Erbin loss promotes cancer cell proliferation through feedback activation of Akt-Skp2-p27 signaling

Identifying Candidate Genes Associated with Sporadic Amyotrophic Lateral Sclerosis via Integrative Analysis of Transcriptome-Wide Association Study and Messenger RNA Expression Profile

Amyotrophic lateral sclerosis, a fatal neurodegeneration disease affecting motor neurons in the brain and spinal cord, is difficult to diagnose and treat. The objective of this study is to identify novel candidate genes related to ALS. Transcriptome-wide association study of ALS was conducted by integrating the genome-wide association study summary data (including 1234 ALS patients and 2850 controls) and pre-computed gene expression weights of different tissues. The ALS-associated genes identified by TWAS were further compared with the differentially expressed genes detected by the mRNA expression profiles of the sporadic ALS. Functional enrichment and annotation analysis of identified genes were performed by an R package and the functional mapping and annotation software. TWAS identified 761 significant genes (P_TWAS < 0.05), 627 Gene ontology terms, and 8 Kyoto Encyclopedia of Genes and Genomes pathways for ALS, such as C9orf72, with three expression quantitative trait loci were found significantly: rs2453554 (P_{TWAS CBRS} = 4.68 × 10^-10, P_{TWAS CBRS} = 2.54 × 10^-9), rs10967976 (P_{TWAS CBRS} = 7.85 × 10^-10, P_{TWAS CBRS} = 8.91 × 10^-9, P_{TWAS CBRS} = 1.49 × 10^-7, P_{TWAS CBRS} = 5.59 × 10^-7), rs3849946 (P_{TWAS CBRS} = 7.69 × 10^-4, P_{TWAS YBL} = 4.02 × 10^-2), Mitochondrion (P_adj = 4.22 × 10^-16), and Cell cycle (P_adj = 2.04 × 10^-3). Moreover, 107 common genes, 4 KEGG pathways and 41 GO terms were detected by integrating mRNA expression profiles of sALS, such as CPVL (FC = 2.06, P_mRNA = 6.99 × 10^-6, P_{TWAS CBR} = 2.88 × 10^-2, P_{TWAS CBR} = 4.37 × 10^-2), Pyrimidine Metabolism (P_adj = 2.43 × 10^-2), and Cell Activation (P_adj = 5.54 × 10^-3). Multiple candidate genes and pathways were detected for ALS. Our findings may provide novel clues for understanding the genetic mechanism of ALS.

The single-sample network module biomarkers (sNMB) method reveals the pre-deterioration stage of disease progression

The progression of complex diseases generally involves a pre-deterioration stage that occurs during the transition from a healthy state to disease deterioration, at which a drastic and qualitative shift occurs. The development of an effective approach is urgently needed to identify such a pre-deterioration stage or critical state just before disease deterioration, which allows the timely implementation of appropriate measures to prevent a catastrophic transition. However, identifying the pre-deterioration stage is a challenging task in clinical medicine, especially when only a single sample is available for most patients, which is responsible for the failure of most statistical methods. In this study, a novel computational method, called single-sample network module biomarkers (sNMB), is presented to predict the pre-deterioration stage or critical point using only a single sample. Specifically, the proposed single-sample index effectively quantifies the disturbance caused by a single sample against a group of given reference samples. Our method successfully detected the early warning signal of the critical transitions when applied to both a numerical simulation and four real datasets, including acute lung injury, stomach adenocarcinoma, esophageal carcinoma, and rectum adenocarcinoma. In addition, it provides signaling biomarkers for further practical application, which helps to discover prognostic indicators and reveal the underlying molecular mechanisms of disease progression.

