Cancer immunotherapy resistance based on immune checkpoints inhibitors: Targets, biomarkers, and remedies

Pyroptosis correlates with tumor immunity and prognosis

Pyroptosis, as a proinflammatory form of regulated cell death, plays an important role in multiple cancers. However, the diagnostic and prognostic values of pyroptosis and its interaction with tumor immunity in pan-cancer are still unclear. Here, we show an elevated general expression of 17 pyroptosis-associated genes of tumor patients with high-immune-activity and a reduced pyroptosis in low-immune-activity tumors. Moreover, pyroptosis is positively correlated with immune infiltration and immune-related signatures across 30 types of cancer. Furthermore, our experimental data suggest that pyroptosis directly modulate the expression of immune checkpoint molecules and cytokines. We generate a pyroptosis score model as a potential independent prognostic indicator in melanoma patients. Interestingly, 3 of pyroptosis-associated genes including CASP1, CASP4 and PYCARD, can predict the effectiveness of anti-PD-1 immunotherapy for patients with melanoma. Our study demonstrates that pyroptosis correlates with tumor immunity and prognosis, might be used as a potential target for immune therapy.

A pan-cancer analysis demonstrates that pyroptosis is involved in tumor development, prognosis and immunotherapy through the promotion of tumor immunity.

MCEMP1 is a potential therapeutic biomarker associated with immune infiltration in advanced gastric cancer microenvironment

BACKGROUND

Over the last decade, breakthroughs have been made in cancer immunotherapy. However, for advanced gastric cancer (AGC), the complexity and heterogeneity of the tumor microenvironment (TME) has been the biggest challenge for immunotherapy. Therefore, an intensive study on TME of AGC is necessary.

METHODS

ESTIMATE and CIBERSORT algorithms were applied to analyze the transcriptome data of AGC using TCGA database systematically. We identified mast cell-expressed membrane protein 1 (MCEMP1) as a potential prognostic marker by protein-protein interaction (PPI) and Univariate Cox regression. The expression of MCEMP1 was evaluated by immunohistochemistry (IHC) and quantitative real time PCR. We assessed prognostic values of MCEMP1 with use of Kaplan-Meier and Multivariate Cox regression analysis. Gene set enrichment analysis (GSEA) was used to analyze the molecular mechanism of MCEMP1. The correlation between MCEMP1 expression and tumor immune infiltration was analyzed by the TIMER database and CIBERSORT algorithm, which was confirmed by IHC.

RESULTS

The mRNA and protein expression of MCEMP1 was up-regulated substantially and related to poor survival in AGC. GSEA analysis revealed that MCEMP1 was involved in the immune-related signaling pathways. We further demonstrated that the expression of MCEMP1 was correlated with multiple immune cells and immune checkpoints. The results of IHC indicated that there was a positive correlation between PD-L1 expression and MCEMP1, suggesting that MCEMP1 may affect the prognosis of AGC patients by regulating immune infiltration and the function of immune cells.

CONCLUSION

MCEMP1 may serve as a biomarker associated with immune infiltration in TME and could be a potential therapeutic target for AGC patients.

Stereotactic body radiotherapy extends the clinical benefit of PD-1 inhibitors in refractory recurrent/metastatic nasopharyngeal carcinoma

Purpose

Emerging evidence shows that immune checkpoint inhibitors lead to durable responses in a variety of cancers, including nasopharyngeal carcinoma (NPC), however, combination approaches (i.e., stereotactic body radiation therapy, SBRT) are required to extend this benefit beyond a subset of patients. This study retrospectively evaluated eight recurrent/metastatic NPC patients, to investigate how radiation could potentiate PD-1 checkpoint inhibition therapy.

Methods

Between September 2016 and July 2017, eight consecutive cases with histologically confirmed PDL1-positive status, for which prior standard therapy had been ineffective (five patients), were treated at our institution and Macao Clinics and two patients had disease progression within 6 months of completion of definitive chemoradiation, or one patient refused to receive chemoradiotherapy. All received PD-1 inhibitors first, seven of them accepted SBRT with an unmodified PD-1 inhibitors regimen after first evaluation as they were unresponsive to PD-1 inhibitors alone. Treatment was discontinued as long as patients were experiencing a clinical benefit in the opinion of the physicians and at least five cycles were given before stoppage.

Results

Median follow-up time was 56.7 months. The confirmed objective response rate based on RECIST-v1.1 at first evaluation was 12.5% (1/8). For the seven cases who received SBRT, six of them experience an objective response (6/7, 85.7%) after SBRT. Only one patient showed rapid progress and die within 95 days after the initiation of SBRT intervention. Three patients who did not have all lesions exposed to irradiation were available to evaluate the incidence of an abscopal effect, however, it did not occur as expected. Median PFS and OS for the seven patients were 8.0 and 30.8 months after SBRT intervention, respectively. Two-year OS as indicated was 71.0%.

Conclusions

PD-1 inhibitors combined with SBRT demonstrated promising antitumor activity in patients with PD-L1 positive RM-NPC. Patients may benefit from continue immunotherapy beyond disease progression when SBRT was introduced.

PMS2 Expression With Combination of PD-L1 and TILs for Predicting Survival of Esophageal Squamous Cell Carcinoma

Background

DNA mismatch repair (MMR) deficiency (dMMR) has been recognized as an important biomarker for immunotherapy in esophageal squamous cell carcinoma (ESCC), along with programmed death ligand 1 (PD-L1) expression and/or tumor-infiltrated lymphocytes (TILs). However, in ESCC, MMR protein assessment has not been well studied at present.

Methods

A total of 484 ESCC tissues treated between 2007 and 2010, in our hospital, were enrolled. Immunohistochemical expression of MLH1, MSH2, MSH6, PMS2, and PD-L1 on tissue microarray specimens and clinicopathological features, including TILs, were analyzed retrospectively.

Results

Out of the 484 studied cases, loss of MLH1, MSH2, MSH6, and PMS2 expression were found in 6.8%, 2.1%, 8.7%, and 4.8% patients, respectively. dMMR was found in 65 patients, 37 cases involved in one MMR protein, 17 cases involved in two proteins, 7 cases involved in three proteins, and 4 cases involved in four proteins. There was no significant survival difference between pMMR (MMR-proficient) and dMMR patients (P>0.05). However, 224 patients with low PMS2 expression had better DFS and OS than 260 patients with high PMS2 expression (P=0.006 for DFS and 0.008 for OS), which was identified as an independent prognostic factor in multivariate analyses. Positive PD-L1 expression was detected in 341 (70.5%) samples. In stage I-II disease, patients with PD-L1 expression had better DFS and OS than those without PD-L1 expression(P<0.05), which was not found in stage III-IV disease. With the ITWG system, 40.1% of cases were classified as high TILs. Patients in the high-TILs group tended to have better DFS (P=0.055) and OS (P=0.070) than those in the low-TILs group and the differences were statistically significant in pMMR, high MSH6, or PMS2 expression cases (P<0.05). Also, high PMS2 expression patients with both PD-L1 expression and high TILs, had similar DFS and OS compared with low PMS2 expression patients (P>0.05), which were much better than other high PMS2 expression patients.

Conclusion

The expression level of MMR proteins could also be used as a prognostic factor in ESCC and PMS2 expression outperformed other MMR proteins for predicting survival. The combination of PD-L1 expression and TILs may lead to more efficient risk stratification of ESCC.

Pharmacological Properties of 4', 5, 7-Trihydroxyflavone (Apigenin) and Its Impact on Cell Signaling Pathways

Plant bioactive compounds, particularly apigenin, have therapeutic potential and functional activities that aid in the prevention of infectious diseases in many mammalian bodies and promote tumor growth inhibition. Apigenin is a flavonoid with low toxicities and numerous bioactive properties due to which it has been considered as a traditional medicine for decades. Apigenin shows synergistic effects in combined treatment with sorafenib in the HepG2 human cell line (HCC) in less time and statistically reduces the viability of tumor cells, migration, gene expression and apoptosis. The combination of anti-cancerous drugs with apigenin has shown health promoting potential against various cancers. It can prevent cell mobility, maintain the cell cycle and stimulate the immune system. Apigenin also suppresses mTOR activity and raises the UVB-induced phagocytosis and reduces the cancerous cell proliferation and growth. It also has a high safety threshold, and active (anti-cancer) doses can be gained by consuming a vegetable and apigenin rich diet. Apigenin also boosted autophagosome formation, decreased cell proliferation and activated autophagy by preventing the activity of the PI3K pathway, specifically in HepG2 cells. This paper provides an updated overview of apigenin's beneficial anti-inflammatory, antibacterial, antiviral, and anticancer effects, making it a step in the right direction for therapeutics. This study also critically analyzed the effect of apigenin on cancer cell signaling pathways including the PI3K/AKT/MTOR, JAK/STAT, NF-κB and ERK/MAPK pathways.

