Synergistic anti-tumor effect of combined inhibition of EGFR and JAK/STAT3 pathways in human ovarian cancer

Enhancing the therapeutic efficacy of gefitinib on subcutaneously transplanted SKOV3 ovarian cancer tumors in nude mice via ultrasound‑stimulated microbubble cavitation

The present study aimed to explore the effect of ultrasound-stimulated microbubble cavitation (USMC) on drug concentration and therapeutic efficacy of oral gefitinib in treating subcutaneously transplanted SKOV3 ovarian cancer tumors in nude mice. The present study employed the VINNO70 ultrasonic diagnostic and treatment integrated machine for USMC therapy. Firstly, the mechanical index was set at 0.25, and the therapeutic efficacy of USMC treatment was assessed at intervals of 5, 10 and 20 min. Briefly, 72 nude mice were randomized into the following four groups (n=18/group): Control group, USMC5 min group, USMC10 min group and USMC20 min group, and the therapeutic response to USMC treatment was evaluated by comparing pre-and post-intervention effects. Additionally, the combined therapeutic efficacy of USMC and gefitinib was investigated by randomly dividing 96 tumor-bearing mice into the following four groups (n=24/group): Control group, USMC group, gefitinib group and USMC + gefitinib group. Contrast-enhanced ultrasound, hematoxylin and eosin staining, western blotting, immunofluorescence staining, TUNEL staining, ELISA and liquid chromatography-mass spectrometry were performed in the present study. The results showed that USMC combined with gefitinib had the best treatment effect; the tumor inhibition rate was higher than that of gefitinib alone and the overall survival time was prolonged. In addition, the drug concentration in the tumor tissue obtained from the USMC + gefitinib group was revealed to be ~1.4 times higher than that detected in the group treated with gefitinib alone. The experimental results also confirmed that the strongest tumor inhibition rate and longest overall survival time was observed in the USMC + gefitinib group, followed by the gefitinib group and USMC group. STAT3 is an important signaling transducer and transcription factor, which, when phosphorylated, can lead to abnormal cell proliferation and malignant transformation. In addition, the upregulation of phosphorylated (p)-STAT3 is consider a reason for the poor efficacy of gefitinib in treating ovarian cancer. The present study revealed that ultrasound microbubble therapy could overcome this side effect. In conclusion, USMC improved the effects of oral gefitinib on subcutaneously transplanted SKOV3 ovarian cancer tumors in nude mice and increased drug penetration. In addition, USMC overcame the gefitinib-induced side effect of upregulated STAT3 phosphorylation and reduced the expression levels of p-STAT3 in the tumor.

Induction of Multiple Alternative Mitogenic Signaling Pathways Accompanies the Emergence of Drug-Tolerant Cancer Cells

Drug resistance can evolve from a subpopulation of cancer cells that initially survive drug treatment and then gradually form a pool of drug-tolerant cells. Several studies have pinpointed the activation of a specific bypass pathway that appears to provide the critical therapeutic target for preventing drug tolerance. Here, we take a systems-biology approach, using proteomics and genomics to examine the development of drug tolerance to EGFR inhibitors in EGFR-mutant lung adenocarcinoma cells and BRAF inhibitors in BRAF-mutant melanoma cells. We found that there are numerous alternative mitogenic pathways that become activated in both cases, including YAP, STAT3, IGFR1, and phospholipase C (PLC)/protein kinase C (PKC) pathways. Our results suggest that an effective therapeutic strategy to prevent drug tolerance will need to take multiple alternative mitogenic pathways into account rather than focusing on one specific pathway.

Unraveling the complexity of STAT3 in cancer: molecular understanding and drug discovery

Signal transducer and activator of transcription 3 (STAT3) is a transcriptional factor involved in almost all cancer hallmark features including tumor proliferation, metastasis, angiogenesis, immunosuppression, tumor inflammation, metabolism reprogramming, drug resistance, cancer stemness. Therefore, STAT3 has become a promising therapeutic target in a wide range of cancers. This review focuses on the up-to-date knowledge of STAT3 signaling in cancer. We summarize both the positive and negative modulators of STAT3 together with the cancer hallmarks involving activities regulated by STAT3 and highlight its extremely sophisticated regulation on immunosuppression in tumor microenvironment and metabolic reprogramming. Direct and indirect inhibitors of STAT3 in preclinical and clinical studies also have been summarized and discussed. Additionally, we highlight and propose new strategies of targeting STAT3 and STAT3-based combinations with established chemotherapy, targeted therapy, immunotherapy and combination therapy. These efforts may provide new perspectives for STAT3-based target therapy in cancer.

Potential drug repurposing of ruxolitinib to inhibit the JAK/STAT pathway for the treatment of patients with epithelial ovarian cancer

AIM

This review aimed to describe the potential for therapeutic targeting of the JAK/STAT signaling pathway by repurposing the clinically-approved JAK inhibitor ruxolitinib in the patients with epithelial ovarian cancer (OC) setting.

METHODS

We reviewed publications that focus on the inhibition of the JAK/STAT pathway in hematological and solid malignancies including OC.

RESULTS

Preclinical studies showed that ruxolitinib effectively reduces OC cell viability and metastasis and enhances the anti-tumor activity of chemotherapy drugs. There are a number of recent clinical trials exploring the role of JAK/STAT inhibition in solid cancers including OC. Early results have not adequately supported efficacy in solid tumors. However, there are preclinical data and clinical studies supporting the use of ruxolitinib in combination with both chemotherapy and other targeted drugs in OC setting.

CONCLUSION

Inflammatory conditions and persistent activation of the JAK/STAT pathway are associated with tumourigenesis and chemoresistance, and therapeutic blockade of this pathway shows promising results. For women with OC, clinical investigation exploring the role of ruxolitinib in combination with chemotherapy agents or other targeted therapeutics is warranted.

SLC14A1 is a new biomarker in renal cancer

BACKGROUND

Renal cancer is one of the common malignant tumors of the urinary tract, prone to distant metastasis and drug resistance, with a poor clinical prognosis. SLC14A1 belongs to the solute transporter family, which plays a role in urinary concentration and urea nitrogen recycling in the renal, and is closely associated with the development of a variety of tumors.

METHODS

Transcription data for renal clear cell carcinoma (KIRC) were obtained from the public databases Gene Expression Omnibus database (GEO) and The Cancer Genome Atlas (TCGA), and we investigated the differences in SLC14A1 expression in cancerous and normal tissues of renal cancer, its correlation with the clinicopathological features of renal cancer patients. Then, we verified the expression levels of SLC14A1 in renal cancer tissues and their Paracancerous tissues using RT-PCR, Western-blotting and immunohistochemistry. Finally, we used renal endothelial cell line HEK-293 and renal cancer cell lines 786-O and ACHN to explore the effects of SLC14A1 on the biological behaviors of renal cancer cell proliferation, invasion and metastasis using EDU, MTT proliferation assay, Transwell invasion assay and scratch healing assay.

RESULTS

SLC14A1 was lowly expressed in renal cancer tissues and this was further validated by RT-PCR, Western blotting, and immunohistochemistry in our clinical samples. Analysis of KIRC single-cell data suggested that SLC14A1 was mainly expressed in endothelial cells. Survival analysis showed that low levels of SLC14A1 expression were associated with a better clinical prognosis. In biological behavioral studies, we found that upregulation of SLC14A1 expression levels inhibited the proliferation, invasion, and metastatic ability of renal cancer cells.

CONCLUSION

SLC14A1 plays an important role in the progression of renal cancer and has the potential to become a new biomarker for renal cancer.

Targeting receptor tyrosine kinases in ovarian cancer: Genomic dysregulation, clinical evaluation of inhibitors, and potential for combinatorial therapies

Epithelial ovarian cancer (EOC) remains one of the leading causes of cancer-related deaths among women worldwide. Receptor tyrosine kinases (RTKs) have long been sought as therapeutic targets for EOC, as they are frequently hyperactivated in primary tumors and drive disease relapse, progression, and metastasis. More recently, these oncogenic drivers have been implicated in EOC response to poly(ADP-ribose) polymerase (PARP) inhibitors and epigenome-interfering agents. This evidence revives RTKs as promising targets for therapeutic intervention of EOC. This review summarizes recent studies on the role of RTKs in EOC malignancy and the use of their inhibitors for clinical treatment. Our focus is on the ERBB family, c-Met, and VEGFR, as they are linked to drug resistance and targetable using commercially available drugs. The importance of these RTKs and their inhibitors is highlighted by their impact on signal transduction and intratumoral heterogeneity in EOC and successful use as maintenance therapy in the clinic through suppression of the VEGF/VEGFR axis. Finally, the therapeutic potential of RTK inhibitors is discussed in the context of combinatorial targeting via co-inhibiting proliferative and anti-apoptotic pathways, epigenomic/transcriptional programs, and harnessing the efficacy of PARP inhibitors and programmed cell death 1/ligand 1 immune checkpoint therapies.

