The Role of Myeloid-Derived Suppressor Cells (MDSC) in Cancer Progression. Vaccines (Basel). 2016;4:36. [PMID: 27827871 PMCID: PMC5192356 DOI: 10.3390/vaccines4040036]

Targeting myeloid-derived suppressor cells promotes antiparasitic T-cell immunity and enhances the efficacy of PD-1 blockade (15 words)

Immune exhaustion corresponds to a loss of effector function of T cells that associates with cancer or chronic infection. Here, our objective was to decipher the mechanisms involved in the immune suppression of myeloid-derived suppressor cells (MDSCs) and to explore the potential to target these cells for immunotherapy to enhance checkpoint blockade efficacy in a chronic parasite infection. We demonstrated that programmed cell-death-1 (PD-1) expression was significantly upregulated and associated with T-cell dysfunction in advanced alveolar echinococcosis (AE) patients and in Echinococcus multilocularis-infected mice. PD-1 blockade ex vivo failed to reverse AE patients' peripheral blood T-cell dysfunction. PD-1/PD-L1 blockade or PD-1 deficiency had no significant effects on metacestode in mouse model. This was due to the inhibitory capacities of immunosuppressive granulocytic MDSCs (G-MDSCs), especially in the liver surrounding the parasite pseudotumor. MDSCs suppressed T-cell function in vitro in an indoleamine 2, 3 dioxygenase 1 (IDO1)-dependent manner. Although depleting MDSCs alone restored T-cell effector functions and led to some limitation of disease progression in E. multilocularis-infected mice, combination with PD-1 blockade was better to induce antiparasitic efficacy. Our findings provide preclinical evidence in support of targeting MDSC or combining such an approach with checkpoint blockade in patients with advanced AE. (200 words).

Dual roles of myeloid-derived suppressor cells in various diseases: a review

Myeloid-derived suppressor cells (MDSCs) are a heterogeneous population of cells that originate from bone marrow stem cells. In pathological conditions, such as autoimmune disorders, allergies, infections, and cancer, normal myelopoiesis is altered to facilitate the formation of MDSCs. MDSCs were first shown to promote cancer initiation and progression by immunosuppression with the assistance of various chemokines and cytokines. Recently, various studies have demonstrated that MDSCs play two distinct roles depending on the physiological and pathological conditions. MDSCs have protective roles in autoimmune disorders (such as uveoretinitis, multiple sclerosis, rheumatoid arthritis, ankylosing spondylitis, type 1 diabetes, autoimmune hepatitis, inflammatory bowel disease, alopecia areata, and systemic lupus erythematosus), allergies, and organ transplantation. However, they play negative roles in infections and various cancers. Several immunosuppressive functions and mechanisms of MDSCs have been determined in different disease conditions. This review comprehensively discusses the associations between MDSCs and various pathological conditions and briefly describes therapeutic approaches.

Immune landscape of hepatocellular carcinoma: From dysregulation of the immune responses to the potential immunotherapies

Hepatocellular carcinoma (HCC) presents a considerable global health burden due to its late diagnosis and high morbidity. The liver's specific anatomical and physiological features expose it to various antigens, requiring precise immune regulation. To the best of our knowledge, this is the first time that a comprehensive overview of the interactions between the immune system and gut microbiota in the development of HCC, as well as the relevant therapeutic approaches are discussed. Dysregulation of immune compartments within the liver microenvironment drives HCC pathogenesis, characterized by elevated regulatory cells such as regulatory T cells (Tregs), myeloid-derived suppressor cells, and M2 macrophages as well as suppressive molecules, alongside reduced number of effector cells like T cells, natural killer cells, and M1 macrophages. Dysbiosis of gut microbiota also contributes to HCC by disrupting intestinal barrier integrity and triggering overactivated immune responses. Immunotherapy approaches, particularly immune checkpoint inhibitors, have exhibited promise in HCC management, yet adoptive cell therapy and cancer vaccination research are in the early steps with relatively less favorable outcomes. Further understanding of immune dysregulation, gut microbiota involvement, and therapeutic combination strategies are essential for advancing precision immunotherapy in HCC.

The role and mechanism of cinnamaldehyde in cancer

As cancer continues to rise globally, there is growing interest in discovering novel methods for prevention and treatment. Due to the limitations of traditional cancer therapies, there has been a growing emphasis on investigating herbal remedies and exploring their potential synergistic effects when combined with chemotherapy drugs. Cinnamaldehyde, derived from cinnamon, has gained significant attention for its potential role in cancer prevention and treatment. Extensive research has demonstrated that cinnamaldehyde exhibits promising anticancer properties by modulating various cellular processes involved in tumor growth and progression. However, challenges and unanswered questions remain regarding the precise mechanisms for its effective use as an anticancer agent. This article aims to explore the multifaceted effects of cinnamaldehyde on cancer cells and shed light on these existing issues. Cinnamaldehyde has diverse anti-cancer mechanisms, including inducing apoptosis by activating caspases and damaging mitochondrial function, inhibiting tumor angiogenesis, anti-proliferation, anti-inflammatory and antioxidant. In addition, cinnamaldehyde also acts as a reactive oxygen species scavenger, reducing oxidative stress and preventing DNA damage and genomic instability. This article emphasizes the promising therapeutic potential of cinnamaldehyde in cancer treatment and underscores the need for future research to unlock novel mechanisms and strategies for combating cancer. By providing valuable insights into the role and mechanism of cinnamaldehyde in cancer, this comprehensive understanding paves the way for its potential as a novel therapeutic agent. Overall, cinnamaldehyde holds great promise as an anticancer agent, and its comprehensive exploration in this article highlights its potential as a valuable addition to cancer treatment options.

RNAi mediated silencing of STAT3/PD-L1 in tumor-associated immune cells induces robust anti-tumor effects in immunotherapy resistant tumors

Malignant tumors are often associated with an immunosuppressive tumor microenvironment (TME), rendering most of them resistant to standard-of-care immune checkpoint inhibitors (CPIs). Signal transducer and activator of transcription 3 (STAT3), a ubiquitously expressed transcription factor, has well-defined immunosuppressive functions in several leukocyte populations within the TME. Since the STAT3 protein has been challenging to target using conventional pharmaceutical modalities, we investigated the feasibility of applying systemically delivered RNA interference (RNAi) agents to silence its mRNA directly in tumor-associated immune cells. In preclinical rodent tumor models, chemically stabilized acylated small interfering RNAs (siRNAs) selectively silenced Stat3 mRNA in multiple relevant cell types, reduced STAT3 protein levels, and increased cytotoxic T cell infiltration. In a murine model of CPI-resistant pancreatic cancer, RNAi-mediated Stat3 silencing resulted in tumor growth inhibition, which was further enhanced in combination with CPIs. To further exemplify the utility of RNAi for cancer immunotherapy, this technology was used to silence Cd274, the gene encoding the immune checkpoint protein programmed death-ligand 1 (PD-L1). Interestingly, silencing of Cd274 was effective in tumor models that are resistant to PD-L1 antibody therapy. These data represent the first demonstration of systemic delivery of RNAi agents to the TME and suggest applying this technology for immuno-oncology applications.

Early life vaccination reprograms the metabolism and function of myeloid cells in neonates

Vaccination after birth provides protection against pathogen infection and immune related disorders in healthy children. The detailed effects of vaccination on neonatal immunity, however, remain largely unknown. Here, we reported that vaccination using Bacillus Calmette-Guérin (BCG) diminished the immunosuppressive function of myeloid-derived suppressor cells in neonatal mice, an immature myeloid population. A combination of single-cell transcriptome, metabolite profiling, and functional analysis demonstrated that upregulation of mTOR/HIF1a signalling and the enhanced glycolysis explained the effects of BCG on neonatal myeloid cells. Pharmalogical inhibition of glycolysis or mTOR signalling efficiently rescued the effects of BCG on neonatal myeloid cells. These observations suggest that BCG facilitates the maturation of myeloid cells in early life, which may contribute to its beneficial effects against immune disorders later in life.

