Cytosolic high-mobility group box protein 1 (HMGB1) and/or PD-1+ TILs in the tumor microenvironment may be contributing prognostic biomarkers for patients with locally advanced rectal cancer who have undergone neoadjuvant chemoradiotherapy

Effects of anlotinib hydrochloride on the expression of immunogenic cell death-related molecules in Cal27 tongue cancer cells

OBJECTIVE

To investigate the effects of anlotinib hydrochloride (AL3818) on the expression of Immunogenic Cell Death (ICD)-related molecules in tongue cancer cells.

METHODS

(1) The human Tongue Squamous Cell Carcinoma (TSCC) cell line Cal27 was cultured, and the half-maximal inhibitory concentration (IC50) of AL3818 and paclitaxel (PTX) on Cal27 cells was determined using the CCK-8 assay. The cells were divided into four groups: control group, AL3818 group, PTX group, and AL3818 + PTX group; (2) The apoptosis rate of each group was measured by flow cytometry; (3) The levels of calreticulin (CRT) and heat shock protein 70 (HSP70) were detected by immunofluorescence and flow cytometry; (4) The concentration of High Mobility Group Box 1 (HMGB1) was measured by Enzyme-Linked Immunosorbent Assay (ELISA); (5) Adenosine Triphosphate (ATP) levels were assessed using an ATP luminescence assay kit; and (6) The cells were divided into the control group, AL3818 group, AL3818 + CCT020312 (perk activator) treatment group, and AL3818 + ISRIB (perk inhibitor) treatment group, and detect the relative expression levels of total CRT, membrane-bound CRT, p-perk, and p-eIF2a in each group using the western blot method.

RESULTS

(1) The IC50 values of AL3818 and PTX at 24 h were 6.254 μmol/L and 1.718 μmol/L, respectively (P < 0.01); (2) AL3818 and PTX induced apoptosis in Cal27 cells (P < 0.05), with the highest apoptosis rate observed in the AL3818 + PTX group compared to the other three groups (P < 0.05); (3) AL3818 and PTX increased the expression of ICD-related molecules, including CRT, HMGB1, ATP, and HSP70, with the AL3818 + PTX group demonstrating the most significant effect (P < 0.05); and (4) AL3818 can induce early exposure of CRT on the membrane in the Cal27 cell line. Compared with the control group, the AL3818 + CCT020312 positive control group, and the AL3818 + ISRIB negative control group, the differences are statistically significant, while the total CRT remains roughly unchanged. The experimental results also indicate that after AL3818 acts on the Cal27 cell line for 24 h, there is an upregulation of p-perk and p-eIF2a expression along with the synchronous expression of CRT on the membrane.

CONCLUSION

AL3818 has the potential to induce ICD in the Cal27 TSCC cell line by modulating the levels of ICD-related molecules such as ATP, CRT, HSP70, and HMGB1. Moreover, the combination of AL3818 and PTX is more effective in inducing ICD in Cal27 cells compared to either agent alone. The process by which CRT is transferred from within the cell to the membrane during the induction of ICD in the Cal27 cell line by AL3818 may be related to the phosphorylation and activation of the PERK/elF2a signaling pathway.

Targeting B7-H3 enhances the efficacy of neoantigen-based cancer vaccine in combination with radiotherapy

The clinical response to immune checkpoint blockade (ICB) is limited in the majority of patients with colorectal cancer. These immune checkpoint proteins may not only inhibit T-cell-mediated antitumor immunity but also attenuate antigen presentation, including mutation-associated neoantigens. Here, we found that tumor B7-H3 levels may limit the therapeutic response to chemoradiotherapy in patients with locally-advanced rectal cancer. Knockdown of tumor B7-H3 significantly increased antigen presentation to increase T cell infiltration and killing ability, including neoantigen-specific T-cell response. Blockade of B7-H3 significantly augmented neoantigen-specific T cells response and remarkably enhanced the therapeutic efficacy of neoantigen-based cancer vaccines combined with radiotherapy, decreasing the risk of distant tumors in vivo. Taken together, these results demonstrated that targeting B7-H3 significantly enhanced the therapeutic efficacy of neoantigen cancer vaccines as well as radiotherapy by increasing the extent of neoantigen-specific T cells, even for PD-1/PD-L1 blockade-resistant colorectal cancers.

Metformin Inhibits Cell Motility and Proliferation of Triple-Negative Breast Cancer Cells by Blocking HMGB1/RAGE Signaling

High-mobility group box 1 (HMGB1) is a nuclear chromatin protein overexpressed in various cancers and linked to tumor progression. Outside the cell, HMGB1 binds to receptors such as the receptor for advanced glycation end products (RAGE), promoting metastasis. Targeting this signaling pathway may provide a new therapeutic strategy for aggressive cancers. Metformin, a well-established antidiabetic drug, directly interacts with HMGB1, inhibiting its pro-inflammatory functions. This study investigates metformin's effects on the HMGB1/RAGE signaling pathway in triple-negative breast cancer (TNBC) cells. Using wound-healing and colony formation assays, we demonstrate that metformin reduces HMGB1-induced cell migration and proliferation. Immunoblotting and immunofluorescence analyses reveal that metformin decreases RAGE stabilization on the cell membrane, disrupts NF-κB signaling, and reverses the epithelial-to-mesenchymal transition (EMT) by increasing E-cadherin, reducing vimentin, and stabilizing β-catenin at the cell membrane. Furthermore, metformin lowers HMGB1 and RAGE protein levels, disrupting the positive feedback loop that promotes cancer aggressiveness. These findings highlight metformin's potential as a therapeutic agent in TNBC by inhibiting HMGB1/RAGE-driven metastasis.

Tumor Necrosis Factor-α-Dependent Inflammation Upregulates High Mobility Group Box 1 To Induce Tumor Promotion and Anti-Programmed Cell Death Protein-1 Immunotherapy Resistance in Lung Adenocarcinoma

Tumor-associated chronic lung inflammation depends on tumor necrosis factor (TNF)-α to activate several cytokines as part of an inflammatory loop, which plays a critical role in tumor progression in lung adenocarcinoma. High mobility group box 1 (HMGB1) is a cytokine that mediates inflammation. Whether TNF-α-induced inflammation regulates HMGB1 to contribute to tumor progression and promotion in lung adenocarcinoma remains unclear. Thus, human samples and a urethane-induced inflammation-driven lung adenocarcinoma (IDLA) mouse model were used to explore the involvement of HMGB1 in tumorigenesis and tumor progression and efficacy of anti-programmed cell death protein (PD)-1 immunotherapy. High levels of HMGB1 were observed in human lung adenocarcinoma associated with poor overall survival in patients. HMGB1 upregulation was positively correlated with TNF-α-related inflammation and TIM-3+ infiltration. TNF-α upregulated intracellular and extracellular HMGB1 expression to contribute to tumor promotion in A549 cells in vitro. Using a urethane-induced IDLA mouse model, we found HMGB1 upregulation was associated with increased TIM-3+ T-cell infiltration. Blocking TNF-α-dependent inflammation downregulated HMGB1 expression and inhibited tumorigenesis in the IDLA model. Anti-PD-1 treatment alone did not inhibit tumor growth in the TNF-α-dependent IDLA, whereas anti-PD-1 combined with TNF-α blockade overcame anti-PD-1 immunotherapy resistance. Furthermore, anti-PD-1 combined with anti-HMGB1 also inhibited tumor growth in IDLA, suggesting that increased HMGB1 release by TNF-α contributes to the resistance of anti-PD-1 immunotherapy in IDLA. Thus, tumor-associated TNF-α-dependent inflammation upregulated intracellular and extracellular HMGB1 expression in an inflammatory loop, contributing to tumor promotion and anti-PD-1 immunotherapy resistance in lung adenocarcinoma.

The Role of Natural Products from Herbal Medicine in TLR4 Signaling for Colorectal Cancer Treatment

The toll-like receptor 4 (TLR4) signaling pathway constitutes an intricate network of protein interactions primarily involved in inflammation and cancer. This pathway triggers intracellular signaling cascades, modulating transcription factors that regulate gene expression related to immunity and malignancy. Previous studies showed that colon cancer patients with low TLR4 expression exhibit extended survival times and the TLR4 signaling pathway holds a significant role in CRC pathogenesis. In recent years, traditional Chinese medicines (TCMs) have garnered substantial attention as an alternative therapeutic modality for CRC, primarily due to their multifaceted composition and ability to target multiple pathways. Emerging evidence indicates that specific TCM products, such as andrographolide, rosmarinic acid, baicalin, etc., have the potential to impede CRC development through the TLR4 signaling pathway. Here, we review the role and biochemical processes of the TLR4 signaling pathway in CRC, and natural products from TCMs affecting the TLR4 pathway. This review sheds light on potential treatment strategies utilizing natural TLR4 inhibitors for CRC, which contributes to the advancement of research and accelerates their clinical integration into CRC treatment.

