Y box binding protein 1 inhibition as a targeted therapy for ovarian cancer.

Y box binding protein 1 (YB-1) is a multifunctional protein associated with tumor progression and the emergence of treatment resistance (TR). Here, we report an azopodophyllotoxin small molecule, SU056, that potently inhibits tumor growth and progression via YB-1 inhibition. This YB-1 inhibitor inhibits cell proliferation, resistance to apoptosis in ovarian cancer (OC) cells, and arrests in the G1 phase. Inhibitor treatment leads to enrichment of proteins associated with apoptosis and RNA degradation pathways while downregulating spliceosome pathway. In vivo, SU056 independently restrains OC progression and exerts a synergistic effect with paclitaxel to further reduce disease progression with no observable liver toxicity. Moreover, in vitro mechanistic studies showed delayed disease progression via inhibition of drug efflux and multidrug resistance 1, and significantly lower neurotoxicity as compared with etoposide. These data suggest that YB-1 inhibition may be an effective strategy to reduce OC progression, antagonize TR, and decrease patient mortality.

Novel Serine 176 Phosphorylation of YBX1 Activates NF-κB in Colon Cancer.

Y box protein 1 (YBX1) is a well known oncoprotein that has tumor-promoting functions. YBX1 is widely considered to be an attractive therapeutic target in cancer. To develop novel therapeutics to target YBX1, it is of great importance to understand how YBX1 is finely regulated in cancer. Previously, we have shown that YBX1 could function as a tumor promoter through phosphorylation of its Ser-165 residue, leading to the activation of the NF-κB signaling pathway (1). In this study, using mass spectrometry analysis, we discovered a distinct phosphorylation site, Ser-176, on YBX1. Overexpression of the YBX1-S176A (serine-to-alanine) mutant in either HEK293 cells or colon cancer HT29 cells showed dramatically reduced NF-κB-activating ability compared with that of WT-YBX1, confirming that Ser-176 phosphorylation is critical for the activation of NF-κB by YBX1. Importantly, the mutant of Ser-176 and the previously reported Ser-165 sites regulate distinct groups of NF-κB target genes, suggesting the unique and irreplaceable function of each of these two phosphorylated serine residues. Our important findings could provide a novel cancer therapy strategy by blocking either Ser-176 or Ser-165 phosphorylation or both of YBX1 in colon cancer.

Cyclin A correlates with YB1, progression and resistance to chemotherapy in human epithelial ovarian cancer.

BACKGROUND: Cyclin A is a cell-cycle regulatory gene and its overexpression promotes tumor cell growth. Y-Box-binding protein 1 (YB1) is a transcription/translation factor involved in tumor growth, invasion, and drug resistance. We investigated whether an association exists between protein products of these genes in epithelial ovarian cancer (EOC) specimens and clinicopathological parameters, patient response and EOC sensitivity to platinum-based first-line chemotherapy. PATIENTS AND METHODS: Cyclin A and YB1 expression were analyzed by immunohistochemistry in 54 human primary EOC tissues. Immunolabeling of both proteins was graded according to their staining intensity (scale 0-3) and the proportion of immunostained cancer cells (scale 0-4) to obtain a staining index (SI; value=0-12). RESULTS: Significantly higher cyclin A immunostaining (SI≥4) in EOC specimens was discovered in patients with advanced (International Federation of Gynaecology and Obstetrics (FIGO) III and IV, p=0.003), poorly differentiated (G3, p<0.001) tumors, and tumors of those with residual disease>1 cm (p=0.001). YB1 immunostaining was significantly higher in EOCs from patients with suboptimal debulking (p=0.025). Over-expression of cyclin A (SI≥9) in EOCs was significantly linked with poorer patient response (p=0.001) and higher resistance of tumors to platinum-based first-line chemotherapy (p=0.007), while immunolabeling of YB1 in EOCs was not significantly associated with either of these variables (p>0.05). Cyclin A expression was significantly and positively correlated with that of YB1 (R=0.588, p<0.001). CONCLUSION: Increased cyclin A expression in EOC is related to a more aggressive tumor behavior and predicts the response of patients to first-line platinum-based chemotherapy.

Identification of cervical cancer markers using cDNA subtraction approach.