The inositol-requiring enzyme 1 (IRE1) endoplasmic reticulum stress pathway promotes MDA-MB-231 cell survival and renewal in response to the aryl-ureido fatty acid CTU

Current treatment options for triple-negative breast cancer (TNBC) are limited to toxic drug combinations of low efficacy. We recently identified an aryl-substituted fatty acid analogue, termed CTU, that effectively killed TNBC cells in vitro and in mouse xenograft models in vivo without producing toxicity. However, there was a residual cell population that survived treatment. The present study evaluated the mechanisms that underlie survival and renewal in CTU-treated MDA-MB-231 TNBC cells. RNA-seq profiling identified several pro-inflammatory signaling pathways that were activated in treated cells. Increased expression of cyclooxygenase-2 and the cytokines IL-6, IL-8 and GM-CSF was confirmed by real-time RT-PCR, ELISA and Western blot analysis. Increased self-renewal was confirmed using the non-adherent, in vitro colony-forming mammosphere assay. Neutralizing antibodies to IL-6, IL-8 and GM-CSF, as well as cyclooxygenase-2 inhibition suppressed the self-renewal of MDA-MB-231 cells post-CTU treatment. IPA network analysis identified major NF-κB and XBP1 gene networks that were activated by CTU; chemical inhibitors of these pathways and esiRNA knock-down decreased the production of pro-inflammatory mediators. NF-κB and XBP1 signaling was in turn activated by the endoplasmic reticulum (ER)-stress sensor inositol-requiring enzyme 1 (IRE1), which mediates the unfolded protein response. Co-treatment with an inhibitor of IRE1 kinase and RNase activities, decreased phospho-NF-κB and XBP1s expression and the production of pro-inflammatory mediators. Further, IRE1 inhibition also enhanced apoptotic cell death and prevented the activation of self-renewal by CTU. Taken together, the present findings indicate that the IRE1 ER-stress pathway is activated by the anti-cancer lipid analogue CTU, which then activates secondary self-renewal in TNBC cells.

MDSC-targeting gold nanoparticles enhance PD-1 tumor immunotherapy by inhibiting NLRP3 inflammasomes

Myeloid-derived suppressor cells (MDSCs) play a crucial role in the immune escape mechanisms that limit the efficacy of immunotherapeutic strategies. In the tumor microenvironment, NLRP3 inflammasome-driven Interleukin-1β (IL-1β) production serves to dampen antitumor immune responses, promoting tumor growth, progression, and immunosuppression. In this study, we revealed that gold nanoparticles (Au NPs) with a size of 30 nm disrupted NLRP3 inflammasome, but not other inflammasomes, in bone marrow-derived macrophages through abrogating NLRP3-NEK7 interactions mediated by reactive oxygen species (ROS). Density functional theory (DFT) calculations provided insights into the mechanism underlying the exceptional ROS scavenging capabilities of Au NPs. Additionally, when coupled with H6, a small peptide targeting MDSCs, Au NPs demonstrated the capacity to effectively reduce IL-1β levels and diminish the MDSCs population in tumor microenvironment, leading to enhanced T cell activation and increased immunotherapeutic efficacy in mouse tumor models that are sensitive and resistant to PD-1 inhibition. Our findings unraveled a novel approach wherein peptide-modified Au NPs relieved the suppressive impact of the tumor microenvironment by inhibiting MDSCs-mediated IL-1β release, which is the first time reported the employing a nanostrategy at modulating MDSCs to reverse the immunosuppressive microenvironment and may hold promise as a potential therapeutic agent for cancer immunotherapy.

β-Glucan Subverts the Function of Myeloid Cells in Neonates

β-Glucan is the main component of the cell wall of pathogen-associated molecular patterns (PAMPs) including various yeast, fungi, or certain bacteria. Previous reports demonstrated that β-glucan was widely investigated as a potent immunomodulators to stimulate innate and adaptive immune responses, which indicated that it could be recommended as an effective adjuvant in immunotherapy. However, the detailed effects of β-glucan on neonatal immunity are still largely unknown. Here, we found that β-glucan did not affect the frequencies and numbers of myeloid cells in the spleen and bone marrow from neonates. Functional assay revealed that β-glucan from neonates compromised the immunosuppressive function of immature myeloid cells, which were myeloid-derived suppressor cells (MDSCs). Flow cytometry or gene expression analysis revealed that β-glucan-derived polymorphonuclear (PMN)-MDSCs produced lower level of reactive oxygen species (ROS) and arginase-1 (Arg1) in neonatal mice. Furthermore, β-glucan administration significantly decreased the frequency and ROS level of PMN-MDSCs in vitro. These observations suggest that β-glucan facilitates the maturation of myeloid cells in early life, which may contribute to its beneficial effects against immune disorders later in life.

Key players of immunosuppression in epithelial malignancies: Tumor-infiltrating myeloid cells and γδ T cells

BACKGROUND

The tumor microenvironment of solid tumors governs the differentiation of otherwise non-immunosuppressive macrophages and gamma delta (γδ) T cells into strong immunosuppressors while promoting suppressive abilities of known immunosuppressors such as myeloid-derived suppressor cells (MDSCs) upon infiltration into the tumor beds.

RECENT FINDINGS

In epithelial malignancies, tumor-associated macrophages (TAMs), precursor monocytic MDSCs (M-MDSCs), and gamma delta (γδ) T cells often acquire strong immunosuppressive abilities that dampen spontaneous immune responses by tumor-infiltrating T cells and B lymphocytes against cancer. Both M-MDSCs and γδ T cells have been associated with worse prognosis for multiple epithelial cancers.

CONCLUSION

Here we discuss recent discoveries on how tumor-associated macrophages and precursor M-MDSCs as well as tumor associated-γδ T cells acquire immunosuppressive abilities in the tumor beds, promote cancer metastasis, and perspectives on how possible novel interventions could restore the effective adaptive immune responses in epithelial cancers.

Dendritic cell-derived exosome (DEX) therapy for digestive system cancers: Recent advances and future prospect

Tumor-mediated immunosuppression is a fundamental obstacle to the development of dendritic cell (DC)-based cancer vaccines, which despite their ability to stimulate host anti-tumor CD8 T cell immunity, have not been able to generate meaningful therapeutic responses. Exosomes are inactive membrane vesicles that are nanoscale in size and are produced by the endocytic pathway. They are essential for intercellular communication. Additionally, DC-derived exosomes (DEXs) contained MHC class I/II (MHCI/II), which is frequently complexed with antigens and co-stimulatory molecules and is therefore able to prime CD4 and CD8 T cells that are specific to particular antigens. Indeed, vaccines with DEXs have been shown to exhibit better anti-tumor efficacy in eradicating tumors compared to DC vaccines in pre-clinical models of digestive system tumors. Also, there is room for improvement in the tumor antigenic peptide (TAA) selection process. DCs release highly targeted exosomes when the right antigenic peptide is chosen, which could aid in the creation of DEX-based antitumor vaccines that elicit more targeted immune responses. Coupled with their resistance to tumor immunosuppression, DEXs-based cancer vaccines have been heralded as the superior alternative cell-free therapeutic vaccines over DC vaccines to treat digestive system tumors. In this review, current studies of DEXs cancer vaccines as well as potential future directions will be deliberated.

Heterogeneity, crosstalk, and targeting of cancer-associated fibroblasts in cholangiocarcinoma

Cholangiocarcinoma (CCA) comprises diverse tumors of the biliary tree and is characterized by late diagnosis, short-term survival, and chemoresistance. CCAs are mainly classified according to their anatomical location and include diverse molecular subclasses harboring inter-tumoral and intratumoral heterogeneity. Besides the tumor cell component, CCA is also characterized by a complex and dynamic tumor microenvironment where tumor cells and stromal cells crosstalk in an intricate network of interactions. Cancer-associated fibroblasts, one of the most abundant cell types in the tumor stroma of CCA, are actively involved in cholangiocarcinogenesis by participating in multiple aspects of the disease including extracellular matrix remodeling, immunomodulation, neo-angiogenesis, and metastasis. Despite their overall tumor-promoting role, recent evidence indicates the presence of transcriptional and functional heterogeneous CAF subtypes with tumor-promoting and tumor-restricting properties. To elucidate the complexity and potentials of cancer-associated fibroblasts as therapeutic targets in CCA, this review will discuss the origin of cancer-associated fibroblasts, their heterogeneity, crosstalk, and role during tumorigenesis, providing an overall picture of the present and future perspectives toward cancer-associated fibroblasts targeting CCA.