Colorectal cancer-specific IFNβ delivery overcomes dysfunctional dsRNA-mediated type I interferon signaling to increase the abscopal effect of radiotherapy

BACKGROUND

Cancer-intrinsic type I interferon (IFN-I) production triggered by radiotherapy (RT) is mainly dependent on cytosolic double-stranded DNA (dsDNA)-mediated cGAS/STING signaling and increases cancer immunogenicity and enhances the antitumor immune response to increase therapeutic efficacy. However, cGAS/STING deficiency in colorectal cancer (CRC) may suppress the RT-induced antitumor immunity. Therefore, we aimed to evaluate the importance of the dsRNA-mediated antitumor immune response induced by RT in patients with CRC.

METHODS

Cytosolic dsRNA level and its sensors were evaluated via cell-based assays (co-culture assay, confocal microscopy, pharmacological inhibition and immunofluorescent staining) and in vivo experiments. Biopsies and surgical tissues from patients with CRC who received preoperative chemoradiotherapy (neoCRT) were collected for multiplex cytokine assays, immunohistochemical analysis and SNP genotyping. We also generated a cancer-specific adenovirus-associated virus (AAV)-IFNβ1 construct to evaluate its therapeutic efficacy in combination with RT, and the immune profiles were analyzed by flow cytometry and RNA-seq.

RESULTS

Our studies revealed that RT stimulates the autonomous release of dsRNA from cancer cells to activate TLR3-mediated IFN-I signatures to facilitate antitumor immune responses. Patients harboring a dysfunctional TLR3 variant had reduced serum levels of IFN-I-related cytokines and intratumoral CD8+ immune cells and shorter disease-free survival following neoCRT treatment. The engineered cancer-targeted construct AAV-IFNβ1 significantly improved the response to RT, leading to systematic eradication of distant tumors and prolonged survival in defective TLR3 preclinical models.

CONCLUSION

Our results support that increasing cancer-intrinsic IFNβ1 expression is an immunotherapeutic strategy that enhances the RT-induced antitumor immune response in locally patients with advanced CRC with dysfunctional TLR3.

Clinicopathological Significance and Prognostic Role of High Mobility Group Box 1 (HMGB1), Toll-Like Receptor (TLR) 2 and TLR4 in Breast Cancer

High-mobility group box 1 (HMGB1) functions as damage-associated molecular pattern (DAMPs), released into extracellular space during cellular stress. Extracellular HMGB1 act as signal molecules through Toll-like receptor (TLR) 2 or TLR4, exerting diverse functions in both normal cells and malignant cells including breast cancer. However, their comprehensive examination in breast cancer tissues is lacking. Thus, we immunolocalized them in 112 breast cancer tissues, correlating their immunoreactivity with clinicopathological parameters and clinical outcomes to clarify their significance in breast cancer. We demonstrated that nuclear HMGB1 immunoreactivity was correlated with tumor progression and longer disease-free survival. In contrast, TLR2 immunoreactivity was correlated with increased cell proliferation and shorter disease-free survival, dependent on cytoplasmic HMGB1 immunoreactivity. Additionally, TLR4 immunoreactivity correlated with chemoresistance, regardless of cytoplasmic HMGB1 immunoreactivity. It was therefore considered that TLR2 collaboratively contributed to breast cancer progression with HMGB1-DAMPs to become a worse prognostic factor. Meanwhile, TLR4 served as a worse prognostic factor associated with chemoresistance, irrespective of HMGB1.

Activation of STING by the novel liposomal TLC388 enhances the therapeutic response to anti-PD-1 antibodies in combination with radiotherapy

Current immune checkpoint inhibiters (ICIs) have contrasting clinical results in poorly immunogenic cancers such as microsatellite-stable colorectal cancer (MSS-CRC). Therefore, understanding and developing the combinational therapeutics for ICI-unresponsive cancers is critical. Here, we demonstrated that the novel topoisomerase I inhibitor TLC388 can reshape the tumor immune landscape, corroborating their antitumor effects combined with radiotherapy as well as immunotherapy. We found that TLC388 significantly triggered cytosolic single-stranded DNA (ssDNA) accumulation for STING activation, leading to type I interferons (IFN-Is) production for increased cancer immunogenicity to enhance antitumor immunity. TLC388-treated tumors were infiltrated by a vast number of dendritic cells, immune cells, and costimulatory molecules, contributing to the favorable antitumor immune response within the tumor microenvironment. The infiltration of cytotoxic T and NK cells were more profoundly existed within tumors in combination with radiotherapy and ICIs, leading to superior therapeutic efficacy in poorly immunogenic MSS-CRC. Taken together, these results showed that the novel topoisomerase I inhibitor TLC388 increased cancer immunogenicity by ssDNA/STING-mediated IFN-I production, enhancing antitumor immunity for better therapeutic efficacy in combination with radiotherapy and ICIs for poorly immunogenic cancer.

TNFα modulates PANX1 activation to promote ATP release and enhance P2RX7-mediated antitumor immune responses after chemotherapy in colorectal cancer

ATP and its receptor P2RX7 exert a pivotal effect on antitumor immunity during chemotherapy-induced immunogenic cell death (ICD). Here, we demonstrated that TNFα-mediated PANX1 cleavage was essential for ATP release in response to chemotherapy in colorectal cancer (CRC). TNFα promoted PANX1 cleavage via a caspase 8/3-dependent pathway to enhance cancer cell immunogenicity, leading to dendritic cell maturation and T-cell activation. Blockade of the ATP receptor P2RX7 by the systemic administration of small molecules significantly attenuated the therapeutic efficacy of chemotherapy and decreased the infiltration of immune cells. In contrast, administration of an ATP mimic markedly increased the therapeutic efficacy of chemotherapy and enhanced the infiltration of immune cells in vivo. High PANX1 expression was positively correlated with the recruitment of DCs and T cells within the tumor microenvironment and was associated with favorable survival outcomes in CRC patients who received adjuvant chemotherapy. Furthermore, a loss-of-function P2RX7 mutation was associated with reduced infiltration of CD8+ immune cells and poor survival outcomes in patients. Taken together, these results reveal that TNFα-mediated PANX1 cleavage promotes ATP-P2RX7 signaling and is a key determinant of chemotherapy-induced antitumor immunity.

Dysfunctional TLR1 reduces the therapeutic efficacy of chemotherapy by attenuating HMGB1-mediated antitumor immunity in locally advanced colorectal cancer

Regional lymph node metastasis is an important predictor for survival outcome and an indicator for postoperative adjuvant chemotherapy in patients with colorectal cancer. Even with advances in adjuvant chemotherapeutic regimens, 5-year distant metastasis and survival rates are still unsatisfactory. Here, we evaluate the clinical significance of polymorphisms in receptors for HMGB1, which is the hallmark of chemotherapy-induced immunogenic cell death, in patients with stage II-III colon carcinoma (COAD). We found that high cytosolic HMGB1 is elicited in stage III COAD patients who received adjuvant chemotherapy. Patients with the TLR1-N248S polymorphism (rs4833095), which causes loss-of-function in HMGB1-mediated TLR1-TLR2 signaling, may influence the therapeutic efficacy of adjuvant chemotherapy, leading to a high risk of distant metastasis within 5 years [HR = 1.694, 95% CI = 1.063-2.698, p = 0.027], suggesting that TLR1-N248S is an independent prognostic factor for locally advanced colon carcinoma patients. We found that defective TLR1 impaired TLR1/2 signaling during dendritic cell (DC) maturation for the antitumor immune response under immunogenic chemotherapy oxaliplatin (OXP) treatment. Defective TLR1 on DCs impaired their maturation ability by HMGB1 and reduced the secretion of IFNγ from T cells to eradicate tumor cells in vitro. Moreover, systemic inhibition of TLR1/2 dramatically reduced the tumor-infiltrating immune cells by OXP treatment, leading to poor therapeutic response to OXP. In contrast, administration of a TLR1/2 agonist synergistically increased the benefit of OXP treatment and triggered a high density of tumor-infiltrating immune cells. We also observed that fewer tumor-infiltrating cytotoxic T lymphocytes were located within the tumor microenvironment in patients bearing the TLR1-N248S polymorphism. Overall, our results suggest that dysfunctional TLR1 may reduce the therapeutic response to adjuvant chemotherapy by impairing HMGB1-mediated DC maturation and attenuating the antitumor immune response in locally advanced colon carcinoma patients.

