Signal transducer and activator of transcription 3 activation promotes invasive growth of colon carcinomas through matrix metalloproteinase induction

Periodontitis increases the risk of gastrointestinal dysfunction: an update on the plausible pathogenic molecular mechanisms

Periodontitis is an immuno-inflammatory disease of the soft tissues surrounding the teeth. Periodontitis is linked to many communicable and non-communicable diseases such as diabetes, cardiovascular disease, rheumatoid arthritis, and cancers. The oral-systemic link between periodontal disease and systemic diseases is attributed to the spread of inflammation, microbial products and microbes to distant organ systems. Oral bacteria reach the gut via swallowed saliva, whereby they induce gut dysbiosis and gastrointestinal dysfunctions. Some periodontal pathogens like Porphyromonas. gingivalis, Klebsiella, Helicobacter. Pylori, Streptococcus, Veillonella, Parvimonas micra, Fusobacterium nucleatum, Peptostreptococcus, Haemophilus, Aggregatibacter actinomycetomcommitans and Streptococcus mutans can withstand the unfavorable acidic, survive in the gut and result in gut dysbiosis. Gut dysbiosis increases gut inflammation, and induce dysplastic changes that lead to gut dysfunction. Various studies have linked oral bacteria, and oral-gut axis to various GIT disorders like inflammatory bowel disease, liver diseases, hepatocellular and pancreatic ductal carcinoma, ulcerative colitis, and Crohn's disease. Although the correlation between periodontitis and GIT disorders is well established, the intricate molecular mechanisms by which oral microflora induce these changes have not been discussed extensively. This review comprehensively discusses the intricate and unique molecular and immunological mechanisms by which periodontal pathogens can induce gut dysbiosis and dysfunction.

The Janus kinase 1 is critical for pancreatic cancer initiation and progression

Interleukin-6 (IL-6)-class inflammatory cytokines signal through the Janus tyrosine kinase (JAK)/signal transducer and activator of transcription (STAT) pathway and promote the development of pancreatic ductal adenocarcinoma (PDAC); however, the functions of specific intracellular signaling mediators in this process are less well defined. Using a ligand-controlled and pancreas-specific knockout in adult mice, we demonstrate in this study that JAK1 deficiency prevents the formation of KRASG12D-induced pancreatic tumors, and we establish that JAK1 is essential for the constitutive activation of STAT3, whose activation is a prominent characteristic of PDAC. We identify CCAAT/enhancer binding protein δ (C/EBPδ) as a biologically relevant downstream target of JAK1 signaling, which is upregulated in human PDAC. Reinstating the expression of C/EBPδ was sufficient to restore the growth of JAK1-deficient cancer cells as tumorspheres and in xenografted mice. Collectively, the findings of this study suggest that JAK1 executes important functions of inflammatory cytokines through C/EBPδ and may serve as a molecular target for PDAC prevention and treatment.

Triptolide, a Cancer Cell Proliferation Inhibitor, Causes Zebrafish Muscle Defects by Regulating Notch and STAT3 Signaling Pathways

Triptolide is a natural compound in herbal remedies with anti-inflammatory and anti-proliferative properties. We studied its effects on critical signaling processes within the cell, including Notch1 and STAT3 signaling. Our research showed that triptolide reduces cancer cell proliferation by decreasing the expression of downstream targets of these signals. The levels of each signal-related protein and mRNA were analyzed using Western blot and qPCR methods. Interestingly, inhibiting one signal with a single inhibitor alone did not significantly reduce cancer cell proliferation. Instead, MTT assays showed that the simultaneous inhibition of Notch1 and STAT3 signaling reduced cell proliferation. The effect of triptolide was similar to a combination treatment with inhibitors for both signals. When we conducted a study on the impact of triptolide on zebrafish larvae, we found that it inhibited muscle development and interfered with muscle cell proliferation, as evidenced by differences in the staining of myosin heavy chain and F-actin proteins in confocal fluorescence microscopy. Additionally, we noticed that inhibiting a single type of signaling did not lead to any significant muscle defects. This implies that triptolide obstructs multiple signals simultaneously, including Notch1 and STAT3, during muscle development. Chemotherapy is commonly used to treat cancer, but it may cause muscle loss due to drug-related adverse reactions or other complex mechanisms. Our study suggests that anticancer agents like triptolide, inhibiting essential signaling pathways including Notch1 and STAT3 signaling, may cause muscle atrophy through anti-proliferative activity.

Oligonucleotide-Based Therapeutics for STAT3 Targeting in Cancer-Drug Carriers Matter

High expression and phosphorylation of signal transducer and transcription activator 3 (STAT3) are correlated with progression and poor prognosis in various types of cancer. The constitutive activation of STAT3 in cancer affects processes such as cell proliferation, apoptosis, metastasis, angiogenesis, and drug resistance. The importance of STAT3 in cancer makes it a potential therapeutic target. Various methods of directly and indirectly blocking STAT3 activity at different steps of the STAT3 pathway have been investigated. However, the outcome has been limited, mainly by the number of upstream proteins that can reactivate STAT3 or the relatively low specificity of the inhibitors. A new branch of molecules with significant therapeutic potential has emerged thanks to recent developments in the regulatory function of non-coding nucleic acids. Oligonucleotide-based therapeutics can silence target transcripts or edit genes, leading to the modification of gene expression profiles, causing cell death or restoring cell function. Moreover, they can reach untreatable targets, such as transcription factors. This review briefly describes oligonucleotide-based therapeutics that found application to target STAT3 activity in cancer. Additionally, this review comprehensively summarizes how the inhibition of STAT3 activity by nucleic acid-based therapeutics such as siRNA, shRNA, ASO, and ODN-decoy affected the therapy of different types of cancer in preclinical and clinical studies. Moreover, due to some limitations of oligonucleotide-based therapeutics, the importance of carriers that can deliver nucleic acid molecules to affect the STAT3 in cancer cells and cells of the tumor microenvironment (TME) was pointed out. Combining a high specificity of oligonucleotide-based therapeutics toward their targets and functionalized nanoparticles toward cell type can generate very efficient formulations.

Inhibition of Na+/H+ exchanger (NHE) 7 by 5-(N-ethyl-N-isopropyl)-Amiloride displays anti-cancer activity in non-small cell lung cancer by disrupting cancer stem cell activity and downregulating PD-L1 expression

The alkaline intracellular environment of cancer cells is critical for cell proliferation and controlled by various plasma membrane transporters including Na+/H+ exchangers (NHEs). NHEs can also mediate cell behavior by regulating signaling transduction. In this study, we investigated the role of NHE7 in cancer stem cell (CSC) activity in non-small cell lung cancer (NSCLC) cells and the potential therapeutic implications of targeting NHE7 and the associated immune checkpoint molecule PD-L1. By analyzing the database from The Cancer Genome Atlas, we found a positive correlation between SLC9A7 mRNA levels (the gene encoding NHE7) and poor overall survival in lung adenocarcinoma patients. Using 5-(N-ethyl-N-isopropyl)-Amiloride (EIPA) to inhibit NHE7 activity, we observed disrupted cell cycle progression and suppressed NSCLC cell proliferation without inducing apoptosis. Furthermore, EIPA demonstrated a suppressive effect on CSC activity, evidenced by decreased tumorsphere numbers and inhibition of CSC markers such as ALDH1A2, ABCG2, CD44, and CD133. Flow cytometric analysis revealed that EIPA treatment or NHE7 knockdown in NSCLC cells led to downregulated PD-L1 expression, associated with inhibited STAT3 activity. Interestingly, EIPA's CSC-targeting activity was preferentially observed in NSCLC cells overexpressing BMI1, while increased PD-L1 expression was detected in BMI1-overexpressing NSCLC cells. Our findings suggest that targeting NHE7 with inhibitors like EIPA may have therapeutic potential in NSCLC treatment by disrupting cell cycle progression and suppressing CSC activity. The observed increase in PD-L1 expression in BMI1-overexpressing NSCLC cells upon EIPA treatment highlights the potential benefit of combining NHE7 inhibitors with anti-PD-L1 agents as a promising new therapeutic strategy for NSCLC.