The strategic roles of four enzymes in the interconnection between metabolism and oncogene activation in non-small cell lung cancer: Therapeutic implications

NSCLC is the leading cause of cancer mortality and represents a major challenge in cancer therapy. Intrinsic and acquired anticancer drug resistance are promoted by hypoxia and HIF-1α. Moreover, chemoresistance is sustained by the activation of key signaling pathways (such as RAS and its well-known downstream targets PI3K/AKT and MAPK) and several mutated oncogenes (including KRAS and EGFR among others). In this review, we highlight how these oncogenic factors are interconnected with cell metabolism (aerobic glycolysis, glutaminolysis and lipid synthesis). Also, we stress the key role of four metabolic enzymes (PFK1, dimeric-PKM2, GLS1 and ACLY), which promote the activation of these oncogenic pathways in a positive feedback loop. These four tenors orchestrating the coordination of metabolism and oncogenic pathways could be key druggable targets for specific inhibition. Since PFK1 appears as the first tenor of this orchestra, its inhibition (and/or that of its main activator PFK2/PFKFB3) could be an efficacious strategy against NSCLC. Citrate is a potent physiologic inhibitor of both PFK1 and PFKFB3, and NSCLC cells seem to maintain a low citrate level to sustain aerobic glycolysis and the PFK1/PI3K/EGFR axis. Awaiting the development of specific non-toxic inhibitors of PFK1 and PFK2/PFKFB3, we propose to test strategies increasing citrate levels in NSCLC tumors to disrupt this interconnection. This could be attempted by evaluating inhibitors of the citrate-consuming enzyme ACLY and/or by direct administration of citrate at high doses. In preclinical models, this "citrate strategy" efficiently inhibits PFK1/PFK2, HIF-1α, and IGFR/PI3K/AKT axes. It also blocks tumor growth in RAS-driven lung cancer models, reversing dedifferentiation, promoting T lymphocytes tumor infiltration, and increasing sensitivity to cytotoxic drugs.

PD-L2 Serves as a Potential Prognostic Biomarker That Correlates With Immune Infiltration and May Predict Therapeutic Sensitivity in Lower-Grade Gliomas

Although patients with lower-grade gliomas (LGGs; grades II and III) have a relatively favorable prognosis, patients frequently relapse and tend to progress to higher-grade gliomas, leading to treatment resistance, poor survival, and ultimately treatment failure. However, until now, thorough research has not yet been reported on the relationship between PD-L2 and immune infiltration and therapeutic sensitivity to immunotherapy and TMZ-based chemotherapy of LGGs. In this study, we found that the expression of PD-L2 is upregulated in glioma, with high PD-L2 expression predicting a worse prognosis. Univariate and multivariate Cox regression analysis both indicated that PD-L2 represented an independent prognostic factor with high accuracy in survival prediction for LGGs. A nomogram comprising of age, grade, IDH mutation, and PD-L2 was established for predicting OS. Additionally, PD-L2 was found to be remarkably correlated with immune infiltration and some anti-tumor immune functions. The degree of PD-L2 expression was also found to be strongly related to the prediction of therapeutic sensitivity to immunotherapy and TMZ-based chemotherapy. Furthermore, immunohistochemistry demonstrated that PD-L2 and the macrophage biomarker CD68 were both increased in glioma, with PD-L2 expression having a strong positive connection with CD68 expression. Taken together, PD-L2 is a prognostic biomarker for LGGs patients that may provide novel insights into glioma individualized therapeutic strategies and guide effective immunotherapy and chemotherapy.

Transcriptome Analysis Reveals the Immune Infiltration Profiles in Cervical Cancer and Identifies KRT23 as an Immunotherapeutic Target

Cervical cancer (CC) is one of the most common malignancies in women worldwide. Dismal prognosis rates have been associated with conventional therapeutic approaches, emphasizing the need for new strategies. Recently, immunotherapy has been used to treat various types of solid tumors, and different subtypes of the tumor microenvironment (TME) are associated with diverse responses to immunotherapy. Accordingly, understanding the complexity of the TME is pivotal for immunotherapy. Herein, we used two methods, “ssGSEA” and “xCell,” to identify the immune profiles in CC and comprehensively assess the relationship between immune cell infiltration and genomic alterations. We found that more adaptive immune cells were found infiltrated in tumor tissues than in normal tissues, whereas the opposite was true for innate cells. Consensus clustering of CC samples based on the number of immune cells identified four clusters with different survival and immune statuses. Then, we subdivided the above four clusters into “hot” and “cold” tumors, where hot tumors exhibited higher immune infiltration and longer survival time. Enrichment analyses of differentially expressed genes (DEGs) revealed that the number of activated immune signaling pathways was higher in hot tumors than that in cold tumors. Keratin, type I cytoskeletal 23 (KRT23), was upregulated in cold tumors and negatively correlated with immune cell infiltration. In vitro experiments, real-time reverse transcription-quantitative polymerase chain reaction, cytometric bead arrays, and ELISA revealed that knockdown of KRT23 expression could promote the secretion of C-C motif chemokine ligand-5 and promote the recruitment of CD8⁺ T cells. We also constructed a model based on DEGs that exhibited a high predictive power for the survival of CC patients. Overall, our study provides deep insights into the immune cell infiltration patterns of CC. Moreover, KRT23 has huge prospects for application as an immunotherapeutic target. Finally, our model demonstrated a good predictive power for the prognosis of CC patients and may guide clinicians during immunotherapy.

Role of TNFSF9 bidirectional signal transduction in antitumor immunotherapy

The complex structure of the tumor microenvironment leads to the poor efficacy of tumor immunotherapy. The therapeutic adjuvant designed to enhance the effect of T cells by acting on the costimulatory molecule tumor necrosis factor superfamily member 9 (TNFSF9) has achieved good results. However, because some tumors are characterized by reduced T-cell infiltration, adjuvants acting on T cells alone may have limitations. On the other hand, the blockade of TNFSF9 reverse signalling can have an antitumor effect by reshaping the tumor microenvironment. Therefore, this paper mainly discusses the current status and potential of TNFSF9 bidirectional signalling in antitumor immunotherapy to provide new ideas for tumor immunotherapy.

PAMAM Dendritic Nanoparticle-Incorporated Hydrogel to Enhance the Immunogenic Cell Death and Immune Response of Immunochemotherapy

The efficiency of chemotherapy is frequently affected by its multidrug resistance, immune suppression, and severe side effects. Its combination with immunotherapy to reverse immune suppression and enhance immunogenic cell death (ICD) has emerged as a new strategy to overcome the aforementioned issues. Herein, we construct a pH-responsive PAMAM dendritic nanocarrier-incorporated hydrogel for the co-delivery of immunochemotherapeutic drugs. The stepwise conjugation of moieties and drug load was confirmed by various techniques. In vitro experimental results demonstrated that PAMAM dendritic nanoparticles loaded with a combination of drugs exhibited spherical nanosized particles, facilitated the sustained release of drugs, enhanced cellular uptake, mitigated cell viability, and induced apoptosis. The incorporation of PAB-DOX/IND nanoparticles into thermosensitive hydrogels also revealed the formation of a gel state at a physiological temperature and further a robust sustained release of drugs at the tumor microenvironment. Local injection of this formulation into HeLa cell-grafted mice significantly suppressed tumor growth, induced immunogenic cell death-associated cytokines, reduced cancer cell proliferation, and triggered a CD8⁺ T-cell-mediated immune response without obvious systemic toxicity, which indicates a synergistic ICD effect and reverse of immunosuppression. Hence, the localized delivery of immunochemotherapeutic drugs by a PAMAM dendritic nanoparticle-incorporated hydrogel could provide a promising strategy to enhance antitumor activity in cancer therapy.

