MUC1 inhibition leads to decrease in PD-L1 levels via upregulation of miRNAs

Long noncoding RNA LINC00675 drives malignancy in acute myeloid leukemia via the miR-6809 -CDK6 axis

Hematological malignancies such as acute myeloid leukemia (AML) have a low cure rate and a high recurrence rate. Long noncoding RNAs (LNCs) are essential regulators of tumorigenesis and progression. The role of lncRNA LINC00675 in AML has rarely been reported. This study revealed elevated LINC00675 expression in AML that promotes proliferation and inhibits apoptosis. Mechanistically, LINC00675 combines with miR-6809 to promote the expression of CDK6 in vitro and in vivo. Immune-checkpoint genes were expressed more highly in LINC00675-high patients. A high level of LINC00675 expression may make patients more susceptible to palbociclib treatments. In conclusion, our study demonstrated that LINC00675 is an oncogenic lncRNA that enhances the malignancy of AML by upregulating CDK6 expression through miR-6809 sponging, providing a new perspective and feasible target for the diagnosis and treatment of AML.

Mucin 1 promotes salivary gland cancer cell proliferation and metastasis by regulating the epidermal growth factor receptor signaling pathway

Background/purpose

Salivary gland cancer (SGC) is the common malignant tumor of the head and neck region with poor prognosis. Mucin 1 (MUC1) has been reported to be associated with the development of cancer. However, whether MUC1 contributed to the progression of SGC remains to be explored.

Materials and methods

Immunohistochemical analysis was used to explore the expression levels of MUC1 in SGC tissues. Cell proliferation, colony formation, wound healing, transwell, and xenograft assays were performed to examine the effects of MUC1 on SGC in vitro and in vivo.

Results

We found that the expression level of MUC1 was significantly upregulated in SGC tissues, and the expression level of MUC1 was significantly correlated with lymph node metastasis and TNM stage of SGC. Further exploration demonstrated that MUC1 knockdown drastically inhibited, while its overexpression promoted, cell growth, colony formation, migration, and invasion abilities of SGC cells in vitro. MUC1 knockdown significantly inhibited tumor growth in vivo, and vice versa. More importantly, we found that MUC1 promotes malignant phenotypes of SGC cells by regulating the epidermal growth factor receptor (EGFR) signaling pathway.

Conclusion

Our results revealed that MUC1 promotes the development of SGC by mediating the EGFR signaling pathway, which highlights the potential therapeutic target of MUC1/ EGFR in SGC.

Progress of research on PD-1/PD-L1 in leukemia

Leukemia cells prevent immune system from clearing tumor cells by inducing the immunosuppression of the bone marrow (BM) microenvironment. In recent years, further understanding of the BM microenvironment and immune landscape of leukemia has resulted in the introduction of several immunotherapies, including checkpoint inhibitors, T-cell engager, antibody drug conjugates, and cellular therapies in clinical trials. Among them, the programmed cell death protein 1 (PD-1)/programmed death-ligand 1 (PD-L1) axis is a significant checkpoint for controlling immune responses, the PD-1 receptor on tumor-infiltrating T cells is bound by PD-L1 on leukemia cells. Consequently, the activation of tumor reactive T cells is inhibited and their apoptosis is promoted, preventing the rejection of the tumor by immune system and thus resulting in the occurrence of immune tolerance. The PD-1/PD-L1 axis serves as a significant mechanism by which tumor cells evade immune surveillance, and PD-1/PD-L1 checkpoint inhibitors have been approved for the treatment of lymphomas and varieties of solid tumors. However, the development of drugs targeting PD-1/PD-L1 in leukemia remains in the clinical-trial stage. In this review, we tally up the basic research and clinical trials on PD-1/PD-L1 inhibitors in leukemia, as well as discuss the relevant toxicity and impacts of PD-1/PD-L1 on other immunotherapies such as hematopoietic stem cell transplantation, bi-specific T-cell engager, chimeric antigen receptor T-cell immunotherapy.

The multifaceted role of MUC1 in tumor therapy resistance

Tumor therapeutic resistances are frequently linked to the recurrence and poor prognosis of cancers and have been a key bottleneck in clinical tumor treatment. Mucin1 (MUC1), a heterodimeric transmembrane glycoprotein, exhibits abnormally overexpression in a variety of human tumors and has been confirmed to be related to the formation of therapeutic resistance. In this review, the multifaceted roles of MUC1 in tumor therapy resistance are summarized from aspects of pan-cancer principles shared among therapies and individual mechanisms dependent on different therapies. Concretely, the common mechanisms of therapy resistance across cancers include interfering with gene expression, promoting genome instability, modifying tumor microenvironment, enhancing cancer heterogeneity and stemness, and activating evasion and metastasis. Moreover, the individual mechanisms of therapy resistance in chemotherapy, radiotherapy, and biotherapy are introduced. Last but not least, MUC1-involved therapy resistance in different types of cancers and MUC1-related clinical trials are summarized.

The opportunities and challenges in immunotherapy: Insights from the regulation of PD-L1 in cancer cells

The immunosuppressive molecule programmed death-ligand 1 (PD-L1) is frequently upregulated in human cancers. Binding of PD-L1 to its receptor, programmed death-1 (PD-1), on activated T cells facilitates cancer cells to evade the host immune system. Antibody-based PD-1/PD-L1 inhibitors can inhibit PD-1/PD-L1 interaction allowing reactivate cytotoxic T cells to eradicate advanced cancer cells. However, the majority of cancer patients fail to respond to anti-PD-1/PD-L1 therapies and the molecular mechanisms for this remain poorly understood. Recent studies show that PD-L1 expression level on tumor cells affect the clinical efficacy of immune checkpoint therapies. Thus, furthering our understanding of the regulatory mechanisms of PD-L1 expression in cancer cells will be critical to improve clinical response rates and the efficacy of PD-1/PD-L1 immune therapies. Here we review recent studies, primarily focusing on the mechanisms that regulate PD-L1 expression at the transcriptional, post-transcriptional and protein level, with the purpose to drive the development of more targeted and effective anti-PD-1/PD-L1 cancer therapies.

Cytotoxic activity of anti-mucin 1 chimeric antigen receptor T cells expressing PD-1-CD28 switch receptor against cholangiocarcinoma cells

BACKGROUND AIMS

Cholangiocarcinoma (CCA) is a lethal bile-duct cancer that is difficult to treat by current standard procedures. This drawback has prompted us to develop adoptive T-cell therapy for CCA, which requires an appropriate target antigen for binding of chimeric antigen receptor (CAR) T cells. Mucin 1 (MUC1), an overexpressed protein in CCA cells, is a potential target antigen for the CAR T-cell development. However, MUC1 overexpression also is associated with the upregulation of programmed death-ligand 1 (PD-L1), an immune checkpoint protein that prohibits anti-tumor functions of T cells, probably causing poor overall survival of patients with CCA.

METHODS

To overcome this problem, we developed anti-MUC1-CAR T cells containing PD-1-CD28 switch receptor (SR), namely αM.CAR/SR T cells, to target MUC1 and switch on the inhibitory signal of PD-1/PD-L1 interaction to activate CD28 signaling. Our lentiviral construct contains the sequences that encode anti-MUC1-single chain variable fragment, CD137 and CD3ζ, linked with P2A, PD-1 and CD28.

