RNA-binding Motif Protein 3 Research Articles

Translational study reveals a two-faced role of RBM3 in pancreatic cancer and suggests its potential value as a biomarker for improved patient stratification.

Periampullary adenocarcinoma, including pancreatic cancer, is a heterogeneous group of tumors with dismal prognosis, partially due to lack of reliable targetable and predictive biomarkers. RNA-binding motif protein 3 (RBM3) has previously been shown to be an independent prognostic and predictive biomarker in several types of cancer. Herein, we examined the prognostic value of RBM3 in periampullary adenocarcinoma, as well as the effects following RBM3 suppression in pancreatic cancer cells in vitro. RBM3 mRNA levels were examined in 176 pancreatic cancer patients from The Cancer Genome Atlas. Immunohistochemical expression of RBM3 was analyzed in tissue microarrays with primary tumors and paired lymph node metastases from 175 consecutive patients with resected periampullary adenocarcinoma. Pancreatic cancer cells were transfected with anti-RBM3 siRNA in vitro and the influence on cell viability following chemotherapy, transwell migration and invasion was assessed. The results demonstrated that high mRNA-levels of RBM3 were significantly associated with a reduced overall survival (p = 0.026). RBM3 protein expression was significantly higher in lymph node metastases than in primary tumors (p = 0.005). High RBM3 protein expression was an independent predictive factor for the effect of adjuvant chemotherapy and an independent negative prognostic factor in untreated patients (p for interaction = 0.003). After siRNA suppression of RBM3 in vitro, pancreatic cancer cells displayed reduced migration and invasion compared to control, as well as a significantly increased resistance to chemotherapy. In conclusion, the strong indication of a positive response predictive effect of RBM3 expression in pancreatic cancer may be highly relevant in the clinical setting and merits further validation.

Involvement of TRPV3 and TRPM8 ion channel proteins in induction of mammalian cold-inducible proteins

Cold-inducible RNA-binding protein (CIRP), RNA-binding motif protein 3 (RBM3) and serine and arginine rich splicing factor 5 (SRSF5) are RNA-binding proteins that are transcriptionally upregulated in response to moderately low temperatures and a variety of cellular stresses in mammalian cells. Induction of these cold-inducible proteins (CIPs) is dependent on transient receptor potential (TRP) V4 channel protein, but seems independent of its ion channel activity. We herein report that in addition to TRPV4, TRPV3 and TRPM8 are necessary for the induction of CIPs. We established cell lines from the lung of TRPV4-knockout (KO) mouse, and observed induction of CIPs in them by western blot analysis. A TRPV4 antagonist RN1734 suppressed the induction in wild-type mouse cells, but not in TRPV4-KO cells. A TRPV3 channel blocker S408271 and a TRPM8 channel blocker AMTB as well as siRNAs against TRPV3 and TRPM8 suppressed the CIP induction in mouse TRPV4-KO cells and human U-2 OS cells. A TRPV3 channel agonist 2-APB induced CIP expression, but camphor did not. Neither did a TRPM8 channel agonist WS-12. These results suggest that TRPV4, TRPV3 and TRPM8 proteins, but not their ion channel activities are necessary for the induction of CIPs at 32 °C. Identification of proteins that differentially interact with these TRP channels at 37 °C and 32 °C would help elucidate the underlying mechanisms of CIP induction by hypothermia.

High RBM3 expression is associated with an improved survival and oxaliplatin response in patients with metastatic colorectal cancer.