PURPOSE OF INVESTIGATION: Cervical cancer markers are not well known for accurate detection of the disease. MATERIALS AND METHODS: In the present study, cervical cancer samples were collected from the 42 patients in the Department of Surgery and Medicine of Weifang People's Hospital and Medical College, Shandong, China. The cDNA subtraction approach was performed to find out the specific transcripts, which are responsible for cervical cancer. The specific differentially expressed transcripts were identified by Basic Local Alignment Search Tool (BLAST) analysis and the results were validated by immunohistochemistry. RESULTS: Following differentially expressed specific transcripts, such as ID-1, Hif 1a, and the Y-box were usefully employed as a marker to accurately detect cervical cancer. CONCLUSION. The identified markers are promising in the accurate detection of cervical cancer in terms of its molecular basis and management of the disease.

Identification of proteomic biomarkers predicting prostate cancer aggressiveness and lethality despite biopsy-sampling error.

BACKGROUND: Key challenges of biopsy-based determination of prostate cancer aggressiveness include tumour heterogeneity, biopsy-sampling error, and variations in biopsy interpretation. The resulting uncertainty in risk assessment leads to significant overtreatment, with associated costs and morbidity. We developed a performance-based strategy to identify protein biomarkers predictive of prostate cancer aggressiveness and lethality regardless of biopsy-sampling variation. METHODS: Prostatectomy samples from a large patient cohort with long follow-up were blindly assessed by expert pathologists who identified the tissue regions with the highest and lowest Gleason grade from each patient. To simulate biopsy-sampling error, a core from a high- and a low-Gleason area from each patient sample was used to generate a 'high' and a 'low' tumour microarray, respectively. RESULTS: Using a quantitative proteomics approach, we identified from 160 candidates 12 biomarkers that predicted prostate cancer aggressiveness (surgical Gleason and TNM stage) and lethal outcome robustly in both high- and low-Gleason areas. Conversely, a previously reported lethal outcome-predictive marker signature for prostatectomy tissue was unable to perform under circumstances of maximal sampling error. CONCLUSIONS: Our results have important implications for cancer biomarker discovery in general and development of a sampling error-resistant clinical biopsy test for prediction of prostate cancer aggressiveness.

Peroxiredoxins, thioredoxin, and Y-box-binding protein-1 are involved in the pathogenesis and progression of dialysis-associated renal cell carcinoma.

Patients with end-stage renal disease are exposed to increased oxidative stress and impairment of antioxidant mechanisms. We focused on dialysis renal cell carcinoma (RCC), including epithelial hyperplasia in acquired cystic disease of the kidney (ACDK). We attempted to obtain insight into the carcinogenesis and tumor progression in terms of cellular defense mechanisms associated with oxidative stress by investigating the expression of antioxidant proteins by immunohistochemistry. We evaluated retrospectively 43 cases of dialysis RCC and, as a control group, 49 cases of sporadic RCC. Peroxiredoxin (Prx) 1, 3, 4, 5, and 6 expression in dialysis RCC was positively correlated with the duration of dialysis. In epithelial hyperplasia, in 17 cases of acquired cystic disease of the kidney, Prxs and thioredoxin were highly expressed. Moreover, in dialysis RCC, Prx 3, 4, and 5 immunoreactivity and nuclear expression of Y-box-binding protein-1 were higher than in sporadic RCC. In dialysis RCC, Prx 3, 4, and 5 immunoreactivity positively correlated with the Fuhrman nuclear grade. These data suggest that oxidative stress during dialysis enhances antioxidant activity, with an inhibiting effect on carcinogenesis. Once cancer has developed, antioxidant activity might have a stimulating effect on the progression of dialysis RCC.

Low expression of the X-linked ribosomal protein S4 in human serous epithelial ovarian cancer is associated with a poor prognosis.

