Autocrine Sonic hedgehog signaling promotes gastric cancer proliferation through induction of phospholipase Cγ1 and the ERK1/2 pathway

Therapeutic potential of hedgehog signaling in advanced cancer types

In this chapter, we have made an attempt to elucidate the relevance of hedgehog signaling pathway in tumorigenesis. Here, we have described different types of hedgehog signaling (canonical and non-canonical) with emphasis on the different mechanisms (mutation-driven, autocrine, paracrine and reverse paracrine) it adopts during tumorigenesis. We have discussed the role of hedgehog signaling in regulating cell proliferation, invasion and epithelial-to-mesenchymal transition in both local and advanced cancer types, as reported in different studies based on preclinical and clinical models. We have specifically addressed the role of hedgehog signaling in aggressive neuroendocrine tumors as well. We have also elaborated on the studies showing therapeutic relevance of the inhibitors of hedgehog signaling in cancer. Evidence of the crosstalk of hedgehog signaling components with other signaling pathways and treatment resistance due to tumor heterogeneity have also been briefly discussed. Together, we have tried to put forward a compilation of the studies on therapeutic potential of hedgehog signaling in various cancers, specifically aggressive tumor types with a perspective into what is lacking and demands further investigation.

Gastric cancer and mesenchymal stem cell-derived exosomes: from pro-tumorigenic effects to anti-cancer vehicles

Gastric cancer (GC) is one of the most prevalent malignancies in the world, with a high mortality rate in both women and men. Conventional treatments, like chemotherapy, radiotherapy and surgery, are facing some drawbacks like acquired drug resistance and various side effects, leading to cancer recurrence and increased morbidity; thus, development of novel approaches in targeted therapy would be very beneficial. Exosomes, extracellular vesicles with a size distribution of sub-150 nm, interplay in physiological and pathophysiological cell-cell communications and can pave the way for targeted cancer therapy. Accumulating pieces of evidence have indicated that exosomes derived from mesenchymal stem cells (MSC-EXs) can act as a double-edged sword in some cancers. The purpose of this review is to assess the differences between stem cell therapy and exosome therapy. Moreover, our aim is to demonstrate how naïve MSCs transform into GC-MSCs in the tumor microenvironment. Additionally, the tumorigenic and anti-proliferation effects of MSC-EXs derived from different origins were investigated. Finally, we suggest potential modifications and combination options that involve utilizing MSC-EXs from the foreskin and umbilical cord as promising sources to enhance the efficacy of gastric cancer treatment. This approach is presented in contrast to bone marrow cells, which are more heterogeneous, age-related, and are also easily affected by the patient's circulation system.

Hedgehog signaling in tissue homeostasis, cancers, and targeted therapies

The past decade has seen significant advances in our understanding of Hedgehog (HH) signaling pathway in various biological events. HH signaling pathway exerts its biological effects through a complex signaling cascade involved with primary cilium. HH signaling pathway has important functions in embryonic development and tissue homeostasis. It plays a central role in the regulation of the proliferation and differentiation of adult stem cells. Importantly, it has become increasingly clear that HH signaling pathway is associated with increased cancer prevalence, malignant progression, poor prognosis and even increased mortality. Understanding the integrative nature of HH signaling pathway has opened up the potential for new therapeutic targets for cancer. A variety of drugs have been developed, including small molecule inhibitors, natural compounds, and long non-coding RNA (LncRNA), some of which are approved for clinical use. This review outlines recent discoveries of HH signaling in tissue homeostasis and cancer and discusses how these advances are paving the way for the development of new biologically based therapies for cancer. Furthermore, we address status quo and limitations of targeted therapies of HH signaling pathway. Insights from this review will help readers understand the function of HH signaling in homeostasis and cancer, as well as opportunities and challenges of therapeutic targets for cancer.

Weierning, a Chinese patent medicine, improves chronic atrophic gastritis with intestinal metaplasia

ETHNOPHARMACOLOGICAL RELEVANCE

Weierning tablet (WEN) is a traditional Chinese patent medicine widely used in clinical for chronic atrophic gastritis (CAG) therapy for years. However, the underlying mechanisms of WEN on anti-CAG are still unveiled.

AIM OF THE STUDY

The present study aimed to elucidate the characteristic function of WEN on anti-CAG and to illuminate its potential mechanism.

METHODS

The CAG model was established by gavage rats with a modeling solution (consisting of 2% sodium salicylate and 30% alcohol) with irregular diets and free access to 0.1% ammonia solution for two months on end. An enzyme-linked immunosorbent assay was used to measure the serum levels of gastrin, pepsinogen, and inflammatory cytokines. qRT-PCR was applied to measure mRNA expressions of IL-6, IL-18, IL-10, TNF-α, and γ-IFN in gastric tissue. Pathological changes and the ultrastructure of gastric mucosa were examined by hematoxylin and eosin staining and transmission electron microscopy, respectively. AB-PAS staining was applied to observe the intestinal metaplasia of gastric mucosa. Immunohistochemistry and Western blot were used to measure the expression levels of mitochondria apoptosis-related proteins and Hedgehog pathway-related proteins in gastric tissues. Expressions of Cdx2 and Muc2 protein were determined by immunofluorescent staining.

RESULTS

WEN could dose-dependently lower the serum level of IL-1β and the mRNA expressions of IL-6, IL-8, IL-10, TNF-α, and γ-IFN in gastric tissue. Also, WEN significantly alleviated the collagen deposition in gastric submucosa, regulated the expressions of Bax, Cleaved-caspase9, Bcl2, and Cytochrome c to reduce the apoptosis of gastric mucosa epithelial cells, and maintained the integrity of the gastric mucosal barrier. Moreover, WEN could reduce protein expressions of Cdx2, Muc2, Shh, Gli1, and Smo, and reverse intestinal metaplasia of gastric mucosa to block the progress of CAG.

CONCLUSION

This study demonstrated a positive effect of WEN on improving CAG and reverse intestinal metaplasia. These functions were related to the suppression of gastric mucosal cells' apoptosis and the inhibition of Hedgehog pathways' activation.

Hedgehog/GLI and gastric cancer: Research progress and current status

Hedgehog/GLI (Hh/GLI) is an important signaling pathway. It has been confirmed in various cancer studies that mutated or dysregulated Hh signals may be the behavioral phenotype of tumors, leading to the occurrence of various cancers. The abnormally activated Hh pathway endows tumor cells with a tendency to occur, proliferate, and migrate. In recent years, studies have found that the Hh signaling pathway induces gastric cancer (GC) invasion and epithelial mesenchymal transition. This article reviews the research progress and current status of Hh/GLI related to GC. Unveiling the new veil of GC occurrence will open a new approach for targeted therapy of this malignancy.