BackgroundHigh expression of the RNA-binding motif protein 3 (RBM3) has been shown to correlate, with prolonged survival in several malignant diseases and with the benefit of platinum-based chemotherapy in ovarian cancer. The aim of this study was to evaluate RBM3 in metastatic colorectal cancer (mCRC) as a prognostic factor for overall survival and in relation to benefit of first-line chemotherapy.MethodsImmunohistochemical staining was conducted and evaluated in tumours from 455 mCRC patients. Kaplan-Meier analysis and Cox regression proportional hazards models were used to access the impact of RBM3 expression on overall survival (OS) and progression-free survival (PFS).ResultsHigh RBM3 expression, both nuclear and cytoplasmic, was an independent prognostic factor for prolonged OS (hazard ratio [HR] 0.67, 95% confidence interval [CI] 0.50–0.90 and HR 0.66, 95% CI 0.48–0.91, respectively). PFS was significantly longer in patients with high RBM3 expression who had received first-line oxaliplatin based treatment, compared to those who had received irinotecan based treatment, both regarding nuclear and cytoplasmic expression (p-value 0.020 and 0.022 respectively).ConclusionHigh RBM3 expression is an independent predictor of prolonged survival in mCRC patients, in particular in patients treated with first-line oxaliplatin based chemotherapy.

Hypothermia Prevents Retinal Damage Generated by Optic Nerve Trauma in the Rat

Ocular and periocular traumatisms may result in loss of vision. Hypothermia provides a beneficial intervention for brain and heart conditions and, here, we study whether hypothermia can prevent retinal damage caused by traumatic neuropathy. Intraorbital optic nerve crush (IONC) or sham manipulation was applied to male rats. Some animals were subjected to hypothermia (8 °C) for 3 h following surgery. Thirty days later, animals were subjected to electroretinography and behavioral tests. IONC treatment resulted in amplitude reduction of the b-wave and oscillatory potentials of the electroretinogram, whereas the hypothermic treatment significantly (p < 0.05) reversed this process. Using a descending method of limits in a two-choice visual task apparatus, we demonstrated that hypothermia significantly (p < 0.001) preserved visual acuity. Furthermore, IONC-treated rats had a lower (p < 0.0001) number of retinal ganglion cells and a higher (p < 0.0001) number of TUNEL-positive cells than sham-operated controls. These numbers were significantly (p < 0.0001) corrected by hypothermic treatment. There was a significant (p < 0.001) increase of RNA-binding motif protein 3 (RBM3) and of BCL2 (p < 0.01) mRNA expression in the eyes exposed to hypothermia. In conclusion, hypothermia constitutes an efficacious treatment for traumatic vision-impairing conditions, and the cold-shock protein pathway may be involved in mediating the beneficial effects shown in the retina.

TRPV4-dependent induction of a novel mammalian cold-inducible protein SRSF5 as well as CIRP and RBM3

Cold-inducible RNA-binding protein (CIRP) and RNA-binding motif protein 3 (RBM3) are two evolutionarily conserved RNA-binding proteins that are structurally related to hnRNPs and upregulated in response to moderately low temperatures in mammalian cells. Although contributions of splicing efficiency, the gene promoters activated upon mild hypothermia and the transcription factor Sp1 to induction of CIRP have been reported, precise mechanisms by which hypothermia and other stresses induce the expression of mammalian cold-inducible proteins (CIPs) are poorly understood. By screening the serine/arginine-rich splicing factors (SRSFs), we report that the transcript and protein levels of SRSF5 were increased in mammalian cells cultured at 32 °C. Expression of SRSF5 as well as CIRP and RBM3 were also induced by DNA damage, hypoxia, cycloheximide and hypotonicity. Immunohistochemical studies demonstrated that SRSF5 was constitutively expressed in male germ cells and the level was decreased in human testicular germ cell tumors. SRSF5 facilitated production of p19 H-RAS, and increased sensitivity to doxorubicin in human U-2 OS cells. Induction of CIPs was dependent on transient receptor potential vanilloid 4 (TRPV4) channel protein, but seemed independent of its ion channel activity. These findings indicate a previously unappreciated role for the TRP protein in linking environmental stress to splicing.

Expression of RNA-binding Motif Protein 3 (RBM3) and Cold-inducible RNA-binding protein (CIRP) Is Associated with Improved Clinical Outcome in Patients with Colon Cancer.