Fine tuning of the innate and adaptive immune responses by Interleukin-2

Novel immunotherapies for cancer and other diseases aim to trigger the immune system to produce durable responses, while overcoming the immunosuppression that may contribute to disease severity, and in parallel considering immunosafety aspects. Interleukin-2 (IL-2) was one of the first cytokines that the FDA approved as a cancer-targeting immunotherapy. However, in the past years, IL-2 immunotherapy is not actively offered to patients, due to limited efficacy, when compared to other novel immunotherapies, and the associated severe adverse events. In order to design improved in vitro and in vivo models, able to predict the efficacy and safety of novel IL-2 alternatives, it is important to delineate the mechanistic immunological events triggered by IL-2. Particularly, in this review we will discuss the effects IL-2 has with the bridging cell type of the innate and adaptive immune responses, dendritic cells. The pathways involved in the regulation of IL-2 by dendritic cells and T-cells in cancer and autoimmune disease will also be explored.

Immune modulation in malignant pleural effusion: from microenvironment to therapeutic implications

Immune microenvironment and immunotherapy have become the focus and frontier of tumor research, and the immune checkpoint inhibitors has provided novel strategies for tumor treatment. Malignant pleural effusion (MPE) is a common end-stage manifestation of lung cancer, malignant pleural mesothelioma and other thoracic malignancies, which is invasive and often accompanied by poor prognosis, affecting the quality of life of affected patients. Currently, clinical therapy for MPE is limited to pleural puncture, pleural fixation, catheter drainage, and other palliative therapies. Immunization is a new direction for rehabilitation and treatment of MPE. The effusion caused by cancer cells establishes its own immune microenvironment during its formation. Immune cells, cytokines, signal pathways of microenvironment affect the MPE progress and prognosis of patients. The interaction between them have been proved. The relevant studies were obtained through a systematic search of PubMed database according to keywords search method. Then through screening and sorting and reading full-text, 300 literatures were screened out. Exclude irrelevant and poor quality articles, 238 literatures were cited in the references. In this study, the mechanism of immune microenvironment affecting malignant pleural effusion was discussed from the perspectives of adaptive immune cells, innate immune cells, cytokines and molecular targets. Meanwhile, this study focused on the clinical value of microenvironmental components in the immunotherapy and prognosis of malignant pleural effusion.

Preimmunization with Listeria-vectored cervical cancer vaccine candidate strains can establish specific T-cell immune memory and prevent tumorigenesis

BACKGROUND

Although HPV prophylactic vaccines can provide effective immune protection against high-risk HPV infection, studies have shown that the protective effect provided by them would decrease with the increased age of vaccination, and they are not recommended for those who are not in the appropriate age range for vaccination. Therefore, in those people who are not suitable for HPV prophylactic vaccines, it is worth considering establishing memory T-cell immunity to provide long-term immune surveillance and generate a rapid response against lesional cells to prevent tumorigenesis.

METHODS

In this study, healthy mice were preimmunized with LM∆E6E7 and LI∆E6E7, the two Listeria-vectored cervical cancer vaccine candidate strains constructed previously by our laboratory, and then inoculated with tumor cells 40 d later.

RESULTS

The results showed that preimmunization with LM∆E6E7 and LI∆E6E7 could establish protective memory T-cell immunity against tumor antigens in mice, which effectively eliminate tumor cells. 60% of mice preimmunized with vaccines did not develop tumors, and for the remaining mice, tumor growth was significantly inhibited. We found that preimmunization with vaccines may exert antitumor effects by promoting the enrichment of T cells at tumor site to exert specific immune responses, as well as inhibiting intratumoral angiogenesis and cell proliferation.

CONCLUSION

Altogether, this study suggests that preimmunization with LM∆E6E7 and LI∆E6E7 can establish memory T-cell immunity against tumor antigens in vivo, which provides a viable plan for preventing tumorigenesis and inhibiting tumor progression.

Tissue contexture determines the pattern and density of tumor-infiltrating immune cells in HPV-associated squamous cell carcinomas of oropharynx and uterine cervix

The profile of the antitumor immune response is an important factor determining patient clinical outcome. However, the influence of the tissue contexture on the composition of the tumor microenvironments of virally induced tumors is not clearly understood. Therefore, we analyzed the immune landscape of two HPV-associated malignancies: oropharyngeal squamous cell carcinoma (OPSCC) and squamous cell carcinoma of uterine cervix (CESC). We employed multiplex immunohistochemistry and immunofluorescence to evaluate the density and spatial distribution of immune cells in retrospective cohorts of OPSCC and CESC patients. This approach was complemented by transcriptomic analysis of purified primary tumor cells and in silico analysis of publicly available RNA sequencing data. Transcriptomic analysis showed similar immune profiles in OPSCC and CESC samples. Interestingly, immunostaining of OPSCC tissues revealed high densities of immune cells in both tumor stroma and tumor epithelium, whereas CESC samples were mainly characterized by the lack of immune cells in the tumor epithelium. However, in contrast to other immune cell populations, polymorphonuclear myeloid-derived suppressor cells (PMN-MDSCs) were abundant in both segments of CESC samples and CESC-derived tumor cells expressed markedly higher levels of the PMN-MDSC chemoattractants CXCL1, CXCL5, and CXCL6 than OPSCC tumor cells. Taken together, despite their having the same etiologic agent, the immune infiltration pattern significantly differs between OPSCC and CESC, with a noticeable shift toward prominent MDSC infiltration in the latter. Our data thus present a rationale for a diverse approach to targeted therapy in patients with HPV-associated tumors of different tissue origins.

The paradoxical role of cytokines and chemokines at the tumor microenvironment: a comprehensive review

Tumor progression and eradication have long piqued the scientific community's interest. Recent discoveries about the role of chemokines and cytokines in these processes have fueled renewed interest in related research. These roles are frequently viewed as contentious due to their ability to both suppress and promote cancer progression. As a result, this review critically appraised existing literature to discuss the unique roles of cytokines and chemokines in the tumor microenvironment, as well as the existing challenges and future opportunities for exploiting these roles to develop novel and targeted treatments. While these modulatory molecules play an important role in tumor suppression via enhanced cancer-cell identification by cytotoxic effector cells and directly recruiting immunological effector cells and stromal cells in the TME, we observed that they also promote tumor proliferation. Many cytokines, including GM-CSF, IL-7, IL-12, IL-15, IL-18, and IL-21, have entered clinical trials for people with advanced cancer, while the FDA has approved interferon-alpha and IL-2. Nonetheless, low efficacy and dose-limiting toxicity limit these agents' full potential. Conversely, Chemokines have tremendous potential for increasing cancer immune-cell penetration of the tumor microenvironment and promoting beneficial immunological interactions. When chemokines are combined with cytokines, they activate lymphocytes, producing IL-2, CD80, and IL-12, all of which have a strong anticancer effect. This phenomenon opens the door to the development of effective anticancer combination therapies, such as therapies that can reverse cancer escape, and chemotaxis of immunosuppressive cells like Tregs, MDSCs, and TAMs.

Immunotherapy Innovations in the Fight against Osteosarcoma: Emerging Strategies and Promising Progress

Immunosuppressive elements within the tumor microenvironment are the primary drivers of tumorigenesis and malignant advancement. The presence, as well as the crosstalk between myeloid-derived suppressor cells (MDSCs), osteosarcoma-associated macrophages (OS-Ms), regulatory T cells (Tregs), and endothelial cells (ECs) with osteosarcoma cells cause the poor prognosis of OS. In addition, the consequent immunosuppressive factors favor the loss of treatment potential. Nanoparticles offer a means to dynamically and locally manipulate immuno-nanoparticles, which present a promising strategy for transforming OS-TME. Additionally, chimeric antigen receptor (CAR) technology is effective in combating OS. This review summarizes the essential mechanisms of immunosuppressive cells in the OS-TME and the current immune-associated strategies. The last part highlights the limitations of existing therapies and offers insights into future research directions.