BACKGROUND: The X-linked ribosomal protein S4 (RPS4X), which is involved in cellular translation and proliferation, has previously been identified as a partner of the overexpressed multifunctional protein YB-1 in several breast cancer cells. Depletion of RPS4X results in consistent resistance to cisplatin in such cell lines. METHODS: As platinum-based chemotherapy is a standard first line therapy used to treat patients with ovarian cancer, we evaluated the prognostic value of RPS4X and YB-1 at the protein level in specimen from 192 high-grade serous epithelial ovarian cancer patients. RESULTS: Immunohistochemistry studies indicated that high expression of RPS4X was associated with a lower risk of death and later disease progression (HR = 0.713, P = 0.001 and HR = 0.761, P = 0.001, respectively) as compared to low expression of RPS4X. In contrast, YB-1 was not significantly associated with either recurrence or survival time in this cohort. Finally, the depletion of RPS4X with different siRNAs in two different ovarian cancer cell lines reduced their proliferative growth rate but more importantly increased their resistance to cisplatin. CONCLUSION: Altogether, these results suggest that the levels of RPS4X could be a good indicator for resistance to platinum-based therapy and a prognostic marker for ovarian cancer. Our study also showed that RPS4X is an independent prognostic factor in patients with serous epithelial ovarian cancer.

Strong YB-1 expression is associated with liver metastasis progression and predicts shorter disease-free survival in advanced gastric cancer.

BACKGROUND: The most significant cause of gastric cancer (GC) death is metastasis, although the underlying mechanisms remain obscure. Y-box binding protein-1 (YB-1) is associated with tumor aggressiveness and poor prognosis in various cancers. In this study we investigated the relationship between YB-1 expression and the clinicopathologic features and metastasis-associated epithelial-mesenchymal transition (EMT) phenotype in advanced GC patients. PATIENTS AND METHODS: Immunohistochemistry (IHC) was used to analyze YB-1, E-cadherin, and vimentin expression in 98 advanced GC cases. RESULTS: Twenty-nine (29.6%) cases of GC exhibited strong YB-1 immunoreactivity. Strong YB-1 staining occurred more often in patients with intestinal or non-scirrhous cancer, and demonstrated a significant correlation with vascular invasion (VI), liver metastasis, and shorter disease-free survival (DFS). However, we observed no relationship between YB-1 expression and EMT phenotype or overall survival. Logistic regression analysis revealed that strong staining for YB-1 was the only predictive factor for liver metastasis. CONCLUSIONS: Our results indicate that YB-1 plays a role in the process of GC metastasis, and that the immunohistochemical detection of this protein potentially delivers valuable insight regarding the prediction of liver metastasis and shorter DFS in patients undergoing curative resection for advanced GC.

Overexpression of Y-box binding protein-1 in cervical cancer and its association with the pathological response rate to chemoradiotherapy.

The aim of this study was to evaluate the expression of Y-box binding protein-1 (YB-1) in nonneoplastic cervical tissue and cervical cancer tissue and to evaluate its relationship with chemoradiosensitivity in the cases of cervical cancer. We performed immunohistochemical studies to examine YB-1 expression among 59 patients with cervical cancer, 30 with cervical intraepithelial neoplasia (CIN), and 30 with cervicitis. The mean YB-1 histological score(HSCORE)values for cervicitis, cervical CIN, and cervical cancer tissues were 22.3, 39, and 84.4, respectively. The mean YB-1 HSCORE value was 80.0 for cervical cancer patients who showed complete pathological response to chemoradiotherapy and 144.3 for cervical cancer patients who showed partial pathological response. Our data showed that the YB-1 expression was the highest in cervical cancer tissue, followed by cervical CIN tissue, and then cervicitis tissues. High YB-1 expression resulted in a lower pathological response rate in patients of cervical cancer than low YB-1 expression did. Our results implied that YB-1 may play a role in the genesis of cervical cancer and that high YB-1 expression decreases the chemoradiosensitivity of cervical cancers.

Nuclear expression of YB-1 in diffuse large B-cell lymphoma: correlation with disease activity and patient outcome.

The aim of this study is to investigate the correlations among Y-box binding protein-1 (YB-1) and P-glycoprotein(P-gp) and their prognostic significance in diffuse large B-cell lymphoma (DLBCL). The expression of YB-1 and P-gp was examined immunohistochemically on 68 patients with DLBCL who were treated from 2003 to 2005. Samples were paraffin-embedded newly diagnosed DLBCL tissues taken from the surgical specimens before adjuvant chemotherapy. We determined the prognostic significance of YB-1 and its relationship with P-gp in patients with DLBCL. Of the 68 tumors examined, 42 (61.8%) were positive for YB-1 expression in the nucleus. The nuclear expression of YB-1 was significantly associated with clinical stages, bone marrow involvement, extra nodal involvement, and poor response to chemotherapy. No associations were observed between P-gp and clinical features, in context of the poor response to chemotherapy. Nuclear expression of YB-1 was correlated significantly with increased expression of P-gp patients with a nuclear YB-1 tumor had a poorer prognosis than did those with a cytoplasmic YB-1 tumor in all of the DLBCL patients (P = 0.035). Thus, correlation of YB-1 and P-gp emerged as a possible biomarker for unfavorable prognosis in DLBCL. It may provide useful information for clinicians to determine the appropriate therapy for each type of DLBCL.