Implications of Rectal Cancer Radiotherapy on the Immune Microenvironment: Allies and Foes to Therapy Resistance and Patients' Outcome

Aside from surgical resection, locally advanced rectal cancer is regularly treated with neoadjuvant chemoradiotherapy. Since the concept of cancer treatment has shifted from only focusing on tumor cells as drivers of disease progression towards a broader understanding including the dynamic tumor microenvironment (TME), the impact of radiotherapy on the TME and specifically the tumor immune microenvironment (TIME) is increasingly recognized. Both promoting as well as suppressing effects on anti-tumor immunity have been reported in response to rectal cancer (chemo-)radiotherapy and various targets for combination therapies are under investigation. A literature review was conducted searching the PubMed database for evidence regarding the pleiotropic effects of (chemo-)radiotherapy on the rectal cancer TIME, including alterations in cytokine levels, immune cell populations and activity as well as changes in immune checkpoint proteins. Radiotherapy can induce immune-stimulating and -suppressive alterations, potentially mediating radioresistance. The response is influenced by treatment modalities, including the dosage administered and the highly individual intrinsic pre-treatment immune status. Directly addressing the main immune cells of the TME, this review aims to highlight therapeutical implications since efficient rectal cancer treatment relies on personalized strategies combining conventional therapies with immune-modulating approaches, such as immune checkpoint inhibitors.

The Redox Protein High-Mobility Group Box 1 in Cell Death and Cancer

Significance: As a redox-sensitive protein, high-mobility group box 1 (HMGB1) is implicated in regulating stress responses to oxidative damage and cell death, which are closely related to the pathology of inflammatory diseases, including cancer. Recent Advances: HMGB1 is a nonhistone nuclear protein that acts as a deoxyribonucleic acid chaperone to control chromosomal structure and function. HMGB1 can also be released into the extracellular space and function as a damage-associated molecular pattern protein during cell death, including during apoptosis, necrosis, necroptosis, pyroptosis, ferroptosis, alkaliptosis, and cuproptosis. Once released, HMGB1 binds to membrane receptors to shape immune and metabolic responses. In addition to subcellular localization, the function and activity of HMGB1 also depend on its redox state and protein posttranslational modifications. Abnormal HMGB1 plays a dual role in tumorigenesis and anticancer therapy (e.g., chemotherapy, radiation therapy, and immunotherapy) depending on the tumor types and stages. Critical Issues: A comprehensive understanding of the role of HMGB1 in cellular redox homeostasis is important for deciphering normal cellular functions and pathological manifestations. In this review, we discuss compartmental-defined roles of HMGB1 in regulating cell death and cancer. Understanding these advances may help us develop potential HMGB1-targeting drugs or approaches to treat oxidative stress-related diseases or pathological conditions. Future Directions: Further studies are required to dissect the mechanism by which HMGB1 maintains redox homeostasis under different stress conditions. A multidisciplinary effort is also required to evaluate the potential applications of precisely targeting the HMGB1 pathway in human health and disease. Antioxid. Redox Signal. 39, 569-590.

IMMUNOREACT 0: Biopsy-based immune biomarkers as predictors of response to neoadjuvant therapy for rectal cancer-A systematic review and meta-analysis

BACKGROUND

The main therapy for rectal cancer patients is neoadjuvant therapy (NT) followed by surgery. Immune biomarkers are emerging as potential predictors of the response to NT. We performed a meta-analysis to estimate their predictive significance.

METHODS

A systematic literature search of PubMed, Ovid MEDLINE and EMBASE databases was performed to identify eligible studies. Studies on patients with rectal cancer undergoing NT in which the predictive significance of at least one of the immunological markers of interest was assessed by immunohistochemistry (IHC) in pretreatment biopsies were included.

RESULTS

Seventeen studies reporting sufficient data met the inclusion criteria for meta-analysis. High levels of total CD3+, CD4+ and CD8+ tumor infiltrating lymphocytes (TILs), as well as stromal and intraepithelial CD8+ compartments, significantly predicted good pathological response to NT. Moreover, high levels of total (tumoral and immune cell expression) PD-L1 resulted associated to a good pathological response. On the contrary, high levels of intraepithelial CD4+ TILs were correlated with poor pathological response. FoxP3+ TILs, tumoral PD-L1 and CTLA-4 were not correlated to the treatment response.

CONCLUSION

This meta-analysis indicated that high-density TILs might be predictive biomarkers of pathological response in patients that underwent NT for rectal cancer.

Implications of receptor for advanced glycation end products for progression from obesity to diabetes and from diabetes to cancer

Obesity and type 2 diabetes mellitus (T2DM) are chronic pathologies with a high incidence worldwide. They share some pathological mechanisms, including hyperinsulinemia, the production and release of hormones, and hyperglycemia. The above, over time, affects other systems of the human body by causing tissue hypoxia, low-grade inflammation, and oxidative stress, which lay the pathophysiological groundwork for cancer. The leading causes of death globally are T2DM and cancer. Other main alterations of this pathological triad include the accumulation of advanced glycation end products and the release of endogenous alarmins due to cell death (i.e., damage-associated molecular patterns) such as the intracellular proteins high-mobility group box protein 1 and protein S100 that bind to the receptor for advanced glycation products (RAGE) - a multiligand receptor involved in inflammatory and metabolic and neoplastic processes. This review analyzes the latest advanced reports on the role of RAGE in the development of obesity, T2DM, and cancer, with an aim to understand the intracellular signaling mechanisms linked with cancer initiation. This review also explores inflammation, oxidative stress, hypoxia, cellular senescence, RAGE ligands, tumor microenvironment changes, and the “cancer hallmarks” of the leading tumors associated with T2DM. The assimilation of this information could aid in the development of diagnostic and therapeutic approaches to lower the morbidity and mortality associated with these diseases.

Targeting CD73 increases therapeutic response to immunogenic chemotherapy by promoting dendritic cell maturation

The CD39-CD73-adenosinergic pathway converts adenosine triphosphate (ATP) to adenosine for inhibiting anti-tumor immune responses. Therefore, targeting CD73 to reinvigorate anti-tumor immunity is considered the novel cancer immunotherapy to eradicate tumor cells. To fully understand the critical role of CD39/CD73 in colon adenocarcinoma (COAD), this study aims to comprehensive investigate the prognostic significance of CD39 and CD73 in stage I-IV COAD. Our data demonstrated that CD73 staining strongly marked malignant epithelial cells and CD39 was highly expressed in stromal cells. Attractively, tumor CD73 expression was significantly associated with tumor stage and the risk of distant metastasis, which suggested CD73 was as an independent factor for colon adenocarcinoma patients in univariate COX analysis [HR = 1.465, 95%CI = 1.084-1.978, p = 0.013]; however, high stromal CD39 in COAD patients was more likely to have favorable survival outcome [HR = 1.458, p = 1.103-1.927, p = 0.008]. Notably, high CD73 expression in COAD patients showed poor response to adjuvant chemotherapy and high risk of distant metastasis. High CD73 expression was inversely associated with less infiltration of CD45+ and CD8+ immune cells. However, administration with anti-CD73 antibodies significantly increased the response to oxaliplatin (OXP). Blockade of CD73 signaling synergistically enhanced OXP-induced ATP release, which is a marker of immunogenic cell death (ICD), promotes dendritic cell maturation and immune cell infiltration. Moreover, the risk of colorectal cancer lung metastasis was also decreased. Taken together, the present study revealed tumor CD73 expression inhibited the recruitment of immune cells and correlated with a poor prognosis in COAD patients, especially patients received adjuvant chemotherapy. Targeting CD73 to markedly increased the therapeutic response to chemotherapy and inhibited lung metastasis. Therefore, tumor CD73 may be an independent prognostic factor as well as the potential of therapeutic target for immunotherapy to benefit colon adenocarcinoma patients.

A Novel Engineered AAV-Based Neoantigen Vaccine in Combination with Radiotherapy Eradicates Tumors

The potency of tumor-specific antigen (TSA) vaccines, such as neoantigen (neoAg)-based cancer vaccines, can be compromised by host immune checkpoint inhibitory mechanisms, such as programmed cell death protein 1 (PD-1)/programmed death ligand 1 (PD-L1), that attenuate neoAg presentation on dendritic cells (DC) and hinder T cell-mediated cytotoxicity. To overcome PD-1/PD-L1 inhibition in DCs, we developed a novel adeno-associated virus (meAAV) neoAg vaccine, modified with TLR9 inhibitory fragments, PD-1 trap, and PD-L1 miRNA, which extend the persistence of meAAV and activate neoAg-specific T-cell responses in immune-competent colorectal and breast cancer murine models. Moreover, we found that in combination with radiotherapy, the meAAV-based neoAg cancer vaccine not only elicited higher antigen presentation ability, but also maintained neoAg-specific cytotoxic T lymphocyte (CTL) responses. These functional PD-1 traps and PD-L1 miRNAs overcome host PD-1/PD-L1 inhibitory mechanisms and boost the therapeutic efficacy of radiotherapy. More importantly, combined radiotherapy and meAAV neoAg cancer vaccines significantly enhanced neoAg-specific CTL responses, increased CTL infiltration in tumor microenvironment, and decreased tumor-associated immunosuppression. This process led to the complete elimination of colorectal cancer and delayed tumor growth of breast cancer in tumor-bearing mice. Taken together, our results demonstrated a novel strategy that combines neoAg cancer vaccine and radiotherapy to increase the therapeutic efficacy against colorectal and breast cancers.

