Targeting Notch signaling pathway to overcome drug resistance for cancer therapy

Analysis of the Differentially Expressed Genes Induced by Cisplatin Resistance in Oral Squamous Cell Carcinomas and Their Interaction

BACKGROUND

Oral squamous cell carcinoma (OSCC) is a solid tumor, which originates from squamous epithelium, with about 400,000 new-cases/year worldwidely. Presently, chemoradiotherapy is the most important adjuvant treatment for OSCC, mostly in advanced tumors. However, clinical resistance to chemotherapy still leads to poor prognosis of OSCC patients. Via high-throughput analysis of gene expression database of OSCC, we investigated the molecular mechanisms underlying cisplatin resistance in OSCC, analyzing the differentially expressed genes (DEGs) and their regulatory relationship, to clarify the molecular basis of OSCC chemotherapy resistance and provide a theoretical foundation for the treatment of patients with OSCC and individualized therapeutic targets accurately.

METHODS

Datasets related to "OSCC" and "cisplatin resistance" (GSE111585 and GSE115119) were downloaded from the GEO database and analyzed by GEO2R. Venn diagram was used to obtain drug-resistance-related DEGs. Functional enrichment analysis and Kyoto encyclopedia of genes and genomes (KEGG) pathway analysis were performed on DEGs using The Database for Annotation, Visualization and Integrated Discovery (DAVID) software. Protein-protein interaction (PPI) network was constructed by STRING (search tool for recurring instances of neighbouring genes) database. Potential target genes of miRNA were predicted via miRDB, and cBioportal was used to analyze the function and survival of the potential functional genes.

RESULTS

Forty-eight upregulated DEGs and 49 downregulated DEGs were obtained from the datasets, with cutoff as p < 0.01 and |log FC| > 1. The DEGs in OSCC mainly enriched in cell proliferation regulation, and chemokine activity. In PPI network with hub score > 300, the hub genes were identified as NOTCH1, JUN, CTNNB1, CEBPA, and ETS1. Among miRNA-mRNA targeting regulatory network, hsa-mir-200c-3p, hsa-mir-200b-3p, hsa-mir-429, and hsa-mir-139-5p were found to simultaneously regulate multiple hub genes. Survival analysis showed that patients with high CTNNB1 or low CEBPA expression had poor outcome.

CONCLUSIONS

In the OSCC cisplatin-resistant cell lines, NOTCH1, JUN, CTNNB1, CEBPA, and ETS1 were found as the hub genes involved in regulating the cisplatin resistance of OSCC. Members of the miR-200 family may reverse drug resistance of OSCC cells by regulating the hub genes, which can act as potential targets for the treatment of OSCC patients with cisplatin resistance.

The clinicopathologic significance of Notch3 expression in prostate cancer

The Notch3 signaling pathway plays an important role in oncogenesis, tumor maintenance, and resistance to chemotherapy in human cancers. However, its role in prostate cancer (PC) is less clear. In this study, we investigated a total of 142 PC patients who underwent radical prostatectomy and examined the expression of Notch3 in PC cells using immunohistochemistry on tissue microarrays and evaluated their clinicopathological significance. The overexpression of Notch3 was observed in 22 (15.5%) out of 142 PC cases. The overexpression of Notch3 was significantly associated with lymph node metastasis (P = 0.013), higher pT stages (P = 0.033), higher pathological tumor stages (P = 0.034), and higher grades groups (P = 0.025). However, the overexpression of Notch3 was not correlated with lympho-vascular invasion, neural invasion, extra-prostatic extension, or the serum prostate-specific antigen level. This study demonstrates that Notch3 plays an oncogenic function in PC and the overexpression of Notch3 is correlated with invasiveness, metastasis, and higher Gleason grades, reflecting the features of aggressive tumors in PC, and could be an important biomarker and a possible therapeutic target. Further studies evaluating the association between Notch3 expression and survival are required.

The basics of epithelial-mesenchymal transition (EMT): A study from a structure, dynamics, and functional perspective

Epithelial-mesenchymal transition (EMT) is a key step in transdifferentiation process in solid cancer development. Forthcoming evidence suggest that the stratified program transforms polarized, immotile epithelial cells to migratory mesenchymal cells associated with enhancement of breast cancer stemness, metastasis, and drug resistance. It involves primarily several signaling pathways, such as transforming growth factor-β (TGF-β), cadherin, notch, plasminogen activator protein inhibitor, urokinase plasminogen activator, and WNT/beta catenin pathways. However, current understanding on the crosstalk of multisignaling pathways and assemblies of key transcription factors remain to be explored. In this review, we focus on the crosstalk of signal transduction pathways linked to the current therapeutic and drug development strategies. We have also performed the computational modeling on indepth the structure and conformational dynamic studies of regulatory proteins and analyze molecular interactions with their associate factors to understand the complicated process of EMT in breast cancer progression and metastasis. Electrostatic potential surfaces have been analyzed that help in optimization of electrostatic interactions between the protein and its ligand. Therefore, understanding the biological implications underlying the EMT process through molecular biology with biocomputation and structural biology approaches will enable the development of new therapeutic strategies to sensitize tumors to conventional therapy and suppress their metastatic phenotype.

LINC00957 Acted as Prognostic Marker Was Associated With Fluorouracil Resistance in Human Colorectal Cancer

Colorectal cancer (CRC) is one of the most prevalent digestive tumors in China. Recent studies indicate that long intergenic non-coding RNAs (lincRNAs) play a crucial role in predicting survival for CRC patients. However, the novel lincRNA, LINC00957, is largely unclear in CRC. The purpose of the current study was to determine LINC00957 expression, assess its the clinical significance and explore the potential mechanism in CRC. The qRT-PCR was used to quantify the expression levels of LINC00957 in tissues and cell lines. Our research revealed that LINC00957 was significantly higher expression in CRC. In addition, the LINC00957 expression was associated with TNM stage and chemotherapy outcome, but age, gender, tumor size, histological grade, primary tumor location. CRC patients with high LINC00957 expression level showed poor overall survival (P = 0.002). Multivariate survival analysis indicated that LINC00957 was a prognostic factor for CRC patients (P = 0.010). Mechanically, inhibition of LINC00957 expression reversed 5-FU resistance by down-regulating P-gP. In summary, our study indicated that this novel lncRNA expression signature might be a useful biomarker of the prognosis and therapeutic target for CRC patients.

CTAB Enhances Chemo-Sensitivity Through Activation of AMPK Signaling Cascades in Breast Cancer

Metabolic reprogramming is thought to be one of the initiators in cancer drug resistance. It has been shown that CTAB is capable of interfering the efficiency of cancer therapy by regulation of cell metabolic reprogramming. In this study, we hypothesized that AMPK as a key metabolic regulator plays a crucial role in regulation of breast cancer drug resistance, which could be alleviated by treatment of CTAB. We observed that CTAB can improve the DOX sensitivity of the breast cancer cells by inhibition of the ATP-dependent drug-efflux pump P-gp complex through activation of the AMPK-HIF-1α-P-gp cascades. The CTAB effect was also confirmed in vivo showing low systemic toxicity. Taken together, our results showed that CTAB sensitized drug resistance of breast cancer to DOX chemotherapy by activating AMPK signaling cascades both in vitro and in vivo, suggested that CTAB may be developed as a promising and novel chemosensitizer and chemotherapeutic candidate for breast cancer treatment.

Cell signaling and cancer: a mechanistic insight into drug resistance

Drug resistance is a major setback for advanced therapeutics in multiple cancers. The increasing prevalence of this resistance is a growing concern and bitter headache for the researchers since a decade. Hence, it is essential to revalidate the existing strategies available for cancer treatment and to look after a novel therapeutic approach for target based killing of cancer cells at the genetic level. This review outlines the different mechanisms enabling resistance including drug efflux, drug target alternation, alternative splicing, the release of the extracellular vesicle, tumor heterogeneity, epithelial-mesenchymal transition, tumor microenvironment, the secondary mutation in the receptor, epigenetic alternation, heterodimerization of receptors, amplification of target and amplification of components rather than the target. Furthermore, existing evidence and the role of various signaling pathways like EGFR, Ras, PI3K/Akt, Wnt, Notch, TGF-β, Integrin-ECM signaling in drug resistance are explained. Lastly, the prevention of this resistance by a contemporary therapeutic strategy, i.e., a combination of specific signaling pathway inhibitors and the cocktail of a cancer drug is summarized showing the new treatment strategies.