RESULTS

Initially, the upregulations of MUC1 and PD-L1 proteins were confirmed in CCA cell lines. αM.CAR and SR were co-expressed in 53.53 ± 13.89% of transduced T cells, mainly CD8⁺ T cells (85.7 ± 0.75%, P<0.0001) with the effector memory phenotype (59.22 ± 16.31%, P < 0.01). αM.CAR/SR T cells produced high levels of intracellular tumor necrosis factor-α and interferon-γ in response to the activation by CCA cells expressing MUC1, including KKU-055 (27.18 ± 4.38% and 27.33 ± 5.55%, respectively, P < 0.05) and KKU-213A (47.37 ± 12.67% and 54.55 ± 8.66%, respectively, P < 0.01). Remarkably, the cytotoxic function of αM.CAR/SR T cells against KKU-213A cells expressing PD-L1 was significantly enhanced compared with the αM.CAR T cells (70.69 ± 14.38% versus 47.15 ± 8.413%, respectively; P = 0.0301), correlated with increased granzyme B production (60.6 ± 9.89% versus 43.2 ± 8.95%, respectively; P = 0.0402). Moreover, the significantly enhanced disruption of KKU-213A spheroids by αM.CAR/SR T cells (P = 0.0027), compared with αM.CAR T cells, was also observed.

CONCLUSION

Taken together, the cytotoxic function of αM.CAR/SR T cells was enhanced over the αM.CAR T cells, which are potential to be further tested for CCA treatment.

Multi-Targeting Nano-Systems Targeting Heterogeneous Cancer Cells for Therapeutics and Biomarker Detection

Cancer heterogeneity plays a vital part in cancer resistance and metastasis. To provide a reliable approach to exert a therapy action and evaluate its efficiency in heterogeneous cancer cells, a multiple targeting delivery vector composed of histone encapsulating the therapeutic or diagnostic agent, hyaluronic acid targeting CD44 overexpressed in stem tumor cells, SYL3C aptamer targeting epithelial cell adhesion molecule (EpCAM) overexpressed in epithelial cancer cells, and CL4 aptamer targeting epidermal growth factor receptor (EGFR) overexpressed in mesenchymal cancer cells, is developed. The vector can efficiently target different cancer cells and circulating tumor cells (CTCs) in the peripheral blood of patients for mucin 1 (MUC1) knockout. Furthermore, the multiple targeting vector can be used to co-encapsulate three types of molecular beacons for probing various mRNA biomarkers at single-cell resolution after genome editing. This study provides an efficient approach for exerting therapeutic actions in heterogeneous cancer cells and assessing the therapeutic efficacy by detection of cancer biomarkers via liquid biopsy.

Targeting PD-1/PD-L1 pathway in myelodysplastic syndromes and acute myeloid leukemia

Myelodysplastic syndromes (MDS) and acute myeloid leukemia (AML) are clonal hematopoietic stem cell diseases arising from the bone marrow (BM), and approximately 30% of MDS eventually progress to AML, associated with increasingly aggressive neoplastic hematopoietic clones and poor survival. Dysregulated immune microenvironment has been recognized as a key pathogenic driver of MDS and AML, causing high rate of intramedullary apoptosis in lower-risk MDS to immunosuppression in higher-risk MDS and AML. Immune checkpoint molecules, including programmed cell death-1 (PD-1) and programmed cell death ligand-1 (PD-L1), play important roles in oncogenesis by maintaining an immunosuppressive tumor microenvironment. Recently, both molecules have been examined in MDS and AML. Abnormal inflammatory signaling, genetic and/or epigenetic alterations, interactions between cells, and treatment of patients all have been involved in dysregulating PD-1/PD-L1 signaling in these two diseases. Furthermore, with the PD-1/PD-L1 pathway activated in immune microenvironment, the milieu of BM shift to immunosuppressive, contributing to a clonal evolution of blasts. Nevertheless, numerous preclinical studies have suggested a potential response of patients to PD-1/PD-L1 blocker. Current clinical trials employing these drugs in MDS and AML have reported mixed clinical responses. In this paper, we focus on the recent preclinical advances of the PD-1/PD-L1 signaling in MDS and AML, and available and ongoing outcomes of PD-1/PD-L1 inhibitor in patients. We also discuss the novel PD-1/PD-L1 blocker-based immunotherapeutic strategies and challenges, including identifying reliable biomarkers, determining settings, and exploring optimal combination therapies.

Various Uses of PD1/PD-L1 Inhibitor in Oncology: Opportunities and Challenges

The occurrence and development of cancer are closely related to the immune escape of tumor cells and immune tolerance. Unlike previous surgical, chemotherapy, radiotherapy and targeted therapy, tumor immunotherapy is a therapeutic strategy that uses various means to stimulate and enhance the immune function of the body, and ultimately achieves the goal of controlling tumor cells.With the in-depth understanding of tumor immune escape mechanism and tumor microenvironment, and the in-depth study of tumor immunotherapy, immune checkpoint inhibitors represented by Programmed Death 1/Programmed cell Death-Ligand 1(PD-1/PD-L1) inhibitors are becoming increasingly significant in cancer medication treatment. employ a variety of ways to avoid detection by the immune system, a single strategy is not more effective in overcoming tumor immune evasion and metastasis. Combining different immune agents or other drugs can effectively address situations where immunotherapy is not efficacious, thereby increasing the chances of success and alternative access to alternative immunotherapy. Immune combination therapies for cancer have become a hot topic in cancer treatment today. In this paper, several combination therapeutic modalities of PD1/PD-L1 inhibitors are systematically reviewed. Finally, an analysis and outlook are provided in the context of the recent advances in combination therapy with PD1/PD-L1 inhibitors and the pressing issues in this field.

MiR-200c-3p maintains stemness and proliferative potential in adipose-derived stem cells by counteracting senescence mechanisms

Adipose-derived mesenchymal stem cells (ASCs) are promising therapeutic tools in regenerative medicine because they possess self-renewal, differentiation and immunomodulatory capacities. After isolation, ASCs are passaged multiple times in vitro passages to obtain a sufficient amount of cells for clinical applications. During this time-consuming procedure, ASCs become senescent and less proliferative, compromising their clinical efficacy. Here, we sought to investigate how in vitro passages impact ASC proliferation/senescence and expression of immune regulatory proteins. MicroRNAs are pivotal regulators of ASC physiology. Particularly, miR-200c is known to maintain pluripotency and targets the immune checkpoint Programmed death-ligand 1 (PD-L1). We therefore investigated its involvement in these critical characteristics of ASCs during in vitro passages. We found that when transiently expressed, miR-200c-3p promotes proliferation, maintains stemness, and contrasts senescence in late passaged ASCs. Additionally, this miRNA modulates PD-L1 and Indoleamine 2,3-Dioxygenase (IDO1) expression, thus most likely interfering with the immunoregulatory capacity of ASCs. Based on our results, we suggest that expression of miR-200c-3p may prime ASC towards a self-renewing phenotype by improving their in vitro expansion. Contrarily, its inhibition is associated with senescence, reduced proliferation and induction of immune regulators. Our data underline the potential use of miR-200c-3p as a switch for ASCs reprogramming and their clinical application.

MUC1 Promotes Mesangial Cell Proliferation and Kidney Fibrosis in Diabetic Nephropathy Through Activating STAT and β-Catenin Signal Pathway

Diabetic nephropathy (DN) is a complication of diabetes, which leads to most end-stage kidney diseases and threatens health of patients. Mucin 1 (MUC1) is a heterodimeric oncoprotein, which is abnormally expressed in tumors and hematologic diseases. The aim of this study is to clarify the mechanism and role of MUC1 in DN. The mesangial cells (MCs) suffered from high glucose (HG) treatment to mimic DN in vitro. The cell proliferation was detected by Cell Counting Kit-8 assay and 5-ethynyl-2-deoxyuridine (EdU) staining assay. The expression of MUC1 and fibrosis markers: fibronectin, collagen I, and collagen IV were assessed by western blot. In this study, we demonstrated that HG treatment induced MUC1 expression in MCs. With knockdown of MUC1 or overexpressed MUC1 in MCs, the results indicated that knockdown of MUC1 inhibited MCs proliferation and reduced kidney fibrosis markers expression, including fibronectin, collagen I, and collagen IV, whereas overexpression of MUC1 led to opposite results. Mechanically, MUC1 activated signal transducers and activators of transcription (STAT) and β-catenin signal pathway. After added AG490 (STAT inhibitor) or FH535 (β-catenin inhibitor), blocking STAT3 and β-catenin signal pathway attenuated MUC1-induced cell proliferation and fibronectin production in MCs. Finally, knockdown of MUC1 attenuated DN-induced kidney fibrosis in db/db mice. Therapeutic target for DN. In conclusion, MUC1 promotes MCs proliferation and kidney fibrosis in DN through activating STAT and β-catenin signal pathway, which can help to provide a novel therapeutic target for DN.

