RRBP1 is highly expressed in prostate cancer and correlates with prognosis

Ribosome-binding protein-1 (RRBP1) expression in prostate carcinomas and its relationship with clinicopathological prognostic factors

INTRODUCTION

Studies in recent years have shown that ribosome-binding protein-1 (RRBP1) is expressed at high rates in many cancers and that it may be a potential prognostic biomarker. The objective of the present study is to determine the RRBP1 expression level in prostatic carcinoma and neighboring non-neoplastic prostate tissue, the relationship between its expression level with prognostic factors, and the role of RRBP1 in the development of prostate cancer.

MATERIALS AND METHODS

The study included 45 patients who were diagnosed with prostatic carcinoma and underwent radical prostatectomy in our center between the years 2010 and 2021. Pathology reports were reviewed. Mann-Whitney U test was used for the comparison of RRBP1 and GADPH values of the cases (control and tumoral tissue) between the primary tumor stage (pT) and Gleason score (GS) groups. Hierarchical regression analysis was used to explain the effective variables in explaining the RRBP1 value of the research cases.

RESULTS

According to the Mann-Whitney U test, mean and median RRBP1-T values of the cases with GS ≥ 8 were detected to be statistically significantly higher than the mean and median RRBP1-T values of the cases with GS < 8.

CONCLUSION

We found out that RRBP1 was expressed at higher rates in patients with high GS and advanced-stage patients. This result indicated that RRBP1 expression may be important in predicting the prognosis of prostate carcinoma.

RRBP1 depletion of bone metastatic cancer cells contributes to enhanced expression of the osteoblastic phenotype

Bone metastatic cancer-secreted extracellular factors are capable of modifying the bone microenvironment through interacting with bone cells, including osteoblasts. Reticulum ribosome-binding protein 1 (RRBP1) is substantially expressed in certain bone metastatic cancer cells. This study was undertaken to determine whether RRBP1 from bone metastatic cancer cells affects the osteoblastic phenotype expression. Breast and prostate cancer cells, MDA-MB-231 and PC3, were cultured, respectively, followed by collecting conditioned mediums (CMs) and identifying the abundance of RRBP1 in CMs using LC-MS/MS. MC3T3-E1 cells were cultured with a mixed medium (including CMs from shRRBP1-transduced two-type cancer cells) with or without endoplasmic reticulum (ER) stress inhibitor 4-PBA, followed by measuring the levels of osteoblastic phenotype expression and biomarkers of ER stress using western blotting, qPCR, and ARS staining, respectively. Similar experiments were performed in shRrbp1-transduced MC3T3-E1 cells cultured with a mixed medium (including CMs from the two-type cancer cells). Bone formation parameters were measured in the tibia of nude mice injected with shRRBP1-transduced two-type cancer cells using micro-CT analysis. These results showed that RRBP1 is the sole shared high-abundance protein in CMs from the two-type cancer cells, involving osteoblast differentiation. CMs from shRRBP1-transduced two-type cells boosted the osteoblastic phenotype expression partially through increasing ER stress. CMs from the two-type cancer cells partially offset the similar alterations induced by shRrbp1 in MC3T3-E1 cells. Injection with shRRBP1-transduced two-type cells ameliorated the bone lesions in nude mice. Therefore, RRBP1 depletion of bone metastatic cancer enhanced the osteoblastic phenotype expression, suggesting a role of RRBP1 in the bone microenvironment.

Endoplasmic reticulum stress increases exosome biogenesis and packaging relevant to sperm maturation in response to oxidative stress in obese mice

BACKGROUND

Mammalian sperm maturation in the epididymis is mainly modulated by exosomes that are secreted into the epididymal lumen from epididymal epithelial cells (EECs). Exposure to oxidative stress (OS) resulting from being fed a high fat diet (HFD) reduces sperm fertility, which is one of the cause inducing male infertility. Thus, we hypothesize that stress-induced changes in exosome content play a critical role in mediating this detrimental process.  METHODS: An obese mouse model was established by feeding a HFD. Then oxidative stress status was measured in the mouse caput epididymis, epididymal fluid and spermatozoa. Meanwhile, epididymis-derived purified exosomes were isolated and validated. Subsequently, liquid chromatography tandem mass spectrometry (LC-MS) was used to perform proteomic analysis of purified exosomes. Gene Ontology (GO) analysis was performed along with pathway enrichment to identify differentially expressed proteins (DEPs).