Recent studies have shown a potential role of RNA-binding proteins (RBPs) in a variety of biological pathways, including cancer progression, whilst their expression in various tumor types may be associated with patient prognosis. However, the role of the RBP family members has not been explored in colon cancer and their possible use as prognostic biomarkers is largely unknown. To determine the prognostic role of three RBP genes: insulin-like growth factor-binding protein 2 (IGFBP2), RNA-binding motif protein 3 (RBM3), and cold-inducible RNA-binding protein (CIRP) in colon cancer. We examined the RNA expression of IGFBP2, RBM3, and CIRP in 94 human colon cancer samples along with matched normal tissue samples from each patient using quantitative real-time polymerase chain reaction (qRT-PCR). No significant associations were observed between RNA expression of RBPs and the studied clinical features. The estimated 5-year disease-free survival rate was significantly better for patients with higher expression of RBM3 and CIRP, while patient survival was not significantly correlated to IGFBP2 expression. RBM3 and CIRP may be useful prognostic biomarkers of colon cancer.

Visualization of Protein-protein Interaction in Nuclear and Cytoplasmic Fractions by Co-immunoprecipitation and In Situ Proximity Ligation Assay.

Protein-protein interactions are involved in thousands of cellular processes and occur in distinct spatial context. Traditionally, co-immunoprecipitation is a popular technique to detect protein-protein interactions. Subsequent Western blot analysis is the most common method to visualize co-immunoprecipitated proteins. Recently, the proximity ligation assay has become a powerful tool to visualize protein-protein interactions in situ and provides the possibility to quantify protein-protein interactions by this method. Similar to conventional immunocytochemistry, the proximity ligation assay technique is also based on the accessibility of primary antibodies to the antigens, but in contrast, proximity ligation assay detects protein-protein interactions with a unique technique involving rolling-circle PCR, while conventional immunocytochemistry only shows co-localization of proteins. Nuclear factor 90 (NF90) and RNA-binding motif protein 3 (RBM3) have been previously demonstrated as interacting partners. They are predominantly localized in the nucleus, but also migrate into the cytoplasm and regulate signaling pathways in the cytoplasmic compartment. Here, we compared NF90-RBM3 interaction in both the nucleus and the cytoplasm by co-immunoprecipitation and proximity ligation assay. In addition, we discussed the advantages and limitations of these two techniques in visualizing protein-protein interactions in respect to spatial distribution and the properties of protein-protein interactions.

Stress Response Protein RBM3 Promotes the Development of Colitis-associated Cancer.

Colitis-associated cancer (CAC) is caused by chronic intestinal inflammation and often results from refractory inflammatory bowel disease (IBD). Stress response proteins Cirp and HSPA4 are involved in the refractory clinical course and development of CAC. RNA-binding motif protein 3 (RBM3) is induced in response to various stresses and is upregulated in several cancers. However, the role of RBM3 in CAC is unclear. We assessed RBM3 expression and function in 263 human intestinal mucosa samples from patients with IBD and in Rbm3-deficient (Rbm3) mice. Expression of RBM3 was correlated with the expression of stress response proteins Cirp, HSPA4, and HSP27 in the colonic mucosa of patients with IBD. Significant correlation was observed between the expression of RBM3 and that of Bcl-xL or stem cell markers. RBM3 expression increased and significantly correlated with R-spondin expression in the colonic mucosa of patients with refractory IBD, a condition associated with increased cancer risk, and RBM3 was overexpressed in human CACs. In the murine CAC model, Rbm3 deficiency decreased R-spondin and Bcl-xL expression and increased apoptotic cell number in the colonic mucosa, leading to reduced tumor multiplicity. Transplantation of wild-type and Rbm3 bone marrow did not alter tumor burden, indicating the importance of RBM3 in epithelial cells. Our findings indicated that RBM3 was required for efficient inflammatory carcinogenesis in the murine CAC model and suggested that RBM3 could be a predictive biomarker of CAC risk and a new therapeutic target for cancer prevention in patients with IBD.

