Tumor Cell Signaling Research Articles

Enhancing Therapeutic Efficacy of Oncolytic Herpes Simplex Virus-1 with Integrin β1 Blocking Antibody OS2966.

Integrin β1 receptor, expressed on the surface of tumor cells and macrophages in the tumor microenvironment (TME), has been implicated in both tumor progression and resistance to multiple modalities of therapy. OS2966 is the first clinical-ready humanized monoclonal antibody to block integrin β1 and was recently orphan designated by the FDA Office of Orphan Products Development. Here, we tested therapeutic potential of OS2966-mediated integrin β1 blockade to enhance the efficacy of oncolytic herpes simplex virus-1 (oHSV) through evaluation of virus replication, tumor cell killing efficiency, effect on the antiviral signaling pathway, co-culture assays of oHSV-infected cells with macrophages, and in vivo bioluminescence imaging on mammary fat pad triple-negative breast cancer xenograft and subcutaneous and intracranial glioma xenografts. OS2966 treatment decreased interferon signaling and proinflammatory cytokine induction in oHSV-treated tumor cells and inhibited migration of macrophages, resulting in enhanced oHSV replication and cytotoxicity. OS2966 treatment also significantly enhanced oHSV replication and oHSV-mediated antitumor efficacy in orthotopic xenograft models, including triple-negative breast cancer and glioblastoma. The results demonstrated the synergistic potential of the combinatory treatment approach with OS2966 to improve antitumor efficacy of conventional oHSV therapy.

Inhibition of Hedgehog Signaling in Fibroblasts, Pancreatic, and Lung Tumor Cells by Oxy186, an Oxysterol Analogue with Drug-Like Properties.

The widespread involvement of the Hedgehog (Hh) signaling pathway in human malignancies has motivated the clinical development of Smoothened (Smo) antagonists, such as vismodegib and sonidegib. However, Smo antagonists have failed to benefit patients suffering from Hh pathway-dependent solid tumors, such as pancreatic, colorectal, or ovarian cancer. Hh-dependent cancers are often driven by activating mutations that occur downstream of Smo and directly activate the transcription factors known as glioma-associated oncogenes (Gli1-3). Hence, the direct targeting of Gli could be a more effective strategy for achieving disease modification compared to Smo antagonism. In this study, we report on the biological and pharmacological evaluation of Oxy186, a semisynthetic oxysterol analogue, as a novel inhibitor of Hh signaling acting downstream of Smo, with encouraging drug-like properties. Oxy186 exhibits strong inhibition of ligand-induced Hh signaling in NIH3T3-E1 fibroblasts, as well as in constitutively activated Hh signaling in Suppressor of Fused (Sufu) null mouse embryonic fibroblast (MEF) cells. Oxy186 also inhibits Gli1 transcriptional activity in NIH3T3-E1 cells expressing exogenous Gli1 and Gli-dependent reporter constructs. Furthermore, Oxy186 suppresses Hh signaling in PANC-1 cells, a human pancreatic ductal adenocarcinoma (PDAC) tumor cell line, as well as PANC-1 cell proliferation in vitro, and in human lung cancer cell lines, A549 and H2039.

Absence of PD-L1 expression on tumor cells in the context of an activated immune infiltrate may indicate impaired IFNγ signaling in non-small cell lung cancer.

BackgroundIn non-small cell lung cancer (NSCLC), PD-L1 expression on either tumor cells (TC) or both TC and tumor-infiltrating immune cells (IC) is currently the most used biomarker in cancer immunotherapy. However, the mechanisms involved in PD-L1 regulation are not fully understood. To provide better insight in these mechanisms, a multiangular analysis approach was used to combine protein and mRNA expression with several clinicopathological characteristics.Patients and methodsArchival tissues from 640 early stage, resected NSCLC patients were analyzed with immunohistochemistry for expression of PD-L1 and CD8 infiltration. In addition, mutational status and expression of a selection of immune genes involved in the PD-L1/PD-1 axis and T-cell response was determined.ResultsTumors with high PD-L1 expression on TC or on IC represent two subsets of NSCLC with minimal overlap. We observed that PD-L1 expression on IC irrespective of expression on TC is a good marker for inflammation within tumors. In the tumors with the highest IC expression and absent TC expression an association with reduced IFNγ downstream signaling in tumor cells was observed.ConclusionsThese results show that PD-L1 expression on TC and IC are both independent hallmarks of the inflamed phenotype in NSCLC, and TC-negative/IC-high tumors can also be categorized as inflamed. The lack of correlation between PD-L1 TC and IC expression in this subgroup may be caused by impaired IFNγ signaling in tumor cells. These findings may bring a better understanding of the tumor-immune system interaction and the clinical relevance of PD-L1 expression on IC irrespective of PD-L1 expression on TC.