Adoptive cell therapy for high grade gliomas using simultaneous temozolomide and intracranial mgmt-modified γδ t cells following standard post-resection chemotherapy and radiotherapy: current strategy and future directions

Cellular therapies, including chimeric antigen receptor T cell therapies (CAR-T), while generally successful in hematologic malignancies, face substantial challenges against solid tumors such as glioblastoma (GBM) due to rapid growth, antigen heterogeneity, and inadequate depth of response to cytoreductive and immune therapies, We have previously shown that GBM constitutively express stress associated NKG2D ligands (NKG2DL) recognized by gamma delta (γδ) T cells, a minor lymphocyte subset that innately recognize target molecules via the γδ T cell receptor (TCR), NKG2D, and multiple other mechanisms. Given that NKG2DL expression is often insufficient on GBM cells to elicit a meaningful response to γδ T cell immunotherapy, we then demonstrated that NKG2DL expression can be transiently upregulated by activation of the DNA damage response (DDR) pathway using alkylating agents such as Temozolomide (TMZ). TMZ, however, is also toxic to γδ T cells. Using a p140K/MGMT lentivector, which confers resistance to TMZ by expression of O(6)-methylguanine-DNA-methyltransferase (MGMT), we genetically engineered γδ T cells that maintain full effector function in the presence of therapeutic doses of TMZ. We then validated a therapeutic system that we termed Drug Resistance Immunotherapy (DRI) that combines a standard regimen of TMZ concomitantly with simultaneous intracranial infusion of TMZ-resistant γδ T cells in a first-in-human Phase I clinical trial (NCT04165941). This manuscript will discuss DRI as a rational therapeutic approach to newly diagnosed GBM and the importance of repeated administration of DRI in combination with the standard-of-care Stupp regimen in patients with stable minimal residual disease.

Experimental and clinical evidence in favour of an effective immune stimulation in ER-positive, endocrine-dependent metastatic breast cancer

In ER+ breast cancer, usually seen as the low immunogenic type, the main mechanisms favouring the immune response or tumour growth and immune evasion in the tumour microenvironment (TME) have been examined. The principal implications of targeting the oestrogen-mediated pathways were also considered. Recent experimental findings point out that anti-oestrogens contribute to the reversion of the immunosuppressive TME. Moreover, some preliminary clinical data with the hormone-immunotherapy association in a metastatic setting support the notion that the reversion of immune suppression in TME is likely favoured by the G0-G1 state induced by anti-oestrogens. Following immune stimulation, the reverted immune suppression allows the boosting of the effector cells of the innate and adaptive immune response. This suggests that ER+ breast cancer is a molecular subtype where a successful active immune manipulation can be attained. If this is confirmed by a prospective multicentre trial, which is expected in light of the provided evidence, the proposed hormone immunotherapy can also be tested in the adjuvant setting. Furthermore, the different rationale suggests a synergistic activity of our proposed immunotherapy with the currently recommended regimen consisting of antioestrogens combined with cyclin kinase inhibitors. Overall, this lays the foundation for a shift in clinical practice within this most prevalent molecular subtype of breast cancer.

Pathological complete response to neoadjuvant therapy with serplulimab and chemotherapy in stage IIIB small cell lung cancer: a case report and literature review

Chemotherapy combined with immunotherapy has significantly improved survival in patients with extensive-stage small cell lung cancer (ES-SCLC), and neoadjuvant immunotherapy combined with chemotherapy has emerged as the standard treatment for those with resectable non-small cell lung cancer (NSCLC). However, the potential benefits of surgery following neoadjuvant immunotherapy combined with chemotherapy in locally advanced SCLC remain unclear. Herein, we report a patient diagnosed with stage IIIB SCLC, who was administered five cycles of neoadjuvant serplulimab combined with chemotherapy followed by surgery, and subsequently achieved a pathologic complete response (pCR). Within a follow-up duration of six months, the patient displayed neither recurrence nor metastasis and experienced no treatment-related adverse reactions of any grade. Based on this case, for locally advanced SCLC, neoadjuvant serplulimab combined with chemotherapy followed by surgery may present an effective, safe, and potentially curative treatment strategy. Nonetheless, further prospective studies are needed to verify our findings.

Progress in mechanism-based diagnosis and treatment of tuberculosis comorbid with tumor

Tuberculosis (TB) and tumor, with similarities in immune response and pathogenesis, are diseases that are prone to produce autoimmune stress response to the host immune system. With a symbiotic relationship between the two, TB can facilitate the occurrence and development of tumors, while tumor causes TB reactivation. In this review, we systematically sorted out the incidence trends and influencing factors of TB and tumor, focusing on the potential pathogenesis of TB and tumor, to provide a pathway for the co-pathogenesis of TB comorbid with tumor (TCWT). Based on this, we summarized the latest progress in the diagnosis and treatment of TCWT, and provided ideas for further exploration of clinical trials and new drug development of TCWT.

Immune Escape Strategies in Head and Neck Cancer: Evade, Resist, Inhibit, Recruit

Head and neck cancers (HNCs) arise from the mucosal lining of the aerodigestive tract and are often associated with alcohol use, tobacco use, and/or human papillomavirus (HPV) infection. Over 600,000 new cases of HNC are diagnosed each year, making it the sixth most common cancer worldwide. Historically, treatments have included surgery, radiation, and chemotherapy, and while these treatments are still the backbone of current therapy, several immunotherapies have recently been approved by the Food and Drug Administration (FDA) for use in HNC. The role of the immune system in tumorigenesis and cancer progression has been explored since the early 20th century, eventually coalescing into the current three-phase model of cancer immunoediting. During each of the three phases-elimination, equilibrium, and escape-cancer cells develop and utilize multiple strategies to either reach or remain in the final phase, escape, at which point the tumor is able to grow and metastasize with little to no detrimental interference from the immune system. In this review, we summarize the many strategies used by HNC to escape the immune system, which include ways to evade immune detection, resist immune cell attacks, inhibit immune cell functions, and recruit pro-tumor immune cells.

Analysis of Changes in Plasma Cytokine Levels in Response to IL12 Therapy in Three Clinical Trials

The ability of IL12 to stimulate natural killer (NK) cell and T-cell antitumor activity makes it an attractive candidate for the immune therapy of cancer. Our group has demonstrated that IL12 enhances the NK cell response to antibody-coated tumor cells and conducted three clinical trials utilizing IL12 with mAbs (OSU-9968, OSU-0167, and OSU-11010). To better characterize IL12-induced immunity, plasma cytokine levels were measured in 21 patients from these trials with favorable and unfavorable responses. t-statistics and linear modeling were used to test for differences within and between response groups by examining levels at baseline and post-IL12 administration. Patients exhibited significant increases in 11 cytokines post-IL12 administration when analyzed collectively. However, several cytokines were differentially induced by IL12 depending on response. GMCSF was significantly increased in complete/partially responding patients, while stable disease patients had significant increases in IL10 and decreases in VEGF-C. Patients who experienced progressive disease had significant increases in CCL3, CCL4, IL18, TNFα, CXCL10, CCL8, CCL2, IL6, and IFNγ. The increases in CCL3, CCL4, and IL6 in progressive disease patients were significantly higher than in clinically benefitting patients and most prominent within the first two cycles of IL12 therapy. This correlative pilot study has identified changes that occur in levels of circulating cytokines following IL12 administration to patients with cancer, but this report must be viewed as exploratory in nature. It is meant to spark further inquiry into the topic via the analysis of additional cohorts of patients with similar characteristics who have received IL12 in a uniform fashion.

SIGNIFICANCE

IL12 activates immune cells and is used to treat cancer. The profile of circulating cytokines was measured in an exploratory fashion in patients with cancer that received IL12 in combination with mAbs. This correlative pilot study could serve as the basis for additional studies of IL12 effects on the production of immune cytokines.