The implications from the interplay of neoadjuvant chemoradiotherapy and the immune microenvironment in rectal cancer

Neoadjuvant chemoradiotherapy (nCRT) is recommended for the treatment of locally advanced rectal cancer. Even though the combination of nCRT and immune checkpoint inhibitors (ICIs) has received much attention, the specific combination modes and dose fractions in radiotherapy (RT) are still indistinct. This review focuses on the immunological mechanism involved in nCRT, the clinical efficacy, the immunological effect of different combined strategies, concurrent or sequential nCRT plus ICIs, long-course RT and short-course RT. This review discusses the impact of nCRT on tumor immunity and summarizes the availability of different dose fractions in RT and distinct combined strategies, aiming at providing clues for optimal neoadjuvant therapy options that maximize efficacy and minimize side effects.

The Features of Checkpoint Receptor—Ligand Interaction in Cancer and the Therapeutic Effectiveness of Their Inhibition

To date, certain problems have been identified in cancer immunotherapy using the inhibition of immune checkpoints (ICs). Despite the excellent effect of cancer therapy in some cases when blocking the PD-L1 (programmed death-ligand 1) ligand and the immune cell receptors PD-1 (programmed cell death protein 1) and CTLA4 (cytotoxic T-lymphocyte-associated protein 4) with antibodies, the proportion of patients responding to such therapy is still far from desirable. This situation has stimulated the exploration of additional receptors and ligands as targets for immunotherapy. In our article, based on the analysis of the available data, the TIM-3 (T-cell immunoglobulin and mucin domain-3), LAG-3 (lymphocyte-activation gene 3), TIGIT (T-cell immunoreceptor with Ig and immunoreceptor tyrosine-based inhibitory motif (ITIM) domains), VISTA (V-domain Ig suppressor of T-cell activation), and BTLA (B- and T-lymphocyte attenuator) receptors and their ligands are comprehensively considered. Data on the relationship between receptor expression and the clinical characteristics of tumors are presented and are analyzed together with the results of preclinical and clinical studies on the therapeutic efficacy of their blocking. Such a comprehensive analysis makes it possible to assess the prospects of receptors of this series as targets for anticancer therapy. The expression of the LAG-3 receptor shows the most unambiguous relationship with the clinical characteristics of cancer. Its inhibition is the most effective of the analyzed series in terms of the antitumor response. The expression of TIGIT and BTLA correlates well with clinical characteristics and demonstrates antitumor efficacy in preclinical and clinical studies, which indicates their high promise as targets for anticancer therapy. At the same time, the relationship of VISTA and TIM-3 expression with the clinical characteristics of the tumor is contradictory, and the results on the antitumor effectiveness of their inhibition are inconsistent.

An Overview on Immunogenic Cell Death in Cancer Biology and Therapy

Immunogenic cell death (ICD) is a modality of regulated cell death that is sufficient to promote an adaptive immune response against antigens of the dying cell in an immunocompetent host. An important characteristic of ICD is the release and exposure of damage-associated molecular patterns, which are potent endogenous immune adjuvants. As the induction of ICD can be achieved with conventional cytotoxic agents, it represents a potential approach for the immunotherapy of cancer. Here, different aspects of ICD in cancer biology and treatment are reviewed.

Contribution of TLR4 to colorectal tumor microenvironment, etiology and prognosis

PURPOSE

Toll-like receptor 4 (TLR4) is increasingly recognized for its ability to govern the etiology and prognostic outcomes of colorectal cancer (CRC) due to its profound immunomodulatory capacity. Despite widespread interest in TLR4 and CRC, no clear analysis of current literature and data exists. Therefore, translational advances have failed to move beyond conceptual ideas and suggestions.

METHODS

We aimed to determine the relationship between TLR4 and CRC through a systematic review and analysis of published literature and datasets. Data were extracted from nine studies that reported survival, CRC staging and tumor progression data in relation to TLR4 expression. Primary and metastatic tumor samples with associated clinical data were identified through the Cancer Genome Atlas (TCGA) database.

RESULTS

Systematic review identified heterogeneous relationships between TLR4 and CRC traits, with no clear theme evident across studies. A total of 448 datasets were identified through the TCGA database. Analysis of TCGA datasets revealed TLR4 mRNA expression is decreased in advanced CRC stages (P < 0.05 for normal vs Stage II, Stage III and Stage IV). Stage-dependent impact of TLR4 expression on survival outcomes were also found, with high TLR4 expression associated with poorer prognosis (stage I vs III (HR = 4.2, P = 0.008) and stage I vs IV (HR = 11.3, P < 0.001)).

CONCLUSION

While TLR4 mRNA expression aligned with CRC staging, it appeared to heterogeneously regulate survival outcomes depending on the stage of disease. This underscores the complex relationship between TLR4 and CRC, with unique impacts dependent on disease stage.

Engineered sTRAIL-armed MSCs overcome STING deficiency to enhance the therapeutic efficacy of radiotherapy for immune checkpoint blockade

Radiotherapy (RT) mainly elicits antitumor immunity via the cGAS/STING axis for type I interferon (IFN) production. However, dysregulation of cGAS/STING constrains radiotherapy-induced antitumor immunity and type I IFN-dependent cell death and is associated with shorter survival of patients with colorectal cancer (CRC). Due to their tumor tropism, mesenchymal stem cells (MSCs) have shown the potential to deliver therapeutic genes for cancer therapy. Here, we showed that MSCs enhance the sensitivity to RT by inducing TRAIL-dependent cell death and remodel the tumor microenvironment by recruiting CD8+ immune cells to upregulate PD-L1 in the tumor. By engineering MSCs to express CRC-specific soluble TRAIL via adenovirus-associated virus 2 (AAV2), we found that the therapeutic activity of MSC-sTRAIL was superior to that of MSCs alone when combined with RT. Combined treatment with MSC-sTRAIL and RT significantly reduced cell viability and increased apoptosis by inducing TRAIL-dependent cell death in STING-deficient colorectal cancer cells. MSC-sTRAIL directly triggered TRAIL-dependent cell death to overcome the deficiency of the cGAS/STING axis. Moreover, these combination treatments of MSC-sTRAIL and RT significantly remodeled the tumor microenvironment, which was more suitable for anti-PD-L1 immunotherapy. Taken together, this therapeutic strategy represents a novel targeted treatment option for patients with colorectal cancer, especially cGAS/STING-deficient patients.

High Mobility Group Protein B1 Decreases Surface Localization of PD-1 to Augment T-cell Activation

High-mobility group protein B1 (HMGB1) is a danger signaling molecule that has been found to trigger an effective antitumor immune response. However, the mechanisms underlying its antitumor effects are not fully understood. Here, we found that HMGB1 release induced by chemotherapy in patients with non-small cell lung cancer was negatively correlated with PD-1 expression on CD8+ T cells. In vitro analysis indicated that treatment with HMGB1 led to a significant decrease in the level of expression of PD-1 on CD8+ T cells. Further analysis demonstrated that HMGB1 reduced PD-1 expression by inducing dynamin-mediated internalization of the protein, leading to early endocytosis in the cytoplasm, and subsequently degradation in the lysosomes. In a xenograft model, HER2-targeted chimeric antigen receptor (CAR) T cells had enhanced function in the presence of HMGB1. These data identify a role for HMGB1 as a negative regulator of PD-1 signaling in lung cancer and the observed antitumor effect of HMGB1 on CAR T cells may provide a theoretical foundation for a new immunotherapy combination.

Dual inhibition of TGFβ signaling and CSF1/CSF1R reprograms tumor-infiltrating macrophages and improves response to chemotherapy via suppressing PD-L1

TGFβ contributes to chemoresistance in advanced colorectal cancer (CRC) via diverse immune-microenvironment mechanisms. Here, we found that cancer cell autonomous TGFβ directly triggered tumor programmed cell death 1 ligand 1 (PD-L1) upregulation, resulting in resistance to chemotherapy. Inhibition of tumor PD-L1 expression sensitized cancer cells to chemotherapy, reduced lung metastasis and increased the influx of CD8⁺ T cells. However, chemorefractory cancer cell-derived CSF1 recruited TAMs for TGFβ-mediated PD-L1 upregulation via a vicious cycle. High infiltration of macrophages was clinically correlated with the status of tumor PD-L1 after chemotherapy treatment in CRC patients. We found that depletion of immunosuppressive CSF1R⁺ TAM infiltration and blockade of the TGFβ receptor resulted in an increased influx of cytotoxic CD8⁺ T and effector memory CD8⁺ cells, a reduction in regulatory T cells, and a synergistic inhibition of tumor growth when combined with chemotherapy. These findings show that CSF1R⁺ TAMs and TGFβ are the dominant components that regulate PD-L1 expression within the immunosuppressive tumor microenvironment, providing a therapeutic strategy for advanced CRC patients.