The emerging roles of Hedgehog signaling in tumor immune microenvironment

The Hedgehog (Hh) signaling pathway is pervasively involved in human malignancies, making it an effective target for cancer treatment for decades. In addition to its direct role in regulating cancer cell attributes, recent work indicates that it has an immunoregulatory effect on tumor microenvironments. An integrated understanding of these actions of Hh signaling pathway in tumor cells and tumor microenvironments will pave the way for novel tumor treatments and further advances in anti-tumor immunotherapy. In this review, we discuss the most recent research about Hh signaling pathway transduction, with a particular emphasis on its role in modulating tumor immune/stroma cell phenotype and function, such as macrophage polarity, T cell response, and fibroblast activation, as well as their mutual interactions between tumor cells and nonneoplastic cells. We also summarize the recent advances in the development of Hh pathway inhibitors and nanoparticle formulation for Hh pathway modulation. We suggest that targeting Hh signaling effects on both tumor cells and tumor immune microenvironments could be more synergistic for cancer treatment.

Landscape of Druggable Molecular Pathways Downstream of Genomic CDH1/Cadherin-1 Alterations in Gastric Cancer

Loss of CDH1/Cadherin-1 is a common step towards the acquisition of an abnormal epithelial phenotype. In gastric cancer (GC), mutation and/or downregulation of CDH1/Cadherin-1 is recurrent in sporadic and hereditary diffuse GC type. To approach the molecular events downstream of CDH1/Cadherin-1 alterations and their relevance in gastric carcinogenesis, we queried public databases for genetic and DNA methylation data in search of molecular signatures with a still-uncertain role in the pathological mechanism of GC. In all GC subtypes, modulated genes correlating with CDH1/Cadherin-1 aberrations are associated with stem cell and epithelial-to-mesenchymal transition pathways. A higher level of genes upregulated in CDH1-mutated GC cases is associated with reduced overall survival. In the diffuse GC (DGC) subtype, genes downregulated in CDH1-mutated compared to cases with wild type CDH1/Cadherin-1 resulted in being strongly intertwined with the DREAM complex. The inverse correlation between hypermethylated CpGs and CDH1/Cadherin-1 transcription in diverse subtypes implies a common epigenetic program. We identified nonredundant protein-encoding isoforms of 22 genes among those differentially expressed in GC compared to normal stomach. These unique proteins represent potential agents involved in cell transformation and candidate therapeutic targets. Meanwhile, drug-induced and CDH1/Cadherin-1 mutation-related gene expression comparison predicts FIT, GR-127935 hydrochloride, amiodarone hydrochloride in GC and BRD-K55722623, BRD-K13169950, and AY 9944 in DGC as the most effective treatments, providing cues for the design of combined pharmacological treatments. By integrating genetic and epigenetic aspects with their expected functional outcome, we unveiled promising targets for combinatorial pharmacological treatments of GC.

Role of sonic hedgehog ligand in gastric cancer therapeutics

Purpose

The abnormal activation of the sonic hedgehog (SHH) signaling pathway is responsible for the progression of several types of cancers including Gastric Cancer (GC). SHH has been associated with the activation of different signaling pathways. Therefore, in this study, we investigated messenger RNA (mRNA) and protein expression of SHH in gastric malignancies and possible correlation with various clinicopathological parameters.

Materials and Methods

A total of 53 surgically resected tumors and adjacent histologically normal tissues from GC patients were investigated in study subjects. A quantitative real-time polymerase chain reaction and immunohistochemistry methods were used for expression analysis of SHH.

Results

At mRNA level, SHH was overexpressed in 60% (27/45) of GC cases as compared to their adjacent normal tissues. SHH immunohistochemical analysis revealed abundant cytoplasmic localization and overexpression in 43.39% (23/53) of GC tissues. SHH overexpression was not associated with any of the clinicopathological parameters.

Conclusion

Our results showed that SHH is dysregulated in GC and might be considered as a biomarker for GC progression and can be used as a target in cancer therapeutics.

Effect of the elastin-derived peptides (VGVAPG and VVGPGA) on breast (MCF-7) and lung (A549) cancer cell lines in vitro

Tissues are subjected to dynamic communication between cells and the extracellular matrix (ECM), resulting in ECM remodeling. One of the ECM components is elastin, which releases elastin-derived peptides (EDPs) during the aging process. Therefore, the aim of the present study was to evaluate the impact of the VGVAPG hexapeptide and elastin-like peptide VVGPGA (control) on certain metabolism parameters in human breast adenocarcinoma (MCF-7) and human lung carcinoma (A549) cell lines. The results did not show a significant effect of the peptides on metabolic activity and caspase-3 activity. However, more specific analysis revealed that VGVAPG and VVGPGA were able to increase KI67 protein expression in both tested cell lines after 24-h treatment. Moreover, the same correlation was observed at the KI67 gene level. VGVAPG also increased the P53, ATM and SHH gene expression in the A549 cells up to 19.08%, 20.74%, and 28.77%, respectively. Interestingly, the VGVAPG peptide exerted an effect on the expression of antioxidant enzymes SOD2 and CAT in the A549 and MCF-7 cells, especially after the 24-h treatment. Lastly, both peptides influenced the CAV1 and CLTC1 expression. Our results show that the tested EDPs have an effect on both A549 and MCF-7 cells at the cellular level. This may be correlated with the multidrug-resistance (MDR) phenotype in these cancer cells, which is an emerging problem in the current anticancer treatment. However, more research is needed in this field.

Noncoding RNAs related to the hedgehog pathway in cancer: clinical implications and future perspectives

Cancer is a type of malignant affliction threatening human health worldwide; however, the molecular mechanism of cancer pathogenesis remains to be elusive. The oncogenic hedgehog (Hh) pathway is a highly evolutionarily conserved signaling pathway in which the hedgehog-Patched complex is internalized to cellular lysosomes for degradation, resulting in the release of Smoothened inhibition and producing downstream intracellular signals. Noncoding RNAs (ncRNAs) with diversified regulatory functions have the potency of controlling cellular processes. Compelling evidence reveals that Hh pathway, ncRNAs, or their crosstalk play complicated roles in the initiation, metastasis, apoptosis and drug resistance of cancer, allowing ncRNAs related to the Hh pathway to serve as clinical biomarkers for targeted cancer therapy. In this review, we attempt to depict the multiple patterns of ncRNAs in the progression of malignant tumors via interactions with the Hh crucial elements in order to better understand the complex regulatory mechanism, and focus on Hh associated ncRNA therapeutics aimed at boosting their application in the clinical setting.

Hedgehog Signaling Pathway Proteins in Prognosis of Pancreatic Ductal Adenocarcinoma and Its Differentiation From Chronic Pancreatitis

OBJECTIVES

The Hedgehog signaling pathway (Hh) probably plays a role in development and progression of pancreatic ductal adenocarcinoma (PDAC).