Cold Shock Proteins Are Expressed in the Retina Following Exposure to Low Temperatures.

Hypothermia has been proposed as a therapeutic intervention for some retinal conditions, including ischemic insults. Cold exposure elevates expression of cold-shock proteins (CSP), including RNA-binding motif protein 3 (RBM3) and cold inducible RNA-binding protein (CIRP), but their presence in mammalian retina is so far unknown. Here we show the effects of hypothermia on the expression of these CSPs in retina-derived cell lines and in the retina of newborn and adult rats. Two cell lines of retinal origin, R28 and mRPE, were exposed to 32°C for different time periods and CSP expression was measured by qRT-PCR and Western blotting. Neonatal and adult Sprague-Dawley rats were exposed to a cold environment (8°C) and expression of CSPs in their retinas was studied by Western blotting, multiple inmunofluorescence, and confocal microscopy. RBM3 expression was upregulated by cold in both R28 and mRPE cells in a time-dependent fashion. On the other hand, CIRP was upregulated in R28 cells but not in mRPE. In vivo, expression of CSPs was negligible in the retina of newborn and adult rats kept at room temperature (24°C). Exposure to a cold environment elicited a strong expression of both proteins, especially in retinal pigment epithelium cells, photoreceptors, bipolar, amacrine and horizontal cells, Müller cells, and ganglion cells. In conclusion, CSP expression rapidly rises in the mammalian retina following exposure to hypothermia in a cell type-specific pattern. This observation may be at the basis of the molecular mechanism by which hypothermia exerts its therapeutic effects in the retina.

Cellular Functions of RNA-Binding Motif Protein 3 (RBM3): Clues in Hypothermia, Cancer Biology and Apoptosis.

Cell rapidly adapts to the harsh environment under certain conditions such as hypothermia and stress via activity of certain specific cold-shock proteins. Two cold shock proteins, RNA-binding motif protein 3 (RBM3) and coldinducible RNA binding proteins (CIRP), have been unveiled in human cells. RBM3, which is able to regulate their expression at the level of translation by binding to different transcripts, allows the cell to respond rapidly to environmental signals. Additionally, expression of RBM3 is induced under mild to moderate hypothermia, and stress. Stress-response pathways play an essential role in cancer. In different types of cancer, RBM3 is up regulated and correlated with favourable clinic- pathological features. RBM3 plays certain functions such as anti-apoptotic, cell proliferation enhancement, and a proto-oncogene function. Furthermore, Hypothermia-induced neuroprotection up- regulates RBM3 in neuronal cells. In this review, the multifunctional nature of RMB3 is outlined through summarizing the evidences from in vitro and in vivo studies.

Cold-inducible proteins CIRP and RBM3, a unique couple with activities far beyond the cold.

Cold-inducible RNA-binding protein (CIRP) and RNA-binding motif protein 3 (RBM3) are two evolutionarily conserved RNA-binding proteins that are transcriptionally upregulated in response to low temperature. Featuring an RNA-recognition motif (RRM) and an arginine–glycine-rich (RGG) domain, these proteins display many similarities and specific disparities in the regulation of numerous molecular and cellular events. The resistance to serum withdrawal, endoplasmic reticulum stress, or other harsh conditions conferred by RBM3 has led to its reputation as a survival gene. Once CIRP protein is released from cells, it appears to bolster inflammation, contributing to poor prognosis in septic patients. A variety of human tumor specimens have been analyzed for CIRP and RBM3 expression. Surprisingly, RBM3 expression was primarily found to be positively associated with the survival of chemotherapy-treated patients, while CIRP expression was inversely linked to patient survival. In this comprehensive review, we summarize the evolutionary conservation of CIRP and RBM3 across species as well as their molecular interactions, cellular functions, and roles in diverse physiological and pathological processes, including circadian rhythm, inflammation, neural plasticity, stem cell properties, and cancer development.