Novel Hypoxia-Associated Gene Signature Depicts Tumor Immune Microenvironment and Predicts Prognosis of Colon Cancer Patients

Hypoxia, a typical hallmark of numerous tumors, indicates poor infiltration of antitumor lymphocytes, as well as facilitates the development, progression, and drug resistance of malignant cells. Here, the present research was performed to identify novel hypoxia-related molecular markers and their correlation to the tumor immune microenvironment (TIME) in colon cancer. The expression of hypoxia-related gene signature was extracted from The Cancer Genome Atlas (TCGA) COAD cohort. Based on this signature, a risk score model was constructed using the Lasso regression model. Its discrimination ability and stability were validated in another independent cohort (GSE17536) from Gene Expression Omnibus (GEO) database. Moreover, molecular biology experiments (quantitative real-time PCR and multiple immunohistochemistry) were performed to validate the results of bioinformatics analyses. Three hub genes, including PPFIA4, SERPINE1, and STC2, were chosen to build the risk score model. All of these genes were increasingly expressed in the hypoxia subgroup (HS). Compared with the normoxia subgroup (NS), HS had worse pathological features (T, N, M, and stage) and overall survival (OS), more expression of immune checkpoint molecules, poorer infiltration of some pro-inflammation immune cells (CD4⁺ T cells and CD8⁺ T cells), and enriched infiltration of M0/M2 macrophages. After the risk model was proven to be valuable and stable, a nomogram was built based on this model and some clinicopathological factors. Moreover, it had been identified that three hub genes were all increasingly expressed in hypoxic conditions by quantitative real-time PCR (qPCR). The results of multiple immunohistochemistry (mIHC) also showed that higher expression of hub genes was associated with poorer infiltration of pro-inflammation immune cells (CD8⁺ T cells and M1 macrophages) and richer infiltration of anti-inflammation immune cells (Treg cells and M2 macrophages). In conclusion, the present study uncovered the relations among hypoxia, TIME, and clinicopathological features of colon cancer. It might provide new insight and a potential therapeutic target for immunotherapy.

Recent advances in targeted drug delivery systems for resistant colorectal cancer

Colorectal cancer (CRC) is one of the deadliest cancers in the world, the incidences and morality rate are rising and poses an important threat to the public health. It is known that multiple drug resistance (MDR) is one of the major obstacles in CRC treatment. Tumor microenvironment plus genomic instability, tumor derived exosomes (TDE), cancer stem cells (CSCs), circulating tumor cells (CTCs), cell-free DNA (cfDNA), as well as cellular signaling pathways are important issues regarding resistance. Since non-targeted therapy causes toxicity, diverse side effects, and undesired efficacy, targeted therapy with contribution of various carriers has been developed to address the mentioned shortcomings. In this paper the underlying causes of MDR and then various targeting strategies including exosomes, liposomes, hydrogels, cell-based carriers and theranostics which are utilized to overcome therapeutic resistance will be described. We also discuss implication of emerging approaches involving single cell approaches and computer-aided drug delivery with high potential for meeting CRC medical needs.

Assessing the Potential Prognostic and Immunological Role of TK1 in Prostate Cancer

Background: It has been reported that thymidine kinase 1 (TK1) was up-regulated in multiple malignancies and participated in the regulation of tumor malignant behavior. However, its specific role in prostate cancer (PCa) remains unclear. Methods: TK1 expression in PCa patients and cell lines was identified via crossover analysis of the public datasets. A series of in vitro experiments and in vivo models was applied to investigate the function of TK1 in PCa. Functional enrichment analyses were further conducted to explore the underlying mechanism. Additionally, TISIDB was applied to explore the correlation between TK1 expression and tumor-infiltrating lymphocytes, immune subtypes, and immune regulatory factors. Results: TK1 expression was significantly up-regulated in PCa patients and cell lines. TK1 ablation inhibited tumor cell proliferation and migration potential, and in vivo experiments showed that TK1 inactivation can significantly restrain tumor growth. Functional enrichment analysis revealed TK1-related hub genes (AURKB, CCNB2, CDC20, CDCA5, CDK1, CENPA, CENPM, KIF2C, NDC80, NUF2, PLK1, SKA1, SPC25, ZWINT), and found that TK1 was closely involved in the regulation of cell cycle. Moreover, elevated mRNA expression of TK1 was related with higher Gleason score, higher clinical stage, higher pathological stage, higher lymph node stage, shorter overall survival, and DFS in PCa patients. Particularly, TK1 represented attenuated expression in C3 PCa and was related with infiltration of CD4+, CD8+ T cells, and dendritic cells as well as immunomodulator expression. Conclusion: Our study indicates that TK1 is a prognostic predictor correlated with poor outcomes of PCa patients, and for the first time represented that TK1 can promote the progression of PCa. Therefore, TK1 may be a potential diagnostic and prognostic biomarker, as well as a therapeutic target for PCa.

Central Role of the Antigen-Presentation and Interferon-γ Pathways in Resistance to Immune Checkpoint Blockade

Resistance to immunotherapy is due in some instances to the acquired stealth mechanisms of tumor cells that lose expression of MHC class I antigen–presenting molecules or downregulate their class I antigen–presentation pathways. Most dramatically, biallelic β2-microglobulin (B2M) loss leads to complete loss of MHC class I expression and to invisibility to CD8+ T cells. MHC class I expression and antigen presentation are potently upregulated by interferon-γ (IFNγ) in a manner that depends on IFNγ receptor (IFNGR) signaling via JAK1 and JAK2. Mutations in these molecules lead to IFNγ unresponsiveness and mediate loss of recognition and killing by cytotoxic T lymphocytes. Loss of MHC class I augments sensitivity of tumor cells to be killed by natural killer (NK) lymphocytes, and this mechanism could be exploited to revert resistance, for instance, with interleukin-2 (IL-2)-based agents. Moreover, in some experimental models,potent local type I interferon responses, such as those following intratumoral injection of Toll-like receptor 9 (TLR9) or TLR3 agonists, revert resistance due to mutations of JAKs.

Cancer combination therapies by angiogenesis inhibitors; a comprehensive review

Abnormal vasculature is one of the most conspicuous traits of tumor tissue, largely contributing to tumor immune evasion. The deregulation mainly arises from the potentiated pro-angiogenic factors secretion and can also target immune cells' biological events, such as migration and activation. Owing to this fact, angiogenesis blockade therapy was established to fight cancer by eliminating the nutrient and oxygen supply to the malignant cells by impairing the vascular network. Given the dominant role of vascular-endothelium growth factor (VEGF) in the angiogenesis process, the well-known anti-angiogenic agents mainly depend on the targeting of its actions. However, cancer cells mainly show resistance to anti-angiogenic agents by several mechanisms, and also potentiated local invasiveness and also distant metastasis have been observed following their administration. Herein, we will focus on clinical developments of angiogenesis blockade therapy, more particular, in combination with other conventional treatments, such as immunotherapy, chemoradiotherapy, targeted therapy, and also cancer vaccines. Video abstract.

Identification of the Tumor Immune Microenvironment and Therapeutic Biomarkers by a Novel Molecular Subtype Based on Aging-Related Genes in Hepatocellular Carcinoma

Background

Hepatocellular carcinoma (HCC) is one of the most prevalent malignant tumors with poor prognosis. Increasing evidence has revealed that immune cells and checkpoints in the tumor microenvironment (TME) and aging are associated with the prognosis of HCC. However, the association between aging and the tumor immune microenvironment (TIME) in HCC is still unclear.

Methods

RNA expression profiles and clinical data concerning HCC were downloaded from The Cancer Genome Atlas (TCGA) and Gene Expression Omnibus (GEO) databases. Based on differentially expressed aging-related genes (DEAGs), unsupervised clustering was used to identify a novel molecular subtype in HCC. The features of immune cell infiltration and checkpoints were further explored through CIBERSORTx. Enrichment analysis and both univariate and multivariate Cox analyses were conducted to construct a 3-gene model for predicting prognosis and chemosensitivity. Finally, the mRNA and protein expression levels of the 3 genes were verified in HCC and other cancers through database searches and experiments.

Results

Eleven differentially expressed AGs (GHR, APOC3, FOXM1, PON1, TOP2A, FEN1, HELLS, BUB1B, PPARGC1A, PRKDC, and H2AFX) correlated with the prognosis of HCC were used to divide HCC into two subtypes in which the prognosis was different. In cluster 2, which had a poorer prognosis, the infiltration of naive B cells and monocytes was lower in the TCGA and GEO cohorts, while the infiltration of M0 macrophages was higher. In addition, the TCGA cohort indicated that the microenvironment of cluster 2 had more immunosuppression through immune checkpoints. Enrichment analysis suggested that the MYC and E2F targets were positively associated with cluster 2 in the TCGA and GEO cohorts. Additionally, 3 genes (HMGCS2, SLC22A1, and G6PD) were screened to construct the prognostic model through univariate/multivariate Cox analysis. Then, the model was validated through the TCGA validation set and GEO dataset (GSE54236). Cox analysis indicated that the risk score was an independent prognostic factor and that patients in the high-risk group were sensitive to multiple targeted drugs (sorafenib, gemcitabine, rapamycin, etc.). Finally, significantly differential expression of the 3 genes was detected across cancers.

Conclusion

We systematically described the immune differences in the TME between the molecular subtypes based on AGs and constructed a novel three-gene signature to predict prognosis and chemosensitivity in patients with HCC.

