Metastasis is regulated via microRNA-200/ZEB1 axis control of tumour cell PD-L1 expression and intratumoral immunosuppression

MiRNA-based model for predicting the TMB level in colon adenocarcinoma based on a LASSO logistic regression method

Some patients with advanced colon adenocarcinoma (COAD) are not sensitive to radiotherapy and chemotherapy, and as such, immunotherapy has become the most popular option for these patients. However, different patients respond differently to immunotherapy. Tumor mutational burden (TMB) has been used as a predictor of the response of advanced COAD patients to immunotherapy. A high TMB typically indicates that the patient's immune system will respond well to immunotherapy. In addition, while microRNAs (miRNA) have been shown to play an important role in treatment responses associated with the immune system, the relationship between miRNA expression levels and TMB has not been clarified in COAD.We downloaded miRNA data and mutational files of COAD from the Cancer Genome Atlas database. Differentially expressed miRNAs were screened in the training group, and miRNAs used to construct the model were further identified using the LASSO logistic regression method. After building the miRNA-based model, we explored the correlation between the model and TMB. The model was verified by a receiver operating characteristic curve, and the correlation between it and 3 widely used immune checkpoints (programmed death receptor-1, programmed death-ligand 1, and cytotoxic T-lymphocyte associated protein-4) was explored. Functional enrichment analysis of the selected miRNAs was performed, and these respective miRNA target genes were predicted using online tools.Our results showed that a total of 32 differentially expressed miRNAs were used in the construction of the model. The accuracies of the models of the 2 datasets (training and test sets) were 0.987 and 0.934, respectively. Correlation analysis showed that the correlation of the model with programmed death-ligand 1 and cytotoxic T-lymphocyte associated protein-4, as well as TMB, was high, but there was no correlation with programmed death receptor-1. The results of functional enrichment analysis indicated that these 32 miRNAs were involved in many immune-related biological processes and tumor-related pathways.Therefore, this study demonstrated that differentially expressed miRNAs can be used to predict the TMB level, which can help identify advanced COAD patients who will respond well to immunotherapy. The miRNA-based model may be used as a tool to predict the TMB level in patients with advanced COAD.

MicroRNA-200c restoration reveals a cytokine profile to enhance M1 macrophage polarization in breast cancer

Many immune suppressive mechanisms utilized by triple negative breast cancer (TNBC) are regulated by oncogenic epithelial-to-mesenchymal transition (EMT). How TNBC EMT impacts innate immune cells is not fully understood. To determine how TNBC suppresses antitumor macrophages, we used microRNA-200c (miR-200c), a powerful repressor of EMT, to drive mesenchymal-like mouse mammary carcinoma and human TNBC cells toward a more epithelial state. MiR-200c restoration significantly decreased growth of mouse mammary carcinoma Met-1 cells in culture and in vivo. Cytokine profiling of Met-1 and human BT549 cells revealed that miR-200c upregulated cytokines, such as granulocyte-macrophage colony-stimulating factor (GM-CSF), promoted M1 antitumor macrophage polarization. Cytokines upregulated by miR-200c correlated with an epithelial gene signature and M1 macrophage polarization in BC patients and predicted a more favorable overall survival for TNBC patients. Our findings demonstrate that immunogenic cytokines (e.g., GM-CSF) are suppressed in aggressive TNBC, warranting further investigation of cytokine-based therapies to limit disease recurrence.

Epithelial to Mesenchymal Transition History: From Embryonic Development to Cancers

Epithelial to mesenchymal transition (EMT) is a process that allows epithelial cells to progressively acquire a reversible mesenchymal phenotype. Here, we recount the main events in the history of EMT. EMT was first studied during embryonic development. Nowadays, it is an important field in cancer research, studied all around the world by more and more scientists, because it was shown that EMT is involved in cancer aggressiveness in many different ways. The main features of EMT's involvement in embryonic development, fibrosis and cancers are briefly reviewed here.

Programmed Death-Ligand 1 as a Regulator of Tumor Progression and Metastasis

Programmed cell death protein 1 (PD-1)/programmed death-ligand 1 (PD-L1) immune checkpoint has long been implicated in modeling antitumor immunity; PD-1/PD-L1 axis inhibitors exert their antitumor effects by relieving PD-L1-mediated suppression on tumor-infiltrating T lymphocytes. However, recent studies have unveiled a distinct, tumor-intrinsic, potential role for PD-L1. In this review, we focus on tumor-intrinsic PD-L1 signaling and delve into preclinical evidence linking PD-L1 protein expression with features of epithelial-to-mesenchymal transition program, cancer stemness and known oncogenic pathways. We further summarize data from studies supporting the prognostic significance of PD-L1 in different tumor types. We show that PD-L1 may indeed have oncogenic potential and act as a regulator of tumor progression and metastasis.

Cancer drug resistance induced by EMT: novel therapeutic strategies

Over the last decade, important clinical benefits have been achieved in cancer patients by using drug-targeting strategies. Nevertheless, drug resistance is still a major problem in most cancer therapies. Epithelial-mesenchymal plasticity (EMP) and tumour microenvironment have been described as limiting factors for effective treatment in many cancer types. Moreover, epithelial-to-mesenchymal transition (EMT) has also been associated with therapy resistance in many different preclinical models, although limited evidence has been obtained from clinical studies and clinical samples. In this review, we particularly deepen into the mechanisms of which intermediate epithelial/mesenchymal (E/M) states and its interconnection to microenvironment influence therapy resistance. We also describe how the use of bioinformatics and pharmacogenomics will help to figure out the biological impact of the EMT on drug resistance and to develop novel pharmacological approaches in the future.

MicroRNAs: immune modulators in cancer immunotherapy

MicroRNA (miRNA) is a class of endogenous small non-coding RNA of 18–25 nucleotides and plays regulatory roles in both physiological and pathological processes. Emerging evidence support that miRNAs function as immune modulators in tumors. MiRNAs as tumor suppressors or oncogenes are also found to be able to modulate anti-tumor immunity or link the crosstalk between tumor cells and immune cells surrounding. Based on the specific regulating function, miRNAs can be used as predictive, prognostic biomarkers, and therapeutic targets in immunotherapy. Here, we review new findings about the role of miRNAs in modulating immune responses, as well as discuss mechanisms underlying their dysregulation, and their clinical potentials as indicators of tumor prognosis or to sensitize cancer immunotherapy.

MicroRNAs as Modulators of Tumor Metabolism, Microenvironment, and Immune Response in Hepatocellular Carcinoma

Hepatocellular carcinoma (HCC) is the second leading cause of cancer-related mortality. Molecular heterogeneity and absence of biomarkers helping patient allocation to the best therapeutic option contribute to poor prognosis in advanced stages. MicroRNAs’ (miRNAs) deregulated expression contributes to tumor development and progression and influences drug resistance in HCC. Accordingly, miRNAs have been extensively investigated as both biomarkers and therapeutic targets. The diagnostic and prognostic roles of circulating miRNAs have been ascertained, though with some inconsistencies across studies. From a therapeutic perspective, miRNA-based approaches demonstrated safety profiles and antitumor efficacy in HCC animal models. Nevertheless, caution should be used when transferring preclinical findings to the clinic, due to possible molecular inconsistency between animal models and the heterogeneous patterns of human diseases. A wealth of information is offered by preclinical studies exploring the mechanisms driving miRNAs’ aberrant expression, the molecular cascades triggered by miRNAs and the corresponding phenotypic changes. Ex-vivo analyses confirmed these results, further shedding light on the intricacy of the human disease often overcoming pre-clinical models. This complexity seems to be ascribed to the intrinsic heterogeneity of HCC, to different risk factors driving its development, as well as to changes across stages and previous treatments. Preliminary findings suggest that miRNAs associated with specific risk factors might be more informative in defined patients’ subgroups. The first issue to be considered when trying to envisage a possible translational perspective is the molecular context that often drives different miRNA functions, as clearly evidenced by “dual” miRNAs. Concerning the possible roles of miRNAs as biomarkers and therapeutic targets, we will focus on miRNAs’ involvement in metabolic pathways and in the modulation of tumor microenvironment, to support their exploitation in defined contexts.

Th17 cells contribute to combination MEK inhibitor and anti-PD-L1 therapy resistance in KRAS/p53 mutant lung cancers

Understanding resistance mechanisms to targeted therapies and immune checkpoint blockade in mutant KRAS lung cancers is critical to developing novel combination therapies and improving patient survival. Here, we show that MEK inhibition enhanced PD-L1 expression while PD-L1 blockade upregulated MAPK signaling in mutant KRAS lung tumors. Combined MEK inhibition with anti-PD-L1 synergistically reduced lung tumor growth and metastasis, but tumors eventually developed resistance to sustained combinatorial therapy. Multi-platform profiling revealed that resistant lung tumors have increased infiltration of Th17 cells, which secrete IL-17 and IL-22 cytokines to promote lung cancer cell invasiveness and MEK inhibitor resistance. Antibody depletion of IL-17A in combination with MEK inhibition and PD-L1 blockade markedly reduced therapy-resistance in vivo. Clinically, increased expression of Th17-associated genes in patients treated with PD-1 blockade predicted poorer overall survival and response in melanoma and predicated poorer response to anti-PD1 in NSCLC patients. Here we show a triple combinatorial therapeutic strategy to overcome resistance to combined MEK inhibitor and PD-L1 blockade.