METHODS

In our study, 114 patients (83 with PDAC and 31 with chronic pancreatitis [CP]) after pancreatic surgery were enrolled. The immunoexpression of Sonic hedgehog (Shh), Smoothened (Smo), and Glioblastoma transcription factor 1 (Gli1) and Ki-67 were detected in tissue specimens.

RESULTS

Mean (standard deviation) immunoexpression of all Hh pathway molecules was significantly higher in PDAC than in CP patients: Shh, 2.24 (0.57) versus 1.17 (0.25) (P < 0.01); Smo, 2.62 (0.34) versus 1.21 (0.23) (P < 0.01); and Gli1, 1.74 (0.74) versus 1.15 (0.72) (P < 0.01). Patients with a lower expression level (z score <0) of Shh and Ki-67 have longer overall survival when compared with z score >0 (15.97 vs 8.53 months [P = 0.0087] and 15.20 vs 5.53 months [P = 0.0004], respectively). In addition, Shh sensitivity in PDAC detection was 84.3%; specificity, 93.5%; positive predictive value, 97.2%; and negative predictive value, 69%.

CONCLUSIONS

Our results suggest the prognostic role of the Hh pathway in PDAC and a role in the differential diagnosis with CP.

Ferroptosis Mediation Patterns Reveal Novel Tool to Implicate Immunotherapy and Multi-Omics Characteristics in Bladder Cancer

Background: The regulatory role of ferroptosis in malignant tumours has been recently demonstrated. However, the potential roles of ferroptosis mediation patterns in bladder cancer remain elusive. Materials and Methods: The ferroptosis mediation patterns of 889 bladder cancer samples were comprehensively evaluated based on ferroptosis-related genes. The underlying correlations between these mediation patterns and multi-omic characteristics of bladder cancer were systematically analysed. The ferroptosis mediation patterns of individual samples were quantified by ferropscore using the principal component analysis algorithm. The typical ferroptosis-related genes with prognostic roles were further randomly validated using immunohistochemical staining, real-time polymerase chain reaction and western blotting. Results: Three different ferroptosis mediation patterns were identified. The abundance of infiltration of 23 immune cells was different among the three mediation patterns. The quantification of ferroptosis mediation patterns in individual samples served as a promising tool for predicting patient survival outcomes; immune cell infiltration abundance; tumour mutation burden; oncogenic mutation status and tumour grade, stage and molecular subtypes. Low ferropscore combined with high tumour mutation burden was associated with the best survival prognosis. Expressions of PD-L1 (p < 0.001), PD-1 (p = 0.002) and CTLA-4 (p = 0.003) were all significantly upregulated in the high ferropscore group. Low ferropscores also predicted good immunotherapy response for anti-CTLA4 strategy. The mRNA and protein levels of FADS2, a typical ferroptosis-related gene used in the study, were higher in bladder cancer cell lines than in controlled SV-HUC-1 cells. In addition, immunohistochemical staining revealed significantly higher expression levels of FADS2 in human bladder cancer tumour tissues than in normal tissues. Conclusion: This study identified three distinct ferroptosis mediation patterns in bladder cancer. Quantification of ferroptosis mediation patterns in individual samples may help to improve the understanding of multiomic characteristics and guide future immunotherapy responses to bladder cancer.

Recent advances in understanding the molecular role of phosphoinositide-specific phospholipase C gamma 1 as an emerging onco-driver and novel therapeutic target in human carcinogenesis

Phosphoinositide metabolism is crucial intracellular signaling system that regulates a plethora of biological functions including mitogenesis, cell proliferation and division. Phospholipase C gamma 1 (PLCγ1) which belongs to phosphoinositide-specific phospholipase C (PLC) family, is activated by many extracellular stimuli including hormones, neurotransmitters, growth factors and modulates several cellular and physiological functions necessary for tumorigenesis such as cell survival, migration, invasion and angiogenesis by generating inositol 1,4,5-triphosphate (IP3) and diacylglycerol (DAG) via hydrolysis of phosphatidylinositol 4,5-biphosphate (PIP2). Cancer remains as a leading cause of global mortality and aberrant expression and regulation of PLCγ1 is linked to a plethora of deadly human cancers including carcinomas of the breast, lung, pancreas, stomach, prostate and ovary. Although PLCγ1 cross-talks with many onco-drivers and signaling circuits including PI3K, AKT, HIF1-α and RAF/MEK/ERK cascade, its precise role in carcinogenesis is not completely understood. This review comprehensively discussed the status quo of this ubiquitously expressed phospholipase as a tumor driver and highlighted its significance as a novel therapeutic target in cancer. Furthermore, we have highlighted the significance of somatic driver mutations in PLCG1 gene and molecular roles of PLCγ1 in several major human cancers, a knowledgebase that can be utilized to develop novel, isoform-specific small molecule inhibitors of PLCγ1.

Hedgehog signaling in gastrointestinal carcinogenesis and the gastrointestinal tumor microenvironment

The Hedgehog (HH) signaling pathway plays important roles in gastrointestinal carcinogenesis and the gastrointestinal tumor microenvironment (TME). Aberrant HH signaling activation may accelerate the growth of gastrointestinal tumors and lead to tumor immune tolerance and drug resistance. The interaction between HH signaling and the TME is intimately involved in these processes, for example, tumor growth, tumor immune tolerance, inflammation, and drug resistance. Evidence indicates that inflammatory factors in the TME, such as interleukin 6 (IL-6) and interferon-γ (IFN-γ), macrophages, and T cell-dependent immune responses, play a vital role in tumor growth by affecting the HH signaling pathway. Moreover, inhibition of proliferating cancer-associated fibroblasts (CAFs) and inflammatory factors can normalize the TME by suppressing HH signaling. Furthermore, aberrant HH signaling activation is favorable to both the proliferation of cancer stem cells (CSCs) and the drug resistance of gastrointestinal tumors. This review discusses the current understanding of the role and mechanism of aberrant HH signaling activation in gastrointestinal carcinogenesis, the gastrointestinal TME, tumor immune tolerance and drug resistance and highlights the underlying therapeutic opportunities.

Clinical and prognostic significances of cancer stem cell markers in gastric cancer patients: a systematic review and meta-analysis

Background

Gastric cancer (GC) is considered one of the most lethal malignancies worldwide, which is accompanied by a poor prognosis. Although reports regarding the importance of cancer stem cell (CSC) markers in gastric cancer progression have rapidly developed over the last few decades, their clinicopathological and prognostic values in gastric cancer still remain inconclusive. Therefore, the current meta-analysis aimed to quantitatively re-evaluate the association of CSC markers expression, overall and individually, with GC patients’ clinical and survival outcomes.

Methods

Literature databases including PubMed, Scopus, ISI Web of Science, and Embase were searched to identify the eligible articles. Hazard ratios (HRs) or odds ratios (ORs) with 95% confidence intervals (CIs) were recorded or calculated to determine the relationships between CSC markers expression positivity and overall survival (OS), disease-free survival (DFS)/relapse-free survival (RFS), disease-specific survival (DSS)/ cancer-specific survival (CSS), and clinicopathological features.