Revolutionization in Cancer Therapeutics via Targeting Major Immune Checkpoints PD-1, PD-L1 and CTLA-4

Numerous research reports have witnessed dramatic advancements in cancer therapeutic approaches through immunotherapy. Blocking immunological checkpoint pathways (mechanisms employed by malignant cells to disguise themselves as normal human body components) has emerged as a viable strategy for developing anticancer immunity. Through the development of effective immune checkpoint inhibitors (ICIs) in multiple carcinomas, advances in cancer immunity have expedited a major breakthrough in cancer therapy. Blocking a variety of ICIs, such as PD-1 (programmed cell death-1), programmed cell death-ligand 1 (PD-L1), and cytotoxic T-lymphocyte-associated protein 4 (CTLA-4) has improved the immune system’s efficacy in combating cancer cells. Recent studies also supported the fact that ICIs combined with other potent antitumor candidates, such as angiogenic agents, could be a solid promising chemopreventive therapeutic approach in improving the effectiveness of immune checkpoint inhibitors. Immune checkpoint blockade has aided antiangiogenesis by lowering vascular endothelial growth factor expression and alleviating hypoxia. Our review summarized recent advances and clinical improvements in immune checkpoint blocking tactics, including combinatorial treatment of immunogenic cell death (ICD) inducers with ICIs, which may aid future researchers in creating more effective cancer-fighting strategies.

Heterogeneity induced GZMA-F2R communication inefficient impairs antitumor immunotherapy of PD-1 mAb through JAK2/STAT1 signal suppression in hepatocellular carcinoma

Tumor heterogeneity has been associated with immunotherapy and targeted drug resistance in hepatocellular carcinoma (HCC). However, communications between tumor and cytotoxic cells are poorly understood to date. In the present study, thirty-one clusters of cells were discovered in the tumor tissues and adjacent tissues through single-cell sequencing. Moreover, the quantity and function exhaustion of cytotoxic cells was observed to be induced in tumors by the TCR and apoptosis signal pathways. Furthermore, granzyme failure of cytotoxic cells was observed in HCC patients. Importantly, the GZMA secreted by cytotoxic cells was demonstrated to interact with the F2R expressed by the tumor cells both in vivo and in vitro. This interaction induced tumor suppression and T cell-mediated killing of tumor cells via the activation of the JAK2/STAT1 signaling pathway. Mechanistically, the activation of JAK2/STAT1 signaling promoted apoptosis under the mediating effect of the LDPRSFLL motif at the N-terminus of F2R, which interacted with GZMA. In addition, GZMA and F2R were positively correlated with PD-1 and PD-L1 in tumor tissues, while the expressions of F2R and GZMA promoted PD-1 mAb-induced tumor suppression in both mouse model and HCC patients. Finally, in HCC patients, a low expression of GZMA and F2R in the tumor tissues was correlated with aggressive clinicopathological characteristics and poor prognosis. Collectively, GZMA-F2R communication inefficient induces deficient PD-1 mAb therapy and provide a completely novel immunotherapy strategy for tumor suppression in HCC patients.

Boosting antitumor response with PSMA-targeted immunomodulatory VLPs, harboring costimulatory TNFSF ligands and GM-CSF cytokine

Therapeutic strategies based on immunomodulation have improved cancer therapy. Most approaches target co-stimulatory pathways or the inhibition of immunosuppressive mechanisms, to enhance immune response and overcome the immune tolerance of tumors. Here, we propose a novel platform to deliver targeted immunomodulatory signaling, enhancing antitumor response. The platform is based on virus-like particles derived from lentiviral capsids. These particles may be engineered to harbor multifunctional ligands on the surface that drive tropism to the tumor site and deliver immunomodulatory signaling, boosting the antitumor response. We generated virus-like particles harboring a PSMA-ligand, TNFSF co-stimulatory ligands 4-1BBL or OX40L, and a membrane-anchored GM-CSF cytokine. The virus-like particles are driven to PSMA-expressing tumors and deliver immunomodulatory signaling from the TNFSF surface ligands and the anchored GM-CSF, inducing T cell proliferation, inhibition of regulatory T cells, and potentiating elimination of tumor cells. The PSMA-targeted particles harboring immunomodulators enhanced antitumor activity in immunocompetent challenged mice and may be explored as a potential tool for cancer immunotherapy.

Pan-Cancer Analysis Identified CD93 as a Valuable Biomarker for Predicting Patient Prognosis and Immunotherapy Response

Background: The rapid development of immunotherapy has significantly improved patient outcomes in recent years. CD93, a novel biomarker expressed on vascular endothelial cells, is essential for tumor angiogenesis. Recent studies have shown that CD93 is closely related to immune cell infiltration and immunotherapy. However, its role in pan-cancer has not been reported.

Methods: The Cancer Genome Atlas (TCGA), Human Protein Atlas (HPA), cbioportal, Gene Expression Omnibus (GEO), Tumor Immune Estimation Resource (TIMER2.0), and the Tumor–Immune System Interactions and Drug Bank (TISIDB) databases were used to analyze CD93 in pan-cancers. R software was used for statistical analysis and mapping.

Results: There were significant differences in the expression of CD93 between tumor tissues and adjacent normal tissues in pan-cancer. The high expression of CD93 was associated with poor prognosis and high TNM stage in multiple tumor types. However, a high expression of CD93 was a protective factor in kidney renal clear cell carcinoma (KIRC). In addition, CD93 was closely related to immune cell infiltration in tumor tissues. Moreover, CD93 presented a robust correlation with immune modulators and immunotherapeutic markers [e.g., tumor mutation burden (TMB) and microsatellite instability (MSI)]. The results of gene set enrichment analysis (GSEA) showed that CD93 was correlated with tumor angiogenesis. Importantly, patients with a low expression of CD93 were more sensitive to immunotherapy in urothelial cancer.

Conclusion: CD93, which is involved in various immune responses, controls immune cell infiltration and impacts on the malignant properties of various cancer types. Therefore, CD93 has potential value to be biomarker for determining the prognosis and immune infiltration in multiple cancers.

Comparison of Laboratory Methods for the Clinical Follow Up of Checkpoint Blockade Therapies in Leukemia: Current Status and Challenges Ahead

The development of immune checkpoint inhibitors, the monoclonal antibodies that modulate the interaction between immune checkpoint molecules or their ligands on the immune cells or tumor tissue has revolutionized cancer treatment. While there are various studies proving their efficacy in hematological malignancies, there is also a body of accumulating evidence indicating that immune checkpoint inhibitors’ clinical benefits are limited in such diseases. In addition, due to their regulatory nature that balances the immune responses, blockade of immune checkpoints may lead to toxic side effects and autoimmune responses, and even primary or acquired resistance mechanisms may restrict their success. Thus, the need for laboratory biomarkers to identify and monitor patient populations who are more likely respond to this type of therapy and the management of side effects seem critical. However, guidelines regarding the use of immune checkpoint inhibitors in hematological cancers and during follow-up are limited while there is no consensus on the laboratory parameters to be investigated for safety and efficacy of the treatment. This review aims to provide an insight into recent information on predictive and prognostic value of biomarkers and laboratory tests for the clinical follow up of hematological malignancies, with an emphasis on leukemia.

Immunomodulatory potential of natural products from herbal medicines as immune checkpoints inhibitors: Helping to fight against cancer via multiple targets

Immunotherapy sheds new light to cancer treatment and is satisfied by cancer patients. However, immunotoxicity, single‐source antibodies, and single‐targeting stratege are potential challenges to the success of cancer immunotherapy. A huge number of promising lead compounds for cancer treatment are of natural origin from herbal medicines. The application of natural products from herbal medicines that have immunomodulatory properties could alter the landscape of immunotherapy drastically. The present study summarizes current medication for cancer immunotherapy and discusses the potential chemicals from herbal medicines as immune checkpoint inhibitors that have a broad range of immunomodulatory effects. Therefore, this review provides valuable insights into the efficacy and mechanism of actions of cancer immunotherapies, including natural products and combined treatment with immune checkpoint inhibitors, which could confer an improved clinical outcome for cancer treatment.

Magnetic hyperthermia induces effective and genuine immunogenic tumor cell death with respect to exogenous heating

This study systematically verified that magnetic hyperthermia (MH) with intracellular heating can induce genuine immunogenic tumor cell death for effective antitumor therapy, while exogenous heating fails to elicit this effect.

Comprehensive analysis of PD-L1 expression, tumor-infiltrating lymphocytes, and tumor microenvironment in LUAD: differences between Asians and Caucasians

Backgrounds

The characteristics of programmed cell death protein-1 (PD-L1) expression, tumor-infiltrating lymphocytes (TILs), and tumor microenvironment (TME) in lung adenocarcinoma (LUAD) patients are closely related to immunotherapy, and there are differences between Asians and Caucasians.