Interplay between Signaling Pathways and Tumor Microenvironment Components: A Paradoxical Role in Colorectal Cancer

The study of the tumor microenvironment (TME) has become an important part of colorectal cancer (CRC) research. Indeed, it is now accepted that the invasive character of a primary CRC is determined not only by the genotype of the tumor cells, but also by their interactions with the extracellular environment, which thereby orchestrates the development of the tumor. In fact, the TME cells are a double-edged sword as they play both pro- and anti-tumor roles. The interaction of the tumor-infiltrating cells (TIC) with the cancer cells induces the polarization of the TIC, exhibiting an antagonist phenotype. This polarization is controlled by a plethora of interconnected pro- and anti-oncogenic signaling pathways. The complexity of this interaction and the dual function of these different actors contribute to the failure of CRC control. Thus, a better understanding of such mechanisms is of great interest and provides new opportunities for the development of personalized and efficient therapies for CRC. In this review, we summarize the signaling pathways linked to CRC and their implication in the development or inhibition of the tumor initiation and progression. In the second part, we enlist the major components of the TME and discuss the complexity of their cells functions.

Napabucasin Plus FOLFIRI in Patients With Previously Treated Metastatic Colorectal Cancer: Results From the Open-Label, Randomized Phase III CanStem303C Study

PURPOSE

Napabucasin is an investigational, orally administered reactive oxygen species generator bioactivated by intracellular antioxidant NAD(P)H:quinone oxidoreductase 1 that has been evaluated in various solid tumors, including metastatic colorectal cancer (mCRC). Phosphorylated signal transducer and activator of transcription 3 (pSTAT3) is hypothesized to predict response in napabucasin-treated patients with mCRC.

PATIENT AND METHODS

In the multi-center, open-label, phase III CanStem303C (NCT02753127) study, adults with histologically confirmed mCRC that progressed on first-line fluoropyrimidine plus oxaliplatin ± bevacizumab were randomized to twice-daily napabucasin plus FOLFIRI (napabucasin) or FOLFIRI alone (control). The primary endpoint was overall survival (OS) in the general study population and in patients with pSTAT3-positive tumors (biomarker-positive).

RESULTS

In the general study population (napabucasin, n = 624; control, n = 629), median OS was 14.3 months for napabucasin and 13.8 months for control (hazard ratio [HR], 0.976, one-sided P = .74). Overall, 44% of patients were biomarker-positive (napabucasin, n = 275; control, n = 272). In the biomarker-positive population, median OS was 13.2 months for napabucasin and 12.1 months for control (HR, 0.969; one-sided P > .99). In the control arm, median OS was shorter for biomarker-positive versus biomarker negative patients (12.1 vs. 18.5 months; HR, 1.518; nominal 2-sided P = .0002). The most common treatment-emergent adverse events (TEAEs) were diarrhea (napabucasin, 84.6%; control, 53.9%), nausea (60.5%, 50.5%), vomiting (41.2%, 29.3%), and abdominal pain (41.0%, 25.2%). Grade ≥3 TEAEs occurred in 73.8% of napabucasin-treated and 66.7% of control-treated patients, most commonly diarrhea (21.2%, 7.0%), neutrophil count decreased (13.7%, 19.2%), and neutropenia (13.3%, 15.2%). Safety was similar in biomarker-positive patients.

CONCLUSION

In patients with previously treated mCRC, adding napabucasin to FOLFIRI did not improve OS. Results from the control arm indicate that pSTAT3 is an adverse prognostic factor in mCRC.

Phenolic from apple blossom "Hongro" inhibits the expression of proteins related to melanogenesis in B16F10 melanoma cells

This study aimed to assess apple blossom extracts as potential natural whitening agents due to their ability to inhibit melanogenesis. Ethanol extracts of apple blossom (ABE) were assessed for biological activity in the B16F10 mouse melanoma cell line. ABE toxicity was assessed by thiazolyl blue tetrazolium bromide (MTT) assay. Levels of melanogenic enzyme expression in response to ABE supplementation were assessed by western blotting. Also assessed purified kaempferol, one of the phenolic compounds extracted from apple blossom, was evaluated using western blot analysis. The expression levels of cellular tyrosinase, microphthalmia-associated transcription factor (MITF), tyrosinase-related protein (TRP)-1, and TRP-2 proteins related to melanogenesis decreased in a dose-dependent manner with ABE treatment of cells. Using nuclear magnetic resonance, we identified kaempferol in the ABE. Treatment of cells with purified kaempferol decreased the expression levels of tyrosinase and the MITF protein to a similar degree as that observed with ABE treatment. This suggests that the efficacy of melanogenesis-related inhibition demonstrated by ABE was due to kaempferol. ABE has an inhibitive effect on melanogenic enzymes and potentially can be applied to functional foods and cosmetics having a whitening effect as a natural material.

Spatial-Frequency dual-branch attention model for determining KRAS mutation status in colorectal cancer with T2-weighted MRI

BACKGROUND AND OBJECTIVE

Identifying the KRAS mutation status accurately in medical images is very important for the diagnosis and treatment of colorectal cancer. Despite the substantial progress achieved by existing methods, it remains challenging due to limited annotated dataset, large intra-class variances, and a high degree of inter-class similarities.

METHODS

To tackle these challenges, we propose a spatial-frequency dual-branch attention model (SF-DBAM) to determine the KRAS mutation status of colorectal cancer patients using a limited T2-weighted MRI dataset. The dataset contains 169 wild-type patients (2151 images) and 137 mutation-type patients (1666 images). The first branch utilizes part of the pre-trained Xception model to capture spatial-domain information and alleviate the small-scale dataset problem. The second branch builds frequency-domain information into cube columns using block-based discrete cosine transform and channel rearrangement. Then the cube columns are fed into convolutional long short-term memory (convLSTM) to explore the effective information between the reconstructed frequency-domain channels. Also, we design a channel enhanced attention module (CEAM) at the end of each branch to make them focus on the lesion areas. Finally, we concatenate the two branches and output the classified results through fully connected layers.

RESULTS

The proposed method achieves 88.03% overall accuracy with AUC of 94.27% and specificity of 90.75% in 10-fold cross-validation, which is better than the current non-invasive methods for determining KRAS mutation status.

CONCLUSIONS

We believe that the proposed method can assist physicians to diagnose the KRAS mutation status in patients with colorectal cancer, and other medical problems can benefit from the spatial and frequency domains information.

MicroRNA 452 regulates IL20RA-mediated JAK1/STAT3 pathway in inflammatory colitis and colorectal cancer

OBJECTIVE

MicroRNAs are a class of small, non-coding RNAs that play a key role in several biological and molecular processes, including tumorigenesis. We previously identified that MIR452 is upregulated in both colorectal cancer (CRC) and colitis. However, the functional mechanisms of MIR452 and its target genes in CRC and colitis are not well understood. So, we hypothesize that MIR452 can influence CRC and DSS-induced colitis model through the regulation of IL20RA and its downstream JAK-STATs signaling pathway.

METHODS

We used a luciferase reporter assay to confirm the effect of MIR452 on IL20RA expression. The protein and mRNA expression of a target gene and its associated molecules were measured by western blot, quantitative RT-PCR, and immunohistochemistry.

RESULTS

We found that the IL20RA was a direct target gene of MIR452. Overexpression of MIR452 in CRC cell lines significantly decreased IL20RA and its downstream Janus kinase 1 (JAK1), Signal transducer and activator of transcription 1 (STAT1) and STAT3. Knockdown of IL20RA in CRC cell lines by IL20RA gene silencing also decreased the expression of IL20RA, JAK1, and STAT3, but not of STAT1.

CONCLUSION

Our results suggest that MIR452 regulates STAT3 through the IL20RA-mediated JAK1 pathway, but not STAT1. Overall, MIR452 acts as tumor suppressor in human CRC and in a mouse colitis model. These findings suggest that MIR452 is a promising therapeutic target in the treatment of cancer and colitis.

Emerin Represses STAT3 Signaling through Nuclear Membrane-Based Spatial Control

Emerin is the inner nuclear membrane protein involved in maintaining the mechanical integrity of the nuclear membrane. Mutations in EMD encoding emerin cause Emery–Dreifuss muscular dystrophy (EDMD). Evidence is accumulating that emerin regulation of specific gene expression is associated with this disease, but the exact function of emerin has not been fully elucidated. Here, we show that emerin downregulates Signal transducer and activators of transcription 3 (STAT3) signaling, activated exclusively by Janus kinase (JAK). Deletion mutation experiments show that the lamin-binding domain of emerin is essential for the inhibition of STAT3 signaling. Emerin interacts directly and co-localizes with STAT3 in the nuclear membrane. Emerin knockdown induces STAT3 target genes Bcl2 and Survivin to increase cell survival signals and suppress hydrogen peroxide-induced cell death in HeLa cells. Specifically, downregulation of BAF or lamin A/C increases STAT3 signaling, suggesting that correct-localized emerin, by assembling with BAF and lamin A/C, acts as an intrinsic inhibitor against STAT3 signaling. In C2C12 cells, emerin knockdown induces STAT3 target gene, Pax7, and activated abnormal myoblast proliferation associated with muscle wasting in skeletal muscle homeostasis. Our results indicate that emerin downregulates STAT3 signaling by inducing retention of STAT3 and delaying STAT3 signaling in the nuclear membrane. This mechanism provides clues to the etiology of emerin-related muscular dystrophy and may be a new therapeutic target for treatment.