Knockdown of MAML1 inhibits proliferation and induces apoptosis of T-cell acute lymphoblastic leukemia cells through SP1-dependent inactivation of TRIM59

Notch exerts important functions in cell proliferation, survival, and differentiation, which plays a critical role in tumor development when aberrantly activated. Mastermind-like protein 1 (MAML1) has been functioning as crucial coactivators of Notch receptors and is required for stable formation of Notch transcriptional complexes. However, the mechanism whereby MAML1 induces T-cell acute lymphoblastic leukemia (T-ALL) tumorigenesis is largely unknown. The CCK-8 and flow cytometry assay were performed to examine the effect of MAML1 knockdown on T-ALL cell proliferation, apoptosis, and cell cycle. The expression of MAML1, cell cycle, and apoptosis-related gene, as well as TRIM family members and specific protein 1 (SP1) was measured by western blot analysis and qPCR. Our results showed that MAML1 knockdown significantly inhibited cell proliferation and induced G0/G1 cell cycle arrest and apoptosis in Jurkat and MOLT-4 cells. Cell cycle and apoptosis-related gene expression, including CDK2, Bcl-2, Bax, and Bad, was modified by the MAML1 knockdown. MAML1 knockdown obviously inhibited the CDK2 and Bcl-2 expression and increased the Bax, p53, and Bad expression. Moreover, the TRIM family members, including TRIM13, TRIM32, TRIM44, and TRIM59, were significantly decreased by the MAML1 knockdown, with the highest decrease detected in TRIM59 expression. Interesting, overexpression of SP1 not only increased the expression of MAML1 and TRIM59, but also promoted the promoter activation of TRIM59. Taken together, knockdown of MAML1 inhibits proliferation and induces apoptosis of T-ALL cells through SP1-dependent inactivation of TRIM59, and therefore suggest that MAML1-SP1-TRIM59 axis may serve as potentially interesting therapeutic targets for treatment of T-ALL.

A novel triazole, NMK-T-057, induces autophagic cell death in breast cancer cells by inhibiting γ-secretase-mediated activation of Notch signaling

Notch signaling is reported to be deregulated in several malignancies, including breast, and the enzyme γ-secretase plays an important role in the activation and nuclear translocation of Notch intracellular domain (NICD). Hence, pharmacological inhibition of γ-secretase might lead to the subsequent inhibition of Notch signaling in cancer cells. In search of novel γ-secretase inhibitors (GSIs), we screened a series of triazole-based compounds for their potential to bind γ-secretase and observed that 3-(3'4',5'-trimethoxyphenyl)-5-(N-methyl-3'-indolyl)-1,2,4-triazole compound (also known as NMK-T-057) can bind to γ-secretase complex. Very interestingly, NMK-T-057 was found to inhibit proliferation, colony-forming ability, and motility in various breast cancer (BC) cells such as MDA-MB-231, MDA-MB-468, 4T1 (triple-negative cells), and MCF-7 (estrogen receptor (ER)/progesterone receptor (PR)-positive cell line) with negligible cytotoxicity against noncancerous cells (MCF-10A and peripheral blood mononuclear cells). Furthermore, significant induction of apoptosis and inhibition of epithelial-to-mesenchymal transition (EMT) and stemness were also observed in NMK-T-057-treated BC cells. The in silico study revealing the affinity of NMK-T-057 toward γ-secretase was further validated by a fluorescence-based γ-secretase activity assay, which confirmed inhibition of γ-secretase activity in NMK-T-057-treated BC cells. Interestingly, it was observed that NMK-T-057 induced significant autophagic responses in BC cells, which led to apoptosis. Moreover, NMK-T-057 was found to inhibit tumor progression in a 4T1-BALB/c mouse model. Hence, it may be concluded that NMK-T-057 could be a potential drug candidate against BC that can trigger autophagy-mediated cell death by inhibiting γ-secretase-mediated activation of Notch signaling.

CD26/DPP4 - a potential biomarker and target for cancer therapy

CD26/dipeptidyl peptidase (DPP)4 is a membrane-bound protein found in many cell types of the body, and a soluble form is present in body fluids. There is longstanding evidence that various primary tumors and also metastases express CD26/DPP4 to a variable extent. By cleaving dipeptides from peptides with a proline or alanine in the penultimate position at the N-terminus, it regulates the activity of incretin hormones, chemokines and many other peptides. Due to these effects and interactions with other molecules, a tumor promoting or suppressing role can be attributed to CD26/DPP4. In this review, we discuss the existing evidence on the expression of soluble or membrane-bound CD26/DPP4 in malignant diseases, along with the most recent findings on CD26/DPP4 as a therapeutic target in specific malignancies. The expression and possible involvement of the related DPP8 and DPP9 in cancer are also reviewed. A higher expression of CD26/DPP4 is found in a wide variety of tumor entities, however more research on CD26/DPP4 in the tumor microenvironment is needed to fully explore its use as a tumor biomarker. Circulating soluble CD26/DPP4 has also been studied as a cancer biomarker, however, the observed decrease in most cancer patients does not seem to be cancer specific. Encouraging results from experimental work and a recently reported first phase clinical trial targeting CD26/DPP4 in mesothelioma, renal and urological tumors pave the way for follow-up clinical studies, also in other tumor entities, possibly leading to the development of more effective complementary therapies against cancer.

Gemcitabine induces Epithelial-to-Mesenchymal Transition in patient-derived pancreatic ductal adenocarcinoma xenografts

There is a lack of well-characterized models for pancreatic ductal adenocarcinoma (PDAC). PDAC itself is unique because of its pronounced tumor microenvironment that influences tumor progression, behavior and therapeutic resistance. Here we investigated, in patient-derived tumor xenograft (PDTX) models developed from fine needle biopsies, the cancer cells behavior, Epithelial-to-Mesenchymal Transition (EMT) and drug response. For this, we studied two behaviorally distinct PDTX models. Tumor volume measurement, histology, immuno-histochemical staining, RT-qPCR, RNA sequencing and Western blotting were used to further characterize these models and investigate the effect of two classes of drugs (gemcitabine and acriflavine (HIF-inhibitor)). The models recapitulated the corresponding primary tumors. The growth-rate of the poorly differentiated tumor (PAC010) was faster than that of the moderately differentiated tumor (PAC006) (P<0.05). The PAC010 model showed increased cell proliferation (Ki-67 staining) and markers indicating survival (increased p-AKT, p-ERK and p-NF-kB65 and suppression of cleaved PARP). Gene and protein analysis showed higher expression of mesenchymal markers in PAC010 model (e.g. VIM, SNAI2). Pathway analysis demonstrated activation of processes related to EMT, tumor progression and aggressiveness in PAC010. Gemcitabine treatment resulted in shrinking of the tumor volume and reduced proliferation in both models. Importantly, gemcitabine treatment significantly enhanced the expression of mesenchymal marker supportive of metastatic behavior and of survival pathways, particularly in the non-aggressive PAC006 model. Acriflavine had little effect on tumor growth in both models. In conclusion, we observed in this unique model of PDAC, a clear link between EMT and poor tumor differentiation and found that gemcitabine can increase EMT.

Traditional Chinese medicine as targeted treatment for epithelial-mesenchymal transition-induced cancer progression

The epithelial-mesenchymal transition (EMT) program, which loosens cell-cell adhesion complexes, endows cells with enhanced migratory and invasive properties. Furthermore, this process facilitates both the development of drug resistance and immunosuppression by tumor cells, which preclude the successful treatment of cancer. Recent research has demonstrated that many signaling pathways are involved in EMT progression. In addition, cancer stem cells (CSCs), vasculogenic mimicry (VM) and the tumor-related immune microenvironment all play important roles in tumor formation. However, there are few reports on the relationships between EMT and these factors. In addition, in recent years, traditional Chinese medicine (TCM) has developed a unique system for treating cancer. In this review, we summarize the crucial signaling pathways associated with the EMT process in cancer patients and discuss the interconnections between EMT and other molecular factors (such as CSCs, VM, and the tumor-related immune microenvironment). We attempt to identify common regulators that might be potential therapeutic targets to thereby optimize tumor treatment. In addition, we outline recent research on TCM approaches that target EMT and thereby provide a foundation for further research on the exact mechanisms by which TCMs affect EMT in cancer.

