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YAP1-mediated pancreatic stellate cell activation inhibits pancreatic cancer cell proliferation

期刊: CANCER LETTERS, 2019; 462 ()

Pancreatic stellate cells (PSCs) are activated in pancreatic ductal adenocarcinoma (PDAC) and are responsible for dense desmoplastic stroma. Yes-associated protein 1 (YAP1) can induce cancer-associated fibroblast activation in liver and breast tumors, but its effect on PSCs is unknown. In the present study, we determined that YAP1 was highly expressed in the nuclei of PDAC-derived activated PSCs. RNAi-mediated or pharmacological inhibition of YAP1 led to PSC deactivation. In addition, YAP1 stimulated the expression of secreted protein acidic and cysteine rich (SPARC) in PSCs, which was inhibited by RUNX1. SPARC secreted from PSCs inhibited pancreatic cancer cell (PCC) proliferation. High expression of nuclear YAP1 in tumor stroma was significantly correlated with SPARC expression and fibrosis degree in human PDAC tissues. Our study revealed a critical role for YAP1 in the regulation of PSC activation and paracrine signaling. Our findings provide insights into a novel rationale for targeting YAP1 to reprogram the PDAC microenvironment.

JIF:6.51

Lost or Forgotten: The nuclear cathepsin protein isoforms in cancer

期刊: CANCER LETTERS, 2019; 462 ()

While research into the role of cathepsins has been progressing at an exponential pace over the years, research into their respective isoform proteins has been less frenetic. In view of the functional and biological potential of such protein isoforms in model systems for cancer during their initial discovery, much later they have offered a new direction in the field of cathepsin basic and applied research. Consequently, the analysis of such isoforms has laid strong foundations in revealing other important regulatory aspects of the cathepsin proteins in general. In this review article, we address these key aspects of cathepsin isoform proteins, with particular emphasis on how they have shaped what is now known in the context of nuclear cathepsin localization and what potential these hold as nuclear-based therapeutic targets in cancer.

JIF:6.51

Adoptive CD8(+) T cell therapy against cancer:Challenges and opportunities

期刊: CANCER LETTERS, 2019; 462 ()

Cancer immunotherapy is a new and promising option for cancer treatment. Unlike traditional chemo- and radiotherapy, immunotherapy actives host immune system to attack malignancies, and this potentially offers long-term protection from recurrence with less toxicity in comparison to conventional chemo- and radiation therapy. In adoptive CD8(+) T cell therapy (ACT), large numbers of tumor-specific T cells are sourced from patients and expanded in vitro and infused back to patients. T cells can be expanded from naturally-induced tumor-specific CD8(+) T cells isolated from tumor infiltrating lymphocytes (TIL) or genetically-modified autologous circulating CD8(+) T cells. The engineered T cells expressed tumor-specific antigen receptors including chimeric antigen receptors (CARs) and T cell receptors (TCRs), prepared from cultured B and T cell clones, respectively. The most successful ACT, anti-CD19 chimeric antigen receptor T (CAR-T) cell therapy directed against B cell lymphoma, is already approved for use based on evidence of efficacy. Efficacy of solid tumors is not yet forthcoming. This review summarizes current technology developments using ACT in clinical trials. In this review, differences between various ACT approaches are discussed. Furthermore, resistance factors in the tumor microenvironment are also considered, as are immune related adverse effects, critical clinic monitoring parameters and potential mitigation approaches.