Major vault protein suppresses lung cancer cell proliferation by inhibiting STAT3 signaling pathway

BackgroundMajor vault protein (MVP) is the major component of vault, a eukaryotic organelle involved in multiple cellular processes, and is important in multiple cellular processes and diseases including the drug resistance in cancer chemotherapies. However, the role of MVP in lung cancer remains unclear.MethodsWe examined MVP expression in 120 non-small cell lung cancer (NSCLC) tumors and matched normal tissues by immunohistochemistry. Its relationship with NSCLC prognosis was determined by investigating the patient cohort and analyzing the data from a published dataset consisting with more than 1900 lung cancer patients. We further performed shRNA-introduced knockdown of MVP in Lewis lung carcinoma (LLC) cells and examined its effects on the tumor formation in a xenograft mouse model and the tumor cell proliferation, apoptosis, and signal transduction in vitro.ResultsWe found that MVP was up-regulated significantly in tumor tissues compared with the matched tumor-adjacent normal tissues. The increased expression of MVP in lung adenocarcinoma was associated with a better prognosis. Knockdown of MVP in LLC cells promoted xenografted lung cancer formation in mice, which was accompanied with accelerated tumor cell proliferation and suppressed cell apoptosis in vitro. Knockdown of MVP stimulated STAT3 phosphorylation, nuclear localization, and activation of JAK2 and RAF/MEK/ERK pathways in LLC cells. Administration of STAT3 inhibitor WP1066 could prevent MVP knockdown induced tumorigenesis.ConclusionsOur findings demonstrate that MVP may act as a lung tumor suppressor via inhibiting STAT3 pathway. MVP would be a potential target for novel therapies of lung adenocarcinoma.

Tumor Microenvironment Regulation by the Endoplasmic Reticulum Stress Transmission Mediator Golgi Protein 73 in Mice.

The unfolded protein response (UPR) signal in tumor cells activates UPR signaling in neighboring macrophages, which leads to tumor-promoting inflammation by up-regulating UPR target genes and proinflammatory cytokines. However, the molecular basis of this endoplasmic reticulum (ER) stress transmission remains largely unclear. Here, we identified the secreted form of Golgi protein 73 (GP73), a Golgi-associated protein functional critical for hepatocellular carcinoma (HCC) growth and metastasis, is indispensable for ER stress transmission. Notably, ER stressors increased the cellular secretion of GP73. Through GRP78, the secreted GP73 stimulated ER stress activation in neighboring macrophages, which then released cytokines and chemokines involved in the tumor-associated macrophage (TAM) phenotype. Analysis of HCC patients revealed a positive correlation of GP73 with glucose-regulated protein 78 (GRP78) expression and TAM density. High GP73 and CD206 expression was associated with poor prognosis. Blockade of GP73 decreased the density of TAMs, inhibited tumor growth, and prolonged survival in two mouse HCC models. Conclusion: Our findings provide insight into the molecular mechanisms of extracellular GP73 in the amplification and transmission of ER stress signals.

The dark side of IL-1: role in prostate cancer progression

Abstract IL-1 is a pro-inflammatory cytokine essential for host defense against pathogens, but its role in cancer progression remains understudied. Recently our lab identified the IL-1 pathway as a molecular mechanism responsible for myeloid-driven prostate cancer development. Here, we report that IL-1 signaling in tumor cells drives prostate cancer progression. To identify the contribution of IL-1 signaling in prostate cancer progression, we downregulated expression of IL1R1 (the only known functional receptor for IL-1α/β) using shRNA or Crisr/Cas9 in androgen-sensitive (LNCaP) and androgen-independent (PC-3M) prostate cancer cell lines. We found that IL-1α inhibited expression of androgen receptor in LNCaP while suppression of IL-1 signaling abrogated this effect. The expression of neuron-specific enolase which was shown to be a prognostic marker associated with poor survival outcome was significantly reduced in PC-3M cells lacking IL1R1. Downregulation of IL-1 signaling in cancer cells resulted in significant inhibition of prostate tumor growth while no effect on cell proliferation was detected. We established this phenomenon and found several possible mechanisms underlying it. We found that knocking down of IL1R1 in cancer cells resulted in suppression of mTOR and ACC signaling in tumors. TUNEL staining revealed increased number of apoptotic cells in shIL1R1-PC-3M tumors. Tumors lacking IL1R1 were characterized by impaired vascularization which was accompanied by reduced COX-2, VEGF-A and IL-8 expression. Taken together, our findings indicate that downregulation of IL-1 signaling modifies prostate cancer cell phenotype and suppresses tumor growth.