Glycopeptides from Paecilomyces sinensis ameliorate ethanol-induced gastric ulcers via anti-inflammation and the miR-9-5p-MEK/ERK signaling pathway

The aim of this study was to investigate the immunomodulatory effect and mechanism of the glycopeptides from Paecilomyces sinensis (CPS-II) on ethanol induced ulcers in mice. In this study, histopathological evaluation (H&E staining) and the gastric ulcer score, ulcer index, total acid secretion and gastric pH value were used to determine the anti-ulcer activity. The expression levels of interleukin (IL)-6, interleukin (IL)-10 and tumor necrosis factor-α (TNF-α) were detected by ELISA. The contents of superoxide dismutase (SOD), malondialdehyde (MDA) and epidermal growth factor (PEG2) in serum were measured according to the instructions for the reagents. Western blotting was used to detect the effect of CPS-II on the MEK/ERK pathway. The results showed that CPS-II could inhibit the ulcer score and ulcer index compared with the disease control group. CPS-II could significantly increase gastric pH and decrease gastric acid secretion in mice. The ELISA analysis showed that the expression levels of IL-6 and TNF-α in the CPS-II treatment group were significantly decreased, while the expression levels of IL-10 were significantly increased in the CPS-II treatment group. In the resveratrol treatment group, the content of MDA in serum was decreased, and the level of PEG2 and the activity of SOD in serum were significantly increased, which indicated that CPS-II has immunoregulation and anti-ulcer properties. The CPS-II treatment group could reduce the expression level of miR-9-5p in gastric tissue. pEGFR had been identified as a potential target of miR-9-5p. Western blot analysis showed that CPS-II could up-regulate the relative protein expression of pEGFR/EGFR, pRaf/Raf, pMEK/MEK, pERK/ERK, and ZO-1. The results showed that CPS-II could reduce oxidative stress and inflammatory response by regulating the miR-9-5p-MEK/ERK signaling pathway, thus protecting the gastric mucosa and improving stress gastric ulcers.

The comprehensive landscape of miR-34a in cancer research

MicroRNA-34 (miR-34) plays central roles in human diseases, especially cancers. Inactivation of miR-34 is detected in cancer cell lines and tumor tissues versus normal controls, implying its potential tumor-suppressive effect. Clinically, miR-34 has been identified as promising prognostic indicators for various cancers. In fact, members of the miR-34 family, especially miR-34a, have been convincingly proved to affect almost the whole cancer progression process. Here, a total of 512 (miR-34a, 10/21), 85 (miR-34b, 10/16), and 114 (miR-34c, 10/14) putative targets of miR-34a/b/c are predicted by at least ten miRNA databases, respectively. These targets are further analyzed in gene ontology (GO), KEGG pathway, and the Reactome pathway dataset. The results suggest their involvement in the regulation of signal transduction, macromolecule metabolism, and protein modification. Also, the targets are implicated in critical signaling pathways, such as MAPK, Notch, Wnt, PI3K/AKT, p53, and Ras, as well as apoptosis, cell cycle, and EMT-related pathways. Moreover, the upstream regulators of miR-34a, mainly including transcription factors (TFs), lncRNAs, and DNA methylation, will be summarized. Meanwhile, the potential TF upstream of miR-34a/b/c will be predicted by PROMO, JASPAR, Animal TFDB 3.0, and GeneCard databases. Notably, miR-34a is an attractive target for certain cancers. In fact, miR-34a-based systemic delivery combined with chemotherapy or radiotherapy can more effectively control tumor progression. Collectively, this review will provide a panorama for miR-34a in cancer research.

MUC3A induces PD-L1 and reduces tyrosine kinase inhibitors effects in EGFR-mutant non-small cell lung cancer

The immune checkpoint ligand programmed death-ligand 1 (PD-L1) and the transmembrane mucin (MUC) 3A are upregulated in non-small cell lung cancer (NSCLC), contributing to the aggressive pathogenesis and poor prognosis. Here, we report that knocking down the oncogenic MUC3A suppresses the PD-L1 expression in NSCLC cells. MUC3A is a potent regulator of epidermal growth factor receptor (EGFR) stability, and MUC3A deficiency downregulates the activation of the PI3K/Akt and MAPK pathways, which subsequently reduces the expression of PD-L1. Furthermore, knockdown of MUC3A and tyrosine kinase inhibitors (TKIs) in EGFR-mutant NSCLC cells play a synergistic effect on inhibited proliferation and promoted apoptosis in vitro. In the BALB/c nude mice xenograft model, MUC3A deficiency enhances EGFR-mutated NSCLC sensitivity to TKIs. Our study shows that transmembrane mucin MUC3A induces PD-L1, thereby promoting immune escape in NSCLC, while downregulation of MUC3A enhances TKIs effects in EGFR-mutant NSCLC. These findings offer insights into the design of novel combination treatment for NSCLC.

Aptamer-Gated Ion Channel for Ultrasensitive Mucin 1 Detection

Detection of cancer markers is important for early diagnosis and timely treatment of cancer. In this study, we fabricated a tailorable gold nanofilm-anodized aluminum oxide (Au-AAO) ion channel through nanoparticle self-assembly and proposed a highly sensitive and selective Mucin 1 (MUC1) detection method. By engineering the optimal layers of the Au-AAO ion channel and encoding the aptamer between the interlayers, a highly controllable ion rectification phenomenon was observed. From this, the relationship between the rectification ratio (RR) and the concentration of MUC1 was established and the highly sensitive detection of MUC1 is achieved. We found that the aptamer-modified Au-AAO ion channel has a good linear range within the MUC1 concentration of 1-10⁴ fg mL^-1 and the limit of detection (LOD) was as low as 0.0364 fg mL^-1 (0.0025 aM). Thus, this research opens a new horizon for fabricating multi-functional ion channels as well as developing ultrasensitive detection technologies.

Immunosuppressive Cell Subsets and Factors in Myeloid Leukemias

Simple Summary

Effector immune system cells have the ability to kill tumor cells. However, as a cancer (such as leukemia) develops, it inhibits and evades the effector immune response. Such a state of immunosuppression can be driven by several factors – receptors, soluble cytokines, as well as by suppressive immune cells. In this review, we describe factors and cells that constitute immunosuppressive microenvironment of myeloid leukemias. We characterize factors of direct leukemic origin, such as inhibitory receptors, enzymes and extracellular vesicles. Furthermore, we describe suppressive immune cells, such as myeloid derived suppressor cells and regulatory T cells. Finally, we sum up changes in these drivers of immune evasion in myeloid leukemias during therapy.

Abstract

Both chronic myeloid leukemia and acute myeloid leukemia evade the immune response during their development and disease progression. As myeloid leukemia cells modify their bone marrow microenvironment, they lead to dysfunction of cytotoxic cells, such as CD8+ T cells or NK cells, simultaneously promoting development of immunosuppressive regulatory T cells and suppressive myeloid cells. This facilitates disease progression, spreading of leukemic blasts outside the bone marrow niche and therapy resistance. The following review focuses on main immunosuppressive features of myeloid leukemias. Firstly, factors derived directly from leukemic cells – inhibitory receptors, soluble factors and extracellular vesicles, are described. Further, we outline function, properties and origin of main immunosuppressive cells - regulatory T cells, myeloid derived suppressor cells and macrophages. Finally, we analyze interplay between recovery of effector immunity and therapeutic modalities, such as tyrosine kinase inhibitors and chemotherapy.