Possible role of Porphyromonas gingivalis in orodigestive cancers

There is increasing evidence for an association between periodontitis/tooth loss and oral, gastrointestinal, and pancreatic cancers. Periodontal disease, which is characterized by chronic inflammation and microbial dysbiosis, is a significant risk factor for orodigestive carcinogenesis. Porphyromonas gingivalis is proposed as a keystone pathogen in chronic periodontitis causing both dysbiosis and discordant immune response. The present review focuses on the growing recognition of a relationship between P. gingivalis and orodigestive cancers. Porphyromonas gingivalis has been recovered in abundance from oral squamous cell carcinoma (OSCC). Recently established tumorigenesis models have indicated a direct relationship between P. gingivalis and carcinogenesis. The bacterium upregulates specific receptors on OSCC cells and keratinocytes, induces epithelial-to-mesenchymal (EMT) transition of normal oral epithelial cells and activates metalloproteinase-9 and interleukin-8 in cultures of the carcinoma cells. In addition, P. gingivalis accelerates cell cycling and suppresses apoptosis in cultures of primary oral epithelial cells. In oral cancer cells, the cell cycle is arrested and there is no effect on apoptosis, but macro autophagy is increased. Porphyromonas gingivalis promotes distant metastasis and chemoresistance to anti-cancer agents and accelerates proliferation of oral tumor cells by affecting gene expression of defensins, by peptidyl-arginine deiminase and noncanonical activation of β-catenin. The pathogen also converts ethanol to the carcinogenic intermediate acetaldehyde. In addition, P. gingivalis can be implicated in precancerous gastric and colon lesions, esophageal squamous cell carcinoma, head and neck (larynx, throat, lip, mouth and salivary glands) carcinoma, and pancreatic cancer. The fact that distant organs can be involved clearly emphasizes that P. gingivalis has systemic tumorigenic effects in addition to the local effects in its native territory, the oral cavity. Although coinfection with other bacteria, viruses, and fungi occurs in periodontitis, P. gingivalis relates to cancer even in absence of periodontitis. Thus, there may be a direct relationship between P. gingivalis and orodigestive cancers.

Moving Breast Cancer Therapy up a Notch

Breast cancer is the second most common malignancy, worldwide. Treatment decisions are based on tumor stage, histological subtype, and receptor expression and include combinations of surgery, radiotherapy, and systemic treatment. These, together with earlier diagnosis, have resulted in increased survival. However, initial treatment efficacy cannot be guaranteed upfront, and these treatments may come with (long-term) serious adverse effects, negatively affecting a patient's quality of life. Gene expression-based tests can accurately estimate the risk of recurrence in early stage breast cancers. Disease recurrence correlates with treatment resistance, creating a major need to resensitize tumors to treatment. Notch signaling is frequently deregulated in cancer and is involved in treatment resistance. Preclinical research has already identified many combinatory therapeutic options where Notch involvement enhances the effectiveness of radiotherapy, chemotherapy or targeted therapies for breast cancer. However, the benefit of targeting Notch has remained clinically inconclusive. In this review, we summarize the current knowledge on targeting the Notch pathway to enhance current treatments for breast cancer and to combat treatment resistance. Furthermore, we propose mechanisms to further exploit Notch-based therapeutics in the treatment of breast cancer.

Nano-Mediated Photodynamic Therapy for Cancer: Enhancement of Cancer Specificity and Therapeutic Effects

Deregulation of cell growth and development lead to cancer, a severe condition that claims millions of lives worldwide. Targeted or selective approaches used during cancer treatment determine the efficacy and outcome of the therapy. In order to enhance specificity and targeting and obtain better treatment options for cancer, novel modalities are currently under development. Photodynamic therapy has the potential to eradicate cancer, and combination therapy would yield even greater outcomes. Nanomedicine-aided cancer therapy shows enhanced specificity for cancer cells and minimal side-effects coupled with effective cancer destruction both in vitro and in vivo. Nanocarriers used in drug-delivery systems are very capable of penetrating the cancer stem cell niche, simultaneously killing cancer cells and eradicating drug-resistant cancer stem cells, yielding therapeutic efficiency of up to 100-fold against drug-resistant cancer in comparison with free drugs. Safety precautions should be considered when using nano-mediated therapy as the effects of extended exposure to biological environments are still to be determined.

γ-secretase inhibitor DAPT mitigates cisplatin-induced acute kidney injury by suppressing Notch1 signaling

Organ toxicity, including kidney injury, limits the use of cisplatin for the treatment of multiple human cancers. Hence, interventions to alleviate cisplatin-induced nephropathy are of benefit to cancer patients. Recent studies have demonstrated that pharmacological inhibition of the Notch signaling pathway enhances cisplatin efficacy against several cancer cells. However, whether augmentation of the anti-cancer effect of cisplatin by Notch inhibition comes at the cost of increased kidney injury is unclear. We show here that treatment of mice with cisplatin resulted in a significant increase in Notch ligand Delta-like 1 (Dll1) and Notch1 intracellular domain (N1ICD) protein expression levels in the kidneys. N-[N-(3,5-difluorophenacetyl)-L-alanyl]-S-phenylglycine t-butyl ester (DAPT), a γ-secretase inhibitor reversed cisplatin-induced increase in renal N1ICD expression and plasma or urinary levels of predictive biomarkers of acute kidney injury (AKI). DAPT also mitigated cisplatin-induced tubular injury and reduction in glomerular filtration rate. Real-time multiphoton microscopy revealed marked necrosis and peritubular vascular dysfunction in the kidneys of cisplatin-treated mice which were abrogated by DAPT. Cisplatin-induced Dll1/Notch1 signaling was recapitulated in a human proximal tubule epithelial cell line (HK-2). siRNA-mediated Dll1 knockdown and DAPT attenuated cisplatin-induced Notch1 cleavage and cytotoxicity in HK-2 cells. These data suggest that Dll1-mediated Notch1 signaling contributes to cisplatin-induced AKI. Hence, the Notch signaling pathway could be a potential therapeutic target to alleviate renal complications associated with cisplatin chemotherapy.

Exploring major signaling cascades in melanomagenesis: a rationale route for targetted skin cancer therapy

Although most melanoma cases may be treated by surgical intervention upon early diagnosis, a significant portion of patients can still be refractory, presenting low survival rates within 5 years after the discovery of the illness. As a hallmark, melanomas are highly prone to evolve into metastatic sites. Moreover, melanoma tumors are highly resistant to most available drug therapies and their incidence have increased over the years, therefore leading to public health concerns about the development of novel therapies. Therefore, researches are getting deeper in unveiling the mechanisms by which melanoma initiation can be triggered and sustained. In this context, important progress has been achieved regarding the roles and the impact of cellular signaling pathways in melanoma. This knowledge has provided tools for the development of therapies based on the intervention of signal(s) promoted by these cascades. In this review, we summarize the importance of major signaling pathways (mitogen-activated protein kinase (MAPK), phosphoinositide 3-kinase (PI3K)-Akt, Wnt, nuclear factor κ-light-chain-enhancer of activated B cell (NF-κB), Janus kinase (JAK)-signal transducer and activator of transcription (STAT), transforming growth factor β (TGF-β) and Notch) in skin homeostasis and melanoma progression. Available and developing melanoma therapies interfering with these signaling cascades are further discussed.

A novel inhibitor of ADAM17 sensitizes colorectal cancer cells to 5-Fluorouracil by reversing Notch and epithelial-mesenchymal transition in vitro and in vivo

OBJECTIVES

Colorectal cancer is one of the most common malignancies both in men and women. Owing to metastasis and resistance, the prognosis of colorectal cancerCRC patients remains extremely poor with chemotherapy. A disintegrin and metalloproteinase 17 (ADAM17) induces the activation of Notch pathway and contributes to the chemoresistance. This study aimed to discover a novel ADAM17 inhibitor and investigate the chemosensitization effect.

MATERIALS AND METHODS

Pharmacophore model, western blot and enzymatic assay were used to discover ZLDI-8. Cell proliferation was determined by MTT and colony formation assay. Cell migratory and invasive ability were determined by wound healing scratch and transwell assay. Immunofluorescence images and western blot analysed the expression of Notch or epithelial-mesenchymal transition (EMT) pathway markers. Xenografts were employed to evaluate the chemosensitization effect of ZLDI-8 in vivo.

RESULTS

We found that ZLDI-8 cell-specifically inhibited the proliferation of CRC, and this effect was due to abrogation of ADAM17 and Notch pathway. Meanwhile, we reported for the first time that ZLDI-8 synergistically improved the anti-tumour and anti-metastasis activity of 5-fluorouracil or irinotecan by reversing Notch and EMT pathways. Interestingly, in vivo studies further demonstrated that ZLDI-8 promoted the anti-tumour effect of 5-fluorouracil through Notch and EMT reversal.

CONCLUSIONS

A novel ADAM17 inhibitor ZLDI-8 may be a potential chemosensitizer which sensitized CRC cells to 5-fluorouracil or irinotecan by reversing Notch and EMT pathways.