Immunogenic Cell Death, DAMPs and Prothymosin α as a Putative Anticancer Immune Response Biomarker

The new and increasingly studied concept of immunogenic cell death (ICD) revealed a previously unknown perspective of the various regulated cell death (RCD) modalities, elucidating their immunogenic properties and rendering obsolete the notion that immune stimulation is solely the outcome of necrosis. A distinct characteristic of ICD is the release of danger-associated molecular patterns (DAMPs) by dying and/or dead cells. Thus, several members of the DAMP family, such as the well-characterized heat shock proteins (HSPs) HSP70 and HSP90, the high-mobility group box 1 protein and calreticulin, and the thymic polypeptide prothymosin α (proTα) and its immunoreactive fragment proTα(100–109), are being studied as potential diagnostic tools and/or possible therapeutic agents. Here, we present the basic aspects and mechanisms of both ICD and other immunogenic RCD forms; denote the role of DAMPs in ICD; and further exploit the relevance of human proTα and proTα(100–109) in ICD, highlighting their possible clinical applications. Furthermore, we present the preliminary results of our in vitro studies, which show a direct correlation between the concentration of proTα/proTα(100–109) and the levels of cancer cell apoptosis, induced by anticancer agents and γ-radiation.

Programmed Cell Death Tunes Tumor Immunity

The demise of cells in various ways enables the body to clear unwanted cells. Studies over the years revealed distinctive molecular mechanisms and functional consequences of several key cell death pathways. Currently, the most intensively investigated programmed cell death (PCD) includes apoptosis, necroptosis, pyroptosis, ferroptosis, PANoptosis, and autophagy, which has been discovered to play crucial roles in modulating the immunosuppressive tumor microenvironment (TME) and determining clinical outcomes of the cancer therapeutic approaches. PCD can play dual roles, either pro-tumor or anti-tumor, partly depending on the intracellular contents released during the process. PCD also regulates the enrichment of effector or regulatory immune cells, thus participating in fine-tuning the anti-tumor immunity in the TME. In this review, we focused primarily on apoptosis, necroptosis, pyroptosis, ferroptosis, PANoptosis, and autophagy, discussed the released molecular messengers participating in regulating their intricate crosstalk with the immune response in the TME, and explored the immunological consequence of PCD and its implications in future cancer therapy developments.

Debating Pros and Cons of Total Neoadjuvant Therapy in Rectal Cancer

Simple Summary

Rectal cancers represent one third of all colorectal tumours. Patients diagnosed with localised colon cancer undergo surgery upfront, likely followed by adjuvant chemotherapy. Those diagnosed with localised rectal cancer, however, frequently benefit from neoadjuvant treatments with either radiotherapy or chemoradiotherapy before undergoing surgery. On the other hand, the benefit of adjuvant chemotherapy in this setting is more controversial. The main challenges in treating patients affected by rectal cancer encompass: decreasing the risks of local relapse and distant metastases, preserving the sphincter and minimising treatment-associated functional sequelae, and improving overall survival. Some of these fuelled the concept of total neoadjuvant therapy, namely giving all available treatments including radiotherapy and systemic chemotherapy before surgery. Here, we critically review the pros and cons of such a treatment strategy, but also discuss the biological rational to support neoadjuvant treatment intensification.

Abstract

Recently, two large, randomised phase III clinical trials of total neoadjuvant therapy (TNT) in locally advanced rectal cancer were published (RAPIDO and PRODIGE 23). These two trials compared short-course radiotherapy (SCRT) followed by chemotherapy with standard chemoradiotherapy (CRT) and chemotherapy followed by CRT with standard CRT, respectively. They showed improvement in some of the outcomes such as distant recurrence and pathological complete response (pCR). No improvement, however, was observed in local disease control or the de-escalation of surgical procedures. Although it seems lawful to integrate TNT within the treatment algorithm of localised stage II and III rectal cancer, many questions remain unanswered, including which are the optimal criteria to identify patients who are most likely to benefit from this intensive treatment. Instead of providing a sterile summary of trial results, we put these in perspective in a pros and cons manner. Moreover, we discuss some biological aspects of rectal cancer, which may provide some insights into the current decision-making process, and represent the basis for the future development of alternative, more effective treatment strategies.

Immunogenic Cell Death Induction by Ionizing Radiation

Immunogenic cell death (ICD) is a form of regulated cell death (RCD) induced by various stresses and produces antitumor immunity via damage-associated molecular patterns (DAMPs) release or exposure, mainly including high mobility group box 1 (HMGB1), calreticulin (CRT), adenosine triphosphate (ATP), and heat shock proteins (HSPs). Emerging evidence has suggested that ionizing radiation (IR) can induce ICD, and the dose, type, and fractionation of irradiation influence the induction of ICD. At present, IR-induced ICD is mainly verified in vitro in mice and there is few clinical evidence about it. To boost the induction of ICD by IR, some strategies have shown synergy with IR to enhance antitumor immune response, such as hyperthermia, nanoparticles, and chemotherapy. In this review, we focus on the molecular mechanisms of ICD, ICD-promoting factors associated with irradiation, the clinical evidence of ICD, and immunogenic forms of cell death. Finally, we summarize various methods of improving ICD induced by IR.

ATAD3A stabilizes GRP78 to suppress ER stress for acquired chemoresistance in colorectal cancer

AAA domain containing 3A (ATAD3A) is a nucleus-encoded mitochondrial protein with vital function in communication between endoplasmic reticulum (ER) and mitochondria which is participated in cancer metastasis. Here we show that elevated ATAD3A expression is clinically associated with poor 5-year disease-free survival in patients with colorectal cancer (CRC), especially high-risk CRC patients who received adjuvant chemotherapy. Our results indicated ATAD3A is significantly upregulated to reduce chemotherapy-induced cancer cell death. We found that knockdown of ATAD3A leads to dysregulation in protein processing for inducing ER stress by RNA sequencing (RNA-seq). In response to chemotherapy-induced ER stress, ATAD3A interacts with elevated GRP78 protein to assist protein folding and alleviate ER stress for cancer cell survival. This reduction of ER stress leads to reduce the surface exposure of calreticulin, which is the initiator of immunogenic cell death and antitumor immunity. However, silencing of ATAD3A enhances cell death, triggers the feasibility of chemotherapy-induced ER stress for antitumor immunity, increases infiltration of T lymphocytes and delays tumor regrowth in vitro and in vivo. Clinically, CRC patients with less ATAD3A have high density of CD45+ intratumoral infiltrating lymphocytes (TILs) and memory CD45RO+ TILs. Taken together, our results suggest that pharmacologic targeting to ATAD3A might be a potential therapeutic strategy to enhance antitumor immunity for CRC patients who received adjuvant chemotherapy.

Development and Validation of a Nomogram and a Comprehensive Prognostic Analysis of an LncRNA-Associated Competitive Endogenous RNA Network Based on Immune-Related Genes for Locally Advanced Rectal Cancer With Neoadjuvant Therapy

Colorectal cancer (CRC) is a common digestive tract tumor worldwide. In recent years, neoadjuvant chemoradiotherapy (CRT) has been the most comprehensive treatment for locally advanced rectal cancer (LARC). In this study, we explored immune infiltration in rectal cancer (RC) and identified immune-related differentially expressed genes (IRDEGs). Then, we identified response markers in datasets in GEO databases by principal component analysis (PCA). We also utilized three GEO datasets to identify the up- and downregulated response-related genes simultaneously and then identified genes shared between the PCA markers and three GEO datasets. Based on the hub IRDEGs, we identified target mRNAs and constructed a ceRNA network. Based on the ceRNA network, we explored prognostic biomarkers to develop a prognostic model for RC through Cox regression. We utilized the specimen to validate the expression of the two biomarkers. We also utilized LASSO regression to screen hub IRDEGs and built a nomogram to predict the response of LARC patients to CRT. All of the results show that the nomogram and prognostic model offer good prognostic value and that the ceRNA network can effectively highlight the regulatory relationship. hsa-mir-107 and WDFY3-AS2 may be prognostic biomarkers for RC.

Tumor Microenvironment: Key Players in Triple Negative Breast Cancer Immunomodulation

Simple Summary

The tumor microenvironment (TME) is a complicated network composed of various cells, signaling molecules, and extra cellular matrix. TME plays a crucial role in triple negative breast cancer (TNBC) immunomodulation and tumor progression, paradoxically, acting as an immunosuppressive as well as immunoreactive factor. Research regarding tumor immune microenvironment has contributed to a better understanding of TNBC subtype classification. Shall we treat patients precisely according to specific subtype classification? Moving beyond traditional chemotherapy, multiple clinical trials have recently implied the potential benefits of immunotherapy combined with chemotherapy. In this review, we aimed to elucidate the paradoxical role of TME in TNBC immunomodulation, summarize the subtype classification methods for TNBC, and explore the synergistic mechanism of chemotherapy plus immunotherapy. Our study may provide a new direction for the development of combined treatment strategies for TNBC.