HSP70 promotes tumor progression by stabilizing Skp2 expression in gastric cancer cells

Gastric cancer (GC) has one of the highest tumor incidences worldwide. Heat shock protein 70 (HSP70) is highly expressed and plays a critical role in the occurrence, progression, metastasis, poor prognosis, and drug resistance of GC. However, the underlying mechanisms of HSP70 are not clear. To explore the regulatory role of HSP70 in GC, we performed cell counting kit-8 (CCK-8) and EdU staining assays to assess cell proliferation; immunohistochemistry and western blot analyses to assess protein expression; coimmunoprecipitation (Co-IP) assays to assess interactions between two proteins; and immunofluorescence to assess protein expression and localization. HSP70 was highly expressed in clinical samples from patients with GC and indicated a poor prognosis. HSP70 inhibition enhanced the sensitivity of GC cells to thermochemotherapy. Furthermore, we found that S phase kinase-associated protein 2 (Skp2) was highly expressed in GC and correlated with HSP70 in array data from The Cancer Genome Atlas (TCGA). Importantly, HSP70 inhibition promoted Skp2 degradation. Skp2 overexpression abrogated HSP70 inhibition-induced cell cycle arrest, suggesting that the role of HSP70 in GC depends on Skp2 expression. Our results illustrate a possible regulatory mechanism of HSP70 and may provide a therapeutic strategy for overcoming resistance to thermochemotherapy.

Reduced IκBα promotes hepatocellular carcinoma cell proliferation and migration via regulation of NF-κB/Erbin axis

Aberrantly low expression of NF-κB inhibitor α (IκBα) is observed in hepatocellular carcinoma (HCC), yet the underlying mechanism via which IκBα regulates HCC remains largely unknown. Therefore, to determine the potential function of IκBα in hepatocarcinogenesis, the present study used immunohistochemistry (IHC) staining to analyze the associations between IκBα protein expression and clinicopathologic characteristics of 107 patients with HCC. It was found that expression of IκBα was significantly associated with tumor recurrence. Moreover, IκBα protein expression was decreased in 107 HCC tissue samples and was positively associated with overall survival. Mechanistically, it was demonstrated that silencing of IκBα activated NF-κB in both Huh7 and HCCLM3 cells, followed by upregulation of Erbb2 interacting protein (Erbin) at both the mRNA and protein levels, confirmed by reverse transcription-quantitative PCR and western blotting, to promote cell proliferation and migration. Furthermore, knockdown of Erbin significantly attenuated NF-κB-mediated cell proliferation and migration. It was also identified that overexpression of Erbin in HCC tissues promoted both cell proliferation and migration, and was negatively associated with IκBα expression in 107 HCC tissue samples. Thus, these results indicated that downregulation of IκBα promoted HCC tumorigenesis via upregulation of NF-κB-mediated Erbin expression.

The leucine-rich repeat signaling scaffolds Shoc2 and Erbin: cellular mechanism and role in disease

Leucine-rich repeat-containing proteins (LRR proteins) are involved in supporting a large number of cellular functions. In this review, we summarize recent advancements in understanding functions of the LRR proteins as signaling scaffolds. In particular, we explore what we have learned about the mechanisms of action of the LRR scaffolds Shoc2 and Erbin and their roles in normal development and disease. We discuss Shoc2 and Erbin in the context of their multiple known interacting partners in various cellular processes and summarize often unexpected functions of these proteins through analysis of their roles in human pathologies. We also review these LRR scaffold proteins as promising therapeutic targets and biomarkers with potential application across various pathologies.

The Scribble family in cancer: twentieth anniversary

Among the more than 160 PDZ containing proteins described in humans, the cytoplasmic scaffold Scribble stands out because of its essential role in many steps of cancer development and dissemination. Its fame has somehow blurred the importance of homologous proteins, Erbin and Lano, all belonging to the LRR and PDZ (LAP) protein family first described twenty years ago. In this review, we will retrace the history of LAP family protein research and draw attention to their contribution in cancer by detailing the features of its members at the structural and functional levels, and highlighting their shared-but also different-implication in the tumoral process.

Delivery of mesenchymal stem cells-derived extracellular vesicles with enriched miR-185 inhibits progression of OPMD