Methods

Acquire the transcriptome data of the Cancer Genome Atlas and Chinese LUAD patients. R software was used to analyze the differential expression of genes, prognosis, and gene function. Use CIBERSORT for TIL-related analysis and ESTIMATE for TME-related analysis.

Results

The expression of PD-L1 in tumor tissues of Caucasian LUAD patients was lower than that in normal tissues, while there was no significant difference in Asians. There was no statistical difference between PD-L1 expression and prognosis. The composition of TILs between Caucasian and Asian LUAD patients was quite different. There was no correlation between TILs and prognosis in Caucasians. However, the higher content of resting mast cells indicated a better prognosis in Asians. The Caucasian patients with higher immune and estimate scores had a better prognosis (p = 0.021, p = 0.025). However, the Asian patients with a higher estimate score had a worse prognosis (p = 0.024). The high expression of COL5A2 (p = 0.046, p = 0.027) and NOX4 (p = 0.020, p = 0.019) were both associated with the poor prognosis in Caucasians and Asians.

Conclusion

There are many differences in the characteristics of PD-L1 expression, TILs, and TME between Caucasian and Asian LUAD patients. This provides a certain hint for the selection of specific immunotherapy strategies separately for Caucasian and Asian LUAD patients.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13148-021-01221-3.

Signal pathways of melanoma and targeted therapy

Melanoma is the most lethal skin cancer that originates from the malignant transformation of melanocytes. Although melanoma has long been regarded as a cancerous malignancy with few therapeutic options, increased biological understanding and unprecedented innovations in therapies targeting mutated driver genes and immune checkpoints have substantially improved the prognosis of patients. However, the low response rate and inevitable occurrence of resistance to currently available targeted therapies have posed the obstacle in the path of melanoma management to obtain further amelioration. Therefore, it is necessary to understand the mechanisms underlying melanoma pathogenesis more comprehensively, which might lead to more substantial progress in therapeutic approaches and expand clinical options for melanoma therapy. In this review, we firstly make a brief introduction to melanoma epidemiology, clinical subtypes, risk factors, and current therapies. Then, the signal pathways orchestrating melanoma pathogenesis, including genetic mutations, key transcriptional regulators, epigenetic dysregulations, metabolic reprogramming, crucial metastasis-related signals, tumor-promoting inflammatory pathways, and pro-angiogenic factors, have been systemically reviewed and discussed. Subsequently, we outline current progresses in therapies targeting mutated driver genes and immune checkpoints, as well as the mechanisms underlying the treatment resistance. Finally, the prospects and challenges in the development of melanoma therapy, especially immunotherapy and related ongoing clinical trials, are summarized and discussed.

Impact of cancer metabolism on therapy resistance - Clinical implications

Despite an increasing arsenal of anticancer therapies, many patients continue to have poor outcomes due to the therapeutic failures and tumor relapses. Indeed, the clinical efficacy of anticancer therapies is markedly limited by intrinsic and/or acquired resistance mechanisms that can occur in any tumor type and with any treatment. Thus, there is an urgent clinical need to implement fundamental changes in the tumor treatment paradigm by the development of new experimental strategies that can help to predict the occurrence of clinical drug resistance and to identify alternative therapeutic options. Apart from mutation-driven resistance mechanisms, tumor microenvironment (TME) conditions generate an intratumoral phenotypic heterogeneity that supports disease progression and dismal outcomes. Tumor cell metabolism is a prototypical example of dynamic, heterogeneous, and adaptive phenotypic trait, resulting from the combination of intrinsic [(epi)genetic changes, tissue of origin and differentiation dependency] and extrinsic (oxygen and nutrient availability, metabolic interactions within the TME) factors, enabling cancer cells to survive, metastasize and develop resistance to anticancer therapies. In this review, we summarize the current knowledge regarding metabolism-based mechanisms conferring adaptive resistance to chemo-, radio-and immunotherapies as well as targeted therapies. Furthermore, we report the role of TME-mediated intratumoral metabolic heterogeneity in therapy resistance and how adaptations in amino acid, glucose, and lipid metabolism support the growth of therapy-resistant cancers and/or cellular subpopulations. We also report the intricate interplay between tumor signaling and metabolic pathways in cancer cells and discuss how manipulating key metabolic enzymes and/or providing dietary changes may help to eradicate relapse-sustaining cancer cells. Finally, in the current era of personalized medicine, we describe the strategies that may be applied to implement metabolic profiling for tumor imaging, biomarker identification, selection of tailored treatments and monitoring therapy response during the clinical management of cancer patients.

Application and prospects of single cell sequencing in tumors

Cancer is an intricate disease with inherent intra-tumor heterogeneity at the cellular level because of genetic changes and environmental differences. Cellular heterogeneity exists even within the same tumor type. Small deviations in a genome or transcriptome can lead to significant differences in function. Conventional bulk population sequencing, which produces admixed populations of cells, can only provide an average expression signal for one cell population, ignoring differences between individual cells. Important advances in sequencing have been made in recent years. Single cell sequencing starts in a single cell, thereby increasing our capability to characterize intratumor heterogeneity. This technology has been used to analyze genetic variation, specific metabolic activity, and evolutionary processes in tumors, which may help us understand tumor occurrence and development and improve our understanding of the tumor microenvironment. In addition, it provides a theoretical basis for the development of clinical treatments, especially for personalized medicine. In this article, we briefly introduce Single cell sequencing technology, summarize the application of Single cell sequencing to study the tumor microenvironment, as well as its therapeutic application in different clinical procedures.

Why may citrate sodium significantly increase the effectiveness of transarterial chemoembolization in hepatocellular carcinoma?

Hepatocellular carcinoma (HCC) represents the third cause of cancer death in men worldwide, and its increasing incidence can be explained by the increasing occurrence of non-alcoholic steatohepatitis (NASH). HCC prognosis is poor, as its 5-year overall survival is approximately 18 % and most cases are diagnosed at an inoperable advanced stage. Moreover, tumor sensitivity to conventional chemotherapeutics (particularly to cisplatin-based regimen), trans-arterial chemoembolization (cTACE), tyrosine kinase inhibitors, anti-angiogenic molecules and immune checkpoint inhibitors is limited. Oncogenic signaling pathways, such as HIF-1α and RAS/PI3K/AKT, may provoke drug resistance by enhancing the aerobic glycolysis ("Warburg effect") in cancer cells. Indeed, this metabolism, which promotes cancer cell development and aggressiveness, also induces extracellular acidity. In turn, this acidity promotes the protonation of drugs, hence abrogating their internalization, since they are most often weakly basic molecules. Consequently, targeting the Warburg effect in these cancer cells (which in turn would reduce the extracellular acidification) could be an effective strategy to increase the delivery of drugs into the tumor. Phosphofructokinase-1 (PFK1) and its activator PFK2 are the main regulators of glycolysis, and they also couple the enhancement of glycolysis to the activation of key signaling cascades and cell cycle progression. Therefore, targeting this "Gordian Knot" in HCC cells would be of crucial importance. Here, we suggest that this could be achieved by citrate administration at high concentration, because citrate is a physiologic inhibitor of PFK1 and PFK2. As shown in various in vitro studies, including HCC cell lines, administration of high concentrations of citrate inhibits PFK1 and PFK2 (and consequently glycolysis), decreases ATP production, counteracts HIF-1α and PI3K/AKT signaling, induces apoptosis, and sensitizes cells to cisplatin treatment. Administration of high concentrations of citrate in animal models (including Ras-driven tumours) has been shown to effectively inhibit cancer growth, reverse cell dedifferentiation, and neutralize intratumor acidity, without apparent toxicity in animal studies. Citrate may also induce a rapid secretion of pro-inflammatory cytokines by macrophages, and it could favour the destruction of cancer stem cells (CSCs) sustaining tumor recurrence. Consequently, this "citrate strategy" could improve the tumor sensitivity to current treatments of HCC by reducing the extracellular acidity, thus enhancing the delivery of chemotherapeutic drugs into the tumor. Therefore, we propose that this strategy should be explored in clinical trials, in particular to enhance cTACE effectiveness.

Immunotherapy in Non-Small Cell Lung Cancer With Actionable Mutations Other Than EGFR

While first line targeted therapies are the current standard of care treatment for non-small cell lung cancer (NSCLC) with actionable mutations, the cancer cells inevitably acquire resistance to these agents over time. Immune check-point inhibitors (ICIs) have improved the outcomes of metastatic NSCLC, however, its efficacy in those with targetable drivers is largely unknown. In this manuscript, we reviewed the published data on ICI therapies in NSCLC with ALK, ROS1, BRAF, c-MET, RET, NTRK, KRAS, and HER2 (ERBB2) alterations. We found that the objective response rates (ORRs) associated with ICI treatments in lung cancers harboring the BRAF (0-54%), c-MET (12-49%), and KRAS (18.7-66.7%) alterations were comparable to non-mutant NSCLC, whereas the ORRs in RET fusion NSCLC (less than10% in all studies but one) and ALK fusion NSCLC (0%) were relatively low. The ORRs reported in small numbers of patients and studies of ROS1 fusion, NTRK fusion, and HER 2 mutant NSCLC were 0-17%, 50% and 7-23%, respectively, making the efficacy of ICIs in these groups of patients less clear. In most studies, no significant correlation between treatment outcome and PD-L1 expression or tumor mutation burden (TMB) was identified, and how to select patients with NSCLC harboring actionable mutations who will likely benefit from ICI treatment remains unknown.