Colony-stimulating factor 3 signaling in colon and rectal cancers: Immune response and CMS classification in TCGA data

Colorectal cancer is the 2nd leading cause of cancer-related deaths in the world. The mechanisms underlying CRC development, progression, and resistance to treatment are complex and not fully understood. The immune response in the tumor microenvironment has been shown to play a significant role in many cancers, including colorectal cancer. Colony-stimulating factor 3 (CSF3) has been associated with changes to the immune environment in colorectal cancer animal models. We hypothesized that CSF3 signaling would correlate with pro-tumor tumor microenvironment changes associated with immune infiltrate and response. We utilized publicly available datasets to guide future mechanistic studies of the role CSF3 and its receptor (CSF3R) play in colorectal cancer development and progression. Here, we use bioinformatics data and mRNA from patients with colon (n = 242) or rectal (n = 92) cancers, obtained from The Cancer Genome Atlas Firehose Legacy dataset. We examined correlations of CSF3 and CSF3R expression with patient demographics, tumor stage and consensus molecular subtype classification. Gene expression correlations, cell type enrichment, Estimation of STromal and Immune cells in MAlignant Tumor tissues using Expression data scores and Gene Ontology were used to analyze expression of receptor and ligand, tumor microenvironment infiltration of immune cells, and alterations in biological pathways. We found that CSF3 and CSF3R expression is highest in consensus molecular subtype 1 and consensus molecular subtype 4. Ligand and receptor expression are also correlated with changes in T cell and macrophage signatures. CSF3R significantly correlates with a large number of genes that are associated with poor colorectal cancer prognosis.

New insights into molecular pathways in colorectal cancer: Adiponectin, interleukin-6 and opioid signaling

Colorectal cancer (CRC) is one of the most common cause of death among neoplasms around the world. The environmental factors, like diet and obesity, are crucial in CRC pathogenesis by creating cancer-favorable microenvironment and hormonal changes. Adiponectin, the adipose tissue-specific hormone, is generally considered to negatively correlate with CRC development. The interleukin 6 (IL-6) is one of the most important pro-inflammatory cytokine connected with CRC, which is strongly inflammation-associated. The opioids are variable group substantially correlated with cancers - the endogenous opioids affect immune system and cell cycle including proliferation and cell death whereas exogenous opioids are leading clinically used analgesics in terminal cancer patients. In this review we discuss the involvement of adiponectin, IL-6 and opioids in CRC pathogenesis, their link with obesity, possible cross-talk and potential novel therapeutic approach in CRC treatment.

Phosphorylated transducer and activator of transcription-3 (pSTAT3) immunohistochemical expression in paired primary and metastatic colorectal cancer

BACKGROUND

Signal Transducer and Activator of Transcription-3 (STAT3) mediates cellular functions. We assessed the IHC expression of phosphorylated STAT3 (pSTAT3) in paired primary tumors and liver metastases in patients with advanced stage colorectal cancer (CRC).

METHODS

We included patients with tissue blocks available from both the primary CRC and a surgically resected liver metastasis. The IHC pSTAT3 expression agreement was measured using Cohen's kappa statistic.

RESULTS

The study included 103 patients, 55% male, median age was 64. 43% tumors originated in rectum, and 63% of the primary tumors were synchronous. Expression of pSTAT3 was 76% in liver metastases and 71% in primary tumors. A difference in pSTAT3 staining between the primary tumor and liver metastases was noted in 64%. There was lost expression of pSTAT3 in the liver metastases in 28% and gained expression in 36% of cases compared to the primary. The kappa statistic comparing agreement between staining patterns of the primary tumors and liver metastases was a "less-than-chance", at -0.02. Median survival was 4.9 years, with no difference in survival outcomes by pSTAT3 expression in the primary tumor or liver metastases.

DISCUSSION

STAT3 is not a prognostic marker in the selective setting of metastatic CRC to liver, but it may remain a potential therapeutic target given most liver metastases expressed pSTAT3. Discordant pSTAT3 expression in between primary tumors and paired liver metastases suggests that use of this class of drug to treat liver predominant metastatic colorectal cancer in a biomarker-driven approach may require confirmatory liver tumor biopsy.

Novel Proteome Extraction Method Illustrates a Conserved Immunological Signature of MSI-H Colorectal Tumors

Using a simple, environment friendly proteome extraction (TOP), we were able to optimize the analysis of clinical samples. Using our TOP method we analyzed a clinical cohort of microsatellite stable (MSS) and unstable (MSI-H) colorectal carcinoma (CRC). We identified a tumor cell specific, STAT1-centered, immune signature expressed by the MSI-H tumor cells. We then showed that long, but not short, exposure to Interferon-γ induces a similar signature in vitro We identified 10 different temporal protein expression patterns, classifying the Interferon-γ protein temporal regulation in CRC. Our data sheds light on the changes that tumor cells undergo under long-term immunological pressure in vivo, the importance of STAT proteins in specific biological scenarios. The data generated could help find novel clinical biomarkers and therapeutic approaches.

p53-Regulated Long Noncoding RNA PRECSIT Promotes Progression of Cutaneous Squamous Cell Carcinoma via STAT3 Signaling

Long noncoding RNAs (lncRNAs) have emerged as putative biomarkers and therapeutic targets in cancer. The role of lncRNA LINC00346 in cutaneous squamous carcinoma (cSCC) was examined. The expression of LINC00346 was up-regulated in cSCC cells compared with normal human epidermal keratinocytes. Elevated expression of LINC00346 was noted in tumor cells in cSCC tissue sections in vivo, as compared with cSCC in situ, and actinic keratosis by RNA in situ hybridization; and the expression in seborrheic keratosis and normal skin was very low. Immunohistochemical analysis of cSCC tissue sections and functional assays of cSCC cells in culture showed that LINC00346 expression is down-regulated by p53. Knockdown of LINC00346 inhibited invasion of cSCC cells in culture and suppressed growth of human cSCC xenografts in vivo. Knockdown of LINC00346 inhibited expression of activated STAT3 and resulted in down-regulation of the expression of matrix metalloproteinase (MMP)-1, MMP-3, MMP-10, and MMP-13. Based on these observations LINC00346 was named p53 regulated carcinoma-associated STAT3-activating long intergenic non-protein coding transcript (PRECSIT). These results identify PRECSIT as a new p53-regulated lncRNA, which promotes progression of cSCC via STAT3 signaling.

Natural Sesquiterpene Lactones Enhance Chemosensitivity of Tumor Cells through Redox Regulation of STAT3 Signaling

STAT3 is a nuclear transcription factor that regulates genes involved in cell cycle, cell survival, and immune response. Although STAT3 activation drives cells to physiological response, its deregulation is often associated with the development and progression of many solid and hematological tumors as well as with drug resistance. STAT3 is a redox-sensitive protein, and its activation state is related to intracellular GSH levels. Under oxidative conditions, STAT3 activity is regulated by S-glutathionylation, a reversible posttranslational modification of cysteine residues. Compounds able to suppress STAT3 activation and, on the other hand, to modulate intracellular redox homeostasis may potentially improve cancer treatment outcome. Nowadays, about 35% of commercial drugs are natural compounds that derive from plant extracts used in phytotherapy and traditional medicine. Sesquiterpene lactones are an interesting chemical group of plant-derived compounds often employed in traditional medicine against inflammation and cancer. This review focuses on sesquiterpene lactones able to downmodulate STAT3 signaling leading to an antitumor effect and correlates the anti-STAT3 activity with their ability to decrease GSH levels in cancer cells. These properties make them lead compounds for the development of a new therapeutic strategy for cancer treatment.