Results

We initially retrieved 4,425 articles, of which a total of 66 articles with 89 studies were considered as eligible for this meta-analysis, comprising of 11,274 GC patients. Overall data analyses indicated that the overexpression of CSC markers is associated with TNM stage (OR = 2.19, 95% CI 1.84–2.61, P = 0.013), lymph node metastasis (OR = 1.76, 95% CI 1.54–2.02, P < 0.001), worse OS (HR = 1.65, 95% CI 1.54–1.77, P < 0.001), poor CSS/DSS (HR = 1.69, 95% CI 1.33–2.15, P < 0.001), and unfavorable DFS/RFS (HR = 2.35, 95% CI 1.90–2.89, P < 0.001) in GC patients. However, CSC markers expression was found to be slightly linked to tumor differentiation (OR = 1.25, 95% CI 1.01–1.55, P = 0.035). Sub-analysis demonstrated a significant positive relationship between most of the individual markers, specially Gli-1, Oct-4, CD44, CD44V6, and CD133, and clinical outcomes as well as the reduced survival, whereas overexpression of Lgr-5, Nanog, and sonic hedgehog (Shh) was not found to be related to the majority of clinical outcomes in GC patients.

Conclusion

The expression of CSC markers is mostly associated with worse outcomes in patients with GC, both overall and individual. The detection of a combined panel of CSC markers might be appropriate as a prognostic stratification marker to predict tumor aggressiveness and poor prognosis in patients with GC, which probably results in identifying novel potential targets for therapeutic approaches.

5-Lipoxygenase promotes epithelial-mesenchymal transition through the ERK signaling pathway in gastric cancer

BACKGROUND AND AIM

5-Lipoxygenase has been reported to enhance cell proliferation, migration, and invasion. Epithelial-mesenchymal transition is considered an important process for tumor metastasis and invasion.

METHODS

The 5-lipoxygenase expression levels and the prognoses in patients with gastric cancer were evaluated by immunohistochemistry and by the log-rank test on Kaplan-Meier curves. We established 5-lipoxygenase-overexpressed and 5-lipoxygenase-silenced gastric cancer cells and measured migration, invasion, and epithelial-mesenchymal transition makers to examine the role of 5-lipoxygenase in gastric cancer in vitro. In vivo, 5-lipoxygenase-overexpressed gastric cancer cells were administered into mice by subcutaneous injection, intraperitoneal injection or splenic intravenous injection to study the proliferation or metastasis of 5-lipoxygenase in mice. Using the extracellular signal-regulated kinase pathway inhibitor U0126 and activator tumor growth factor-β, we investigated the mechanism of epithelial-mesenchymal transition induced by 5-lipoxygenase in gastric cancer cells.

RESULTS

5-Lipoxygenase was upregulated in gastric cancer tissues and was related to poor overall survival in gastric cancer patients. 5-Lipoxygenase promoted gastric cancer cell proliferation, migration, and invasion and induced the process of epithelial-mesenchymal transition in gastric cancer cells. In the nude mouse model, mice with gastric cancer tumors overexpressing 5-LOX had a faster tumor growth rate and more severe abdominal and liver metastases than the control group. Inhibition of extracellular signal-regulated kinase signaling by U0126 or activation by tumor growth factor-β neutralized the effect of 5-LOX overexpression or silencing on epithelial-mesenchymal transition.

CONCLUSION

5-Lipoxygenase promotes epithelial-mesenchymal transition in gastric cancer by activating the extracellular signal-regulated kinase signaling pathway.

Knockdown of TRIM37 Promotes Apoptosis and Suppresses Tumor Growth in Gastric Cancer by Inactivation of the ERK1/2 Pathway

OBJECTIVE

Gastric cancer (GC), a malignant tumor of the gastric mucosa, is the second leading cause of cancer deaths worldwide. Although the incidence and mortality of gastric cancer have been reduced in the US and elsewhere, it is still a major public health concern. In this study, we attempted to investigate the function of tripartite motif-containing protein 37 (TRIM37) in GC cell lines in order to propose a new therapy for GC.

METHODS

The expression of TRIM37 in GC patients and cell lines was detected by immunohistochemistry, real-time PCR and Western blotting analysis. After TRIM37 knockdown or overexpression, the cell cycle, proliferation and apoptosis, as well as the expression of related proteins, were detected. In addition, in vivo experiments on nude mice were performed.

RESULTS

We found that TRIM37 expression was significantly elevated in tumor tissues of GC patients and GC cell lines, and patients with high expression of TRIM37 had a poor prognosis. Knockdown of TRIM37 in GC cells significantly inhibited cell proliferation and cell cycle progression, promoted apoptosis, increased cleaved caspase 3 and decreased c-myc and phosphorylation of protein kinase 1/2 (p-ERK1/2). Effects of TRIM37 overexpression were opposite to that of TRIM37 knockdown and were potently attenuated by an ERK1/2 inhibitor. In addition, an ERK1/2 agonist increased TRIM37 and p-ERK1/2 in a dose-dependent manner, and TRIM37 knockdown potently attenuated EGF-induced cell proliferation and expression of TRIM37 and p-ERK1/2. Interestingly, we found that TRIM37 overexpression did not affect the mRNA level of dual-specificity phosphatase 6 (DUSP6), but reduced its protein level in GC cells. Co-immunoprecipitation (Co-IP) analyses revealed that TRIM37 interacted with DUSP6, and TRIM37 overexpression enhanced DUSP6 ubiquitination in GC cells. In vivo experiments on nude mice showed the inhibitory effect of TRIM37 knockdown on tumor growth.

CONCLUSION

These findings suggest that TRIM37 may act as an oncogene in the growth of GC cells and illustrate its potential function as a target in the treatment of GC.

The Role of Sonic Hedgehog Signaling in the Tumor Microenvironment of Oral Squamous Cell Carcinoma

Sonic hedgehog (SHH) and its signaling have been identified in several human cancers, and increased levels of SHH expression appear to correlate with cancer progression. However, the role of SHH in the tumor microenvironment (TME) of oral squamous cell carcinoma (OSCC) is still unclear. No studies have compared the expression of SHH in different subtypes of OSCC and focused on the relationship between the tumor parenchyma and stroma. In this study, we analyzed SHH and expression of its receptor, Patched-1 (PTCH), in the TME of different subtypes of OSCC. Fifteen endophytic-type cases (ED type) and 15 exophytic-type cases (EX type) of OSCC were used. H&E staining, immunohistochemistry (IHC), double IHC, and double-fluorescent IHC were performed on these samples. ED-type parenchyma more strongly expressed both SHH and PTCH than EX-type parenchyma. In OSCC stroma, CD31-positive cancer blood vessels, CD68- and CD11b-positive macrophages, and α-smooth muscle actin-positive cancer-associated fibroblasts partially expressed PTCH. On the other hand, in EX-type stroma, almost no double-positive cells were observed. These results suggest that autocrine effects of SHH induce cancer invasion, and paracrine effects of SHH govern parenchyma-stromal interactions of OSCC. The role of the SHH pathway is to promote growth and invasion.