JIF:6.51

IL-10 knockdown with siRNA enhances the efficacy of Doxorubicin chemotherapy in EBV-positive tumors by inducing lytic cycle via PI3K/p38 MAPK/NF-kappa B pathway

期刊: CANCER LETTERS, 2019; 462 ()

High levels of IL-10 expression in Epstein-Barr virus (EBV) associated tumors have been reported and it is likely to be important for maintaining EBV latency and EBV-associated tumors. The switch from the latent form of EBV to the lytic form in tumor cells can lead to tumor cell lysis. Here, we found that knockdown of IL-10 induced EBV lytic replication. Subsequently, we demonstrated that IL-10 knockdown activated BZLF1 promoter through PI3K-p38 MAPK-NF-kappa B signaling pathway. Interestingly, we verified that VEGF-A was required for IL-10 knockdown to activate PI3K signaling and the accompanying EBV lytic induction. Exogenous recombinant human VEGF-A induced PI3K activation and EBV lytic infection, and inhibition of VEGF-A signaling prevented the PI3K/AKT phosphorylation and EBV reactivation responded to IL-10 knockdown. Most importantly, IL-10 knockdown synergized with chemotherapeutic agent Doxorubicin to kill EBV associated tumor cells in vitro and repress EBV-positive tumor growth in vivo. Our results suggest that inhibition of IL-10 has the potential to serve as a new supplemental strategy for the treatment of EBV-associated tumors.

JIF:6.51

HIF-1 alpha-induced miR-23a similar to 27a similar to 24 cluster promotes colorectal cancer progression via reprogramming metabolism

期刊: CANCER LETTERS, 2019; 440 ()

Tumor cells switch metabolic profile from oxidative phosphorylation to glycolysis in a hypoxic environment for survival and proliferation. The mechanisms governing this metabolic switch, however, remain incompletely understood. Here, we show that three miRNAs in the miR-23a similar to 27a similar to 24 cluster, miR-23a, miR-27a and miR-24, are the most upregulated miRNA cluster in colorectal cancer (CRC) under hypoxia. Gain- and loss-of-function assays, a human glucose metabolism array and gene pathway analyses confirm that HIF-1 alpha-induced miR23a similar to 27a similar to 24 cluster collectively regulate glucose metabolic network through regulating various metabolic pathways and targeting multiple tricarboxylic acid cycle (TCA)-related genes. In specific, miR-24/VHL/HIF-1 alpha in CRC form a double-negative feedback loop, which in turn, promotes the cellular transition to the 'high HIF-1 alpha/miR-24 and low VHL' state and facilitates cell survival. Our findings reveal that the miR-23a similar to 27a similar to 24 cluster is critical regulator switching CRC metabolism from oxidative phosphorylation to glycolysis, and controlling their expression can suppress colorectal cancer progression.

JIF:6.51

Adipose tissue-derived mesenchymal stem cells cultured at high density express IFN-beta and TRAIL and suppress the growth of H460 human lung cancer cells

期刊: CANCER LETTERS, 2019; 440 ()

Although mesenchymal stem cells (MSCs) have been reported to inhibit tumor growth, the mechanism controlling this tumor suppression function is unclear. Here, we report that high-density (40,000 cells/cm(2)) cultured adipose tissue-derived MSCs (40K-ASCs) expressed interferon (IFN)-beta and tumor necrosis factor-related apoptosis-inducing ligand (TRAIL); we also found that serum deprivation during cell culture induced the expression of IFN-beta and TRAIL. In addition, the mRNA expression of IFN-beta, but not TRAIL, was increased during the washing step required for the transplantation of normal-density (5000 cells/cm(2)) cultured ASCs (5K-ASCs). When the human lung cancer cell line H460 was co-cultured with 40K-ASCs, necrotic cell death was dramatically increased in vitro. When ASCs were injected after four washes, both 5K-ASCs and 40K-ASCs substantially reduced tumor weight in H460-derived cancer animal models. These results suggest that serum deprivation during the culture of 40K-ASCs or during the washing step of 5K-ASCs can induce IFN-beta and/or TRAIL expression, ultimately leading to the tumor suppression capability of ASCs.