Vdelta1 T cells are more resistant than Vdelta2 T cells to the immunosuppressive properties of galectin-3

Ovarian carcinomas have the highest lethality amongst gynecological tumors. A problem after primary resection is the recurrence of epithelial ovarian carcinomas which is often associated with chemotherapy resistance. To improve the clinical outcome, it is of high interest to consider alternative therapy strategies. Due to their pronounced plasticity, γδ T cells are attractive for T-cell-based immunotherapy. However, tumors might escape by the release of lectin galectin-3, which impairs γδ T-cell function. Hence, we tested the effect of galectin-3 on the different γδ T-cell subsets. After coculture between ovarian tumor cells and Vδ1 or Vδ2 T cells enhanced levels of galectin-3 were released. This protein did not affect the cytotoxicity of both γδ T-cell subsets, but differentially influenced the proliferation of the two γδ T-cell subsets. While increased galectin-3 levels and recombinant galectin-3 inhibited the proliferation of Vδ2 T cells, Vδ1 T cells were unaffected. In contrast to Vδ1 T cells, the Vδ2 T cells strongly upregulated the galectin-3 binding partner α3β1-integrin after their activation correlating with the immunosuppressive properties of galectin-3. In addition, galectin-3 reduced the effector memory compartment of zoledronate-activated Vδ2 T cells. Therefore, our data suggest that an activation of Vδ1 T-cell proliferation as part of a T-cell-based immunotherapy can be of advantage.

Ginsenoside Rg3: A Review of its Anticancer Mechanisms and Potential Therapeutic Applications

BACKGROUND

Traditional Chinese Medicine (TCM) has a long history of treating various diseases and is increasingly being recognized as a complementary therapy for cancer. A promising natural compound extracted from the Chinese herb ginseng is ginsenoside Rg3, which has demonstrated significant anticancer effects. It has been tested in a variety of cancers and tumors and has proven to be effective in suppressing cancer.

OBJECTIVES

This work covers various aspects of the role of ginsenoside Rg3 in cancer treatment, including its biological functions, key pathways, epigenetics, and potential for combination therapies, all of which have been extensively researched and elucidated. The study aims to provide a reference for future research on ginsenoside Rg3 as an anticancer agent and a support for the potential application of ginsenoside Rg3 in cancer treatment.

Measurement of Metabolic Alteration in Immune Cells Under Hypoxia

The hypoxic microenvironment in solid tumors affects the metabolism of tumor cells and infiltrating immune cells, which aids in robust tumor growth and expansion. Myeloid-derived suppressor cells (MDSCs) are heterogenous immature myeloid cells in the TME, which play an essential role in immune evasion by subverting T/NK cell-mediated killing. The immunosuppressive function of MDSCs is tightly regulated to the metabolic pathways, in which hypoxia plays a critical role. In this chapter, we describe the isolation of murine MDSCs from bone marrows and the measurement of the transcriptomic changes of essential metabolic enzymes under hypoxic conditions. This method can be applied to study MDSCs function, mimicking the hypoxic environment in vitro. This method can be utilized to investigate the critical metabolic alterations under a given tumor context and help evaluate the efficacy of metabolic-targeted therapies in the long run.

Inflammation-Associated Cytotoxic Agents in Tumorigenesis

Chronic inflammatory processes are related to all stages of tumorigenesis. As inflammation is closely associated with the activation and release of different cytotoxic agents, the interplay between cytotoxic agents and antagonizing principles is highlighted in this review to address the question of how tumor cells overcome the enhanced values of cytotoxic agents in tumors. In tumor cells, the enhanced formation of mitochondrial-derived reactive species and elevated values of iron ions and free heme are antagonized by an overexpression of enzymes and proteins, contributing to the antioxidative defense and maintenance of redox homeostasis. Through these mechanisms, tumor cells can even survive additional stress caused by radio- and chemotherapy. Through the secretion of active agents from tumor cells, immune cells are suppressed in the tumor microenvironment and an enhanced formation of extracellular matrix components is induced. Different oxidant- and protease-based cytotoxic agents are involved in tumor-mediated immunosuppression, tumor growth, tumor cell invasion, and metastasis. Considering the special metabolic conditions in tumors, the main focus here was directed on the disturbed balance between the cytotoxic agents and protective mechanisms in late-stage tumors. This knowledge is mandatory for the implementation of novel anti-cancerous therapeutic approaches.

ROS regulation in gliomas: implications for treatment strategies

Gliomas are one of the most common primary malignant tumours of the central nervous system (CNS), of which glioblastomas (GBMs) are the most common and destructive type. The glioma tumour microenvironment (TME) has unique characteristics, such as hypoxia, the blood-brain barrier (BBB), reactive oxygen species (ROS) and tumour neovascularization. Therefore, the traditional treatment effect is limited. As cellular oxidative metabolites, ROS not only promote the occurrence and development of gliomas but also affect immune cells in the immune microenvironment. In contrast, either too high or too low ROS levels are detrimental to the survival of glioma cells, which indicates the threshold of ROS. Therefore, an in-depth understanding of the mechanisms of ROS production and scavenging, the threshold of ROS, and the role of ROS in the glioma TME can provide new methods and strategies for glioma treatment. Current methods to increase ROS include photodynamic therapy (PDT), sonodynamic therapy (SDT), and chemodynamic therapy (CDT), etc., and methods to eliminate ROS include the ingestion of antioxidants. Increasing/scavenging ROS is potentially applicable treatment, and further studies will help to provide more effective strategies for glioma treatment.

Influence of Housing Temperature and Genetic Diversity on Allogeneic T Cell-Induced Tissue Damage in Mice

The objective of this study was to determine how housing temperature and genetic diversity affect the onset and severity of allogeneic T cell-induced tissue damage in mice subjected to reduced intensity conditioning (RIC). We found that adoptive transfer of allogeneic CD4+ T cells from inbred donors into sub-lethally irradiated inbred recipients (I→I) housed at standard housing temperatures (ST; 22-24 °C) induced extensive BM and spleen damage in the absence of injury to any other tissue. Although engraftment of T cells in RIC-treated mice housed at their thermo-neutral temperature (TNT; 30-32 °C) also developed similar BM and spleen damage, their survival was markedly and significantly increased when compared to their ST counterparts. In contrast, the adoptive transfer of allogeneic T cells into RIC-treated outbred CD1 recipients failed to induce disease in any tissue at ST or TNT. The lack of tissue damage was not due to defects in donor T cell trafficking to BM or spleen but was associated with the presence of large numbers of B cells and myeloid cells within these tissues that are known to contain immunosuppressive regulatory B cells and myeloid-derived suppressor cells. These data demonstrate, for the first time, that housing temperature affects the survival of RIC-treated I→I mice and that RIC-conditioned outbred mice are resistant to allogeneic T cell-induced BM and spleen damage.

TMPRSS11D/ALR-mediated ER stress regulates the function of myeloid-derived suppressor cells in the cervical cancer microenvironment

Myeloid-derived suppressor cells (MDSCs) contribute to tumor immune evasion, and have been identified as immunosuppressive cells in cervical cancer. The effect of TMPRSS11D (transmembrane serine protease 11D) in some cancers has been reported, but its role in immune escape of cervical cancer is still unclear. This study aims to elucidate the regulatory mechanism of TMPRSS11D on the immunosuppressive function of MDSCs in cervical cancer. Our data showed that the proportion of polymorphonucleoid MDSCs (PMN-MDSCs), the contents of immunosuppressive factors (including INOS, IDO, and ARG-1) secreted by MDSCs, and TMPRSS11D mRNA level in peripheral blood mononuclear cells (PBMCs) of malignant cervical cancer patients was significantly higher than that of benign tumor patients. Next, CD3+ T cells from PBMCs of cervical cancer patients were stimulated with anti-CD3 and anti-CD28, and then co-cultured with PMN-MDSCs from the same donors at a ratio of 1:2 for 3 days. PMN-MDSCs from malignant tumors produced more ROS, while TMPRSS11D knockdown blocked ROS production. PMN-MDSCs inhibited T cell proliferation and IFN-γ production, while silencing TMPRSS11D in PMN-MDSCs hindered the immunosuppressive effect of PMN-MDSCs. Mechanistically, TMPRSS11D bound to ALR (Augmenter of liver regeneration) and negatively regulated ALR expression, inducing ER stress in PMN-MDSCs, thereby enhancing the immunosuppressive effect of PMN-MDSCs on T cells. Additionally, mouse xenograft tumor assay was conducted to assess the role of TMPRSS11D in tumor growth and MDSC accumulation in vivo. Silencing TMPRSS11D impeded the growth of cervical cancer xenografts and reduced the accumulation of MDSCs in tumor tissues. In conclusion, TMPRSS11D induced ER stress in MDSCs through negative regulation of ALR, thus enhancing the immunosuppressive effect of MDSCs on T cells, so as to promote the growth of cervical cancer tumors.