STAT3 Regulates the Type I IFN-Mediated Antiviral Response by Interfering with the Nuclear Entry of STAT1

Signal transducer and activator of transcription 3 (STAT3) is a multifunctional factor that regulates inflammation and immunity. Knowledge of its regulatory mechanisms is very limited. Here, we showed that enterovirus 71 (EV71) infection induced the phosphorylation of STAT3 and the expression of its downstream inflammatory regulators. Knockdown of STAT3 with siRNAs significantly restricted viral RNA and protein levels, and also reduced viral titers. With further investigation, we found that importin α family member Karyopherin-α1 (KPNA1) was employed by both STAT1 and STAT3 for their nuclear import. The phosphorylated and un-phosphorylated STAT3 competed with STAT1 for binding to the decreased KPNA1 post infection and repressed downstream ISG expression. STAT3 knockdown alleviated the repressed type I IFN-mediated antiviral response upon infection and led to decreased viral replication. Taken together, our data suggested the role of STAT3 in maintaining the balance of inflammation and antiviral responses in the central nervous system (CNS) upon infection.

Natural product pectolinarigenin exhibits potent anti-metastatic activity in colorectal carcinoma cells in vitro and in vivo

Colorectal carcinoma (CRC) is one of the most common cancers with high metastatic potential, explaining why identifying new drug candidates that inhibit tumour metastasis is an urgent need. The aim of this study was to evaluate the biological activities of pectolinarigenin (PEC, a natural flavonoid present in Cirsium chanroenicum) in CRC in vitro and in vivo and to determine its underlying mechanism of action. Here, we observed that treatment with PEC could inhibit cell viability and induce apoptosis in cancer cells in a concentration- and time-dependent manner. The occurrence of apoptosis was associated with activation of caspase-3 and Bax and decreased expression of Bcl-2. In addition, PEC markedly impaired CRC cell migration and invasion by downregulating the expression of matrix metalloproteinase (MMP-9) and phosphorylated-Stat3^Tyr705. Moreover, our studies showed that PEC inhibited abdominal metastasis models of murine colorectal cancer. In addition, histological and immunohistochemical analyses revealed a decrease in Ki67-positive cells, MMP9-positive cells and p-Stat3^Tyr705 cells upon treatment with PEC compared to control samples. Furthermore, PEC reduced the number of myeloid-derived suppressor cells (MDSCs) in the blood and tumours, which was accompanied by the increased infiltration of CD8⁺T cells in the blood. Taken together, our findings suggested that PEC could be used as a natural drug to inhibit CRC metastasis.

Evaluation of the STAT3 inhibitor GLG‑302 for the prevention of estrogen receptor‑positive and ‑negative mammary cancers

Signal transducer and activator of transcription 3 (STAT3) plays a key role in the transformation of normal cells to cancerous cells. Although inhibitors of STAT3 have been shown to suppress the growth of multiple cancer types in vitro and in vivo, such agents are of particular interest for the prevention of breast cancer, which affects over 200,000 women and claims more than 40,000 lives in the United States each year. In the present study, we employed the MMTV/Neu transgenic mouse model, which develops estrogen receptor (ER)‑negative, Neu‑overexpressing tumors, and the Sprague‑Dawley (SD) rat model, which develops ER‑positive tumors upon exposure to the carcinogen 7,12‑dimethylbenz[a]anthracene (DMBA), to test the efficacy of the STAT3 inhibitor GLG‑302 in the prevention of mammary cancer. Orally administered GLG‑302 and its trizma salt derivative reduced mammary cancer incidence, multiplicity, and tumor weights in female MMTV/Neu mice, and GLG‑302 reduced tumor multiplicity and weights in female DMBA‑treated rats. Consistent with the mechanism of action of STAT3 inhibitors, the reductions in mammary tumors were correlated with decreases in STAT3 phosphorylation and cell proliferation. These data suggest that GLG‑302 is a novel agent with potential for prevention of mammary cancer and support the further development of STAT3 inhibitors for this cause.

Control of Tyrosine Kinase Signalling by Small Adaptors in Colorectal Cancer

Tyrosine kinases (TKs) phosphorylate proteins on tyrosine residues as an intracellular signalling mechanism to coordinate intestinal epithelial cell communication and fate decision. Deregulation of their activity is ultimately connected with carcinogenesis. In colorectal cancer (CRC), it is still unclear how aberrant TK activities contribute to tumour formation because TK-encoding genes are not frequently mutated in this cancer. In vertebrates, several TKs are under the control of small adaptor proteins with potential important physiopathological roles. For instance, they can exert tumour suppressor functions in human cancer by targeting several components of the oncogenic TK signalling cascades. Here, we review how the Src-like adaptor protein (SLAP) and the suppressor of cytokine signalling (SOCS) adaptor proteins regulate the SRC and the Janus kinase (JAK) oncogenic pathways, respectively, and how their loss of function in the intestinal epithelium may influence tumour formation. We also discuss the potential therapeutic value of these adaptors in CRC.

Plasmodium infection inhibits the expansion and activation of MDSCs and Tregs in the tumor microenvironment in a murine Lewis lung cancer model

BACKGROUND

A major challenge in the development of effective cancer immunotherapy is the ability of tumors and their microenvironment to suppress immune cells through immunosuppressive cells such as myeloid -derived suppressor cells and regulatory T cells. We previously demonstrated that Plasmodium infection promotes innate and adaptive immunity against cancer in a murine Lewis lung cancer model but its effects on immunosuppressive cells in the tumor microenvironment are unknown.

METHODS

Whole Tumors and tumor-derived sorted cells from tumor-bearing mice treated with or without plasmodium infected red blood cells were harvested 17 days post tumor implantation and analyzed using QPCR, western blotting, flow cytometry, and functional assays. Differences between groups were analyzed for statistical significance using Student's t-test.

RESULTS

Here we found that Plasmodium infection significantly reduced the proportions of MDSCs and Tregs in the lung tumor tissues of the treated mice by downregulating their recruiting molecules and blocking cellular activation pathways. Importantly, CD8⁺ T cells isolated from the tumors of Plasmodium-treated mice exhibited significantly higher levels of granzyme B and perforin and remarkably lower levels of PD-1.

CONCLUSION

We reveal for the first time, the effects of Plasmodium infection on the expansion and activation of MDSCs and Tregs with a consequent elevation of CD8⁺T cell-mediated cytotoxicity within the tumor microenvironment and hold great promise for the development of effective immunotherapeutic strategies.

Tumor cell density regulates matrix metalloproteinases for enhanced migration

Matrix metalloproteinases (MMPs) may play a critical role in metastatic cancers, yet multiple human clinical trials targeting MMPs have surprisingly failed. Cancer cell density changes dramatically during the early growth of a primary tumor and during the early seeding steps of secondary tumors and has been implicated in playing an important role in regulating metastasis and drug resistance. This study reveals that the expression of MMPs is tightly regulated by local tumor cell density through the synergistic signaling mechanism of Interleukin 6 (IL-6) and Interleukin 8 (IL-8) via the JAK2/STAT3 complex. Local tumor cell density also plays a role in the responsiveness of cells to matrix metalloproteinases inhibitors (MMPI), such as Batimastat, Marimastat, Bryostatin I, and Cipemastat, where different migratory phenotypes are observed in low and high cell density conditions. Cell density-dependent MMP regulation can be directly targeted by the simultaneous inhibition of IL-6 and IL-8 receptors via Tocilizumab and Reparixin to significantly decrease the expression of MMPs in mouse xenograft models and decrease effective metastasis. This study reveals a new strategy to decrease MMP expression through pharmacological intervention of the cognate receptors of IL-6 and IL-8 to decrease metastatic capacity of tumor cells.

The relationship between lncRNA PCGEM1 and STAT3 during the occurrence and development of endometrial carcinoma

We investigated the effects of lncRNA PCGEM1 on the tumorigenesis and development of endometrial carcinoma (EC) and its possible molecular mechanism. We found that PCGEM1 expression was significantly higher in EC tissues than in normal endometrial tissues via quantitative reverse transcription (qRT)-PCR. The upregulation of PCGEM1 promoted the proliferation, migration, and invasive ability of EC cells while inhibiting apoptosis. The silencing of PCGEM1 had the opposite effects. Nude mouse xenograft assay showed that PCGEM1 overexpression could promote tumor growth in vivo. Western blotting and immunohistochemistry showed that PCGEM1 also upregulated STAT3 expression, which affected the expression of B-cell lymphoma-2, survivin, vascular endothelial growth factor A, and matrix metalloproteinase-2. Furthermore, the dual-luciferase reporter assay confirmed that miR-129-5p could bind directly to both PCGEM1 and STAT3. In addition, qRT-PCR showed that overexpression of PCGEM1 caused a decrease in miR-129-5p expression, and silencing of PCGEM1 produced the opposite result. In the PCGEM1-overexpressing cells, overexpression of miR-129-5p reduced the expression of STAT3 at both mRNA and protein levels. Thus, we confirmed that PCGEM1 could upregulate the expression of STAT3 by acting as a competing endogenous RNA for miR-129-5p, thereby affecting the occurrence and development of EC.