Effect of RNA binding motif protein 3 overexpression on Caspase 3 expression in swine testiclar cell under cold exposure

To investigate the change of apoptosis protein (Caspase 3) expression when RNA binding motif protein 3 (RBM3) overexpression in swine testicle (ST) cell line under cold stress (32℃) condition. In present study, RBM3 overexpression lentiviral vector (pLenti6/V5-GW/EmGFP-RBM3) and empty viral vector (pLenti6/V5-GW/EmGFP-DEST) with green fluorescent protein (GFP) that were successfully constructed in our laboratory were transfected into ST cells as overexpression virus group (OEV), empty vector virus (EVV) group and establishment of wildtype cell (WTC) group as the control group. The real-time fluorescence quantitative RCR (qPCR) and Western blot were used to detect expression of RBM3 mRNA and protein in each group, then cells in each group were cultured at 37℃ or 32℃ (2 h, 4 h, 8 h), the changes of Caspase 3 expression in each group were detected by enzyme linked immunosorbent assay (ELISA). Relative RBM3 gene and protein expression in OEV group were significantly higher than those in EVV group and WTC group. At the temperature of 37℃ and at 32℃ (2 h, 4 h, 8 h) in cold stress experiment, Caspase 3 expression in OEV group was significantly lower than those in EVV group and WTC group. RBM3 overexpression in ST cell line exposured to cold can significantly decreased the level of Caspase 3 expression, this study provides an experimental basis of RBM3 resistance against apoptosis of ST cells induced by low temperature.

RBM3 regulates temperature sensitive miR-142-5p and miR-143 (thermomiRs), which target immune genes and control fever.

Fever is commonly used to diagnose disease and is consistently associated with increased mortality in critically ill patients. However, the molecular controls of elevated body temperature are poorly understood. We discovered that the expression of RNA-binding motif protein 3 (RBM3), known to respond to cold stress and to modulate microRNA (miRNA) expression, was reduced in 30 patients with fever, and in THP-1-derived macrophages maintained at a fever-like temperature (40°C). Notably, RBM3 expression is reduced during fever whether or not infection is demonstrable. Reduced RBM3 expression resulted in increased expression of RBM3-targeted temperature-sensitive miRNAs, we termed thermomiRs. ThermomiRs such as miR-142–5p and miR-143 in turn target endogenous pyrogens including IL-6, IL6ST, TLR2, PGE2 and TNF to complete a negative feedback mechanism, which may be crucial to prevent pathological hyperthermia. Using normal PBMCs that were exogenously exposed to fever-like temperature (40°C), we further demonstrate the trend by which decreased levels of RBM3 were associated with increased levels of miR-142–5p and miR-143 and vice versa over a 24 h time course. Collectively, our results indicate the existence of a negative feedback loop that regulates fever via reduced RBM3 levels and increased expression of miR-142–5p and miR-143.

Cold-inducible RBM3 inhibits PERK phosphorylation through cooperation with NF90 to protect cells from endoplasmic reticulum stress.

The cold-inducible RNA-binding motif protein 3 (RBM3) is involved in the protection of neurons in hypoxic-ischemic and neurodegenerative disorders. RBM3 belongs to a small group of proteins whose synthesis increases during hypothermia while global protein production is slowed down. To investigate the molecular mechanisms underlying RBM3 action, we subjected hippocampal organotypic slice cultures from RBM3 knockout mice to various stressors and found exuberant signaling of the endoplasmic reticulum (ER) stress pathway PRKR-like ER kinase (PERK)-eukaryotic translation initiation factor 2α (eIF2α)-CCAAT/enhancer-binding protein homologous protein (CHOP) as compared with wild-type mice. Further, blocking RBM3 expression in human embryonic kidney HEK293 cells by specific small interfering RNAs increased phosphorylation of PERK and eIF2α, whereas overexpression of RBM3 prevented PERK-eIF2α-CHOP signaling during ER stress induced by thapsigargin or tunicamycin. RBM3 did not affect expression of the ER stress sensor immunoglobulin binding protein/GRP78. However, based on affinity purification coupled with mass spectrometry, coimmunoprecipitation, and proximity ligation assay, we revealed that nuclear factor 90 (NF90) is a novel protein interactor of PERK and that this interaction is essential for RBM3-mediated regulation of PERK activity, which requires an RNA-dependent interaction. In conclusion, our data provide evidence for a central role of RBM3 in preventing cell death by inhibiting the PERK-eIF2α-CHOP ER stress pathway through cooperation with NF90.