Differential Expression and Pathway Analysis in Drug-Resistant Triple-Negative Breast Cancer Cell Lines Using RNASeq Analysis

Triple-negative breast cancer (TNBC) is among the most notorious types of breast cancer, the treatment of which does not give consistent results due to the absence of the three receptors (estrogen receptor (ER), progesterone receptor (PR), and human epidermal growth factor receptor 2 (HER2) as well as high amount of molecular variability. Drug resistance also contributes to treatment unresponsiveness. We studied differentially expressed genes, their biological roles, as well as pathways from RNA-Seq datasets of two different TNBC drug-resistant cell lines of Basal B subtype SUM159 and MDA-MB-231 treated with drugs JQ1 and Dexamethasone, respectively, to elucidate the mechanism of drug resistance. RNA sequencing(RNA-Seq) data analysis was done using edgeR which is an efficient program for determining the most significant Differentially Expressed Genes (DEGs), Gene Ontology (GO) terms, and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways. iPathway analysis was further used to obtain validated results using analysis that takes into consideration type, function, and interactions of genes in the pathway. The significant similarities and differences throw light into the molecular heterogeneity of TNBC, giving clues into the aspects that can be focused to overcome drug resistance. From this study, cytokine-cytokine receptor interaction pathway appeared to be a key factor in TNBC drug resistance.

Cervical Cancer Cell Growth, Drug Resistance, and Epithelial-Mesenchymal Transition Are Suppressed by y-Secretase Inhibitor RO4929097

BACKGROUND The Notch signaling pathway has been reported to play a pivotal role in tumorigenesis. Emerging evidence has demonstrated that the Notch signaling pathway regulates several cellular processes. The present study investigated the effect of the Notch signaling pathway on cell growth, invasiveness, and drug resistance, as well as epithelial-mesenchymal transition (EMT), of cervical cancer cells. MATERIAL AND METHODS We used quantitative real-time polymerase chain reaction (qRT-PCR) and Western blot analysis to measure the expression level of Notch2. CCK-8, clonality, wound healing, and Transwell assays were used to evaluate the effect of γ-secretase inhibitor (GSI) RO4929097 on cervical cancer cell lines HeLa and Caski. To explore the role of the Notch signaling pathway in EMT, the epithelial and mesenchymal markers were detected by qRT-PCR and Western blot after cervical cancer cell lines were treated with GSI RO4929097. RESULTS The expression of Notch2 was found to increase in cervical cancer cell lines compared with the normal immortalized human cervical epithelial cells. GSI RO4929097 was confirmed to inhibit the Notch signaling pathway and impaired the proliferation, drug resistance, migration, and invasion abilities of cervical cancer cells. The protein expression levels of the mesenchymal biomarkers Snail, Twist, and neural cadherin (N-cadherin) decreased; however, the expression of the epithelial biomarker epithelial cadherin (E-cadherin) increased in the cervical cancer cells treated with GSI RO4929097. CONCLUSIONS Notch signaling pathway plays an important role in the development and progression of cervical cancer. Blockade of the Notch pathway using GSI RO4929097 inhibited cell growth and reduced chemoresistance, invasion, metastasis, and EMT in cervical cancer cells.

MiR-92a Inhibits the Progress of Osteosarcoma Cells and Increases the Cisplatin Sensitivity by Targeting Notch1

Background

MicroRNAs (miRs) have been implicated in the development and progression of osteosarcoma. Here, we aimed to illustrate the important role of miR-92a on the regulation of OS development which may help to establish a novel strategy for OS diagnosis and treatment.

Materials and Methods

Cell viability was measured by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. Cell cycle and apoptosis were assessed by flow cytometry with PI and PI/Annexin-V stain, respectively. The expression of proteins was examined by western blot. qPCR was used to detect the expression of RNA. Cell migration was assayed with transwell assay.

Results

MiR-92a inhibited the proliferation and the migration of OS in vitro and reduced the volume of the tumour in vivo. Further, miR-92a enhanced cisplatin sensitivity of OS. MiR-92a directly targeted Notch1.

Conclusion

Together, our results indicate that miR-92a inhibited cell growth, migration, and enhanced cisplatin sensitivity of OS cell by targeting Notch1.

NOTCH3 inactivation increases triple negative breast cancer sensitivity to gefitinib by promoting EGFR tyrosine dephosphorylation and its intracellular arrest

Notch dysregulation has been implicated in numerous tumors, including triple-negative breast cancer (TNBC), which is the breast cancer subtype with the worst clinical outcome. However, the importance of individual receptors in TNBC and their specific mechanism of action remain to be elucidated, even if recent findings suggested a specific role of activated-Notch3 in a subset of TNBCs. Epidermal growth factor receptor (EGFR) is overexpressed in TNBCs but the use of anti-EGFR agents (including tyrosine kinase inhibitors, TKIs) has not been approved for the treatment of these patients, as clinical trials have shown disappointing results. Resistance to EGFR blockers is commonly reported. Here we show that Notch3-specific inhibition increases TNBC sensitivity to the TKI-gefitinib in TNBC-resistant cells. Mechanistically, we demonstrate that Notch3 is able to regulate the activated EGFR membrane localization into lipid rafts microdomains, as Notch3 inhibition, such as rafts depletion, induces the EGFR internalization and its intracellular arrest, without involving receptor degradation. Interestingly, these events are associated with the EGFR tyrosine dephosphorylation at Y1173 residue (but not at Y1068) by the protein tyrosine phosphatase H1 (PTPH1), thus suggesting its possible involvement in the observed Notch3-dependent TNBC sensitivity response to gefitinib. Consistent with this notion, a nuclear localization defect of phospho-EGFR is observed after combined blockade of EGFR and Notch3, which results in a decreased TNBC cell survival. Notably, we observed a significant correlation between EGFR and NOTCH3 expression levels by in silico gene expression and immunohistochemical analysis of human TNBC primary samples. Our findings strongly suggest that combined therapies of TKI-gefitinib with Notch3-specific suppression may be exploited as a drug combination advantage in TNBC treatment.

Oral cancer cells sustainedly infected with Porphyromonas gingivalis exhibit resistance to Taxol and have higher metastatic potential

Major obstacles to improving the prognosis of patients with oral squamous cell carcinoma (OSCC) are the acquisition of resistance to chemotherapeutic agents and development of metastases. Recently, inflammatory signals are suggested to be one of the most important factors in modulating chemoresistance and establishing metastatic lesions. In addition, epidemiological studies have demonstrated that periodontitis, the most common chronic inflammatory condition of the oral cavity, is closely associated with oral cancer. However, a correlation between chronic periodontitis and chemoresistance/metastasis has not been well established. Herein, we will present our study on whether sustained infection with Porphyromonas gingivalis, a major pathogen of chronic periodontitis, could modify the response of OSCC cells to chemotherapeutic agents and their metastatic capability in vivo. Tumor xenografts composed of P. gingivalis–infected OSCC cells demonstrated a higher resistance to Taxol through Notch1 activation, as compared with uninfected cells. Furthermore, P. gingivalis–infected OSCC cells formed more metastatic foci in the lung than uninfected cells.

Leptin-Notch axis impairs 5-fluorouracil effects on pancreatic cancer

5-FU chemotherapy is a current strategy to treat pancreatic cancer (PC), but unfortunately chemoresistance is eventually developed in most patients. Obesity is a risk factor for PC that could affect 5-FU effectiveness through the adipokine leptin, which is a known proliferation, survival factor and Notch inducer. We investigated whether leptin signaling affects 5-FU cytotoxicity on PC. To this end, tumorspheres developed from BxPC-3 and MiaPaCa-2 PC cells were treated with 5-FU, leptin, inhibitors for Notch (DAPT) and leptin signaling (IONP-LPrA2) and ATP-binding cassette of proteins (Probenecid). Leptin treatment decreased 5-FU cytotoxicity, and increased cell proliferation, colony forming ability, stem cell, pluripotency, EMT markers, drug efflux proteins (ABCC5, ABCC11) and Notch. In addition, leptin reduced the 5-FU effects on apoptosis by decreasing pro-apoptotic (Bax, Caspase-3 activation and PARP degradation) and increasing anti-apoptotic factors (RIP and Bcl-XL). Leptin's effects on PC tumorspheres treated with 5-FU were reduced by IONP-LPrA2 and were mainly Notch signaling- dependent and more evident in MiaPaCa-2-derived tumorspheres. Present results suggest that leptin could impair 5-FU cytotoxicity and promote chemoresistance. Therefore, targeting the leptin-Notch axis could be a novel way to improve 5-FU therapy for PC patients, especially in obesity context.