The regulation of immune checkpoints by the hypoxic tumor microenvironment

The tumor microenvironment (TME) influences the occurrence and progression of tumors, and hypoxia is an important characteristic of the TME. The expression of programmed death 1 (PD1)/programmed death-ligand 1 (PDL1), cytotoxic T-lymphocyte-associated antigen 4 (CTLA4), and other immune checkpoints in hypoxic malignant tumors is often significantly increased, and is associated with poor prognosis. The application of immune checkpoint inhibitors (ICIs) for treating lung cancer, urothelial carcinoma, and gynecological tumors has achieved encouraging efficacy; however, the rate of efficacy of ICI single-drug treatment is only about 20%. In the present review, we discuss the possible mechanisms by which the hypoxic TME regulates immune checkpoints. By activating hypoxia-inducible factor-1α (HIF-1α), regulating the adenosine (Ado)-A2aR pathway, regulating the glycolytic pathway, and driving epithelial-mesenchymal transition (EMT) and other biological pathways, hypoxia regulates the expression levels of CTLA4, PD1, PDL1, CD47, lymphocyte activation gene 3 (LAG3), T-cell immunoglobulin and mucin domain 3 (TIM3), and other immune checkpoints, which interfere with the immune effector cell anti-tumor response and provide convenient conditions for tumors to escape immune surveillance. The combination of HIF-1α inhibitors, Ado-inhibiting tumor immune microenvironment regulatory drugs, and other drugs with ICIs has good efficacy in both preclinical studies and phase I-II clinical studies. Exploring the effects of TME hypoxia on the expression of immune checkpoints and the function of infiltrating immune cells has greatly clarified the relationship between the hypoxic TME and immune escape, which is of great significance for the development of new drugs and the search for predictive markers of the efficacy of immunotherapy for treating malignant tumors. In the future, combination therapy with hypoxia pathway inhibitors and ICIs may be an effective anti-tumor treatment strategy.

miRNA-Based Therapeutics in Breast Cancer: A Systematic Review

Background

Breast cancer (BC) is the most common cancer in females and despite advances in treatment, it represents the leading cause of cancer mortality in women worldwide. Conventional therapeutic modalities have significantly improved the management of BC patients, but subtype heterogeneity, drug resistance, and tumor relapse remain the major factors to hamper the effectiveness of therapy for BC. In this scenario, miRNA(miR)-based therapeutics offer a very attractive area of study. However, the use of miR-based therapeutics for BC treatment still represents an underdeveloped topic. Therefore, this systematic review aims at summarizing current knowledge on promising miR-based therapeutics for BC exploring original articles focusing on in vivo experiments.

Methods

The current systematic review was performed according to PRISMA guidelines. PubMed and EMBASE databases were comprehensively explored to perform the article search.

Results

Twenty-one eligible studies were included and analyzed: twelve focused on antitumor miR-based therapeutics and nine on metastatic miR-based therapeutics. We found 18 different miRs tested as potential therapeutic molecules in animal model experiments. About 90% of the selected studies evaluate the efficiency and the safety of miRs as therapeutic agents in triple-negative (TN)-BC mouse models. Among all founded miR-based therapeutics, miR-21 emerged to be the most investigated and proposed as a potential antitumoral molecule for TNBC treatment. Besides, miR-34a and miR-205a appeared to be successful antitumoral and antimetastatic molecules.

Conclusions

Our analysis provides a snapshot of the current scenario regarding the miRs as therapeutic molecules in BC. Nevertheless, despite many efforts, none of the selected studies goes beyond preclinical studies, and their translatability in the clinical practice seems quite premature.

The Interplay Between Programmed Death Ligand 1 and Vimentin in Advanced Non-Small-Cell Lung Cancer

Background

Current therapy for non-small-cell lung cancer (NSCLC) frequently includes immune checkpoint inhibitors, such as pembrolizumab, and programmed death ligand 1 (PD-L1) positivity is mandatory for its use in this setting. Vimentin plays a role in carcinogenesis through the activation of the epithelial-to-mesenchymal transition (EMT) process. Its prognostic impact in NSCLC has been investigated in numerous studies but little data are available on its relation with PD-L1 expression.

Patients and Methods

We retrospectively retrieved data on patients with advanced NSCLC consecutively enrolled in a clinical trial at our institute. PD-L1 and vimentin expression were determined by immunohistochemistry. Correlations between variables were assessed using the Spearman correlation coefficient. The Kaplan-Meier method was used to estimate overall survival (OS) and the Log-rank test was used to compare survival curves. The association between demographic, clinical and biomarker information and survival was investigated with the Cox model.

Results

Fifty-three patients were included in the study. A weak positive correlation was observed between the PD-L1 and vimentin (ρ=0.41, P=0.003). Patients with PD-L1 values <1% showed a slightly better OS than those with higher values (HR=2.07; 95% CI: 0.92-4.65), but the difference was not significant (P=0.080). No difference in overall survival (OS) was observed on the basis of vimentin expression (HR=1.25; 95% CI: 0.59-2.66; P=0.554). Patients harboring both vimentin and PD-L1 negative expression (<1%) showed a trend towards better survival than those with ≥1% expression (HR=2.31; 95% CI: 0.87-6.17, P=0.093). No significant associations were observed between gender, age at diagnosis, stage at diagnosis, histology, KRAS or EGFR status, radical surgery or immunotherapy and OS.

Conclusions

The weak positive association between PD-L1 and vimentin suggests a potential interplay between these biomarkers. Further research is warranted to evaluate EMT and immune escape as two components of the same process.

Female Gender Predicts Augmented Immune Infiltration in Lung Adenocarcinoma

INTRODUCTION

Immune infiltration in lung adenocarcinomas (LUADs) has been associated with response to immune checkpoint inhibitors. Clinical features underlying differential responses of patients with LUADs to immunotherapy are not well understood. Here, we analyzed the association between LUAD immune infiltration and clinicopathologic variables.

MATERIALS AND METHODS

Intratumoral CD3, CD8, and CD68 cell densities (tumor-associated immune cells [TAICs]) were immunohistochemically assessed in 146 surgically resected LUADs. LUADs were classified into 2 groups, low and high TAICs, based on the median values of cell densities for CD3, CD8, and CD68. Somatic mutation burden and driver gene mutation status were analyzed in a subset of the cases (n = 92). We statistically analyzed the association between the TAIC groups and various clinicopathologic and molecular variables by using the χ²/Fisher and Wilcoxon sum tests and multivariable logistic regression models.

RESULTS

Patient gender, tumor size, and STK11 mutations were significantly associated with TAIC levels in LUAD. Female patients exhibited significantly elevated TAIC levels (P = .005) compared with male patients. Tumor size was inversely associated with TAIC levels (P = .012). STK11 mutated tumors were associated with lower TAICs (P = .008). Higher TAICs were consistently observed in female patients with LUADs after adjusting for stage, tumor size, and age. Multivariable regression models confirmed female gender as an independent variable associated with TAIC levels in LUAD (P = .0141).

CONCLUSION

Immune infiltration in LUADs was significantly higher in female patients, warranting further exploration into the association between this clinical variable and immunotherapeutic response in LUAD.

PD-L1 recruits phospholipase C and enhances tumorigenicity of lung tumors harboring mutant forms of EGFR

Cancer immunotherapy focuses on inhibitors of checkpoint proteins, such as programmed death ligand 1 (PD-L1). Unlike RAS-mutated lung cancers, EGFR mutant tumors have a generally low response to immunotherapy. Because treatment outcomes vary by EGFR allele, intrinsic and microenvironmental factors may be involved. Among all non-immunological signaling pathways surveyed in patients’ datasets, EGFR signaling is best associated with high PD-L1. Correspondingly, active EGFRs stabilize PD-L1 transcripts and depletion of PD-L1 severely inhibits EGFR-driven tumorigenicity and metastasis in mice. The underlying mechanisms involve the recruitment of phospholipase C-γ1 (PLC-γ1) to a cytoplasmic motif of PD-L1, which enhances PLC-γ1 activation by EGFR. Once stimulated, PLC-γ1 activates calcium flux, Rho GTPases, and protein kinase C, collectively promoting an aggressive phenotype. Anti-PD-L1 antibodies can inhibit these intrinsic functions of PD-L1. Our results portray PD-L1 as a molecular amplifier of EGFR signaling and improve the understanding of the resistance of EGFR⁺ tumors to immunotherapy.