RESULTS

Two hundred and two DEPs mostly related to endoplasmic reticulum (ER) function were identified in the exosomes separated from the epididymis of control mice and obese mice. The ER stress and CD63 (an exosome marker), both increased in the caput epididymis of obese mice. Furthermore, an in vitro study showed that palmitic acid (PA), an-oxidative stress inducer, increased exosome biogenesis and secretion in the EECs.

CONCLUSION

Oxidative stress in the epididymal microenvironment induces ER stress in the EECs. This effect alters the epididymis-derived exosome content, profile and amounts of their differentially expressed ER proteins. Such changes may affect exosome biogenesis and cargo packaging, finally leading to abnormalities in sperm maturation and fertility.

Analysis of changes in the proteomic profile of porcine corpus luteum during different stages of the oestrous cycle: effects of PPAR gamma ligands

CONTEXT

The corpus luteum (CL) is an endocrine gland in the ovary of mature females during the oestrous cycle and pregnancy. There is evidence of a relationship between the secretory function of the CL and PPARs.

AIMS

In this study, we investigated the changes in the proteome of the CL in relation to the phase of the oestrous cycle and the impact of PPARγ ligands on the proteomic profile of the CL during the mid- and late-luteal phase of the oestrous cycle.

METHODS

The porcine CL explants were incubated in vitro for 6h in the presence of PPARγ ligands (agonist pioglitazone, antagonist T0070907) or without ligands. Global proteomic analysis was performed using the TMT-based LC-MS/MS method.

KEY RESULTS

The obtained results showed the disparity in proteomic profile of the untreated CL - different abundance of 23 and 28 proteins for the mid- and late-luteal phase, respectively. Moreover, seven proteins were differentially regulated in the CL tissue treated with PPARγ ligands. In the mid-luteal phase, one protein, CAND1, was downregulated after treatment with T0070907. In the late-luteal phase, the proteins SPTAN1, GOLGB1, TP53BP1, MATR3, RRBP1 and SRRT were upregulated by pioglitazone.

CONCLUSIONS

Comparative proteomic analysis revealed that certain proteins constitute a specific proteomic signature for each examined phase. Moreover, the study showed that the effect of PPARγ ligands on the CL proteome was rather limited.

IMPLICATIONS

The results provide a broader insight into the processes that may be responsible for the structural luteolysis of the porcine CL, in addition to apoptosis and autophagy.

Quantitative Proteomic Analysis of Cervical Cancer Tissues Identifies Proteins Associated With Cancer Progression

BACKGROUND/AIM

To date, several proteomics studies in cervical cancer (CC) have focused mainly on squamous cervical cancer (SCC). Our study aimed to discover and clarify differences in SCC and CAD that may provide valuable information for the identification of proteins involved in tumor progression, in CC as a whole, or specific for SCC or CAD.

MATERIALS AND METHODS

Total protein extracts from 15 individual samples corresponding to 5 different CC tissue types were compared with a non-cancerous control group using bidimensional liquid chromatography-mass spectrometry (2D LC-MS/MS), isobaric tags for relative and absolute quantitation (ITRAQ), principal component analysis (PCA) and gene set enrichment analysis (GSEA).

RESULTS

A total of 622 statistically significant different proteins were detected. Exocytosis-related proteins were the most over-represented, accounting for 25% of the identified and quantified proteins. Based on the experimental results, reticulocalbin 3 (RCN3) and Ras-related protein Rab-14 (RAB14) were chosen for further downstream in vitro and vivo analyses. RCN3 was overexpressed in all CC tissues compared to the control and RAB14 was overexpressed in squamous cervical cancer (SCC) compared to invasive cervical adenocarcinoma (CAD). In the tumor xenograft experiment, RAB14 protein expression was positively correlated with increased tumor size. In addition, RCN3-expressing HeLa cells induced a discrete size increment compared to control, at day 47 after inoculation.