Efficacy evaluation of multi-immunotherapy in ovarian cancer: From bench to bed

Ovarian cancer, one of the most common gynecological malignancies, is characterized by high mortality and poor prognosis. Cytoreductive surgery and chemotherapy remain the mainstay of ovarian cancer treatment, and most women experience recurrence after standard care therapies. There is compelling evidence that ovarian cancer is an immunogenic tumor. For example, the accumulation of tumor-infiltrating lymphocytes is associated with increased survival, while increases in immunosuppressive regulatory T cells are correlated with poor clinical outcomes. Therefore, immunotherapies targeting components of the tumor microenvironment have been gradually integrated into the existing treatment options, including immune checkpoint blockade, adoptive cell therapy, and cancer vaccines. Immunotherapies have changed guidelines for maintenance treatment and established a new paradigm in ovarian cancer treatment. Despite single immunotherapies targeting DNA repair mechanisms, immune checkpoints, and angiogenesis bringing inspiring efficacy, only a subset of patients can benefit much from it. Thus, the multi-immunotherapy investigation remains an active area for ovarian cancer treatment. The current review provides an overview of various clinically oriented forms of multi-immunotherapy and explores potentially effective combinational therapies for ovarian cancer.

Triazole-estradiol analogs: A potential cancer therapeutic targeting ovarian and colorectal cancer

1,2,3-triazoles have continuously shown effectiveness as biologically active systems towards various cancers, and when used in combination with steroid skeletons as a carrier, which can act as a drug delivery system, allows for a creation of a novel set of analogs that may be useful as a pharmacophore leading to a potential treatment option for cancer. A common molecular target for cancer inhibition is that of the Epidermal Growth Factor Receptor/Mitogen Activated Protein Kinase pathways, as inhibition of these proteins is associated with a decrease in cell viability. Estradiol-Triazole analogs were thus designed using a molecular modeling approach. Thirteen of the high scoring analogs were then synthesized and tested in-vitro on an ovarian cancer cell line (A2780) and colorectal cancer cell line (HT-29). The most active compound, Fz25, shows low micromolar activity in both the ovarian (15.29 ± 2.19 µM) and colorectal lines (15.98 ± 0.39 µM). Mechanism of action studies proved that Fz25 moderately arrests cells in the G1 phase of the cell cycle, specifically inhibiting STAT3 in both cell lines. Additionally, Fz57 shows activity in the colorectal line (24.19 ± 1.37 µM). Inhibition studies in both cell lines show inhibition against various proteins in the EGFR pathway, namely EGFR, STAT3, ERK, and mTOR. To further study their effects as therapeutics, Fz25 and Fz57 were studied against drug efflux proteins, which are associated with drug resistance, and were found to inhibit the ABC transporter P-glycoprotein. We can conclude that these estradiol-triazole analogs provide a key for future studies targeting protein inhibition and drug resistance in cancer.

ADAMTS9-AS1 Constrains Breast Cancer Cell Invasion and Proliferation via Sequestering miR-301b-3p

Objective: For determination of how ADAMTS9-AS1/miR-301b-3p/TGFBR2/JAK STAT signaling axis modulates progression of breast cancer cells.

Methods: Target lncRNA was determined by differential analysis of breast cancer expression data and survival analysis. Differentially expressed miRNAs and target mRNAs that had binding sites with target lncRNA were predicted. GSEA software was used to carry out pathway enrichment analysis for mRNAs. Binding of the researched genes were tested with RNA binding protein immunoprecipitation (RIP). How miR-301b-3p bound TGFBR2 mRNA was tested by dual-luciferase method. Transwell, colony formation, EdU approaches were employed for verification of invasion and proliferation of breast cancer cells in each treatment group.

Results: Markedly inactivated ADAMTS9-AS1 in breast cancer pertained to patient’s prognosis. MiR-301b-3p was capable of binding TGFBR2/ADAMTS9-AS1. However, overexpression of ADAMTS9-AS1 stimulated miR-301b-3p binding ADAMTS9-AS1 and repressed miR-301b-3p binding TGFBR2 mRNA. ADAMTS9-AS1 interference enhanced cancer proliferation and invasion, facilitated levels of KI67, PCNA, MMP-9 and MMP-2, and activated the JAK STAT signaling pathway. While silencing miR-301b-3p reversed the effect of ADAMTS9-AS1 interference. In addition, TGFBR2 interference or restraining JAK STAT signaling counteracted the effect of ADAMTS9-AS1.

Conclusion: ADAMTS9-AS1 could sequester miR-301b-3p to inhibit progression of breast cancer via TGFBR2/JAK STAT pathway. This study supplies a rationale for incremental apprehension of ADAMTS9-AS1 in breast cancer progression.

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

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

Exosomal transfer of miR-429 confers chemoresistance in epithelial ovarian cancer

The development of multidrug resistance during chemotherapy is the main obstacle for epithelial ovarian cancer (EOC) treatment. Exosomal transfer of carcinogenic microRNAs (miRNAs) might strengthen chemoresistance in recipient cells. Here, we identified through microarray analysis higher miR-429 expression in multidrug-resistant SKOV3 cells and their secreted exosomes (SKOV3-EXO) than in sensitive A2780 cells and their secreted exosomes. SKOV3-derived exosomes were internalized by A2780 cells, which permitted the transfer of miR-429. Exosomal miR-429 enhanced the proliferation and drug resistance of A2780 cells by targeting calcium-sensing receptor (CASR)/STAT3 pathway in vitro and in vivo. In addition, NF-κB-p65 was predicted to bind to the miR-429 promoter region, and the inhibition of NF-κB reduced the expression of miR-429 and led to the sensitivity of EOC cells. Consistently, A2780 cells co-incubated with SKOV3 pretreated with an NF-κB inhibitor or miR-429 antagomir showed sensitivity to cisplatin and exhibited attenuated cell proliferation. Based on our data, exosomal miR-429 functions as a primary regulator of the chemoresistance and malignant phenotypes of EOC by targeting CASR through a mechanism promoted by NF-κB and might be a therapeutic target for EOC.

SphK1 Promotes Cancer Progression through Activating JAK/STAT Pathway and Up-Regulating S1PR1 Expression in Colon Cancer Cells

BACKGROUND

SphK1 is a conserved lipid kinase, which can catalyze formation of tumor promoting factor sphingosine phosphate-1 (S1P).

OBJECTIVE

To investigate effect of SphK1 on proliferation/migration of colon cancer cells and associated mechanisms.

METHODS

Transcription of SphK1 gene in colon cancer cells was detected. Gene transcription of SphK1 was inhibited by transfecting with si-SphK1 gene in colon cancer cells. Effects of SphK1 inhibition (si-SphK1) on cell migration/proliferation were detected using transwell system and MTS. Gene transcription of SIP, S1PR1, S1PR2, S1PR3, and activation of JAK/STAT3 pathway were examined using RT-PCR and western blot assay. S1PR1 over-expressing plasmid was constructed and transfected into cells. Effects of S1PR1 over-expression on migration/proliferation of si-SphK1 transfected colon cancer cells and activation of JAK/STAT3 pathway were determined using RT-PCR and western blotting.

RESULTS

Gene transcription of SphK1 in SW480 and HT-29 colon cancer cells was significantly inhibited by transfection of si-SphK1 gene. Transwell migration and MTS findings showed that si-SphK1 transfection (si-SphK1 group) could reduce migration quantity and cell viability of colon cancer cells compared to negative control (NC) (p<0.0001). SphK1 inhibition (si-SphK1 group) significantly down-regulated S1PR1 and S1PR3 gene transcription in SW480 and HT-29 cells (p<0.0001), and decreased activation level of JAKSTAT3 signaling pathway compared to NC group (p<0.05). Over-expression of S1PR1 reversed inhibitory effects of si-SphK1 on migration/proliferation of SW480 and activation of JAK/Stat3.

CONCLUSION

SphK1 promoted proliferation and migration of colon cancer cells through promoting JAK/STAT activation and up-regulating S1PR1 expression.