MiR-200c-3p Contrasts PD-L1 Induction by Combinatorial Therapies and Slows Proliferation of Epithelial Ovarian Cancer through Downregulation of β-Catenin and c-Myc

Conventional/targeted chemotherapies and ionizing radiation (IR) are being used both as monotherapies and in combination for the treatment of epithelial ovarian cancer (EOC). Several studies show that these therapies might favor oncogenic signaling and impede anti-tumor responses. MiR-200c is considered a master regulator of EOC-related oncogenes. In this study, we sought to investigate if chemotherapy and IR could influence the expression of miR-200c-3p and its target genes, like the immune checkpoint PD-L1 and other oncogenes in a cohort of EOC patients’ biopsies. Indeed, PD-L1 expression was induced, while miR-200c-3p was significantly reduced in these biopsies post-therapy. The effect of miR-200c-3p target genes was assessed in miR-200c transfected SKOV3 cells untreated and treated with olaparib and IR alone. Under all experimental conditions, miR-200c-3p concomitantly reduced PD-L1, c-Myc and β-catenin expression and sensitized ovarian cancer cells to olaparib and irradiation. In silico analyses further confirmed the anti-correlation between miR-200c-3p with c-Myc and β-catenin in 46 OC cell lines and showed that a higher miR-200c-3p expression associates with a less tumorigenic microenvironment. These findings provide new insights into how miR-200c-3p could be used to hold in check the adverse effects of conventional chemotherapy, targeted therapy and radiation therapy, and offer a novel therapeutic strategy for EOC.

Evodiamine suppresses non-small cell lung cancer by elevating CD8+ T cells and downregulating the MUC1-C/PD-L1 axis

Background

Accumulating evidence showed that regulating tumor microenvironment plays a vital role in improving antitumor efficiency. Programmed Death Ligand 1 (PD-L1) is expressed in many cancer cell types, while its binding partner Programmed Death 1 (PD1) is expressed in activated T cells and antigen-presenting cells. Whereas, its dysregulation in the microenvironment is poorly understood. In the present study, we confirmed that evodiamine downregulates MUC1-C, resulting in modulating PD-L1 expression in non-small cell lung cancer (NSCLC).

Methods

Cell viability was measured by MTT assays. Apoptosis, cell cycle and surface PD-L1 expression on NSCLC cells were analyzed by flow cytometry. The expression of MUC1-C and PD-L1 mRNA was measured by real time RT-PCR methods. Protein expression was examined in evodiamine-treated NSCLC cells using immunoblotting or immunofluorescence assays. The effects of evodiamine treatment on NSCLC sensitivity towards T cells were investigated using human peripheral blood mononuclear cells and Jurkat, apoptosis and IL-2 secretion assays. Female H1975 xenograft nude mice were used to assess the effect of evodiamine on tumorigenesis in vivo. Lewis lung carcinoma model was used to investigate the therapeutic effects of combination evodiamine and anti-PD-1 treatment.

Results

We showed that evodiamine significantly inhibited growth, induced apoptosis and cell cycle arrest at G2 phase of NSCLC cells. Evodiamine suppressed IFN-γ-induced PD-L1 expression in H1975 and H1650. MUC1-C mRNA and protein expression were decreased by evodiamine in NSCLC cells as well. Evodiamine could downregulate the PD-L1 expression and diminish the apoptosis of T cells. It inhibited MUC1-C expression and potentiated CD8⁺ T cell effector function. Meanwhile, evodiamine showed good anti-tumor activity in H1975 tumor xenograft, which reduced tumor size. Evodiamine exhibited anti-tumor activity by elevation of CD8⁺ T cells in vivo in Lewis lung carcinoma model. Combination evodiamine and anti-PD-1 mAb treatment enhanced tumor growth control and survival of mice.

Conclusions

Evodiamine can suppress NSCLC by elevating of CD8⁺ T cells and downregulating of the MUC1-C/PD-L1 axis. Our findings uncover a novel mechanism of action of evodiamine and indicate that evodiamine represents a potential targeted agent suitable to be combined with immunotherapeutic approaches to treat NSCLC cancer patients. MUC1-C overexpression is common in female, non-smoker, patients with advanced-stage adenocarcinoma.

Supplementary Information

Supplementary information accompanies this paper at 10.1186/s13046-020-01741-5.

The Extrinsic and Intrinsic Roles of PD-L1 and Its Receptor PD-1: Implications for Immunotherapy Treatment

Programmed death-ligand 1 (PD-L1) is an immune checkpoint inhibitor that binds to its receptor PD-1 expressed by T cells and other immune cells to regulate immune responses; ultimately preventing exacerbated activation and autoimmunity. Many tumors exploit this mechanism by overexpressing PD-L1 which often correlates with poor prognosis. Some tumors have also recently been shown to express PD-1. On tumors, PD-L1 binding to PD-1 on immune cells promotes immune evasion and tumor progression, primarily by inhibition of cytotoxic T lymphocyte effector function. PD-1/PD-L1-targeted therapy has revolutionized the cancer therapy landscape and has become the first-line treatment for some cancers, due to their ability to promote durable anti-tumor immune responses in select patients with advanced cancers. Despite this clinical success, some patients have shown to be unresponsive, hyperprogressive or develop resistance to PD-1/PD-L1-targeted therapy. The exact mechanisms for this are still unclear. This review will discuss the current status of PD-1/PD-L1-targeted therapy, oncogenic expression of PD-L1, the new and emerging tumor-intrinisic roles of PD-L1 and its receptor PD-1 and how they may contribute to tumor progression and immunotherapy responses as shown in different oncology models.

Immune checkpoint inhibitors and diabetes: Mechanisms and predictors

The emergence of immune checkpoint inhibitors in the arsenal of cancer immunotherapy was a breakthrough which provided hope to many cancer patients. However, not long has passed since their discovery that some adverse effects were associated with these promising therapeutic agents. Immune checkpoint inhibitors dysregulate host immunity and may precipitate autoimmune diseases including diabetes mellitus. In this review, we go beyond the case reports towards understanding the underlying mechanisms by which Programmed cell death 1 (PD-1) and Programmed death ligand-1 (PD-L1) inhibitors precipitate diabetes. We discuss the role of PD-1/PD-L1 in autoimmunity and the use of mice models to describe their involvement in diabetes. We also reviewed the genetic anomalies in PD-1/PD-L1genes and their link to diabetes. Finally, we present the studies conducted to identify patients at risk of developing autoimmune diseases as an adverse effect for PD-1/PD-L1 use. Understanding these issues can guide researchers to find a way to circumvent the autoimmune adverse reactions seen with PD-1/PD-L1 inhibitors without affecting their antitumor activity.

Spatial and Temporal Changes in PD-L1 Expression in Cancer: The Role of Genetic Drivers, Tumor Microenvironment and Resistance to Therapy

Immunotherapies blocking immune inhibitory receptors programmed cell death-1 (PD-1) and cytotoxic T-lymphocyte-associated protein-4 (CTLA-4) on T-cells have dramatically improved patient outcomes in a range of advanced cancers. However, the lack of response, and the development of resistance remain major obstacles to long-term improvements in patient outcomes. There is significant interest in the clinical use of biomarkers to improve patient selection, and the expression of PD-1 ligand 1 (PD-L1) is often reported as a potential biomarker of response. However, accumulating evidence suggests that the predictive value of PD-L1 expression in tumor biopsies is relatively low due, in part, to its complex biology. In this review, we discuss the biological consequences of PD-L1 expression by various cell types within the tumor microenvironment, and the complex mechanisms that regulate PD-L1 expression at the genomic, transcriptomic and proteomic levels.

Ethyl Acetate Fraction from Hedyotis diffusa plus Scutellaria barbata Exerts Anti-Breast Cancer Effect via miR-200c-PDE7B/PD-L1-AKT/MAPK Axis

Background

Hedyotis diffusa (HD) Willd. and Scutellaria barbata (SB) D. Don in different ratios have been frequently used to treat various cancers in clinical Traditional Chinese Medicine prescriptions. However, the optimal ratio, active fraction, and molecular mechanisms associated with the anti-breast cancer role of this herbal couplet have not been elaborated.