JIF:6.51

Loss of TMEM126A promotes extracellular matrix remodeling, epithelial-to-mesenchymal transition, and breast cancer metastasis by regulating mitochondrial retrograde signaling

期刊: CANCER LETTERS, 2019; 440 ()

TMEM126A is a mitochondrial transmembrane protein, and its functions in breast cancer progression remain unclear. In this study, via the iTRAQ assay using primary and metastatic breast cancer cell models, we found that TMEM126A expression decreased in metastatic cells. We further confirmed that low TMEM126A expression correlated with tumor progression and poor prognosis in patients. The downregulation of TMEM126A in breast cancer cell lines significantly enhanced the metastatic properties in vitro and in vivo, whereas its overexpression decreased the metastatic potential of cell lines. Mechanistic studies based on RNA-sequencing indicated that TMEM126A might regulate cell metastasis via ECM-receptor interaction, focal adhesions, and actin cytoskeleton, among other processes. Furthermore, the loss of TMEM126A activated extracellular matrix (ECM) remodeling and promoted epithelial-to-mesenchymal transition (EMT). Moreover, TMEM126A silencing induced reactive oxygen species (ROS) production and mitochondrial membrane potential depolarization. The ROS scavengers reversed ECM remodeling and EMT mediated by TMEM126A. Collectively, our findings show that the loss of TMEM126A induces mitochondrial dysfunction and subsequently metastasis by activating ECM remodeling and EMT. These findings suggest that TMEM126A is a novel suppressor of metastasis and that it can be a potential prognostic indicator for patients with breast cancer.

JIF:6.51

Primate-specific miR-944 activates p53-dependent tumor suppression in human colorectal cancers

期刊: CANCER LETTERS, 2019; 440 ()

As cancers with a high incidence rate, colorectal cancers are a main cause of cancer-related death. MicroRNAs are often deregulated in cancers. The primate-specific miR-944, located in a p63 intron, is known to be highly expressed in patients exhibiting low colorectal cancer recurrence rates. However, the biological functions of miR-944 in colorectal cancers remain unclear. In this study, we found that miR-944 was downregulated in colorectal cancer tissues, and inhibited cancer cell growth in a xenograft mouse model. The overexpression of miR-944 caused G1 phase arrest and increased p53 expression in cancer cells. p53 stability was enhanced by miR-944s targeting E3 ligases COP1 and MDM2. Overexpression of COP1 and MDM2 restored cell growth inhibition caused by miR-944. Taken together, our results suggest that miR-944 acts as a potential tumor suppressor in colorectal cancers through the ubiquitin-proteasome system.

JIF:6.51

Major vault protein is a direct target of Notch1 signaling and contributes to chemoresistance in triple-negative breast cancer cells

期刊: CANCER LETTERS, 2019; 440 ()

Resistance to chemotherapy remains a significant problem in the treatment of breast cancer, especially for triple negative breast cancer (TNBC), in which standard systemic therapy is currently limited to chemotherapeutic agents. Our study aimed to better understand the molecular mechanisms that lead to failure of chemotherapy in TNBC. Herein, we observed elevated expression of Notch1 and major vault protein (MVP) in MDA-MB-231DDPR cells compared to their parental counterparts. We demonstrated that Notch1 could positively regulate the expression of MVP. Also, Notch1 intracellular domain (ICD) was capable of binding to CBF-1 on the promoter of MVP to drive its transcription, resulting in activation of AKT pathway and promoting the progress of epithelial to mesenchymal transition (EMT). Conversely, silencing of Notch1 and MVP suppressed AKT pathway, reduced EMT and enhanced the sensitivity of TNBC cells to cisplatin and doxorubicin. Survival analysis indicated that the MVP was closely related to shorter recurrence-free survival (RFS) in patients with TNBC. Collectively, this study provides evidence that Notch1 activates AKT pathway and promotes EMT partly through direct activation of MVP. Targeting Notch1/MVP pathway appears to have potential in overcoming chemoresistance in TNBC.