Hedgehog Signaling: An Achilles' Heel in Cancer

Hedgehog signaling pathway originally identified in the fruit fly Drosophila is an evolutionarily conserved signaling mechanism with crucial roles in embryogenesis, growth and patterning. It exerts its biological effect through a signaling mechanism that terminates at glioma-associated oncogene (GLI) transcription factors which alternate between activator and repressor forms and mediate various responses. The important components of the pathway include the hedgehog ligands (SHH), the Patched (PTCH) receptor, Smoothened (SMO), Suppressor of Fused (SuFu) and GLI transcription factors. Activating or inactivating mutations in key genes cause uncontrolled activation of the pathway in a ligand independent manner. The ligand-dependent aberrant activation of the hedgehog pathway causing overexpression of hedgehog pathway components and its target genes occurs in autocrine as well as paracrine fashion. In adults, aberrant activation of hedgehog signaling has been linked to birth defects and multiple solid cancers. In this review, we assimilate data from recent studies to understand the mechanism of functioning of the hedgehog signaling pathway, role in cancer, its association in various solid malignancies and the current strategies being used to target this pathway for cancer treatment.

LIFR-AS1 modulates Sufu to inhibit cell proliferation and migration by miR-197-3p in breast cancer

Numerous evidence has recently demonstrated that long non-coding RNAs (lncRNAs) play vital roles in the oncogenesis and development of a wide range of human neoplasms. Leukemia inhibitory factor receptor antisense RNA 1 (LIFR-AS1), a novel cancer-related lncRNA, has been reported to be under-expressed in breast cancer and associated with poor prognosis. However, the exact role of LIFR-AS1 in breast cancer remains largely unclear. The present study aimed to investigate the biological role of LIFR-AS1 in breast cancer and clarify the potential molecular mechanisms. In the present study, we found that LIFR-AS1 was significantly down-regulated in both tissues and cell lines. Furthermore, over-expression of LIFR-AS1 inhibited breast cancer cell proliferation, colony formation, migration and invasion, whereas knockdown of LIFR-AS1 promoted breast cancer cell proliferation, colony formation, migration and invasion. Moreover, LIFR-AS1 was observed to up-regulate suppressor of fused gene (Sufu) expression by competitively binding to miR-197-3p in breast cancer cells. Notably, miR-197-3p inhibitor reversed the promoting effects of LIFR-AS1 knockdown on breast cancer cell proliferation, colony formation, migration and invasion. Additionally, LIFR-AS1 knockdown promoted tumor growth in vivo. To sum up, our results imply the tumor-suppressing role of LIFR-AS1 in breast cancer.

Protective potential of miR-146a-5p and its underlying molecular mechanism in diverse cancers: a comprehensive meta-analysis and bioinformatics analysis

Background/aims

Studies have shown that miR-146a-5p was differentially expressed in diverse cancers, but the associations between miR-146a-5p expression and prognosis across multiple types of cancer as well its potential targets and downstream pathways have not been comprehensively analyzed. In this study, we performed the first meta-analysis of the prognostic value of miR-146a-5p expression in diverse malignancies and explored prospective targets of miR-146a-5p and related signaling pathways.

Methods

A thorough search for articles related to miR-146a-5p was performed, and RNA-seq data from The Cancer Genome Atlas (TCGA) and microarray data from gene expression omnibus profiles were used to collect information about the prognostic value of miR-146a-5p. A comprehensive meta-analysis was conducted. Twelve platforms in miRWalk 2.0 were applied to predict targets of miR-146a-5p. TCGA RNA-seq data were used to validate the inverse relationships between miR-146a-5p and its likely targets. Subsequently, gene ontology and pathway analyses were conducted using Funrich version 3.1.3. Potential protein–protein interaction (PPI) networks were constructed. Potential target genes of miR-146a-5p in lung cancer were validated by RT-qPCR.

Results

We included 10 articles in the meta-analysis. In a pooled analysis, the high miR-146a-5p expression group showed a better overall survival in solid cancers, particularly in reproductive system cancers and digestive system cancers. A total of 120 predicted target genes were included in a bioinformatics analysis. Five pathways involving phospholipase C (PLC) and aquaporins (AQPs) were the most significantly enriched Kyoto Encyclopedia of Genes and Genomes pathways. Moreover, the PPI network displayed the related signaling pathways and interactions among proteins. AQP1 and FYN were validated by RT-qPCR to be potential targets of miR-146a-5p in lung cancer.

Conclusion

There is a close link between high miR-146a-5p expression and better overall survival in 21 types of solid cancer, especially in reproductive system and digestive system cancers. Furthermore, miR-146a-5p could inhibit diverse malignancies by modulating pathways linked to PLC or AQPs. In summary, miR-146a-5p is a potential prognostic biomarker and therapeutic target for various cancers.

Integrin α-3 ß-1's central role in breast cancer, melanoma and glioblastoma cell aggregation revealed by antibodies with blocking activity

Breast cancer, melanoma and glioblastoma cells undergo cell-mediated aggregation and aggregate coalescence in a transparent 3D Matrigel environment. Cells from normal tissue and non-tumorigenic cell lines do not exhibit these behaviors. Here, 266 monoclonal antibodies (mAbs) demonstrated to interact with a wide variety of membrane, secreted and matrix proteins, have been screened for their capacity to block these tumorigenic cell-specific behaviors in a 3D environment. Remarkably, only six of the 266 tested mAbs exhibited blocking activity, four targeting integrin ß-1, one targeting integrin α-3 and one targeting CD44. Colocalization of integrins ß-1 and α-3 in fixed cells and in live aggregates suggests that the integrin α-3 ß-1 dimer plays a central role in cancer cell aggregation in the 3D environment provided by Matrigel. Our results suggest that blocking by anti-integrin and anti-CD44 mAbs involves interference in cell-cell interactions.

Sonic Hedgehog Protein is Frequently Up-Regulated in Pancreatic Cancer Compared to Colorectal Cancer

Sonic hedgehog (SHH) is a secreted protein which functions in autocrine or paracrine fashion on target cells to activate hedgehog (HH) signalling cascade responsible for growth and proliferation. This study is an attempt to understand the expression dynamics of SHH protein in colon, rectal and pancreatic cancers. Protein expression of SHH was studied by Western Blotting in the histologically confirmed colon, rectum and pancreatic cancer tissue samples along with their adjacent normal tissues. Only 31.4% (11 of 35) and 26.9% (7 of 26) of colon and rectal cancer cases respectively showed an increase in SHH expression in tumours compared to 72.7% (24 of 33) of the pancreatic cancer cases when compared with their adjacent normal tissues. Our results suggest that SHH may have a strong role in the predisposition of Pancreatic cancer and could possibly be used as a diagnostic or prognostic biomarker.