Regulation of Cell Signaling Pathways and miRNAs by Resveratrol in Different Cancers

Genomic and proteomic studies have helped improve our understanding of the underlying mechanism(s) of cancer development and progression. Mutations, overexpressed oncogenes, inactivated/downregulated tumor suppressors, loss of apoptosis, and dysregulated signal transduction cascades are some of the well-studied areas of research. Resveratrol has gained considerable attention in the last two decades because of its pleiotropic anticancer activities. In this review, we have summarized the regulation of WNT, SHH (sonic hedgehog)/GLI (glioma-associated oncogene homolog), TGFβ1 (transforming growth factor beta 1)/SMAD, NOTCH, TRAIL (tumor necrosis factor-related apoptosis-inducing ligand), STAT (signal transducer and activator of transcription), and microRNAs by resveratrol in different cancers. The importance of these signaling pathways in cancer progression, along with their modulation by resveratrol, is discussed. Further, we also evaluate the mechanisms and implications of the downregulation of oncogenic miRNAs and the upregulation of tumor suppressor miRNAs by resveratrol, both of which also define its ability to inhibit tumor growth and metastasis. It is envisioned that designing effective clinical trials will be helpful for the identification of resveratrol responders and non-responders and the elucidation of how this phytochemical can be combined with current therapeutic options to improve their clinical efficacy and reduce off-target effects.

Leptin-Notch signaling axis is involved in pancreatic cancer progression

Pancreatic cancer (PC) shows a high death rate. PC incidence and prognosis are affected by obesity, a pandemic characterized by high levels of leptin. Notch is upregulated by leptin in breast cancer. Thus, leptin and Notch crosstalk could influence PC progression. Here we investigated in PC cell lines (BxPC-3, MiaPaCa-2, Panc-1, AsPC-1), derived tumorspheres and xenografts whether a functional leptin-Notch axis affects PC progression and expansion of pancreatic cancer stem cells (PCSC). PC cells and tumorspheres were treated with leptin and inhibitors of Notch (gamma-secretase inhibitor, DAPT) and leptin (iron oxide nanoparticle-leptin peptide receptor antagonist 2, IONP-LPrA2). Leptin treatment increased cell cycle progression and proliferation, and the expression of Notch receptors, ligands and targeted molecules (Notch1-4, DLL4, JAG1, Survivin and Hey2), PCSC markers (CD24/CD44/ESA, ALDH, CD133, Oct-4), ABCB1 protein, as well as tumorsphere formation. Leptin-induced effects on PC and tumorspheres were decreased by IONP-LPrA2 and DAPT. PC cells secreted leptin and expressed the leptin receptor, OB-R, which indicates a leptin autocrine/paracrine signaling loop could also affect tumor progression. IONP-LPrA2 treatment delayed the onset of MiaPaCa-2 xenografts, and decreased tumor growth and the expression of proliferation and PCSC markers. Present data suggest that leptin-Notch axis is involved in PC. PC has no targeted therapy and is mainly treated with chemotherapy, whose efficiency could be decreased by leptin and Notch activities. Thus, the leptin-Notch axis could be a novel therapeutic target, particularly for obese PC patients.

Targeting Notch enhances the efficacy of ERK inhibitors in BRAF-V600E melanoma

The discovery of activating BRAF mutations in approximately 50% of melanomas has led to the development of MAPK pathway inhibitors, which have transformed melanoma therapy. However, not all BRAF-V600E melanomas respond to MAPK inhibition. Therefore, it is important to understand why tumors with the same oncogenic driver have variable responses to MAPK inhibitors. Here, we show that concurrent loss of PTEN and activation of the Notch pathway is associated with poor response to the ERK inhibitor SCH772984, and that co-inhibition of Notch and ERK decreased viability in BRAF-V600E melanomas. Additionally, patients with low PTEN and Notch activation had significantly shorter progression free survival when treated with BRAF inhibitors. Our studies provide a rationale to further develop combination strategies with Notch antagonists to maximize the efficacy of MAPK inhibition in melanoma. Our findings should prompt the evaluation of combinations co-targeting MAPK/ERK and Notch as a strategy to improve current therapies and warrant further evaluation of co-occurrence of aberrant PTEN and Notch activation as predictive markers of response to therapy.

Transcriptional profiling of NCI/ADR-RES cells unveils a complex network of signaling pathways and molecular mechanisms of drug resistance

Background

Ovarian cancer has the highest mortality rate among all the gynecological cancers. This is mostly due to the resistance of ovarian cancer to current chemotherapy regimens. Therefore, it is of crucial importance to identify the molecular mechanisms associated with chemoresistance.

Methods

NCI/ADR-RES is a multidrug-resistant cell line that is a model for the study of drug resistance in ovarian cancer. We carried out a microarray-derived transcriptional profiling analysis of NCI/ADR-RES to identify differentially expressed genes relative to its parental OVCAR-8.

Results

Gene-expression profiling has allowed the identification of genes and pathways that may be important for the development of drug resistance in ovarian cancer. The NCI/ADR-RES cell line has differential expression of genes involved in drug extrusion, inactivation, and efficacy, as well as genes involved in the architectural and functional reorganization of the extracellular matrix. These genes are controlled through different signaling pathways, including MAPK–Akt, Wnt, and Notch.

Conclusion

Our findings highlight the importance of using orthogonal therapies that target completely independent pathways to overcome mechanisms of resistance to both classical chemotherapeutic agents and molecularly targeted drugs.

Co-targeting of Tiam1/Rac1 and Notch ameliorates chemoresistance against doxorubicin in a biomimetic 3D lymphoma model

Lymphoma is a heterogeneous disease with a highly variable clinical course and prognosis. Improving the prognosis for patients with relapsed and treatment-resistant lymphoma remains challenging. Current in vitro drug testing models based on 2D cell culture lack natural tissue-like structural organization and result in disappointing clinical outcomes. The development of efficient drug testing models using 3D cell culture that more accurately reflects in vivo behaviors is vital. Our aim was to establish an in vitro 3D lymphoma model that can imitate the in vivo 3D lymphoma microenvironment. Using this model, we explored strategies to enhance chemosensitivity to doxorubicin, an important chemotherapeutic drug widely used for the treatment of hematological malignancies. Lymphoma cells grown in this model exhibited excellent biomimetic properties compared to conventional 2D culture including (1) enhanced chemotherapy resistance, (2) suppressed rate of apoptosis, (3) upregulated expression of drug resistance genes (MDR1, MRP1, BCRP and HIF-1α), (4) elevated levels of tumor aggressiveness factors including Notch (Notch-1, -2, -3, and -4) and its downstream molecules (Hes-1 and Hey-1), VEGF and MMPs (MMP-2 and MMP-9), and (5) enrichment of a lymphoma stem cell population. Tiam1, a potential biomarker of tumor progression, metastasis, and chemoresistance, was activated in our 3D lymphoma model. Remarkably, we identified two synergistic therapeutic oncotargets, Tiam1 and Notch, as a strategy to combat resistance against doxorubicin in EL4 T and A20 B lymphoma. Therefore, our data suggest that our 3D lymphoma model is a promising in vitro research platform for studying lymphoma biology and therapeutic approaches.

Left-right analysis of mammary gland development in retinoid X receptor-α+/- mice

Left-right (L-R) differences in mammographic parenchymal patterns are an early predictor of breast cancer risk; however, the basis for this asymmetry is unknown. Here, we use retinoid X receptor alpha heterozygous null (RXRα^+/-) mice to propose a developmental origin: perturbation of coordinated anterior-posterior (A-P) and L-R axial body patterning. We hypothesized that by analogy to somitogenesis-in which retinoic acid (RA) attenuation causes anterior somite pairs to develop L-R asynchronously-that RA pathway perturbation would likewise result in asymmetric mammary development. To test this, mammary glands of RXRα^+/- mice were quantitatively assessed to compare left- versus right-side ductal epithelial networks. Unlike wild-type controls, half of the RXRα^+/- thoracic mammary gland (TMG) pairs exhibited significant L-R asymmetry, with left-side reduction in network size. In RXRα^+/- TMGs in which symmetry was maintained, networks had bilaterally increased size, with left networks showing greater variability in area and pattern. Reminiscent of posterior somites, whose bilateral symmetry is refractory to RA attenuation, inguinal mammary glands (IMGs) also had bilaterally increased network size, but no loss of symmetry. Together, these results demonstrate that mammary glands exhibit differential A-P sensitivity to RXRα heterozygosity, with ductal network symmetry markedly compromised in anterior but not posterior glands. As TMGs more closely model human breast development than IMGs, these findings raise the possibility that for some women, breast cancer risk may initiate with subtle axial patterning defects that result in L-R asymmetric growth and pattern of the mammary ductal epithelium.This article is part of the themed issue 'Provocative questions in left-right asymmetry'.