Loss of RNA‐binding motif protein 3 expression is associated with right‐sided localization and poor prognosis in colorectal cancer

RNA-binding motif protein 3 (RBM3) has recently been suggested as a prognostic biomarker in an array of human cancers. This study aimed to examine its effects in colorectal cancers. RBM3 expression was analysed by immunohistochemistry on a tissue microarray containing 1800 colorectal cancers (CRCs). Nuclear RBM3 immunohistochemical staining was found in 95.9% of all interpretable CRCs. Loss of RBM3 expression was linked to advanced tumour stage (P < 0.0001), right-sided tumour localization (P < 0.0001), and poor prognosis (P = 0.0003). In a multivariable analysis including RBM3 staining, tumour grade, tumour stage, and nodal status, only tumour stage and nodal status proved to be independent prognostic markers (P < 0.0001 each), whereas the prognostic impact of RBM3 staining was not significant (P = 0.2655). Our observations indicate that loss of RBM3 expression is an unfavourable prognostic marker in CRC, and is linked to right-sided tumour localization.

Cooling-Induced ER Stress is Good for Your Brain

Cooling-Induced ER Stress is Good for Your Brain

Preliminary Transcriptome Analysis in Lymphoblasts from Cluster Headache and Bipolar Disorder Patients Implicates Dysregulation of Circadian and Serotonergic Genes.

Bipolar disorder (BD) and cluster headache (CH) are distinct conditions with important similarities such as a temporal pattern of disturbances, dysregulation of the sleep-wake cycle, and response to lithium treatment in a proportion of patients. Aiming to identify common transcription signatures in these two disorders, we carried out an exploratory microarray gene expression analysis in lymphoblasts from 8 CH and 10 BD I patients selected for positive response to lithium and 10 healthy controls (CO). Gene expression levels of BD and CH were compared with CO to create two lists of differentially expressed genes. We then matched the two lists and focus on genes showing statistically significant difference and same change direction in both disorders. RNA binding motif protein 3 (RBM3) was the most significantly altered gene in the list (3.17 × 10(-13) in BD, 9.44 × 10(-14) in CH). Pathway analysis identified protein processing in endoplasmic reticulum as the most significantly enriched. For validation with quantitative reverse transcription PCR (qRT-PCR) using the same samples, we selected seven genes. Among these, we were able to validate the RBM3, nuclear receptor subfamily 1, group D, member 1 (NR1D1), and tryptophan hydroxylase 1 (TPH1). These genes encode for elements involved in circadian rhythm regulation (RBM3 and NR1D1) and in serotonin synthesis (TPH1), processes previously involved in both disorders, and in the mechanism of action of lithium.

Low RBM3 protein expression correlates with clinical stage, prognostic classification and increased risk of treatment failure in testicular non-seminomatous germ cell cancer.

