AKT-STAT3 Pathway as a Downstream Target of EGFR Signaling to Regulate PD-L1 Expression on NSCLC cells

Probing phosphorylation events in biological membranes: The transducer function

The extracellular environment is sensed by receptors in the plasma membrane. Some of these receptors initiate cytoplasmic signaling cascades involving phosphorylation: the addition of a phosphate group to a specific amino acid, such as tyrosine, in a protein. Receptor Tyrosine Kinases (RTKs) are one large class of membrane receptors that can directly initiate signaling cascades through their intracellular kinase domains, which both catalyze tyrosine phosphorylation and get phosphorylated. In the first step of signaling, the ligands stabilize phosphorylation-competent RTK dimers and oligomers, which leads to the phosphorylation of specific tyrosine residues in the activation loop of the kinases. Here we discuss quantitative measurements of tyrosine phosphorylation efficiencies for RTKs, described by the "transducer function". The transducer function links the phosphorylation (the response) and the binding of the activating ligand to the receptor (the stimulus). We overview a methodology that allows such measurements in direct response to ligand binding. We discuss experiments which demonstrate that EGF is a partial agonist, and that two tyrosines in the intracellular domain of EGFR, Y1068 and Y1173, are differentially phosphorylated in the EGF-bound EGFR dimers.

Advances in dual-targeting inhibitors of HDAC6 for cancer treatment

Histone Deacetylase 6 (HDAC6) is an essential regulator of histone acetylation processes, exerting influence on a multitude of cellular functions such as cell motility, endocytosis, autophagy, apoptosis, and protein trafficking through its deacetylation activity. The significant implications of HDAC6 in diseases such as cancer, neurodegenerative disorders, and immune disorders have motivated extensive investigation into the development of specific inhibitors targeting this enzyme for therapeutic purposes. Single targeting drugs carry the risk of inducing drug resistance, thus prompting exploration of dual targeting therapy which offers the potential to impact multiple signaling pathways simultaneously, thereby lowering the likelihood of resistance development. While pharmacological studies have exhibited promise in combined therapy involving HDAC6, challenges related to potential drug interactions exist. In response to these challenges, researchers are investigating HDAC6 hybrid molecules which enable the concomitant targeting of HDAC6 and other key proteins, thus enhancing treatment efficacy while mitigating side effects and reducing the risk of resistance compared to traditional combination therapies. The published design strategies for dual targeting inhibitors of HDAC6 are summarized and discussed in this review. This will provide some valuable insights into more novel HDAC6 dual targeting inhibitors to meet the urgent need for innovative therapies in oncology and other related fields.

Impact of PD-L1 Expression on the Overall Survival of Caucasian Patients with Advanced EGFR-Mutant NSCLC Treated with Frontline Osimertinib

BACKGROUND

The treatment of advanced non-small cell lung cancer (NSCLC) harboring an oncogenic epidermal growth factor receptor mutation (EGFRm) is currently based on osimertinib, a third-generation tyrosine kinase inhibitor (TKI). High Programmed death ligand 1 (PD-L1) expression ≥ 50% demonstrated to be a negative prognostic factor, mostly among Asian populations treated with 1st/2nd generation TKI.

OBJECTIVE

We investigated the impact of PD-L1 expression on the progression free survival (PFS) and overall survival (OS) within a cohort of patients receiving osimertinib as first-line treatment.

METHODS

Our bi-centre French retrospective study included all newly diagnosed patients with an advanced EGFRm (common and uncommon) NSCLC, between May 2018 and November 2022, treated with osimertinib. The primary endpoint was OS according to tumor proportion score PD-L1 expression (low/intermediate < 50% vs high ≥ 50%). Survival analyses were performed using Kaplan-Meier method and Cox model for adjusted multivariate analysis.

RESULTS

Of 96 patients, median age was 71 (IQR 62-76), 70 were women (72.9%), 81 had a performance status (PS) 0-1 (84.3%). Median follow-up was 22.6 months (95% CI 20.5-24.7). Twenty patients (20.8%) had high PD-L1 expression ≥ 50%. No significant differences in baseline characteristics were observed based on PD-L1 status. Patients with PD-L1 ≥ 50% had significant shorter PFS and OS than those with PD-L1 < 50%, respectively 9.3 vs 17.5 months (p = 0.044 months) and 14.3 vs 26.0 months (p = 0.025). Multivariable adjustment for baseline characteristics found that PS ≥ 2 (HR 2.79, 95% CI 1.12-6.93, p = 0.027), PD-L1 ≥ 50% (HR 2.61, 95% CI 1.31 to 5.22, p = 0.007) and uncommon EGFR mutation (HR 4.59, 95% CI 1.95-10.80, p = <0.001) were associated with a shorter OS. Brain metastases at diagnosis and age ≥ 65 were not, respectively HR 1.66 (95% CI 0.90-3.06, p = 0.11) and HR 0.95 (95% CI 0.50-1.80, p=0.9).

CONCLUSIONS

Our study found that PD-L1 expression ≥ 50% was associated with a shorter OS in EGFRm NSCLC patients treated with first line osimertinib. Further research is warranted to understand the underlying molecular and cellular mechanisms of this correlation.

From immune checkpoints to therapies: understanding immune checkpoint regulation and the influence of natural products and traditional medicine on immune checkpoint and immunotherapy in lung cancer

Lung cancer is a disease of global concern, and immunotherapy has brought lung cancer therapy to a new era. Besides promising effects in the clinical use of immune checkpoint inhibitors, immune-related adverse events (irAEs) and low response rates are problems unsolved. Natural products and traditional medicine with an immune-modulating nature have the property to influence immune checkpoint expression and can improve immunotherapy's effect with relatively low toxicity. This review summarizes currently approved immunotherapy and the current mechanisms known to regulate immune checkpoint expression in lung cancer. It lists natural products and traditional medicine capable of influencing immune checkpoints or synergizing with immunotherapy in lung cancer, exploring both their effects and underlying mechanisms. Future research on immune checkpoint modulation and immunotherapy combination applying natural products and traditional medicine will be based on a deeper understanding of their mechanisms regulating immune checkpoints. Continued exploration of natural products and traditional medicine holds the potential to enhance the efficacy and reduce the adverse reactions of immunotherapy.

Comprehensive exploration of Biochanin A as an oncotherapeutics potential in the treatment of multivarious cancers with molecular insights

Cancer is considered a leading cause of mortality. This rising cancer death rate and several existing limitations like side effects, poor efficacies, and high cost of the present chemotherapeutic agents have increased the demand for more potent and alternative cancer treatments. This review elucidated a brief overview of Biochanin A (BCA) and its potentiality on various cancers with details of anticancer mechanism. According to our review, a number of studies including in silico, in vitro, pre-clinical, and clinical trials have tested to evaluate the efficacy of BCA. This compound is effective against 15 types of cancer, including breast, cervical, colorectal, gastric, glioblastoma, liver, lung, melanoma, oral, osteosarcoma, ovarian, pancreatic, pharynx, prostate, and umbilical vein cancer. The general anticancer activities of this compound are mediated via several molecular processes, including regulation of apoptosis, cell proliferation, metastasis and angiogenesis, signaling, enzymatic pathways, and other mechanisms. Targeting both therapeutic and oncogenic proteins, as well as different pathways, makes up the molecular mechanism underlying the anticancer action. Many signaling networks and their components, such as EFGR, PI3K/Akt/mTOR, MAPK, MMP-2, MMP-9, PARP, Caspase-3/8/9, Bax, Bcl2, PDL-1, NF-κB, TNF-α, IL-6, JAK, STAT3, VEGFR, VEGF, c-MY, Cyclin B1, D1, E1 and CDKs, Snail, and E-cadherin proteins, can be regulated in cancer cells by BCA. Such kind of anticancer properties of BCA could be a result of its correct structural chemistry. The use of BCA-based therapies as nano-carriers for the delivery of chemotherapeutic medicines has the potential to be very effective. This natural compound synergises with other natural compounds and standard drugs, including sorafenib, 5-fluorouracil, temozolomide, doxorubicin, apigenin, and genistein. Moreover, proper use of this compound can reverse multidrug resistance through numerous mechanisms. BCA has better drug-likeness and pharmacokinetic properties and is nontoxic (eye, liver, kidney, skin, cardio) in human bodies. As having a wide range of cancer-fighting mechanisms, synergistic effects, and good pharmacokinetic properties, BCA can be used as a supplementary food until standard drugs are available at pharma markets.

Interfering with the AKT/mTOR/STAT3/ID1 signaling axis with usenamine A restrains the proliferative and invasive potential of human hepatocellular carcinoma cells

BACKGROUND

Usenamine A, a novel natural compound initially isolated from the lichen Usnea longissima, has exhibited promising efficacy against hepatoma in prior investigation. Nevertheless, the underlying mechanisms responsible for its antihepatoma effects remain unclear. Furthermore, the role of the AKT/mechanistic target of the rapamycin (mTOR)/signal transducer and activator of transcription 3 (STAT3)/inhibitor of differentiation/DNA binding 1 (ID1) signaling axis in hepatocellular carcinoma (HCC), and the potential anti-HCC effects of drugs targeting this pathway are not well understood.