CONCLUSION

RAB14 and RCN3 are suggested as potential biomarkers and therapeutic targets in the treatment of CC.

Role of Epigenetic Therapy in the Modulation of Tumor Growth and Migration in Human Castration-Resistant Prostate Cancer Cells with Neuroendocrine Differentiation

INTRODUCTION

Neuroendocrine transdifferentiation (NED) of prostate cancer (PC) cells is associated with the development of resistance to antiandrogen therapy and poor prognosis in patients with castration-resistant PC (CRPC). Many of the molecular events, involved in NED, appear to be mediated by epigenetic mechanisms. In this study, we evaluated the antitumor activity and epigenetic modulation of 2 epigenetic drugs, such as the demethylating agent 5-aza-2'-deoxycytidine (AZA) and the methyl donor S-adenosylmethionine (SAM), in 2 human CRPC cell lines with NED (DU-145 and PC-3).

METHODS

The effects of AZA and SAM on cell viability, cell cycle, apoptosis, migration, and genome-wide DNA methylation profiling have been evaluated.

RESULTS

Both drugs showed a prominent antitumor activity in DU-145 and PC-3 cells, through perturbation of cell cycle progression, induction of apoptosis, and inhibition of cell migration. AZA and SAM reversed NED in DU-145 and PC-3, respectively. Moreover, AZA treatment modified DNA methylation pattern in DU-145 cells, sustaining a pervasive hypomethylation of the genome, with a relevant effect on several pathways involved in the regulation of cell proliferation, apoptosis, and cell migration, in particular Wnt/β-catenin.

CONCLUSIONS

A relevant antitumor activity of these epigenetic drugs on CRPC cell lines with NED opens a new scenario in the therapy of this lethal variant of PC.

USP35 mitigates endoplasmic reticulum stress-induced apoptosis by stabilizing RRBP1 in non-small cell lung cancer

Deubiquitinating enzymes (DUBs) serve to maintain cellular homeostasis via protein ubiquitination and exert diverse regulatory functions in cancers and other diseases. Much progress has been made in characterizing biological roles of DUBs over the decades, yet the specific functions of many subclass members remain largely unexplored. It was not until recent years that the role of ubiquitin‐specific‐processing protease 35 (USP35) in cancers began to be understood. Here, we focus on delineating the roles and underlying mechanisms of USP35 in non‐small cell lung cancer (NSCLC). The isobaric tags for relative and absolute quantitation (iTRAQ) comparative proteomic approach were employed to identify differentially expressed proteins (DEPs) in H1299 cells induced by USP35 overexpression or silencing. Among the potential interactome of USP35, ribosome‐binding protein 1 (RRBP1), a membrane‐bound protein in endoplasmic reticulum (ER), captured our attentions. RRBP1 expression was found to positively correlate with USP35 levels in both genetically modified cells and human NSCLC tissues. Concordantly, both RRBP1 expression and USP35 expression were found to positively correlate with poor prognoses in lung adenocarcinoma patients. At the molecular level, USP35 was verified to directly interact with RRBP1 to prevent it from proteasomal‐dependent degradation. Functionally, USP35 alleviated ER stress‐induced cell apoptosis by stabilizing RRBP1 in NSCLC cells. Collectively, these findings indicate that USP35 plays a critical role in resisting ER stress‐induced cell death through deubiquitinating RRBP1, hence providing a rationale to target the USP35‐RRBP1 axis as an alternative therapeutic option for NSCLC.

βKlotho Inhibits Cell Proliferation by Downregulating ELK4 and Predicts Favorable Prognosis in Prostate Cancer

Objective

Prostate cancer (PCa) ranks as the second common malignancy in males worldwide. Although conspicuous progressions in diagnosis and treatment have been achieved in the past decades, the prognosis expectation of PCa remains unsatisfied yet. To improve the prognosis prediction of PCa, more specific biomarkers are needed. In this retrospective research, we focused on βKlotho and ETS-like transcription factor 4 (ELK4), aiming to identify potential prognostic biomarkers for PCa.