Oral leukoplakia is one of the most common oral potentially malignant disorders (OPMDs) and its malignant transformation to oral cancer is highly associated with chronic inflammation. Extracellular vesicles (EVs) or exosome-delivered microRNAs modulate inflammatory responses and alleviate irritations that predisposes to cancer. We previously reported that microRNA-185 (miR-185) was significantly decreased in the buccal tissue of patients with oral cancer. In this study, we utilized genetically modified mesenchymal stem cells (MSCs) derived EVs with high expression of miR-185 to pasted MSC-EV-miR-185 on buccal lesions in dimethylbenzanthracene (DMBA) induced OPMD model. We found that treatment with MSC-EV-miR-185 remarkably attenuated inflammation severity and significantly decreased the incidence and the number of dysplasia in the OPMD tissue. Immunohistochemistry showed significantly decreased expression of proliferation marker PCNA and angiogenic marker CD31 in the lesion treated with MSC-EV-miR-185. Furthermore, miR-185 specifically targeted Akt genes by promoting activation of the apoptotic pathway, confirmed by the increased levels of activated caspase-3 and 9. In conclusion, genetically modified MSC-derived EVs enriched with miR-185 alleviate inflammatory response, inhibit cell proliferation and angiogenesis, and induce cell apoptosis, suggesting that their potential role as a novel therapeutic option for OPMD.

Desmoglein 1 Regulates Invadopodia by Suppressing EGFR/Erk Signaling in an Erbin-Dependent Manner

Loss of the desmosomal cell-cell adhesion molecule, Desmoglein 1 (Dsg1), has been reported as an indicator of poor prognosis in head and neck squamous cell carcinomas (HNSCC) overexpressing epidermal growth factor receptor (EGFR). It has been well established that EGFR signaling promotes the formation of invadopodia, actin-based protrusions formed by cancer cells to facilitate invasion and metastasis, by activating pathways leading to actin polymerization and ultimately matrix degradation. We previously showed that Dsg1 downregulates EGFR/Erk signaling by interacting with the ErbB2-binding protein Erbin (ErbB2 Interacting Protein) to promote keratinocyte differentiation. Here, we provide evidence that restoring Dsg1 expression in cells derived from HNSCC suppresses invasion by decreasing the number of invadopodia and matrix degradation. Moreover, Dsg1 requires Erbin to downregulate EGFR/Erk signaling and to fully suppress invadopodia formation. Our findings indicate a novel role for Dsg1 in the regulation of invadopodia signaling and provide potential new targets for development of therapies to prevent invadopodia formation and therefore cancer invasion and metastasis. IMPLICATIONS: Our work exposes a new pathway by which a desmosomal cadherin called Dsg1, which is lost early in head and neck cancer progression, suppresses cancer cell invadopodia formation by scaffolding ErbB2 Interacting Protein and consequent attenuation of EGF/Erk signaling.

Erbin plays a critical role in human umbilical vein endothelial cell migration and tubular structure formation via the Smad1/5 pathway

Angiogenesis is an important process in atherosclerosis. ErbB2 was proved to have an important role in vascular development, but it is still unclear whether Erbin expresses in vessels as well as its location and function in the vessels. In the current study, we investigated the location and function of Erbin in human umbilical veins. The human umbilical veins were prepared, and immunofluorescent analysis was performed to determine the expression of Erbin. Human umbilical vein endothelial cells (HUVECs) were cultured and the lentivirus (LV) containing Erbin RNAi was also prepared. After transfection with the lentivirus, CCK-8 assay and Annexin V-PI assay were used for cell proliferation and apoptosis, respectively. Cell migration was studied using the scratch wound healing assay and the transwell assay. The capillary-like tube formation assay was performed to illustrate the effect of Erbin on HUVEC tube formation. Expression of signaling pathway molecules was assessed with Western blot. The immunofluorescent analysis suggested that Erbin expressed in human umbilical veins and the majority of the Erbin is strongly colocalized in endothelial cells. Although knockdown of Erbin did not affect HUVEC proliferation and apoptosis, it significantly suppressed HUVEC migration and tubular structure formation. Erbin knockdown showed no effect on the ERK1/2 and Smad2/3 signaling pathways but significantly promoted Smad1/5 phosphorylation and nuclear translocation. Ablation of the Smad1/5 pathway decreased the effects of Erbin on endothelial cells. Erbin is mainly localized in endothelial cells in human umbilical veins and plays a critical role in endothelial cell migration and tubular formation via the Smad1/5 pathway.