Hypoxia as a driver of resistance to immunotherapy

Hypoxia, a hallmark of solid tumors, determines the selection of invasive and aggressive malignant clones displaying resistance to radiotherapy, conventional chemotherapy or targeted therapy. The recent introduction of immunotherapy, based on immune checkpoint inhibitors (ICPIs) and chimeric antigen receptor (CAR) T-cells, has markedly transformed the prognosis in some tumors but also revealed the existence of intrinsic or acquired drug resistance. In the current review we highlight hypoxia as a culprit of immunotherapy failure. Indeed, multiple metabolic cross talks between tumor and stromal cells determine the prevalence of immunosuppressive populations within the hypoxic tumor microenvironment and confer upon tumor cells resistance to ICPIs and CAR T-cells. Notably, hypoxia-triggered angiogenesis causes immunosuppression, adding another piece to the puzzle of hypoxia-induced immunoresistance. If these factors concurrently contribute to the resistance to immunotherapy, they also unveil an unexpected Achille's heel of hypoxic tumors, providing the basis for innovative combination therapies that may rescue the efficacy of ICPIs and CAR T-cells. Although these treatments reveal both a bright side and a dark side in terms of efficacy and safety in clinical trials, they represent the future solution to enhance the efficacy of immunotherapy against hypoxic and therapy-resistant solid tumors.

Targeting bone microenvironments for treatment and early detection of cancer bone metastatic niches

Bone tissues are the main metastatic sites of many cancers, and bone metastasis is an important cause of death. When bone metastasis occurs, dynamic interactions between tumor cells and bone tissues promote changes in the tumor-bone microenvironments that are conducive to tumor growth and progression, which also promote several related diseases, including pathological fracture, bone pain, and hypercalcemia. Accordingly, it has obvious clinical benefits for improving the cure rate and reducing the occurrence of related diseases through targeting bone microenvironments for the treatment and early detection of cancer bone metastasis niches. In this review, we briefly analyzed the relationship between bone microstructures and tumor metastasis, as well as microenvironmental changes in osteoblasts, osteoclasts, immune cells, and extracellular and bone matrixes caused when metastatic tumor cells colonize bones. We also discuss novel designs in nanodrugs for inhibiting tumor proliferation and migration through targeting to tumor bone metastases and abnormal bone-microenvironment components. In addition, related researches on the early detection of bone and multi-organ metastases by nanoprobes are also introduced. And we look forward to provide some useful proposals and enlightenments on nanotechnology-based drug delivery and probes for the treatment and early detection of bone metastasis.

ACKR4 in Tumor Cells Regulates Dendritic Cell Migration to Tumor-Draining Lymph Nodes and T-Cell Priming

Colorectal cancer (CRC) is one of the most common malignancies in both morbidity and mortality. Immune checkpoint blockade (ICB) treatments have been successful in a portion of mismatch repair-deficient (dMMR) CRC patients but have failed in mismatch repair-proficient (pMMR) CRC patients. Atypical Chemokine Receptor 4 (ACKR4) is implicated in regulating dendritic cell (DC) migration. However, the roles of ACKR4 in CRC development and anti-tumor immunoregulation are not known. By analyzing human CRC tissues, transgenic animals, and genetically modified CRC cells lines, our study revealed an important function of ACKR4 in maintaining CRC immune response. Loss of ACKR4 in CRC is associated with poor immune infiltration in the tumor microenvironment. More importantly, loss of ACKR4 in CRC tumor cells, rather than stromal cells, restrains the DC migration and antigen presentation to the tumor-draining lymph nodes (TdLNs). Moreover, tumors with ACKR4 knockdown become less sensitive to immune checkpoint blockade. Finally, we identified that microRNA miR-552 negatively regulates ACKR4 expression in human CRC. Taken together, our studies identified a novel and crucial mechanism for the maintenance of the DC-mediated T-cell priming in the TdLNs. These new findings demonstrate a novel mechanism leading to immunosuppression and ICB treatment resistance in CRC.

Abscopal Effect and Drug-Induced Xenogenization: A Strategic Alliance in Cancer Treatment?

The current state of cancer treatment is still far from being satisfactory considering the strong impairment of patients' quality of life and the high lethality of malignant diseases. Therefore, it is critical for innovative approaches to be tested in the near future. In view of the crucial role that is played by tumor immunity, the present review provides essential information on the immune-mediated effects potentially generated by the interplay between ionizing radiation and cytotoxic antitumor agents when interacting with target malignant cells. Therefore, the radiation-dependent abscopal effect (i.e., a biological effect of ionizing radiation that occurs outside the irradiated field), the influence of cancer chemotherapy on the antigenic pattern of target neoplastic cells, and the immunogenic cell death (ICD) caused by anticancer agents are the main topics of this presentation. It is widely accepted that tumor immunity plays a fundamental role in generating an abscopal effect and that anticancer drugs can profoundly influence not only the host immune responses, but also the immunogenic pattern of malignant cells. Remarkably, several anticancer drugs impact both the abscopal effect and ICD. In addition, certain classes of anticancer agents are able to amplify already expressed tumor-associated antigens (TAA). More importantly, other drugs, especially triazenes, induce the appearance of new tumor neoantigens (TNA), a phenomenon that we termed drug-induced xenogenization (DIX). The adoption of the abscopal effect is proposed as a potential therapeutic modality when properly applied concomitantly with drug-induced increase in tumor cell immunogenicity and ICD. Although little to no preclinical or clinical studies are presently available on this subject, we discuss this issue in terms of potential mechanisms and therapeutic benefits. Upcoming investigations are aimed at evaluating how chemical anticancer drugs, radiation, and immunotherapies are interacting and cooperate in evoking the abscopal effect, tumor xenogenization and ICD, paving the way for new and possibly successful approaches in cancer therapy.

Contribution of Ezrin on the Cell Surface Plasma Membrane Localization of Programmed Cell Death Ligand-1 in Human Choriocarcinoma JEG-3 Cells

Immune checkpoint blockade (ICB) antibodies targeting programmed cell death ligand-1 (PD-L1) and programmed cell death-1 (PD-1) have improved survival in patients with conventional single agent chemotherapy-resistant gestational trophoblastic neoplasia (GTN). However, many patients are resistant to ICB therapy, the mechanisms of which are poorly understood. Unraveling the regulatory mechanism for PD-L1 expression may provide a new strategy to improve ICB therapy in patients with GTN. Here, we investigated whether the ezrin/radixin/moesin (ERM) family, i.e., a group of scaffold proteins that crosslink actin cytoskeletons with several plasma membrane proteins, plays a role in the regulation of PD-L1 expression using JEG-3 cells, a representative human choriocarcinoma cell line. Our results demonstrate mRNA and protein expressions of ezrin, radixin, and PD-L1, as well as their colocalization in the plasma membrane. Intriguingly, immunoprecipitation experiments revealed that PD-L1 interacted with both ezrin and radixin and the actin cytoskeleton. Moreover, gene silencing of ezrin but not radixin strongly diminished the cell surface expression of PD-L1 without altering the mRNA level. These results indicate that ezrin may contribute to the cell surface localization of PD-L1 as a scaffold protein in JEG-3 cells, highlighting a potential therapeutic target to improve the current ICB therapy in GTN.

Ezrin Modulates the Cell Surface Expression of Programmed Cell Death Ligand-1 in Human Cervical Adenocarcinoma Cells

Cancer cells employ programmed cell death ligand-1 (PD-L1), an immune checkpoint protein that binds to programmed cell death-1 (PD-1) and is highly expressed in various cancers, including cervical carcinoma, to abolish T-cell-mediated immunosurveillance. Despite a key role of PD-L1 in various cancer cell types, the regulatory mechanism for PD-L1 expression is largely unknown. Understanding this mechanism could provide a novel strategy for cervical cancer therapy. Here, we investigated the influence of ezrin/radixin/moesin (ERM) family scaffold proteins, crosslinking the actin cytoskeleton and certain plasma membrane proteins, on the expression of PD-L1 in HeLa cells. Our results showed that all proteins were expressed at mRNA and protein levels and that all ERM proteins were highly colocalized with PD-L1 in the plasma membrane. Interestingly, immunoprecipitation assay results demonstrated that PD-L1 interacted with ERM as well as actin cytoskeleton proteins. Furthermore, gene silencing of ezrin, but not radixin and moesin, remarkably decreased the protein expression of PD-L1 without affecting its mRNA expression. In conclusion, ezrin may function as a scaffold protein for PD-L1; regulate PD-L1 protein expression, possibly via post-translational modification in HeLa cells; and serve as a potential therapeutic target for cervical cancer, improving the current immune checkpoint blockade therapy.