Methods

Western blotting was used to determine the expression of βKlotho, ELK4, and PARP in C4-2B and PC3 PCa cell lines. CCK-8 assay and colony formation assay were applied to examine the roles of βKlotho and ELK4 in the proliferation of PCa cells. The expression of βKlotho and ELK4 in PCa tissue samples was determined by immunochemistry. Pearson's χ2 test and Fisher's exact test were performed to investigate the associations among βKlotho, ELK4 and various clinical factors. Kaplan-Meier curves and Cox regression model were established to reveal the correlation among βKlotho, ELK4 expression and the prognosis of patients.

Results

βKlotho overexpression down-regulated the ELK4 expression, induced apoptosis and inhibited cell proliferation in both C4-2B and PC3 cells, which were reversed by ELK4 overexpression. βKlotho expression in PCa tissue samples had negative correlation with the ELK4 expression, and higher βKlotho expression was associated with lower Gleason score, absent distant metastasis and lower prostate-specific antigen (PSA) level. On the contrast, higher ELK4 expression was correlated with distant metastasis and higher PSA level. Moreover, βKlotho and ELK4 were both recognized as independent factors for the prognosis of patients with PCa.

Conclusion

βKlotho inhibits proliferation of prostate cancer cells by downregulating ELK4. Both βKlotho and ELK4 expressions correlate with the prognosis of PCa, which may serve as potential biomarkers for follow-up surveillance and prognostic assessments.

Hypomethylated RRBP1 Potentiates Tumor Malignancy and Chemoresistance in Upper Tract Urothelial Carcinoma

Ribosome-binding protein 1 (RRBP1) is a potential oncogene in several cancer types. However, the correlation between RRBP1 expression and the prognosis of patients with upper tract urothelial carcinoma (UTUC) remains unclear. In this study, we identified that RRBP1 is associated with carcinogenesis and metastasis in UTUC using a methylation profiling microarray. High correlations between RRBP1 and cancer stages, nodal metastasis status, molecular subtypes, and prognosis in bladder urothelial cancer (BLCA) were found. Aberrant DNA methylation in the gene body region of RRBP1 was determined in UTUC tissues by methylation-specific PCR. RRBP1 expression was significantly increased in UTUC tissues and cell lines, as determined by real-time PCR and immunohistochemistry. RRBP1 depletion significantly reduced BFTC909 cell growth induced by specific shRNA. On the other hand, molecular subtype analysis showed that the expression of RRBP1 was associated with genes related to cell proliferation, epithelial-mesenchymal transition, and basal markers. A patient-derived organoid model was established to analyze patients' responses to different drugs. The expression of RRBP1 was related to chemoresistance. Taken together, these results provide the first evidence that RRBP1 gene body hypomethylation predicts RRBP1 high expression in UTUC. The data highlight the importance of RRBP1 in UTUC malignancy and chemotherapeutic tolerance.

RRBP1 rewires cisplatin resistance in oral squamous cell carcinoma by regulating Hippo pathway

BACKGROUND

Chemoresistance is one of the major factors for treatment failure in OSCC. Identifying key resistance triggering molecules will be useful strategy for developing novel treatment methods.

METHODS

To identify the causative factors of chemoresistance, we performed RNA sequencing and global proteomic profiling of human OSCC lines presenting with sensitive, early and late cisplatin-resistance patterns.

RESULTS

From the common set of dysregulated genes from both the analysis, RRBP1 was identified to be upregulated in both early and late cisplatin-resistant cells with respect to the sensitive counterpart. Analysis of OSCC patient sample indicates that RRBP1 expression is upregulated in chemotherapy-non-responder tumours as compared to chemotherapy-responder tumours. Genetic (knockout) or pharmacological (Radezolid, represses expression of RRBP1) inhibition of RRBP1 restores cisplatin-mediated cell death in chemo-resistant OSCC. Mechanistically, RRBP1 regulates Yes-associated protein1 (YAP1), a key protein in the Hippo pathway to induce chemoresistance. The PDC xenograft data suggests that knockout of RRBP1 induces cisplatin-mediated cell death and facilitates a significant reduction of tumour burden.