Suppression of midkine gene promotes the antitumoral effect of cisplatin on human gastric cancer cell line AGS in vitro and in vivo via the modulation of Notch signaling pathway

Midkine (MK) is reported to be associated with the clinical stages and distant metastases in gastric cancer, and to positively regulate the proliferation of human gastric cancer cells. However, the possible mechanisms of MK in the development of gastric cancer are still not fully clarified. In this study, the therapeutic effect of MK inhibition in gastric cancer in vivo and in vitro was investigated, by knock-down of MK expression with a small interfering RNA (siRNA). MK was expressed in gastric carcinoma tissues and cancer cells. The cytotoxic effect of cisplatin on AGS cells in vitro was attenuated by recombinant human MK, but was promoted by suppressing MK expression via downregulating the Notch signaling pathway-related proteins (Notch 1, Notch 2, Delta-like 1 and Jagged 1). Suppression of MK expression also promoted the inhibitory effect of cisplatin on AGS cells in vivo. In concusion, suppression of midkine gene promoted the antitumoral effect of cisplatin on human gastric cell line AGS in vitro and in vivo via Notch signaling pathway.

Sensitivity of non-small cell lung cancer to erlotinib is regulated by the Notch/miR-223/FBXW7 pathway

Recent evidence supports a role for microRNA-223 (miR-223) in modulating tumor cell sensitivity to chemotherapeutic drugs; however, its role in cellular resistance to the effects of epidermal growth factor receptor tyrosine kinase inhibitors (EGFR-TKIs) used in treatment of non-small cell lung cancer (NSCLC) remains to be elucidated. The levels of miR-223 in parental cell line (HCC827) and erlotinib resistant HCC827 cell line (HCC827/ER) were detected by qRT-PCR. HCC827/ER cells were treated with MK-2206 to block the Akt signaling pathway or RO4929097 to block the Notch signaling pathway, and then transfected with an miR-223 inhibitor or interference expression plasmid of F-Box/WD repeat-containing protein 7 (FBXW7) or insulin-like growth factor 1 receptor (IGF1R). HCC827 cells were transfected with miR-223 mimics. Next, CCK-8, colony formation, and flow cytometric apoptosis assays were used to assess cell resistance to erlotinib. When compared with its expression in HCC827 cells, miR-223 expression was significantly up-regulated in HCC827/ER cells. Blocking either the Akt or Notch signaling pathway and reducing miR-223 expression resulted in decreased resistance in HCC827/ER cells. Conversely, increasing miR-223 expression induced cell resistance to erlotinib in HCC827 cells. miR-223 enhanced resistance to erlotinib by down-regulating FBXW7 expression. Reducing FBXW7 expression lowered resistance to erlotinib in HCC827/ER cells, while interference with expression of IGF1R produced no significant effect. This study demonstrated that NSCLC cells can up-regulate their levels of miR-223 expression via the Akt and Notch signaling pathways. miR-223 may serve as an important regulator of erlotinib sensitivity in NSCLC cells by targeting FBXW7.

NOTCH signalinio kelio ir ginekologinių piktybinių navikų sąsaja

Įvadas. Organizmo ląstelėse vykstančius procesus kontroliuoja įvairūs signaliniai keliai. Vienas iš jų yra NOTCH signalinis kelias. Nustatyta, kad dalinis NOTCH funkcijos praradimas arba nenormalus NOTCH signalo aktyvinimas susijęs su įvairiais žmogaus vystymosi sutrikimais ir ligomis.

Medžiaga ir metodika. Pagrindinis informacijos šaltinis ieškant duomenų – PubMed duomenų bazė.

Rezultatai. Straipsnyje nagrinėjama onkologinių ligų bei NOTCH signalinio kelio dalyvių sąsaja. NOTCH signalas, vystantis vėžiui, gali veikti dvejopai: kaip onkogenas ir kaip naviko augimo slopiklis. Tikslus tokio poveikio mechanizmas dar nėra žinomas. NOTCH signalinio kelio tyrimai svarbūs siekiant atrasti naujus vėžio gydymo būdus, farmakologiniais ir genetiniais metodais valdant NOTCH signalinį kelią. Šioje apžvalgoje daugiausia dėmesio skiriama ginekologiniams piktybiniams navikams, ypač gimdos kūno vėžiui.

Išvados. Pastarųjų metų mokslinių tyrimų duomenys rodo, kad NOTCH signalinis kelias yra neabejotinai svarbus formuojantis gimdos kūno vėžiui, todėl jo komponentai gali būti potencialūs prognoziniai biožymenys ir molekuliniai terapiniai taikiniai. Siekiant patikslinti NOTCH signalinio kelio dalyvių reikšmę bei jų sąveiką su kitų signalinių kelių dalyviais, kurie taip pat gali būti svarbūs formuojantis ir progresuojant gimdos kūno vėžiui, reikalingi tolesni šios srities moksliniai tyrimai.

Expression of Notch Gene and Its Impact on Survival of Patients with Resectable Non-small Cell Lung Cancer

BACKGROUND: Notch signaling has been demonstrated to frequently participate in the process of lung carcinogenesis. This study aimed to search Notch expression in non-small cell lung cancer (NSCLC) and its impact on survival.

METHODS: From 2001 to 2011, patients with diagnosis of NSCLC who received surgical resection were included. The expression of Notch gene was assessed by real-time polymerase chain reaction (RT-PCR). Clinical characteristics, histological types, disease stages, and outcomes were analyzed.

RESULTS: Ninety-seven patients with NSCLC being explored the expression of Notch gene (Notch1 - 4). Seventy-five patients (77.3%) were adenocarcinoma. Patients with adenocarcinoma had higher expression of Notch2 than other histology types (p < 0.001). Otherwise, patients with squamous cell carcinoma had relative higher expression of Notch1 and Notch3 expression (p = 0.014 and p = 0.032, respectively). Notch2 expression increased associated with patients with more advanced lung cancer stage. Patients who had cancer recurrence also had higher Notch2 expression (p = 0.008). The patient group with lung adenocarcinoma of both high Notch1 and Notch3 expression had a shorter median disease-free survival (DFS) (both high v.s both low: DFS, median, 7.2 v.s 25.3 months, p = 0.03). However, the expression of Notch gene had no impact on overall survival.

CONCLUSIONS: Patients with lung adenocarcinoma had higher Notch2 expression. Patients with higher Notch2 expression also had higher rate of cancer recurrence. Both higher Notch1 and Notch3 expression was associated with poor prognosis in lung adenocarcinoma.

Identification of 4-arylidene curcumin analogues as novel proteasome inhibitors for potential anticancer agents targeting 19S regulatory particle associated deubiquitinase

The proteasomal 19S regulatory particle (RP) associated deubiquitinases (DUBs) have attracted much attention owing to their potential as a therapeutic target for cancer therapy. Identification of new entities against 19S RP associated DUBs and illustration of the underlying mechanisms is crucial for discovery of novel proteasome blockers. In this study, a series of 4-arylidene curcumin analogues were identified as potent proteasome inhibitor by preferentially blocking deubiquitinase function of proteasomal 19S RP with moderate 20S CP inhibition. The most active compound 33 exhibited a major inhibitory effect on 19S RP-associated ubiquitin-specific proteases 14, along with a minor effect on ubiquitin C-terminal hydrolase 5, which resulted in dysfunction of proteasome, and subsequently accumulated ubiquitinated proteins (such as IκB) in several cancer cells. Remarkably, though both 19S RP and 20S CP inhibition induced significantly endoplasmic reticulum stress and triggered caspase-12/9 pathway activation to promote cancer cell apoptosis, the 19S RP inhibition by 33 avoided slow onset time, Bcl-2 overexpression, and PERK-phosphorylation, which contribute to the deficiencies of clinical drug Bortezomib. These systematic studies provided insights in the development of novel proteasome inhibitors for cancer treatment.

Bayesian model of signal rewiring reveals mechanisms of gene dysregulation in acquired drug resistance in breast cancer

Small molecule inhibitors, such as lapatinib, are effective against breast cancer in clinical trials, but tumor cells ultimately acquire resistance to the drug. Maintaining sensitization to drug action is essential for durable growth inhibition. Recently, adaptive reprogramming of signaling circuitry has been identified as a major cause of acquired resistance. We developed a computational framework using a Bayesian statistical approach to model signal rewiring in acquired resistance. We used the p₁-model to infer potential aberrant gene-pairs with differential posterior probabilities of appearing in resistant-vs-parental networks. Results were obtained using matched gene expression profiles under resistant and parental conditions. Using two lapatinib-treated ErbB2-positive breast cancer cell-lines: SKBR3 and BT474, our method identified similar dysregulated signaling pathways including EGFR-related pathways as well as other receptor-related pathways, many of which were reported previously as compensatory pathways of EGFR-inhibition via signaling cross-talk. A manual literature survey provided strong evidence that aberrant signaling activities in dysregulated pathways are closely related to acquired resistance in EGFR tyrosine kinase inhibitors. Our approach predicted literature-supported dysregulated pathways complementary to both node-centric (SPIA, DAVID, and GATHER) and edge-centric (ESEA and PAGI) methods. Moreover, by proposing a novel pattern of aberrant signaling called V-structures, we observed that genes were dysregulated in resistant-vs-sensitive conditions when they were involved in the switch of dependencies from targeted to bypass signaling events. A literature survey of some important V-structures suggested they play a role in breast cancer metastasis and/or acquired resistance to EGFR-TKIs, where the mRNA changes of TGFBR2, LEF1 and TP53 in resistant-vs-sensitive conditions were related to the dependency switch from targeted to bypass signaling links. Our results suggest many signaling pathway structures are compromised in acquired resistance, and V-structures of aberrant signaling within/among those pathways may provide further insights into the bypass mechanism of targeted inhibition.