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Unlike promoter-mediated PD-L1 induction by IFN-γ, EGFR rapidly stabilizes PD-L1 mRNA

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Once induced, PD-L1 enhances metastasis in vivo and chemotaxis toward EGF

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PD-L1 physically binds with and enhances activation of phospholipase C-γ1 by EGFR

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PLC-γ1 binds a PD-L1’s cytoplasmic segment implicated in protection from cytotoxicity

Tumor-derived extracellular vesicles containing microRNA-1290 promote immune escape of cancer cells through the Grhl2/ZEB1/PD-L1 axis in gastric cancer

Gastric cancer (GC) is a highly prevalent malignancy featured by dismal oncological outcomes. Accumulating pieces of evidence have consensus over the therapeutic significance of extracellular vesicles (EVs) and its role in carcinogenesis. Here, we planned to uncover EVs' role in GC by shuttling microRNA-1290 (miR-1290) and to identify the possible molecular mechanism associated with Grhl2, PD-L1, and ZEB1. Grhl2 was under-expressed in GC tissues, exhibiting a negative correlation with PD-L1 expression. In addition, Grhl2 promoted T cell proliferation by down-regulating PD-L1 via inhibiting ZEB1, while miR-1290 was found to negatively regulate Grhl2. EVs were also isolated from GC cells or normal gastric epithelial cells and identified with the presence of EV markers. miR-1290 expression was determined to be enriched in the EVs derived from GC cells and observed to promote the suppressive action of GC cells on T cell activation by up-regulating PD-L1 via the Grhl2/ZEB1 pathway in the co-culture system of GC cells with or without treatment of EVs with T cells. Moreover, we also developed a mouse model of GC and injected the EVs derived from miR-1290-inhibitor-treated GC cells into the tumor-bearing mice for further validation of mechanism in vivo. Intriguingly, the pivotal role of EVs-shuttled miR-1290 as an oncomiR was demonstrated in vivo. Collectively, we found that miR-1290 in EVs secreted from GC cells contributed to immune escape through the Grhl2/ZEB1/PD-L1 axis.

Zeb1 induces immune checkpoints to form an immunosuppressive envelope around invading cancer cells

The PDL1-PD1 immune checkpoint inhibits T cell activation, and its blockade is effective in a subset of patients. Studies are investigating how checkpoints are hijacked by cancer cells and why most patients remain resistant to immunotherapy. Epithelial mesenchymal transition (EMT), which drives tumor cell invasion via the Zeb1 transcription factor, is linked to immunotherapy resistance. In addition, M2-polarized tumor-associated macrophages (TAMs), which inhibit T cell migration and activation, may also cause immunotherapy resistance. How EMT in invading cancer cells is linked to therapy resistance and events driving TAM M2 polarization are therefore important questions. We show that Zeb1 links these two resistance pathways because it is required for PDL1 expression on invading lung cancer cells, and it also induces CD47 on these invading cells, which drives M2 polarization of adjacent TAMs. Resulting reprogramming of the microenvironment around invading cells shields them from the hostile inflammatory environment surrounding tumors.

Glioma stem cells invasive phenotype at optimal stiffness is driven by MGAT5 dependent mechanosensing

BACKGROUND

Glioblastomas stem-like cells (GSCs) by invading the brain parenchyma, remains after resection and radiotherapy and the tumoral microenvironment become stiffer. GSC invasion is reported as stiffness sensitive and associated with altered N-glycosylation pattern. Glycocalyx thickness modulates integrins mechanosensing, but details remain elusive and glycosylation enzymes involved are unknown. Here, we studied the association between matrix stiffness modulation, GSC migration and MGAT5 induced N-glycosylation in fibrillar 3D context.

METHOD

To mimic the extracellular matrix fibrillar microenvironments, we designed 3D-ex-polyacrylonitrile nanofibers scaffolds (NFS) with adjustable stiffnesses by loading multiwall carbon nanotubes (MWCNT). GSCs neurosphere were plated on NFSs, allowing GSCs migration and MGAT5 was deleted using CRISPR-Cas9.

RESULTS

We found that migration of GSCs was maximum at 166 kPa. Migration rate was correlated with cell shape, expression and maturation of focal adhesion (FA), Epithelial to Mesenchymal Transition (EMT) proteins and (β1,6) branched N-glycan binding, galectin-3. Mutation of MGAT5 in GSC inhibited N-glycans (β1-6) branching, suppressed the stiffness dependence of migration on 166 kPa NFS as well as the associated FA and EMT protein expression.

CONCLUSION

MGAT5 catalysing multibranched N-glycans is a critical regulators of stiffness induced invasion and GSCs mechanotransduction, underpinning MGAT5 as a serious target to treat cancer.

A collagen glucosyltransferase drives lung adenocarcinoma progression in mice

Cancer cells are a major source of enzymes that modify collagen to create a stiff, fibrotic tumor stroma. High collagen lysyl hydroxylase 2 (LH2) expression promotes metastasis and is correlated with shorter survival in lung adenocarcinoma (LUAD) and other tumor types. LH2 hydroxylates lysine (Lys) residues on fibrillar collagen's amino- and carboxy-terminal telopeptides to create stable collagen cross-links. Here, we show that electrostatic interactions between the LH domain active site and collagen determine the unique telopeptidyl lysyl hydroxylase (tLH) activity of LH2. However, CRISPR/Cas-9-mediated inactivation of tLH activity does not fully recapitulate the inhibitory effect of LH2 knock out on LUAD growth and metastasis in mice, suggesting that LH2 drives LUAD progression, in part, through a tLH-independent mechanism. Protein homology modeling and biochemical studies identify an LH2 isoform (LH2b) that has previously undetected collagen galactosylhydroxylysyl glucosyltransferase (GGT) activity determined by a loop that enhances UDP-glucose-binding in the GLT active site and is encoded by alternatively spliced exon 13 A. CRISPR/Cas-9-mediated deletion of exon 13 A sharply reduces the growth and metastasis of LH2b-expressing LUADs in mice. These findings identify a previously unrecognized collagen GGT activity that drives LUAD progression.

Atezolizumab and blockade of LncRNA PVT1 attenuate cisplatin resistant ovarian cancer cells progression synergistically via JAK2/STAT3/PD-L1 pathway

OBJECTIVE

To investigate the relationship between lncRNA PVT1(PVT1) level and PD-L1 expression and their functions in cisplatin resistant epithelial ovarian cancer (CREOC).

METHODS

PVT1 and PD-L1 in ovarian cancer tissues were detected and analyzed. The cells proliferation, apoptosis, invasion abilities and potential mechanism were detected by cell functional experiments and western-blot assay, respectively.

RESULTS

The average expressions of PVT1 and PD-L1 in CREOC tissues were significantly higher. The expression of PVT1 is positively associated with PD-L1 in CREOC. Higher expressions of PVT1 and PD-L1 indicated more malignant clinical behavior and shorter PFS and OS. Knockdown of PVT1 inhibited the proliferation and invasion and promote apoptosis for A2780cis cells, which may be related to decrease the expression of PD-L1 via repressing JAK2/STAT3 pathway.

CONCLUSIONS

The synergistic therapeutic strategy using LncRNA PVT1-targeted therapy and immune checkpoint blockade of PD-L1 warrant study further for ovarian cancer patients with cisplatin resistant recurrence.

The emerging role of miRNA in the perturbation of tumor immune microenvironment in chemoresistance: Therapeutic implications

Chemoresistance is a major hindrance in cancer chemotherapies, a leading cause of tumor recurrence and cancer-related deaths. Cancer cells develop numerous strategies to elude immune attacks and are regulated by immunological factors. Cancer cells can alter the expression of several immune modulators to upregulate the activities of immune checkpoint pathways. Targeting the immune checkpoint inhibitors is a part of the cancer immunotherapy altered during carcinogenesis. These immune modulators have the capability to reprogram the tumor microenvironment, thereby change the efficacy of chemotherapeutics. In general, the sensitivity of drugs is reduced in the immunosuppressive tumor microenvironment, resulting in chemoresistance and tumor relapse. The regulation of microRNAs (miRNAs) is well established in cancer initiation, progression, and therapy. Intriguingly, miRNA affects cancer immune surveillance and immune response by targeting immune checkpoint inhibitors in the tumor microenvironment. miRNAs alter the gene expression at the post-transcriptional level, which modulates both innate and adaptive immune systems. Alteration of tumor immune microenvironment influences drug sensitivity towards cancer cells. Besides, the expression profile of immune-modulatory miRNAs can be used as a potential biomarker to predict the response and clinical outcomes in cancer immunotherapy and chemotherapy. Recent evidences have revealed that cancer-derived immune-modulatory miRNAs might be promising targets to counteract cancer immune escape, thereby increasing drug efficacy. In this review, we have compiled the role of miRNAs in overcoming the chemoresistance by modulating tumor microenvironment and discussed their preclinical and clinical implications.