Methods

To screen out the optimal ratio of this herbal couplet, we compare aqueous extracts of HD, SB, or HD plus SB in different weight ratios (HS11, HS12, HS21) for their anticancer effects on murine breast cancer 4T1 cells in vitro and in vivo. EA11, the ethyl acetate fraction from HS11 (the aqueous extract of the couplet at an equal weight ratio), is further assessed for its antiproliferative effect as well as the antitumorigenic impact with the aid of immunocompetent mice. Colony formation, flow cytometry, western blot, ELISA, and qRT-PCR are used to elucidate mechanisms underlying EA11-led effects.

Results

HS11 presents the most potential suppression of 4T1 cell proliferation and tumor growth among these aqueous extracts. The comparison results show that EA11 is more effective than HS11 in vitro and in vivo. EA11 inhibits colony formation and induces apoptosis in a concentration-dependent manner. EA11 reduces the protein expressions of PDE7B, PD-L1, β-catenin, and cyclin D1 while elevating the concentration of cellular cAMP and miR-200c expression in 4T1 cells. Additionally, EA11 exerts its anticancer effect partially via the inactivation of MAPK and AKT signaling pathways.

Conclusions

This study implicates that EA11 prevents breast tumor development by interfering with the miR-200c-PDE7B/PD-L1-AKT/MAPK axis. EA11 may represent a potential therapeutic candidate for breast cancer.

Identification of STXBP6-IRF1 positive feedback loop in regulation of PD-L1 in cancer

The clinical success of immune checkpoint blockade against diverse human cancers highlights the critical importance of insightful understanding into mechanisms underlying PD-L1 regulation. IFN-γ released by intratumoral lymphocytes regulates PD-L1 expression in tumor cells through JAK-STAT-IRF1 pathway, while the molecular events prime IRF1 to translocate into nucleus are still obscure. Here we identified STXBP6, previously recognized involving in SNARE complex assembly, negatively regulates PD-L1 transcription via retention of IRF1 in cytoplasm. IFN-γ exposure stimulates accumulation of cytosolic IRF1, which eventually saturates STXBP6 and triggers nuclear translocation of IRF1. Nuclear IRF1 in turn inhibits STXBP6 expression and thereby liberates more IRF1 to migrate to nucleus. Therefore, we identified a novel positive feedback loop between STXBP6 and IRF1 in regulation of PD-L1 expression in cancer. Furthermore, we demonstrate STXBP6 overexpression significantly inhibits T cell activation both in vitro and in vivo. These findings offer new insight into the complexity of PD-L1 expression in cancer and suggest a valuable measure to predict the response to PD-1/PD-L1-based immunotherapy.

Epigenetic Mechanisms of Resistance to Immune Checkpoint Inhibitors

Immune checkpoint inhibitors (ICIs) have demonstrated to be highly efficient in treating solid tumors; however, many patients have limited benefits in terms of response and survival. This rapidly led to the investigation of combination therapies to enhance response rates. Moreover, predictive biomarkers were assessed to better select patients. Although PD-L1 expression remains the only validated marker in clinics, molecular profiling has brought valuable information, showing that the tumor mutation load and microsatellite instability (MSI) status were associated to higher response rates in nearly all cancer types. Moreover, in lung cancer, EGFR and MET mutations, oncogene fusions or STK11 inactivating mutations were associated with low response rates. Cancer progression towards invasive phenotypes that impede immune surveillance relies on complex regulatory networks and cell interactions within the tumor microenvironment. Epigenetic modifications, such as the alteration of histone patterns, chromatin structure, DNA methylation status at specific promoters and changes in microRNA levels, may alter the cell phenotype and reshape the tumor microenvironment, allowing cells to grow and escape from immune surveillance. The objective of this review is to make an update on the identified epigenetic changes that target immune surveillance and, ultimately, ICI responses, such as histone marks, DNA methylation and miR signatures. Translational studies or clinical trials, when available, and potential epigenetic biomarkers will be discussed as perspectives in the context of combination treatment strategies to enhance ICI responses in patients with solid tumors.

Immunomodulatory role for MicroRNAs: Regulation of PD-1/PD-L1 and CTLA-4 immune checkpoints expression

The development and progression of different pathologies including, cancer, are associated with suppressed immune responses. This restrained immune activity could be associated with the activation of different immune checkpoint pathways that mediate immunosuppressive functions. Therapeutic Protocols based on abolishing the activity of immune check points provided a promising potential for treating cancer. Among the distinct known immune checkpoints, PD-1/PD-L1 and CTLA-4, are the most studied and have been the focus for development of different blocking agents. Monoclonal antibodies that can block PD-1, PD-L1 or CTLA4 have been approved for treatment of different cancers. MicroRNAs (miRNAs), short non-coding regulatory RNA molecules, could repress mRNA expression at a post-transcriptional level. Many miRNAs have been reported to modulate the expression of CTLA-4 and PD-1/PD-L1, either directly or indirectly, in multiple pathological cases, mainly cancer. In this review, after a brief introduction about T cell activation and immune checkpoints, the miRNAs regulating the expression of CTLA-4 and PD-1/PD-L1 are discussed with highlights on their role in cancer. Many of these miRNAs could serve as novel treatments in different types of cancer as detailed throughout the review.

How microRNAs affect the PD-L1 and its synthetic pathway in cancer

Programmed cell death-ligand 1 (PD-L1) is a glycoprotein that is expressed on the cell surface of both hematopoietic and nonhematopoietic cells. PD-L1 play a role in the immune tolerance and protect self-tissues from immune system attack. Dysfunction of this molecule has been highlighted in the pathogenesis of tumors, autoimmunity, and infectious disorders. MicroRNAs (miRNAs) are endogenous molecules that are classified as small non-coding RNA with approximately 20-22 nucleotides (nt) length. The function of miRNAs is based on complementary interactions with target mRNA via matching completely or incompletely. The result of this function is decay of the target mRNA or preventing mRNA translation. In the past decades, several miRNAs have been discovered which play an important role in the regulation of PD-L1 in various malignancies. In this review, we discuss the effect of miRNAs on PD-L1 expression and consider the effect of miRNAs on the synthetic pathway of PD-L1, especially during cancers.

Novel Antibodies Targeting MUC1-C Showed Anti-Metastasis and Growth-Inhibitory Effects on Human Breast Cancer Cells

Mucin1 (MUC1) is aberrantly glycosylated and overexpressed in various cancers, and it plays a crucial role in cancerogenesis. MUC1 is a type I membranous protein composed of α and β subunits. MUC1-α can be cleaved in cancers, exposing MUC1-β (MUC1-C). MUC1-C is involved with multiple cancer cellular functions, which makes it an attractive target for cancer treatment. However, its multifunctional mechanisms have not been fully elucidated and there has not been a successful therapeutic development against MUC1-C. Through a phage display process, we isolated the specific antibodies for the extracellular domain of MUC1-C. The relevant full IgG antibodies were produced successfully from mammalian cells and validated for their MUC1-C specificities through ELISA, dual FACS analysis, BLI assay, and confocal image analysis. In the comparison with reference antibody, elected antibodies showed characteristic bindings on target antigens. In the functionality assessment of high-ranking antibodies, SKM1-02, -13, and -20 antibodies highly inhibited invasion by triple-negative breast cancer (TNBC) cells and the SKM1-02 showed strong growth inhibition of cancer cells. Our results showed that these MUC1-C specific antibodies will be important tools for the understanding of MUC1 oncogenesis and are also highly effective therapeutic candidates against human breast cancers, especially TNBC cells.