CONCLUSION

Overall, our data suggests that (I) RRBP1 is a major driver of cisplatin-resistance in OSCC, (II) RRBP1 regulates YAP1 expression to mediate cisplatin-resistance, (III) Radezolid represses RRBP1 expression and (IV) targeting RRBP1 reverses cisplatin-induced chemoresistance in advanced OSCC.

RRBP1 is highly expressed in bladder cancer and is associated with migration and invasion

Ribosome-binding protein 1 (RRBP1) is a marker for colorectal, lung, esophageal and prostate cancer. However, the association between RRBP1 and bladder cancer is not completely understood. The present study aimed to evaluate the expression and function of RRBP1 in bladder cancer. The association between RRBP1 expression and clinicopathological characteristics, as well as the prognosis of bladder cancer was analyzed. RRBP1 expression was further analyzed in bladder cancer cell lines via reverse transcription-quantitative PCR and western blotting. RRBP1 knockdown was established using short hairpin RNAs to investigate the function of RRBP1 in T24 cells. Compared with healthy bladder tissue, RRBP1 expression levels were significantly upregulated in bladder cancer tissue. High RRBP1 expression was associated with tumor stage, lymph node metastasis and shorter overall survival time. RRBP1 protein was highly expressed in bladder cancer cell lines compared with normal SV-HUC-1 cells. Compared with the control group, RRBP1 knockdown inhibited T24 migration and invasion by downregulating the expression of C-C chemokine receptor type 7 (CCR7) protein. In conclusion, the present study indicated that RRBP1 was associated with bladder cancer migration, invasion and prognosis, and CCR7 might serve a role in the process.

Ribosome Binding Protein 1 Correlates with Prognosis and Cell Proliferation in Bladder Cancer

Introduction

Ribosome binding protein 1 (RRBP1) is reported to be correlated with tumor formation and progression. However, the role of RRBP1 in bladder cancer is unclear. In this study, we aimed to investigate the expression of RRBP1 and its influence on cell proliferation in bladder cancer.

Methods

Quantification real-time polymerase chain reaction (qRT-PCR) and immunohistochemistry (IHC) were used to detect the expression levels of RRBP1 in 138 bladder cancer and matched adjacent normal bladder tissues. Then, the clinical significance of RRBP1 in bladder cancer was evaluated. The effect of RRBP1 on cell proliferation and its potential mechanism were further explored.

Results

Results show that the mRNA levels of RRBP1 in bladder cancer were significantly higher compared with those in normal tissues (P< 0.001). IHC results show the high-expression rate of RRBP1 in bladder cancer was 68.8%, which was significantly greater than those in normal tissues (40.6%, P< 0.001). RRBP1 high-expression was significantly associated with differentiation, T stage and lymph node metastasis in bladder cancer (P< 0.05). The overall survival time of patients with RRBP1 high-expression was significantly reduced compared to those with RRBP1 low-expression. Moreover, RRBP1 overexpression significantly promoted cell proliferation, which was correlated with Smad1/Smad3/TGF-β1 signal pathway.

Conclusion

RRBP1 high-expression correlates with prognosis and promotes cell proliferation in bladder cancer, which could be a potential biomarker.

Correlation between reticulum ribosome-binding protein 1 (RRBP1) overexpression and prognosis in cervical squamous cell carcinoma