Positive feedback loop of IL-1β/Akt/RARα/Akt signaling mediates oncogenic property of RARα in gastric carcinoma

Abnormal expression and function of retinoic acid receptor α (RARα) have been reported to be associated with various cancers including acute promyelocytic leukemia and hepatocellular carcinoma. However, the role and the mechanism of RARα in gastric carcinoma (GC) were unknown. Here, the expression of RARα was frequently elevated in human GC tissues and cell lines, and its overexpression was closely correlated with tumor size, lymph node metastasis and clinical stages in GC patients. Moreover, RARα overexpression was related with pathological differentiation. Functionally, RARα knockdown inhibited the proliferation and metastasis of GC cells, as well as enhanced drug susceptibility both in vitro and in vivo. Additionally, RARα knockdown suppressed GC progression through regulating the expression of cell proliferation, cell cycle, invasion and drug resistance associated proteins, such as PCNA, CyclinB1, CyclinD2, CyclinE, p21, MMP9 and MDR1. Mechanistically, the above oncogenic properties of RARα in GC were closely associated with Akt signaling activation. Moreover, overexpression of RARα was induced by IL-1β/Akt signaling activation, which suggested a positive feedback loop of IL-1β/Akt/RARα/Akt signaling in GC. Taken together, we demonstrated that RARα was frequently elevated in GC and exerted oncogenic properties. It might be a potential molecular target for GC treatment.

Angiogenesis for tumor vascular normalization of Endostar on hepatoma 22 tumor-bearing mice is involved in the immune response

Tumor vascular normalization involved in immune response is beneficial to the chemotherapy of tumors. Recombinant human endostatin (Endostar), an angiogenesis inhibitor, has been demonstrated to be effective in hepatocellular cancer (HCC). However, its vascular normalization in HCC and the role of the immune response in angiogenesis were unclear. In the present study, effects of Endostar on tumor vascular normalization were evaluated in hepatoma 22 (H22) tumor-bearing mice. Endostar was able to inhibit the proliferation and infiltration of tumor cells and improve α-fetoprotein, tumor necrosis factor-α and cyclic adenosine 5′-phosphate levels in the serum of H22-bearing mice, as well as the protein expression levels of the immune factors interferon-γ and cluster of differentiation (CD)86 in liver tissue. Endostar also exhibited more marked downregulation of the levels of vascular endothelial growth factor, CD31, matrix metalloproteinase (MMP)-2, MMP-9 and interleukin-17 during day 3–9 treatment, resulting in short-term normalization of tumor blood vessels. The period of vascular normalization was 3–9 days. The results of the present study demonstrated that Endostar was able to induce the period of vascular normalization, contributing to a more efficacious means of HCC treatment combined with other chemotherapy, and this effect was associated with the immune response. It may be concluded that Endostar inhibited immunity-associated angiogenesis behaviors of vascular endothelial cells in response to HCC. The results of the present study provided more reasonable possibility for the combination therapy of Endostar for the treatment of HCC.

Elevated expression of Erbin destabilizes ERα protein and promotes tumorigenesis in hepatocellular carcinoma

BACKGROUND & AIMS

Aberrant estrogen receptor-α (ERα) expression and signaling are implicated in the development of hepatocellular carcinoma (HCC), but its regulation in HCC remains enigmatic. Herein, we aimed to identify a new mechanism by which ERα signaling is regulated in HCC, which may lead to a potential new strategy for HCC therapy.

METHODS

Expression levels of Erbin and ERα in human HCC samples were evaluated by immunohistochemistry. In vitro and in vivo experiments were used to assess the effect of Erbin and ERα signaling on HCC cell growth. Crosstalk between Erbin and ERα signaling was analyzed by molecular methods. Animal models of diethylnitrosamine (DEN) or DEN/CCl₄-induced HCC in wild-type Erbin^+/+ and mutant Erbin^ΔC/ΔC mice were observed. The regulatory effects of Erbin on tamoxifen treatment of HCC were evaluated in vitro and in vivo.

RESULTS

Erbin inactivated ERα signaling to drive tumorigenesis of HCC, acting to enhance binding of Chip to ERα via its interaction with ERα and thereby promoting ubiquitination and degradation of ERα. Deletion of the PDZ domain of Erbin in Erbin^ΔC/ΔC mice, disrupted the interaction of Chip and ERα, increased the stability of ERα protein, and thus inhibited tumorigenesis of HCC. Silencing of Erbin effectively sensitized the response of HCC after tamoxifen treatment in vitro and in vivo.