METHODS

CCK-8 assay was used to investigate the effects of usenamine A on the proliferation of human HCC cells. Moreover, the effects of usenamine A on the invasion ability of human HCC cells were evaluated by transwell assay. In addition, expression profiling analysis, quantitative real-time PCR, immunoblotting, immunohistochemistry (IHC) analysis, RNAi, immunoprecipitation, and chromatin immunoprecipitation (ChIP) assay were used to explore the effects of usenamine A on the newly identified AKT/mTOR/STAT3/ID1 signaling axis in human HCC cells.

RESULTS

Usenamine A inhibited the proliferation and invasion of human HCC cell lines (HepG2 and SK-HEP-1). Through the analysis of gene expression profiling, we identified that usenamine A suppressed the expression of ID1 in human HCC cells. Furthermore, immunoprecipitation experiments revealed that usenamine A facilitated the degradation of the ID1 protein via the ubiquitin-proteasome pathway. Moreover, usenamine A inhibited the activity of STAT3 in human HCC cells. ChIP analysis demonstrated that STAT3 positively regulated ID1 expression at the transcriptional level in human HCC cells. The STAT3/ID1 axis played a role in mediating the anti-proliferative and anti-invasive impacts of usenamine A on human HCC cells. Additionally, usenamine A suppressed the STAT3/ID1 axis through AKT/mTOR signaling in human HCC cells.

CONCLUSION

Usenamine A displayed robust anti-HCC potential, partly attributed to its capacity to downregulate the AKT/mTOR/STAT3/ID1 signaling pathway and promote ubiquitin-proteasome-mediated ID1 degradation. Usenamine A has the potential to be developed as a therapeutic agent for HCC cases characterized by abnormal AKT/mTOR/STAT3/ID1 signaling, and targeting the AKT/mTOR/STAT3 signaling pathway may be a viable option for treating patients with HCC exhibiting elevated ID1 expression.

Opaganib (ABC294640) Induces Immunogenic Tumor Cell Death and Enhances Checkpoint Antibody Therapy

Antibody-based cancer drugs that target the checkpoint proteins CTLA-4, PD-1 and PD-L1 provide marked improvement in some patients with deadly diseases such as lung cancer and melanoma. However, most patients are either unresponsive or relapse following an initial response, underscoring the need for further improvement in immunotherapy. Certain drugs induce immunogenic cell death (ICD) in tumor cells in which the dying cells promote immunologic responses in the host that may enhance the in vivo activity of checkpoint antibodies. Sphingolipid metabolism is a key pathway in cancer biology, in which ceramides and sphingosine 1-phosphate (S1P) regulate tumor cell death, proliferation and drug resistance, as well as host inflammation and immunity. In particular, sphingosine kinases are key sites for manipulation of the ceramide/S1P balance that regulates tumor cell proliferation and sensitivity to radiation and chemotherapy. We and others have demonstrated that inhibition of sphingosine kinase-2 by the small-molecule investigational drug opaganib (formerly ABC294640) kills tumor cells and increases their sensitivities to other drugs and radiation. Because sphingolipids have been shown to regulate ICD, opaganib may induce ICD and improve the efficacy of checkpoint antibodies for cancer therapy. This was demonstrated by showing that in vitro treatment with opaganib increases the surface expression of the ICD marker calreticulin on a variety of tumor cell types. In vivo confirmation was achieved using the gold standard immunization assay in which B16 melanoma, Lewis lung carcinoma (LLC) or Neuro-2a neuroblastoma cells were treated with opaganib in vitro and then injected subcutaneously into syngeneic mice, followed by implantation of untreated tumor cells 7 days later. In all cases, immunization with opaganib-treated cells strongly suppressed the growth of subsequently injected tumor cells. Interestingly, opaganib treatment induced crossover immunity in that opaganib-treated B16 cells suppressed the growth of both untreated B16 and LLC cells and opaganib-treated LLC cells inhibited the growth of both untreated LLC and B16 cells. Next, the effects of opaganib in combination with a checkpoint antibody on tumor growth in vivo were assessed. Opaganib and anti-PD-1 antibody each slowed the growth of B16 tumors and improved mouse survival, while the combination of opaganib plus anti-PD-1 strongly suppressed tumor growth and improved survival (p < 0.0001). Individually, opaganib and anti-CTLA-4 antibody had modest effects on the growth of LLC tumors and mouse survival, whereas the combination of opaganib with anti-CTLA-4 substantially inhibited tumor growth and increased survival (p < 0.001). Finally, the survival of mice bearing B16 tumors was only marginally improved by opaganib or anti-PD-L1 antibody alone but was nearly doubled by the drugs in combination (p < 0.005). Overall, these studies demonstrate the ability of opaganib to induce ICD in tumor cells, which improves the antitumor activity of checkpoint antibodies.

Quantification of ligand and mutation-induced bias in EGFR phosphorylation in direct response to ligand binding

Signaling bias is the ability of a receptor to differentially activate downstream signaling pathways in response to different ligands. Bias investigations have been hindered by inconsistent results in different cellular contexts. Here we introduce a methodology to identify and quantify bias in signal transduction across the plasma membrane without contributions from feedback loops and system bias. We apply the methodology to quantify phosphorylation efficiencies and determine absolute bias coefficients. We show that the signaling of epidermal growth factor receptor (EGFR) to EGF and TGFα is biased towards Y1068 and against Y1173 phosphorylation, but has no bias for epiregulin. We further show that the L834R mutation found in non-small-cell lung cancer induces signaling bias as it switches the preferences to Y1173 phosphorylation. The knowledge gained here challenges the current understanding of EGFR signaling in health and disease and opens avenues for the exploration of biased inhibitors as anti-cancer therapies.

Bakuchiol inhibits lung cancer by modulating tumor microenvironment and the expression of PD-L1

Immune checkpoint therapy is an emerging frontier in cancer therapy. With the aim to develop an efficient herb derived compound to facilitate immune checkpoint therapy, here we investigate if a herb-derived compound, Bakuchiol (BAK), can be used to treat lung cancer and elucidate if BAK could serve as a PD-L1 regulator. To this end, a murine lung cancer model was established by subcutaneously inoculating murine Lewis lung carcinoma (LLC) cells. BAK of 5 to 40 mg/kg was used for treatment in vivo for 15 days. On Day 15, the population of CD4+ and CD8+ T cells, Treg cells. BAK could effectively inhibit tumor growth by starting treatment either on Day 0 or 6 after tumor inoculation at doses of 5-40 mg/kg. BAK treatment increased the population of cytotoxic immune cells (i.e., CD8+ T cells, and M1 macrophages), meanwhile decreasing pro-tumor immune cells (i.e., CD3+ T cells, Treg cells, and M2 macrophages). Anti-inflammatory cytokines, including IL1β, IL2, IFNγ, TNF-α, IL4 and IL10 were upregulated by BAK. PD-L1 expression in the tumor was also lowered by BAK. AKT and STAT3 signaling were inhibited by BAK. BAK is an efficient agent in reducing LLC tumor growth. These data support the potential of BAK as a new drug for treating lung cancer by serving as a PD-L1 inhibitor that suppresses the activation of AKT and STAT3.

Sucrose-induced hyperglycemia dysregulates intestinal zinc metabolism and integrity: risk factors for chronic diseases

Objective

Zinc is an essential micronutrient that is critical for many physiological processes, including glucose metabolism, regulation of inflammation, and intestinal barrier function. Further, zinc dysregulation is associated with an increased risk of chronic inflammatory diseases such as type II diabetes, obesity, and inflammatory bowel disease. However, whether altered zinc status is a symptom or cause of disease onset remains unclear. Common symptoms of these three chronic diseases include the onset of increased intestinal permeability and zinc dyshomeostasis. The specific focus of this work is to investigate how dietary sources of intestinal permeability, such as high sucrose consumption, impact transporter-mediated zinc homeostasis and subsequent zinc-dependent physiology contributing to disease development.

Method

We used in vivo subchronic sucrose treatment, ex vivo intestinal organoid culture, and in vitro cell systems. We analyze the alterations in zinc metabolism and intestinal permeability and metabolic outcomes.

Results

We found that subchronic sucrose treatment resulted in systemic changes in steady-state zinc distribution and increased 65Zn transport (blood-to-intestine) along with greater ZIP14 expression at the basolateral membrane of the intestine. Further, sucrose treatment enhanced cell survival of intestinal epithelial cells, activation of the EGFR-AKT-STAT3 pathway, and intestinal permeability.

Conclusion

Our work suggests that subchronic high sucrose consumption alters systemic and intestinal zinc homeostasis linking diet-induced changes in zinc homeostasis to the intestinal permeability and onset of precursors for chronic disease.