MyD88 dimerization inhibitors for targeting Diffuse Large B-cell Lymphomas

Abstract A recurring single amino acid somatic mutation associated with human diffuse large B cell lymphomas (DLBCLs), correlates with tumor cell proliferation and survival involving spontaneous and sustained activation of MyD88-dependent NF-κB and Janus Kinase (JAK) signaling pathways. MyD88 acts as a central signaling adapter for mediating innate and cytokine driven inflammation for the Interleukin-1 (IL-1R) and Toll-like receptors (TLRs). Computer aided molecular modeling of MyD88 and in silico screening have identified and functionally characterized MyD88 specific small molecule compounds shown to protect against Staphylococcal enterotoxin B (SEB) induced death in animal models. We hypothesize that MyD88 specific small molecule compounds may also be useful in treating DLBCLs bearing the oncogenic mutation MYD88L265P. Using in vitro and in vivo studies we evaluate MyD88 specific small molecule compounds for the ability to inhibit tumor cell proliferation and signaling in human patient cancer cells OCI Ly3 bearing the oncogenic mutation MYD88 L265P and OCI Ly19 DLBCLs. Previously we identified differences in the ability of MyD88 small molecule compounds to inhibit cell proliferation in activated human B cell lymphoma cells bearing the MyD88 L265P mutation. We now correlate these differences with a reduction of MyD88 interaction with IRAK in small molecule treated OCI-Ly3 cells bearing the MYD88 L265P mutation in comparison to OCI-Ly19 (wt-MyD88) and treated controls, as measured by CoIP. We continue to characterize MyD88 specific small molecule compounds that target MyD88 dimerization for their ability to reduce MyD88 containing signaling complexes in DLBCLs bearing MYD88 L265P mutation.

Overexpression of LGR-5 as a Predictor of Poor Outcome in Patients with Hepatocellular Carcinoma.

Hepatocarcinogenesis and distant metastasis pose major challenges for physicians. They are regulated by several genes, such as AKT, JUK, Wnt, and P53, and their expression activates several important processes such as cell proliferation, migration, motility, and interaction in the microenvironment. The leucine-rich repeat-containing G-protein-coupled receptor 5 (LGR-5) is a novel biomarker, particularly in stem cells, and is involved in embryogenesis, tumor development, and tumor cell signal transduction. Here, we investigated LGR-5 expression using immunohistochemistry and analyzed the correlation between clinical features and prognosis in patients with hepatocellular carcinoma (HCC). We found that LGR-5 expression was higher in tumor tissues than in normal liver tissues, and that high LGR-5 expression possibly favored poor outcomes in HCC, especially in well/moderate differentiation grade, hepatitis C virus (HCV)-negative, and hepatitis B virus (HBV)-positive groups. Thus, the LGR-5 marker is suggested to be a routine biomarker for poor prognosis, thereby providing a platform for anti-LGR-5-targeted therapy in the future.

Tackling Immunotherapy Resistance: Developing Rational Combinations of Immunotherapy and Targeted Drugs

Abstract Mechanisms of resistance to immunotherapies are multiple and complex with components intrinsic to the tumor cell and within the immune microenvironment. We review evidence of the interaction of tumor cell signaling pathways with immune pathways and the role this plays in de novo and acquired resistance. The mitogen-activated protein kinase (MAPK) pathway activation and effects on T-cell function are discussed. Phosphoinositide 3-kinase (PI3K) pathway activation (including PTEN loss of function) correlates with T-cell inhibition and immunotherapy resistance. Wnt signaling has been implicated in T-cell function suppression. Key evidence from preclinical models exists for the role of these signaling pathways and is described. Clinical evidence is less advanced though correlation of mutations in key nodes with immune resistance provides a limited clinical correlation. Serial biomarker analysis in patients receiving targeted drugs has been attempted with notable examples including BRAF inhibition in melanoma patients resulting in dynamic changes in programmed death-ligand 1 (PD-L1) expression and tumor-infiltrating lymphocytes. Drug combinations aim to overcome mechanisms of resistance, and recent years have seen numerous combinations of targeted therapies and immune checkpoint inhibitors proposed. However, clear biological rationale and thoughtful trial designs with a translational focus are required to allow such combinations to achieve their full potential.