Frontiers of MicroRNA Signature in Non-small Cell Lung Cancer

Lung cancer is the leading cause of cancer-related deaths worldwide and non-small cell lung cancer (NSCLC) accounts for more than 80% of all lung cancer cases. Recent advancements in diagnostic tools, surgical treatments, chemotherapies, and molecular targeted therapies that improved the therapeutic efficacy in NSCLC. However, the 5-years relative survival rate of NSCLC is only about 20% due to the inadequate screening methods and late onset of clinical symptoms. Dysregulation of microRNAs (miRNAs) was frequently observed in NSCLC and closely associated with NSCLC development, progression, and metastasis through regulating their target genes. In this review, we provide an updated overview of aberrant miRNA signature in NSCLC, and discuss the possibility of miRNAs becoming a diagnostic and therapeutic tool. We also discuss the possible causes of dysregulated miRNAs in NSCLC.

The Roles of Programmed Cell Death Ligand-1/ Programmed Cell Death-1 (PD-L1/PD-1) in HPV-induced Cervical Cancer and Potential for their Use in Blockade Therapy

BACKGROUND

Cervical cancer induced by infection with human papillomavirus (HPV) remains a leading cause of mortality for women worldwide although preventive vaccines and early diagnosis have reduced morbidity and mortality. Advanced cervical cancer can only be treated with either chemotherapy or radiotherapy but the outcomes are poor. The median survival for advanced cervical cancer patients is only 16.8 months.

METHODS

We undertook a structural search of peer-reviewed published studies based on 1). Characteristics of programmed cell death ligand-1/programmed cell death-1(PD-L1/PD-1) expression in cervical cancer and upstream regulatory signals of PD-L1/PD-1 expression, 2). The role of the PD-L1/PD-1 axis in cervical carcinogenesis induced by HPV infection and 3). Whether the PD-L1/PD-1 axis has emerged as a potential target for cervical cancer therapies.

RESULTS

One hundred and twenty-six published papers were included in the review, demonstrating that expression of PD-L1/PD-1 is associated with HPV-caused cancer, especially with HPV 16 and 18 which account for approximately 70% of cervical cancer cases. HPV E5/E6/E7 oncogenes activate multiple signalling pathways including PI3K/AKT, MAPK, hypoxia-inducible factor 1α, STAT3/NF-kB and microRNA, which regulate PD-L1/PD-1 axis to promote HPV-induced cervical carcinogenesis. The PD-L1/PD-1 axis plays a crucial role in the immune escape of cervical cancer through inhibition of host immune response. Creating an "immune-privileged" site for initial viral infection and subsequent adaptive immune resistance, which provides a rationale for the therapeutic blockade of this axis in HPV-positive cancers. Currently, Phase I/II clinical trials evaluating the effects of PDL1/ PD-1 targeted therapies are in progress for cervical carcinoma, which provide an important opportunity for the application of anti-PD-L1/anti-PD-1 antibodies in cervical cancer treatment.

CONCLUSION

Recent research developments have led to an entirely new class of drugs using antibodies against the PD-L1/PD-1 thus promoting the body's immune system to fight cancer. The expression and roles of the PD-L1/ PD-1 axis in the progression of cervical cancer provide great potential for using PD-L1/PD-1 antibodies as a targeted cancer therapy.

Tumor Immune Microenvironment during Epithelial-Mesenchymal Transition

Epithelial-mesenchymal transition (EMT) has been shown to play a critical role in tumor development from initiation to metastasis. EMT could be regarded as a continuum, with intermediate hybrid epithelial and mesenchymal phenotypes having high plasticity. Classical EMT is characterized by the phenotype change of epithelial cells to cells with mesenchymal properties, but EMT is also associated with multiple other molecular processes, including tumor immune evasion. Some previous studies have shown that EMT is associated with the cell number of immunosuppressive cells, such as myeloid-derived suppressor cells, and the expression of immune checkpoints, such as programmed cell death-ligand 1, in several cancer types. At the molecular level, EMT transcriptional factors, including Snail, Zeb1, and Twist1, produce or attract immunosuppressive cells or promote the expression of immunosuppressive checkpoint molecules via chemokine production, leading to a tumor immunosuppressive microenvironment. In turn, immunosuppressive factors induce EMT in tumor cells. This feedback loop between EMT and immunosuppression promotes tumor progression. For therapy directly targeting EMT has been challenging, the elucidation of the interactive regulation of EMT and immunosuppression is desirable for developing new therapeutic approaches in cancer. The combination of immune checkpoint inhibitors and immunotherapy targeting immunosuppressive cells could be a promising therapy for EMT.

miRNAs in lung cancer. A systematic review identifies predictive and prognostic miRNA candidates for precision medicine in lung cancer

Lung cancer (LC) is the leading cause of cancer-related death worldwide and miRNAs play a key role in LC development. To better diagnose LC and to predict drug treatment responses we evaluated 228 articles encompassing 16,697 patients and 12,582 healthy controls. Based on the criteria of ≥3 independent studies and a sensitivity and specificity of >0.8 we found blood-borne miR-20a, miR-10b, miR-150, and miR-223 to be excellent diagnostic biomarkers for non-small cell LC whereas miR-205 is specific for squamous cell carcinoma. The systematic review also revealed 38 commonly regulated miRNAs in tumor tissue and the circulation, thus enabling the prediction of histological subtypes of LC. Moreover, theranostic biomarker candidates with proven responsiveness to checkpoint inhibitor treatments were identified, notably miR-34a, miR-93, miR-106b, miR-181a, miR-193a-3p, and miR-375. Conversely, miR-103a-3p, miR-152, miR-152-3p, miR-15b, miR-16, miR-194, miR-34b, and miR-506 influence programmed cell death-ligand 1 and programmed cell death-1 receptor expression, therefore providing a rationale for the development of molecularly targeted therapies. Furthermore, miR-21, miR-25, miR-27b, miR-19b, miR-125b, miR-146a, and miR-210 predicted response to platinum-based treatments. We also highlight controversial reports on specific miRNAs. In conclusion, we report diagnostic miRNA biomarkers for in-depth clinical evaluation. Furthermore, in an effort to avoid unnecessary toxicity we propose predictive biomarkers. The biomarker candidates support personalized treatment decisions of LC patients and await their confirmation in randomized clinical trials.

An Immune Cell-Based Signature Associating With EMT Phenotype Predicts Postoperative Overall Survival of ESCC

Esophageal squamous cell carcinoma (ESCC) is one of the deadliest solid malignancies and has a poor survival rate worldwide. In this study, we aimed to establish a tumor-infiltrating immune cell-based prognosis signature (IPS) to predict patients’ survival times and aid in the development of targeted therapies or immunotherapies. The abundances of 22 types of immune cells were determined by the CIBERSORT algorithm from ESCC patient gene expression data in the Gene Expression Omnibus (GEO) training set (n = 179) and The Cancer Genome Atlas (TCGA) validation set (n = 95). Then, the IPS was established by using the least absolute shrinkage and selection operator (LASSO) regression method. Kaplan-Meier analysis showed that patients with high IPS scores had significantly worse overall survival times than patients with low IPS scores in both the training set and the validation set (log-rank p = 0.001, and p = 0.050, respectively). Univariate and multivariate Cox regression analyses proved that the IPS was a robust prognostic factor for ESCC, independent of age, sex, tumor node metastasis (TNM) stage, pathology grade, and tumor location. In the mechanistic study, the epithelial-mesenchymal transition (EMT) process was identified by both gene set enrichment analysis (GSEA) and weighted correlation network analysis (WGCNA) as the underlying mechanism by which the IPS affects the prognosis of ESCC. After systematic correlation analyses, we found that M2 macrophages were the only cell type in the IPS significantly correlated with the EMT process. This relationship between M2 macrophage infiltration and the EMT phenotype was also confirmed by our preliminary immunochemistry (IHC) and multiplexed immunofluorescence study. In conclusion, we constructed an IPS that predicts the postoperative prognosis of ESCC patients and uncovered the critical role of M2 macrophages in the interplay between immune status and the EMT phenotype in ESCC.

Oleuropin controls miR-194/XIST/PD-L1 loop in triple negative breast cancer: New role of nutri-epigenetics in immune-oncology

Oleuropein, the main secoiridoid glucoside found in Olea europaea L., has attracted scientific community as a potential anticancer agent. Immunotherapy and RNA interference revolutionized cancer treatment. Success of PD-L1/PD-1 antibodies encouraged the investigation of PD-1/PD-L1 regulation by non-coding RNAs. This study aimed to verify the cytotoxic effect of oleuropein on MDA-MB-231 cell line and to unravel novel ceRNA interaction between miR-194-5p and XIST in breast cancer and their immunomodulatory effect on PD-L1 expression to propose a promising prophylactic and preventive role of Oleuropin in diet. For the first time, miR-194/Lnc-RNA XIST/PD-L1 triad was investigated in breast cancer, where miR-194 and PD-L1 levels were significantly upregulated in 21 BC-biopsies, yet XIST was downregulated. Ectopic expression of miR-194 enhanced cell function and viability with concomitant increase in PD-L1 expression yet XIST expression decreased, in contrast to miR-194 antagomirs that yielded opposite results. XIST knock-out elevated miR194-5p and PD-L1 levels. miR-194-5p mimics and XIST siRNAs co-transfection induced PD-L1 expression, while miR-194-5p mimics and TSIX siRNAs co-transfection showed opposite effect. Oleuropein showed anti-carcinogenic impact by decreasing miR-194 and PD-L1 levels while increasing XIST level. In conclusion, our study highlighted novel ceRNA interaction controlling PD-L1 expression in BC. Oleuropein is a promising nutraceutical for cancer therapy. Therefore, oleuropin represents a new nutri-epigenetic in immune-oncology that controls miR-194/XIST/PD-L1 loop in triple negative breast cancer.