IL-12-mediated transcriptional regulation of matrix metalloproteinases

Matrix metalloproteinases (MMPs) are extracellular matrix (ECM) remodelling enzymes involved in developmental processes, tissue remodelling and repair, inflammatory and immune diseases and cancer. In a recent issue of Bioscience Reports (vol. 37, issue 6, BSR20170973), Liu and colleagues investigated the expression of MMPs such as MMP-1 (interstitial collagenase), MMP-3 (stromelysin 1) and MMP-13 (collagenase 3) in human periodontal ligament fibroblasts (hPDLFs) regulated by interleukin-12 (IL-12), a cytokine implicated in inflammatory and immune responses. They showed that IL-12 activates canonical nuclear factor-κB (NF-κB) signalling leading to increased expression of MMP-1, MMP-3 and MMP-13, and to a smaller reduction in the expression of MMP-2 (gelatinase A) and MMP-9 (gelatinase B) at both mRNA and protein levels, with corresponding changes in the secreted levels of these ECM-remodelling and immune regulatory metalloproteinases. While canonical NF-κB signalling regulates these MMPs, it also interacts with additional factors to determine whether some of these MMPs are induced or downregulated, in response to IL-12. Here, we comment on the possible mechanisms of IL-12-mediated transcriptional regulation of MMPs.

Carcinoma-associated fibroblasts affect sensitivity to oxaliplatin and 5FU in colorectal cancer cells

The importance of tumor microenvironment (TME) as a relevant contributor to cancer progression and its role in the development of de novo resistance to targeted therapies has become increasingly apparent. However, the mechanisms of microenvironment-mediated drug resistance for nonspecific conventional chemotherapeutic agents, such as platinum compounds or antimetabolites, are still unclear.

Here we describe a mechanism induced by soluble factors released by carcinoma-associated fibroblasts (CAFs) that induce the translocation of AKT, Survivin and P38 to the nucleus of tumor cells. These changes are guided to ensure DNA repair and the correct entrance and exit from mitosis in the presence of chemotherapy. We used conditioned media (CM) from normal-colonic fibroblasts and paired CAFs to assess dose response curves of oxaliplatin and 5-fluorouracil, separately or combined, compared with standard culture medium. We also evaluated a colony-forming assay and cell death to demonstrate the protective role of CAF-CM. Immunofluorescence confirmed the translocation of AKT, P38 and Survivin to the nucleus induced by CAF-soluble factors. We also have shown that STAT3 or P38 inhibition provides a promising strategy for overcoming microenvironment-mediated resistance. Conversely, pharmacologic AKT inhibition induces an antagonistic effect that relieves a cMET and STAT3-mediated compensatory feedback that might explain the failure of AKT inhibitors in the clinic so far.

The ratio of STAT1 to STAT3 expression is a determinant of colorectal cancer growth

The role of STAT1 and STAT3 for colorectal carcinoma (CRC) development and progression is controversial. We evaluated 414 CRC patient samples on tissue microarrays for differential expression of STAT1 and STAT3 protein levels and correlated ratios with clinical parameters. Concomitant absence of nuclear STAT1 and STAT3 expression was associated with significantly reduced median survival by ≥33 months (p=0.003). To gain insight into underlying mechanisms, we generated four CRC cell lines with STAT3 knockdown. The cell lines harbor different known mutational drivers and were xenografted into SCID mice to analyze the influence of STAT3 on their tumor growth behavior. Experimental downregulation of STAT3 expression had differential, cell-line specific effects on STAT1 expression levels. STAT1 consistently showed nuclear localization irrespective of its tyrosine phosphorylation status. Two characteristic STAT1/3 expression patterns with opposite growth behavior could be distinguished: cell lines with a low STAT1/high STAT3 ratio showed faster tumor growth in xenografts. In contrast, xenografts of cell lines showing high STAT1 and low STAT3 levels grew slower. Importantly, these ratios reflected clinical outcome in CRC patients as well. We conclude that the ratio of STAT1 to STAT3 expression is a key determinant of CRC progression and that STAT1 counteracts pro-tumorigenic STAT3 signaling. Thus, we suggest that the STAT3/STAT1 ratios are better clinical predictors in CRC as compared to STAT3 or STAT1 levels alone.

Whitening and anti-wrinkle activities of ferulic acid isolated from Tetragonia tetragonioides in B16F10 melanoma and CCD-986sk fibroblast cells

Ferulic acid isolated from Tetragonia tetragonioides was tested for its whitening effect on the B16F10 mouse melanoma cell line and its anti-wrinkle activity on the CCD-986sk human dermal fibroblast cell line. Ferulic acid, one of the primary phenolic compounds that can be isolated from T. tetragonioides, has been reported to show potential as a functional food, for its whitening effect and anti-wrinkle activity. To measure its whitening and anti-wrinkle activities, cells were treated with ferulic acid isolated from T. tetragonioides at concentrations between 5 and 20 μM. Ferulic acid showed no cytotoxicity at concentrations up to 20 μM. Ferulic acid inhibited melanin synthesis, tyrosinase expression, and microphthalmia transcription factor expression in B16F10 cells stimulated with α-melanocyte stimulating hormone. Ferulic acid induced procollagen synthesis, hyaluronic acid synthesis, tissue inhibitor of metalloproteinase synthesis, and inhibited matrix metalloproteinase (MMP)-1 and MMP-9 expression in CCD-986sk cells stimulated with UV-B. On the basis of these results, we conclude that ferulic acid isolated from T. tetragonioides shows potential for use as a functional food, with whitening and anti-wrinkle activities.

Stress responsive miR-31 is a major modulator of mouse intestinal stem cells during regeneration and tumorigenesis

Intestinal regeneration and tumorigenesis are believed to be driven by intestinal stem cells (ISCs). Elucidating mechanisms underlying ISC activation during regeneration and tumorigenesis can help uncover the underlying principles of intestinal homeostasis and disease including colorectal cancer. Here we show that miR-31 drives ISC proliferation, and protects ISCs against apoptosis, both during homeostasis and regeneration in response to ionizing radiation injury. Furthermore, miR-31 has oncogenic properties, promoting intestinal tumorigenesis. Mechanistically, miR-31 acts to balance input from Wnt, BMP, TGFβ signals to coordinate control of intestinal homeostasis, regeneration and tumorigenesis. We further find that miR-31 is regulated by the STAT3 signaling pathway in response to radiation injury. These findings identify miR-31 as a critical modulator of ISC biology, and a potential therapeutic target for a broad range of intestinal regenerative disorders and cancers.

Cells lining the inner wall of the gut help to absorb nutrients and to protect the body against harmful microbes and substances. Being on the front line of defense means that these cells often sustain injuries. Specialized cells called intestinal stem cells keep the tissues healthy by replacing the damaged and dying cells.

The intestinal stem cells can produce copies of themselves and generate precursors of the gut cells. They also have specific mechanism to protect themselves from cell death. These processes are regulated by different signals that are generated by the cell themselves or the neighboring cells. If these processes get out of control, cells can easily be depleted or develop into cancer cells. Until now, it remained unclear how intestinal stem cells can differentiate between and respond to multiple and simultaneous signals.

It is known that short RNA molecules called microRNA play an important role in the signaling pathways of damaged cells and during cancer development. In the gut, different microRNAs, including microRNA-31,help to keep the gut lining intact. However, previous research has shown that bowel cancer cells also contain high amounts of microRNA-31.

To see whether microRNA-31 plays a role in controlling the signaling systems in intestinal stem cells, Tian, Ma, Lv et al. looked at genetically modified mice that either had too much microRNA-31 or none. Mice with too much microRNA-31 produced more intestinal stem cells and were able to better repair any cell damage. Mice without microRNA-31 gave rise to fewer intestinal stem cellsand had no damage repair, but were able to stop cancer cells in the gut from growing.