Sonic Hedgehog Signaling Pathway Mediates Proliferation and Migration of Fibroblast-Like Synoviocytes in Rheumatoid Arthritis via MAPK/ERK Signaling Pathway

Fibroblast-like synoviocytes (FLSs) are the major effector cells that lead to rheumatoid arthritis (RA) synovitis and joint destruction. Our previous studies showed that Sonic Hedgehog (SHH) signaling pathway is involved in aberrant activation of RA-FLSs and inhibition of SHH pathway decreases proliferation and migration of RA-FLSs. The objective of this study was to investigate if the SHH pathway mediates proliferation and migration of RA-FLSs via the mitogen-activated protein kinases/extracellular signal-regulated kinases (MAPK/ERK) signaling pathway. SHH signaling was studied by using SHH agonist (Purmorphamine) and antagonist (Cyclopamine) targeting the Smoothened (SMO) in FLSs. U0126-EtOH was used to inhibit the MAPK/ERK signaling pathway. The phosphorylation of ERK 1/2 (p-ERKl/2) was examined by western blot. Cell viability was detected using cell proliferation and cytotoxicity kit-8 (CCK8), and cell cycle distribution and proliferating cells were evaluated by the flow cytometry. Cell migration was examined by Transwell assay. Results showed that, compared with the control group, Purmorphamine increased the levels of p-ERK1/2 in concentration-and time-dependent manners (P < 0.01). Co-treated with Purmorphamine and U0126-EtOH or Cyclopamine both decreased the levels of p-ERK1/2 (P < 0.05). RA-FLSs treated with Purmorphamine resulted in alteration of cell cycle distribution, increasing of proliferating cells, cell viability, and migration cells compared to controls (P < 0.01). However, the above phenomenon can be abolished by U0126-EtOH (P < 0.05). The findings suggest that SHH signaling pathway mediates proliferation and migration of RA-FLSs via MAPK/ERK pathway and may contribute to progression of RA. Targeting SHH signaling may have a therapeutic potential in patients with RA.

IL-17A-mediated ERK1/2/p65 signaling pathway is associated with cell apoptosis after non-alcoholic steatohepatitis

Interleukin (IL)-17A is pro-inflammatory cytokine which has been identified as a noninvasive marker of the pathogenesis of non-alcoholic steatohepatitis (NASH). However, the underlying role of IL-17A in NASH progression remains unclear. This study was designed to investigate the biological function and molecular mechanism of IL-17A in the induction of NASH. The results showed that IL-17A was highly expressed in high-fat diet (HFD)-induced NASH mouse model. Intravenous injection of IL-17A exacerbated steatohepatitis process via promoting hepatocyte apoptosis. Furthermore, IL-17A-induced apoptosis was mediated by ERK1/2/p65 signaling pathway. In conclusion, we demonstrated that IL-17A-mediated ERK1/2/p65 signaling pathway was a promising target for the treatment of NASH. © 2018 IUBMB Life, 71(3):302-309, 2019.

The E3 ubiquitin ligase UBR5 regulates centriolar satellite stability and primary cilia

Primary cilia are crucial for signal transduction in a variety of pathways, including hedgehog and Wnt. Disruption of primary cilia formation (ciliogenesis) is linked to numerous developmental disorders (known as ciliopathies) and diseases, including cancer. The ubiquitin-proteasome system (UPS) component UBR5 was previously identified as a putative positive regulator of ciliogenesis in a functional genomics screen. UBR5 is an E3 ubiquitin ligase that is frequently deregulated in tumors, but its biological role in cancer is largely uncharacterized, partly due to a lack of understanding of interacting proteins and pathways. We validated the effect of UBR5 depletion on primary cilia formation using a robust model of ciliogenesis, and identified CSPP1, a centrosomal and ciliary protein required for cilia formation, as a UBR5-interacting protein. We show that UBR5 ubiquitylates CSPP1, and that UBR5 is required for cytoplasmic organization of CSPP1-comprising centriolar satellites in centrosomal periphery, suggesting that UBR5-mediated ubiquitylation of CSPP1 or associated centriolar satellite constituents is one underlying requirement for cilia expression. Hence, we have established a key role for UBR5 in ciliogenesis that may have important implications in understanding cancer pathophysiology.

Targeting GLI Transcription Factors in Cancer

Aberrant activation of hedgehog (Hh) signaling has been observed in a wide variety of tumors and accounts for more than 25% of human cancer deaths. Inhibitors targeting the Hh signal transducer Smoothened (SMO) are widely used and display a good initial efficacy in patients suffering from basal cell carcinoma (BCC); however, a large number of patients relapse. Though SMO mutations may explain acquired therapy resistance, a growing body of evidence suggests that the non-canonical, SMO-independent activation of the Hh pathway in BCC patients can also account for this adverse effect. In this review, we highlight the importance of glioma-associated oncogene (GLI) transcription factors (the main downstream effectors of the canonical and the non-canonical Hh cascade) and their putative role in the regulation of multiple oncogenic signaling pathways. Moreover, we discuss the contribution of the Hh signaling to malignant transformation and propose GLIs as central hubs in tumor signaling networks and thus attractive molecular targets in anti-cancer therapies.

Inhibition of Hedgehog signaling suppresses proliferation and microcyst formation of human Autosomal Dominant Polycystic Kidney Disease cells

Autosomal Dominant Polycystic Kidney Disease (ADPKD) is caused by mutation of PKD1 or PKD2, which encode polycystin 1 and 2, respectively. The polycystins localize to primary cilia and the functional loss of the polycystin complex leads to the formation and progressive growth of fluid-filled cysts in the kidney. The pathogenesis of ADPKD is complex and molecular mechanisms connecting ciliary dysfunction to renal cystogenesis are unclear. Primary cilia mediate Hedgehog signaling, which modulates cell proliferation and differentiation in a tissue-dependent manner. Previously, we showed that Hedgehog signaling was increased in cystic kidneys of several PKD mouse models and that Hedgehog inhibition prevented cyst formation in embryonic PKD mouse kidneys treated with cAMP. Here, we show that in human ADPKD tissue, Hedgehog target and activator, Glioma 1, was elevated and localized to cyst-lining epithelial cells and to interstitial cells, suggesting increased autocrine and paracrine Hedgehog signaling in ADPKD, respectively. Further, Hedgehog inhibitors reduced basal and cAMP-induced proliferation of ADPKD cells and cyst formation in vitro. These data suggest that Hedgehog signaling is increased in human ADPKD and that suppression of Hedgehog signaling can counter cellular processes that promote cyst growth in vitro.