An IFNγ/STAT1/JMJD3 Axis Induces ZEB1 Expression and Promotes Aggressiveness in Lung Adenocarcinoma

Active IFNγ signaling is a common feature of tumors responding to PD-1 checkpoint blockade. IFNγ exhibits both anti- and protumor activities. Here, we show that the treatment of lung adenocarcinoma cells with IFNγ led to a rapid increase of ZEB1 expression and a significant change in epithelial-to-mesenchymal transition (EMT)-associated gene expression pattern. Moreover, functional analyses show that IFNγ promoted cell migration in vitro and metastasis in vivo. We demonstrate that ZEB1 is required for IFNγ-promoted EMT, cell migration, and metastasis, as RNAi-mediated knockdown of ZEB1 abrogated EMT, cell migration, and metastasis induced by IFNγ. We show that IFNγ induced upregulation of JMJD3 significantly reduced H3K27 trimethylation in the promoter of the ZEB1 gene, which led to activation of ZEB1 gene transcription. IFNγ-induced JMJD3 expression was JAK1/2-STAT1 dependent. Inhibition of JMJD3 abrogated IFNγ-induced ZEB1 expression. IFNγ-induced ZEB1 also reduced miR-200 expression. Downregulation of ZEB1 increased miR-200 expression, which led to a reduction of PD-L1 expression induced by IFNγ. It is worth noting that knockdown of ZEB1 did not affect IFNγ-mediated antiproliferation and induction of CXCL9 and CXCL10. Thus, downregulation of ZEB1 may prevent the protumor activity of IFNγ while retaining its antitumor function. This study expands our understanding of IFNγ-mediated signaling and helps to identify therapeutic targets to improve current immunotherapies. IMPLICATIONS: IFNγ increases ZEB1 expression in a STAT1-JMJD3 dependent manner, and consequently promotes cancer cell aggressiveness. This study provides a potential target to minimize the procancer effect of IFNγ while preserving its antitumor function.

Circ-HMGA2 (hsa_circ_0027446) promotes the metastasis and epithelial-mesenchymal transition of lung adenocarcinoma cells through the miR-1236-3p/ZEB1 axis

Lung adenocarcinoma (LUAD) has high incidence and mortality rates worldwide; however, its detailed molecular pathology remains unclear. Although circRNAs have gradually been identified as molecules that are differentially expressed in tumors and play key roles in tumor progression, their role in LUAD is poorly understood. Through microarray analysis, we obtained the circRNA expression profile of LUAD and found that circ-HMGA2 (hsa_circ_0027446), a novel RNA, is highly expressed in LUAD. The high expression of circ-HMGA2 was further verified in 36 paired LUAD and adjacent normal tissues. Functionally, circ-HMGA2 promoted LUAD cell metastasis in vitro and in vivo. The luciferase reporter assay and FISH results showed that circ-HMGA2 interacts with miR-1236-3p and that miR-1236-3p interacts with ZEB1. In addition, miR-1236-3p was expressed at low levels in LUAD, inhibited LUAD cell metastasis, and suppressed the function of circ-HMGA2. ZEB1 is an EMT-promoting transcription factor. The PCR and WB analysis results showed that circ-HMGA2 promotes both ZEB1 expression and EMT. MiR-1236-3p had the opposite effect, reversing the promotive effect of circ-HMGA2 on EMT. In summary, circ-HMGA2 promotes LUAD cell metastasis through the miR-1236-3p/EMT axis, indicating that it could be a therapeutic target in LUAD.

miRNA Expression Characterizes Histological Subtypes and Metastasis in Penile Squamous Cell Carcinoma

Although microRNAs are described as promising biomarkers in many tumor types, little is known about their role in PSCC. Thus, we attempted to identify miRNAs involved in tumor development and metastasis in distinct histological subtypes considering the impact of HPV infection. In a first step, microarray analyses were performed on RNA from formalin-fixed, paraffin-embedded tumor (22), and normal (8) tissue samples. Microarray data were validated for selected miRNAs by qRT-PCR on an enlarged cohort, including 27 tumor and 18 normal tissues. We found 876 significantly differentially expressed miRNAs (p ≤ 0.01) between HPV-positive and HPV-negative tumor samples by microarray analysis. Although no significant differences were detected between normal and tumor tissue in the whole cohort, specific expression patterns occurred in distinct histological subtypes, such as HPV-negative usual PSCC (95 differentially expressed miRNAs, p ≤ 0.05) and HPV-positive basaloid/warty subtypes (247 differentially expressed miRNAs, p ≤ 0.05). Selected miRNAs were confirmed by qRT-PCR. Furthermore, microarray data revealed 118 miRNAs (p ≤ 0.01) that were significantly differentially expressed in metastatic versus non-metastatic usual PSCC. The lower expression levels for miR-137 and miR-328-3p in metastatic usual PSCC were validated by qRT-PCR. The results of this study confirmed that specific miRNAs could serve as potential diagnostic and prognostic markers in single PSCC subtypes and are associated with HPV-dependent pathways.

Lung cancer and epithelial-mesenchymal transition

Lung cancer (LC) is a leading cause of cancer-related death worldwide. Epithelial-mesenchymal transition (EMT) is a well-known phenomenon that promotes the invasive and metastatic capabilities of LC. Especially, EMT is assumed to be a pivotal mechanism for tumor cell invasion and metastasis, thereby limiting the efficacy of surgery and medical treatments, resulting in poor patient prognoses. Thus, the elucidation and reversal of EMT could provide changes in therapeutic strategies for LC. To overcome the limitations of currents treatment regimens for LC, it is important for surgeons to be familiar with this complex tumor characteristic. In this review, the activating signaling pathways underlying EMT and the associated tumor phenotypes are briefly described.

Preparation of an Orthotopic, Syngeneic Model of Lung Adenocarcinoma and the Testing of the Antitumor Efficacy of Poly(2-oxazoline) Formulation of Chemo-and Immunotherapeutic Agents

Tumor xenograft models developed by transplanting human tissues or cells into immune-deficient mice are widely used to study human cancer response to drug candidates. However, immune-deficient mice are unfit for investigating the effect of immunotherapeutic agents on the host immune response to cancer (Morgan, 2012). Here, we describe the preparation of an orthotopic, syngeneic model of lung adenocarcinoma (LUAD), a subtype of non-small cell lung cancer (NSCLC), to study the antitumor effect of chemo and immunotherapeutic agents in an immune-competent animal. The tumor model is developed by implanting 344SQ LUAD cells derived from the metastases of KrasG12D; p53R172HΔG genetically engineered mouse model into the left lung of a syngeneic host (Sv/129). The 344SQ LUAD model offers several advantages over other models: 1) The immune-competent host allows for the assessment of the biologic effects of immune-modulating agents; 2) The pathophysiological features of the human disease are preserved due to the orthotopic approach; 3) Predisposition of the tumor to metastasize facilitates the study of therapeutic effects on primary tumor as well as the metastases ( Chen et al., 2014 ). Furthermore, we also describe a treatment strategy based on Poly(2-oxazoline) micelles that has been shown to be effective in this difficult-to-treat tumor model ( Vinod et al., 2020b ).

Restoration of miR-340 controls pancreatic cancer cell CD47 expression to promote macrophage phagocytosis and enhance antitumor immunity

Background

Immune checkpoint blockade has emerged as a potential cancer immunotherapy. The “don’t eat me” signal CD47 in cancer cells binds signal regulatory protein-α on macrophages and prevents their phagocytosis. The role of miR-340 in pancreatic ductal adenocarcinoma (PDAC), especially in tumor immunity, has not been explored. Here, we examined the clinical and biological relevance of miR-340 and the molecular pathways regulated by miR-340 in PDAC.

Methods

CD47 and miR-340 expression and the relationship with cancer patient survival were analyzed by bioinformatics. The mechanism of miR-340 action was explored through bioinformatics, luciferase reporter, qRT-PCR and western blot analyses. The effects of miR-340 on cancer cells were analyzed in terms of apoptosis, proliferation, migration and phagocytosis by macrophages. In vivo tumorigenesis was studied in orthotopic and subcutaneous models, and immune cells from the peripheral and tumor immune microenvironments were analyzed by flow cytometry. Depletion of macrophages was used to verify the role of macrophages in impacting the function of miR-340 in tumor progression.