CONCLUSIONS

Our data uncovered an important role of Erbin in regulating HCC tumorigenesis through inactivating ERα-mediated tumor-suppressive signaling, suggesting a new strategy for tamoxifen therapy in HCC by targeting Erbin/ERα signaling axis.

LAY SUMMARY

Erbin expression is significantly elevated in human hepatocellular carcinoma (HCC) tissue. This elevated expression of Erbin contributes to tumorigenesis of HCC by negatively regulating ERα signaling. However, restoring ERα signaling by inhibiting Erbin expression enhances the sensitivity of HCC cells to tamoxifen treatment, providing a new approach for tamoxifen treatment in HCC.

Chinese herbal medicine Fuzheng Kang-Ai decoction sensitized the effect of gefitinib on inhibition of human lung cancer cells through inactivating PI3-K/Akt -mediated suppressing MUC1 expression

ETHNOPHARMACOLOGICAL RELEVANCE

Chinese herbal medicine (CHM) Fuzheng Kang-Ai (FZKA for short) decoction has been used as adjuvant treatment strategies in lung cancer patients for decades. However, the molecular mechanism underlying the therapeutic potential especially in sensitizing the effect of EGFR-TKI gefitinib has not been well elucidated.

MATERIALS AND METHODS

Cell viability was detected by MTT assay. Cell cycle distribution was detected by flow cytometry. Western blot were used to examine phosphorylation and protein levels of Akt, p65, p50 and MUC1. The mRNA level of MUC1 was measured by qRT-PCR. Transient transfection experiments were used to overexpression of Akt, p65 and MUC1. Tumor xenograft and bioluminescent imaging experiments were carried out to confirm the in vitro findings.

RESULTS

Cell viability was inhibited by FZKA treatment and showed more significant when treated with FZKA and gefitinib in combine in lung cancer cells. FZKA induced the cell arrest at G0/G1 phase. Mechanistically, we showed that the phosphorylation of Akt, protein expressions of p65 and MUC1 were suppressed by FZKA and even more responses were observed in the FZKA and gefitinib combining. Overexpressed Akt overcame the effect of FZKA on p65 protein, and exogenously expressed p65 resisted the inhibitory effect of MUC1 protein expression by FZKA. On the contrary, while overexpressed MUC1 had no effect on p65 expression, it feedback increased phosphorylation of Akt, and more importantly, reversed the cell growth inhibition affected by FZKA. In line with the above, our results confirmed the synergistic effects of FZKA and gefitinib combination on tumor growth, the phosphorylation of Akt, and protein expression of p65 and MUC1 in vivo.

CONCLUSION

This study shows that FZKA decoction inhibits the growth of NSCLC cells through Akt-mediated inhibition of p65, followed by reducing the expression of MUC1. More importantly, there is a synergistic effect of FZKA decoction and gefitinib combination with greater suppression. The positive feedback regulatory loop of MUC1 to Akt signaling pathway further added the important role of MUC1 in mediating the overall responses of FZKA decoction in this process. The in vitro and in vivo study provides an additional and a novel mechanism by which the FZKA decoction enhances the growth inhibition of gefitinib in gefitinib-resistant NSCLC cells.

Activation of AMPK α2 inhibits airway smooth muscle cells proliferation

The aims of the present study were to examine the effect of adenosine monophosphate-activated protein kinase (AMPK) activation on airway smooth muscle cells (ASMCs) proliferation and to address its potential mechanisms. Platelet derived growth factor (PDGF) activated phosphatidylinositol 3-kinase (PI3K)/protein kinase B (Akt)/mammalian target of rapamycin (mTOR) signaling pathway, and this in turn up-regulated S-phase kinase-associated protein 2 (Skp2) and consequently reduced cyclin dependent kinase inhibitor 1B (p27) leading to ASMCs proliferation. Pre-incubation of cells with metformin, an AMPK activator, blocked PDGF-induced activation of mTOR and its downstream targets changes of Skp2 and p27 without changing Akt phosphorylation and inhibited ASMCs proliferation. Transfection of ASMCs with AMPK α2-specific small interfering RNA (siRNA) reversed the effect of metformin on mTOR phosphorylation, Skp2 and p27 protein expression and cell proliferation. Our study suggests that activation of AMPK, particularly AMPK α2, negatively regulates mTOR activity to suppress ASMCs proliferation and therefore has a potential value in the prevention and treatment of asthma by negatively modulating airway remodeling.