Regulation of post-translational modification of PD-L1 and advances in tumor immunotherapy

The immune checkpoint molecules programmed cell death receptor 1 (PD-1) and programmed death ligand 1 (PD-L1) are one of the most promising targets for tumor immunotherapy. PD-L1 is overexpressed on the surface of tumor cells and inhibits T cell activation upon binding to PD⁃1 on the surface of T cells, resulting in tumor immune escape. The therapeutic strategy of targeting PD-1/PD-L1 involves blocking this binding and restoring the tumor-killing effect of immune cells. However, in clinical settings, a relatively low proportion of cancer patients have responded well to PD-1/PD-L1 blockade, and clinical outcomes have reached a bottleneck and no substantial progress has been made. In recent years, PD-L1 post-translation modifications (PTMs) have gradually become a hot topic in the field of PD-L1 research, which will provide new insights to improve the efficacy of current anti-PD-1/PD-L1 therapies. Here, we summarized and discussed multiple PTMs of PD-L1, including glycosylation, ubiquitination, phosphorylation, acetylation and palmitoylation, with a major emphasis on mechanism-based therapeutic strategies (including relevant enzymes and targets that are already in clinical use and that may become drugs in the future). We also summarized the latest research progress of PTMs of PD-L1/PD-1 in regulating immunotherapy. The review provided novel strategies and directions for tumor immunotherapy research based on the PTMs of PD-L1/PD-1.

Combination Curcuma longa and Phyllanthus niruri Extract Potentiate Antiproliferative in Triple Negative Breast Cancer MDAMB-231 Cells

BACKGROUND

Triple negative breast cancer cells (TNBC) are a small part of cancer-inducing cells in breast cancer, which are characterized by high metastatic and self-renewal. Self-renewal has the ability to renew itself and loses control of proliferation. Curcuma longa extract (CL) and Phyllanthus niruri extract (PN) known to have anti-proliferative effects on cancer cells. However, the effects of combination CL and PN on TNBC proliferation still unclear.

AIMS

This study aimed to evaluate the antiproliferative effects of the combination CL and PN on TNBC MDAMB-231 and attempted to elucidate the underlying molecular mechanisms.

SUBJECTS AND METHODS

The dried rhizomes of Curcuma longa and the herbs of Phyllanthus niruri were macerated with ethanol for 72 h.The antiproliferative and synergistic effects of combination CL and PN were investigated using 3-[4,5-dimethylthiazol-2-yl]-2,5 diphenyl tetrazolium bromide (MTT) assay. Combination index values were calculated using CompuSyn (ComboSyn, Inc, Paramus, NJ). The cell cycle and apoptosis assay were determined by propidium iodide (PI) and PI-AnnexinV assay under flow cytometer, respectively. The intracellular ROS levels were evaluated using 2',7'-Dichlorodihydrofluorescein diacetate (DCFDA) assay. The mRNA expressions of proliferation-related genes in the cells were determined using bioinformatic assay.

RESULTS

The CL and PN single treatment caused a potent and dose-dependent decrease in the percentage of viable cells with IC50 value of 13 μg/mL and 45 μg/mL for 24 h, respectively. The combination index values of the different combinations ranged from 0.08 - 0.90, indicating slightly strong to very strong synergistic effects. The combination of CL and PN also remarkably induced the S- and G2/M-phases cell cycle arrest that leading to apoptosis induction. Furthermore, the combination of CL and PN treatment induced the intracellular reactive oxygen species (ROS) levels. Mechanistically, the AKT1, EP300, STAT3 and EGFR signaling as potential targets of combination CL and PN in antiproliferation and antimetastatic of TNBC.

CONCLUSIONS

The combination of CL and PN exerted promising antiproliferative effects in TNBC. Therefore, CL and PN may be considered a potential source for the development of potent anticancer drugs for breast cancer treatment.

Effect of BIM expression on the prognostic value of PD-L1 in advanced non-small cell lung cancer patients treated with EGFR-TKIs

The role of Programmed Cell Death Ligand 1 (PD-L1) expression in predicting epidermal growth factor receptor tyrosine kinase inhibitor (EGFR-TKIs) efficacy remains controversial. Recent studies have highlighted that tumor-intrinsic PD-L1 signaling can be modulated by STAT3, AKT, MET oncogenic pathway, epithelial-mesenchymal transition, or BIM expression. This study aimed to investigate whether these underlying mechanisms affect the prognostic role of PD-L1. We retrospectively enrolled patients with EGFR mutant advanced stage NSCLC who received first-line EGFR-TKI between January 2017 and June 2019, the treatment efficacy of EGFR-TKI was assessed. Kaplan-Meier analysis of progression-free survival (PFS) revealed that patients with high BIM expression had shorter PFS, regardless of PD-L1 expression. This result was also supported by the COX proportional hazard regression analysis. In vitro, we further proved that the knockdown of BIM, instead of PDL1, induced more cell apoptosis following gefitinib treatment. Our data suggest that among the pathways affecting tumor-intrinsic PD-L1 signaling, BIM is potentially the underlying mechanism that affects the role of PD-L1 expression in predicting response to EGFR TKI and mediates cell apoptosis under treatment with gefitinib in EGFR-mutant NSCLC. Further prospective studies are required to validate these results.

Changes of tumor microenvironment in non-small cell lung cancer after TKI treatments

Non-small cell lung cancer (NSCLC) is the most common lung cancer diagnosis, among which epidermal growth factor receptor (EGFR), Kirsten rat sarcoma (KRAS), and anaplastic lymphoma kinase (ALK) mutations are the common genetic drivers. Their relative tyrosine kinase inhibitors (TKIs) have shown a better response for oncogene-driven NSCLC than chemotherapy. However, the development of resistance is inevitable following the treatments, which need a new strategy urgently. Although immunotherapy, a hot topic for cancer therapy, has shown an excellent response for other cancers, few responses for oncogene-driven NSCLC have been presented from the existing evidence, including clinical studies. Recently, the tumor microenvironment (TME) is increasingly thought to be a key parameter for the efficacy of cancer treatment such as targeted therapy or immunotherapy, while evidence has also shown that the TME could be affected by multi-factors, such as TKIs. Here, we discuss changes in the TME in NSCLC after TKI treatments, especially for EGFR-TKIs, to offer information for a new therapy of oncogene-driven NSCLC.

The complex network of transcription factors, immune checkpoint inhibitors and stemness features in colorectal cancer: A recent update

Cancer immunity is regulated by several mechanisms that include co-stimulatory and/or co-inhibitory molecules known as immune checkpoints expressed by the immune cells. In colorectal cancer (CRC), CTLA-4, LAG3, TIM-3 and PD-1 are the major co-inhibitory checkpoints involved in tumor development and progression. On the other hand, the deregulation of transcription factors and cancer stem cells activity plays a major role in the development of drug resistance and in the spread of metastatic disease in CRC. In this review, we describe how the modulation of such transcription factors affects the response of CRC to therapies. We also focus on the role of cancer stem cells in tumor metastasis and chemoresistance and discuss both preclinical and clinical approaches for targeting stem cells to prevent their tumorigenic effect. Finally, we provide an update on the clinical applications of immune checkpoint inhibitors in CRC and discuss the regulatory effects of transcription factors on the expression of the immune inhibitory checkpoints with specific focus on the PD-1 and PD-L1 molecules.

MMP11 is associated with the immune response and immune microenvironment in EGFR-mutant lung adenocarcinoma

Background

High expression of matrix metalloproteinase-11 (MMP11) is associated with various tumors and immune microenvironments. Conversely, poor response to immunotherapy in epidermal growth factor receptor (EGFR)-mutant lung adenocarcinoma (LUAD) patients is closely related to the characteristics of immune microenvironment.

Methods

The Cancer Genome Atlas (TCGA)-LUAD database and our gathered clinical LUAD samples were used to examine the relationship between MMP11 expression and EGFR mutation. Then the correlation between MMP11 and immune response and the difference of immune cell infiltration in different groups were analyzed. Compared the differences in the immune microenvironment between the MMP11-positive and MMP11-negative expression groups using immunohistochemistry (IHC) and multiplex immunohistochemistry.

Results

The expression of MMP11 in samples with exon 19 deletions, exon 21 L858R or de novo exon 20 T790M mutations was higher than wild type, but there was no difference between the samples with uncommon mutation and the wild-type. The high MMP11 expression group had a higher Tumor Immune Dysfunction and Exclusion (TIDE) score. Pathways associated with enrichment in the extracellular matrix (ECM) were the main biological functions of differential genes between the high and low MMP11 groups. The IHC score of MMP11 in the EGFR-mutant group was higher than in the EGFR-wild group. In TCGA-LUAD, the high MMP11 group had a lower proportion of T cell CD8+ and NK cells activated. In the clinical samples, the infiltration levels of T cell CD8+ and NK cells in the tumor parenchyma of EGFR-mutant LUAD was lower in the MMP11-positive than in the MMP11-negative group. The expression levels of tumor cell PD-L1 were higher in the MMP11-positive expression group than in the MMP11-negative expression group, and the proportion of PD1+CD8+ T cells infiltrated was reduced in the MMP11-positive group compared to the MMP11-negative group.

Conclusions

High expression of MMP11 was associated with EGFR mutations. Patients with EGFR-mutant LUAD with high expression of MMP11 responded poorly to immunotherapy, and the percentage of T cell CD8+ and NK cells in immune cell infiltration was lower in MMP11. Consequently, MMP11 is related to the immunological microenvironment of EGFR-mutant lung adenocarcinoma, which may be a predictor of possible immunotherapeutic response.