Genomic testing, tumor microenvironment and targeted therapy of Hedgehog-related human cancers.

Hedgehog signals are transduced through Patched receptors to the Smoothened (SMO)-SUFU-GLI and SMO-Gi-RhoA signaling cascades. MTOR-S6K1 and MEK-ERK signals are also transduced to GLI activators through post-translational modifications. The GLI transcription network up-regulates target genes, such as BCL2, FOXA2, FOXE1, FOXF1, FOXL1, FOXM1, GLI1, HHIP, PTCH1 and WNT2B, in a cellular context-dependent manner. Aberrant Hedgehog signaling in tumor cells leads to self-renewal, survival, proliferation and invasion. Paracrine Hedgehog signaling in the tumor microenvironment (TME), which harbors cancer-associated fibroblasts, leads to angiogenesis, fibrosis, immune evasion and neuropathic pain. Hedgehog-related genetic alterations occur frequently in basal cell carcinoma (BCC) (85%) and Sonic Hedgehog (SHH)-subgroup medulloblastoma (87%) and less frequently in breast cancer, colorectal cancer, gastric cancer, pancreatic cancer, non-small-cell lung cancer (NSCLC) and ovarian cancer. Among investigational SMO inhibitors, vismodegib and sonidegib are approved for the treatment of patients with BCC, and glasdegib is approved for the treatment of patients with acute myeloid leukemia (AML). Resistance to SMO inhibitors is caused by acquired SMO mutations, SUFU deletions, GLI2 amplification, other by-passing mechanisms of GLI activation and WNT/β-catenin signaling activation. GLI-DNA-interaction inhibitors (glabrescione B and GANT61), GLI2 destabilizers (arsenic trioxide and pirfenidone) and a GLI-deacetylation inhibitor (4SC-202) were shown to block GLI-dependent transcription and tumorigenesis in preclinical studies. By contrast, SMO inhibitors can remodel the immunosuppressive TME that is dominated by M2-like tumor-associated macrophages (M2-TAMs), myeloid-derived suppressor cells and regulatory T cells, and thus, a Phase I/II clinical trial of the immune checkpoint inhibitor pembrolizumab with or without vismodegib in BCC patients is ongoing.

CuS Nanoparticles as a Photodynamic Nanoswitch for Abrogating Bypass Signaling To Overcome Gefitinib Resistance.

Bypass signaling activation plays a crucial role in the acquired resistance of gefitinib, the first targeted drug in the clinic to treat advanced non-small cell lung cancer. Although the inactivation of bypass signaling by small-molecule inhibitors or monoclonal antibodies may overcome gefitinib resistance, their clinical use has been limited by the complex production process and off-target toxicity. Here we show CuS nanoparticles (NPs) behaved as a photodynamic nanoswitch to specifically abrogate overactive bypass signaling in resistant tumor cells without interfering with the same signal pathways in normal cells. In representative insulin growth factor-1 receptor (IGF1R) bypass activation-induced gefitinib resistant tumors, CuS NPs upon near-infrared laser irradiation locally elevated reactive oxygen species (ROS) level in tumor cells, leading to the blockage of bypass IGF1R and its downstream AKT/ERK/NF-κB signaling cascades. Consequently, laser-irradiated CuS NPs sensitized tumors to gefitinib treatment and prolonged the survival of mice with no obvious toxicity. Laser-irradiated CuS NPs may serve as a simple and safe nanomedicine strategy to overcome bypass activation-induced gefitinib resistance in a specific and controllable manner and provide insights into the treatment of a myriad of other resistant tumors in the field of cancer therapy.

C‑mannosylation of R‑spondin2 activates Wnt/β‑catenin signaling and migration activity in human tumor cells.

