VCP/p97 targets the nuclear export and degradation of p27Kip1 during G1 to S phase transition

One of the critical regulatory mechanisms for cell cycle progression is the timely degradation of CDK inhibitors, including p21^Cip1 and p27^Kip1 . VCP/p97, an AAA-ATPase, is reported to be overexpressed in many types of cancers. Here, we found that treatment of MCF-7 human breast cancer cells with DBeQ, a VCP inhibitor, or VCP knockdown in MCF-7 cells arrested cells at G1 phase, accompanied with the blockage of both p21 and p27 degradation. Whereas, double knockdown of p21 and p27 in MCF-7 cells rendered cells refractory to DBeQ-induced G1 arrest. Moreover, inhibition or knockdown of VCP or UFD1, one of VCP's co-factors, in MCF-7, NIH3T3, or HEK293T cells blocked the nuclear export of p27 during earlier G1 phase after mitogen stimulation. We also identified the nuclear localization sequence (NLS) of VCP, and found that adding back wild-type VCP, not the NLS-deleted VCP mutant, restored the nuclear export and degradation of p27 in VCP knockout MCF-7 cells. Importantly, we found that VCP inhibition sensitized breast cancer cells to the treatment of several anticancer therapeutics both in vitro and in vivo. Taken together, our study not only uncovers the mechanisms underlying VCP-mediated cell proliferation control but also provides potential therapeutic option for cancer treatment.

Targeting valosin-containing protein enhances the efficacy of radiation therapy in esophageal squamous cell carcinoma

Overcoming resistance to radiation is a great challenge in cancer therapy. Here, we highlight that targeting valosin‐containing protein (VCP) improves radiation sensitivity in esophageal squamous cell carcinoma (ESCC) cell lines and show the potential of using VCP as a prognosis marker in locally advanced ESCC treated with radiation therapy. Esophageal squamous cell carcinoma cell lines with high VCP expression were treated with VCP inhibitor combined with radiotherapy. Cell proliferation, colony formation, cell death, and endoplasmic reticulum (ER) stress signaling were evaluated. Moreover, patients with newly diagnosed locally advanced ESCC who were treated with radiotherapy were analyzed. Immunohistochemistry was used to detect the expression of VCP. The correlation between overall survival and VCP was investigated. Esophageal squamous cell carcinoma cells treated with VCP inhibitor and radiotherapy showed attenuated cell proliferation and colony formation and enhanced apoptosis. Further investigation showed this combined strategy activated the ER stress signaling involved in unfolded protein response, and inhibited the ER‐associated degradation (ERAD) pathway. Clinical analysis revealed a significant survival benefit in the low VCP expression group. Targeting VCP resulted in antitumor activity and enhanced the efficacy of radiation therapy in ESCC cells in vitro. Valosin‐containing protein is a promising and novel target. In patients with locally advanced ESCC who received radiotherapy, VCP can be considered as a useful prognostic indicator of overall survival. Valosin‐containing protein inhibitors could be developed for use as effective cancer therapies, in combination with radiation therapy.

Upregulation of valosin-containing protein (VCP) is associated with poor prognosis and promotes tumor progression of orbital B-cell lymphoma

Objective

This study aimed to investigate the relationship between VCP expression and the prognosis of orbital B-cell lymphoma patients and the influence of downregulation of VCP on the apoptosis and invasion abilities of lymphoma cells.

Methods

We recruited 66 orbital B-cell lymphoma patients. VCP expression in 66 samples of orbital B-cell lymphoma was determined by immunohistochemistry using monoclonal VCP antibodies. Based on VCP-expression levels detected by immunohistochemistry, we chose ten cases of orbital tumor paraffin tissue from the patients. Total RNA was extracted and differences in VCP gene-expression levels compared among patients using quantitative reverse-transcription (qRT) PCR. We used siRNA to knock down VCP in the lymphoma cell lines Raji and SUDHL4. qRT-PCR and Western blot were applied to detect VCP mRNA and protein expression, respectively. SUDHL48 assays were applied to investigate cell proliferation. Hoechst 33258 staining and flow-cytometry analysis were applied to investigate cell apoptosis. Transwell assays were applied to investigate invasive ability. Survival analysis was used to evaluate prognostic values.

Results

Expression levels of VCP were correlated with the stage, tumor grade, and recurrence rate of patients. VCP mRNA-expression levels were consistent with VCP-expression levels in orbital B-cell lymphoma tissue. Moreover, survival analysis revealed that lower VCP-expression levels were correlated with longer overall survival of orbital B-cell lymphoma patients. Down-regulation of VCP with siRNA did not inhibit cell proliferation. However, it dramatically increased apoptosis and suppressed the invasion of B-cell lymphoma cells.