The results showed that microRNA-31 in intestinal stem cells helps the cells to divide and to protect themselves from cell death. It controlled and balanced the different types of cell signaling by either repressing or activating various signals. When Tian et al. damaged the stem cells using radiation, the cells increased their microRNA-31 levels as a defense mechanism. This helped the cells to survive and to activate repair mechanisms. Furthermore, Tian et al. discovered that microRNA-31 can enhance the growth of tumors.

These results indicate that microRNA-31 plays an important role both in repairing gut linings and furthering tumor development. A next step will be to see whether cancer cells use microRNA-31 to protect themselves from chemo- and radiation therapy. This could help scientists find new ways to render cancerous cells more susceptible to existing cancer therapies.

Novel STAT binding elements mediate IL-6 regulation of MMP-1 and MMP-3

Dynamic remodelling of the extracellular matrix (ECM) is a key feature of cancer progression. Enzymes that modify the ECM, such as matrix metalloproteinases (MMPs), have long been recognised as important targets of anticancer therapy. Inflammatory cytokines are known to play a key role in regulating protease expression in cancer. Here we describe the identification of gamma-activated site (GAS)-like, signal transducer and activator of transcription (STAT) binding elements (SBEs) within the proximal promoters of the MMP-1 and MMP-3 genes, which in association with AP-1 components (c-Fos or Jun), bind STAT-1 in a homodimer like complex (HDLC). We further demonstrate that MMP expression and binding of this complex to SBEs can either be enhanced by interleukin (IL)-6, or reduced by interferon gamma (IFN-γ), and that IL-6 regulation of MMPs is not STAT-3 dependent. Collectively, this data adds to existing understanding of the mechanism underlying cytokine regulation of MMP expression via STAT-1, and increases our understanding of the links between inflammation and malignancy in colon cancer.

Mechanisms of CXCR7 induction in malignant melanoma development

Malignant melanoma (MM) is a highly malignant skin tumor. The mechanism of MM pathogenesis and its signaling pathways are not well characterized. C-X-C chemokine receptor type 7 (CXCR7) has been reported to regulate cancer cell invasion. The present study sought to investigate the effects of CXCR7 on MM development. First, CXCR7 expression levels were assessed in the skin tumor tissue of patients with MM. Then, CXCR7 small hairpin RNA was used in M14 melanoma cells in a Transwell culture model and in a transplanted mouse model to test the effects of CXCR7. In addition, immunohistochemistry staining, reverse transcription-quantitative polymerase chain reaction and western blotting were used. The results revealed that CXCR7 expression levels were significantly higher in MM tissue compared with squamous cell carcinoma or basal cell carcinoma tissue. Knocking down CXCR7 in M14 cells significantly inhibited cell migration and invasion in the Transwell culture model. Furthermore, CXCR7 knockdown also significantly reduced the transplanted tumor size, weight and vascular number in the mouse model. It was concluded that CXCR7 interacts with C-X-C motif chemokine ligand 12 to activate the chemokine receptor signaling pathway, and to increase melanoma cell migration, invasion and development.

18 β-glycyrrhetinic acid exhibits potent antitumor effects against colorectal cancer via inhibition of cell proliferation and migration

Accumulating evidence shows that 18 β-glycyr-rhetinic acid (GRA) has antitumor activities in breast, ovarian cancer and leukemia, while its role in colorectal cancer remains unknown. In the present study, we investigated the effect of GRA in colorectal cancer cells LoVo, SW480 and SW620 and studied the underlying molecular mechanisms. Results showed that GRA had potent inhibitory effects on colorectal cancer cell proliferation in a dose- and time-dependent manner in vitro and in vivo. Growth inhibition was mediated by pro-apoptosis, as evident from Annexin V-FITC staining, the reduced expression of survivin and the induced expression of cleaved PARP. Furthermore, GRA treatment resulted in marked reduction of cell migration, invasion and wound healing capability, accompanying by the downregulated MMP expression. Moreover, GRA decreased the protein levels of p-PI3K, p-AKT, p-STAT3, p-JNK, p-p38 and p-NF-κB p65, of which the phosphorylation of PI3K and STAT3 decreased as early as 2 h after the GRA treatment. These results suggest that regulation of the apoptosis, invasion and migration of colorectal cancer cells by GRA might be through suppressing PI3K and STAT3 signaling pathways. the present study indicated that GRA could be a potential effective therapy for patients with colorectal cancer.

27-Hydroxycholesterol induces invasion and migration of breast cancer cells by increasing MMP9 and generating EMT through activation of STAT-3

Breast carcinoma plays a vital role in the reasons of global women's death. ER-related invasion and migration play an important part in the development and prognosis of breast cancer. Here, we found that 27-Hydroxycholesterol (27HC) could induce epithelial-mesenchymal transition (EMT) and increase the expression of the matrix metalloproteinase 9 (MMP9) at mRNA level and the active form. Meanwhile, interestingly, we found 27HC activated signal transducer and activator of transcription 3 (STAT-3) in ER positive cells except activation of ER signaling. Furthermore, inhibition of STAT-3 by siRNA attenuated the 27HC-induced improvement of MMP9 and decreased the invasion and migration ability in MCF7 and T47D cells. In addition, 27HC could also promote MMP9, vimentin and active STAT-3 in the ER negative cells MDA-MB-231. All these results not only raise a mechanism whereby 27HC enhances the invasion and metastasis, but also is helpful to realize 27HC as a potential endogenous detrimental factor in breast tumor patients.

Steering of carcinoma progression by the YIN/YANG interaction of STAT1/STAT3

STAT1/STAT3 transcription factors are important regulators for development of normal, infected or inflammed cells. They are also critically involved in the progression of various malignant tumours, including epithelial-derived carcinomas. Here, we focus on colorectal cancer (CRC) insights for STAT1/3, where controversial functions for STAT3 were reported. For a long time STAT3 has been regarded as a driver of tumour malignancy and its activation was associated with negative clinical outcome. In contrast, STAT1 was generally viewed as an independent tumour suppressor and positive prognostic marker. Here we discuss the experimental evidence for the tight association and regulation of oncogenic STAT3 transcription kept at bay by nuclear STAT1. We summarise current research and describe cellular models of different STAT1/STAT3 expression ratios. STAT1/3 expression levels are influenced by the mutational status of carcinoma cells associated with nuclear unphosphorylated STAT1. Animal tumour models and results from in vitro experiments allow for the conclusion that both proteins interact as antagonistic transcription factors in CRC cells. These STATs steer also important processes during infection and inflammation that influence development and progression of CRC. The STAT1/3 interplay is important to understand gene regulation and we describe it here similar like the YIN/YANG dualism. Thus, we propose to evaluate both STAT1 and STAT3 expression patterns in cancers in a dual manner instead of regarding them as independent transcription factors. This conceptual dualistic view could advance diagnostic predictions in the future.

Regulation of EMT by STAT3 in gastrointestinal cancer (Review)

Gastrointestinal (GI) cancer is characterized by its aggressiveness and tendency to metastasize at early stage. Epithelial-mesenchymal transition (EMT), commonly known as the preparing step of metastasis, may account for the aggressive phenotype of GI cancer cells. The process of EMT is finely orchestrated by multiple layers of regulators. Signal transducer and activator of transcription 3 (STAT3) is a transcription factor constitutively activated in diverse malignancies. Recent studies have suggested an involvement of STAT3 in GI cancer EMT. In this review, we first take an insight into the oncogenic functions of STAT3 in GI cancer, and then summarize the possible mechanisms by which STAT3 regulates the EMT process. Through the extensive interactions with EMT-inducing transcription factors and non-coding RNAs, and crosstalk with other signaling pathways, STAT3 has been demonstrated to promote the mesenchymal and invasive phenotype of GI cancer, which provides rationales for specifically targeting STAT3 to prevent and reverse the progression of GI cancer.

β-Asarone inhibits gastric cancer cell proliferation

β-Asarone is the main volatile oil of Chinese herb Rhizoma Acori Tatarinowii. It exhibits a wide range of biological activities in many human organs. However, few studies have investigated the effect of β-asarone on gastric cancer. The present study investigated the effect of β-asarone on the proliferation and apoptosis of three types of differentiated human gastric cancer cell lines (SGC-7901, BGC-823 and MKN-28) in vitro as well as the related molecular mechanisms. Methyl thiazolyl tetrazolium assay, Annexin V/PI double staining, immunofluorescence test and transmission electron microscopy all confirmed that β-asarone had an obvious dose-dependent inhibitive effect on the proliferation of human gastric cancer cells and induced apoptosis of the cell lines. Transwell invasion, wound-healing and matrix‑cell adhesion experiments confirmed that β-asarone inhibited the invasion, migration and adhesion of human gastric cancer BGC-823 cells. Quantitative real-time PCR and western blotting found that β-asarone significantly activated caspase-3, caspase-8, caspase-9, Bax, Bak and suppressed Bcl-2, Bcl-xL and survivin activity. Moreover, β-asarone increased the expression of RECK, E-cadherin and decreased the expression of MMP-2, MMP-9, MMP-14 and N-cadherin. The present study demonstrated that β-asarone effectively inhibits the proliferation of human gastric cancer cells, induces their apoptosis and decreased the invasive, migratory and adhesive abilities.