Combining STAT3-Targeting Agents with Immune Checkpoint Inhibitors in NSCLC

Despite recent therapeutic advances, non-small cell lung cancer (NSCLC) remains the leading cause of cancer-related death. Signal transducer and activator of transcription 3 (STAT3) is a transcription factor (TF) with multiple tumor-promoting effects in NSCLC, including proliferation, anti-apoptosis, angiogenesis, invasion, metastasis, immunosuppression, and drug resistance. Recent studies suggest that STAT3 activation contributes to resistance to immune checkpoint inhibitors. Thus, STAT3 represents an attractive target whose pharmacological modulation in NSCLC may assist in enhancing the efficacy of or overcoming resistance to immune checkpoint inhibitors. In this review, we discuss the biological mechanisms through which STAT3 inhibition synergizes with or overcomes resistance to immune checkpoint inhibitors and highlight the therapeutic strategy of using drugs that target STAT3 as potential combination partners for immune checkpoint inhibitors in the management of NSCLC patients.

Exosome-transmitted S100A4 induces immunosuppression and non-small cell lung cancer development by activating STAT3

Non-small cell lung cancer (NSCLC) is the primary reason of tumor morbidity and mortality worldwide. We aimed to study the transfer process of S100A4 between cells and whether it affected NSCLC development by affecting STAT3 expression. First, S100A4 expression in NSCLC cells was measured. The exosomes in MRC-5, A549, and H1299 cells were isolated and identified. We constructed si-S100A4 and si-PD-L1 to transfect A549 cells and oe-S100A4 to transfect H1299 cells, and tested the transfection efficiency. Cell function experiments were performed to assess cell proliferation, clone number, apoptosis, cell cycle, migration, and invasion abilities. In addition, ChIP was applied to determine the targeting relationship between S100A4 and STAT3. Next, we explored NSCLC cell-derived exosomes role in NSCLC progress by transmitting S100A4. Finally, we verified the function of exosome-transmitted S100A4 in NSCLC in vivo. High expression of S100A4 was secreted by exosomes. After knocking down S100A4, cell proliferation ability was decreased, clones number was decreased, apoptosis was increased, G1 phase was increased, S phase was repressed, and migration and invasion abilities were also decreased. ChIP validated STAT3 and PD-L1 interaction. After knocking down S100A4, PD-L1 expression was decreased, while ov-STAT3 reversed the effect of S100A4 on PD-L1 expression. Meanwhile, S100A4 inhibited T-cell immune activity by activating STAT3. In addition, knockdown of PD-L1 inhibited cell proliferation, migration, and invasion. NSCLC cell-derived exosomes promoted cancer progression by transmitting S100A4 to activate STAT3 pathway. Finally, in vivo experiments further verified that exosome-transmitted S100A4 promoted NSCLC progression. Exosome-transmitted S100A4 induces immunosuppression and the development of NSCLC by activating STAT3.

Matrix protein Tenascin-C promotes kidney fibrosis via STAT3 activation in response to tubular injury

Accumulating evidence indicates that the extracellular matrix (ECM) is not only a consequence of fibrosis, but also contributes to the progression of fibrosis, by creating a profibrotic microenvironment. Tenascin-C (TNC) is an ECM glycoprotein that contains multiple functional domains. We showed that following kidney injury, TNC was markedly induced in fibrotic areas in the kidney from both mouse models and humans with kidney diseases. Genetically deletion of TNC in mice significantly attenuated unilateral ureteral obstruction-induced kidney fibrosis. Further studies showed that TNC promoted the proliferation of kidney interstitial cells via STAT3 activation. TNC-expressing cells in fibrotic kidney were activated fibroblast 2 (Act.Fib2) subpopulation, according to a previously generated single nucleus RNA-seq dataset profiling kidney of mouse UUO model at day 14. To identify and characterize TNC-expressing cells, we generated a TNC-promoter-driven CreER2-IRES-eGFP knock-in mouse line and found that the TNC reporter eGFP was markedly induced in cells around injured tubules that had lost epithelial markers, suggesting TNC was induced in response to epithelium injury. Most of the eGFP-positive cells were both NG2 and PDGFRβ positive. These cells did not carry markers of progenitor cells or macrophages. In conclusion, this study provides strong evidence that matrix protein TNC contributes to kidney fibrosis. TNC pathway may serve as a potential therapeutic target for interstitial fibrosis and the progression of chronic kidney disease.

Radiation-induced PD-L1 expression in tumor and its microenvironment facilitates cancer-immune escape: a narrative review

Background and Objective

Radiotherapy (RT) is one of the fundamental anti-cancer regimens by means of inducing in situ tumor vaccination and driving a systemic anti-tumor immune response. It can affect the tumor microenvironment (TME) components consisting of blood vessels, immunocytes, fibroblasts, and extracellular matrix (ECM), and might subsequently suppress anti-tumor immunity through expression of molecules such as programmed death ligand-1 (PD-L1). Immune checkpoint inhibitors (ICIs), especially anti-programmed cell death 1 (PD-1)/PD-L1 therapies, have been regarded as effective in the reinvigoration of the immune system and another major cancer treatment. Experimentally, combination of RT and ICIs therapy shows a greater synergistic effect than either therapy alone.

Methods

We performed a narrative review of the literature in the PubMed database. The research string comprised various combinations of "radiotherapy", "programmed death-ligand 1", "microenvironment", "exosome", "myeloid cell", "tumor cell", "tumor immunity". The database was searched independently by two authors. A third reviewer mediated any discordance of the results of the two screeners.

Key Content and Findings

RT upregulates PD-L1 expression in tumor cells, tumor-derived exosomes (TEXs), myeloid-derived suppressor cells (MDSCs), and macrophages. The signaling pathways correlated to PD-L1 expression in tumor cells include the DNA damage signaling pathway, epidermal growth factor receptor (EGFR) pathway, interferon gamma (IFN-γ) pathway, cGAS-STING pathway, and JAK/STATs pathway.

Conclusions

PD-L1 upregulation post-RT is found not only in tumor cells but also in the TME and is one of the mechanisms of tumor evasion. Therefore, further studies are necessary to fully comprehend this biological process. Meanwhile, combination of therapies has been shown to be effective, and novel approaches are to be developed as adjuvant to RT and ICIs therapy.

Direct knockdown of phospho-PTM targets mediated by TRIM21 can improve personalized treatment in breast cancer

PURPOSE

In this work for the first time, we showed specific and direct knockdown of important oncogenic proteins of interest and their phospho-PTM targets in tripartite motif containing-21 (TRIM21) overexpressing breast cancer (BC) cells. We revealed the functional and therapeutic consequences of this protein knockdown approach called 'TRIM-ing'.

METHODS

To target HER2, HER3, STAT3 or their activated forms, electroporation and puls-in transfection were standardized for mAb delivery in AU565 and MCF7 BC cell lines. Cancer cells were treated with HER2-targeted medicines (Trastuzumab and Neratinib) or STAT3 targeted inhibitors (Stattic and Niclosamide) with or without respective target TRIM-ing. Real-time PCR, immunoblotting, immunofluorescence, cytotoxicity, short- and long-term cell survival assessments were done following standard methodologies. 3-D structure modelling was used to verify the binding of mAb onto the STAT3 target.

RESULTS

TRIM-ing of HER2 or HER3 receptors or their activated phospho-forms in BC cells showed rapid degradation of respective protein forms, shattering down the downstream signaling (p-ERK, p-AKT) that lasts for up to 7-8 days. This significantly inhibited BC survival (p < 0.001), showing a synergistic therapeutic effect with HER2 medicine trastuzumab or neratinib. Additionally, specific TRIM-ing ability of canonical pY705 or non-canonical pS727 PTMs of STAT3 protein was demonstrated in MCF7 cells, causing significant cytotoxicity (p < 0.05). TRIM-ing of STAT3 PTM, when combined with the same PTM-specific inhibitors, a synergistic treatment effect was observed.

CONCLUSION

The work demonstrated that TRIM-ing could directly reduce various oncogenic targets or their specific activated form inside the cancer cells without compensatory pathway activation, a conundrum limiting the therapeutic benefit of current personalized medicines.

Primary and Acquired Resistance against Immune Check Inhibitors in Non-Small Cell Lung Cancer

Simple Summary

NSCLC accounts for approximately 84% of lung malignancies and the clinical application of ICIs provides a novel and promising strategy. However, approximately 80% of NSCLC patients do not benefit from ICIs due to drug resistance complicated by disciplines and diverse mechanisms. Through this review, we provide a whole map of current understanding of primary and acquired resistance mechanisms in NSCLC. In the first part, resistance mechanisms of 6 FDA-approved ICIs-related primary resistance are collected and arranged into 7 steps of the well-known cancer-immunity cycle. Acquired resistance induced by ICIs are summarized in the second part. In the third part, we discuss the future direction, including the deeper understanding of tumor microenvironment and the combinational treatment. Through this review, clinicians can get clear and direct clues to find the underlying mechanisms in patients and translational researchers can acquire several directions to overcome resistance and apply new combinational treatment.

Abstract

Immune checkpoint inhibitors have emerged as the treatment landscape of advanced non-small cell lung cancer (NSCLC) in recent years. However, approximately 80% of NSCLC patients do not benefit from ICIs due to primary resistance (no initial response) or acquired resistance (tumor relapse after an initial response). In this review, we highlight the mechanisms of primary and secondary resistance. Furthermore, we provide a future direction of the potential predictive biomarkers and the tumor microenvironmental landscape and suggest treatment strategies to overcome these mechanisms.