Conclusion

VCP expression played an important role in the progression of orbital B-cell lymphoma. VCP could be a useful marker for predicting the prognosis of orbital B-cell lymphoma patients. VCP may be a potential therapeutic target for orbital B-cell lymphoma.

Discovery of a new class of valosine containing protein (VCP/P97) inhibitors for the treatment of non-small cell lung cancer

Valosine containing protein (VCP/p97) is a member of the AAA ATPase family involved in several essential cellular functions and plays an important role in the ubiquitin-mediated degradation of misfolded proteins. P97 has a significant role in maintaining the cellular protein homeostasis for tumor cell growth and survival and has been found overexpressed in many tumor types. No new molecule entities based on p97 target were approved in clinic. Herein, a series of novel pyrimidine structures as p97 inhibitors were designed and synthesized. After enzymatic evaluations, structure-activity relationships (SAR) were discussed in detailed. Among the screened compounds, derivative 35 showed excellent enzymatic inhibitory activity (IC₅₀, 36 nM). The cellular inhibition results showed that compound 35 had good antiproliferative activity against the non-small cell lung cancer A549 cells (IC₅₀, 1.61 μM). Liver microsome stability showed that the half-life of compound 35 in human liver microsome was 42.3 min, which was more stable than the control CB-5083 (25.8 min). The in vivo pharmacokinetic results showed that the elimination phase half-lives of compound 35 were 4.57 h for ig and 3.64 h for iv, respectively and the oral bioavailability was only 4.5%. These results indicated that compound 35 could be effective for intravenous treatment of non-small cell lung cancer.

Osteoprotegerin rich tumor microenvironment: implications in breast cancer

Osteoprotegerin (OPG) is a soluble decoy receptor for tumor necrosis factor (TNF)-related apoptosis inducing ligand (TRAIL). It belongs to the tumor necrosis factor receptor superfamily (TNFRSF). OPG was initially discovered to contribute to homeostasis of bone turnover due to its capability of binding to receptor activator of nuclear factor-kappaB (NF-kB). However, apart from bone turnover, OPG plays important and diverse role(s) in many biological functions. Besides having anti-osteoclastic activity, OPG is thought to exert a protective anti-apoptotic action in OPG-expressing tumors by overcoming the physiologic mechanism of tumor surveillance exerted by TRAIL. Along with inhibiting TRAIL induced apoptosis, it can induce proliferation by binding to various cell surface receptors and thus turning on the canonical cell survival and proliferative pathways. OPG also induces angiogenesis, one of the hallmarks of cancer, thus facilitating tumor growth. Recently, the understanding of OPG and its different roles has been augmented substantially. This review is aimed at providing a very informative overview as to how OPG affects cancer progression especially breast cancer.

In vitro efficacy of a first-generation valosin-containing protein inhibitor (CB-5083) against canine lymphoma

Valosin-containing protein (VCP), through its critical role in the maintenance of protein homeostasis, is a promising target for the treatment of several malignancies, including canine lymphoma. CB-5083, a first-in-class VCP inhibitor, exerts cytotoxicity through the induction of irreversible proteotoxic stress and possesses a broad spectrum of anticancer activity. Here, we determined the cytotoxicity CB-5083 in canine lymphoma cells and its mechanism of action in vitro. Canine lymphoma cell lines were treated with varying concentrations of CB-5083 and assessed for viability by trypan blue exclusion and apoptosis by caspase activity assays. The mechanism of CB-5083 action was determined by immunoblotting and RT-qPCR analyses of Lys48 ubiquitination and markers of ER stress (DDIT3), autophagy (SQSTM1, MAP1LC3A) and DNA damage (γH2AX). Unfolded protein response markers were also evaluated by immunoblotting (eIF2α, P-eIF2α) and RT-qPCR (ATF4). CB-5083 treatment resulted in preferential cytotoxicity in canine lymphoma cell lines over control peripheral blood mononuclear cells. CB-5083 rapidly disrupted the ubiquitin-dependent protein degradation system, inducing sustained ER stress as indicated by a dramatic increase in DDIT3. Activation of the unfolded protein response occurred through the increase eIF2α phosphorylation and increased transcription of ATF4, but did not re-establish protein homeostasis. Cells rapidly underwent apoptosis through activation of the caspase cascade. These results further validate VCP as an attractive target for the treatment of canine lymphoma and identify CB-5083 as a novel therapy with clinical potential for this malignancy.