The role of cancer-derived microRNAs in cancer immune escape

During malignant transformation, accumulated somatic mutations endow cancer cells with increased invasiveness and immunogenicity. Under selective pressure, these highly immunogenic cancer cells develop multiple strategies to evade immune attack. It has been well established that cancer cells could downregulate the expression of major histocompatibility complex, acquire alterations in interferon pathway, and upregulate the activities of immune checkpoint pathways. Besides, cancer cells secret numerous cytokines, exosomes, and microvesicles to regulate the functions and abundances of components in the tumor microenvironment including immune effector cells and professional antigen presentation cells. As the vital determinant of post-transcriptional regulation, microRNAs (miRNAs) not only participate in cancer initiation and progression but also regulate anti-cancer immune response. For instance, some miRNAs affect cancer immune surveillance and immune escape by interfering the expression of immune attack-associated molecules. A growing body of evidence indicated that cancer-derived immune modulatory miRNAs might be promising targets to counteract cancer immune escape. In this review, we summarized the role of some miRNAs in cancer immune escape and discussed their potential clinical application as treatment targets.

Cellular Immunotherapy for Multiple Myeloma

Cellular immunotherapy for myeloma has the unique potential both to potently kill the malignant clone and to evoke a memory response to protect from relapse. Understanding the complex interactions between the malignant clone and the microenvironment that promote immune escape is critical to evoke effective antimyeloma immunity. Tremendous progress has been made in the area of cancer vaccines and adoptive T-cell therapy in recent years. Careful study of the mechanisms of response and of immune escape will be critical to developing novel combination therapies and ultimately to improve outcomes for patients with myeloma.

Immunosuppression and Immunotargeted Therapy in Acute Myeloid Leukemia - The Potential Use of Checkpoint Inhibitors in Combination with Other Treatments

INTRODUCTION

Immunotherapy by using checkpoint inhibitors is now tried in the treatment of several malignancies, including Acute Myeloid Leukemia (AML). The treatment is tried both as monotherapy and as a part of combined therapy.

METHODS

Relevant publications were identified through literature searches in the PubMed database. We searched for (i) original articles describing the results from clinical studies of checkpoint inhibition; (ii) published articles describing the immunocompromised status of AML patients; and (iii) published studies of antileukemic immune reactivity and immunotherapy in AML.

RESULTS

Studies of monotherapy suggest that checkpoint inhibition has a modest antileukemic effect and complete hematological remissions are uncommon, whereas combination with conventional chemotherapy increases the antileukemic efficiency with acceptable toxicity. The experience with a combination of different checkpoint inhibitors is limited. Thalidomide derivatives are referred to as immunomodulatory drugs and seem to reverse leukemia-induced immunosuppression, but in addition, they have direct inhibitory effects on the AML cells. The combination of checkpoint targeting and thalidomide derivatives thus represents a strategy for dual immunotargeting together with a direct antileukemic effect.

CONCLUSION

Checkpoint inhibitors are now tried in AML. Experimental studies suggest that these inhibitors should be combined with immunomodulatory agents (i.e. thalidomide derivatives) and/or new targeted or conventional antileukemic treatment. Such combinations would allow dual immunotargeting (checkpoint inhibitor, immunomodulatory agents) together with a double/triple direct targeting of the leukemic cells.

Regulation of PD-1/PD-L1 Pathway in Cancer by Noncoding RNAs

Immune checkpoint blockade has demonstrated significant anti-tumor immunity in an array of cancer types, yet the underlying regulatory mechanism of it is still obscure, and many problems remain to be solved. As an inhibitory costimulatory signal of T-cells, the programmed cell death 1 (PD-1)/programmed cell death ligand 1 (PD-L1) pathway can paralyze T-cells at the tumor site, enabling the immune escape of tumor cells. Although many antibodies targeting PD-1/PD-L1 have been developed to block their interaction for the treatment of cancer, the reduced response rate and resistance to the therapies call for further comprehension of this pathway in the tumor microenvironment. MicroRNAs (miRNAs) and long noncoding RNAs (lncRNAs) are two main types of noncoding RNAs that play critical parts in the regulation of immune response in tumorigenesis, including the PD-1/PD-L1 pathway. Here we summarize the most recent studies on the control of this pathway by noncoding RNAs in cancer and hopefully will offer new insights into immune checkpoint blockade therapies.

Noncoding RNAs as potential mediators of resistance to cancer immunotherapy

Substantial evolution in cancer therapy has been witnessed lately, steering mainly towards immunotherapeutic approaches, replacing or in combination with classical therapies. Whereas the use of various immunotherapy approaches, such as adoptive T cell therapy, genetically-modified T cells, or immune checkpoint inhibitors, has been a triumph for cancer immunotherapy, the great challenge is the ability of the immune system to sustain long lasting anti-tumor response. Additionally, epigenetic changes in a suppressive tumor microenvironment can pertain to T cell exhaustion, limiting their functionality. Noncoding RNAs (ncRNAs) have emerged over the last years as key players in epigenetic regulation. Among those, microRNAs (miRNAs) and long noncoding RNAs (lncRNAs) have been studied extensively for their potential role in regulating tumor immunity through direct regulation of genes involved in immune activation or suppression. In this review, we will provide an overview of contemporary approaches for cancer immunotherapy and will present the current state of knowledge implicating miRNAs and lncRNAs in regulating immune response against human cancer and their potential implications in resistance to cancer immunotherapy, with main emphasis on immune checkpoints regulation.

Recent Findings in the Regulation of Programmed Death Ligand 1 Expression

With the recent approvals for the application of monoclonal antibodies that target the well-characterized immune checkpoints, immune therapy shows great potential against both solid and hematologic tumors. The use of these therapeutic monoclonal antibodies elicits inspiring clinical results with durable objective responses and improvements in overall survival. Agents targeting programmed cell death protein 1 (PD-1; also known as PDCD1) and its ligand (PD-L1) achieve a great success in immune checkpoints therapy. However, the majority of patients fail to respond to PD-1/PD-L1 axis inhibitors. Expression of PD-L1 on the membrane of tumor and immune cells has been shown to be associated with enhanced objective response rates to PD-1/PD-L1 inhibition. Thus, an improved understanding of how PD-L1 expression is regulated will enable us to better define its role as a predictive marker. In this review, we summarize recent findings in the regulation of PD-L1 expression.

Role of microRNAs, circRNAs and long noncoding RNAs in acute myeloid leukemia

Acute myeloid leukemia (AML) is a malignant tumor of the immature myeloid hematopoietic cells in the bone marrow (BM). It is a highly heterogeneous disease, with rising morbidity and mortality in older patients. Although researches over the past decades have improved our understanding of AML, its pathogenesis has not yet been fully elucidated. Long noncoding RNAs (lncRNAs), microRNAs (miRNAs), and circular RNAs (circRNAs) are three noncoding RNA (ncRNA) molecules that regulate DNA transcription and translation. With the development of RNA-Seq technology, more and more ncRNAs that are closely related to AML leukemogenesis have been discovered. Numerous studies have found that these ncRNAs play an important role in leukemia cell proliferation, differentiation, and apoptosis. Some may potentially be used as prognostic biomarkers. In this systematic review, we briefly described the characteristics and molecular functions of three groups of ncRNAs, including lncRNAs, miRNAs, and circRNAs, and discussed their relationships with AML in detail.

Diagnostic and therapeutic applications of miRNA-based strategies to cancer immunotherapy

Cancer immunotherapy has shown impressive clinical results in the last decade, improving both solid and hematologic cancer patients' overall survival. Nevertheless, most of the molecular aspects underlying the response to this approach are still under investigation. miRNAs in particular have been described as regulators of a plethora of different immunologic processes and thus have the potential to be key in the future developments of immunotherapy. In this review, we summarize and discuss the emerging role of miRNAs in the diagnosis and therapeutics of the four principal cancer immunotherapy approaches: immune checkpoint blockade, adoptive cell therapy, cancer vaccines, and cytokine therapy. In particular, this review is focused on potential roles for miRNAs to be adjuvants in soluble factor- and cell-based therapies, with the aim of helping to increase specificity and decrease toxicity, and on the potential for rationally identified miRNA-based diagnostic approaches to aid in precision clinical immunooncology.