Platelet‑to‑lymphocyte and neutrophil‑to‑lymphocyte ratios are associated with the efficacy of immunotherapy in stage III/IV non‑small cell lung cancer

Peripheral serological indicators are novel markers associated with prognosis in multiple malignant tumors. In the present study, platelet-to-lymphocyte ratio (PLR) and neutrophil-to-lymphocyte ratio (NLR) were selected to construct a model that predicts long-term survival of patients with stage IIIB-IV non-small cell lung cancer (NSCLC) who received treatment with an anti-programmed cell death protein-1 (PD-1) monoclonal antibody. A total of 133 patients were eligible for the present retrospective study (January 2019-February 2021). The area under the receiver operating characteristic curve was used to compare the diagnostic value of PLR and NLR, and combined PLR and NLR. The objective response rate and disease control rate of each group were obtained and the differences were compared using the χ² test. The prognostic value of these indicators was assessed using the Kaplan-Meier method. Cox regression analysis was used to evaluate risk factors associated with long-term survival. Statistically significant parameters were included in the nomogram. Based on the median PLR and NLR values, the patients were divided into high PLR (H-PLR) (PLR >200.00, 67 patients) and low PLR (L-PLR) (PLR ≤200.00, 66 patients), and high NLR (H-NLR) (NLR >3.56, 65 patients) and low NLR (L-NLR) (NLR ≤3.56, 68 patients) groups. Immune-related adverse events (irAEs) occurred in 22 patients (16.5%) during the observation period, including 18 grade 2–3 irAEs and 4 grade 4 cases. H-NLR and H-PLR were associated with poor progression-free (PFS) and overall survival (OS) in the present study. NLR was an independent prognostic factor for PFS [hazard ratio (HR): 0.201, 95% confidence interval (CI): 0.060-0.670; P=0.009) and OS (HR: 0.413, 95% CI: 0.226-0.754; P=0.004) in this patient group. Therefore, NLR may be used in the prognostication of patients with stage IIIB-IV NSCLC treated with PD-1 inhibitors. These serological markers may be used in combination with established immunomarkers to help predict outcomes.

TSLP protects against sepsis-induced liver injury by inducing autophagy via activation of the PI3K/Akt/STAT3 pathway

BACKGROUND

Liver injury is the main factor in multiple organ failure caused by sepsis. Thymic stromal lymphopoietin (TSLP) is derived from epithelial cells and plays an important role in inflammation, allergies and cancer. The role of TSLP in sepsis-induced liver injury (SILI) is unclear. The purpose of this study was to investigate the effect of TSLP on sepsis-induced liver injury and to clarify the mechanism.

METHODS

Wild-type (WT) mice and TSLPR knockout (TSLPR^-/-) mice were subjected to cecal ligation and puncture (CLP) to generate a SILI model. Liver injury was assessed by measuring the levels of serum alanine aminotransferase (ALT), aspartate aminotransferase (AST), histologic liver injury scores, hepatocyte death, and liver inflammatory factors. Signal pathways were explored in vivo to identify possible mechanisms for TSLP in SILI.

RESULTS

The expression of TSLP and TSLPR increased during SILI. Deletion of TSLPR exacerbated liver injury in terms of serum ALT, AST, histologic liver injury scores, and liver inflammatory factors. Compared with controls, administration of exogenous recombinant mouse TSLP reduced liver injury in WT mice during SILI, but failed to reduce liver injury in TSLPR^-/- mice. TSLP induced autophagy in hepatocytes during SILI. Mechanistically, Akt and STAT3 were activated in WT mice during SILI. The opposite results were observed in TSLPR^-/- mice. In addition, the protective effects of TSLP in WT mice were blocked by PI3K inhibitor, LY294002, during SILI.

CONCLUSION

These results suggest that TSLP can improve liver injury caused by sepsis and its specific mechanism may be related to inducing autophagy through the PI3K/Akt/STAT3 signaling pathway.

Research progress in immunotherapy of NSCLC with EGFR sensitive mutations

Lung cancer is a malignant tumor with high incidence and mortality across the world. The use of immune checkpoint inhibitors for lung cancer has improved the prognosis of some lung cancer patients to a greater extent and provided a new direction for the clinical treatment of lung cancer. Immunotherapy still has limitations in terms of its appropriate population and adverse reactions. Particularly for non-small cell lung cancer (NSCLC) patients with epidermal growth factor receptor (EGFR) mutation, there has been no major breakthrough in current immunotherapy. Whether immunotherapy can bring new benefits after drug resistance is induced by tyrosine kinase inhibitor-targeted therapy and whether the combination of immunotherapy with other treatments can improve the prognosis remain to be studied in depth. In this article, we provide a detailed review of the relevant characteristics of the tumor microenvironment of NSCLC with EGFR mutation and the current research on immunotherapy for NSCLC with EGFR mutation.

Immunotherapy-based combination strategies for treatment of EGFR-TKI-resistant NSCLC

The rapid development of molecular targeted therapy brings hope to patients with advanced non-small-cell lung cancer (NSCLC). However, drug resistance inevitably occurs during treatment with EGFR-tyrosine kinase inhibitors (TKIs). Osimertinib, a third-generation EGFR-TKI, shows a favorable prognosis in T790M-positive NSCLC. Unfortunately, acquired resistance is still a challenge for both patients and clinicians. There is still no consensus on the optimal treatment. PD-1 and its ligand receptor 1 (PD-L1) inhibitors have yielded great progress, especially in patients with no actionable mutations. In this review, the authors take stock of the relationship between EGFR mutations and PD-L1 expression and summarize the important clinical studies on immunotherapy-inhibitor-based treatment in patients with EGFR-TKI-resistant NSCLC.

PD-L1 Expression Correlated with Clinicopathological Factors and Akt/Stat3 Pathway in Oral SCC

Programmed cell death ligand 1 (PD-L1) is an immune checkpoint molecule that inhibits immune responses. The physiological and prognostic role of the PD-L1 signaling pathway in the oral maxillofacial region is unclear. This study aimed to investigate the role of PD-L1 in the progression of oral squamous cell carcinoma (OSCC). Furthermore, clinicopathological factors related to PD-L1 expression were examined in patients with OSCC through immunohistochemistry (IHC) of tissue sections and through an in vitro study in OSCC cells. The medical records, radiographic findings, and mortality referrals of 81 patients obtained from the National Statistical Office were reviewed. IHC was performed on tissue specimens of these patients to determine the expression levels of PD-L1, which showed significant statistical differences based on age, tumor size, TNM stage, cervical lymph node metastasis, and locoregional recurrence. Patients with a high PD-L1 expression had significantly poorer survival rates. Multivariate analysis using the Cox proportional model confirmed the high relative risk ratio for high PD-L1 expression, TNM stage, and neck node metastasis, all of which were significantly associated with a poor prognosis in patients with OSCC. The in vitro study showed that SAS and YD38 cells transfected with PD-L1 siRNA had significantly increased apoptosis, reduced proliferative capacity, and tumorigenicity.

The MicroRNA-106a/20b Strongly Enhances the Antitumour Immune Responses of Dendritic Cells Pulsed with Glioma Stem Cells by Targeting STAT3

BACKGROUND

Evaluate the effect of the miRNA-106a/20b on the efficacy of DCs pulsed with GSCs in activating GSC-specific T cell responses.

METHODS

We cultured GSCs and prepared GSC antigen lysates by apoptosis. Then, immature DCs were pulsed with GSC antigen lysates in vitro. STAT3 levels in DCs were assessed by Western blotting, and the expression of CD80, CD86, and MHC-II was tested by fluorescence-activated cell sorting. The production and secretion of the cytokines IL-6, IL-12, TNF-α, and IL-10 in DCs induced by GSCs were determined by enzyme-linked immunosorbent assay. Finally, the cytotoxic functions of T cells stimulated by GSC-DC fusion cells transfected with a miR-106a/20b mimic in vitro and the antitumour activity in vivo were detected.

RESULTS

We found that the levels of miR-106a/20b were downregulated, but the expression of STAT3 was significantly upregulated. Simultaneously, the inhibition of STAT3 in the fusion cells by STAT3-specific siRNA caused significant upregulation of the expression of CD80, CD86, and MHC-II, and the secretion of the cytokines IL-6 and IL-12 was substantially increased, IL-10 was markedly decreased. These findings revealed that STAT3 is an important regulator of DC maturation. Furthermore, the interactional binding sites between the 3'-untranslated region (3'-UTR) of STAT3 mRNA and miR-106a/20b were predicted by bioinformatics and verified by a dual-luciferase assay. Moreover, the reduction in STAT3 levels in GSC-DCs enhanced the generation of CD8+ T cells and reduced the generation of Foxp3+ regulatory T cells. Meanwhile, the secretion of the T cell cytokine IFN-γ was significantly increased. Further research showed that DCs after miR-106a/20b-mimics transfection could promote the inhibition of GSC proliferation by T cells in vitro and suppress tumour growth in vivo.

CONCLUSIONS

This study indicted that the miR-106a/20b activation could be one of the important molecular mechanisms leading to enhance antitumour immune responses of GSC-mediated DCs, which downregulated the expression of STAT3 to alleviate its the inhibitory effect.