Inhibiting the role of Skp2 suppresses cell proliferation and tumorigenesis of human gastric cancer cells via the upregulation of p27kip1

Gastric cancer is a malignant disease of the digestive system with high rates of incidence and mortality. S‑phase kinase‑associated protein 2 (Skp2) is a novel oncogene, which has been identified to be important in tumor progression and metastasis. In order to clarify the role of Skp2 in human gastric cancer, the present study detected the expression of Skp2 in human gastric cancer tissues, and investigated the molecular mechanism of Skp2 in the progression of gastric carcinoma. The results of the initial bioinformatics analysis showed that Skp2 was significantly upregulated in 31 specimens of primary gastric cancer from a UK patient cohort, and in 10 gastric cancer lines of a side population, compared with normal gastric tissues (P<0.01). Specimens from 47 patients with gastric cancer and 19 normal gastric tissue specimens were obtained and analyzed using western blot analysis. The positive rate of expression of Skp2 was 87.2%, indicating that the expression of Skp2 was observed in 41 specimens of the detected gastric cancer samples, whereas the positive rate of the expression of Skp2 was 5.6% in the normal gastric samples (P<0.01). In the human gastric cancer cell lines, the defective regulation of Skp2 or presence of an Skp2 inhibitor inhibited the proliferation of BGC‑823 and MKN‑45 cells. In addition, the Skp2 inhibitor suppressed the proliferation of gastric cancer cells in a time‑ and dose‑dependent manner. Furthermore, transfection with Skp2 short hairpin (sh)RNA or treatment with SKP inhibitor C1 for 48 and 72 h led to the accumulation of p27kip1 in Hela cells. Tumorigenicity experiments involving nude mice showed that interference of the expression of Skp2 inhibited the growth of the human gastric tumor cells in the nude mice, and the tumor weights and volumes in the Skp2 shRNA group were significantly lower, compared with those in the negative control shRNA group (P<0.01) and untreated group (P<0.01). Taken together, these data suggested that Skp2 acted as an oncogene in human gastric cancer, and that Skp2‑mediated p27kip1 degradation contributed to the progression of gastric cancer. Abrogating the effects of Skp2 may effectively inhibit the growth of gastric cancer cells, which may be useful as a novel target in the clinical treatment of gastric cancer.

Hydrogen sulfide promotes cell proliferation of oral cancer through activation of the COX2/AKT/ERK1/2 axis

Hydrogen sulfide, the third gaseous transmitter, is one of the main causes of halitosis in the oral cavity. It is generally considered as playing a deleterious role in many oral diseases including oral cancer. However, the regulatory mechanisms involved in the effects of hydrogen sulfide on oral cancer growth remain largely unknown. In the present study, we investigated the underlying mechanisms through CCK-8 assay, EdU incorporation, real-time PCR, western blot and pathway blockade assays. Our results showed that hydrogen sulfide promoted oral cancer cell proliferation through activation of the COX2, AKT and ERK1/2 pathways in a dose-dependent manner. Blocking any of the three above pathways inhibited hydrogen sulfide-induced oral cancer cell proliferation. Meanwhile, blockade of COX2 by niflumic acid downregulated NaHS-induced p-ERK and p-AKT expression. Inactivation of the AKT pathway by GSK690693 significantly decreased NaHS‑induced p-ERK1/2 expression, and inhibition of the ERK1/2 pathway by U0126 markedly increased NaHS-induced p-AKT expression. Either the AKT or ERK1/2 inhibitor did not significantly alter the COX2 expression level. Our data revealed, for the first time, that hydrogen sulfide promotes oral cancer cell proliferation through activation of the COX2/AKT/ERK1/2 axis, suggesting new potential targets to eliminate the effect of hydrogen sulfide on the development of oral cancer.