R‑spondin2 (Rspo2), one of the four members of the R‑spondin family of proteins, has agonistic activity in the Wnt/β‑catenin signaling pathway, and it is associated with normal development, as well as disease, such as cancer. The present study focused on the C‑mannosylation of Rspo2, which is a novel and unique type of glycosylation that occurs via a C‑C linkage between the tryptophan residue and an α‑mannose. Although Rspo2 has two putative C‑mannosylation sites at residues Trp150 and Trp153, it had not been reported to date whether these sites are C‑mannosylated. Firstly, results from mass spectrometry demonstrated that Rspo2 was C‑mannosylated at the Trp150 and Trp153 residues. Notably, while this C‑mannosylation of Rspo2 resulted in increased extracellular secretion in human fibrosarcoma HT1080 cells, in other human tumor cell lines it inhibited secretion. However, C‑mannosylation had consistent effects on the activation of Wnt/β‑catenin signaling in PANC1 and MDA‑MB‑231 cells, as well as HT1080 cells. Furthermore, overexpression of wild‑type Rspo2 significantly increased the migratory ability of A549 and HT1080 cells, whereas overexpression of a C‑mannosylation‑defective mutant enhanced migration to a lesser degree. These results suggested that C‑mannosylation of Rspo2 may promote cancer progression and that the inhibition of C‑mannosylation may serve as a potential novel therapeutic approach for cancer therapy.

PC-11 Select targeting of diffuse large B-cell lymphomas using MyD88 small molecule inhibitors

Background: A recurring single amino acid somatic mutation associated with nearly 1/3 of human diffuse large B cell lymphomas (DLBCLs), over 90% of Waldenström macroglobulinemia (WM) and 54% of immunoglobulin M monoclonal gammopathy, has been identified within the myeloid differentiation factor 88 (MyD88). This gain of function single amino acid mutation correlates with tumor cell proliferation and survival involving spontaneous and sustained activation of MyD88-dependent NF-κB and Janus Kinase (JAK) signaling pathways. MyD88 acts as a central signaling adapter for mediating innate and cytokine driven inflammation for the Interleukin-1 (IL-1R) and Toll-like receptors (TLRs). In normal healthy cells, MyD88 is thought to be held in an auto-inhibitory state with its own death and TIR domains fused together in negative self-regulation until activated by appropriate receptor mediated ligand engagement, involving Toll-like or Interleukin-1 ligands. We propose the oncogenic mutation, MyD88L265P located within the TIR domain of MyD88 results in discrete structural changes which releases binding and auto-inhibition of MyD88 death domains resulting in MyDDosome assembly, spontaneous recruitment of IL-1 receptor associated kinases (IRAKs) and sustained signaling. Observation: Recently, CADD derived small molecule compounds which inhibit MyD88 dimer formation have been identified and functionally characterized to protect against Staphylococcal enterotoxin B (SEB) induced death in animal models. Hypothesis: Based on their ability to target MyD88 in protection against Staphylococcal enterotoxin B induced death we hypothesize that CADD derived MyD88 small molecule inhibitors may also be useful therapeutic agents in treating DLBCLs bearing the oncogenic mutation MYD88L265P by inhibiting MyDDosome formation and subsequent recruitment of IL-1 receptor associated kinases. Approach: Using in vitro and in vivo studies we are evaluating MyD88 specific small molecule inhibitors for the ability to inhibit tumor cell proliferation, MyDDsome assembly, IRAK recruitment and signaling in human patient cancer cells OCI Ly3 and OCI Ly19 bearing the oncogenic mutation MYD88L265P. Results: We show (1) MyD88 small molecule inhibitors are able to inhibit cell proliferation of activated human B cell lymphoma cells bearing the MyD88L265P mutation using a MTS cell proliferation assay, (2) Purified recombinant MyD88 and small molecule inhibitors exhibit unique binding chromatograms in comparison to vehicle controls using a thermal shift assay and (3) MyD88 SMIs inhibit LPS activated TLR4-blue cell NF-kB signaling in comparison to the TLR4 specific inhibitor TAK242. We are continuing to biochemically characterize MyD88 small molecule inhibitors as well as test additional human cancer cells bearing oncogenic MyD88 mutations. Conclusions: CADD derived MyD88 specific SMIs previously shown to be effective in protection again microbial infection and death may also be useful in targeting B cell lymphoma cells bearing the MyD88L265P mutation. Future studies defining the molecular mechanism of this MyD88L265P specific mutation associated with nearly one third of human patient tumor isolates will rationally inform and propel development of novel therapeutics to counteract both inflammation as well as tumor cell formation.