FAD104, a Regulator of Adipogenesis and Osteogenesis, Interacts with the C-Terminal Region of STAT3 and Represses Malignant Transformation of Melanoma Cells

Anchorage-independent growth is one of the defining characteristics of cancer cells. Many oncogenes and tumor suppressor genes are involved in regulating this type of growth. Factor for adipocyte differentiation 104 gene (fad104) is a regulator of adipogenesis and osteogenesis. Previously, we reported that fad104 suppressed metastasis as well as invasion of melanoma cells. However, it is unclear whether fad104 is involved in malignant transformation, which is associated with metastasis. In this study, we revealed that fad104 negatively regulated the colony forming activity of melanoma cells. The presence of the N-terminal region of FAD104 was required for the regulation of malignant transformation of melanoma cells. In addition, the deletion mutant of FAD104 that contained the N-terminal region and transmembrane domain interacted with signal transducer and activator of transcription 3 (STAT3) and suppressed STAT3 activity. However, the deletion mutant of FAD104 lacking the N-terminal region did not influence the interaction with STAT3 or suppress the STAT3 activity. Moreover, FAD104 interacted with the C-terminal region of STAT3. In summary, we demonstrated that fad104 suppressed anchorage-independent growth of melanoma cells, and that the N-terminal region of FAD104 is essential for inhibiting malignant transformation and STAT3 activity.

Hes1 Increases the Invasion Ability of Colorectal Cancer Cells via the STAT3-MMP14 Pathway

The Notch pathway contributes to self-renewal of tumor-initiating cell and inhibition of normal colonic epithelial cell differentiation. Deregulated expression of Notch1 and Jagged1 is observed in colorectal cancer. Hairy/enhancer of split (HES) family, the most characterized targets of Notch, involved in the development of many cancers. In this study, we explored the role of Hes1 in the tumorigenesis of colorectal cancer. Knocking down Hes1 induced CRC cell senescence and decreased the invasion ability, whereas over-expression of Hes1 increased STAT3 phosphorylation activity and up-regulated MMP14 protein level. We further explored the expression of Hes1 in human colorectal cancer and found high Hes1 mRNA expression is associated with poor prognosis in CRC patients. These findings suggest that Hes1 regulates the invasion ability through the STAT3-MMP14 pathway in CRC cells and high Hes1 expression is a predictor of poor prognosis of CRC.

Diphlorethohydroxycarmalol Suppresses Ultraviolet B-Induced Matrix Metalloproteinases via Inhibition of JNK and ERK Signaling in Human Keratinocytes

Skin aging is the most readily observable process involved in human aging. Ultraviolet B (UVB) radiation causes photo-oxidation via generation of reactive oxygen species (ROS), thereby damaging the nucleus and cytoplasm of skin cells and ultimately leading to cell death. Recent studies have shown that high levels of solar UVB irradiation induce the synthesis of matrix metalloproteinases (MMPs) in skin fibroblasts, causing photo-aging and tumor progression. The MMP family is involved in the breakdown of extracellular matrix in normal physiological processes such as embryonic development, reproduction, and tissue remodeling, as well as in disease processes such as arthritis and metastasis. We investigated the effect of diphlorethohydroxycarmalol (DPHC) against damage induced by UVB radiation in human skin keratinocytes. In UVB-irradiated cells, DPHC significantly reduced expression of MMP mRNA and protein, as well as activation of MMPs. Furthermore, DPHC reduced phosphorylation of ERK and JNK, which act upstream of c-Fos and c-Jun, respectively; consequently, DPHC inhibited the expression of c-Fos and c-Jun, which are key components of activator protein-1 (AP-1, up-regulator of MMPs). Additionally, DPHC abolished the DNA-binding activity of AP-1, and thereby prevented AP-1-mediated transcriptional activation. These data demonstrate that by inactivating ERK and JNK, DPHC inhibits induction of MMPs triggered by UVB radiation.

Alterations in microRNAs miR-21 and let-7a correlate with aberrant STAT3 signaling and downstream effects during cervical carcinogenesis

BACKGROUND

Present study provides clinical evidence of existence of a functional loop involving miR-21 and let-7a as potential regulators of aberrant STAT3 signaling recently reported by our group in an experimental setup (Shishodia et al. BMC Cancer 2014, 14:996). The study is now extended to a set of cervical tissues that represent natural history of human papillomavirus (HPV)-induced tumorigenic transformation.

MATERIALS AND METHODS

Cervical tissues from histopathologically-confirmed pre-cancer (23) and cancer lesions (56) along with the normal control tissues (23) were examined for their HPV infection status, expression level of miR-21 & let-7a and STAT3 & pSTAT3 (Y705) by PCR-based genotyping, quantitative real-time PCR and immunoblotting.

RESULTS

Analysis of cancer tissues revealed an elevated miR-21 and reduced let-7a expression that correspond to the level of STAT3 signaling. While miR-21 showed direct association, let-7a expression was inversely related to STAT3 expression and its activation. In contrast, a similar reciprocal expression kinetics was absent in LSIL and HSIL tissues which overexpressed let-7a. miR-21 was found differentially overexpressed in HPV16-positive lesions with a higher oncoprotein E6 level. Overexpression of miR-21 was accompanied by elevated level of other STAT3-regulated gene products MMP-2 and MMP-9. Enhanced miR-21 was found associated with decreased level of STAT3 negative regulator PTEN and negative regulator of MMPs, TIMP-3.

CONCLUSION

Overall, our study suggests that the microRNAs, miR-21 and let-7a function as clinically relevant integral components of STAT3 signaling and are responsible for maintaining activated state of STAT3 in HPV-infected cells during cervical carcinogenesis.

Lung Adenocarcinomas and Lung Cancer Cell Lines Show Association of MMP-1 Expression With STAT3 Activation

Signal transducer and activator of transcription 3 (STAT3) is constitutively activated in the majority of lung cancer. This study aims at defining connections between STAT3 function and the malignant properties of non–small cell lung carcinoma (NSCLC) cells. To address possible mechanisms by which STAT3 influences invasiveness, the expression of matrix metalloproteinase-1 (MMP-1) was analyzed and correlated with the STAT3 activity status. Studies on both surgical biopsies and on lung cancer cell lines revealed a coincidence of STAT3 activation and strong expression of MMP-1. MMP-1 and tyrosine-phosphorylated activated STAT3 were found co-localized in cancer tissues, most pronounced in tumor fronts, and in particular in adenocarcinomas. STAT3 activity was constitutive, although to different degrees, in the lung cancer cell lines investigated. Three cell lines (BEN, KNS62, and A549) were identified in which STAT3 activitation was inducible by Interleukin-6 (IL-6). In A549 cells, STAT3 activity enhanced the level of MMP-1 mRNA and stimulated transcription from the MMP-1 promoter in IL-6–stimulated A549 cells. STAT3 specificity of this effect was confirmed by STAT3 knockdown through RNA interference. Our results link aberrant activity of STAT3 in lung cancer cells to malignant tumor progression through up-regulation of expression of invasiveness-associated MMPs.

Malignancy of bladder cancer cells is enhanced by tumor-associated fibroblasts through a multifaceted cytokine-chemokine loop

The microenvironment of tumor cells is critically involved in tumor development and progression. Tumor-associated fibroblasts (TAFs) represent a major constituent of the tumor stroma. Tumor cells are operative in the activation of TAFs, whereas TAFs in turn contribute to tumor cell malignancy. This report describes mechanisms of communication between fibroblasts and urinary bladder cancer (UBC) cells. Migration of bladder cancer cell lines RT112 and Cal-29, representing two different grades of dedifferentiation, was enhanced by cocultivation with TAFs. Conditioned medium from tumor cells induced the release of interleukin (IL)-8, hepatocyte growth factor (HGF), matrix metalloproteinase-2, granulocyte macrophage colony-stimulating factor, and monocyte chemotactic protein (MCP)-1 by TAFs. Tumor cell-derived IL-1α was identified as a major mediator of these stimulatory effects. Fibroblasts, on the other hand, exerted a migration and invasion stimulating influence on UBC cells. MCP-1 and HGF were shown to promote cell migration of both bladder cancer cell lines.