Dual Targeting EGFR and STAT3 With Erlotinib and Alantolactone Co-Loaded PLGA Nanoparticles for Pancreatic Cancer Treatment

Pancreatic cancer (PC) is one of the most common malignancies and also a leading cause of cancer-related mortality worldwide. Many studies have shown that epidermal growth factor receptor (EGFR) is highly expressed in PC, which provides a potential target for PC treatment. However, EGFR inhibitors use alone was proven ineffective in clinical trials, due to the persistence of cellular feedback mechanisms which foster therapeutic resistance to single targeting of EGFR. Specifically, the signal transducer and activator of transcription 3 (STAT3) is over-activated when receiving an EGFR inhibitor and is believed to be highly involved in the failure and resistance of EGFR inhibitor treatment. Therein, we hypothesized that dual inhibition of EGFR and STAT3 strategy could address the STAT3 induced resistance during EGFR inhibitor treatment. To this end, we tried to develop poly (lactic-co-glycolic acid) (PLGA) nanoparticles to co-load Alantolactone (ALA, a novel STAT3 inhibitor) and Erlotinib (ERL, an EGFR inhibitor) for pancreatic cancer to test our guess. The loading ratio of ALA and ERL was firstly optimized in vitro to achieve a combined cancer-killing effect. Then, the ALA- and ERL-co-loaded nanoparticles (AE@NPs) were successfully prepared and characterized, and the related anticancer effects and cellular uptake of AE@NPs were studied. We also further detailly explored the underlying mechanisms. The results suggested that AE@NPs with uniform particle size and high drug load could induce significant pancreatic cancer cell apoptosis and display an ideal anticancer effect. Mechanism studies showed that AE@NPs inhibited the phosphorylation of both EGFR and STAT3, indicating the dual suppression of these two signaling pathways. Additionally, AE@NPs could also activate the ROS-p38 axis, which is not observed in the single drug treatments. Collectively, the AE@NPs prepared in this study possess great potential for pancreatic cancer treatment by dual suppressing of EGFR and STAT3 pathways and activating ROS-responsive p38 MAPK pathway.

Comprehensive live-cell imaging analysis of cryptotanshinone and synergistic drug-screening effects in various human and canine cancer cell lines

Background

Several studies have highlighted both the extreme anticancer effects of Cryptotanshinone (CT), a Stat3 crippling component from Salvia miltiorrhiza, as well as other STAT3 inhibitors to fight cancer.

Methods

Data presented in this experiment incorporates 2 years of in vitro studies applying a comprehensive live-cell drug-screening analysis of human and canine cancer cells exposed to CT at 20 μM concentration, as well as to other drug combinations. As previously observed in other studies, dogs are natural cancer models, given to their similarity in cancer genetics, epidemiology and disease progression compared to humans.

Results

Results obtained from several types of human and canine cancer cells exposed to CT and varied drug combinations, verified CT efficacy at combating cancer by achieving an extremely high percentage of apoptosis within 24 hours of drug exposure.

Conclusions

CT anticancer efficacy in various human and canine cancer cell lines denotes its ability to interact across different biological processes and cancer regulatory cell networks, driving inhibition of cancer cell survival.

Targeting STAT3 in Cancer Immunotherapy

As a point of convergence for numerous oncogenic signaling pathways, signal transducer and activator of transcription 3 (STAT3) is central in regulating the anti-tumor immune response. STAT3 is broadly hyperactivated both in cancer and non-cancerous cells within the tumor ecosystem and plays important roles in inhibiting the expression of crucial immune activation regulators and promoting the production of immunosuppressive factors. Therefore, targeting the STAT3 signaling pathway has emerged as a promising therapeutic strategy for numerous cancers. In this review, we outline the importance of STAT3 signaling pathway in tumorigenesis and its immune regulation, and highlight the current status for the development of STAT3-targeting therapeutic approaches. We also summarize and discuss recent advances in STAT3-based combination immunotherapy in detail. These endeavors provide new insights into the translational application of STAT3 in cancer and may contribute to the promotion of more effective treatments toward malignancies.

Synergistic Anti-Tumor Activity by Targeting Multiple Signaling Pathways in Ovarian Cancer

More effective therapy is needed to improve the survival of patients with advanced and recurrent ovarian cancer. Preclinical and early clinical studies with single molecular targeted agents have shown limited antitumor activity in ovarian cancer, likely due to compensation by alternative growth/survival pathways. An emerging strategy in overcoming resistance is to combine inhibitors targeting multiple pathways. In this study, we used a novel strategy of combining several FDA-approved targeted drugs, including sunitinib, dasatinib, and everolimus, in human ovarian cancers. Combination of the tyrosine kinase inhibitor sunitinib with the SRC inhibitor dasatinib showed synergistic anti-tumor activity in human ovarian cancer cells. The increased activity was associated with inhibition of the STAT3, SRC, and MAPK signaling pathways, but not AKT signaling. To inhibit the PI3K/AKT/mTOR pathway, we added the mTOR inhibitor everolimus, which further increased anti-tumor activity in cells. Combined treatment with sunitinib, dasatinib, and everolimus also resulted in greater inhibition of human ovarian tumor growth in mice. Furthermore, the triple combination also synergistically increased the anti-tumor activity of paclitaxel, both in vitro and in vivo. Taken together, our results demonstrate that simultaneous inhibition of several signaling pathways results in better anti-tumor activity compared to inhibiting any of these signaling pathways alone.

Lapatinib‑induced inhibition of ovarian function is counteracted by the STAT3 pathway both in vivo and in vitro

The present study was designed to ascertain whether lapatinib, a tyrosine kinase inhibitor of epidermal growth factor receptor (EGFR), affects ovarian reserve and fertility potential in a mouse model. Female C57BL/6 mice were treated with either vehicle or lapatinib (100 or 200 mg/kg/day orally) for 4 weeks, after which body weight, vaginal smears, follicle numbers, serum anti‑Müllerian hormone (AMH) levels and mating outcomes were analyzed to assess the ovarian reserve and reproductive function. Slices from the ovaries of 4‑week‑old mice were cultured with lapatinib (0, 5 or 10 µM) for 24 and 48 h, and protein expression levels were assessed to validate the changes in signaling pathways. The results indicated that mice treated with 200 mg/kg lapatinib showed a slight decrease in body weight compared to those treated with vehicle or 100 mg/kg lapatinib. There was no statistical difference in estrous cyclicity among the three groups. No significant difference was observed in follicle numbers, AMH levels, histological morphologies of the ovaries or mating outcomes in the three groups of mice. Western blotting and immunohistochemical staining of the EGF receptor and its main downstream signaling pathways showed decreased phosphorylation of EGFR and mitogen‑activated protein kinase (MAPK)3/1 and increased phosphorylation of signal transducers and activators of transcription (STAT)3 in the lapatinib‑treated groups compared to the control group. Our study suggests that lapatinib has little effect on ovarian reserve and reproductive function in a mouse model. This lack of effect of lapatinib on ovarian function may be due to the activation of the STAT3 signaling pathway that counteracts the inhibitory effects of lapatinib on EGF receptors.

NHE1 Mediates 5-Fu Resistance in Gastric Cancer via STAT3 Signaling Pathway

BACKGROUND

Several recent studies have addressed the role of Na+/H+ exchanger isoform 1 (NHE1) in tumor cell growth and apoptosis, including in gastric cancer. However, the role of NHE1 expression related to the 5-Fu resistance in gastric cancer has not been investigated.

METHODS

The expression of NHE1 was examined by qPCR in the SGC7901/5-FU cell line and its parental cell line. pcDNA3.1-NHE1 and NHE1-siRNA were transfected to SGC7901/5-FU resistance cells and cell apoptosis was detected via TUNEL assay. The upstream activators in NHE1 mediated 5-Fu resistant gastric cancer cells were detected by Western blot and immunofluorescent.

RESULTS

A significant increase of the expression of NHE1 was observed in SGC7901 5-FU resistance cells compared to the GES-1 and SGC7901 cell line. NHE1 can suppress the cell apoptosis of SGC7901 5-FU resistance cells and involved in cell cycle. Also, the migration and invasion of SGC7901 5-FU resistance cells were promoted by NHE1. NHE1 also increases the intracellular pH. The results of Western blot analysis showed that NHE1 overexpression induced an increase in the expression of phosphorylated activator transcription factor 3 (pSTAT3). The more obvious phosphorylated level was shown in the phosphorylated STAT3 at pSTAT3tyr705. Further investigations revealed that the constitutive activation of STAT3 may be induced by JAK1 and JAK2, and thus effect the 5-FU resistance by regulating NHE1.

DISCUSSION

In summary, our findings provided evidence that NHE1 contributed to 5-Fu resistance in gastric cancer cells by regulating the JAK/STAT3 pathway. Therefore, NHE1 can be a useful marker for predicting and monitoring 5-Fu resistance.