Clinical implications of APEX1 and Jagged1 as chemoresistance factors in biliary tract cancer

Purpose

Biliary cancer is a highly malignant neoplasm with poor prognosis and most patients need to undergo palliative chemotherapy, however major clinical problem associated with the use of chemotherapy is chemoresistance. So far, we aimed at investigating clinical implications of apurinic/apyrimidinic endodeoxyribonuclease 1 (APEX1) and Jagged1 as chemoresistance factors in biliary tract cancer.

Methods

We used 5 human biliary tract cancer cell lines (SNU-245, SNU-308, SNU-478, SNU-1079, and SNU-1196), and investigated the chemosensitivity of APEX1 and Jagged1 through 3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide (MTT) assay and Western blot. Alternately, the 10 patients of advanced biliary cancer consist of 2 group according to the chemotherapy response examined by immunohistochemistry using APEX1 and Jagged1 antibody, and protein expression level was scored for staining intensity and percent positive cell.

Results

The result of MTT assay after APEX1 knockdown showed that strong coexpression of APEX1 and Jagged1 cell line (SNU-245, SNU-1079, and SNU-1196) showed a greater decrease in IC₅₀ of chemotherapeutic agent (5-fluorouracil, gemcitabine and cisplatin). The Western blot analysis of APEX1 and Jagged1 expression in biliary cancer cell lines after APEX1 knockdown definitively demonstrated decreased Jagged1 expression. The APEX1 and Jagged1expression level of immunohistochemistry represented that chemorefractory patients had higher than chemoresponsive patients.

Conclusion

These results demonstrate that simultaneous high expression of APEX1 and Jagged1 is associated with chemoresistance in biliary cancer and suggest that is a potential therapeutic target for chemoresistance in advanced biliary cancer.

The Varied Roles of Notch in Cancer

Notch receptors influence cellular behavior by participating in a seemingly simple signaling pathway, but outcomes produced by Notch signaling are remarkably varied depending on signal dose and cell context. Here, after briefly reviewing new insights into physiologic mechanisms of Notch signaling in healthy tissues and defects in Notch signaling that contribute to congenital disorders and viral infection, we discuss the varied roles of Notch in cancer, focusing on cell autonomous activities that may be either oncogenic or tumor suppressive.

Down-regulation of miR-26b induces cisplatin resistance in nasopharyngeal carcinoma by repressing JAG1

Therapy against nasopharyngeal carcinoma (NPC) is hurdled by chemoresistance. Recent studies found that microRNA (miRNA) are important regulators of cancer resistance. In this study, we aimed to explore the role and mechanism of miR‐26b in regulating NPC cisplatin (CDDP) resistance. Real‐time PCR was used to evaluate miR‐26b levels in CDDP‐resistant and CDDP‐sensitive NPC cells, as well as human NPC tissues. MiR‐26b was ectopically overexpressed in CDDP‐resistant cells, followed by monitoring changes in cell viability and apoptosis. Interaction between JAG1 and miR‐26b was characterized by dual‐luciferase reporter assay. Furthermore, we investigated whether ectopic JAG1 expression reversed CDDP sensitivity induced by miR‐26b overexpression. The effect of FOXD3 down‐regulation on miR‐26b was also evaluated. Our results indicate that miR‐26b was lower in the CDDP‐resistant NPC cells, human NPC tissue, particularly in secondary metastases. Ectopic expression of miR‐26b sensitized NPC cells to CDDP. JAG1 is a target of miR‐26b, and its expression is inversely correlated with miR‐26b. Overexpression of JAG1 reversed the CDDP sensitivity induced by miR‐26b overexpression. FOXD3 expression was also down‐regulated in CDDP‐resistant NPC. FOXD3 promoted miR‐26b expression and down‐regulation of FOXD3 suppressed miR‐26b expression. Down‐regulation of miR‐26b is closely correlated with the CDDP resistance in NPC.

Notch-1 Confers Chemoresistance in Lung Adenocarcinoma to Taxanes through AP-1/microRNA-451 Mediated Regulation of MDR-1

We previously demonstrated that expression of Notch-1 is associated with poor prognosis in lung adenocarcinoma (LAD) patients. The aim of this study is to reveal whether Notch-1 was associated with Taxanes-resistant LAD and, the underlying mechanisms. We collected 39 patients of advanced LAD treated with Taxanes and found that positive Notch-1 expression is closely related to LAD lymph node metastasis, recurrence and poorer prognosis, and Notch-1 acts as an independent poor prognostic factor in LAD by multivariate analysis with Cox regression model. Then, by using the Docetaxel (DTX)-resistant LAD cell lines that we established previously, we found that Notch-1 contributes to resistance of LAD cells to DTX in vitro, and inhibition of Notch-1 sensitizes LAD to DTX in vivo. We further demonstrated that Notch-1 mediates chemoresistance response and strengthens proliferation capacity in LAD cells partially through negative regulation of miR-451 by transcription factor AP-1. Moreover, we found that MDR-1 is a direct target of miR-451 and influences chemoresistance of LAD cells. Taken together, our data revealed a novel Notch-1/AP-1/miR-451/MDR-1 signaling axis, and suggested a new therapeutic strategy of combining DTX with Notch inhibitors to treat DTX-resistant LAD.

Molecular classification of gastric cancer: Towards a pathway-driven targeted therapy

Gastric cancer (GC) is the third leading cause of cancer mortality worldwide. Although surgical resection is a potentially curative approach for localized cases of GC, most cases of GC are diagnosed in an advanced, non-curable stage and the response to traditional chemotherapy is limited. Fortunately, recent advances in our understanding of the molecular mechanisms that mediate GC hold great promise for the development of more effective treatment strategies. In this review, an overview of the morphological classification, current treatment approaches, and molecular alterations that have been characterized for GC are provided. In particular, the most recent molecular classification of GC and alterations identified in relevant signaling pathways, including ErbB, VEGF, PI3K/AKT/mTOR, and HGF/MET signaling pathways, are described, as well as inhibitors of these pathways. An overview of the completed and active clinical trials related to these signaling pathways are also summarized. Finally, insights regarding emerging stem cell pathways are described, and may provide additional novel markers for the development of therapeutic agents against GC. The development of more effective agents and the identification of biomarkers that can be used for the diagnosis, prognosis, and individualized therapy for GC patients, have the potential to improve the efficacy, safety, and cost-effectiveness for GC treatments.

Targeting leukemia stem cells: which pathways drive self-renewal activity in T-cell acute lymphoblastic leukemia?

T-Cell acute lymphoblastic leukemia (t-all) is a malignancy of white blood cells, characterized by an uncontrolled accumulation of T-cell progenitors. During leukemic progression, immature T cells grow abnormally and crowd into the bone marrow, preventing it from making normal blood cells and spilling out into the bloodstream. Recent studies suggest that only discrete cell populations that possess the ability to recreate the entire tumour might be responsible for the initiation and propagation of t-all. Those unique cells are commonly called "cancer stem cells" or, in the case of hematopoietic malignancies, "leukemia stem cells" (lscs). Like normal hematopoietic stem cells, lscs are thought to be capable of self-renewal, during which, by asymmetrical division, they give rise to an identical copy of themselves as well as to a daughter cell that is no longer capable of self-renewal activity and represents a more "differentiated" progeny. Here, we review the main pathways of self-renewal activity in lscs, focusing on their involvement in the maintenance and development of t-all. New stem cell-directed therapies and lsc-targeted agents are also discussed.