Role of Phytochemicals in Cancer Chemoprevention: Insights

Cancer is a condition where the body cells multiply in an uncontrollable manner. Chemoprevention of cancer is a broad term that describes the involvement of external agents to slow down or suppress cancer growth. Synthetic and natural compounds are found useful in cancer chemoprevention. The occurrence of global cancer type varies, depending on many factors such as environmental, lifestyle, genetic etc. Cancer is often preventable in developed countries with advanced treatment modalities, whereas it is a painful death sentence in developing and low-income countries due to the lack of modern therapies and awareness. One best practice to identify cancer control measures is to study the origin and risk factors associated with common types. Based on these factors and the health status of patients, stage, and severity of cancer, type of treatment is decided. Even though there are well-established therapies, cancer still stands as one of the major causes of death and a public health burden globally. Research shows that most cancers can be prevented, treated, or the incidence can be delayed. Phytochemicals from various medicinal plants were reported to reduce various risk factors associated with different types of cancer through their chemopreventive role. This review highlights the role of bioactive compounds or natural products from plants in the chemoprevention of cancer. There are many plant based dietary factors involved in the chemoprevention process. The review discusses the process of carcinogenesis and chemoprevention using plants and phytocompounds, with special reference to five major chemopreventive phytocompounds. The article also summarizes the important chemopreventive mechanisms and signaling molecules involved in the process. Since the role of antioxidants in chemoprevention is inevitable, an insight into plant-based antioxidant compounds that fight against this dreadful disease at various stages of carcinogenesis and disease progression is discussed. This will fill the research gap in search of chemopreventive natural compounds and encourage scientists in clinical trials of anticancer agents from plants.

Resistance to immunotherapy in human malignancies: Mechanisms, research progresses, challenges, and opportunities

Despite remarkable advances in different types of cancer therapies, an effective therapeutic strategy is still a major and significant challenge. One of the most promising approaches in this regard is immunotherapy, which takes advantage of the patients' immune system; however, the many mechanisms that cancerous cells harbor to extend their survival make it impossible to gain perfect eradication of tumors. The response rate to cancer immunotherapies, especially checkpoint inhibitors and adoptive T cell therapy, substantially differs in various cancer types with the highest rates in advanced melanoma and non-small cell lung cancer. Indeed, the lack of response in many tumors indicates primary resistance that can originate from either tumor cells (intrinsic) or tumor microenvironment (extrinsic). On the other hand, some tumors show an initial response to immunotherapy followed by relapse in few months (acquired resistance). Understanding the underlying molecular mechanisms of immunotherapy resistance makes it possible to develop effective strategies to overcome this hurdle and boost therapy outcomes. In this review, we take a look at immunotherapy strategies and go through a number of primary and acquired resistance mechanisms. Also, we present various ongoing methods to overcoming resistance and introduce some promising fields to improve the outcome of immunotherapy in patients affected with cancer.

CXCL2-mediated ATR/CHK1 signaling pathway and platinum resistance in epithelial ovarian cancer

Tumor microenvironment and chemokines play a significant role in cancer chemoresistance. This study was designed to reveal the important role of CXCL2 in platinum resistance in epithelial ovarian cancer (EOC). Differently expressed (DE) genes were screen out based on analysis of GSE114206 dataset in GEO database. The expression of DE chemokines was further validated in platinum- resistant and sensitive EOC. Cell viability assay and cell apoptosis assay were performed to explore the roles of CXCL2 in EOC. Cell stemness characteristics and the signaling pathway regulated by CXCL2 were also investigated in this study. As the results showed, CXCL2 was identified up-regulated in platinum-resistant EOC. The functional assays showed overexpressing CXCL2 or co-culturing with recombinant human CXCL2 promoted cell resistance to cisplatin. Conversely, knocking down CXCL2 or co-culturing with neutralizing antibody to CXCL2 increased cell response to cisplatin. CXCL2 overexpressing maintained cell stemness and activated ATR/CHK1 signaling pathway in EOC. Moreover, we further demonstrated that CXCL2-mediated resistance to cisplatin could be saved by SB225002, the inhibitor of CXCL2 receptor, as well as be rescued by SAR-020106, the inhibitor of ATR/CHK1 signaling pathway. This study identified a CXCL2-mediated mechanism in EOC platinum resistance. Our findings provided a novel target for chemoresistance prevention in EOC.

Role of Ezrin/Radixin/Moesin in the Surface Localization of Programmed Cell Death Ligand-1 in Human Colon Adenocarcinoma LS180 Cells

Programmed cell death ligand-1 (PD-L1), an immune checkpoint protein highly expressed on the cell surface in various cancer cell types, binds to programmed cell death-1 (PD-1), leading to T-cell dysfunction and tumor survival. Despite clinical successes of PD-1/PD-L1 blockade therapies, patients with colorectal cancer (CRC) receive little benefit because most cases respond poorly. Because high PD-L1 expression is associated with immune evasion and poor prognosis in CRC patients, identifying potential modulators for the plasma membrane localization of PD-L1 may represent a novel therapeutic strategy for enhancing the efficacy of PD-1/PD-L1 blockade therapies. Here, we investigated whether PD-L1 expression in human colorectal adenocarcinoma cells (LS180) is affected by ezrin/radixin/moesin (ERM), functioning as scaffold proteins that crosslink plasma membrane proteins with the actin cytoskeleton. We observed colocalization of PD-L1 with all three ERM proteins in the plasma membrane and detected interactions involving PD-L1, the three ERM proteins, and the actin cytoskeleton. Furthermore, gene silencing of ezrin and radixin, but not of moesin, substantially decreased the expression of PD-L1 on the cell surface without affecting its mRNA level. Thus, in LS180 cells, ezrin and radixin may function as scaffold proteins mediating the plasma membrane localization of PD-L1, possibly by post-translational modification.

Mesenchymal Stem/Stromal Cells as a Vehicle for Cytokine Delivery: An Emerging Approach for Tumor Immunotherapy

Pro-inflammatory cytokines can effectively be used for tumor immunotherapy, affecting every step of the tumor immunity cycle. Thereby, they can restore antigen priming, improve the effector immune cell frequencies in the tumor microenvironment (TME), and eventually strengthen their cytolytic function. A renewed interest in the anticancer competencies of cytokines has resulted in a substantial promotion in the number of trials to address the safety and efficacy of cytokine-based therapeutic options. However, low response rate along with the high toxicity associated with high-dose cytokine for reaching desired therapeutic outcomes negatively affect their clinical utility. Recently, mesenchymal stem/stromal cells (MSCs) due to their pronounced tropism to tumors and also lower immunogenicity have become a promising vehicle for cytokine delivery for human malignancies. MSC-based delivery of the cytokine can lead to the more effective immune cell-induced antitumor response and provide sustained release of target cytokines, as widely evidenced in a myriad of xenograft models. In the current review, we offer a summary of the novel trends in cytokine immunotherapy using MSCs as a potent and encouraging carrier for antitumor cytokines, focusing on the last two decades' animal reports.

Metal- and metalloid-based compounds to target and reverse cancer multidrug resistance

Drug resistance remains the major cause of cancer treatment failure especially at the late stage of the disease. However, based on their versatile chemistry, metal and metalloid compounds offer the possibility to design fine-tuned drugs to circumvent and even specifically target drug-resistant cancer cells. Based on the paramount importance of platinum drugs in the clinics, two main areas of drug resistance reversal strategies exist: overcoming resistance to platinum drugs as well as multidrug resistance based on ABC efflux pumps. The current review provides an overview of both aspects of drug design and discusses the open questions in the field. The areas of drug resistance covered in this article involve: 1) Altered expression of proteins involved in metal uptake, efflux or intracellular distribution, 2) Enhanced drug efflux via ABC transporters, 3) Altered metabolism in drug-resistant cancer cells, 4) Altered thiol or redox homeostasis, 5) Altered DNA damage recognition and enhanced DNA damage repair, 6) Impaired induction of apoptosis and 7) Altered interaction with the immune system. This review represents the first collection of metal (including platinum, ruthenium, iridium, gold, and copper) and metalloid drugs (e.g. arsenic and selenium) which demonstrated drug resistance reversal activity. A special focus is on compounds characterized by collateral sensitivity of ABC transporter-overexpressing cancer cells. Through this approach, we wish to draw the attention to open research questions in the field. Future investigations are warranted to obtain more insights into the mechanisms of action of the most potent compounds which target specific modalities of drug resistance.