Multicellular Effects of STAT3 in Non-small Cell Lung Cancer: Mechanistic Insights and Therapeutic Opportunities

Non-small cell lung cancer (NSCLC) is the most common type of lung cancer and accounts for 85% of lung cancer cases. Aberrant activation of the Signal Transducer and Activator of Transcription 3 (STAT3) is frequently observed in NSCLC and is associated with a poor prognosis. Pre-clinical studies have revealed an unequivocal role for tumor cell-intrinsic and extrinsic STAT3 signaling in NSCLC by promoting angiogenesis, cell survival, cancer cell stemness, drug resistance, and evasion of anti-tumor immunity. Several STAT3-targeting strategies have also been investigated in pre-clinical models, and include preventing upstream receptor/ligand interactions, promoting the degradation of STAT3 mRNA, and interfering with STAT3 DNA binding. In this review, we discuss the molecular and immunological mechanisms by which persistent STAT3 activation promotes NSCLC development, and the utility of STAT3 as a prognostic and predictive biomarker in NSCLC. We also provide a comprehensive update of STAT3-targeting therapies that are currently undergoing clinical evaluation, and discuss the challenges associated with these treatment modalities in human patients.

PD0325901, an ERK inhibitor, enhances the efficacy of PD-1 inhibitor in non-small cell lung carcinoma

ERK pathway regulated the programmed death ligand-1 (PD-L1) expression which was linked to the response of programmed death-1 (PD-1)/PD-L1 blockade therapy. So it is deducible that ERK inhibitor could enhance the efficacy of PD-1 inhibitor in cancer immunotherapy. In this study, PD0325901, an oral potent ERK inhibitor, strongly enhanced the efficacy of PD-1 antibody in vitro and in vivo models in non-small cell lung carcinoma (NSCLC) cells. Mechanistically, PD0325901 or shRNA-ERK1/2 significantly downregulated the PD-L1 expression in NSCLC cells and increased the CD3⁺ T cells infiltration and functions in tumor tissue. There was a positive correlation between the p-ERK1/2 expression and PD-L1 expression in patients with NSCLC. And the patients with low p-ERK1/2 expression were observed a high response rate of PD-1/PD-L1 blockage therapy. Our results demonstrate that PD0325901, an ERK inhibitor, can enhance the efficacy of PD-1 blockage against NSCLC in vitro and in vivo models. And the combination of ERK inhibitor such as PD0325901 and PD-1/PD-L1 blockage is a promising regimen and encouraged to be further confirmed in the treatment of patients with NSCLC.

The Role of Oncogenes and Redox Signaling in the Regulation of PD-L1 in Cancer

Tumor cells can evade the immune system via multiple mechanisms, including the dysregulation of the immune checkpoint signaling. These signaling molecules are important factors that can either stimulate or inhibit tumor immune response. Under normal physiological conditions, the interaction between programmed cell death ligand 1 (PD-L1) and its receptor, programmed cell death 1 (PD-1), negatively regulates T cell function. In cancer cells, high expression of PD-L1 plays a key role in cancer evasion of the immune surveillance and seems to be correlated with clinical response to immunotherapy. As such, it is important to understand various mechanisms by which PD-L1 is regulated. In this review article, we provide an up-to-date review of the different mechanisms that regulate PD-L1 expression in cancer. We will focus on the roles of oncogenic signals (c-Myc, EML4-ALK, K-ras and p53 mutants), growth factor receptors (EGFR and FGFR), and redox signaling in the regulation of PD-L1 expression and discuss their clinical relevance and therapeutic implications. These oncogenic signalings have common and distinct regulatory mechanisms and can also cooperatively control tumor PD-L1 expression. Finally, strategies to target PD-L1 expression in tumor microenvironment including combination therapies will be also discussed.

Dual inhibition of EGFR and IL-6-STAT3 signalling by miR-146b: a potential targeted therapy for epithelial ovarian cancer

Epidermal growth factor receptor (EGFR) signalling and the interleukin-6 (IL-6)/signal transducer and activator of transcription 3 (STAT3) are aberrantly activated in ovarian cancer. However, inhibition of EGFR signalling in ovarian cancer patients resulted in a disappointing clinical benefit. In this study, we found that EGFR could activate IL-6-STAT3 pathway in ovarian cancer cells. However, we also demonstrated that EGFR knockdown could increase STAT3 phosphorylation in HO8910 and OVCAR-3 ovarian cancer cells. Interestingly, we further demonstrated that the non-coding RNA miR-146b could simultaneously block both the EGFR and IL-6-STAT3 pathways. Finally, our data demonstrated that miR-146b overexpression resulted in a greater suppression of cell migration than STAT3 pathway inhibition alone.These results suggest a complex and heterogeneous role of EGFR in ovarian cancer. Combined blockade of EGFR and IL-6-STAT3 pathways by miR-146b might be a strategy for improving the clinical benefit of targeting the EGFR pathway in ovarian cancer patients in the future.

Liver fibrosis promotes immune escape in hepatocellular carcinoma via GOLM1-mediated PD-L1 upregulation

Immune checkpoint blockade is considered a breakthrough in cancer treatment. However, with the low response rates and therapeutic resistance of patients with hepatocellular carcinoma (HCC), the challenges facing the application of this treatment are tremendous. Liver fibrosis is a key driver of tumor immune escape, the underlying mechanism has never been clarified. This study sought to explore the role of liver fibrosis in regulating tumor-infiltrating lymphocytes (TILs) and inducing tumor immunosuppression. Ninety-nine fixed HCC tissue samples were used to analyze the association between liver fibrosis and immune escape using immunohistochemistry. In HCC patients, low FIB-4 values and high CD8⁺ T cell infiltration were correlated with prolonged survival. Elevated expression of immune checkpoints and attenuated antitumor immunity were observed in CCl₄-induced mice liver fibrosis models and human fibrotic livers compared to control group. GOLM1 levels were increased in livers of patients with fibrosis and mice in response to CCl₄-induced liver fibrosis. CD8⁺ T cell infiltrations were significantly decreased and PD-L1 expression was significantly increased in tumor tissues from hepatocyte-specific GOLM1 transgenic mice (Alb/GOLM1 mice) inducing chemical carcinogenesis compared to their corresponding control WT mice. GOLM1 induced PD-L1 expression via EGFR pathway activation. EGFR inhibitors, especially together with anti-PD-L1 therapy, improved the efficacy of immunotherapy in HCC. These findings illustrate the importance of liver fibrosis-induced immunosuppression as a tumor-promoting mechanism. GOLM1, which is highly upregulated in the fibrotic liver, regulates tumor microenvironmental immune escape via the EGFR/PD-L1 signaling pathway. EGFR blockade may bolster the efficacy of immune checkpoint inhibitors for HCC treatment.

Mechanisms of PD-L1 Regulation in Malignant and Virus-Infected Cells

Programmed cell death protein 1 (PD-1), a receptor on T cells, and its ligand, PD-L1, have been a topic of much interest in cancer research. Both tumour and virus-infected cells can upregulate PD-L1 to suppress cytotoxic T-cell killing. Research on the PD-1/PD-L1 axis has led to the development of anti-PD-1/PD-L1 immune checkpoint blockades (ICBs) as promising cancer therapies. Although effective in some cancer patients, for many, this form of treatment is ineffective due to a lack of immunogenicity in the tumour microenvironment (TME). Despite the development of therapies targeting the PD-1/PD-L1 axis, the mechanisms and pathways through which these proteins are regulated are not completely understood. In this review, we discuss the latest research on molecules of inflammation and innate immunity that regulate PD-L1 expression, how its expression is regulated during viral infection, and how it is modulated by different cancer therapies. We also highlight existing research on the development of different combination therapies with anti-PD-1/PD-L1 antibodies. This information can be used to develop better cancer immunotherapies that take into consideration the pathways involved in the PD-1/PD-L1 axis, so these molecules do not reduce their efficacy, which is currently seen with some cancer therapies. This review will also assist in understanding how the TME changes during treatment, which will provide further rationale for combination therapies.

Discovery of Pyrrole-imidazole Polyamides as PD-L1 Expression Inhibitors and Their Anticancer Activity via Immune and Nonimmune Pathways

In recent years, PD-1 immune checkpoint inhibitors based on monoclonal antibodies have revolutionized cancer therapy, but there still exist unresolved issues, such as the high cost, the relatively low response rates, and so on, compared with small-molecule drugs. Herein a type of pyrrole-imidazole (Py-Im) polyamide as a small-molecule DNA binder was designed and synthesized, which could competitively bind to the same double-stranded DNA stretch in the PD-L1 promoter region as the STAT3 binding site and thus downregulate PD-L1 expression. It was demonstrated that the Py-Im polyamides directly caused apoptosis in tumor cells and retarded cell migration in the absence of T cells through inhibiting the Akt/caspase-3 pathway. Also, in a coculture system, they enhanced the T-cell-mediated killing of tumor cells by the reversal of immune escape. Because such polyamides induced antitumor effects via both immune and nonimmune pathways, they could be further developed as promising PD-L1 gene-targeting antitumor drugs.

