poor prognosis in successful clinical management. Patient’s response to chemotherapy varies widely from static disease to cancer recurrence and the later is primarily associated with generation of multi drug resistance (MDR) phenotypes that ultimately promotes disease progression and metastasis. However, the causes of differential responses to standard chemotherapeutic regimens and therapy failure in NHL patients are yet to be elucidated. Aims: To understand the influence of immune cells in differential response in NHL patients following R-CHOP-therapy. Methods: Peripheral blood was collected from 51 CD20+ NHL patients before and after frontline chemotherapy and at the time of relapse. Clinical variables at diagnosis (age, performance status, stage of the disease, number of extra nodal lesions) were obtained to calculate prognostic indices (IPI). A panel of immune cells CD4+ T cells, CD8+ T cells, Cytotoxic T cells, CD8+CD45RO+CD45RA+ Memory T cells, CD14+CD80+ M1 macrophage, CD4+CD25+FoxP3 regulatory T cells(Treg), CD33+CD11b+CD14-/+CD15-/+ Myeloid Derived Supressor Cells(MDSCs), CD14+CD163+ Tumor associated Macrophages (TAM), MDR phenotype P-gp(ABCB1) and MRP1(ABCC1) were studied by flow-cytometry at different phases of treatment. In vivo and in vitro doxorubicin resistance model were developed with murine Dalton’s lymphoma and Raji (B cell), Jurkat cell (T cell) lines respectively and impact of responsible immune cells on generation of drug resistance were studied by RT-PCR, qPCR, flow-cytometry, colorimetric assay, gene silencing and ChIP assays. Results: A strong positive correlation between elevated levels of CD33+CD11b+CD14+CD15-monocytic MDSCs, but not CD33+CD11b+CD14-CD15+ granulocytic MDSC and MDR was depicted in non-responder patients compared to responder cohorts. Moreover, in vitro supplementation of MDSCs in murine or human lymphoma culture increases the expression of mrp1, pgp and cellular GSH level from early passage than passage without MDSCs, which is correlated well with in vitro drug retention and generation of drug resistance phenotypes and tumor progression. MDSC secreted cytokines IL-6, IL-10, IL-1β are the dominant constituent in regulating expression of multidrug-resistance pump by modulating STAT3, STAT1 and NF-κβ signalling axis. Summary/Conclusion: Observed correlation between monocytic MDSCs with the relapse of NHL patients following R-CHOP-therapy along in vitro data from lymphoma cells suggest monocytic MDSCs might be considered as a new potential biomarker and therapeutic target to enhance the relapse free survival in NHL patients.
Abstract Background A dynamic interaction between tumor cells and its surrounding stroma promotes the initiation, progression, metastasis, and chemoresistance of solid tumors. Emerging evidences suggest that targeting the stromal events could improve the efficacies of current therapeutics. Within tumor microenvironment (TME), stromal progenitor cells, i.e., MSCs, interact and eventually modulate the biology and functions of cancer and immune cells. Our recent finding disclosed a novel mechanism stating that tumor-associated MSCs inhibit the T cell proliferation and effector functions by blocking cysteine transport to T cells by dendritic cells (DCs), which makes MSCs as a compelling candidate as a therapeutic target. Immunomodulation by nontoxic neem leaf glycoprotein (NLGP) on dysfunctional cancer immunity offers significant therapeutic benefits to murine tumor host; however, its modulation on MSCs and its impact on T cell functions need to be elucidated. Methods Bone marrow-derived primary MSCs or murine 10 T1/2 MSCs were tumor-conditioned (TC-MSCs) and co-cultured with B16 melanoma antigen-specific DCs and MACS purified CD4 + and CD8 + T cells. T cell proliferation of T cells was checked by Ki67-based flow-cytometric and thymidine-incorporation assays. Cytokine secretion was measured by ELISA. The expression of cystathionase in DCs was assessed by RT-PCR. The STAT3/pSTAT3 levels in DCs were assessed by western blot, and STAT3 function was confirmed using specific SiRNA. Solid B16 melanoma tumor growth was monitored following adoptive transfer of conditioned CD8 + T cells. Results NLGP possesses an ability to restore anti-tumor T cell functions by modulating TC-MSCs. Supplementation of NLGP in DC-T cell co-culture significantly restored the inhibition in T cell proliferation and IFNγ secretion almost towards normal in the presence of TC-MSCs. Adoptive transfer of NLGP-treated TC-MSC supernatant educated CD8 + T cells in solid B16 melanoma bearing mice resulted in better tumor growth restriction than TC-MSC conditioned CD8 + T cells. NLGP downregulates IL-10 secretion by TC-MSCs, and concomitantly, pSTAT3 expression was downregulated in DCs in the presence of NLGP-treated TC-MSC supernatant. As pSTAT3 negatively regulates cystathionase expression in DCs, NLGP indirectly helps to maintain an almost normal level of cystathionase gene expression in DCs making them able to export sufficient amount of cysteine required for optimum T cell proliferation and effector functions within TME. Conclusions NLGP could be a prospective immunotherapeutic agent to control the functions and behavior of highly immunosuppressive TC-MSCs providing optimum CD8 + T cell functions to showcase an important new approach that might be effective in overall cancer treatment.