Old Sonic Hedgehog, new tricks: a new paradigm in thoracic malignancies

The Sonic Hedgehog (Shh) pathway is physiologically involved during embryogenesis, but is also activated in several diseases, including solid cancers. Previous studies have demonstrated that the Shh pathway is involved in oncogenesis, tumor progression and chemoresistance in lung cancer and mesothelioma. The Shh pathway is also closely associated with epithelial-mesenchymal transition and cancer stem cells. Recent findings have revealed that a small proportion of lung cancer cells expressed an abnormal full-length Shh protein, associated with cancer stem cell features. In this paper, we review the role of the Shh pathway in thoracic cancers (small cell lung cancer, non-small cell lung cancer, and mesothelioma) and discuss the new perspectives of cancer research highlighted by the recent data of the literature.

Identification of novel therapeutic target genes and pathway in pancreatic cancer by integrative analysis

BACKGROUND

Gene alterations are crucial to the molecular pathogenesis of pancreatic cancer. The present study was designed to identify the potential candidate genes in the pancreatic carcinogenesis.

METHODS

Gene Expression Omnibus database (GEO) datasets of pancreatic cancer tissue were retrieval and the differentially expressed genes (DEGs) from individual microarray data were merged. Gene Ontology (GO) enrichment analysis, Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis, protein-protein interaction (PPI) networks, and gene coexpression analysis were performed.

RESULTS

Three GEO datasets, including 74 pancreatic cancer samples and 55 controls samples were selected. A total of 2325 DEGs were identified, including 1383 upregulated and 942 downregulated genes. The GO terms for molecular functions, biological processes, and cellular component were protein binding, small molecule metabolic process, and integral to membrane, respectively. The most significant pathway in KEGG analysis was metabolic pathways. PPI network analysis indicated that the significant hub genes including cytochrome P450, family 2, subfamily E, polypeptide 1 (CYP2E1), mitogen-activated protein kinase 3 (MAPK3), and phospholipase C, gamma 1 (PLCG1). Gene coexpression network analysis identified 4 major modules, and the potassium channel tetramerization domain containing 10 (KCTD10), kin of IRRE like (KIRREL), dipeptidyl-peptidase 10 (DPP10), and unc-80 homolog (UNC80) were the hub gene of each modules, respectively.

CONCLUSION

Our integrative analysis provides a comprehensive view of gene expression patterns associated with the pancreatic carcinogenesis.

Antagonism between Hedgehog and Wnt signaling pathways regulates tumorigenicity

The crosstalk of multiple cellular signaling pathways is crucial in animal development and tissue homeostasis, and its dysregulation may result in tumor formation and metastasis. The Hedgehog (Hh) and Wnt signaling pathways are both considered to be essential regulators of cell proliferation, differentiation and oncogenesis. Recent studies have indicated that the Hh and Wnt signaling pathways are closely associated and involved in regulating embryogenesis and cellular differentiation. Hh signaling acts upstream of the Wnt signaling pathway, and negative regulates Wnt activity via secreted frizzled-related protein 1 (SFRP1), and the Wnt/β-catenin pathway downregulates Hh activity through glioma-associated oncogene homolog 3 transcriptional regulation. This evidence suggests that the imbalance of Hh and Wnt regulation serves a crucial role in cancer-associated processes. The activation of SFRP1, which inhibits Wnt, has been demonstrated to be an important cross-point between the two signaling pathways. The present study reviews the complex interaction between the Hh and Wnt signaling pathways in embryogenesis and tumorigenicity, and the role of SFRP1 as an important mediator associated with the dysregulation of the Hh and Wnt signaling pathways.

Human CAFs promote lymphangiogenesis in ovarian cancer via the Hh-VEGF-C signaling axis

Cancer-associated fibroblasts (CAFs) play a pivotal role in the development and progression of many human cancers. Recent studies have shown that Hedgehog (Hh) signalling modulates the stromal microenvironment and prepares a suitable niche for tumour metastasis. However, the detailed molecular mechanisms underlying CAF-mediated lymphangiogenesis have not been fully elucidated. Therefore, our goal is to illustrate whether Hh ligands can activate Hh signalling in CAFs in a paracrine fashion and elucidate the effect of CAFs on lymphangiogenesis. We determined here that Sonic Hedgehog (SHH) secreted by ovarian cancer (OC) cells activated Hh signalling in CAFs and promoted the proliferation of CAFs. Moreover, we co-injected SHH-overexpressing OC cells and CAFs in a xenograft model and found that the CAFs accelerated tumourigenesis and lymphangiogenesis in OC. Mechanistically, we found that SHH secreted by the OC cells induced VEGF-C expression in CAFs. Inhibition of Hh signalling in CAFs decreased VEGF-C expression and diminished the positive role of CAFs in supporting tumourigenesis and lymphangiogenesis in a murine xenograft model. Our results demonstrate that CAFs constitute a supportive niche for cancer lymphangiogenesis via the Hh/VEGF-C signalling axis and provide evidence for the clinical application of Hh inhibitors in the treatment of OC.

Breast Cancer Stem Cell Therapeutics, Multiple Strategies Versus Using Engineered Mesenchymal Stem Cells With Notch Inhibitory Properties: Possibilities and Perspectives

Relapse cases of cancers are more vigorous and difficult to control due to the preponderance of cancer stem cells (CSCs). Such CSCs that had been otherwise dormant during the first incidence of cancer gradually appear as radiochemoresistant cancer cells. Hence, cancer therapeutics aimed at CSCs would be an effective strategy for mitigating the cancers during relapse. Alternatively, CSC therapy can also be proposed as an adjuvant therapy, along-with the conventional therapies. As regenerative stem cells (RSCs) are known for their trophic effects, anti-tumorogenicity, and better migration toward an injury site, this review aims to address the use of adult stem cells such as dental pulp derived; cord blood derived pure populations of regenerative stem cells for targeting CSCs. Indeed, pro-tumorogenicity of RSCs is of concern and hence has also been dealt with in relation to breast CSC therapeutics. Furthermore, as notch signaling pathways are upregulated in breast cancers, and anti-notch antibody based and sh-RNA based therapies are already in the market, this review focuses the possibilities of engineering RSCs to express notch inhibitory proteins for breast CSC therapeutics. Also, we have drawn a comparison among various possibilities of breast CSC therapeutics, about, notch1 inhibition. J. Cell. Biochem. 119: 141-149, 2018. © 2017 Wiley Periodicals, Inc.

Opposing effects of prostaglandin E2 receptors EP3 and EP4 on mouse and human β-cell survival and proliferation

OBJECTIVE

Hyperglycemia and systemic inflammation, hallmarks of Type 2 Diabetes (T2D), can induce the production of the inflammatory signaling molecule Prostaglandin E₂ (PGE₂) in islets. The effects of PGE₂ are mediated by its four receptors, E-Prostanoid Receptors 1-4 (EP1-4). EP3 and EP4 play opposing roles in many cell types due to signaling through different G proteins, G_i and G_S, respectively. We previously found that EP3 and EP4 expression are reciprocally regulated by activation of the FoxM1 transcription factor, which promotes β-cell proliferation and survival. Our goal was to determine if EP3 and EP4 regulate β-cell proliferation and survival and, if so, to elucidate the downstream signaling mechanisms.