ARIH1 signaling promotes anti-tumor immunity by targeting PD-L1 for proteasomal degradation

Cancer expression of PD-L1 suppresses anti-tumor immunity. PD-L1 has emerged as a remarkable therapeutic target. However, the regulation of PD-L1 degradation is not understood. Here, we identify several compounds as inducers of PD-L1 degradation using a high-throughput drug screen. We find EGFR inhibitors promote PD-L1 ubiquitination and proteasomal degradation following GSK3α-mediated phosphorylation of Ser279/Ser283. We identify ARIH1 as the E3 ubiquitin ligase responsible for targeting PD-L1 to degradation. Overexpression of ARIH1 suppresses tumor growth and promotes cytotoxic T cell activation in wild-type, but not in immunocompromised mice, highlighting the role of ARIH1 in anti-tumor immunity. Moreover, combining EGFR inhibitor ES-072 with anti-CTLA4 immunotherapy results in an additive effect on both tumor growth and cytotoxic T cell activation. Our results delineate a mechanism of PD-L1 degradation and cancer escape from immunity via EGFR-GSK3α-ARIH1 signaling and suggest GSK3α and ARIH1 might be potential drug targets to boost anti-tumor immunity and enhance immunotherapies.

Targeting EphA2 suppresses hepatocellular carcinoma initiation and progression by dual inhibition of JAK1/STAT3 and AKT signaling

Hepatocellular carcinoma (HCC) remains one of the deadliest malignancies worldwide. One major obstacle to treatment is a lack of effective molecular-targeted therapies. In this study, we find that EphA2 expression and signaling are enriched in human HCC and associated with poor prognosis. Loss of EphA2 suppresses the initiation and growth of HCC both in vitro and in vivo. Furthermore, CRISPR/CAS9-mediated EphA2 inhibition significantly delays tumor development in a genetically engineered murine model of HCC. Mechanistically, we discover that targeting EphA2 suppresses both AKT and JAK1/STAT3 signaling, two separate oncogenic pathways in HCC. We also identify a small molecule kinase inhibitor of EphA2 that suppresses tumor progression in a murine HCC model. Together, our results suggest EphA2 as a promising therapeutic target for HCC.

The progress and challenge of anti-PD-1/PD-L1 immunotherapy in treating non-small cell lung cancer

The use of programmed cell-death protein 1 (PD-1)/programmed cell-death ligand 1 (PD-L1) inhibitors is the standard therapy for the first-line or second-line treatment of patients with non-small-cell lung cancer (NSCLC). In contrast to current traditional treatments such as chemotherapy or radiotherapy, anti-PD-1 and anti-PD-L1 treatments can directly attenuate tumour-mediated exhaustion and effectively modulate the host anti-tumour immune response in vivo. In addition, compared with traditional therapy, PD-1/PD-L1 inhibitor monotherapy can significantly prolong survival without obvious side effects in the treatment of advanced NSCLC. Ideally, several biomarkers could be used to monitor the safety and effectiveness of anti-PD-1 and anti-PD-L1 treatments; however, the current lack of optimal prognostic markers remains a widespread limitation and challenge for further clinical applications, as does the possibility of immune-related adverse events and drug resistance. In this review, we aimed to summarise the latest progress in anti-PD-1/anti-PD-L1 treatment of advanced NSCLC, worldwide, including in China. An exploration of underlying biomarker identification and future challenges will be discussed in this article to facilitate translational studies in cancer immunotherapy.

Discovery of CAPE derivatives as dual EGFR and CSK inhibitors with anticancer activity in a murine model of hepatocellular carcinoma

Caffeic acid phenethyl ester (CAPE), a bioactive component extracted from propolis of honeybee hives, can inhibit hepatocellular carcinoma (HCC). In order to explore more stable CAPE derivatives, 25 compounds were designed, synthesized, and pharmacologically assessed in vitro and in vivo as anti-tumor agents in HCC. Compounds 8d, 8f, 8l, 8j, and 8k showed favorable antiproliferative activity than other compounds including CAPE in the HCC cell lines. Based on the result of QTRP (Quantitative Thiol Reactivity Profiling), epidermal growth factor receptor (EGFR) and C-terminal Src kinase (CSK) were supposed to the targets of 8f, which was confirmed by binding mode analysis. Furthermore, compounds 8f, 8l, 8j, 8k, 8g, and 8h showed potent inhibitory effects against both CSK and EGFR than other derivatives in an ADP-Glo™ kinase assay. The representative compound, 8f, potently inhibited various tumor growth in murine model including murine hepatocellular carcinoma H22, meanwhile downregulating the EGFR/AKT pathway and enhancing T cell proliferation through inhibition of CSK. Metabolic stability in vitro suggested 8f and 8k were more stable in mouse plasma than CAPE and susceptible to metabolism in liver microsomes. The overall excellent profile of compound 8f makes it a potential candidate for further preclinical investigation.

Transcriptional Regulation of Cancer Immune Checkpoints: Emerging Strategies for Immunotherapy

The study of immune evasion has gained a well-deserved eminence in cancer research by successfully developing a new class of therapeutics, immune checkpoint inhibitors, such as pembrolizumab and nivolumab, anti-PD-1 antibodies. By aiming at the immune checkpoint blockade (ICB), these new therapeutics have advanced cancer treatment with notable increases in overall survival and tumor remission. However, recent reports reveal that 40-60% of patients fail to benefit from ICB therapy due to acquired resistance or tumor relapse. This resistance may stem from increased expression of co-inhibitory immune checkpoints or alterations in the tumor microenvironment that promotes immune suppression. Because these mechanisms are poorly elucidated, the transcription factors that regulate immune checkpoints, known as "master regulators", have garnered interest. These include AP-1, IRF-1, MYC, and STAT3, which are known to regulate PD/PD-L1 and CTLA-4. Identifying these and other potential master regulators as putative therapeutic targets or biomarkers can be facilitated by mining cancer literature, public datasets, and cancer genomics resources. In this review, we describe recent advances in master regulator identification and characterization of the mechanisms underlying immune checkpoints regulation, and discuss how these master regulators of immune checkpoint molecular expression can be targeted as a form of auxiliary therapeutic strategy to complement traditional immunotherapy.

An aberrant STAT pathway is central to COVID-19

COVID-19 is caused by SARS-CoV-2 infection and characterized by diverse clinical symptoms. Type I interferon (IFN-I) production is impaired and severe cases lead to ARDS and widespread coagulopathy. We propose that COVID-19 pathophysiology is initiated by SARS-CoV-2 gene products, the NSP1 and ORF6 proteins, leading to a catastrophic cascade of failures. These viral components induce signal transducer and activator of transcription 1 (STAT1) dysfunction and compensatory hyperactivation of STAT3. In SARS-CoV-2-infected cells, a positive feedback loop established between STAT3 and plasminogen activator inhibitor-1 (PAI-1) may lead to an escalating cycle of activation in common with the interdependent signaling networks affected in COVID-19. Specifically, PAI-1 upregulation leads to coagulopathy characterized by intravascular thrombi. Overproduced PAI-1 binds to TLR4 on macrophages, inducing the secretion of proinflammatory cytokines and chemokines. The recruitment and subsequent activation of innate immune cells within an infected lung drives the destruction of lung architecture, which leads to the infection of regional endothelial cells and produces a hypoxic environment that further stimulates PAI-1 production. Acute lung injury also activates EGFR and leads to the phosphorylation of STAT3. COVID-19 patients' autopsies frequently exhibit diffuse alveolar damage (DAD) and increased hyaluronan (HA) production which also leads to higher levels of PAI-1. COVID-19 risk factors are consistent with this scenario, as PAI-1 levels are increased in hypertension, obesity, diabetes, cardiovascular diseases, and old age. We discuss the possibility of using various approved drugs, or drugs currently in clinical development, to treat COVID-19. This perspective suggests to enhance STAT1 activity and/or inhibit STAT3 functions for COVID-19 treatment. This might derail the escalating STAT3/PAI-1 cycle central to COVID-19.

An aberrant STAT pathway is central to COVID-19

COVID-19 is caused by SARS-CoV-2 infection and characterized by diverse clinical symptoms. Type I interferon (IFN-I) production is impaired and severe cases lead to ARDS and widespread coagulopathy. We propose that COVID-19 pathophysiology is initiated by SARS-CoV-2 gene products, the NSP1 and ORF6 proteins, leading to a catastrophic cascade of failures. These viral components induce signal transducer and activator of transcription 1 (STAT1) dysfunction and compensatory hyperactivation of STAT3. In SARS-CoV-2-infected cells, a positive feedback loop established between STAT3 and plasminogen activator inhibitor-1 (PAI-1) may lead to an escalating cycle of activation in common with the interdependent signaling networks affected in COVID-19. Specifically, PAI-1 upregulation leads to coagulopathy characterized by intravascular thrombi. Overproduced PAI-1 binds to TLR4 on macrophages, inducing the secretion of proinflammatory cytokines and chemokines. The recruitment and subsequent activation of innate immune cells within an infected lung drives the destruction of lung architecture, which leads to the infection of regional endothelial cells and produces a hypoxic environment that further stimulates PAI-1 production. Acute lung injury also activates EGFR and leads to the phosphorylation of STAT3. COVID-19 patients' autopsies frequently exhibit diffuse alveolar damage (DAD) and increased hyaluronan (HA) production which also leads to higher levels of PAI-1. COVID-19 risk factors are consistent with this scenario, as PAI-1 levels are increased in hypertension, obesity, diabetes, cardiovascular diseases, and old age. We discuss the possibility of using various approved drugs, or drugs currently in clinical development, to treat COVID-19. This perspective suggests to enhance STAT1 activity and/or inhibit STAT3 functions for COVID-19 treatment. This might derail the escalating STAT3/PAI-1 cycle central to COVID-19.