JIF:6.51

Identification of Smac mimetics as novel substrates for p-glycoprotein

期刊: CANCER LETTERS, 2019; 440 ()

Multidrug resistance (MDR) in cancer patients undergoing chemotherapy is preventing effective treatment of multiple cancer types including pediatric tumors. Resistance to chemotherapeutic drugs in cancer cells is frequently associated with high expression of p-glycoprotein, a transporter in the plasma membrane that can mediate cellular drug export. Here, we generated pediatric cancer cells with acquired resistance to the chemotherapeutic drug vincristine (VCR). In these cells, acquired resistance is associated with increased expression of p-glycoprotein. VCR-resistant cells display an MDR phenotype and have acquired resistance to multiple other chemotherapeutic drugs including doxorubicin (DOXO) and etoposide (ETO). Notably, we discovered that these cells also display cross-resistance with several Smac mimetics, a novel class of experimental cancer therapeutics designed to induce apoptosis by inhibiting Inhibitor of Apoptosis (IAP) proteins. Resistance to Smac mimetics is reversible in the presence of p-glycoprotein inhibitors, highlighting Smac mimetics as novel substrates for p-glycoprotein. The identification of Smac mimetics as substrates for p-glycoproteins may influence the design of future clinical trials to prevent usage of Smac mimetics in the context of MDR or, alternatively, combine Smac mimetics with p-glycoprotein inhibitors to maximize their efficiency.

JIF:6.51

Tumor-associated macrophages promote lung metastasis and induce epithelial-mesenchymal transition in osteosarcoma by activating the COX-2/STAT3 axis

期刊: CANCER LETTERS, 2019; 440 ()

Osteosarcoma (OS) is a common, malignant musculoskeletal tumor in young people. Neoadjuvant chemotherapy has improved the survival of osteosarcoma patients but with limited benefit due to metastasis. Tumor-associated macrophages (TAMs) are involved in various mechanisms of tumor biology, which include oncogenesis, drug resistance, and tumor immune escape, as well as tumor metastasis. In this study, we proved that TAMs possess the ability to promote OS cell migration and invasion by upregulating COX-2, MMP9, and phosphorylated STAT3 and to induce the epithelial-mesenchymal transition (EMT). This evidence has also been verified in a tumor bearing animal model, and in OS patients. Furthermore, we observed the anti-metastasis effect of COX-2 inhibition by repressing COX-2 expression, EMT-activating transcription factors and the STAT3 pathway, both in vitro and in vivo. We propose that TAMs promote OS metastasis and invasion by activating the COX-2/STAT3 axis and EMT. These findings suggest that TAMs and COX-2 may be potential targets for future anti-metastasis therapy.

JIF:6.51

Human UTP14a promotes colorectal cancer progression by forming a positive regulation loop with c-Myc

期刊: CANCER LETTERS, 2019; 440 ()

Nucleolar protein hUTP14a is required for 18S rRNA processing and promotes p53 degradation. Here, we report that hUTP14a stabilizes c-Myc in colorectal cancer (CRC) progression. Firstly, nucleolar hUTP14a is upregulated in human CRC tissues. Mass spectrometry analysis identified c-Myc and its deubiquitinase ubiquitin-specific protease 36 (USP36) in the hUTP14a-specific complex. Importantly, hUTP14a interacts with c-Myc and protects c-Myc from ubiquitination and degradation in a USP36-dependent way. We further demonstrate that hUTP14a forms a complex with USP36/Fbw7 gamma to inhibit Fbw7 gamma-mediated c-Myc degradation. Ectopic expression of Flagh-UTP14a enriches c-Myc in the nucleolus, indicating hUTP14a stabilizes c-Myc in the nucleolus. Interestingly, c-Myc activates transcription of hUTP14a. Knockdown of hUTP14a by short hairpin RNA inhibits tumor growth and decreases c-Myc levels in mouse xenografts. Significantly, nucleolar hUTP14a and c-Myc are co-upregulated in human CRC tissues, and this co-upregulation indicates poor prognosis of CRC patients. Thus, disruption of hUTP14a-c-Myc regulation may provide a potential therapeutic strategy for a subset of CRC patients.