Cyclooxygenase-2-Mediated Up-Regulation of Mitochondrial Transcription Factor A Mitigates the Radio-Sensitivity of Cancer Cells.

Mitochondrial transcription factor A (TFAM) regulates mitochondrial biogenesis, and it is a candidate target for sensitizing tumor during therapy. Previous studies identified that increased TFAM expression conferred tumor cells resistance to ionizing radiation. However, the mechanisms on how TFAM are regulated in irradiated tumor cells remain to be explored. In this research, we demonstrated the contribution of cyclooxygenase-2 (COX-2) to enhancing TFAM expression in irradiated tumor cells. Our results showed TFAM was concomitantly up-regulated with COX-2 in irradiated tumor cells. Inhibition of COX-2 by NS-398 blocked radiation-induced expression of TFAM, and prostaglandin E2 (PGE2) treatment stimulated TFAM expression. We next provided evidence that DRP1-mediated mitochondrial fragmentation was a reason for TFAM up-regulation in irradiated cells, by using small interfering RNA (siRNA) and selective inhibitor-targeted DRP1. Furthermore, we proved that p38-MAPK-connected COX-2, and DRP1-mediated TFAM up-regulation. Enhanced phosphorylation of p38 in irradiated tumor cells promoted DRP1 expression, mitochondrial fragmentation, and TFAM expression. NS-398 treatment inhibited radiation-induced p38 phosphorylation, while PGE2 stimulated the activation of p38. The results put forward a mechanism where COX-2 stimulates TFAM expression via p38-mediated DRP1/mitochondrial fragmentation signaling in irradiated tumor cells, which may be of value in understanding how to sensitize cancer cells during radiotherapy.

OVA66 promotes tumour angiogenesis and progression through enhancing autocrine VEGF-VEGFR2 signalling.

BackgroundActivation of autocrine VEGF-VEGFR2 signalling in tumour cells activates cell proliferation, survival, and angiogenesis, all of which are crucial for tumour progression. Ovarian cancer-associated antigen 66 (OVA66) is now known to be overexpressed in multiple tumours and plays a role in tumour development, but the underlying mechanisms has not been fully investigated.MethodsWe employed ovarian and cervical cancer cells and mouse models to detect the role of OVA66 in angiogenesis, growth, and metastasis of cancer cells. Immunofluorescence and western blot were used to determine the function of OVA66 in regulating autocrine VEGF-VEGFR2 signalling. Immunohistochemistry and bioinformatics analysis were used to detect the correlation of OVA66 and VEGF expression.FindingsOVA66 overexpression in the cancer cell lines promoted VEGF secretion, tumour growth and angiogenesis in vitro and in vivo. Conversely, shRNA-mediated OVA66 knockdown had the opposite effects. Mechanistically, OVA66 overexpression was found to boost an autocrine VEGF–VEGFR2 positive-feedback signalling loop in the tumour cells, leading to amplified effect of VEGF on tumour angiogenesis and proliferation and increased migration in vitro and in vivo, respectively. Finally, we identified a significant positive correlation between the expression levels of OVA66 and VEGF in ovarian and cervical cancer specimens, and found that OVA66 was significantly associated with advanced ovarian cancer.InterpretationWe identify a novel function for OVA66 in regulating an autocrine VEGF–VEGFR2 feed-forward signalling loop that promotes tumour progression and angiogenesis.FundThis work was supported by the National Natural Science Foundation of China (81602262); and Excellent Youth Scholar Program of Tongji University (2015KJ062).

First person – Danny Legge

ABSTRACTFirst Person is a series of interviews with the first authors of a selection of papers published in Disease Models & Mechanisms (DMM), helping early-career researchers promote themselves alongside their papers. Danny Legge is first author on ‘BCL-3 promotes a cancer stem cell phenotype by enhancing β-catenin signalling in colorectal tumour cells’, published in DMM. Danny conducted the research described in this article while a PhD student in Professor Ann Williams's lab at Colorectal Tumour Biology Group, School of Cellular and Molecular Medicine, University of Bristol, UK. He is now a postdoc in the lab of Dr Keith Brown at Cancer Epigenetics Laboratory, School of Cellular and Molecular Medicine, University of Bristol, UK, investigating the role of cancer stem cells in colorectal cancer.

A Photoacoustic Probe for the Imaging of Tumor Apoptosis by Caspase-Mediated Macrocyclization and Self-Assembly.