Management of AML Beyond "3 + 7" in 2019

The therapeutic paradigm for treatment of acute myeloid leukemia (AML) is rapidly changing with the advent of a new generation of drugs targeting diverse aspects of leukemogenesis. Whereas standard treatment for AML until recently consisted of a classic chemotherapy backbone, the incorporation of novel agents targeting pathogenic mutations, myeloid surface markers, and apoptosis-related proteins may become a reality in the next few years. In this review, we outline the therapeutic landscape of recently approved novel agents for AML, including FLT3 inhibitors, isocitrate dehydrogenase 1/2 (IDH1/2) inhibitors, Bcl-2 antagonists, hedgehog signaling inhibitors, and immunotherapy-based approaches. Some of the future challenges in the field would be to delineate which specific patient subsets derive the most clinical benefit from a given novel agent and, furthermore, which drug combinations will yield the maximal antileukemia effect without increased toxicity. To this end, it is expected that advances in genomic and epigenomic classification of AML will facilitate a rational and optimal choice of these novel agents for AML patients.

Viral loads correlate with upregulation of PD-L1 and worse patient prognosis in Epstein-Barr Virus-associated gastric carcinoma

Epstein–Barr virus (EBV)-associated gastric carcinoma (EBVaGC), one of four major gastric cancer types, consists of clonal growth of EBV-infected epithelial cells. However, the significance of viral loads in each tumor cell has not been evaluated. EBV-DNA is stably maintained in episomal form in the nucleus of each cancer cell. To estimate EBV copy number per genome (EBV-CN), qPCR of viral EBNA1 and host GAPDH, standardized by Namalwa DNA (one copy/genome), was applied to the formalin-fixed paraffin embedded (FFPE) surgically resected EBVaGC specimens (n = 43) and EBVaGC cell lines (SNU-719 and NCC-24). In surgical specimens, the cancer cell ratio (CCR) was determined with image analysis, and EBV-CN was obtained by adjusting qPCR value with CCR. Fluorescent in situ hybridization (FISH) was also applied to the FFPE sections using the whole EBV-genome as a probe. In surgical specimens, EBV-CN obtained by qPCR/CCR was between 1.2 and 185 copies with a median of 9.9. EBV-CN of SNU-719 and NCC-24 was 42.0 and 1.1, respectively. A linear correlation was observed with qPCR/CCR data up to 20 copies/genome (40 signals/nucleus), the limit of FISH analysis. In addition, substantial variation in the number of EBV foci was observed. Based on qPCR/CCR, high EBV-CN (>10 copies) correlated with PD-L1 expression in cancer cells (P = 0.015), but not with other pathological indicators. Furthermore, EBVaGC with high EBV-CN showed worse disease-specific survival (P = 0.041). Our findings suggest that cancer cell viral loads may contribute to expression of the immune checkpoint molecule and promotion of cancer progression in EBVaGC.

Upregulation of PD-L1 predicts poor prognosis and is associated with miR-191-5p dysregulation in colon adenocarcinoma

Targeting of the programmed cell-death 1 ligand 1 (PD-L1) signal pathway is a promising treatment strategy in several cancers. The purpose of this study was to evaluate the clinical significance of PD-L1 in patients with colon adenocarcinoma (COAD). A total of 240 patients who were diagnosed with COAD from The Cancer Genome Atlas (TCGA) RNA-sequencing data and another cohort for pair-matched COAD samples (n = 40) in tissue microarray (TMA) were enrolled in this study. The correlation of PD-L1 or miR-191-5p expression with clinicopathological features and prognosis in patients with COAD was further analyzed using TCGA data and TMA. The Cox proportional hazard regression model was used to evaluate the association of PD-L1 or miR-191-5p expression with overall survival (OS) and tumor recurrence in patients with COAD. The microRNAs (miRNAs) that target PD-L1 gene were identified by bioinformatics and Spearman correlation analysis. We found that PD-L1 expression was increased in COAD tissues and was correlated with poor survival and tumor recurrence in patients with COAD. The increased expression of PD-L1 was attributed to the dysregulation of miR-191-5p expression rather than its genetic or epigenetic alterations. Moreover, the expression of miR-191-5p presented the negative correlation with PD-L1 expression and acted as an independent prognostic factor of OS in patients with COAD. Therefore, PD-L1 may predict poor prognosis and is negatively associated with miR-191-5p expression in patients with COAD.

Epigenetic regulators of programmed death-ligand 1 expression in human cancers

The programmed cell death protein 1-programmed death-ligand 1 (PD-L1) axis has been successfully targeted in clinics and the use of immune check-point inhibitors have shown durable antitumor response in untreated or heavily treated advanced stage cancer. PD-L1 upregulation has been found to correlate with poor prognosis in multiple cancer types and expression of PD-L1 in intratumoral compartment has been suggested to influence immune response and act as a key determinant of checkpoint immunotherapy efficacy. Hence it becomes critical to understand the regulation of PD-L1 expression in cancer. Role of oncogenic signaling pathways and transcription factors such as PI3K-AKT, MEK-ERK, JAK-STAT, MYC, HIF-1α, AP-1 and NF-κB is well established in inducing PD-L1 expression. Even the structural variations resulting in the truncation of the 3' untranslated region (UTR) of PD-L1 has been shown to upregulate PD-L1 expression in multiple cancer types. Since microRNAs carry out post-transcriptional gene silencing by binding to the 3' UTR of its target messenger RNA, truncation of PD-L1 3' UTR can result in alleviation of PD-L1 suppression mediated by microRNA, leading to its overexpression. Other epigenetic modifications, such as promoter DNA methylation and histone modifications can also play crucial role in regulating PD-L1 expression. Here, we review recent findings and evidence on epigenetic mechanisms that regulate PD-L1 expression and the biological and clinical implications of such regulation in cancer.

Biochemical Aspects of PD-L1 Regulation in Cancer Immunotherapy

PD-L1, frequently expressed in human cancers, engages with PD-1 on immune cells and contributes to cancer immune evasion. As such, antibodies blocking the PD-1/PD-L1 interaction reactivate cytotoxic T cells to eradicate cancer cells. However, a majority of cancer patients fail to respond to PD-1/PD-L1 blockade with unclear underlying mechanism(s). Recent studies revealed that PD-L1 expression levels on tumor cells might affect the clinical response to anti-PD-1/PD-L1 therapies. Hence, understanding molecular mechanisms for controlling PD-L1 expression will be important to improve the clinical response rate and efficacy of PD-1/PD-L1 blockade. In this review, we primarily focus on summarizing PD-L1 regulation and its potential roles in regulating antitumor immune response, with purpose to optimize anti-PD-1/PD-L1 therapies, benefiting a wider cancer patient population.

Tumor-Intrinsic PD-L1 Signaling in Cancer Initiation, Development and Treatment: Beyond Immune Evasion

Although the role of PD-L1 in suppressing the anti-tumor immune response is extensively documented, recent discoveries indicate a distinct tumor-intrinsic role for PD-L1 in modulating epithelial-to-mesenchymal transition (EMT), cancer stem cell (CSC)-like phenotype, metastasis and resistance to therapy. In this review, we will focus on the newly discovered functions of PD-L1 in the regulation of cancer development, describe underlying molecular mechanisms responsible for PD-L1 upregulation and discuss current insights into novel components of PD-L1 signaling. Furthermore, we summarize our current understanding of the link between PD-L1 signaling and the EMT program as well as the CSC state. Tumor cell-intrinsic PD-L1 clearly contributes to cancer stemness, EMT, tumor invasion and chemoresistance in multiple tumor types. Conversely, activation of OCT4 signaling and upregulation of EMT inducer ZEB1 induce PD-L1 expression in cancer cells, thereby suggesting a possible immune evasion mechanism employed by cancer stem cells during metastasis. Our meta-analysis demonstrated that PD-L1 is co-amplified along with MYC, SOX2, N-cadherin and SNAI1 in the TCGA endometrial and ovarian cancer datasets. Further identification of immune-independent PD-L1 functions and characterization of crucial signaling events upstream or downstream of PD-L1 in diverse cancer types and specific cancer subtypes, would provide additional targets and new therapeutic approaches.