JIF:6.51

Carbohydrate-based adjuvants activate tumor-specific Th1 and CD8(+) T-cell responses and reduce the immunosuppressive activity of MDSCs

期刊: CANCER LETTERS, 2019; 440 ()

Toll-like receptors (TLRs) and C-type lectin receptors (CLRs) contribute to antigen capture, uptake, presentation and activation of immune responses. We recently developed a new and lymph node (LN) targeting adjuvant (D-CpG) by chemical conjugation type B CpG DNA with FDA-approved dextran polymer for lymph node imaging. To elucidate the possible antitumor mechanisms of this adjuvant, prophylaxis and therapeutic models of melanoma were used in this study. Our results showed that D-CpG was an efficient adjuvant of protein-based tumor vaccine in both prophylaxis and therapeutic models. It enhanced the tumor-specific Th1 and CTL, responses. It also facilitated the tumor infiltration of the T cells and promoted IFN gamma and TNF alpha production of both CD4(+) and CD8(+) T cells. In therapeutic model, D-CpG included tumor vaccine decreased the percentage of CD11b(+)Gr1(low+) MDSCs in spleen and inhibited their infiltration in tumor microenvironments. Administration of the D-CpG included vaccine significantly inhibited lung metastasis of the tumor through similar mechanisms. In conclusion, D-CpG used as tumor vaccine adjuvant can enhance both Th1 and CTL responses and inhibit CD11b(+)Gr1(low+) MDSCs, which may have general applicability to the development of vaccines against tumors.

JIF:6.51

Mitosis inhibitors in anticancer therapy: When blocking the exit becomes a solution

期刊: CANCER LETTERS, 2019; 440 ()

Current microtubule-targeting agents (MTAs) remain amongst the most important antimitotic drugs used against a broad range of malignancies. By perturbing spindle assembly, MTAs activate the spindle assembly checkpoint (SAC), which induces mitotic arrest and subsequent apoptosis. However, besides toxic side effects and resistance, mitotic slippage and failure in triggering apoptosis in various cancer cells are limiting factors of MTAs efficacy. Alternative strategies to target mitosis without affecting microtubules have, thus, led to the identification of small molecules, such as those that target spindle Kinesins, Aurora and Polo-like kinases. Unfortunately, these so-called second-generation of antimitotics, encompassing mitotic blockers and mitotic drivers, have failed in clinical trials. Our recent understanding regarding the mechanisms of cell death during a mitotic arrest pointed out apoptosis as the main variable, providing an opportunity to control the cell fates and influence the effectiveness of antimitotics. Here, we provide an overview on the second-generation of antimitotics, and discuss possible strategies that exploit SAC activity, mitotic slippage/exit and apoptosis induction, in order to improve the efficacy of anticancer strategies that target mitosis.

JIF:6.51

Inhibition of BTF3 sensitizes luminal breast cancer cells to PI3K alpha inhibition through the transcriptional regulation of ER alpha

期刊: CANCER LETTERS, 2019; 440 ()

Selective phosphatidylinositol 3 kinase (PI3K) inhibitors are being actively tested in clinical trials for ER alpha-positive (ER +) breast cancer due to the presence of activating PIK3CA mutations. However, recent studies have revealed that increased ER alpha transcriptional activity limits the efficacy of PI3K inhibitor monotherapy for ER + breast cancers. Herein, we report the identification of BTF3 as an oncogenic transcription factor that regulates ER alpha expression in luminal breast cancers. Our TCGA analysis reveals high expression levels of BTF3 in luminal/ER + breast cancer and cell line models harboring ERa overexpression. Concordantly, BTF3 expression is highly and strongly associated with ESR1 expression in multiple breast cancer cohorts. We further show that BTF3 promotes the proliferation, survival and migration of ER + breast cancer cells by modulating ESR1 expression and ER alpha-dependent transcription. Moreover, BTF3 knockdown sensitizes ER + breast cancer cells to the PI3K alpha inhibitor BYL-719 in both in vitro and in vivo models. Together, our findings highlight a novel role of BTF3 in modulation of ER alpha-dependent transcriptional activity and its potential as a predictive marker for the response to PI3K-targeted therapy in ER + breast cancer.

JIF:6.51

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