γ Secretase inhibitor BMS-708163 reverses resistance to EGFR inhibitor via the PI3K/Akt pathway in lung cancer

Lung adenocarcinoma cells harboring epidermal growth factor receptor (EGFR) mutations are sensitive to EGFR tyrosine kinase inhibitor (TKI). Acquired resistance to EGFR TKI develops after prolonged treatment. The aim of this study was to investigate the effect of the novel γ secretase inhibitor BMS-708163 on acquired resistance to the EGFR TKI gefitinib. We did not observe known mechanisms of acquired resistance to EGFR TKI, including the EGFR T790M mutation and MET gene amplification in the gefitinib-resistant PC9/AB2 cells. BMS-708163 inhibited PI3K/Akt expression and sensitized PC9/AB2 cells to gefitinib-induced cytotoxicity. In contrast, BMS-708163 had no significant effect on gefitinib sensitivity in PC9 parental cells. Combined treatment with BMS-708163 and gefitinib induced high levels of apoptosis. Our in vivo studies showed that combined treatment of gefitinib and BMS-708163 inhibited the growth of PC9/AB2 xenografts. In conclusion, our data show that combined treatment of gefitinib and γ secretase inhibitors may be useful for treating lung adenocarcinomas harboring EGFR mutations with acquired gefitinib resistance.

Promising molecular mechanisms responsible for gemcitabine resistance in cancer

Gemcitabine is the first-line treatment for pancreatic ductual adenocarcinoma (PDAC) as well as acts against a wide range of other solid tumors. Patients usually have a good initial response to gemcitabine-based chemotherapy but would eventually develop resistance. To improve survival and prognosis of cancer patients, better understanding of the mechanisms responsible for gemcitabine resistance and discovery of new therapeutic strategies are in great need. Amounting evidence indicate that the developmental pathways, such as Hedgehog (Hh), Wnt and Notch, become reactivated in gemcitabine-resistant cancer cells. Thus, the strategies for targeting these pathways may sensitize cancer cells to gemcitabine treatment. In this review, we will summarize recent development in this area of research and discuss strategies to overcome gemcitabine resistance. Given the cross-talk between these three developmental signaling pathways, designing clinical trials using a cocktail of inhibitory agents targeting all these pathways may be more effective. Ultimately, our hope is that targeting these developmental pathways may be an effective way to improve the gemcitabine treatment outcome in cancer patients.

Lateral inhibition of Notch signaling in neoplastic cells

During normal development, heterogeneous expression of Notch ligands can result in pathway suppression in the signal-sending cell, a process known as lateral inhibition. It is unclear if an analogous phenomenon occurs in malignant cells. We observed significant induction of Notch ligands in glioblastoma neurospheres and pancreatic carcinoma cells cultured in low oxygen, suggesting that this phenomenon could occur around hypoxic regions. To model lateral inhibition in these tumors, the ligand Jagged1 was overexpressed in glioblastoma and pancreatic carcinoma cells, resulting in overall induction of pathway targets. However, when ligand high and ligand low cells from a single line were co-cultured and then separated, we noted suppression of Notch pathway targets in the former and induction in the latter, suggesting that neoplastic lateral inhibition can occur. We also found that repression of Notch pathway targets in signal-sending cells may occur through the activity of a Notch ligand intracellular domain, which translocates into the nucleus. Understanding how this neoplastic lateral inhibition process functions in cancer cells may be important in targeting ligand driven Notch signaling in solid tumors.

Epidermal growth factor receptor status and Notch inhibition in non-small cell lung cancer cells

BACKGROUND

Notch may behave as an oncogene or a tumor suppressor gene in lung cancer cells. Notch receptor undergoes cleavage by enzymes, including γ-secretase, generating the active Notch intracellular domain (NICD). The aim of the present study was to investigate the effect of DAPT, a γ-secretase inhibitor, in non-small cell lung cancer (NSCLC) cells, as well as the impact of epidermal growth factor (EGF) that is over-expressed by NSCLC cells, on Notch signaling. H23, A549, H661 and HCC827 human NSCLC cell lines were used, expressing various NICD and EGF receptor (EGFR) protein levels.

RESULTS

DAPT decreased the number of H661 cells in a concentration-dependent manner, while it had a small effect on H23 and A549 cells and no effect on HCC827 cells that carry mutated EGFR. Notch inhibition did not affect the stimulatory effect of EGF on cell proliferation, while EGF prevented DAPT-induced NICD decrease in H23 and H661 cells. The type of cell death induced by DAPT seems to depend on the cell type.

CONCLUSIONS

Our data indicate that inhibition of Notch cleavage may not affect cell number in the presence of EGFR mutations and that EGFR may affect Notch signalling suggesting that a dual inhibition of these pathways might be promising in NSCLC.

Prognostic values of Notch receptors in breast cancer

Notch receptors are frequently deregulated in several human malignancies including human breast cancer. Activation of Notch has been reported to cause mammary carcinomas in mice. However, the prognostic value of individual Notch receptors in breast cancer (BC) patients remains elusive. In the current study, we investigated the prognostic value of Notch receptors in human BC patients. More specifically, we investigated the prognostic value of four Notch receptors in breast cancer patients through "the Kaplan-Meier plotter" (KM plotter) database, in which updated gene expression data and survival information are from a total of 3554 breast cancer patients. Our results showed that Notch1 messenger RNA (mRNA) high expression was correlated to worsen overall survival (OS) in PgR-negative BC patients. Notch2, Notch3, and Notch4 mRNA high expressions were found to be correlated to better OS for all breast cancer patients. Notch2 was also found to be correlated to better OS in lymph node-negative breast cancer patients and HER2-positive breast cancer patients. These results will be useful for better understanding of the heterogeneity and complexity in the molecular biology of breast cancer and for developing tools to more accurately predict their prognosis and design their customized treatment strategies.

Notch1 pathway in adrenocortical carcinomas: correlations with clinical outcome

Previous SNP array analyses have revealed genomic alterations of the Notch pathway as being the most frequent abnormality in adrenocortical tumors (ACTs). The aim of the present study was to evaluate the expression of components of Notch signaling in ACTs and to correlate them with clinical outcome. The mRNA expression of JAG1, NOTCH1, and selected target genes of NOTCH1 (HES1, HES5, and HEY2) was evaluated in 80 fresh frozen samples (28 normal adrenal glands (NAGs), 24 adenomas (ACAs), and 28 carcinomas (ACCs)) by quantitative RT-PCR. Immunohistochemistry was performed in 221 tissues on paraffin slides (16 NAGs, 27 ACAs, and 178 ACCs) for JAG1, activated NOTCH1 (aNOTCH1), and HEY2. An independent ACC validation cohort (n=77) was then also investigated. HEY2 mRNA expression was higher in ACCs than it was in ACAs (P<0.05). The protein expression of all of the factors was high (H-score 2-3) in a larger proportion of ACCs as compared to ACAs and NAGs (JAG1 in 27, 15, and 10%; aNOTCH1 in 13, 8, and 0%; HEY2 in 66, 61, and 33% respectively, all P<0.001). High JAG1 expression was associated with earlier tumor stages and lower numbers of metastases in ACCs (both P=0.08) and favorably impacted overall and progression-free survival (PFS) (131 vs 30 months, hazard ratio (HR) 0.45, and 37 vs 9 months, HR 0.51, both P<0.005). This impact on overall survival (OS) was confirmed in the validation cohort. No such association was observed for aNOTCH1 or HEY2. In conclusion, different components of the Notch1 signaling pathway are overexpressed in ACCs, which suggests a role for the pathway in malignant transformation. However, JAG1 is overexpressed in a subgroup of ACCs with a better clinical outcome.

A novel Monoclonal Antibody against Notch1 Targets Leukemia-associated Mutant Notch1 and Depletes Therapy Resistant Cancer Stem Cells in Solid Tumors

Higher Notch signaling is known to be associated with hematological and solid cancers. We developed a potential immunotherapeutic monoclonal antibody (MAb) specific for the Negative Regulatory Region of Notch1 (NRR). The MAb604.107 exhibited higher affinity for the "Gain-of-function" mutants of Notch1 NRR associated with T Acute lymphoblastic Leukemia (T-ALL). Modeling of the mutant NRR with 12 amino-acid insertion demonstrated "opening" resulting in exposure of the S2-cleavage site leading to activated Notch1 signaling. The MAb, at low concentrations (1-2 μg/ml), inhibited elevated ligand-independent Notch1 signaling of NRR mutants, augmented effect of Thapsigargin, an inhibitor of mutant Notch1, but had no effect on the wild-type Notch1. The antibody decreased proliferation of the primary T-ALL cells and depleted leukemia initiating CD34/CD44 high population. At relatively high concentrations, (10-20 μg/ml), the MAb affected Notch1 signaling in the breast and colon cancer cell lines. The Notch-high cells sorted from solid-tumor cell lines exhibited characteristics of cancer stem cells, which were inhibited by the MAb. The antibody also increased the sensitivity to Doxorubucinirubicin. Further, the MAb impeded the growth of xenografts from breast and colon cancer cells potentiated regression of the tumors along with Doxorubucin. Thus, this antibody is potential immunotherapeutic tool for different cancers.