Ubiquitin-specific peptidase 22 inhibits colon cancer cell invasion by suppressing the signal transducer and activator of transcription 3/matrix metalloproteinase 9 pathway

Colon cancer is associated with increased cell migration and invasion. In the present study, the role of ubiquitin-specific peptidase 22 (USP22) in signal transducer and activator of transcription 3 (STAT3)-mediated colon cancer cell invasion was investigated. The messenger RNA levels of STAT3 target genes were measured by reverse transcription-quantitative polymerase chain reaction, following USP22 knockdown by RNA interference in SW480 colon cancer cells. The matrix metalloproteinase 9 (MMP9) proteolytic activity and invasion potential of SW480 cells were measured by zymography and Transwell assay, respectively, following combined USP22 and STAT3 short interfering (si)RNA treatment or STAT3 siRNA treatment alone. Similarly, a cell counting kit-8 assay was used to detect the proliferation potential of SW480 cells. The protein expression levels of USP22, STAT3 and MMP9 were detected by immunohistochemistry in colon cancer tissue microarrays (TMAs) and the correlation between USP22, STAT3 and MMP9 was analyzed. USP22/STAT3 co-depletion partly rescued the MMP9 proteolytic activity and invasion of SW480 cells, compared with that of STAT3 depletion alone. However, the proliferation of USP22/STAT3si-SW480 cells was decreased compared with that of STAT3si-SW480 cells. USP22 expression was positively correlated with STAT3 and MMP9 expression in colon cancer TMAs. In conclusion, USP22 attenuated the invasion capacity of colon cancer cells by inhibiting the STAT3/MMP9 signaling pathway.

Expressional STAT3/STAT5 Ratio is an Independent Prognostic Marker in Colon Carcinoma

BACKGROUND

Signal transducer and activator of transcription proteins (STATs) are crucial regulators of cell growth and differentiation; however, their specific prognostic impact in human colon cancer has only been studied to limited extent. We aimed to assess the prognostic significance of specific STAT expression patterns in colon carcinoma.

METHODS

Protein expression patterns of activated STAT1, STAT3, STAT4, and STAT5 in human colon carcinoma tissue and corresponding healthy mucosa (n = 104) were assessed using multiplex bead-based immunoassay technologies. Expression patterns were correlated with clinical and survival data. Immunohistochemistry was performed to assess spatial expression of STAT3 and STAT5.

RESULTS

STAT3 was underexpressed whereas STAT4 and STAT5 were overexpressed in colon carcinoma tissue. Primary tumors from patients with distant metastases (M1) displayed significantly increased expression of STAT1 and STAT3 but decreased expression of STAT4 and STAT5. Increased tumor expression of STAT1 or STAT3 was associated with impaired patient survival, whereas increased expression of STAT4 or STAT5 correlated with improved survival. Multivariate analysis identified an increased STAT3/STAT5 expressional ratio as an adverse prognostic marker in colon cancer patients.

CONCLUSIONS

The tumor progression-associated transcription factors STAT3, STAT4, and STAT5 are differently expressed in colon carcinoma tissue and colon mucosa. Moreover, the STAT3/STAT5 expression ratio is an independent prognostic marker in colon cancer patients.

The role of hypoxia in inflammatory disease (review)

Mammals have developed evolutionarily conserved programs of transcriptional response to hypoxia and inflammation. These stimuli commonly occur together in vivo and there is significant crosstalk between the transcription factors that are classically understood to respond to either hypoxia or inflammation. This crosstalk can be used to modulate the overall response to environmental stress. Several common disease processes are characterised by aberrant transcriptional programs in response to environmental stress. In this review, we discuss the current understanding of the role of the hypoxia-responsive (hypoxia-inducible factor) and inflammatory (nuclear factor-κB) transcription factor families and their crosstalk in rheumatoid arthritis, inflammatory bowel disease and colorectal cancer, with relevance for future therapies for the management of these conditions.

SIAH2 antagonizes TYK2-STAT3 signaling in lung carcinoma cells

The Janus tyrosine kinases JAK1-3 and tyrosine kinase-2 (TYK2) are frequently hyperactivated in tumors. In lung cancers JAK1 and JAK2 induce oncogenic signaling through STAT3. A putative role of TYK2 in these tumors has not been reported. Here, we show a previously not recognized TYK2-STAT3 signaling node in lung cancer cells. We reveal that the E3 ubiquitin ligase seven-in-absentia-2 (SIAH2) accelerates the proteasomal degradation of TYK2. This mechanism consequently suppresses the activation of STAT3. In agreement with these data the analysis of primary non-small-cell lung cancer (NSCLC) samples from three patient cohorts revealed that compared to lung adenocarcinoma (ADC), lung squamous cell carcinoma (SCC) show significantly higher levels of SIAH2 and reduced STAT3 phosphorylation levels. Thus, SIAH2 is a novel molecular marker for SCC. We further demonstrate that an activation of the oncologically relevant transcription factor p53 in lung cancer cells induces SIAH2, depletes TYK2, and abrogates the tyrosine phosphorylation of STAT1 and STAT3. This mechanism appears to be different from the inhibition of phosphorylated JAKs through the suppressor of cytokine signaling (SOCS) proteins. Our study may help to identify molecular mechanisms affecting lung carcinogenesis and potential therapeutic targets.

PAC exhibits potent anti-colon cancer properties through targeting cyclin D1 and suppressing epithelial-to-mesenchymal transition

Colorectal cancer (CRC) is a major cause of cancer morbidity and mortality worldwide. Although response rates and overall survival have been improved in recent years, resistance to multiple drug combinations is inevitable. Therefore, the development of more efficient drugs, with fewer side effects is urgently needed. To this end, we have investigated in the present report the effect of PAC, a novel cucumin analogue, on CRC cells both in vitro and in vivo. We have shown that PAC induces apoptosis, mainly via the internal mitochondrial route, and inhibits cell proliferation through delaying the cell cycle at G2/M phase. Interestingly, the pro-apoptotic effect was mediated through STAT3-dependent down-regulation of cyclin D1 and its downstream target survivin. Indeed, change in the expression level of cyclin D1 modulated the expression of survivin and the response of CRC cells to PAC. Furthermore, using the ChIP assay, we have shown PAC-dependent reduction in the binding of STAT3 to the cyclin D1 promoter in vivo. Additionally, PAC suppressed the epithelial-to-mesenchymal process through down-regulating the mesenchymal markers (N-cadherin, vimentin and Twist1) and inhibiting the invasion/migration abilities of the CRC cells via repressing the pro-migration/invasion protein kinases AKT and ERK1/2. In addition, PAC inhibited tumor growth and repressed the JAK2/STAT3, AKT/mTOR and MEK/ERK pathways as well as their common downstream effectors cyclin D1 and survivin in humanized CRC xenografts. Collectively, these results indicate that PAC has potent anti-CRC effects, and therefore could constitute an effective alternative chemotherapeutic agent, which may consolidate the adjuvant treatment of colon cancer.

Anticancer effect of salidroside on colon cancer through inhibiting JAK2/STAT3 signaling pathway

Salidroside is considered to have anti-tumor properties. We investigate its effects on colon carcinoma SW1116 cells. Cell viability was assessed by CCK-8. Propidium iodide (PI) staining was used to determine the cell cycle by flow cytometry. The migration and invasion were detected by Transwell. Western blot was used to detect the expression of STAT3 signal related proteins. As the result, high concentrations of salidroside (10, 20. 50 μg/ml) significantly inhibited proliferation of SW1116 cells in a parallelly, cell cycle arrest was increased at the G0/G1 phase after salidroside treatment. Furthermore, salidroside inhibited migration and invasion of SW1116 cells. Salidroside treatment decreased proteins expression of phosphorylation levels in JAK2/STAT3 signaling, while MMP-2 and MMP-9 proteins levels were decreased and protein expression of VEGF and VEGFR-2 were down-regulated. In Conclusion, salidroside inhibited proliferation, decreased the migration and invasion of SW1116 cells in JAK2/STAT3-dependent pathway, the specific mechanisms need further study.