METHODS

β-cell proliferation was assessed in mouse and human islets ex vivo treated with selective agonists and antagonists for EP3 (sulprostone and DG-041, respectively) and EP4 (CAY10598 and L-161,982, respectively). β-cell survival was measured in mouse and human islets treated with the EP3- and EP4-selective ligands in conjunction with a cytokine cocktail to induce cell death. Changes in gene expression and protein phosphorylation were analyzed in response to modulation of EP3 and EP4 activity in mouse islets.

RESULTS

Blockade of EP3 enhanced β-cell proliferation in young, but not old, mouse islets in part through phospholipase C (PLC)-γ1 activity. Blocking EP3 also increased human β-cell proliferation. EP4 modulation had no effect on ex vivo proliferation alone. However, blockade of EP3 in combination with activation of EP4 enhanced human, but not mouse, β-cell proliferation. In both mouse and human islets, EP3 blockade or EP4 activation enhanced β-cell survival in the presence of cytokines. EP4 acts in a protein kinase A (PKA)-dependent manner to increase mouse β-cell survival. In addition, the positive effects of FoxM1 activation on β-cell survival are inhibited by EP3 and dependent on EP4 signaling.

CONCLUSIONS

Our results identify EP3 and EP4 as novel regulators of β-cell proliferation and survival in mouse and human islets ex vivo.

Overexpression of Aristaless-Like Homeobox-4 Inhibits Proliferation, Invasion, and EMT in Hepatocellular Carcinoma Cells

Aristaless-like homeobox-4 (ALX4), a member of the Aristaless-like homeobox family, has been found to be involved in tumor cell proliferation, migration, and invasion. However, the role of ALX4 in hepatocellular carcinoma (HCC) remains largely unclear. Therefore, in this study we investigated the effects of ALX4 on HCC. The study results indicated that the expression of ALX4 was downregulated in HCC tissues and cell lines. Furthermore, we demonstrated that overexpression of ALX4 inhibited the proliferation, invasion, and epithelial–mesenchymal transition (EMT) in HCC cells. We also found that ALX4 had an inhibitory effect on the sonic hedgehog (Shh) signaling pathway. Taken together, the results suggest that ALX4 may be a promising target for HCC treatment.

Melanoma cells undergo aggressive coalescence in a 3D Matrigel model that is repressed by anti-CD44

Using unique computer-assisted 3D reconstruction software, it was previously demonstrated that tumorigenic cell lines derived from breast tumors, when seeded in a 3D Matrigel model, grew as clonal aggregates which, after approximately 100 hours, underwent coalescence mediated by specialized cells, eventually forming a highly structured large spheroid. Non-tumorigenic cells did not undergo coalescence. Because histological sections of melanomas forming in patients suggest that melanoma cells migrate and coalesce to form tumors, we tested whether they also underwent coalescence in a 3D Matrigel model. Melanoma cells exiting fragments of three independent melanomas or from secondary cultures derived from them, and cells from the melanoma line HTB-66, all underwent coalescence mediated by specialized cells in the 3D model. Normal melanocytes did not. However, coalescence of melanoma cells differed from that of breast-derived tumorigenic cell lines in that they 1) coalesced immediately, 2) underwent coalescence as individual cells as well as aggregates, 3) underwent coalescence far faster and 4) ultimately formed long, flat, fenestrated aggregates that were extremely dynamic. A screen of 51 purified monoclonal antibodies (mAbs) targeting cell surface-associated molecules revealed that two mAbs, anti-beta 1 integrin/(CD29) and anti-CD44, blocked melanoma cell coalescence. They also blocked coalescence of tumorigenic cells derived from a breast tumor. These results add weight to the commonality of coalescence as a characteristic of tumorigenic cells, as well as the usefulness of the 3D Matrigel model and software for both investigating the mechanisms regulating tumorigenesis and screening for potential anti-tumorigenesis mAbs.

Overexpression of SCUBE2 Inhibits Proliferation, Migration, and Invasion in Glioma Cells

Signal peptide CUB EGF-like domain-containing protein 2 (SCUBE2), a member of the SCUBE family of proteins, was recently found to play an important role in cancer development. However, little is known regarding its biological function in glioma. In the present study, we investigated the effect of SCUBE2 on glioma and explored its relevant mechanisms. The study showed that SCUBE2 had a low expression in glioma tissue and cell lines. SCUBE2 overexpression inhibited glioma cell proliferation in vitro and in vivo as well as suppressed glioma cell migration and invasion in vitro. Furthermore, we found that the Sonic hedgehog (Shh) signaling pathway was involved in the inhibitory effect of SCUBE2 overexpression on glioma cells. In light of the results obtained from our study, SCUBE2 may be regarded as a potential therapeutic target for glioma.

Targeting EP4 downstream c-Jun through ERK1/2-mediated reduction of DNMT1 reveals novel mechanism of solamargine-inhibited growth of lung cancer cells

Lung cancer is the most common cancer and the leading cause of cancer deaths worldwide. We previously showed that solamargine, one natural phytochemicals from traditional plants, inhibited the growth of lung cancer cells through inhibition of prostaglandin E2 (PGE₂ ) receptor EP4. However, the potential downstream effectors of EP4 involving in the anti-lung cancer effects of solamargine still remained to be determined. In this study, we further verified that solamargine inhibited growth of non-small-cell lung cancer (NSCLC) cells in multiple cell lines. Mechanistically, solamargine increased phosphorylation of ERK1/2. Moreover, solamargine inhibited the protein expression of DNA methyltransferase 1 (DNMT1) and c-Jun, which were abrogated in cells treated with MEK/ERK1/2 inhibitor (PD98059) and transfected with exogenously expressed DNMT1 gene, respectively. Interestingly, overexpressed DNMT1 gene antagonized the effect of solamargine on c-Jun protein expression. Intriguingly, overexpressed c-Jun blocked solamargine-inhibited lung cancer cell growth, and feedback resisted the solamargine-induced phosphorylation of ERK1/2. A nude mouse xenograft model implanted with lung cancer cells in vivo confirmed the results in vitro. Collectively, our results show that solamargine inhibits the growth of human lung cancer cells through reduction of EP4 protein expression, followed by increasing ERK1/2 phosphorylation. This results in decrease in DNMT1 and c-Jun protein expressions. The inter-correlations between EP4, DNMT1 and c-Jun and feedback regulation of ERK1/2 by c-Jun contribute to the overall responses of solamargine in this process. This study uncovers an additional novel mechanism by which solamargine inhibits growth of human lung cancer cells.