Our purpose was to evaluate the correlation between endoplasmic reticulum ribosomal binding protein 1 (RRBP1) expression in cervical squamous cell carcinoma (CSCC) and poor patient prognosis. RRBP1 is a nascent transporter that is situated on the rough endoplasmic reticulum (ER). It adjusts to the secretion of proteins in cells and alleviates ER stress, thus stimulating cell proliferation. An immunohistochemical (IHC) study was conducted to detect the expression level of RRBP1 on 96 CSCC tissue samples. Western blot and Quantitative real-time polymerase chain reaction (qRT-PCR) were performed to compare the expression levels of RRBP1 in cervical squamous cell carcinoma with healthy cervical tissues. An overexpression of RRBP1 was observed in CSCC tissues, and the expression level was associated with FIGO stage (Stage I vs. II: 52.6% vs. 74.1%, p = 0.030), and lymph node metastasis (No vs. Yes: 61.5% vs. 92.3%, p = 0.031) but not patient age and tissue differentiation. Univariate survival analysis indicated that prognosis was associated with the expression level of RRBP1 and tissue differentiation and lymph node metastasis. Analysis of the multi-factor survival Cox model proved that RRBP1 was an independent prognostic factor. In conclusion, compared with healthy cervical tissues, RRBP1 was overexpressed in CSCC tissues, illustrating that RRBP1 may be a new biomarker for the diagnosis of CSCC. The study on RRBP1 may contribute to exploring the pathogenesis of CSCC and may also guide targeted therapy for CSCC in the future.

High glucose may promote the proliferation and metastasis of hepatocellular carcinoma via E2F1/RRBP1 pathway

AIMS

Diabetes is considered as one of the important risks in the progression of Hepatocellular carcinoma(HCC). Ribosome binding protein 1 (RRBP1), a rough endoplasmic reticulum protein, plays an essential role in diabetes and various cancer. E2F transcription factor 1 (E2F1), an upstream transcription factor of RRBP1, shows promoting tumor progression effect in multifarious cancers. In this research, we tried to identify whether regulating E2F1/RRBP1 pathway could inhibit the proliferation and metastasis of HepG2 cells induced by high glucose.

MAIN METHODS

Proteomic, bioinformatics, molecular biology including RT-qPCR and Western blot, cell biology containing Cell Counting Kit-8 (CCK-8), wound healing assay and transwell assay, and biochemistry analyses incorporating Luciferase assay and CHIP assay were used in this study.

KEY FINDINGS

High glucose promoted the proliferation and metastasis of HepG2 cells through up-regulating the expression of RRBP1. Bioinformatics analysis predicted that E2F1 might be the transcription factor of RRBP1. Knocking-down of E2F1 down-regulated mRNA and protein expression levels of RRBP1 in HepG2 cells significantly and suppressed the proliferation, migration and invasion of cells remarkably, Reverse effect was observed in cells that E2F1 was overexpressed. Meanwhile, luciferase and CHIP assay determined that E2F1 could bind to the RRBP1 promoter and promote the transcription of RRBP1. Finally, rescue assay verified the important role of RRBP1/E2F1 axis in the process of HepG2 cells proliferation and metastasis.

SIGNIFICANCE

All of the above provided possibility to improve the efficiency of HCC complicated with diabetes treatment by regulating the E2F1/RRBP1 pathway.

Increased expression of CD81 is associated with poor prognosis of prostate cancer and increases the progression of prostate cancer cells in vitro

CD81, a member of the tetraspanin family, has been revealed to be upregulated and associated with prognosis in several types of cancer; however, this relationship has not been explored in prostate cancer. The present study aimed to investigate the prognostic significance and functional role of CD81 in prostate cancer. The expression of CD81 in prostate cancer tissues and cell lines was evaluated using qRT-PCR analysis. Kaplan-Meier survival analysis and Cox regression analysis were conducted to explore the prognostic significance of CD81. Cell experiments were used to explore the effects of CD81 on cell proliferation, migration, and invasion in prostate cell lines in vitro. The expression of CD81 was increased in both prostate cancer tissues and cell lines. Upregulation of CD81 was significantly associated with lymph node metastasis and TNM stage. Moreover, patients with high CD81 levels had poorer overall survival than those with lower levels. Additionally, tumor cell proliferation, migration, and invasion were inhibited by knockdown of CD81. The present results indicated that CD81 plays an oncogenic role in prostate cancer. Overexpression of CD81 may serve as a prognostic biomarker and therapeutic target and is involved in the progression of prostate cancer.