Results

miR-340 directly regulates and inversely correlates with CD47, and it predicts patient survival in PDAC. The restoration of miR-340 expression in pancreatic cancer cells was sufficient to downregulate CD47 and promote phagocytosis of macrophages, further inhibiting tumor growth. The overexpression of miR-340 promoted macrophages to become M1-like phenotype polarized in peripheral and tumor immune microenvironments and increased T cells, especially CD8⁺ T cells, contributing to the antitumor effect of miR-340.

Conclusions

miR-340 is a key regulator of phagocytosis and antitumor immunity, and it could offer a new opportunity for immunotherapy for PDAC.

PKD3 promotes metastasis and growth of oral squamous cell carcinoma through positive feedback regulation with PD-L1 and activation of ERK-STAT1/3-EMT signalling

Oral squamous cell carcinoma (OSCC) has a high incidence of metastasis. Tumour immunotherapy targeting PD-L1 or PD-1 has been revolutionary; however, only a few patients with OSCC respond to this treatment. Therefore, it is essential to gain insights into the molecular mechanisms underlying the growth and metastasis of OSCC. In this study, we analysed the expression levels of protein kinase D3 (PKD3) and PD-L1 and their correlation with the expression of mesenchymal and epithelial markers. We found that the expression of PKD3 and PD-L1 in OSCC cells and tissues was significantly increased, which correlated positively with that of mesenchymal markers but negatively with that of epithelial markers. Silencing PKD3 significantly inhibited the growth, metastasis and invasion of OSCC cells, while its overexpression promoted these processes. Our further analyses revealed that there was positive feedback regulation between PKD3 and PD-L1, which could drive EMT of OSCC cells via the ERK/STAT1/3 pathway, thereby promoting tumour growth and metastasis. Furthermore, silencing PKD3 significantly inhibited the expression of PD-L1, and lymph node metastasis of OSCC was investigated with a mouse footpad xenograft model. Thus, our findings provide a theoretical basis for targeting PKD3 as an alternative method to block EMT for regulating PD-L1 expression and inhibiting OSCC growth and metastasis.

Epithelial to Mesenchymal Transition Regulates Surface PD-L1 via CMTM6 and CMTM7 Induction in Breast Cancer

Simple Summary

Epithelial to mesenchymal transition (EMT) is a mechanism endowing tumor cells with aggressive properties and escape immune surveillance. Here, we reported that activating EMT process in breast cancer cells upregulates CMTM6, an essential protein required for cell surface expression of PD-L1. In addition to CMTM6, our in silico data on triple negative breast cancer patients showed a positive correlation between EMT markers and two other members of CMTM family (CMTM3 and CMTM7). These results were validated in EMT-inducible MCF-7 model that exhibited a downregulation of cell surface expression of PD-L1 by dual targeting CMTM6 and CMTM7. Considering the prominent role of PD-L1 in tumor immune evasion, our study provides an additional clue on how PD-L1 is regulated in aggressive breast cancer cells and pave the way to assess the therapeutic benefit of EMT inhibitors in combination with anti PD-L1 blockade in highly aggressive breast cancer patients.

Abstract

CMTM6 is a critical regulator of cell surface expression of PD-L1 in tumor cells, but little is known about the transcriptional regulation of CMTM6. Here we report that the expression of CMTM6 positively correlates with the epithelial to mesenchymal transition (EMT) score in breast cancer cell lines and with the major EMT marker Vimentin in triple-negative breast cancers (TNBC). We showed that CMTM6 is concomitantly overexpressed with PD-L1 in breast mesenchymal compared with the epithelial cells. Driving a mesenchymal phenotype in SNAI1-inducible MCF-7 cells (MCF-7^Mes cells) increased both PD-L1 and CMTM6. CMTM6 silencing in MCF-7^Mes cells partially reduced cell surface expression of PD-L1, indicating that a proportion of the PD-L1 on the surface of MCF-7^Mes cells depends on CMTM6. We also found a positive correlation between CMTM3 and CMTM7 expression with EMT score in breast cancer cells, and with Vimentin in TNBC patients. Dual knockdown of CMTM6 and CMTM7 significantly decreased PD-L1 surface expression in MCF-7^Mes cells, indicating that both CMTM6 and CMTM7 regulate the expression of PD-L1. This study highlights the importance of CMTM6 and CMTM7 in EMT-induced PD-L1 and suggests that EMT, CMTM6 or CMTM7 modulators can be combined with anti-PD-L1 in patients with highly aggressive breast cancer.

N-cadherin inhibitor creates a microenvironment that protect TILs from immune checkpoints and Treg cells

BACKGROUND

Few patients with prostate cancer benefit from current immunotherapies. Therefore, we aimed to explore new strategies to change this paradigm.

METHODS

Human tissues, cell lines and in vivo experiments were used to determine whether and how N-cadherin impacts the production of programmed death ligand-1 (PD-L1) and indole amine 2,3-dioxygenase (IDO-1) and whether N-cadherin can increase the production of effector (e)Treg cells. Then, we used PC3-bearing humanized non-obese diabetic/severe combined immunodeficiency IL2Rγnull (hNSG) mice with an intravenous injection of human CD34+ hematopoietic stem cells into the tail vein to evaluate whether the N-cadherin antagonist N-Ac-CHAVC-NH2 (designated ADH-1) could improve the therapeutic effect of tumor-infiltrating lymphocyte (TIL)-related treatment.

RESULTS

N-cadherin dramatically upregulated the expression of PD-L1 and IDO-1 through IFN-γ (interferongamma) signaling and increasing the production of free fatty acids that could promote the generation of eTreg cells. In preclinical experiments, immune reconstitution mediated by TILs slowed tumor growth and extended the survival time; however, this effect disappeared after immune system suppression by PD-L1, IDO-1 and eTreg cells. Furthermore, ADH-1 effectively reduced immunosuppression and enhanced TIL-related therapy.

CONCLUSIONS

These data show that the N-cadherin antagonist ADH-1 promotes TIL antitumor responses. This important hurdle must be overcome for tumors to respond to immunotherapy.

HuR up-regulates cell surface PD-L1 via stabilizing CMTM6 transcript in cancer

Despite the well-established role of CMTM6 in the stabilization of cell surface PD-L1 in cancer cells, the mechanisms underlying CMTM6 expression and regulation are still largely unknown. Here we unexpectedly find a strikingly positive correlation between CMTM6 and Hu-Antigen R (HuR) expression in most types of cancer. Mechanistically, we elucidate HuR stabilizes CMTM6 mRNA via direct association with AU-rich elements (AREs) in its 3′UTR and predominantly up-regulates CMTM6, which is readily abolished by HuR-specific inhibitor, MS-444. Phenotypically, we notice abundant cell surface PD-L1 in HuR-high cancer cells, which significantly inhibits immune activation of co-cultured T cells as indicated by IL-2 production. Treatment with MS-444 completely relieves immune suppression imposed by HuR-overexpression and further stimulates immune responses. Ectopic HuR accelerates allograft tumor progression in vivo, which is greatly compromised by simultaneous administration with MS-444. Our study uncovers a novel mechanism in control of CMTM6 and therefore PD-L1 expression, and suggests the potential of combining HuR inhibitor with PD-1/PD-L1 antibodies for cancer immunotherapy.

The mutational load and a T-cell inflamed tumour phenotype identify ovarian cancer patients rendering tumour-reactive T cells from PD-1+ tumour-infiltrating lymphocytes

BACKGROUND

Adoptive immunotherapy with tumour-infiltrating lymphocytes (TIL) may benefit from the use of selective markers, such as PD-1, for tumour-specific T-cell enrichment, and the identification of predictive factors that help identify those patients capable of rendering tumour-reactive TILs. We have investigated this in ovarian cancer (OC) patients as candidates for TIL therapy implementation.

METHODS

PD-1- and PD-1+ CD8 TILs were isolated from ovarian tumours and expanded cells were tested against autologous tumour cells. Baseline tumour samples were examined using flow cytometry, multiplexed immunofluorescence and Nanostring technology, for gene expression analyses, as well as a next-generation sequencing gene panel, for tumour mutational burden (TMB) calculation.

RESULTS

Tumour-reactive TILs were detected in half of patients and were exclusively present in cells derived from the PD-1+ fraction. Importantly, a high TIL density in the fresh tumour, the presence of CD137+ cells within the PD-1+CD8+ TIL subset and their location in the tumour epithelium, together with a baseline T-cell-inflamed genetic signature and/or a high TMB, are features that identify patients rendering tumour-reactive TIL products.

CONCLUSION

We have demonstrated that PD-1 identifies ovarian tumour-specific CD8 TILs and has uncovered predictive factors that identify OC patients who are likely to render tumour-specific cells from PD-1+ TILs.

Relevance of PD-L1 Non-Coding Polymorphisms on the Prognosis of a Genetically Admixed NSCLC Cohort

Purpose

Although non-small cell lung cancer (NSCLC) remains a deadly disease, new predictive biomarkers have emerged to assist in managing the disease, of which one of the most promising is the programmed death‐ligand 1 (PD-L1). Each, PD-L1 variant seem to modulate the function of immune checkpoints differently and affect response to adjuvant treatment and outcome in NSCLC patients. We thus investigated the influence of these PD-L1 genetic variations in genetically admixed NSCLC tissue samples, and correlated these values with clinicopathological characteristics, including prognosis.