Targeting the JAK/STAT pathway in solid tumors

Aberrant activation of signal transducer and activator of transcription (STAT) proteins is associated with the development and progression of solid tumors. However, as transcription factors, these proteins are difficult to target directly. In this review, we summarize the role of targeting Janus kinases (JAKs), upstream activators of STATs, as a strategy for decreasing STAT activation in solid tumors. Preclinical studies in solid tumor cell line models show that JAK inhibitors decrease STAT activation, cell proliferation, and cell survival; in in vivo models, they also inhibit tumor growth. JAK inhibitors, particularly the JAK1/2 inhibitor ruxolitinib, sensitize cell lines and murine models to chemotherapy, immunotherapy, and oncolytic viral therapy. Ten JAK inhibitors have been or are actively being tested in clinical trials as monotherapy or in combination with other agents in patients with solid tumors; two of these inhibitors are already Food and Drug Administration (FDA) approved for the treatment of myeloproliferative disorders and rheumatoid arthritis, making them attractive agents for use in patients with solid tumors as they are known to be well-tolerated. Four JAK inhibitors (two of which are FDA approved for other indications) have exhibited promising anti-cancer effects in preclinical studies; however, clinical studies specifically assessing their activity against the JAK/STAT pathway in solid tumors have not yet been conducted. In summary, JAK inhibition is a viable option for targeting the JAK/STAT pathway in solid tumors and merits further testing in clinical trials.

BP-1-102 and silencing of Fascin-1 by RNA interference inhibits the proliferation of mouse pituitary adenoma AtT20 cells via the signal transducer and activator of transcription 3/fascin-1 pathway

INTRODUCTION

The expression levels of signal transducer and activator of transcription 3 (STAT3) protein and Fascin-1 were inhibited using the STAT3 inhibitor BP-1-102 and RNA interference, respectively, to investigate the expression of AtT20 in mouse pituitary cells. The proliferative capacity and related molecular mechanisms of pituitary tumor cells were then analyzed.

METHODS

Mouse AtT20 pituitary adenoma cells were divided into a control group (Pa group), a STAT3 inhibitor vehicle group (PA + DMSO group), a STAT3 inhibitor group (PA + BP-1-102 group), a Fascin-1 negative control group (PA + neg-siRNA group) and a Fascin-1 silenced group (PA + Fascin-siRNA group). The related protein expression and cell proliferation of the five groups were measured using immunofluorescence, Western blot and real-time RT-PCR, whereas their apoptosis and cell cycle were evaluated using CCK-8 and flow cytometry.

RESULTS

Proliferation of AtT20 cells is inhibited with BP-1-102 enhanced apoptosis, at the same time reduced the expression of Fascin-1 and N-cadherin, and increased the expression of E-cadherin. After inhibiting Fascin-1, the expression of STAT3 decreased, the expression of N-cadherin decreased and the expression of E-cadherin increased.

CONCLUSIONS

BP-1-102 is a novel drug with a great potential in pituitary tumors. Given their important roles in the growth of pituitary adenomas, STAT3 and Fascin-1 can be used as new treatment targets.

Inhibition of esophageal-carcinoma cell proliferation by genistein via suppression of JAK1/2-STAT3 and AKT/MDM2/p53 signaling pathways

Esophageal carcinoma (EsC) is a clinically challenging neoplastic disease. Genistein, a natural isoflavone product, has anti-tumor properties. Through in vitro and in vivo studies, we found that genistein suppressed EsC cell proliferation in a time- and concentration-dependent manner. In addition, genistein markedly promoted apoptosis and arrested cell cycle at the G0/G1 phase in a concentration-dependent manner. Furthermore, high concentrations of genistein have no adverse effect on normal esophageal epithelial cells. Mechanistically, genistein treatment strikingly reduced the expression of cell cycle-associated genes, and up-regulated the expression of cell apoptosis-related genes in EsC cells. Additionally, genistein dramatically decreased epidermal growth factor receptor (EGFR) expression and attenuated its down-stream signaling molecules STAT3, MDM2, Akt and JAK1/2 phosphorylation, resulting in inhibited nuclear translocation of STAT3 and MDM2, thereby inhibiting the JAK1/2-STAT3 and AKT/MDM2/p53 signaling pathways. In xenograft nude mice, genistein administration strikingly impaired tumor growth in a dose-dependent manner. Moreover, similar disturbances in molecular mechanisms were observed in vivo. Taken together, genistein suppressed the JAK1/2-STAT3 and AKT/MDM2/p53 signaling pathways by decreasing EGFR expression, leading to cell apoptosis, cell cycle arrest, and proliferation inhibition in EsC cells. Our findings suggest that genistein may be a promising alternative adjuvant therapy for patients with EsC.

Calcitriol inhibits lipopolysaccharide-induced proliferation, migration and invasion of prostate cancer cells through suppressing STAT3 signal activation

Increasing evidence suggests that infection promotes the initiation and progression of prostate cancer. This study investigated the effects of lipopolysaccharide (LPS), a major component of Gram-negative bacilli, on proliferation, migration and invasion of prostate cancer cells and the protective effects of 1α,25(OH)2D3 (calcitriol). PC-3 and DU145 cells were stimulated with LPS (2.0 μg/mL) in the presence or absence of 1α,25(OH)2D3 (100 nM). Our results shown that 1α,25(OH)2D3 reduced the proportion of S phase cells in LPS-stimulated PC-3 and DU145 cells, and down-regulated the nuclear protein levels of Cyclin D1 and PCNA in LPS-stimulated PC-3 cells. In addition, 1α,25(OH)2D3 inhibited migration and invasion, as determined by wound healing and transwell assay, in LPS-stimulated PC-3 and DU145 cells. Of interest, we observed that 1α,25(OH)2D3 inhibits NF-κB activation and subsequent synthesis and secretion of IL-6 and IL-8 by promoting VDR and NF-κB p65 interaction. Surprisingly, 1α,25(OH)2D3 blocks nuclear translocation of pSTAT3 by promoting physical interaction between VDR and pSTAT3 (Tyr705) in LPS-stimulated PC-3 and DU145 cells. These results suggest that 1α,25(OH)2D3 inhibits LPS-induced proliferation, migration and invasion in prostate cancer cells by directly and indirectly blocking STAT3 signal transduction.

EGFR blockade in GBM brain tumor stem cells synergizes with JAK2/STAT3 pathway inhibition to abrogate compensatory mechanisms in vitro and in vivo

Background

The EGFR pathway is frequently mutated in glioblastoma (GBM). However, to date, EGFR therapies have not demonstrated efficacy in clinical trials. Poor brain penetration of conventional inhibitors, lack of patient stratification for EGFR status, and mechanisms of resistance are likely responsible for the failure of EGFR-targeted therapy. We aimed to address these elements in a large panel of molecularly diverse patient-derived GBM brain tumor stem cells (BTSCs).

Methods

In vitro growth inhibition and on-target efficacy of afatinib, pacritinib, or a combination were assessed by cell viability, neurosphere formation, cytotoxicity, limiting dilution assays, and western blotting. In vivo efficacy was assessed with mass spectrometry, immunohistochemistry, magnetic resonance imaging, and intracranial xenograft models.

Results

We show that afatinib and pacritinib decreased BTSC growth and sphere-forming capacity in vitro. Combinations of the 2 drugs were synergistic and abrogated the activation of STAT3 signaling observed upon EGFR inhibition in vitro and in vivo. We further demonstrate that the brain-penetrant EGFR inhibitor, afatinib, improved survival in EGFRvIII mt orthotopic xenograft models. However, upregulation of the oncogenic STAT3 signaling pathway was observed following afatinib treatment. Combined inhibition with 2 clinically relevant drugs, afatinib and pacritinib, synergistically decreased BTSC viability and abrogated this compensatory mechanism of resistance to EGFR inhibition. A significant decrease in tumor burden in vivo was observed with the combinatorial treatment.

Conclusions

These data demonstrate that brain-penetrant combinatorial therapies targeting the EGFR and STAT3 signaling pathways hold therapeutic promise for GBM.

STAT3 signaling in ovarian cancer: a potential therapeutic target

Accumulating evidence has shown that Signal Transducer and Activator of Transcription 3 (STAT3) is thought to be a promising target for cancer therapy as STAT3 is frequently overexpressed in a wide range of cancer cells as well as clinical specimens, promoting tumor progression. It is widely accepted that STAT3 regulates a variety of cellular processes, such as tumor cell growth, survival, invasion, cancer stem cell-like characteristic, angiogenesis and drug-resistance. In this review, we focus on the role of STAT3 in tumorigenesis in ovarian cancer and discuss the existing inhibitors of STAT3 signaling that can be promisingly developed as the strategies for ovarian cancer therapy.