Abstract

Triple negative breast cancer (TNBC) is a heterogeneous disease and is highly related to immunomodulation. As we know, the most effective approach to treat TNBC so far is still chemotherapy. Chemotherapy can induce immunogenic cell death, release of damage-associated molecular patterns (DAMPs), and tumor microenvironment (TME) remodeling; therefore, it will be interesting to investigate the relationship between chemotherapy-induced TME changes and TNBC immunomodulation. In this review, we focus on the immunosuppressive and immunoreactive role of TME in TNBC immunomodulation and the contribution of TME constituents to TNBC subtype classification. Further, we also discuss the role of chemotherapy-induced TME remodeling in modulating TNBC immune response and tumor progression with emphasis on DAMPs-associated molecules including high mobility group box1 (HMGB1), exosomes, and sphingosine-1-phosphate receptor 1 (S1PR1), which may provide us with new clues to explore effective combined treatment options for TNBC.

Cross-talks in colon cancer between RAGE/AGEs axis and inflammation/immunotherapy

The tumour microenvironment is the result of the activity of many types of cells in various metabolic states, whose metabolites are shared between cells. This cellular complexity results in an availability profile of nutrients and reactive metabolites such as advanced glycation end products (AGE). The tumour microenvironment is not favourable to immune cells due to hypoxia and for the existence of significant competition between various types of cells for a limited nutrient pool. However, it is now known that cancer cells can influence the host's immune reaction through the expression and secretion of numerous molecules. The microenvironment can therefore present itself in different patterns that contribute to shaping immune surveillance. Colorectal cancer (CRC) is one of the most important causes of death in cancer patients. Recently, immunotherapy has begun to give encouraging results in some groups of patients suffering from this neoplasm. The analysis of literature data shows that the RAGE (Receptor for advanced glycation end products) and its numerous ligands contribute to connect the energy metabolic pathway, which appears prevalently disconnected by mitochondrial running, with the immune reaction, conditioned by local microbiota and influencing tumour growth. Understanding how metabolism in cancer and immune cells shapes response and resistance to therapy, will provide novel potential strategies to increase both the number of tumour types treated by immunotherapy and the rate of immunotherapy response. The analysis of literature data shows that an immunotherapy approach based on the knowledge of RAGE and its ligands is not only possible, but also desirable in the treatment of CRC.

Therapy-Induced Tumor Cell Death: Friend or Foe of Immunotherapy?

Combinatory treatments using surgery, radiotherapy and/or chemotherapy together with immunotherapy have shown encouraging results for specific subsets of tumors, but a significant proportion of tumors remains unsusceptible. Some of these inconsistencies are thought to be the consequence of an immunosuppressive tumor microenvironment (TME) caused by therapy-induced tumor cell death (TCD). An increased understanding of the molecular mechanisms governing TCD has provided valuable insights in specific signaling cascades activated by treatment and the subsequent effects on the TME. Depending on the treatment variables of conventional chemo-, radio- and immunotherapy and the genetic composition of the tumor cells, particular cell death pathways are activated. Consequently, TCD can either have tolerogenic or immunogenic effects on the local environment and thereby affect the post-treatment anti-tumor response of immune cells. Thus, identification of these events can provide new rationales to increase the efficacy of conventional therapies combined with immunotherapies. In this review, we sought to provide an overview of the molecular mechanisms initiated by conventional therapies and the impact of treatment-induced TCD on the TME. We also provide some perspectives on how we can circumvent tolerogenic effects by adequate treatment selection and manipulation of key signaling cascades.

An independent predictor of poor prognosis in locally advanced rectal cancer: rs867228 in formyl peptide receptor 1 (FPR1)

Formyl peptide receptor 1 (FPR1) plays a key regulatory role in innate and adaptive immunity. Recently, we reported that the CC genotype of FPR1-E346A (rs867228, c. 1037 A > C) is an independent biomarker for patients with locally advanced rectal cancer (LARC) who received preoperative concurrent chemoradiotherapy (CCRT). Pharmacologic inhibition of FPR1 decreased the migration and infiltration of T lymphocytes into tumor microenvironment after CCRT.

Biomarkers of Radiotherapy-Induced Immunogenic Cell Death

Radiation therapy (RT) can induce an immunogenic variant of regulated cell death that can initiate clinically relevant tumor-targeting immune responses. Immunogenic cell death (ICD) is accompanied by the exposure and release of damage-associated molecular patterns (DAMPs), chemokine release, and stimulation of type I interferon (IFN-I) responses. In recent years, intensive research has unraveled major mechanistic aspects of RT-induced ICD and has resulted in the identification of immunogenic factors that are released by irradiated tumor cells. However, so far, only a limited number of studies have searched for potential biomarkers that can be used to predict if irradiated tumor cells undergo ICD that can elicit an effective immunogenic anti-tumor response. In this article, we summarize the available literature on potential biomarkers of RT-induced ICD that have been evaluated in cancer patients. Additionally, we discuss the clinical relevance of these findings and important aspects that should be considered in future studies.

Emerging Trends for Radio-Immunotherapy in Rectal Cancer

Rectal cancer is a heterogeneous disease at the genetic and molecular levels, both aspects having major repercussions on the tumor immune contexture. Whilst microsatellite status and tumor mutational load have been associated with response to immunotherapy, presence of tumor-infiltrating lymphocytes is one of the most powerful prognostic and predictive biomarkers. Yet, the majority of rectal cancers are characterized by microsatellite stability, low tumor mutational burden and poor T cell infiltration. Consequently, these tumors do not respond to immunotherapy and treatment largely relies on radiotherapy alone or in combination with chemotherapy followed by radical surgery. Importantly, pre-clinical and clinical studies suggest that radiotherapy can induce a complete reprograming of the tumor microenvironment, potentially sensitizing it for immune checkpoint inhibition. Nonetheless, growing evidence suggest that this synergistic effect strongly depends on radiotherapy dosing, fractionation and timing. Despite ongoing work, information about the radiotherapy regimen required to yield optimal clinical outcome when combined to checkpoint blockade remains largely unavailable. In this review, we describe the molecular and immune heterogeneity of rectal cancer and outline its prognostic value. In addition, we discuss the effect of radiotherapy on the tumor microenvironment, focusing on the mechanisms and benefits of its combination with immune checkpoint inhibitors.

Polymorphism of formyl peptide receptor 1 (FPR1) reduces the therapeutic efficiency and antitumor immunity after neoadjuvant chemoradiotherapy (CCRT) treatment in locally advanced rectal cancer

Immunosurveillance and immunoscavenging prompted by preoperative chemoradiotherapy (CCRT) may contribute to improve local control and increase survival outcomes for patients with locally advanced rectal cancer (LARC). In this study, we investigated several genotypes of pattern recognition receptors (PRRs) and their impact on therapeutic efficacy in LARC patients treated with CCRT. We found that homozygosis of formyl peptide receptor 1 (FPR1) (E346A/rs867228) was associated with reduced 5-year overall survival (OS) by Kaplan-Meier analysis (62% vs. 81%, p = 0.014) and multivariate analysis [hazard ratio (HR) = 3.383, 95% CI = 1.374-10.239, p = 0.007]. Moreover, in an animal model, we discovered that the FPR1 antagonist, Boc-MLF (Boc-1), reduced CCRT therapeutic efficacy and decreased cytotoxic T cells and T effector memory cells after chemoradiotherapy treatment. Pharmacologic inhibition of FPR1 by Boc-1 decreased T lymphocyte migration to irradiated tumor cells. Therefore, these results revealed that the FPR1 genotype participates in CCRT-elicited anticancer immunity by reducing T lymphocytes migration and infiltration, and that the FPR1-E346A CC genotype can be considered an independent biomarker for chemo- and radiotherapy outcomes.

Immunogenic Cell Death by the Novel Topoisomerase I Inhibitor TLC388 Enhances the Therapeutic Efficacy of Radiotherapy

Simple Summary

This study aims to evaluate the induction of immunogenic cell death (ICD) for anticancer immunity by the novel topoisomerase I inhibitor lipotecan. These results show that lipotecan can remarkably elicit ICD and increase tumor immunogenicity, which promotes the therapeutic efficacy of radiotherapy compared to conventional chemoradiotherapy in vivo. These results provide potential therapeutic strategies to improve the efficacy of chemoradiotherapy in colorectal cancer (CRC), which may increase the local control rate and decrease tumor relapse in locally advanced rectal cancer (LARC) patients who receive preoperative chemoradiotherapy.