BackgroundExpression of the RNA-binding motif protein 3 (RBM3) has been shown to correlate with favourable clinicopathological parameters and prognosis in several cancer diseases. The aim of this study was to examine the expression and prognostic ability of RBM3 in patients with testicular non-seminomatous germ cell tumours (NSGCT).Patients and MethodsImmunohistochemical RBM3 expression was analysed in tissue microarrays with tumours from 206 patients. Chi-square test was applied to analyze associations between RBM3 expression and clinicopathological parameters. Kaplan-Meier analysis was used to assess the impact of RBM3 expression on cancer-specific survival (CSS) and failure-free survival (FFS). Cox regression proportional hazards models were used to estimate the relative risk for failure.ResultsIn the entire cohort, there was a significant association between clinical stage (p=0.044) and RBM3 expression. Weak RBM3 expression correlated with a significantly reduced FFS [79.3% versus 90.4% (p=0.019)] and CSS [87.5% versus 97.3% (p=0.047)]. For patients with metastatic disease (n = 88), significant associations were found between RBM3 expression and IGCCC group (p=0.007). The FFS was significantly inferior for patients with low tumour-specific RBM3 expression [59.3% versus 79.0% (p=0.013)], and this association remained significant in a multivariable model for patients with metastatic disease (HR=3.67; 95% CI 1.14, 11.89).ConclusionLow RBM3 expression is an independent predictor of treatment failure in metastatic NSGCT, in relation to the prognostic factors included in the International Germ Cell Consensus Classification (IGCCC). These findings suggest that RBM3 may be a potential biomarker for treatment stratification in patients with metastatic non-seminomatous germ cell tumours, and therefore merit further validation.

Molecular characterization of RNA binding motif protein 3 (RBM3) gene from Pashmina goat

Pashmina goat inhabits the high altitude cold arid desert of Ladakh, India. This goat is known for its finest and costliest under fiber. Though the under fiber may be a part of its complex thermoregulation mechanism, the genetics of its adaptability under cold conditions is not known. As an attempt to understand its adaptive genetics, and the role of RNA-binding proteins at the cellular response, this study was conducted to characterize the RBM3 gene in Pashmina goat and its expression during hypothermia. The ORF of Pashmina RBM3 gene was 273 bp. Phylogenetic analysis revealed that Pashmina RBM3 is closely related to Bos taurus RBM3. Pashmina RBM3 was characterized by comparative modeling studies. The final 3-D model contained two α-helices and four β-sheets. qRT-PCR data showed that Pashmina RBM3 gene expression was significantly higher (P < 0.05) at moderate (30 °C) hypothermic stress conditions as compared with deep (15 °C) hypothermia.

Low Rbm3 Protein Expression Correlates with Clinical Stage, Prognostic Index and Increased Risk of Treatment Failure in Testicular Non-Seminomatous Germ Cell Cancer

ABSTRACT Aim: Expression of the RNA-binding motif protein 3 (RBM3) has in previous studies been shown to correlate with favourable clinicopathological parameters and prognosis in a number of cancer forms. The aim of this study was to examine the expression and prognostic ability of RBM3 in patients with non-seminomatous germ cell tumours (NSGCT). Methods: Immunohistochemical RBM3 expression was analysed in tissue microarrays with tumours from 206 patients with NSGCT. Chi-square test was applied to analyze associations between RBM3 expression and clinicopathological parameters. Kaplan-Meier analysis was used to assess the impact of RBM3 expression on cancer-specific survival (CSS) and progression-free survival (PFS). Cox regression proportional hazards models were used to estimate the relative risk for progression in both uni- and multivariable analysis. Results: In the entire cohort, there was a significant association between clinical stage (p=0.044) and RBM3 expression. Low RBM3 expression correlated with a significantly reduced PFS [67.7% versus 87.8% (p=0.001)] and CSS [87.5% versus 97.3% (p=0.047)]. For patients with metastatic disease (n=88), significant associations were found between RBM3 expression and IGCCC prognostic index (p=0.007), combined tumor marker status (p=0.001) and HCG level (p=0.010). The PFS was significantly inferior for patients with low tumour-specific RBM3 expression [40.0% versus 73.0% (p=0.002)], and this association remained significant in a multivariable model (HR=2.98; 95% CI 1.14, 7.75). Conclusions: Low RBM3 expression is significantly associated with a worse IGCCC-prognostic index and is an independent predictor of disease progression in metastatic NSGCT. These findings suggest that RBM3 may be a potential biomarker for treatment stratification in patients with metastatic non-seminomatous germ cell tumours, and therefore merit further validation. Disclosure: All authors have declared no conflicts of interest.