The Nefarious Nexus of Noncoding RNAs in Cancer

The past decade has witnessed enormous progress, and has seen the noncoding RNAs (ncRNAs) turn from the so-called dark matter RNA to critical functional molecules, influencing most physiological processes in development and disease contexts. Many ncRNAs interact with each other and are part of networks that influence the cell transcriptome and proteome and consequently the outcome of biological processes. The regulatory circuits controlled by ncRNAs have become increasingly more relevant in cancer. Further understanding of these complex network interactions and how ncRNAs are regulated, is paving the way for the identification of better therapeutic strategies in cancer.

Epstein-Barr virus-encoded EBNA2 alters immune checkpoint PD-L1 expression by downregulating miR-34a in B-cell lymphomas

Cancer cells subvert host immune surveillance by altering immune checkpoint (IC) proteins. Some Epstein−Barr virus (EBV)-associated tumors have higher Programmed Cell Death Ligand, PD-L1 expression. However, it is not known how EBV alters ICs in the context of its preferred host, the B lymphocyte and in derived lymphomas. Here, we found that latency III-expressing Burkitt lymphoma (BL), diffuse large B-cell lymphomas (DLBCL) or their EBNA2-transfected derivatives express high PD-L1. In a DLBCL model, EBNA2 but not LMP1 is sufficient to induce PD-L1. Latency III-expressing DLBCL biopsies showed high levels of PD-L1. The PD-L1 targeting oncosuppressor microRNA miR-34a was downregulated in EBNA2-transfected lymphoma cells. We identified early B-cell factor 1 (EBF1) as a repressor of miR-34a transcription. Short hairpin RNA (shRNA)-mediated knockdown of EBF1 was sufficient to induce miR-34a transcription, which in turn reduced PD-L1. MiR-34a reconstitution in EBNA2-transfected DLBCL reduced PD-L1 expression and increased its immunogenicity in mixed lymphocyte reactions (MLR) and in three-dimensional biomimetic microfluidic chips. Given the importance of PD-L1 inhibition in immunotherapy and miR-34a dysregulation in cancers, our findings may have important implications for combinatorial immunotherapy, which include IC inhibiting antibodies and miR-34a, for EBV-associated cancers.

Using microRNA Networks to Understand Cancer

Human cancers are characterized by deregulated expression of multiple microRNAs (miRNAs), involved in essential pathways that confer the malignant cells their tumorigenic potential. Each miRNA can regulate hundreds of messenger RNAs (mRNAs), while various miRNAs can control the same mRNA. Additionally, many miRNAs regulate and are regulated by other species of non-coding RNAs, such as circular RNAs (circRNAs) and long non-coding RNAs (lncRNAs). For this reason, it is extremely difficult to predict, study, and analyze the precise role of a single miRNA involved in human cancer, considering the complexity of its connections. Focusing on a single miRNA molecule represents a limited approach. Additional information could come from network analysis, which has become a common tool in the biological field to better understand molecular interactions. In this review, we focus on the main types of networks (monopartite, association networks and bipartite) used for analyzing biological data related to miRNA function. We briefly present the important steps to take when generating networks, illustrating the theory with published examples and with future perspectives of how this approach can help to better select miRNAs that can be therapeutically targeted in cancer.

Latest developments in MUC1 immunotherapy

Currently, there is renewed interest in attempting to recruit the host immune system to eliminate cancers, and within this renewed activity, MUC1 continues to arouse interest. MUC1 has been considered a possible therapeutic target for the past 30 years as it is up-regulated, aberrantly glycosylated and its polarization is lost in many adenocarcinomas. Moreover, MUC1 is expressed by some haematopoietic cancers, including acute myeloid leukaemia and myeloma. Although multiple clinical trials have been initiated and immune responses have been documented, effective clinical benefit worthy of approval for general application has not as yet been achieved. However, this does not appear to have quelled the interest in MUC1 as a therapeutic target, as shown by the increase in the number of MUC1-based clinical trials initiated in 2017 ( Figure 1). As with all translational studies, incorporating new relevant research findings into therapeutic strategy is difficult. Decisions are made to commit to a specific strategy based on the information and data available when the trial is initiated. However, the time required for preclinical studies and early trials can render the founding concept not always appropriate for proceeding to a larger definitive trial. Here, we summarize the attempts made, to date, to bring MUC1 into the world of cancer immunotherapy and discuss how research findings regarding MUC1 structure and function together with expanded knowledge of its interactions with the tumour environment and immune effector cells could lead to improved therapeutic approaches. ppbiost;46/3/659/BST20170400CF1F1BST-2017-0400CF1Figure 1.Number of MUC1-targeted trials initiated each year.

Clinical Significance of PTEN Deletion, Mutation, and Loss of PTEN Expression in De Novo Diffuse Large B-Cell Lymphoma

PTEN loss has been associated with poorer prognosis in many solid tumors. However, such investigation in lymphomas is limited. In this study, PTEN cytoplasmic and nuclear expression, PTEN gene deletion, and PTEN mutations were evaluated in two independent cohorts of diffuse large B-cell lymphoma (DLBCL). Cytoplasmic PTEN expression was found in approximately 67% of total 747 DLBCL cases, more frequently in the activated B-cell–like subtype. Nuclear PTEN expression was less frequent and at lower levels, which significantly correlated with higher PTEN mRNA expression. Remarkably, loss of PTEN protein expression was associated with poorer survival only in DLBCL with AKT hyperactivation. In contrast, high PTEN expression was associated with Myc expression and poorer survival in cases without abnormal AKT activation. Genetic and epigenetic mechanisms for loss of PTEN expression were investigated. PTEN deletions (mostly heterozygous) were detected in 11.3% of DLBCL, and showed opposite prognostic effects in patients with AKT hyperactivation and in MYC rearranged DLBCL patients. PTEN mutations, detected in 10.6% of patients, were associated with upregulation of genes involved in central nervous system function, metabolism, and AKT/mTOR signaling regulation. Loss of PTEN cytoplasmic expression was also associated with TP53 mutations, higher PTEN-targeting microRNA expression, and lower PD-L1 expression. Remarkably, low PTEN mRNA expression was associated with down-regulation of a group of genes involved in immune responses and B-cell development/differentiation, and poorer survival in DLBCL independent of AKT activation. Collectively, multi-levels of PTEN abnormalities and dysregulation may play important roles in PTEN expression and loss, and that loss of PTEN tumor-suppressor function contributes to the poor survival of DLBCL patients with AKT hyperactivation.

Key questions about the checkpoint blockade-are microRNAs an answer?

The introduction of immune-checkpoint blockade in the cancer therapy led to a paradigm change of the management of late stage cancers. There are already multiple FDA approved checkpoint inhibitors and many other agents are undergoing phase 2 and early phase 3 clinical trials. The therapeutic indication of immune checkpoint inhibitors expanded in the last years, but still remains unclear who can benefit. MicroRNAs are small RNAs with no coding potential. By complementary pairing to the 3' untranslated region of messenger RNA, microRNAs exert posttranscriptional control of protein expression. A network of microRNAs directly and indirectly controls the expression of checkpoint receptors and several microRNAs can target multiple checkpoint molecules, mimicking the therapeutic effect of a combined immune checkpoint blockade. In this review, we will describe the microRNAs that control the expression of immune checkpoints and we will present four specific issues of the immune checkpoint therapy in cancer: (1) imprecise therapeutic indication, (2) difficult response evaluation, (3) numerous immunologic adverse-events, and (4) the absence of response to immune therapy. Finally, we propose microRNAs as possible solutions for these pitfalls. We consider that in the near future microRNAs could become important therapeutic partners of the immune checkpoint therapy.