Myeloperoxidase creates a permissive microenvironmental niche for the progression of multiple myeloma

Expression of myeloperoxidase (MPO), a key inflammatory enzyme restricted to myeloid cells, is negatively associated with the development of solid tumours. Activated myeloid cell populations are increased in multiple myeloma (MM); however, the functional consequences of myeloid-derived MPO within the myeloma microenvironment are unknown. Here, the role of MPO in MM pathogenesis was investigated, and the capacity for pharmacological inhibition of MPO to impede MM progression was evaluated. In the 5TGM1-KaLwRij mouse model of myeloma, the early stages of tumour development were associated with an increase in CD11b+ myeloid cell populations and an increase in Mpo expression within the bone marrow (BM). Interestingly, MM tumour cell homing was increased towards sites of elevated myeloid cell numbers and MPO activity within the BM. Mechanistically, MPO induced the expression of key MM growth factors, resulting in tumour cell proliferation and suppressed cytotoxic T-cell activity. Notably, tumour growth studies in mice treated with a small-molecule irreversible inhibitor of MPO (4-ABAH) demonstrated a significant reduction in overall MM tumour burden. Taken together, our data demonstrate that MPO contributes to MM tumour growth, and that MPO-specific inhibitors may provide a new therapeutic strategy to limit MM disease progression.

Proteomic and single-cell analysis shed new light on the anti-inflammatory role of interferonβ in chronic periodontitis

Periodontitis, a condition that results in periodontal attachment loss and alveolar bone resorption, contributes to the global burden of oral disease. The underlying mechanism of periodontitis involves the dysbiosis and dyshomeostasis between host and oral microbes, among which the macrophage is one of the major innate immune cell players, producing interferon β (IFNβ) in response to bacterial infection. The objective of this research was to examine the interaction of macrophages with periodontitis and the role and mechanism of IFNβ on macrophages. IFNβ has been shown to have the potential to induce the differentiation of M1 to M2 macrophages, which are stimulated by low levels of lipopolysaccharide (LPS). Additionally, IFNβ has been demonstrated to promote the production of ISG15 by macrophages, which leads to the inhibition of the innate immune response. Moreover, our investigation revealed that IFNβ has the potential to augment the secretion of ISG15 and its downstream cytokine, IL10, in LPS-stimulated macrophages. Single-cell analysis was conducted on the gingival tissues of patients with periodontitis, which revealed a higher proportion of macrophages in the periodontitis-diseased tissue and increased expression of IFNβ, ISG15, and IL10. Gene Set Enrichment Analysis indicated that bacterial infection was associated with upregulation of IFNβ, ISG15, and IL10. Notably, only IL10 has been linked to immunosuppression, indicating that the IFNβ-ISG15-IL10 axis might promote an anti-inflammatory response in periodontitis through IL10 expression. It is also found that macrophage phenotype transitions in periodontitis involve the release of higher levels of IFNβ, ISG15, and IL10 by the anti-inflammatory M2 macrophage phenotype compared to the pro-inflammatory M1 phenotype and myeloid-derived suppressor cells (MDSCs). This implies that the IFNβ-induced production of IL10 might be linked to the M2 macrophage phenotype. Furthermore, cell communication analysis demonstrated that IL10 can promote fibroblast proliferation in periodontal tissues via STAT3 signaling.

The role of microbiota in esophageal squamous cell carcinoma: A review of the literature

Esophageal squamous cell carcinoma (ESCC) exhibits high incidence with poor prognosis. Alcohol drinking, cigarette smoking, and betel nut chewing are well-known risk factors. Dysbiosis, an imbalance of the microbiota residing in a local environment, is known to be associated with human diseases, especially cancer. This article reviews the current evidence of esophageal microbiota in ESCC carcinogenesis, including initiation, progression, and drug resistance. Articles involving the esophageal microbiota, diagnosis, treatment, and the progression of esophageal cancer were acquired using a comprehensive literature search in PubMed in recent 10 years. Based on 16S rRNA sequencing of human samples, cell, and animal studies, current evidence suggests dysbiosis of the esophagus promotes ESCC progression and chemotherapy resistance, leading to a poor prognosis. Smoking and drinking are associated with esophageal dysbiosis. Specific bacteria have been reported to promote carcinogenesis, involving either progression or drug resistance in ESCC, for example Porphyromonas gingivalis and Fusobacterium nucleatum. These bacteria promote ESCC cell proliferation and migration via the TLR4/NF-κB and IL-6/STAT3 pathways. F. nucleatum induces cisplatin resistance via the enrichment of immunosuppressive myeloid-derived suppressor cells (MDSCs). Correcting the dysbiosis and reducing the abundance of specific esophageal pathogens may help in suppressing cancer progression. In conclusion, esophageal dysbiosis is associated with ESCC progression and chemoresistance. Screening the oral and esophageal microbiota is a potential diagnostic tool for predicting ESCC development or drug-resistance. Repairing esophageal dysbiosis is a novel treatment for ESCC. Clinical trials with probiotics in addition to current chemotherapy are warranted to study the therapeutic effects.

CUL4B functions as a tumor suppressor in KRAS-driven lung tumors by inhibiting the recruitment of myeloid-derived suppressor cells

Lung cancer is the leading cause of cancer-related death worldwide. KRAS mutations are the most common oncogenic alterations found in lung cancer. Unfortunately, treating KRAS-mutant lung adenocarcinoma (ADC) remains a major oncotherapeutic challenge. Here, we used both autochthonous and transplantable KRAS-mutant tumor models to investigate the role of tumor-derived CUL4B in KRAS-driven lung cancers. We showed that knockout or knockdown of CUL4B promotes lung ADC growth and progression in both models. Mechanistically, CUL4B directly binds to the promoter of Cxcl2 and epigenetically represses its transcription. CUL4B deletion increases the expression of CXCL2, which binds to CXCR2 on myeloid-derived suppressor cells (MDSCs) and promotes their migration to the tumor microenvironment. Targeting of MDSCs significantly delayed the growth of CUL4B knockdown KRAS-mutant tumors. Collectively, our study provides mechanistic insights into the novel tumor suppressor-like functions of CUL4B in regulating KRAS-driven lung tumor development.

Clinical evidence for a role of E2F1-induced replication stress in modulating tumor mutational burden and immune microenvironment

DNA replication stress (RS) is frequently induced by oncogene activation and is believed to promote tumorigenesis. However, clinical evidence for the role of oncogene-induced RS in tumorigenesis remains scarce, and the mechanisms by which RS promotes cancer development remain incompletely understood. By performing a series of bioinformatic analyses on the oncogene E2F1, other RS-inducing factors, and replication fork processing factors in TCGA cancer database using previously established tools, we show that hyperactivity of E2F1 likely promotes the expression of several of these factors in virtually all types of cancer to induce RS and cytosolic self-DNA production. In addition, the expression of these factors positively correlates with that of ATR and Chk1 that govern the cellular response to RS, the tumor mutational load, and tumor infiltration of immune-suppressive CD4+Th2 cells and myeloid-derived suppressor cells (MDSCs). Consistently, high expression of these factors is associated with poor patient survival. Our study provides new insights into the role of E2F1-induced RS in tumorigenesis and suggests therapeutic approaches for E2F1-overexpressing cancers by targeting genomic instability, cytosolic self-DNA and the tumor immune microenvironment.

Immunotherapy and immunoevasion of colorectal cancer

The tremendous success of immunotherapy in clinical trials has led to its establishment as a new pillar of cancer therapy. However, little clinical efficacy has been achieved in microsatellite stable colorectal cancer (MSS-CRC), which constitutes most CRC tumors. Here, we discuss the molecular and genetic heterogeneity of CRC. We review the immune escape mechanisms, and focus on the latest advances in immunotherapy as a treatment modality for CRC. By providing a better understanding of the tumor microenvironment (TME) and the molecular mechanisms underlying immunoevasion, this review offers an insight into developing therapeutic strategies that are effective for patients with various subsets of CRC.