CKS1B promotes cell proliferation and invasion by activating STAT3/PD-L1 and phosphorylation of Akt signaling in papillary thyroid carcinoma

Objective

To investigate role of GKS1B and its relationship between STAT3/PD‐L1 and p‐Akt in papillary thyroid carcinoma (PTC).

Methods

Expression of GKS1B and PD‐L1 was determined in PTC cell lines. GKS1B was overexpressed or knocked down by transfection with overexpression plasmids or si‐CKS1B. STAT3 inhibitor WP1066 was used to suppress STAT3, and PD‐L1 inhibitor Pembrolizumab was used to block PD‐L1. Cell viability and invasion were evaluated by MTT and transwell assay, respectively. The expression of STAT3, p‐STAT3, Akt, and p‐Akt was measured using Western blotting.

Results

Both protein levels and mRNA levels of CKS1B and PD‐L1 were remarkably up‐regulated in PTC cell lines. Knockdown of CKS1B significantly inhibited cell viability and invasion of PTC cells and suppressed STAT3/PD‐L1 signaling and Akt phosphorylation, while overexpression of CKS1B led to opposite results. Inhibition of STAT3 or PD‐L1 reversed the effects of overexpressed CKS1B on PTC cells.

Conclusion

The overexpression of CSK1B could promote cell viability and invasion of PTC cells through activation of STAT3/PD‐L1 signaling and Akt phosphorylation.

Protein tyrosine phosphatase receptor type delta (PTPRD) suppresses the expression of PD-L1 in human hepatocellular carcinoma by down-regulating STAT3

BACKGROUND

Protein tyrosine phosphatase receptor type delta (PTPRD) is a tumor suppressor that is often inactivated in hepatocellular carcinoma (HCC). However, the mechanisms of how PTPRD inhibits HCC are not well understood. Programmed cell death ligand 1 (PD-L1), an immune checkpoint, plays a seminal role in the regulation of carcinogenesis of HCC. The sustained activation of STAT3 is closely related to PTPRD deletion and PD-L1 overexpression; however, whether there is a relationship between PTPRD and PD-L1 expression in HCC has not been investigated. This study aims to investigate the relationship between PTPRD and PD-L1 in HCC samples and illuminate potential new molecular mechanisms of PTPRD effects on PD-L1 in HepG2 cells.

METHODS

We collected 16 pairs of tumorous tissues and adjacent normal tissues from HCC patients. The mRNA and protein expression levels of PTPRD and PD-L1 in the HCC tissues were detected by RT-PCR and Western blot analysis. Next, Spearman's correlation analysis was performed to evaluate the relationship between PTPRD and PD-L1. Then, we transfected the overexpressed or knocked-down PTPRD genes into the HepG2 cell line, and the effects of PTPRD on PD-L1 in HCC cells were evaluated. The activity from the STAT3 and p-STAT3 in the HepG2 cells transfected with PTPRD gene overexpression and knockdown was determined by Western blotting tests.

RESULTS

The expression of PTPRD was significantly down-regulated in the HCC tissues compared with the adjacent control tissues; however, PD-L1 was significantly higher in the HCC tissues. There was a negative correlation between PTPRD and PD-L1 expression in the HCC tissues. PTPRD over-expression significantly inhibited PD-L1 expression; meanwhile, PTPRD depletion promoted PD-L1 expression in the HepG2 cells. Furthermore, PTPRD over-expression significantly inhibited the expression of STAT3 and p-STAT3, while PTPRD depletion promoted these cytokines. Our studies revealed that PTPRD repressed PD-L1 expression in the HepG2 cells, which might occur via the STAT3 pathway.

CONCLUSIONS

The results from our study show that PTPRD and PD-L1 are negatively correlated in HCC tissues. PTPRD suppresses PD-L1 expression in HepG2 cells by down-regulating STAT3. These findings are expected to become a new target for the immunotherapy of HCC.

S-allylmercaptocysteine inhibits mucin overexpression and inflammation via MAPKs and PI3K-Akt signaling pathways in acute respiratory distress syndrome

Cytokine storm is an important cause of acute respiratory distress syndrome and multiple organ failure. Excessive secretion and accumulation of mucins on the surface of airway cause airway obstruction and exacerbate lung infections. MUC5AC and MUC5B are the main secreted mucins and overexpressed in various inflammatory responses. S-allylmercaptocysteine, a water-soluble organic sulfur compound extracted from garlic, has anti-inflammatory and anti-oxidative effects for various pulmonary diseases. The aim of this work was to investigate the therapeutic effects of SAMC on mucin overproduction and inflammation in 16HBE cells and LPS-induced ARDS mice. Results show that SAMC treatment ameliorated inflammatory cell infiltration and lung histopathological changes in the LPS-induced ARDS mice. SAMC also inhibited the expressions of MUC5AC and MUC5B, decreased the production of pro-inflammatory markers (IL-6, TNF-α, CD86 and IL-12) and increased the production of anti-inflammatory markers (IL-10, CD206 and TGF-β). These results confirm that SAMC had potential beneficial effects on suppressed hyperinflammation and mucin overexpression. Furthermore, SAMC exerted the therapeutic effects through the inhibition of phosphorylation of MAPKs and PI3K-Akt signaling pathways in the 16HBE cells and mice. Overall, our results demonstrate the effects of SAMC on the LPS-induced mucin overproduction and inflammation both in the 16HBE cells and mice.

Long noncoding RNA PANDAR inhibits the development of lung cancer by regulating autophagy and apoptosis pathways

Background: LncRNAs has been shown to play important roles in the progression of lung cancer, but it remains poorly understood whether lncRNAs affect the occurrence and development of lung cancer by regulating autophagy and apoptosis levels. Here, we investigated the roles of PANDAR in NSCLC. Materials and Methods: The expression profile and clinical application of PANDAR and its possible target gene BECN1 were tested in 276 cases of lung cancer tissues. Through some actual experiments, we explored functions of PANDAR about proliferation, apoptosis and autophagy of NSCLC cells in vitro. Results: PANDAR was found to downregulate both in lung cancer tissues and cell lines compared with corresponding controls (P < 0.05 for all), which was related to tumor stage (P < 0.05). Moreover, autophagy related gene BECN1 was also downregulated in lung cancer tissues comparison with normal tissues (P < 0.01), and there was a significant positive correlation between PANDAR and BECN1 levels (r = 0.789, P < 0.001). So, the high expression of PANDAR increased BECN1 expression levels and impaired the proliferation of NSCLC cell lines in vitro. Furthermore study showed PANDAR could regulate cell autophagy and apoptosis levels. Conclusion: These results indicated lncRNA PANDAR was a tumor suppressor and can inhibit NSCLC cell proliferation by activating autophagy and apoptosis pathways via upregulation of BECN1 expression.

Genetic Alterations and Checkpoint Expression: Mechanisms and Models for Drug Discovery

In this chapter, we will sketch a story that begins with the breakdown of chromosome homeostasis and genomic stability. Genomic alterations may render tumor cells eternal life at the expense of immunogenicity. Although antitumor immunity can be primed through neoantigens or inflammatory signals, tumor cells have evolved countermeasures to evade immune surveillance and strike back by modulating immune checkpoint related pathways. At present, monoclonal antibody drugs targeting checkpoints like PD-1 and CTLA-4 have significantly prolonged the survival of a variety of cancer patients, and thus have marked a great achievement in the history of antitumor therapy. Nevertheless, this is not the end of the story. As the relationship between genomic alteration and checkpoint expression is being delineated though the advances of preclinical animal models and emerging technologies, novel checkpoint targets are on the way to be discovered.

The Inhibitory Mechanisms of Tumor PD-L1 Expression by Natural Bioactive Gallic Acid in Non-Small-Cell Lung Cancer (NSCLC) Cells

Non-small-cell lung cancer (NSCLC) is the most common lung cancer subtype and accounts for more than 80% of all lung cancer cases. Epidermal growth factor receptor (EGFR) phosphorylation by binding growth factors such as EGF activates downstream prooncogenic signaling pathways including KRAS-ERK, JAK-STAT, and PI3K-AKT. These pathways promote the tumor progression of NSCLC by inducing uncontrolled cell cycle, proliferation, migration, and programmed death-ligand 1 (PD-L1) expression. New cytotoxic drugs have facilitated considerable progress in NSCLC treatment, but side effects are still a significant cause of mortality. Gallic acid (3,4,5-trihydroxybenzoic acid; GA) is a phenolic natural compound, isolated from plant derivatives, that has been reported to show anticancer effects. We demonstrated the tumor-suppressive effect of GA, which induced the decrease of PD-L1 expression through binding to EGFR in NSCLC. This binding inhibited the phosphorylation of EGFR, subsequently inducing the inhibition of PI3K and AKT phosphorylation, which triggered the activation of p53. The p53-dependent upregulation of miR-34a induced PD-L1 downregulation. Further, we revealed the combination effect of GA and anti-PD-1 monoclonal antibody in an NSCLC-cell and peripheral blood mononuclear-cell coculture system. We propose a novel therapeutic application of GA for immunotherapy and chemotherapy in NSCLC.