Photoacoustic (PA) imaging shows promise in the sensitive detection of caspase-3 activated in early tumor apoptosis in response to chemotherapy; smart PA probes are thus in high demand. Herein, we report the first smart PA probe (1-RGD) responsive to caspase-3, enabling real-time and high-resolution imaging of tumor apoptosis. 1-RGD is designed to leverage the synergetic effect of active delivery and caspase-3 activation. It is selectively recognized by active caspase-3 to trigger peptide substrate cleavage and biocompatible macrocyclization-mediated self-assembly, leading to an amplified PA imaging signal and prolonged retention in apoptotic tumor cells. Strong, high-resolution PA images are obtained in chemotherapy-induced apoptotic tumors in living mice after intravenous administration with 1-RGD, facilitating sensitive reporting of caspase-3 activity and distribution within tumor tissues.

A Photoacoustic Probe for the Imaging of Tumor Apoptosis by Caspase‐Mediated Macrocyclization and Self‐Assembly

AbstractPhotoacoustic (PA) imaging shows promise in the sensitive detection of caspase‐3 activated in early tumor apoptosis in response to chemotherapy; smart PA probes are thus in high demand. Herein, we report the first smart PA probe (1‐RGD) responsive to caspase‐3, enabling real‐time and high‐resolution imaging of tumor apoptosis. 1‐RGD is designed to leverage the synergetic effect of active delivery and caspase‐3 activation. It is selectively recognized by active caspase‐3 to trigger peptide substrate cleavage and biocompatible macrocyclization‐mediated self‐assembly, leading to an amplified PA imaging signal and prolonged retention in apoptotic tumor cells. Strong, high‐resolution PA images are obtained in chemotherapy‐induced apoptotic tumors in living mice after intravenous administration with 1‐RGD, facilitating sensitive reporting of caspase‐3 activity and distribution within tumor tissues.

Protein Phosphatases—A Touchy Enemy in the Battle Against Glioblastomas: A Review

Glioblastoma (GBM) is the most common malignant tumor arising from brain parenchyma. Although many efforts have been made to develop therapies for GBM, the prognosis still remains poor, mainly because of the difficulty in total resection of the tumor mass from brain tissue and the resistance of the residual tumor against standard chemoradiotherapy. Therefore, novel adjuvant therapies are urgently needed. Recent genome-wide analyses of GBM cases have clarified molecular signaling mechanisms underlying GBM biology. However, results of clinical trials targeting phosphorylation-mediated signaling have been unsatisfactory to date. Protein phosphatases are enzymes that antagonize phosphorylation signaling by dephosphorylating phosphorylated signaling molecules. Recently, the critical roles of phosphatases in the regulation of oncogenic signaling in malignant tumor cells have been reported, and tumorigenic roles of deregulated phosphatases have been demonstrated in GBM. However, a detailed mechanism underlying phosphatase-mediated signaling transduction in the regulation of GBM has not been elucidated, and such information is necessary to apply phosphatases as a therapeutic target for GBM. This review highlights and summarizes the phosphatases that have crucial roles in the regulation of oncogenic signaling in GBM cells.

Design, synthesis and biological evaluation of pyridone-aminal derivatives as MNK1/2 inhibitors.

Excessive phosphorylation of eukaryotic translation initiation factor 4E (eIF4E) plays a major role in the dysregulation of mRNA translation and the activation of tumor cell signaling. eIF4E is exclusively phosphorylated by mitogen-activated protein kinase interacting kinases 1 and 2 (MNK1/2) on Ser209. So, MNK1/2 inhibitors could decrease the level of p-eIF4E and regulate tumor-associated signaling pathways. A series of pyridone-aminal derivatives were synthesized and evaluated as MNK1/2 inhibitors. Several compounds exhibited great inhibitory activity against MNK1/2 and selected compounds showed moderate to excellent anti-proliferative potency against hematologic cancer cell lines. In particular, compound 42i (MNK1 IC50 = 7.0 nM; MNK2 IC50 = 6.1 nM) proved to be the most potent compound against TMD-8 cell line with IC50 value of 0.91 μM. Furthermore, 42i could block the phosphorylation level of eIF4E in CT-26 cell line, and 42i inhibited the tumor growth of CT-26 allograft model significantly. These results indicated that compound 42i was a promising MNK1/2 inhibitor for the potent treatment of colon cancer.