Targeting STAT3 in Cancer with Nucleotide Therapeutics

Signal transducer and activator of transcription 3 (STAT3) plays a critical role in promoting the proliferation and survival of tumor cells. As a ubiquitously-expressed transcription factor, STAT3 has commonly been considered an "undruggable" target for therapy; thus, much research has focused on targeting upstream pathways to reduce the expression or phosphorylation/activation of STAT3 in tumor cells. Recently, however, novel approaches have been developed to directly inhibit STAT3 in human cancers, in the hope of reducing the survival and proliferation of tumor cells. Several of these agents are nucleic acid-based, including the antisense molecule AZD9150, CpG-coupled STAT3 siRNA, G-quartet oligodeoxynucleotides (GQ-ODNs), and STAT3 decoys. While the AZD9150 and CpG-STAT3 siRNA interfere with STAT3 expression, STAT3 decoys and GQ-ODNs target constitutively activated STAT3 and modulate its ability to bind to target genes. Both STAT3 decoy and AZD9150 have advanced to clinical testing in humans. Here we will review the current understanding of the structures, mechanisms, and potential clinical utilities of the nucleic acid-based STAT3 inhibitors.

Eribulin Synergistically Increases Anti-Tumor Activity of an mTOR Inhibitor by Inhibiting pAKT/pS6K/pS6 in Triple Negative Breast Cancer

Unlike other breast cancer subtypes, patients with triple negative breast cancer (TNBC) have poor outcomes and no effective targeted therapies, leaving an unmet need for therapeutic targets. Efforts to profile these tumors have revealed the PI3K/AKT/mTOR pathway as a potential target. Activation of this pathway also contributes to resistance to anti-cancer agents, including microtubule-targeting agents. Eribulin is one such microtubule-targeting agent that is beneficial in treating taxane and anthracycline refractory breast cancer. In this study, we compared the effect of eribulin on the PI3K/AKT/mTOR pathway with other microtubule-targeting agents in TNBC. We found that the phosphorylation of AKT was suppressed by eribulin, a microtubule depolymerizing agent, but activated by paclitaxel, a microtubule stabilizing agent. The combination of eribulin and everolimus, an mTOR inhibitor, resulted in an increased reduction of p-S6K1 and p-S6, a synergistic inhibition of cell survival in vitro, and an enhanced suppression of tumor growth in two orthotopic mouse models. These findings provide a preclinical foundation for targeting both the microtubule cytoskeleton and the PI3K/AKT/mTOR pathway in the treatment of refractory TNBC.

Toxoplasma gondii induces prolonged host epidermal growth factor receptor signalling to prevent parasite elimination by autophagy: Perspectives for in vivo control of the parasite

Toxoplasma gondii causes retinitis and encephalitis. Avoiding targeting by autophagosomes is key for its survival because T. gondii cannot withstand lysosomal degradation. During invasion of host cells, T. gondii triggers epidermal growth factor receptor (EGFR) signalling enabling the parasite to avoid initial autophagic targeting. However, autophagy is a constitutive process indicating that the parasite may also use a strategy operative beyond invasion to maintain blockade of autophagic targeting. Finding that such a strategy exists would be important because it could lead to inhibition of host cell signalling as a novel approach to kill the parasite in previously infected cells and treat toxoplasmosis. We report that T. gondii induced prolonged EGFR autophosphorylation. This effect was mediated by PKCα/PKCβ ➔ Src because T. gondii caused prolonged activation of these molecules and their knockdown or incubation with inhibitors of PKCα/PKCβ or Src after host cell invasion impaired sustained EGFR autophosphorylation. Addition of EGFR tyrosine kinase inhibitor (TKI) to previously infected cells led to parasite entrapment by LC3 and LAMP-1 and pathogen killing dependent on the autophagy proteins ULK1 and Beclin 1 as well as lysosomal enzymes. Administration of gefitinib (EGFR TKI) to mice with ocular and cerebral toxoplasmosis resulted in disease control that was dependent on Beclin 1. Thus, T. gondii promotes its survival through sustained EGFR signalling driven by PKCα/β ➔ Src, and inhibition of EGFR controls pre-established toxoplasmosis.

Efficient identification of neoantigen-specific T-cell responses in advanced human ovarian cancer

Background

Efficient identification of neoantigen-specific T-cell responses in epithelial ovarian cancer (EOC) remains a challenge. Existing investigations of spontaneous T-cell response to tumor neoepitope in EOC have taken the approach of comprehensive screening all neoantigen candidates, with a validation rate of 0.5–2%.

Methods

Whole-exome and transcriptome sequencing analysis of treatment-naive EOC patients were performed to identify neoantigen candidates, and the immunogenicity of prioritized neoantigens was evaluated by analyzing spontaneous neoantigen-specfic CD4⁺ and CD8⁺ T-cell responses in the tumor and/or peripheral blood. The biological relevance of neoantigen-specific T-cell lines and clones were analyzed by evaluating the capacity of autologous ovarian tumor recognition. Genetic transfer of T-cell receptor (TCR) from these neoantigen-specific T-cell clones into peripheral blood T-cells was conducted to generate neoepitope-specific T-cells. The molecular signature associated with positive neoantigen T-cell responses was investigated, and the impacts of expression level and lymphocyte source on neoantigen identification were explored.

Results

Using a small subset of prioritized neoantigen candidates, we were able to detect spontaneous CD4⁺ and/or CD8⁺ T-cell responses against neoepitopes from autologous lymphocytes in half of treatment-naïve EOC patients, with a significantly improved validation rate of 19%. Tumors from patients exhibiting neoantigen-specific T-cell responses exhibited a signature of upregulated antigen processing and presentation machinery, which was also associated with favorable patient survival in the TCGA ovarian cohort. T-cells specific against two mutated cancer-associated genes, NUP214 and JAK1, recognized autologous tumors. Gene-engineering with TCR from these neoantigen-specific T-cell clones conferred neoantigen-reactivity to peripheral T-cells.

Conclusions

Our study demonstrated the feasibility of efficiently identifying both CD4⁺ and CD8⁺ neoantigen-specific T-cells in EOC. Autologous lymphocytes genetically engineered with tumor antigen-specific TCR can be used to generate cells for use in the personalized adoptive T-cell transfer immunotherapy.

Electronic supplementary material

The online version of this article (10.1186/s40425-019-0629-6) contains supplementary material, which is available to authorized users.

An EGFR-Induced Drosophila Lung Tumor Model Identifies Alternative Combination Treatments

Lung cancer is the leading cause of cancer-associated mortality. Mutations in the EGFR gene are among the most important inducers of lung tumor development, but success of personalized therapies is still limited because of toxicity or developing resistances. We expressed constitutively active EGFR (EGFR^CA) exclusively in the airway system of Drosophila melanogaster and performed comprehensive phenotyping. Ectopic expression of EGFR^CA induced massive hyper- and metaplasia, leading to early death. We used the lethal phenotype as a readout and screened a library of FDA-approved compounds and found that among the 1,000 compounds, only the tyrosine kinase inhibitors (TKI) afatinib, gefitinib, and ibrutinib rescued lethality in a whole-animal screening approach. Furthermore, we screened the library in the presence of a subtherapeutic afatinib dose and identified bazedoxifene as a synergistically acting compound that rescues EGFR-induced lethality. Our findings highlight the potential of Drosophila-based whole-animal screening approaches not only to identify specific EGFR inhibitors but also to discover compounds that act synergistically with known TKIs. Moreover, we showed that targeting the EGFR together with STAT-signaling is a promising strategy for lung tumor treatment.

Targeting slug-mediated non-canonical activation of c-Met to overcome chemo-resistance in metastatic ovarian cancer cells

Metastasis-associated drug resistance accounts for high mortality in ovarian cancer and remains to be a major barrier for effective treatment. In this study, SKOV3/T4, a metastatic subpopulation of ovarian cancer SKOV3 cells, was enriched to explore potential interventions against metastatic-associated drug resistance. Quantitative genomic and functional analyses were performed and found that slug was significantly increased in the SKOV3/T4 subpopulation and contributed to the high resistance of SKOV3/T4. Further studies showed that slug activated c-Met in a ligand-independent manner due to elevated levels of fibronectin and provoked integrin α V function, which was confirmed by the significant correlation of slug and p-Met levels in 121 ovarian cancer patient samples. Intriguingly, c-Met inhibitor(s) exhibited greatly enhanced anti-cancer effects in slug-positive ovarian cancer models both in vitro and in vivo. Additionally, IHC analyses revealed that slug levels were highly correlated with reduced survival of ovarian cancer patients. Taken together, this study not only uncovers the critical roles of slug in drug resistance in ovarian cancer but also highlights a promising therapeutic strategy by targeting the noncanonical activation of c-Met in slug-positive ovarian cancer patients with poor prognosis.