Abstract

Rectal cancer accounts for 30–40% of colorectal cancer (CRC) and is the most common cancer-related death worldwide. The preoperative neoadjuvant chemoradiotherapy (neoCRT) regimen is the main therapeutic strategy for patients with locally advanced rectal cancer (LARC) to control tumor growth and reduce distant metastasis. However, 30–40% of patients achieve a partial response to neoCRT and suffer from unnecessary drug toxicity side effects and a risk of distant metastasis. In our study, we found that the novel topoisomerase I inhibitor lipotecan (TLC388) can elicit immunogenic cell death (ICD) to release damage-associated molecular patterns (DAMPs), including HMGB1, ANXA1, and CRT exposure. Lipotecan thereby increases cancer immunogenicity and triggers an antitumor immune response to attract immune cell infiltration within the tumor microenvironment (TME) in vitro and in vivo. Taken together, these results show that lipotecan can remodel the tumor microenvironment to provoke anticancer immune responses, which can provide potential clinical benefits to the therapeutic efficacy of neoCRT in LARC patients.

Effect of radiotherapy on T cell and PD-1 / PD-L1 blocking therapy in tumor microenvironment

Cancer is a worldwide problem that threatens human health. Radiotherapy plays an important role in a variety of cancer treatment methods. The administration of radiotherapy can alter the differentiation pathways and functions of T cells, which in turn improves the immune response of T cells. Radiotherapy can also induce up-regulation of PD-L1 expression, which means that it has great potential for enhancing the therapeutic effect of anti-PD-1/PD-L1 inhibitors and reducing the risk of drug resistance toward them. At present, the combination of radiotherapy and anti-PD-1/PD-L1 inhibitors has shown significant therapeutic effects in clinical tumor research. This review focuses on the mechanism of radiotherapy on T cells reported in recent years, as well as related research progress in the application of PD-1/PD-L1 blockers. It will provide a theoretical basis for the rational clinical application of radiotherapy combined with PD-1/PD-L1 inhibitors.

Prognostic relevance of programmed cell death 1 ligand 2 (PDCD1LG2/PD-L2) in patients with advanced stage colon carcinoma treated with chemotherapy

Colorectal cancer (CRC) is the leading cause of cancer-related mortality worldwide. Although the role of tumor programmed cell death 1 ligand 1 (PD-L1) in suppressing antitumor immunity has been validated in various malignances, the impact of PD-L2 (PD-L2/PDCD1LG2) within tumors remains elusive. Here, we examined tumor PD-L2 expression by immunohistochemical analysis and assessed its association with clinicopathological characteristics and the infiltration of intratumoral T lymphocytes in colon carcinoma patients (n = 1264). We found that tumor PD-L2 status was correlated with perineural invasion (PNI) and associated with survival outcome in colon carcinoma patients. The level of tumor PD-L2 was positively associated with tumor PD-L1 expression but inversely associated with the density of CD8⁺ tumor-infiltrating lymphocytes (TILs). Patients with elevated tumor PD-L2 levels had a favorable 5-year overall survival (OS) compared to patients with low PD-L2 levels (57% vs 40%, p < 0.001), especially in advanced stage colon carcinoma patients. Low tumor PD-L2 expression was associated with an increased 5-year OS risk among advanced stage colon carcinoma patients by univariate analysis [hazard ratio (HR) = 1.69, 95% CI 1.324–2.161, p < 0.001] and multivariate analysis [HR = 1.594, 95% CI 1.206–2.106, p = 0.001]. Moreover, tumor PD-L2 expression was inversely associated with the lymphocytic reaction in advanced stage colon carcinoma, suggesting that PD-L2 may be upregulated by a compensatory mechanism to inhibit T cell-mediated anticancer immunity. Taken together, these results show that tumor PD-L2 expression may be an independent prognostic factor for survival outcome in patients with advanced stage colon carcinoma.

A meta-analysis of CD274 (PD-L1) assessment and prognosis in colorectal cancer and its role in predicting response to anti-PD-1 therapy

BACKGROUND

PD-1 checkpoint inhibitors are novel therapeutic agents in colorectal cancer (CRC). Immunohistochemical staining for CD274 assessment is standardised in upper GI cancer, but not in CRC.

METHODS

Methodologies of relevant studies were scrutinized and meta-analysis of survival and CD274/PDCD1 performed. Furthermore, anti-PD-1 therapy clinical trial results in CRC were assessed with particular emphasis on CD274 assessment.

RESULTS

24 studies were included. CD274 on immune cells was associated with good prognosis. CD274 on tumour cells has heterogenous outcomes and does not meet requirements of a prognostic marker. As a marker of response to anti-PD-1 therapy, CD274 assessment is not standardised in CRC.

CONCLUSION

CD274 does not appear useful as a prognostic marker. As a marker of response to anti-PD-1 therapy, assessment methodology requires standardisation. As the Combined Positive Score (CPS) is used in upper GI cancer, this seems a logical method to adopt. Thresholds for CRC remain to be determined.

The Clinical Relevance of Frequent Germline Genetic Variants Detected by Targeted Sequencing in Patients With Rectal Adenocarcinoma (READ)

BACKGROUND

The progression of colorectal cancer (CRC) mainly stems from the occurrence of somatic mutation. However, there is little information that can be used to comprehensively analyse the importance of germline variants in CRC patients.

PATIENTS AND METHODS

The candidate germline variants between tumor relapse and cured rectal adenocarcinoma (READ) were firstly filtered by whole-exome sequencing (n=4), and validated by targeted sequencing and associated with clinical outcome in READ (n=48).

RESULTS

We identified 9 pathogenic germline variants that were clinically associated with survival outcome in READ, including TIPIN, TLR1, TLR10, OR4D6, IGSF3, UBBP4, OR6J1, FAM208A and DISC1. Patients carrying these germline susceptibility variants had an increased risk of poor survival outcome compared to those without these variants.

CONCLUSION

Not only the tumor genome, but also the germline sequence must be analysed to depict the overall genetic profile, providing potential therapeutic strategies for personalized medicine.

Circular RNA CirCHIPK3 promotes cell proliferation and invasion of breast cancer by sponging miR-193a/HMGB1/PI3K/AKT axis

Background

The aim of this study was to explore the potential mechanism of circular RNA (circRNA) CirCHIPK3 on the malignant proliferation and metastasis of breast cancer (BC).

Methods

Human BC samples and their matched normal adjacent tissues were obtained from 50 patients to assess the expression of CirCHIPK3 and its relationship with BC prognosis. A series of in vitro and in vivo functional experiments were carried out to elucidate the role of CirCHIPK3 in BC progression and its underlying molecular mechanisms. Moreover, the interaction of CirCHIPK3, miR‐193a, and HMGB1 was examined using bioinformatics, FISH, RIP, RNA‐pull down and luciferase reporter assays. Western blot analysis was performed to examine the expression of HMGB1, p‐PI3K, total PI3K, p‐AKT, and AKT after si‐CirCHIPK3 transfection.

Results

Upregulation of CirCHIPK3 was identified in BC, which predicted a worse prognosis in BC patients. Furthermore, it was found that CirCHIPK3 facilitated cell proliferation, migration, and invasion in BC by regulating miR‐193a/HMGB1/PI3K/AKT signaling. CirCHIPK3 acted as a sponge for miR‐193a to facilitate HMGB1 expression. si‐CirCHIPK3 also inhibited tumor growth of BC in nude mice. si‐CircCHIPK3 decreased HMGB1/PI3K/AKT signal expression in MDA‐MB‐231 cells, whereas overexpression of CircCHIPK3 enhanced HMGB1/PI3K/AKT signal.

Conclusions

CirCHIPK3 regulated miR‐193a/HMGB1/PI3K/AKT signaling to facilitate BC development and progression, providing a novel therapeutic target for BC.

High Mobility Group Box 1 in Human Cancer

High mobility group box 1 (HMGB1) is an extremely versatile protein that is located predominantly in the nucleus of quiescent eukaryotic cells, where it is critically involved in maintaining genomic structure and function. During cellular stress, however, this multifaceted, cytokine-like protein undergoes posttranslational modifications that promote its translocation to the cytosol, from where it is released extracellularly, either actively or passively, according to cell type and stressor. In the extracellular milieu, HMGB1 triggers innate inflammatory responses that may be beneficial or harmful, depending on the magnitude and duration of release of this pro-inflammatory protein at sites of tissue injury. Heightened awareness of the potentially harmful activities of HMGB1, together with a considerable body of innovative, recent research, have revealed that excessive production of HMGB1, resulting from misdirected, chronic inflammatory responses, appears to contribute to all the stages of tumorigenesis. In the setting of established cancers, the production of HMGB1 by tumor cells per se may also exacerbate inflammation-related immunosuppression. These pro-inflammatory mechanisms of HMGB1-orchestrated tumorigenesis, as well as the prognostic potential of detection of elevated expression of this protein in the tumor microenvironment, represent the major thrusts of this review.