Pan-cancer analyses reveal GTSE1 as a biomarker for the immunosuppressive tumor microenvironment

G2 and S phase-expressed-1 (GTSE1) has been reported to be associated with poor prognosis in many cancer types. However, the knowledge of GTSE1 across 33 cancer types remains scarce, and the mechanisms by which GTSE1 promotes cancer development remain incompletely understood. R language and TIMER2.0 were used to analyze the clinical relevance of GTSE1 across > 10,000 subjects representing 33 cancer types based on the cancer genome atlas databases. The expression of GTSE1 was upregulated in almost all cancer types and hyperactivity of GTSE1 is likely to induce DNA repair response and positively correlates with the tumor mutational burden and microsatellite instability which are both promising predictive biomarkers for immunotherapy. GTSE1 was upregulated in TP53 mutation patients. Additionally, GTSE1 also positively correlates with tumor purity and tumor infiltration of immune-suppressive myeloid-derived suppressor cells. Consistently, high expression of GTSE1 is associated with poor patient survival in many cancer types. Conclusion: Our study provides new insights into the diagnostic and prognostic role of GTSE1 in cancers and suggests therapeutic approaches for GTSE1-overexpressing cancers by targeting DNA repair response, and the tumor immune microenvironment.

The recent progress of myeloid-derived suppressor cell and its targeted therapies in cancers

Myeloid-derived suppressor cells (MDSCs) are an immature group of myeloid-derived cells generated from myeloid cell precursors in the bone marrow. MDSCs appear almost exclusively in pathological conditions, such as tumor progression and various inflammatory diseases. The leading function of MDSCs is their immunosuppressive ability, which plays a crucial role in tumor progression and metastasis through their immunosuppressive effects. Since MDSCs have specific molecular features, and only a tiny amount exists in physiological conditions, MDSC-targeted therapy has become a promising research direction for tumor treatment with minimal side effects. In this review, we briefly introduce the classification, generation and maturation process, and features of MDSCs, and detail their functions under various circumstances. The present review specifically demonstrates the environmental specificity of MDSCs, highlighting the differences between MDSCs from cancer and healthy individuals, as well as tumor-infiltrating MDSCs and circulating MDSCs. Then, we further describe recent advances in MDSC-targeted therapies. The existing and potential targeted drugs are divided into three categories, monoclonal antibodies, small-molecular inhibitors, and peptides. Their targeting mechanisms and characteristics have been summarized respectively. We believe that a comprehensive in-depth understanding of MDSC-targeted therapy could provide more possibilities for the treatment of cancer.

S100A8 gene copy number and protein expression in breast cancer: associations with proliferation, histopathological grade and molecular subtypes

BACKGROUND AND AIMS

Amplification of S100A8 occurs in 10-30% of all breast cancers and has been linked to poorer prognosis. Similarly, the protein S100A8 is overexpressed in a roughly comparable proportion of breast cancers and is also found in infiltrating myeloid-lineage cells, again linked to poorer prognosis. We explore the relationship between these findings.

METHODS

We examined S100A8 copy number (CN) alterations using fluorescence in situ hybridization in 475 primary breast cancers and 117 corresponding lymph nodes. In addition, we studied S100A8 protein expression using immunohistochemistry in 498 primary breast cancers from the same cohort.

RESULTS

We found increased S100A8 CN (≥ 4) in tumor epithelial cells in 20% of the tumors, increased S100A8 protein expression in 15%, and ≥ 10 infiltrating S100A8 + polymorphonuclear cells in 19%. Both increased S100A8 CN and protein expression in cancer cells were associated with high Ki67 status, high mitotic count and high histopathological grade. We observed no association between increased S100A8 CN and S100A8 protein expression, and only a weak association (p = 0.09) between increased CN and number of infiltrating S100A8 + immune cells. Only S100A8 protein expression in cancer cells was associated with significantly worse prognosis.

CONCLUSIONS

Amplification of S100A8 does not appear to be associated with S100A8 protein expression in breast cancer. S100A8 protein expression in tumor epithelial cells identifies a subgroup of predominantly non-luminal tumors with a high mean age at diagnosis and significantly worse prognosis. Finally, S100A8 alone is not a sufficient marker to identify infiltrating immune cells linked to worse prognosis.

Enhancing immunotherapy response in melanoma: myeloid-derived suppressor cells as a therapeutic target

Despite the remarkable success of immune checkpoint inhibitors (ICIs) in melanoma treatment, resistance to them remains a substantial clinical challenge. Myeloid-derived suppressor cells (MDSCs) represent a heterogeneous population of myeloid cells that can suppress antitumor immune responses mediated by T and natural killer cells and promote tumor growth. They are major contributors to ICI resistance and play a crucial role in creating an immunosuppressive tumor microenvironment. Therefore, targeting MDSCs is considered a promising strategy to improve the therapeutic efficacy of ICIs. This Review describes the mechanism of MDSC-mediated immune suppression, preclinical and clinical studies on MDSC targeting, and potential strategies for inhibiting MDSC functions to improve melanoma immunotherapy.

Drug Repurposing for Targeting Myeloid-Derived Suppressor-Cell-Generated Immunosuppression in Ovarian Cancer: A Literature Review of Potential Candidates

The lethality of patients with ovarian cancer (OC) remains high. Current treatment strategies often do not lead to the desired outcome due to the development of therapy resistance, resulting in high relapse rates. Additionally, clinical trials testing immunotherapy against OC have failed to reach significant results to date. The OC tumor microenvironment and specifically myeloid-derived suppressor cells (MDSC) are known to generate immunosuppression and inhibit the anti-tumor immune response following immunotherapy treatment. Our review aims to characterize potential candidate treatments to target MDSC in OC through drug-repurposing. A literature search identified repurposable compounds with evidence of their suppressing the effect of MDSC. A total of seventeen compounds were withheld, of which four were considered the most promising. Lurbinectedin, metformin, celecoxib, and 5-azacytidine have reported preclinical effects on MDSC and clinical evidence in OC. They have all been approved for a different indication, characterizing them as the most promising candidates for repurposing to treat patients with OC.

Tumor Microenvironment Remodeling in Gastrointestinal Cancer: Role of miRNAs as Biomarkers of Tumor Invasion

Gastrointestinal (GI) cancers are the most frequent neoplasm, responsible for half of all cancer-related deaths. Metastasis is the leading cause of death from GI cancer; thus, studying the processes that regulate cancer cell migration is of paramount importance for the development of new therapeutic strategies. In this review, we summarize the mechanisms adopted by cancer cells to promote cell migration and the subsequent metastasis formation by highlighting the key role that tumor microenvironment components play in deregulating cellular pathways involved in these processes. We, therefore, provide an overview of the role of different microRNAs in promoting tumor metastasis and their role as potential biomarkers for the prognosis, monitoring, and diagnosis of GI cancer patients. Finally, we relate the possible use of nutraceuticals as a new strategy for targeting numerous microRNAs and different pathways involved in GI tumor invasiveness.

The immunomodulatory role of exosomal microRNA networks in the crosstalk between tumor-associated myeloid-derived suppressor cells and tumor cells

Myeloid-derived suppressor cells (MDSCs) are considered a heterogeneous group of immature myeloid cells engaging in aggressive tumor progression and metastasis in the tumor microenvironment (TME) of patients diagnosed with cancer, through downregulation of anti-tumor immune responses. Exosomes are small vesicles carrying specific cargos, including proteins, lipids, and MicroRNA (miRNAs). Such exosomal miRNAs delivered by MDSCs and tumor cells are short noncoding RNAs mediating some of the immunosuppressive characteristics of MDSCs in the TME. However, when it comes to cancer diseases, how these miRNAs interact with MDSCs and encourage MDSCs differentiation and function need further investigations. In this review, we discuss MDSC-derived exosomal miRNAs and those derived from tumor cells (TDE) could modulate anti-tumor immunity and regulate the interaction between tumor cells and MDSCs in the TME. Afterward, we focus on dividing miRNAs, as an important substance interacting with MDSCs and tumor cells in the TME, into those have an immunosuppressive or stimulating effect not only on MDSCs expansion, differentiation, and suppressive function but also on tumor evasion.

Early decrease of blood myeloid-derived suppressor cells during checkpoint inhibition is a favorable biomarker in metastatic melanoma

BACKGROUND

The need for reliable clinical biomarkers to predict which patients with melanoma will benefit from immune checkpoint blockade (ICB) remains unmet. Several different parameters have been considered in the past, including routine differential blood counts, T cell subset distribution patterns and quantification of peripheral myeloid-derived suppressor cells (MDSC), but none has yet achieved sufficient accuracy for clinical utility.