Materials and Methods

We evaluated PD-L1 non-coding genetic variants and protein expression in lung adenocarcinomas (ADC), squamous cell carcinomas (SqCC), and large cell carcinomas (LCC) in silico. Microarray paraffin blocks from 70 samples of ADC (N=33), SqCC (N=24), and LCC (N=13) were used to create PD-L1 multiplex immunofluorescence assays with a Cell Signaling E1L3N clone. Fifteen polymorphisms of the PD-L1 gene were investigated by targeted sequencing and evaluated in silico using dedicated tools.

Results

Although PD-L1 polymorphisms seemed not to interfere with protein expression, PD-L1 expression varied among different histological subtypes, as did clinical outcomes, with the rs4742098A>G, rs4143815G>C, and rs7041009G>A variants being associated with relapse (P=0.01; P=0.05; P=0.02, respectively). The rs7041009 GG genotype showed a significant correlation with younger and alive patients compared to carriers of the A allele (P=0.02 and P<0.01, respectively). The Cox regression model showed that the rs7041009 GG genotype may influence OS (P<0.01) as a co-dependent factor associated with radiotherapy and recurrence in NSCLC patients. Furthermore, the Kaplan–Meier survival curves showed that rs7041009 and rs4742098 might impact PPS in relapsed patients. In silico approaches identified the variants as benign.

Conclusion

PD-L1 non-coding variants play an important role in modulating immune checkpoint function and may be explored as immunotherapy biomarkers. We highlight the rs7041009 variant, which impacts OS and PPS in NSCLC patients.

MicroRNA-Based Therapeutics for Drug-Resistant Colorectal Cancer

Although therapeutic approaches for patients with colorectal cancer (CRC) have improved in the past decades, the problem of drug resistance still persists and acts as a major obstacle for effective therapy. Many studies have shown that drug resistance is related to reduced drug uptake, modification of drug targets, and/or transformation of cell cycle checkpoints. A growing body of evidence indicates that several microRNAs (miRNAs) may contribute to the drug resistance to chemotherapy, targeted therapy, and immunotherapy by regulating the drug resistance-related target genes in CRC. These drug resistance-related miRNAs may be used as promising biomarkers for predicting drug response or as potential therapeutic targets for treating patients with CRC. In this review, we summarized the recent discoveries regarding anti-cancer drug-related miRNAs and their molecular mechanisms in CRC. Furthermore, we discussed the challenges associated with the clinical application of miRNAs as biomarkers for the diagnosis of drug-resistant patients and as therapeutic targets for CRC treatment.

The emerging role of estrogen related receptorα in complications of non-small cell lung cancers

Approximately 85% of lung cancer cases are recognized as non-small cell lung cancer (NSCLC) with a perilous (13–17%) 5-year survival in Europe and the USA. Although tobacco smoking has consistently emerged as the leading cause of NSCLC complications, its consequences are distinctly manifest with respect to sex bias, due to differential gene and sex hormone expression. Estrogen related receptor α (ERRα), a member of the nuclear orphan receptor superfamily is normally expressed in the lungs, and activates various nuclear genes without binding to the ligands, such as estrogens. In NSCLC ERRα expression is significantly higher compared with healthy individuals. It is well established ERα and ERβ‚ have 93% and 60% identity in the DNA and ligand binding domains, respectively. ERα and ERRα have 69% (70% with ERRα-1) and 34% (35% with ERRα-1) identity, respectively; ERRα and ERRβ‚ have 92 and 61% identity, respectively. However, whether there is distinctive ERRα interaction with mammalian estrogens or concurrent involvement in non-ER signalling pathway activation is not known. Relevant to NSCLC, ERRα promotes proliferation, invasion and migration by silencing the tumor suppressor proteins p53 and pRB, and accelerates G₂-M transition during cell division. Epithelial to mesenchymal transition (EMT) and activation of Slug (an EMT associated transcription factor) are the prominent mechanisms by which ERRα activates NSCLC metastasis. Based on these observations, the present article focuses on the feasibility of antiERRα therapy alone and in combination with antiER as a therapeutic strategy for NSCLC complications.

Circular RNA circ_0079593 enhances malignant melanoma progression by the regulation of the miR-573/ABHD2 axis

BACKGROUND

Malignant melanoma is the most fatal type of skin tumor. Circular RNAs (circRNAs) have been implicated in the malignant progression of melanoma.

OBJECTIVE

The main purpose of this paper was to identify the precise parts of circ_0079593 in the malignant progression of melanoma.

METHODS

The levels of circ_0079593, miR-573 and abhydrolase domain containing 2 (ABHD2) were determined by quantitative real-time polymerase chain reaction (qRT-PCR) and western blot. Cell proliferation, colony formation, cell cycle progression, apoptosis, migration, and invasion were evaluated using the Cell Counting Kit-8 (CCK-8), colony formation, flow cytometry, and transwell assays, respectively. Targeted correlations among circ_0079593, miR-573 and ABHD2 were confirmed by dual-luciferase reporter, RNA immunoprecipitation (RIP) and RNA pull-down assays. Animal studies were performed to assess the role of circ_0079593 in vivo.

RESULTS

Our data showed that circ_0079593 level was up-regulated in melanoma tissues and cells. The knockdown of circ_0079593 suppressed cell proliferation, cell cycle progression, migration, invasion, and enhanced apoptosis in vitro and inhibited tumor growth in vivo. Mechanistically, circ_0079593 directly targeted miR-573, and circ_0079593 controlled ABHD2 expression by miR-573. MiR-573 mediated the regulation of circ_0079593 on melanoma cell progression in vitro. Moreover, ABHD2 was a functional target of miR-573 in regulating melanoma cell progression in vitro.

CONCLUSION

Our findings identified that the knockdown of circ_0079593 suppressed melanoma progression at least partially through targeting the miR-573/ABHD2 axis, providing evidence for developing circ_0079593 as a promising therapeutic target for melanoma treatment.

MiRNA-138-5p: A strong tumor suppressor targeting PD-L-1 inhibits proliferation and motility of breast cancer cells and induces apoptosis

MicroRNAs are important regulators in multiple cellular processes and are closely related to a variety of cancers including breast cancer (BC). Immunotherapy using different methods such as modulating immune check points has been known as an advanced and successful procedure in cancer treatment. Here we investigated the effects of miRNA-138-5p restoring on Programmed Death Ligand 1 (PD-L-1) expression, BC biological behaviors and T-cell exhaustion. Breast cancer specimens and cell lines were provided and qRT-PCR and western blotting were used to measure the expression of miRNA-138-5p, PD-L-1 and other underlying genes. MTT and colony formation assays and scratch test were employed to specify proliferation, cloning and migration in miRNA-138-5p-transfected MDA-MB-231 cells respectively. DAPI staining assay and flow-cytometry were used to investigate apoptosis rate and cell cycle development. Finally, isolated T-cells were co-cultured with transfected BC cells to explore the effect of miRNA-138-5p on T-cell exhaustion. qRT-PCR revealed down-regulation ofmiRNA-138-5p conversely, up-regulation of PD-L-1 in BC tissues and cell lines. Transfection of miRNA-138-5p into MDA-MB-231 cells inhibited PD-L-1 expression. Western blotting, MTT and colony formation assays affirmed the anti-proliferative effect ofmiRNA-138-5p through down-regulating PI3K/AKT pathway. Also, miRNA-138-5p induced apoptosis in BC cells via up-regulating Caspase-9 and Caspase-3 and arresting cell cycle at sub-G1 phase. Moreover, scratch test and western blotting indicated that miRNA-138-5p inhibits cell motility via targeting MMP2, MMP9 and vimentin but up-regulating E-cadherin. Finally, miRNA-138-5p restrains T-cell exhaustion via suppressing PD-L-1 expression in BC cells leading to disrupt PD-L-1/PD-1 interaction and modulate effector cytokines in T-cells.

Advanced Melanoma: Resistance Mechanisms to Current Therapies

Novel therapeutic agents introduced over the past decade, including immune checkpoint inhibitors and targeted therapies, have revolutionized the management of metastatic melanoma and significantly improved patient outcomes. Although robust and durable responses have been noted in some cases, treatment is often limited by innate or acquired resistance to these agents. This article provides an overview of known and suspected mechanisms involved with acquired resistance to BRAF/MEK inhibitors as well as developing insights into innate and acquired resistance to checkpoint inhibitors in patients with melanoma.