Introduction Murine tumor growth restriction by neem leaf glycoprotein (NLGP) was established in various transplanted models of murine sarcoma, melanoma and carcinoma. However, the role of NLGP in the sequential carcinogenic steps has not been explored. Thus, tongue carcinogenesis in Swiss mice was induced by 4-nitroquinoline-1-oxide (4NQO), which has close resemblance to human carcinogenesis process. Interventional role of NLGP in initiation-promotion protocol established during 4NQO mediated tongue carcinogenesis in relation to systemic immune alteration and epithelial-mesenchymal transition (EMT) is investigated. Methods 4NQO was painted on tongue of Swiss mice every third day at a dose of 25µl of 5mg/ml stock solution. After three consecutive treatments with 4NQO (starting Day7), one group of mice was treated with NLGP (s.c. 25μg/mice/week), keeping a group as PBS control. Mice were sacrificed in different time-intervals to harvest tongues and studied using histology, immunohistochemistry, flow-cytometry and RT-PCR on different immune cells and EMT markers (e-cadherin, vimentin) to elucidate their phenotypic and secretory status. Results Local administration of 4NQO for consecutive 300 days promotes significant alteration in tongue mucosa including erosion in papillae and migration of malignant epithelial cells to the underlying connective tissue stroma with the formation of cell nests (exophytic-hyperkeratosis with mild dysplasia). Therapeutic NLGP treatment delayed pre-neoplastic changes promoting normalization of mucosa by maintaining normal structure. Flow-cytometric evidences suggest that NLGP treatment upregulated CD8 + , IFNγ + , granzyme B + , CD11c + cells in comparison to 4NQO treated mice with a decrease in Ki67 + and CD4 + FoxP3 + cells in NLGP treated cohort. RT-PCR demonstrated a marked reduction of MMP9, IL-6, IL-2, CD31 and an upregulation in CCR5 in tongues from 4NQO+NLGP treated mice in comparison to 4NQO treated group. Moreover, 4NQO mediated changes were associated with reduction of e-cadherin and simultaneous up-regulation of vimentin expression in epithelium that was partially reversed by NLGP. Discussion Efficacy of NLGP was tested first time in sequential carcinogenesis model and proved effective in delaying the initial progression. NLGP normalizes type 1 immunity including activation of the CD8 + T effector functions, reduction of regulatory T cell functions, along with changes in EMT to make the host systemically alert to combat the carcinogenic threat.
<div>Abstract<p>Targeting exhausted CD8<sup>+</sup> T-cell (T<sub>EX</sub>)–induced aggravated cancer stem cells (CSC) holds immense therapeutic potential. In this regard, immunomodulation via Neem Leaf Glycoprotein (NLGP), a plant-derived glycoprotein immunomodulator is explored. Since former reports have proven immune dependent–tumor restriction of NLGP across multiple tumor models, we hypothesized that NLGP might reprogram and rectify T<sub>EX</sub> to target CSCs successfully. In this study, we report that NLGP’s therapeutic administration significantly reduced T<sub>EX</sub>-associated CSC virulence in <i>in vivo</i> B16-F10 melanoma tumor model. A similar trend was observed in <i>in vitro</i> generated T<sub>EX</sub> and B16-F10/MCF7 coculture setups. NLGP rewired CSCs by downregulating clonogenicity, multidrug resistance phenotypes and PDL1, OCT4, and SOX2 expression. Cell cycle analysis revealed that NLGP educated–T<sub>EX</sub> efficiently pushed CSCs out of quiescent phase (G<sub>0</sub>G<sub>1</sub>) into synthesis phase (S), supported by hyper-phosphorylation of G<sub>0</sub>G<sub>1</sub>–S transitory cyclins and Rb proteins. This rendered quiescent CSCs susceptible to S-phase–targeting chemotherapeutic drugs like 5-fluorouracil (5FU). Consequently, combinatorial treatment of NLGP and 5FU brought optimal CSC-targeting efficiency with an increase in apoptotic bodies and proapoptotic BID expression. Notably a strong nephron-protective effect of NLGP was also observed, which prevented 5FU-associated toxicity. Furthermore, Dectin-1–mediated NLGP uptake and subsequent alteration of Notch1 and mTOR axis were deciphered as the involved signaling network. This observation unveiled Dectin-1 as a potent immunotherapeutic drug target to counter T-cell exhaustion. Cumulatively, NLGP immunotherapy alleviated exhausted CD8<sup>+</sup> T-cell-induced CSC aggravation.</p><p><b>Implications:</b> Our study recommends that NLGP immunotherapy can be utilized to counter ramifications of T-cell exhaustion and to target therapy elusive aggressive CSCs without evoking toxicity.</p></div>
'%3e%3ccircle r='20' fill='%23008'/%3e%3ccircle r='17.5' fill='%23fff'/%3e%3ccircle r='3.5' fill='%23008'/%3e%3cg id='d'%3e%3cg id='c'%3e%3cg id='b'%3e%3cg id='a' fill='%23008'%3e%3ccircle r='.875' transform='rotate(7.5 -8.75 133.5)'/%3e%3cpath d='M0 17.5.6 7 0 2l-.6 5L0 17.5z'/%3e%3c/g%3e%3cuse xlink:href='%23a' transform='rotate(15)'/%3e%3c/g%3e%3cuse xlink:href='%23b' transform='rotate(30)'/%3e%3c/g%3e%3cuse xlink:href='%23c' transform='rotate(60)'/%3e%3c/g%3e%3cuse xlink:href='%23d' transform='rotate(120)'/%3e%3cuse xlink:href='%23d' transform='rotate(-120)'/%3e%3c/g%3e%3c/svg%3e)