Overexpression of SOCS3 mediated by adenovirus vector in mouse and human castration-resistant prostate cancer cells increases the sensitivity to NK cells in vitro and in vivo

Prostate cancer is one of the most common cancers in men. The overactivation of IL-6/JAK/STAT3 signaling and silencing of SOCS3 are frequently observed in prostate cancer. In the present study we undertook to develop Ad-SOCS3 gene therapy for the treatment of prostate cancer and also investigated whether Ad-SOCS3 increased sensitivity to NK cells. We demonstrated that Ad-SOCS3 could significantly inhibit growth of castration-resistant prostate cancer (CRPC) cell lines expressing pSTAT3, DU-145 (at 10, 20, and 40 MOI), and TRAMP-C2 (at 40 MOI), but not the PC-3 CRPC cell line with the STAT3 gene deleted. Ad-SOCS3 (40 MOI) could suppress IL-6 production in DU-145 cells and PD-L1 expression induced by IFN-γ in TRAMP-C2 cells, and increased the NK cell sensitivity of both TRAMP-C2 and DU-145 cells. In the DU-145 mouse xenograft tumor model, intratumoral injections (twice/week for 3 weeks) of 1 × 10⁸ pfu of Ad-SOCS3 significantly inhibited tumor growth and combining the Ad-SOCS3 treatment with intratumoral injections (once/week for 2 weeks) of 1 × 10⁷ human NK cells showed the highest tumor growth inhibitory effect. These results suggested that a combination of Ad-SOCS3 gene therapy and NK cell immunotherapy could be a powerful treatment option for advanced CRPC overexpressing pSTAT3.

IL-6 and ovarian cancer: inflammatory cytokines in promotion of metastasis

Ovarian cancer is the most fatal gynecological cancer in the USA and the fifth most common cancer-related cause of death in women. Inflammation has been shown to play many roles in ovarian cancer tumor growth, with the proinflammatory cytokine interleukin-6 (IL-6) having been established as a key immunoregulatory cytokine. Ovarian cancer cells continuously secrete cytokines that promote tumorigenicity in both autocrine and paracrine fashions while also receiving signals from the tumor microenvironment (TME). The TME contains many cells including leukocytes and fibroblasts, which respond to proinflammatory cytokines and secrete their own cytokines, which can produce many effects including promotion of chemoresistance, resistance to apoptosis, invasion, angiogenesis by way of overexpression of vascular endothelial growth factor, and promotion of metastatic growth at distant sites. IL-6 and its proinflammatory family members, including oncostatin M, have been found to directly stimulate enhanced invasion of cancer cells through basement membrane degradation caused by the overexpression of matrix metalloproteinases, stimulate promotion of cell cycle, enhance resistance to chemotherapy, and cause epithelial-to-mesenchymal transition (EMT). IL-6 has been shown to activate signaling pathways that lead to tumor proliferation, the most studied of which being the Janus kinase (JAK) and STAT3 pathway. IL-6-induced JAK/STAT activation leads to constitutive activation of STAT3, which has been correlated with enhanced tumor cell growth and resistance to chemotherapy. IL-6 has also been shown to act as a trigger of the EMT, the hypothesized first step in the metastatic cascade. Understanding the important role of IL-6 and its family members' effects on the pathogenesis of ovarian cancer tumor growth and metastasis may lead to more novel treatments, detection methods, and improvement of overall clinical outcomes.

A natural ent‑kaurane diterpenoid induces antiproliferation in ovarian cancer cells via ERK1/2 regulation and inhibition of cellular migration and invasion

Ovarian cancer is one of the most common causes of female mortalities from gynecological tumors. An ent‑kaurane diterpenoid compound CRT1 (ent‑18‑acetoxy‑7β‑hydroxy kaur‑15‑oxo‑16‑ene), mainly isolated from the Vietnamese herb Croton tonkinesis has been used in folk medicine in Vietnam for cancer treatment. However, the effect of this compound on human ovarian cancer cells has not yet been reported. The objective of the present study was to determine the effect of CRT1 on the cell viability, apoptosis and metastasis of SKOV3 human ovarian cancer cells using a Cell Counting Kit‑8 assay, flow cytometric analysis of Annexin V‑fluorescein isothiocyanate/propidium iodide staining, western blot analysis, soft agar colony forming assay, wound healing assay and Matrigel invasion assay. The results revealed that CRT1 possessed significant anti‑proliferative effects on SKOV3 cells. CRT1 treatment at 25 and 50 µM induced apoptosis, enhanced the percentage of Annexin V‑positive cells, increased the expression of pro‑apoptotic protein B‑cell lymphoma 2 (Bcl‑2)‑associated X protein, cytochrome c release from the mitochondria to the cytosol, cleaved caspase‑3, caspase‑7, caspase‑9, and poly (adenosine diphosphate‑ribose) polymerase. However, it decreased the expression of Bcl‑2 in a dose‑dependent manner. The percentage of necrotic cells increased following CRT1 treatment at <10 µM. CRT1 at 50 µM significantly induced the phosphorylation of extracellular signal‑regulated kinase (ERK). Growth inhibition and the apoptotic effects of CRT1 could be reversed by PD98059, an ERK inhibitor. Additionally, CRT1 inhibited cell migration and invasion via ERK1/2 activation in SKOV3 cells. These results indicated that CRT1, an ent‑kaurane diterpenoid, may be a potential inhibitor of ovarian cancer by the activating ERK1/2/p90 ribosomal S6 kinase signaling pathway.

Proteomic analysis of canine oral tumor tissues using MALDI-TOF mass spectrometry and in-gel digestion coupled with mass spectrometry (GeLC MS/MS) approaches

Oral tumors, including highly invasive and metastatic oral melanoma (OM), non-tonsillar oral squamous cell carcinoma (OSCC) and benign tumors (BN), are common neoplasms in dogs. Although these tumors behave differently, limited data of their protein expression profiles have been exhibited, particularly at the proteome level. The present study aimed to i.) characterize peptide-mass fingerprints (PMFs) and identify potential protein candidates of OM, OSCC, BN and normal control subjects, using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) and liquid chromatography tandem mass spectrometry (LC-MS/MS), ii.) identify potential protein candidates associated with the diseases, using in-gel digestion coupled with mass spectrometric analysis (GeLC-MS/MS) and iii.) search for relationships between chemotherapy drugs and disease-perturbed proteins. A distinct cluster of each sample group and unique PMFs with identified protein candidates were revealed. The unique peptide fragment at 2,274 Da of sacsin molecular chaperone (SACS) was observed in early-stage OM whereas the fragment at 1,958 Da of sodium voltage-gated channel alpha subunit 10 (SCN10A) was presented in early- and late-stage OM. The peptide mass at 2,316 Da of Notch1 appeared in early-stage OM and benign oral tumors while the peptide mass at 2,505 Da of glutamate ionotropic receptor N-methyl-D-aspartate type subunit 3A (GRIN3A) was identified in all groups. Markedly expressed proteins from GeLC-MS/MS included Jumonji domain containing 1C (JMJD1C) in benign tumors, inversin (INVS) and rho guanine nucleotide exchange factor 28 (ARHGEF28) in OM, BTB domain-containing 16 (BTBD16) in OSCC, and protein tyrosine phosphatase non-receptor type 1 (PTPN1), BRCA2, DNA repair associated (BRCA2), WW domain binding protein 2 (WBP2), purinergic receptor P2Y1 and proteasome activator subunit 4 (PSME4) in all cancerous groups. The network connections between these proteins and chemotherapy drugs, cisplatin and doxorubicin, were also demonstrated. In conclusion, this study unveiled the unique PMFs and novel candidate protein markers of canine oral tumors.