IDO1 Expression Increased After Neoadjuvant Therapy Predicts Poor Pathologic Response and Prognosis in Esophageal Squamous Cell Carcinoma

Indoleamine 2,3-dioxygenase (IDO1) plays an important role in tumor immune evasion. In this study, we investigated the changes of tumor IDO1 expression and CD8+ tumor-infiltrating lymphocytes (TILs) status in tumor microenvironment (TME) after neoadjuvant chemoradiotherapy (NCRT) or neoadjuvant chemotherapy (NCT) in esophageal squamous cell carcinoma (ESCC), respectively. Moreover, the potential predictive value of the changes of tumor IDO1 expression and CD8+TILs status on pathologic response and clinical outcome was further evaluated. By matching propensity scores in 295 patients, a total of 85 ESCC patients with neoadjuvant therapy followed by surgery were recruited, including 17 patients with NCRT and 68 patients with NCT. Tumor IDO1 expression and CD8+TILs within TME in paired specimens were evaluated by immunohistochemistry, and the changes of tumor IDO1 expression and CD8+TILs between the paired specimens were estimated. Tumor IDO1 expression significantly increased from baseline to postoperative tumor tissue after NCT (p = 0.002), whereas no significant difference was detected after NCRT (p = 0.44). The density of CD8+TILs in the tumor-invasive margin increased significantly after neoadjuvant therapy, and there was no significant difference in density changes of CD8+TILs between the NCRT and NCT groups (p = 0.118). Upregulation of tumor IDO1 expression after neoadjuvant therapy was associated with poor pathologic response (p = 0.002). Lastly, multivariate Cox analysis showed that IDO1-rise patients after neoadjuvant therapy were related to poor prognosis (p = 0.047). These results indicated that chemotherapy could promote tumor IDO1 expression, and the increased tumor IDO1 expression after neoadjuvant therapy predicted poor pathologic response and prognosis in ESCC.

Decitabine Augments Chemotherapy-Induced PD-L1 Upregulation for PD-L1 Blockade in Colorectal Cancer

Programmed cell death-1 (PD-1) has demonstrated impressive clinical outcomes in several malignancies, but its therapeutic efficacy in the majority of colorectal cancers is still low. Therefore, methods to improve its therapeutic efficacy in colorectal cancer (CRC) patients need further investigation. Here, we demonstrate that immunogenic chemotherapeutic agents trigger the induction of tumor PD-L1 expression in vitro and in vivo, a fact which was validated in metastatic CRC patients who received preoperatively neoadjuvant chemotherapy (neoCT) treatment, suggesting that tumor PD-L1 upregulation by chemotherapeutic regimen is more feasible via PD-1/PD-L1 immunotherapy. However, we found that the epigenetic control of tumor PD-L1 via DNA methyltransferase 1 (DNMT1) significantly influenced the response to chemotherapy. We demonstrate that decitabine (DAC) induces DNA hypomethylation, which not only directly enhances tumor PD-L1 expression but also increases the expression of immune-related genes and intratumoral T cell infiltration in vitro and in vivo. DAC was found to profoundly enhance the therapeutic efficacy of PD-L1 immunotherapy to inhibit tumor growth and prolong survival in vivo. Therefore, it can be seen that DAC remodels the tumor microenvironment to improve the effect of PD-L1 immunotherapy by directly triggering tumor PD-L1 expression and eliciting stronger anti-cancer immune responses, providing potential clinical benefits to CRC patients in the future.

HMGB1: an overview of its versatile roles in the pathogenesis of colorectal cancer

BACKGROUND

In recent years, the high mobility group box-1 (HMGB1) protein, a damage-associated molecular pattern (DAMP) molecule, has been found to play multifunctional roles in the pathogenesis of colorectal cancer. Although much attention has been given to the diagnostic and prognostic values of HMGB1 in colorectal cancer, the exact functional roles of the protein as well as the mechanistic pathways involved have remained poorly defined. This systematic review aims to discuss what is currently known about the roles of HMGB1 in colorectal cancer development, growth and progression, and to highlight critical areas for future investigations. To achieve this, the bibliographic databases Pubmed, Scopus, Web of Science and ScienceDirect were systematically screened for articles from inception till June 2018, which address associations of HMGB1 with colorectal cancer.

CONCLUSIONS

HMGB1 plays multiple roles in promoting the pathogenesis of colorectal cancer, despite a few contradicting studies. HMGB1 may differentially regulate disease-related processes, depending on the redox status of the protein in colorectal cancer. Binding of HMGB1 to various protein partners may alter the impact of HMGB1 on disease progression. As HMGB1 is heavily implicated in the pathogenesis of colorectal cancer, it is crucial to further improve our understanding of the functional roles of HMGB1 not only in colorectal cancer, but ultimately in all types of cancers.

Circulating biomarkers of cell death

Numerous disease states are associated with cell death. For many decades, apoptosis and accidental necrosis have been assumed to be the two ways how a cell can die. The recent discovery of additional cell death processes such as necroptosis, ferroptosis or pyroptosis revealed a complex interplay between cell death mechanisms and diseases. Depending on the particular cell death pathway, cells secrete distinct molecular patterns, which differ between cell death types. This review focusses on released molecules, detectable in the blood flow, and their potential role as circulating biomarkers of cell death. We elucidate the molecular background of different biomarkers and give an overview on their correlation with disease stage, therapy response and prognosis in patients.

Dedifferentiation process driven by radiotherapy-induced HMGB1/TLR2/YAP/HIF-1α signaling enhances pancreatic cancer stemness

Differentiated cancer cells reacquiring stem cell traits following radiotherapy may enrich cancer stem cells and accelerate tumor recurrence and metastasis. We are interested in the mechanistic role of dying cells-derived HMGB1 in CD133- pancreatic cancer cells dedifferentiation following radiotherapy. We firstly confirmed that X-ray irradiation induced differentiation of CD133- pancreatic cancer cells, from either sorted from patient samples or established cell lines, into cancer stem-like cells (iCSCs). Using an in vitro coculture model, X-ray irradiation induced dying cells to release HMGB1, which further promoted CD133- pancreatic cancer cells regaining stem cell traits, such as higher sphere forming ability and expressed higher level of stemness-related genes and proteins. Inhibiting the expression and activity of HMGB1 attenuated the dedifferentiation stimulating effect of irradiated, dying cells on C133- pancreatic cancer cells in vitro and in PDX models. Mechanistically, HMGB1 binding with TLR2 receptor functions in a paracrine manner to affect CD133- pancreatic cancer cells dedifferentiation via activating Hippo-YAP pathway and HIF-1α expression in oxygen independent manner in vitro and in vivo. We conclude that X-ray irradiation induces CD133- pancreatic cancer cell dedifferentiation into a CSC phenotype, and inhibiting HMGB1 may be a strategy to prevent CSC enrichment and further pancreatic carcinoma relapse.

Prognostic relevance of programmed cell death-ligand 1 expression and CD8+ TILs in rectal cancer patients before and after neoadjuvant chemoradiotherapy

PURPOSE/BACKGROUND

Radiotherapy has been recently reported to boost the therapeutic response of immune checkpoint blockade (ICB); however, few studies have focused on programmed cell death-ligand 1 (PD-L1) expression in locally advanced rectal cancer (LARC) patients who receive preoperative neoadjuvant chemoradiotherapy (neoCRT). The aim of the present study was to investigate the PD-L1 expression status and CD8+ intra-tumoral infiltrating lymphocytes (TILs) before and after neoCRT and its association with clinicopathological characteristics in rectal cancer.

MATERIALS AND METHODS

Immunostainings of PD-L1 and CD8+ TILs were performed in 112 pair-matched LARC patients treated by neoCRT. Tumor PD-L1 expression and CD8+ TILs within the tumor microenvironment before and after neoCRT were evaluated via immunohistochemistry.

RESULTS

High tumor PD-L1 expression was significantly increased from 50 to 63%, and high CD8+ TILs counts were also slightly increased from 32 to 35% after neoCRT treatment. High tumor PD-L1 before and after neoCRT was associated with improved disease-free survival (DFS, pre-neoCRT: p = 0.003 and post-neoCRT: p = 0.003) and overall survival (OS, pre-neoCRT: p = 0.045 and post-neoCRT: p = 0.0001). High CD8+ TILs before neoCRT was associated with improved DFS (p = 0.057), and it was significantly associated with improved DFS after neoCRT (p = 0.039). Patients with high tumor PD-L1 and CD8+ TILs before and after neoCRT were significantly associated with improved DFS (pre-neoCRT: p = 0.004 and post-neoCRT: p = 0.006).

CONCLUSION

The present results provide evidence that tumor PD-L1 expression and recruitment of CD8+ TILs within the tumor microenvironment were increased by neoCRT treatment. Tumor PD-L1 and CD8+ TILs are prognostic biomarkers for the survival of LARC patients treated with neoCRT.