METHODS

Here, we investigated potential cellular biomarkers from clinical routine blood counts as well as several myeloid and T cell subsets, using flow cytometry, in two independent cohorts of a total of 141 patients with stage IV M1c melanoma before and during ICB.

RESULTS

Elevated baseline frequencies of monocytic MDSCs (M-MDSC) in the blood were confirmed to predict shorter overall survival (OS) (HR 2.086, p=0.030) and progression-free survival (HR 2.425, p=0.001) in the whole patient cohort. However, we identified a subgroup of patients with highly elevated baseline M-MDSC frequencies that fell below a defined cut-off during therapy and found that these patients had a longer OS that was similar to that of patients with low baseline M-MDSC frequencies. Importantly, patients with high M-MDSC frequencies exhibited a skewed baseline distribution of certain other immune cells but these did not influence patient survival, illustrating the paramount utility of MDSC assessment.

CONCLUSION

We confirmed that in general, highly elevated frequencies of peripheral M-MDSC are associated with poorer outcomes of ICB in metastatic melanoma. However, one reason for an imperfect correlation between high baseline MDSCs and outcome for individual patients may be the subgroup of patients identified here, with rapidly decreasing M-MDSCs on therapy, in whom the negative effect of high M-MDSC frequencies was lost. These findings might contribute to developing more reliable predictors of late-stage melanoma response to ICB at the individual patient level. A multifactorial model seeking such markers yielded only MDSC behavior and serum lactate dehydrogenase as predictors of treatment outcome.

Tumor-neutrophil crosstalk promotes in vitro and in vivo glioblastoma progression

Introduction

The tumor microenvironment (TME) of glioblastoma (GB) is characterized by an increased infiltration of immunosuppressive cells that attenuate the antitumor immune response. The participation of neutrophils in tumor progression is still controversial and a dual role in the TME has been proposed. In this study, we show that neutrophils are reprogrammed by the tumor to ultimately promote GB progression.

Methods

Using in vitro and in vivo assays, we demonstrate the existence of bidirectional GB and neutrophil communication, directly promoting an immunosuppressive TME.

Results and discussion

Neutrophils have shown to play an important role in tumor malignancy especially in advanced 3D tumor model and Balb/c nude mice experiments, implying a time- and neutrophil concentration-dependent modulation. Studying the tumor energetic metabolism indicated a mitochondria mismatch shaping the TME secretome. The given data suggests a cytokine milieu in patients with GB that favors the recruitment of neutrophils, sustaining an anti-inflammatory profile which is associated with poor prognosis. Besides, glioma-neutrophil crosstalk has sustained a tumor prolonged activation via NETs formation, indicating the role of NFκB signaling in tumor progression. Moreover, clinical samples have indicated that neutrophil-lymphocyte ratio (NLR), IL-1β, and IL-10 are associated with poor outcomes in patients with GB.

Conclusion

These results are relevant for understanding how tumor progression occurs and how immune cells can help in this process.

p140Cap inhibits β-Catenin in the breast cancer stem cell compartment instructing a protective anti-tumor immune response

The p140Cap adaptor protein is a tumor suppressor in breast cancer associated with a favorable prognosis. Here we highlight a function of p140Cap in orchestrating local and systemic tumor-extrinsic events that eventually result in inhibition of the polymorphonuclear myeloid-derived suppressor cell function in creating an immunosuppressive tumor-promoting environment in the primary tumor, and premetastatic niches at distant sites. Integrative transcriptomic and preclinical studies unravel that p140Cap controls an epistatic axis where, through the upstream inhibition of β-Catenin, it restricts tumorigenicity and self-renewal of tumor-initiating cells limiting the release of the inflammatory cytokine G-CSF, required for polymorphonuclear myeloid-derived suppressor cells to exert their local and systemic tumor conducive function. Mechanistically, p140Cap inhibition of β-Catenin depends on its ability to localize in and stabilize the β-Catenin destruction complex, promoting enhanced β-Catenin inactivation. Clinical studies in women show that low p140Cap expression correlates with reduced presence of tumor-infiltrating lymphocytes and more aggressive tumor types in a large cohort of real-life female breast cancer patients, highlighting the potential of p140Cap as a biomarker for therapeutic intervention targeting the β-Catenin/ Tumor-initiating cells /G-CSF/ polymorphonuclear myeloid-derived suppressor cell axis to restore an efficient anti-tumor immune response.

A Comprehensive Pan-Cancer Analysis Identifies CEP55 as a Potential Oncogene and Novel Therapeutic Target

Emerging research findings have shown that a centrosomal protein (CEP55) is a potential oncogene in numerous human malignancies. Nevertheless, no pan-cancer analysis has been conducted to investigate the various aspects and behavior of this oncogene in different human cancerous tissues. Numerous databases were investigated to conduct a detailed analysis of CEP55. Initially, we evaluated the expression of CEP55 in several types of cancers and attempted to find the correlation between that and the stage of the examined malignancies. Then, we conducted a survival analysis to determine the relationship between CEP55 overexpression in malignancies and the patient's survival. Furthermore, we examined the genetic alteration forms and the methylation status of this oncogene. Additionally, the interference of CEP55 expression with immune cell infiltration, the response to various chemotherapeutic agents, and the putative molecular mechanism of CEP55 in tumorigenesis were investigated. The current study found that CEP55 was upregulated in cancerous tissues versus normal controls where this upregulation was correlated with a poor prognosis in multiple forms of human cancers. Additionally, it influenced the level of different immune cell infiltration and several chemokines levels in the tumor microenvironment in addition to the response to several antitumor drugs. Herein, we provide an in-depth understanding of the oncogenic activities of CEP55, identifying it as a possible predictive marker as well as a specific target for developing anticancer therapies.

The Metabolic Landscape of Breast Cancer and Its Therapeutic Implications

Breast cancer is the most common malignant tumor globally as of 2020 and remains the second leading cause of cancer-related death among female individuals worldwide. Metabolic reprogramming is well recognized as a hallmark of malignancy owing to the rewiring of multiple biological processes, notably, glycolysis, oxidative phosphorylation, pentose phosphate pathway, as well as lipid metabolism, which support the demands for the relentless growth of tumor cells and allows distant metastasis of cancer cells. Breast cancer cells are well documented to reprogram their metabolism via mutations or inactivation of intrinsic factors such as c-Myc, TP53, hypoxia-inducible factor, and the PI3K/AKT/mTOR pathway or crosstalk with the surrounding tumor microenvironments, including hypoxia, extracellular acidification and interaction with immune cells, cancer-associated fibroblasts, and adipocytes. Furthermore, altered metabolism contributes to acquired or inherent therapeutic resistance. Therefore, there is an urgent need to understand the metabolic plasticity underlying breast cancer progression as well as to dictate metabolic reprogramming that accounts for the resistance to standard of care. This review aims to illustrate the altered metabolism in breast cancer and its underlying mechanisms, as well as metabolic interventions in breast cancer treatment, with the intention to provide strategies for developing novel therapeutic treatments for breast cancer.

Harnessing the Immunological Effects of Radiation to Improve Immunotherapies in Cancer

Ionizing radiation (IR) is used to treat 50% of cancers. While the cytotoxic effects related to DNA damage with IR have been known since the early 20th century, the role of the immune system in the treatment response is still yet to be fully determined. IR can induce immunogenic cell death (ICD), which activates innate and adaptive immunity against the cancer. It has also been widely reported that an intact immune system is essential to IR efficacy. However, this response is typically transient, and wound healing processes also become upregulated, dampening early immunological efforts to overcome the disease. This immune suppression involves many complex cellular and molecular mechanisms that ultimately result in the generation of radioresistance in many cases. Understanding the mechanisms behind these responses is challenging as the effects are extensive and often occur simultaneously within the tumor. Here, we describe the effects of IR on the immune landscape of tumors. ICD, along with myeloid and lymphoid responses to IR, are discussed, with the hope of shedding light on the complex immune stimulatory and immunosuppressive responses involved with this cornerstone cancer treatment. Leveraging these immunological effects can provide a platform for improving immunotherapy efficacy in the future.