CELF2 is a candidate prognostic and immunotherapy biomarker in triple-negative breast cancer and lung squamous cell carcinoma: A pan-cancer analysis

CUGBP Elav‐like family member 2(CELF2) plays crucial roles in the development and activation of T cell. However, the impacts of CELF2 on tumour‐infiltrating immune cells (TIICs) and clinical outcomes of tumours remain unclear. In this study, we found that elevated CELF2 expression was markedly correlated with prolonged survival in multiple tumours, particularly in breast and lung cancers. Notably, CELF2 only impacted the prognosis of triple‐negative breast cancer (TNBC) with lymph node metastasis. Further investigation showed CELF2 expression was positively correlated with the infiltration abundance of dendritic cells (DCs), CD8+ T cells and neutrophils in breast invasive carcinoma (BRCA) and DCs in lung squamous cell carcinoma (LUSC). CELF2 also had strong correlations with markers of diverse TIICs such as T cells, tumour‐associated macrophages and DCs in BRCA and LUSC. Importantly, CELF2 was significantly associated with plenty of immune checkpoint molecules (ICMs) and outperformed five prevalent biomarkers including PD‐1, PD‐L1, CTLA‐4, CD8 and tumour mutation burden in predicting immunotherapeutic responses. Immunohistochemistry also revealed lower protein levels of CELF2 in TNBC and LUSC compared to normal tissues, and patients with high expression showed significantly prolonged prognosis. In conclusion, we demonstrated that increased CELF2 expression was closely related to better prognosis and superior TIIC infiltration and ICM expression, particularly in BRCA and LUSC. CELF2 also performed well in evaluating the immunotherapeutic efficacy, suggesting CELF2 might be a promising biomarker.

Myeloid-Derived Suppressor Cells: Implications in the Resistance of Malignant Tumors to T Cell-Based Immunotherapy

T lymphocytes function as major players in antigen-mediated cytotoxicity and have become powerful tools for exploiting the immune system in tumor elimination. Several types of T cell-based immunotherapies have been prescribed to cancer patients with durable immunological response. Such strategies include immune checkpoint inhibitors, adoptive T cell therapy, cancer vaccines, oncolytic virus, and modulatory cytokines. However, the majority of cancer patients still failed to take the advantage of these kinds of treatments. Currently, extensive attempts are being made to uncover the potential mechanism of immunotherapy resistance, and myeloid-derived suppressor cells (MDSCs) have been identified as one of vital interpretable factors. Here, we discuss the immunosuppressive mechanism of MDSCs and their contributions to failures of T cell-based immunotherapy. Additionally, we summarize combination therapies to ameliorate the efficacy of T cell-based immunotherapy.

Genomic Landscape of Chinese Clear Cell Renal Cell Carcinoma Patients With Venous Tumor Thrombus Identifies Chromosome 9 and 14 Deletions and Related Immunosuppressive Microenvironment

BACKGROUND

Clear cell renal cell carcinoma (ccRCC) with venous tumor thrombus (VTT) is associated with a poor clinical outcome. Although several studies have examined the genomic features of ccRCC, the genetic profile of VTT along with its matched primary tumor has not been fully elucidated.

MATERIALS AND METHODS

Samples of VTT tissues and matched primary tumor tissues from ccRCC patients (n = 25), as well as primary tumor tissues from patients without VTT (n = 25) were collected and analyzed using whole-exome sequencing. Four additional ccRCC patients who were unfit for surgery were treated with an anti-programmed death receptor-1 (PD-1) monoclonal antibody (Toripalimab, 240 mg, Q3W, IV).

RESULTS

By comparing the primary kidney tumors from ccRCC patients with or without VTT, a relatively higher prevalence of BAP1 and KDM5C alterations were found in ccRCC patients with VTT, and these alterations were associated with worse overall survival in the kidney renal clear cell carcinoma (KIRC) database. Based on subclone analysis, VTT was predicted to primarily originate directly from the primary renal mass. A significantly higher prevalence of CELSR2 and TET2 alterations were identified in the VTTs compared with the matched primary tumors. An increased prevalence of DNA damage repair genes, especially those involved in homologous recombination repair and non-homologous end joining, was found in ccRCC patients with VTT. Notably, VTT was characterized by the increase incidence of copy number loss in the whole exome (p < 0.05), particularly in the chromosome 9 and 14 regions. Deletion of chromosome 9 and 14 was associated with worse survival, unfavorable clinical features, and the presence of an immunosuppressive microenvironment, which was characterized by higher infiltration of regulatory T cells, follicular helper T cells, and resting mast cells, but lower counts of resting CD4 memory T cells and CD8 positive T cells. A significantly lower count of CD4+ and CD8+ tumor-infiltrated lymphocytes was identified in the VTT samples comparing with matched primary tumor. Of note, three out of the four ccRCC patients with VTT in our cohort who were treated with the anti-PD-1 therapy exhibited remarkable remission in the renal mass but no notable shrinkage in the VTT mass.

CONCLUSION

Our study revealed the genetic profile of Chinese ccRCC patients with VTT, and identified multiple features associated with known poor outcomes, including gene alterations and copy number loss. The deletions in chromosomes 9 and 14, and the associated immunosuppressive microenvironment may indicate limited sensitivity to anti-PD-1/PD-L1 monotherapy in VTT.

The Emergence of Immune-checkpoint Inhibitors in Colorectal Cancer Therapy

Immunotherapy has revolutionized the treatment landscape in a number of solid tumors. In colorectal cancer, evidence suggests that microsatellite high (MSI-H) tumors are the most responsive to immune checkpoint blockade due to increased neo-antigen load and a favorable tumor microenvironment. Indeed, Pembrolizumab now represents a first-line option in such patients. However, MSI-H tumors represent the minority and a proportion of patients' progress despite initially responding. Trials are investigating different immunotherapy combinatorial strategies to enhance immune response in less immunogenic colorectal tumors. Such strategies include dual immune checkpoint blockade, combining immune checkpoint inhibitors with other treatment modalities such as radiotherapy, chemotherapy or other biological or targeted agents. Moreover, there is an increasing drive to identify biomarkers to better select patients most likely to respond to immunotherapy and understand intrinsic and acquired resistance mechanisms. Apart from MSI-H tumors, there is a strong rationale to suggest that tumors with alterations in DNA polymerase epsilon and DNA polymerase delta are also likely to respond to immunotherapy and trials in this subpopulation are underway. Other strategies such as priming O6-methylguanineDNA methyltransferase silenced tumors with alkylating agents to make them receptive to immune checkpoint blockade are also being investigated. Here we discuss different colorectal subpopulations together with their likelihood of response to immune checkpoint blockade and strategies to overcome barriers to a successful clinical outcome. We summarize evidence from published clinical trials and provide an overview of trials in progress whilst discussing newer immunotherapy strategies such as adoptive cell therapies and cancer vaccines.

Overexpression of PTPRN Promotes Metastasis of Lung Adenocarcinoma and Suppresses NK Cell Cytotoxicity

Background

Lung adenocarcinoma (LUAD) is the most common diagnostic histologic subtype of non-small cell lung cancer, but the role of receptor-type tyrosine-protein phosphatase-like N (PTPRN) in LUAD has not been studied.

Methods

We conducted a bioinformatic analysis to identify the expression of PTPRN on LUAD data from the Cancer Genome Atlas (TCGA) and the relationship between PTPRN and overall survival of LUAD patients. The effects of PTPRN on the migration ability of LUAD cells and the underlying mechanisms were investigated by in vitro and in vivo assays (i.e., wound healing assay, transwell assay, western blotting, xenograft model, and immunohistochemistry). Gene-set enrichment analysis and computational resource were used to analyze the correlation between PTPRN and different tumor-infiltrating immune cells (TIICs). Lactate dehydrogenase assay and Enzyme-linked immunosorbent assay were conducted to examine natural killer (NK) cell cytotoxicity.

Results

In our study, we found that PTPRN was up-regulated in LUAD and related to metastasis of LUAD patients. Besides, PTPRN was correlated with poor prognosis in the TCGA-LUAD dataset. PTPRN overexpression promoted LUAD cell migration and the expression of EMT markers by influencing MEK/ERK and PI3K/AKT signaling. Moreover, PTPRN expression was significantly associated with TIICs, especially NK cells. A549 and H1299 cells overexpressed PTPRN inhibited NK cell cytotoxicity.

Conclusion

Taken together, these findings demonstrated that PTPRN might be a potential and novel therapeutic target modulating antitumor immune response in treatment of LUAD.