High expression of valosin-containing protein predicts poor prognosis in patients with breast carcinoma

Valosin-containing protein (VCP) is one of the AAA-ATPase superfamily members. The correlation between elevated expression of VCP and progression, prognosis, and the metastatic potential has been identified in various tumor types. However, the clinical impact of VCP in breast carcinoma has not been investigated. In the current study, the expression of VCP in 421 breast tumors and adjacent normal breast tissues was examined to investigate the correlation between VCP expression and clinicopathological features in patients with breast carcinoma. We found that the expression of VCP correlated with the TNM stage, Ki67 labeling, and lymph node metastasis (LNM). The expression of VCP was increased significantly in the cytoplasm of cancer cells compared to normal mammary epithelial cells, which was associated with decreased overall survival rates of patients with breast carcinoma (P < 0.001). In conclusion, this study demonstrates significant correlation between the cytoplasmic expression of VCP and adverse prognosis in breast carcinoma, suggesting that VCP may serve as a prognostic biomarker in breast carcinoma.

Pharmacological targeting of valosin containing protein (VCP) induces DNA damage and selectively kills canine lymphoma cells

Background

Valosin containing protein (VCP) is a critical mediator of protein homeostasis and may represent a valuable therapeutic target for several forms of cancer. Overexpression of VCP occurs in many cancers, and often in a manner correlating with malignancy and poor outcome. Here, we analyzed VCP expression in canine lymphoma and assessed its potential as a therapeutic target for this disease.

Methods

VCP expression in canine lymphomas was evaluated by immunoblotting and immunohistochemistry. The canine lymphoma cell lines CLBL-1, 17–71 and CL-1 were treated with the VCP inhibitor Eeyarestatin 1 (EER-1) at varying concentrations and times and were assessed for viability by trypan blue exclusion, apoptosis by TUNEL and caspase activity assays, and proliferation by propidium iodide incorporation and FACS. The mechanism of EER-1 action was determined by immunoblotting and immunofluorescence analyses of Lys48 ubiquitin and markers of ER stress (DDIT3), autophagy (SQSTM1, MAP1LC3A) and DNA damage (γH2AFX). TRP53/ATM-dependent signaling pathway activity was assessed by immunoblotting for TRP53 and phospho-TRP53 and real-time RT-PCR measurement of Cdkn1a mRNA.

Results

VCP expression levels in canine B cell lymphomas were found to increase with grade. EER-1 treatment killed canine lymphoma cells preferentially over control peripheral blood mononuclear cells. EER-1 treatment of CLBL-1 cells was found to both induce apoptosis and cell cycle arrest in G1. Unexpectedly, EER-1 did not appear to act either by inducing ER stress or inhibiting the aggresome-autophagy pathway. Rather, a rapid and dramatic increase in γH2AFX expression was noted, indicating that EER-1 may act by promoting DNA damage accumulation. Increased TRP53 phosphorylation and Cdkn1a mRNA levels indicated an activation of the TRP53/ATM DNA damage response pathway in response to EER-1, likely contributing to the induction of apoptosis and cell cycle arrest.

Conclusions

These results correlate VCP expression with malignancy in canine B cell lymphoma. The selective activity of EER-1 against lymphoma cells suggests that VCP will represent a clinically useful therapeutic target for the treatment of lymphoma. We further suggest a mechanism of EER-1 action centered on the DNA repair response that may be of central importance for the design and characterization of VCP inhibitory compounds for therapeutic use.

Electronic supplementary material

The online version of this article (doi:10.1186/s12885-015-1489-1) contains supplementary material, which is available to authorized users.

Expression of G protein-coupled estrogen receptor in irritable bowel syndrome and its clinical significance

OBJECTIVES

Estrogen is suggested to participate in pathogenesis of irritable bowel syndrome (IBS), but expression of G protein-coupled estrogen receptor (GPER) in the colon of IBS patients has never been investigated. The aim of this study was to investigate the expression of GPER and classical estrogen receptors in the colon of IBS patients and healthy controls.

METHODS

Colonic biopsies were obtained by endoscopy from patients with IBS (n=46) and healthy subjects (n=13). Expression of GPER, estrogen receptor α (ERα) and estrogen receptor β (ERβ) in mast cells were measured by double-labelling immunofluorescence. Quantification of mRNA expression was performed for GPER, ERα and ERβ by real-time polymerase chain reaction.

RESULTS

Differential distribution of GPER, ERα and ERβ were detected in human colonic mucosa. The expression of GPER in the cytoplasm of mast cells and GPER-positive cells was significantly higher in diarrhea-predominant IBS (D-IBS) patients than that in constipation-predominant IBS (C-IBS, P<0.001) patients and healthy subjects (P=0.005). ERα and ERβ were not detected in majority of mast cells in colonic mucosa and no difference of immunostaining results for ERα and ERβ was found among these three groups. A positive correlation (r=0.451, P=0.011) between GPER-positive cell counts and abdominal pain severity was observed in D-IBS group. Relative mRNA expression of GPER in D-IBS was also higher than that in C-IBS (P=0.018) and healthy subjects (P=0.011).

CONCLUSIONS

The present study, for the first time, demonstrated the expression of GPER in human colonic mucosa and its correlation with abdominal pain severity.