Pterostilbene Suppresses Ovarian Cancer Growth via Induction of Apoptosis and Blockade of Cell Cycle Progression Involving Inhibition of the STAT3 Pathway

A growing body of evidence has demonstrated the promising anti-tumor effects of resveratrol in ovarian cancer cells, including its inhibitory effects on STAT3 activation. Nonetheless, the low bioavailability of resveratrol has reduced its attractiveness as a potential anti-cancer treatment. In contrast, pterostilbene, a stilbenoid and resveratrol analog, has demonstrated superior bioavailability, while possessing significant antitumor activity in multiple solid tumors. In this study, the therapeutic potential of pterostilbene was evaluated in ovarian cancer cells. Pterostilbene reduces cell viability in several different ovarian cancer cell lines by suppressing cell cycle progression and inducing apoptosis. Further molecular study has shown that pterostilbene effectively suppressed phosphorylation of STAT3, as well as STAT3 downstream genes that regulate cell cycle and apoptosis, indicating that inhibition of STAT3 pathway may be involved in its anti-tumor activity. The addition of pterostilbene to the commonly used chemotherapy cisplatin demonstrated synergistic antiproliferative activity in several ovarian cancer cell lines. Pterostilbene additionally inhibited cell migration in multiple ovarian cancer cell lines. The above results suggest that pterostilbene facilitates significant anti-tumor activity in ovarian cancer via anti-proliferative and pro-apoptotic mechanisms, possibly via downregulation of JAK/STAT3 pathway. Pterostilbene thus presents as an attractive non-toxic alternative for potential adjuvant or maintenance chemotherapy in ovarian cancer.

Biochemical Properties of a Decoy Oligodeoxynucleotide Inhibitor of STAT3 Transcription Factor

Cyclic STAT3 decoy (CS3D) is a second-generation, double-stranded oligodeoxynucleotide (ODN) that mimics a genomic response element for signal transducer and activator of transcription 3 (STAT3), an oncogenic transcription factor. CS3D competitively inhibits STAT3 binding to target gene promoters, resulting in decreased expression of proteins that promote cellular proliferation and survival. Previous studies have demonstrated antitumor activity of CS3D in preclinical models of solid tumors. However, prior to entering human clinical trials, the efficiency of generating the CS3D molecule and its stability in biological fluids should be determined. CS3D is synthesized as a single-stranded ODN and must have its free ends ligated to generate the final cyclic form. In this study, we report a ligation efficiency of nearly 95 percent. The ligated CS3D demonstrated a half-life of 7.9 h in human serum, indicating adequate stability for intravenous delivery. These results provide requisite biochemical characterization of CS3D that will inform upcoming clinical trials.

Novel multiple tyrosine kinase inhibitor ponatinib inhibits bFGF-activated signaling in neuroblastoma cells and suppresses neuroblastoma growth in vivo

Neuroblastoma (NB) is one of the most common pediatric malignancies in children. Abnormal activation of receptor tyrosine kinases contributes to the pathological development of NB. Therefore, targeting tyrosine kinase receptors to cure NB is a promising strategy. Here, we report that a multi-targeted tyrosine kinase inhibitor ponatinib inhibited NB cell proliferation and induced NB cell apoptosis in a dose-dependent manner. In addition, ponatinib suppressed the colony formation ability of NB cells. Mechanistically, ponatinib effectively inhibited the FGFR1-activated signaling pathway. Ponatinib also enhanced the cytotoxic effects of doxorubicin on NB cells. Furthermore, ponatinib demonstrated anti-tumor efficacy in vivo by inhibiting tumor growth in an orthotopic xenograft NB mouse model. In summary, our results showed that ponatinib inhibited NB growth both in vitro and in vivo.

Ruxolitinib synergistically enhances the anti-tumor activity of paclitaxel in human ovarian cancer

Treatment for ovarian cancer remains challenging despite a high initial response rate to first line platinum-taxane treatment. Most patients eventually experience recurrence and require further treatment. Persistent activation of STAT3 is associated with cancer growth and progression and is also involved in cell resistance to platinum and taxane treatment. Targeting JAK/STAT3, therefore, could be a potential novel therapeutic approach for treating advanced and chemoresistant ovarian cancer. We investigated the therapeutic potential of ruxolitinib, a JAK1/JAK2 inhibitor that has been FDA-approved for the treatment of myelofibrosis, to treat ovarian cancer either alone or in combination with conventional chemotherapy agents. We show that ruxolitinib inhibits STAT3 activation and ovarian tumor growth both in ovarian cancer cells and in an ovarian cancer mouse model. In addition, ruxolitinib significantly increases the anti-tumor activity of chemotherapy agents, including paclitaxel, cisplatin, carboplatin, doxorubicin and topotecan in ovarian cancer cells. Evaluation of the combination index (CI) shows that ruxolitinib synergistically interacts with paclitaxel in all three human ovarian cancer cells. Finally, our results demonstrate that combination of ruxolitinib and paclitaxel leads to a greater reduction of tumor growth compared to single treatment of either agent in a tumor mouse model that represents late stage ovarian cancer with peritoneal metastasis and ascites formation. Taken together, our findings provide a foundation for clinical trials with ruxolitinib, either as a single agent or in combination with paclitaxel, for the treatment of recurrent and advanced ovarian cancer.

Long non-coding RNA H19 suppresses retinoblastoma progression via counteracting miR-17-92 cluster

Long non-coding RNAs (lncRNAs) are frequently dysregulated and play important roles in many cancers. lncRNA H19 is one of the earliest discovered lncRNAs which has diverse roles in different cancers. However, the expression, roles, and action mechanisms of H19 in retinoblastoma are still largely unknown. In this study, we found that H19 is downregulated in retinoblastoma tissues and cell lines. Gain-of-function and loss-of-function assays showed that H19 inhibits retinoblastoma cell proliferation, induces retinoblastoma cell cycle arrest and cell apoptosis. Mechanistically, we identified seven miR-17-92 cluster binding sites on H19, and found that H19 directly bound to miR-17-92 cluster via these seven binding sites. Through binding to miR-17-92 cluster, H19 relieves the suppressing roles of miR-17-92 cluster on p21. Furthermore, H19 represses STAT3 activation induced by miR-17-92 cluster. Hence, our results revealed that H19 upregulates p21 expression, inhibits STAT3 phosphorylation, and downregulates the expression of STAT3 target genes BCL2, BCL2L1, and BIRC5. In addition, functional assays demonstrated that the mutation of miR-17-92 cluster binding sites on H19 abolished the proliferation inhibiting, cell cycle arrest and cell apoptosis inducing roles of H19 in retinoblastoma. In conclusion, our data suggested that H19 inhibits retinoblastoma progression via counteracting the roles of miR-17-92 cluster, and implied that enhancing the action of H19 may be a promising therapeutic strategy for retinoblastoma.

Correlation between NM23 protein overexpression and prognostic value and clinicopathologic features of ovarian cancer: a meta-analysis

OBJECTIVE

The prognostic value and clinicopathological features of NM23 (non-metastasis 23) have previously been assessed, but the results are controversial. Here, we attempted to clarify the correlation between NM23 expression and its prognostic value and the clinicopathological features in ovarian cancer (OC).

METHODS

The relevant studies were identified using PubMed, Embase, and Web of Science. We calculated the pooled odds ratio (OR) with 95% confidence intervals (CIs) for overall survival (OS), progression-free survival (PFS), and clinicopathological features. We used OS to evaluate the prognostic value of NM23 expression in patients with OC. Subgroup analyses were used to explore the source of heterogeneity.

RESULTS

We included 10 studies involving 894 patients in our assessment of the association between NM23 expression and OS for OC. Our data indicated that NM23 expression was not associated with improved OS (OR 0.83, 95% CI 0.41-1.68, P = 0.61) or PFS (OR 0.7, 95% CI 0.39-1.24, P = 0.22). Elevated NM23 expression was associated with differentiation grade (OR 0.35, 95% CI 0.2-0.6, P = 0.0002) and N status (OR 0.33, 95% CI 0.14-0.78, P = 0.01), whereas there was no significant difference between NM23 expression and tumor stage (OR 1.1, 95% CI 0.45-2.66, P = 0.84). Subgroup analysis did not reveal any potential source of heterogeneity. No obvious publication bias was found.

CONCLUSIONS

In OC, there is poor statistical significance between NM23 expression and OS and PFS, but NM23 expression is related to differentiation grade and N status. This meta-analysis reveals that NM23 expression is a potential factor of poor prognosis in OC. The prognostic role of NM23 in different OC stages in combination with the clinical characteristics suggests a novel approach for developing future therapeutic targets.

Overcoming resistance of targeted EGFR monotherapy by inhibition of STAT3 escape pathway in soft tissue sarcoma

Although epidermal growth factor receptor (EGFR) is often over-expressed in soft tissue sarcoma (STS), a phase II trial using an EGFR inhibitor gefitinib showed a low response rate. This study identified a new secondary resistance mechanism of gefitinib in STS, and developed new strategies to improve the effectiveness of EGFR inhibition particularly by blocking the STAT3 pathway.