Molecular Mechanisms of Epithelial to Mesenchymal Transition Regulated by ERK5 Signaling

Extracellular signal-regulated kinase (ERK5) is an essential regulator of cancer progression, tumor relapse, and poor patient survival. Epithelial to mesenchymal transition (EMT) is a complex oncogenic process, which drives cell invasion, stemness, and metastases. Activators of ERK5, including mitogen-activated protein kinase 5 (MEK5), tumor necrosis factor α (TNF-α), and transforming growth factor-β (TGF-β), are known to induce EMT and metastases in breast, lung, colorectal, and other cancers. Several downstream targets of the ERK5 pathway, such as myocyte-specific enhancer factor 2c (MEF2C), activator protein-1 (AP-1), focal adhesion kinase (FAK), and c-Myc, play a critical role in the regulation of EMT transcription factors SNAIL, SLUG, and β-catenin. Moreover, ERK5 activation increases the release of extracellular matrix metalloproteinases (MMPs), facilitating breakdown of the extracellular matrix (ECM) and local tumor invasion. Targeting the ERK5 signaling pathway using small molecule inhibitors, microRNAs, and knockdown approaches decreases EMT, cell invasion, and metastases via several mechanisms. The focus of the current review is to highlight the mechanisms which are known to mediate cancer EMT via ERK5 signaling. Several therapeutic approaches that can be undertaken to target the ERK5 pathway and inhibit or reverse EMT and metastases are discussed.

Lung cancer models reveal SARS-CoV-2-induced EMT contributes to COVID-19 pathophysiology

COVID-19 is an infectious disease caused by SARS-CoV-2, which enters host cells via the cell surface proteins ACE2 and TMPRSS2. Using a variety of normal and malignant models and tissues from the aerodigestive and respiratory tracts, we investigated the expression and regulation of ACE2 and TMPRSS2. We find that ACE2 expression is restricted to a select population of highly epithelial cells. Notably, infection with SARS-CoV-2 in cancer cell lines, bronchial organoids, and patient nasal epithelium, induces metabolic and transcriptional changes consistent with epithelial to mesenchymal transition (EMT), including upregulation of ZEB1 and AXL, resulting in an increased EMT score. Additionally, a transcriptional loss of genes associated with tight junction function occurs with SARS-CoV-2 infection. The SARS-CoV-2 receptor, ACE2, is repressed by EMT via TGFbeta, ZEB1 overexpression and onset of EGFR TKI inhibitor resistance. This suggests a novel model of SARS-CoV-2 pathogenesis in which infected cells shift toward an increasingly mesenchymal state, associated with a loss of tight junction components with acute respiratory distress syndrome-protective effects. AXL-inhibition and ZEB1-reduction, as with bemcentinib, offers a potential strategy to reverse this effect. These observations highlight the utility of aerodigestive and, especially, lung cancer model systems in exploring the pathogenesis of SARS-CoV-2 and other respiratory viruses, and offer important insights into the potential mechanisms underlying the morbidity and mortality of COVID-19 in healthy patients and cancer patients alike.

Cancer Stem Cells-Key Players in Tumor Relapse

Tumor relapse and treatment failure are unfortunately common events for cancer patients, thus often rendering cancer an uncurable disease. Cancer stem cells (CSCs) are a subset of cancer cells endowed with tumor-initiating and self-renewal capacity, as well as with high adaptive abilities. Altogether, these features contribute to CSC survival after one or multiple therapeutic approaches, thus leading to treatment failure and tumor progression/relapse. Thus, elucidating the molecular mechanisms associated with stemness-driven resistance is crucial for the development of more effective drugs and durable responses. This review will highlight the mechanisms exploited by CSCs to overcome different therapeutic strategies, from chemo- and radiotherapies to targeted therapies and immunotherapies, shedding light on their plasticity as an insidious trait responsible for their adaptation/escape. Finally, novel CSC-specific approaches will be described, providing evidence of their preclinical and clinical applications.

MicroRNAs: Emerging oncogenic and tumor-suppressive regulators, biomarkers and therapeutic targets in lung cancer

Lung cancer is one of the most common solid tumors worldwide and the leading cause of cancer-related deaths, causing a devastating impact on human health. The clinical prognosis of lung cancer is usually restricted by delayed diagnosis and resistance to anticancer therapies. MicroRNAs, a range of small endogenous noncoding RNAs 22 nucleotides in length, have emerged as one of the most important players in cancer initiation and progression in recent decades. Current evidence reveals pivotal roles of microRNAs in regulating cell proliferation, migration, invasion and metastasis in lung cancer. An increasing number of preclinical and clinical studies have also explored the potential of microRNAs as promising biomarkers and new therapeutic targets for lung cancer. The current review summarizes the most recent progress on the functional mechanisms of microRNAs involved in lung cancer development and progression and further discusses the clinical application of miRNAs as putative therapeutic targets for molecular diagnosis and prognostic prediction in lung cancer.

MicroRNAs in the Tumor Microenvironment

The tumor microenvironment (TME) is decisive for the eradication or survival of any tumor mass. Moreover, it plays a pivotal role for metastasis and for providing the metastatic niche. The TME offers special physiological conditions and is composed of, for example, surrounding blood vessels, the extracellular matrix (ECM), diverse signaling molecules, exosomes and several cell types including, but not being limited to, infiltrated immune cells, cancer-associated endothelial cells (CAEs), and cancer-associated fibroblasts (CAFs). These cells can additionally and significantly contribute to tumor and metastasis progression, especially also by acting via their own deregulated micro (mi) RNA expression or activity. Thus, miRNAs are essential players in the crosstalk between cancer cells and the TME. MiRNAs are small non-coding (nc) RNAs that typically inhibit translation and stability of messenger (m) RNAs, thus being able to regulate several cell functions including proliferation, migration, differentiation, survival, invasion, and several steps of the metastatic cascade. The dynamic interplay between miRNAs in different cell types or organelles such as exosomes, ECM macromolecules, and the TME plays critical roles in many aspects of cancer development. This chapter aims to give an overview on the multiple contributions of miRNAs as players within the TME, to summarize the role of miRNAs in the crosstalk between different cell populations found within the TME, and to illustrate how they act on tumorigenesis and the behavior of cells in the TME context. Lastly, the potential clinical utility of miRNAs for cancer therapy is discussed.

Comprehensive Gene Expression Analyses of Immunohistochemically Defined Subgroups of Muscle-Invasive Urinary Bladder Urothelial Carcinoma

A number of urinary bladder urothelial carcinoma (UB UC) mRNA-based classification systems have been reported. It also has been observed that treatment response and prognosis are different for each molecular subtype. In this study, cytokeratin (CK)5/6 and CK20 immunohistochemistry (IHC) were performed, and IHC-based subgroup classification was applied. UB UC was classified into CK5/6 single-positive (SP), CK20 SP, double-positive (DP) and double-negative (DN) subgroups, and transcriptional analysis was performed. The results of gene ontology (GO) terms and functional analysis using differentially expressed genes indicate that, CK5/6 SP and DP subgroups were enriched in cell migration, immune activation, interleukin 6-Janus kinase-signal transducer and activator of transcription 3 (IL6-JAK-STAT3) signaling pathway and tumor necrosis factor-α signaling via the nuclear factor-κB (NF-κB) signaling pathway signature gene. In addition, compared with the other subgroups, the DN subgroup showed inhibited cell movement, cell migration, and cell activation. Furthermore, in survival analysis, the CK5/6 SP subgroup was significantly associated with poor progression-free survival (p = 0.008). The results of our study indicate that the CK5/6 positive subgroup exhibited high gene expression signature related to aggressive behavior and exhibited worse clinical outcome.

Prognostic impact of the tumor immune microenvironment in pulmonary pleomorphic carcinoma

INTRODUCTION

Pulmonary pleomorphic carcinoma (PC) is a rare non-small cell lung carcinoma (NSCLC) and is characterized by sarcomatoid and NSCLC components. This study aimed to characterize the association between immune microenvironmental factors and clinicopathological characteristics of PC.

METHODS

Eighty consecutive PC patients who had undergone complete surgical resection were enrolled. We calculated the immunohistochemical staining scores for E-cadherin, vimentin, programmed death ligand 1 (PD-L1), and carbonic anhydrase IX in cancer cells and counted the numbers of CD204-positive tumor-associated macrophages (TAMs) and Foxp3-, CD8-, and CD20-positive tumor-infiltrating lymphocytes (TILs). We also examined the association between these scores and the prognostic outcomes.

RESULTS

The staining score for PD-L1 in cancer cells and the number of CD204-positive TAMs in the sarcomatoid component were significantly higher than those in the NSCLC component; E-cadherin score in the sarcomatoid component was significantly lower. Patients with high PD-L1 expression in the NSCLC component had significantly longer overall survival (OS) and recurrence-free survival (RFS) than those with low PD-L1 expression in the NSCLC component (OS: p = 0.001, RFS: p = 0.038). Multivariate analysis revealed that high PD-L1 expression in the NSCLC component was an independent favorable prognostic factor for OS (p = 0.018), whereas high PD-L1 expression in the sarcomatoid component was not. The number of CD8-positive TILs was significantly higher in the high PD-L1 expression group than in the low expression group (NSCLC components: p < 0.001).

CONCLUSION

High PD-L1 expression in the NSCLC component may be associated with a favorable prognostic value in pulmonary PC.