We demonstrated that seven STS cell lines of diverse histological origin showed resistance to gefitinib despite blockade of phosphorylated EGFR (pEGFR) and downstream signal transducers (pAKT and pERK) in PI3K/AKT and RAS/ERK pathways. Gefitinib exposure was not associated with decrease in the ratio of pSTAT3/pSTAT1. The relative STAT3 abundance and activation may be responsible for the drug resistance. We therefore hypothesized that the addition of a STAT3 inhibitor could overcome the STAT3 escape pathway.

We found that the addition of STAT3 inhibitor S3I-201 to gefitinib achieved synergistic anti-proliferative and pro-apoptotic effects in all three STS cell lines examined. This was confirmed in a fibrosarcoma xenografted mouse model, where the tumours from the combination group (418mm³) were significantly smaller than those from untreated (1032mm³) or single drug (912 and 798mm³) groups.

Our findings may have clinical implications for optimising EGFR-targeted therapy in STS.

Cucurbitacin B and cancer intervention: Chemistry, biology and mechanisms (Review)

Cancer is one of the most important healthcare matters, with the worst prognosis but the best possibilities for scientific development. It is likely to increase in the future and cause global havoc designating it as an epidemic. Cancer development requires urgent intervention. Past few decades have witnessed extensive research to challenge carcinogenesis. Treatment involving synthetic discipline is often associated with severe adverse effects, or even worsened prognosis. Accordingly, newer economic and patient friendly molecules are warranted. Many natural substances have proved their potential so far. Cucurbitacin B against cancer and other diseases has achieved towering popularity among the researchers around the world, as detailed in the below sections with summarized tables. In line with the fascinating role of cucurbitacin B against various types of cancers, through various molecular signaling pathways, it is justifiable to propose cucurbitacin B as a mainline chemotherapy before the onset and after the diagnosis of cancer.

Cx32 inhibits TNFα-induced extrinsic apoptosis with and without EGFR suppression

Tumor necrosis factor α (TNFα) and TNF-related apoptosis-inducing ligand (TRAIL) can trigger the extrinsic apoptosis pathway. Our previous study indicated that connexin32 (Cx32) inhibited streptonigrin-induced intrinsic apoptosis via the epidermal growth factor receptor (EGFR) pathway. However, whether Cx32 can exert effects on the extrinsic apoptosis pathway through EGFR signaling remains unclear. In the present study, we investigated the role of Cx32 in extrinsic apoptosis induced by treatment with TNFα + cycloheximide (CHX) or afatinib in human cervical cancer (CaCx) cells. In stable inducible Cx32-transfected HeLa cells (HeLa-Cx32), Cx32 expression was induced by treatment with doxycycline (Dox). Furthermore, C-33A cells, which natively express high levels of Cx32, were used as a cell model for knockdown of Cx32 with siRNA. To determine the non-junctional function of Cx32 in apoptosis, 18α-glycyrrhetinic acid (18α-GA), a gap junction intracellular communication (GJIC) inhibitor, was used. Our results showed that Cx32 could inhibit apoptosis induced by TNFα + afatinib with or without the GJIC inhibitor. In clinical cervical tissue samples, we found that the expression of survivin was markedly higher in CaCx than in normal cervix tissue, which was in accordance with the expression of Cx32 in our previous study. In HeLa-Cx32 cells, we also found that Cx32 upregulated the expression of Cox-2. In addition, Cx32 upregulated EGFR expression in low-density culture (lacking GJ formation). Cx32 could also promote the expression of EGFR, phospho-STAT3 and phospho-ERK in HeLa-Cx32 cells following TNFα treatment. After knocking down Cx32 in C-33A cells, the expression levels of survivin and TNFα were downregulated. The present study verifies that Cx32 exerts an inhibitory effect on extrinsic apoptosis in CaCx cells, and suggests that Cx32 may regulate the progression and micro-environment of CaCx cells.

Kinome and Transcriptome Profiling Reveal Broad and Distinct Activities of Erlotinib, Sunitinib, and Sorafenib in the Mouse Heart and Suggest Cardiotoxicity From Combined Signal Transducer and Activator of Transcription and Epidermal Growth Factor Receptor Inhibition

BACKGROUND

Most novel cancer therapeutics target kinases that are essential to tumor survival. Some of these kinase inhibitors are associated with cardiotoxicity, whereas others appear to be cardiosafe. The basis for this distinction is unclear, as are the molecular effects of kinase inhibitors in the heart.

METHODS AND RESULTS

We administered clinically relevant doses of sorafenib, sunitinib (cardiotoxic multitargeted kinase inhibitors), or erlotinib (a cardiosafe epidermal growth factor receptor inhibitor) to mice daily for 2 weeks. We then compared the effects of these 3 kinase inhibitors on the cardiac transcriptome using RNAseq and the cardiac kinome using multiplexed inhibitor beads coupled with mass spectrometry. We found unexpectedly broad molecular effects of all 3 kinase inhibitors, suggesting that target kinase selectivity does not define either the molecular response or the potential for cardiotoxicity. Using in vivo drug administration and primary cardiomyocyte culture, we also show that the cardiosafety of erlotinib treatment may result from upregulation of the cardioprotective signal transducer and activator of transcription 3 pathway, as co-treatment with erlotinib and a signal transducer and activator of transcription inhibitor decreases cardiac contractile function and cardiomyocyte fatty acid oxidation.

CONCLUSIONS

Collectively our findings indicate that preclinical kinome and transcriptome profiling may predict the cardiotoxicity of novel kinase inhibitors, and suggest caution for the proposed therapeutic strategy of combined signal transducer and activator of transcription/epidermal growth factor receptor inhibition for cancer treatment.

Pterostilbene, a natural phenolic compound, synergizes the antineoplastic effects of megestrol acetate in endometrial cancer

Endometrial cancer is the most common gynecologic cancer in the United States and its incidence and mortality has been rising over the past decade. Few treatment options are available for patients with advanced and recurring endometrial cancers. Novel therapies, which are frequently toxic, are difficult to establish in this patient population which tends to be older and plagued by comorbidities such as diabetes mellitus and hypertension. Therefore, novel, non-toxic therapies are urgently needed. Megestrol acetate is a frequently used drug in endometrial cancer patients. However, its response rate is only 20–30%. To enhance the activity of megestrol acetate in endometrial cancer patients, we explored the potential of combining natural supplements with megestrol acetate and found that the addition of the natural phenolic compound, pterostilbene, to megestrol acetate resulted in a synergistic inhibition of cancer cell growth in vitro and an enhanced reduction of tumor growth in a xenograft mouse model. In addition, dual treatment led to attenuation of signaling pathways, as well as cell cycle and survival pathways. Our results demonstrated for the first time that the anti-tumor activity of megestrol acetate can be enhanced by combining with pterostilbene, providing an insight into the potential application of pterostilbene and megestrol acetate combination for the treatment of endometrial cancer.

Knockdown of long non-coding RNA MALAT1 inhibits growth and motility of human hepatoma cells via modulation of miR-195

The metastasis-associated lung adenocarcinoma transcription 1 (Malat1) is a long non-coding RNA (lncRNA), exerts oncogenic role in multiple cancers, including hepatocellular carcinoma (HCC). This study was aimed to investigate its posttranscriptional regulation in HCC cells. RT-PCR was performed to monitor the expression levels of Malat1 in normal liver and HCC cell lines. The expression of Malat1, microRNA (miR)-195, and epidermal growth factor receptor (EGFR) in HepG2 and MHCC97 cells was respectively or synchronously altered by transfection. Then the changes in cell viability, apoptotic cell rate, cell cycle distribution, migration, and invasion were respectively assessed. As a result, we found that Malat1 was highly expressed in HCC cell lines when compared to normal liver cells. Malat1 silence suppressed HCC cells viability, migration and invasion, induced apoptosis, and arrested more cells in G0/G1 phase. Malat1 acted as a circular endogenous RNA (ceRNA) for miR-195. Malat1 silence could not suppress HCC cell growth and motility when miR-195 was knocked down. EGFR was a direct target of miR-195. miR-195 overexpression could not suppress HCC cell growth and motility when the 3'UTR site of EGFR was overexpressed. Furthermore, Malat1 silence blocked the activation of PI3K/AKT and JAK/STAT pathways, while EGFR overexpression activated them. Our study demonstrates Malat1-miR-195-EGFR axis plays a critical role in HCC cells which provided a better understanding of Malat1 in HCC.