Different expression profiles of Y-box-binding protein-1 and multidrug resistance-associated proteins between alveolar and embryonal rhabdomyosarcoma.

Nuclear expression of the Y-box-binding protein-1 (YB-1) has been reported to regulate the expression of both P-glycoprotein (P-gp) and major vault protein (MVP), and to regulate proliferative activities in human malignancies. Based on morphology and molecular biology, rhabdomyosarcoma (RMS) can be divided into two major types: embryonal type and the more aggressive alveolar type. Thirty-five cases of embryonal RMS (ERMS) and 28 cases of alveolar RMS (ARMS) were examined immunohistochemically for the nuclear expression of YB-1 and the intrinsic expression of P-gp, multidrug resistance (MDR)-associated protein (MRP) 1, 2, and 3, breast-cancer resistant protein (BCRP) and MVP, and the findings were compared with proliferative activities as evaluated by the MIB-1-labeling index (LI). Moreover, mRNA levels of these MDR-related molecules were assessed using a quantitative reverse transcriptase-PCR method in 18 concordant frozen materials. P-gp expression was more frequently observed ARMS, compared with ERMS (P = 0.0332), whereas immunoreactivity for BCRP was more frequently recognized in ERMS (P = 0.0184). Nuclear expression of YB-1 protein was correlated with P-gp (P = 0.0359) and MVP (P = 0.0044) expression, and a higher MIB-1-labeling index (P = 0.0244) in ERMS, however, in ARMS no such relationships were observed. These immunohistochemical results indicate that different expression profiles of MDR-related molecules and their correlation with YB-1 nuclear expression support the concept that ERMS and ARMS are molecular biologically distinct neoplasms. Apart from ERMS, frequent P-gp expression in ARMS may be independent from YB-1 regulation. However, YB-1 may be a candidate for a molecular target in rhabdomyosarcoma therapy, especially in ERMS.

[YB-1 protein expression in ovarian cancer]. / Ekspresja bialka YB-1 w nowotworach jajnika.

OBJECTIVES: Unfavourable prognosis of ovarian cancer is due to prompt progression, advanced stage at time of diagnosis and chemoresistance. No protein tissue prognosticators of ovarian cancer are in clinical use yet. YB-1 belongs to a family of "cold shock proteins" and participates at gene expression control at several levels. High expression of YB-1 in tumour tissue correlates with unfavourable prognosis and chemoresistance in some malignant neoplasms. THE AIM: of this study was to determine the expression of YB-1 in benign and malignant ovarian neoplasms and to correlate the expression of YB-1 with clinical indicators of cancer progression. METHODS: Specimens of 11 benign ovarian cysts and 14 cystadenocarcinomas of the ovary were obtained.YB-1 expression was determined by immunohistochemistry. Staging of ovarian cancer was performed according to FIGO. RESULTS: Mean YB-1 expression levels in benign and malignant tumours were 5.36 +/- 4.1 and 2.86 +/- 4.18 points respectively and were not significantly different (p=0.18). No correlation between FIGO stage and expression of YB-1 was found in the group of ovarian cancers, either (p=0.32). CONCLUSIONS: This study demonstrates that YB-1 is expressed both in benign and malignant ovarian tumors. Although there we didn't found any correlation between YB-1 expression and FIGO stage, YB-1 could be useful in the prognosis recurrence after chemotherapy.

Increased nuclear localization of transcription factor Y-box binding protein 1 accompanied by up-regulation of P-glycoprotein in breast cancer pretreated with paclitaxel.

PURPOSE: The Y-box binding protein 1 (YB-1) regulates expression of P-glycoprotein encoded by the MDR1 gene. There have been no previous studies regarding the involvement of YB-1 in the development of resistance to paclitaxel. The present study was done to examine how paclitaxel affects the localization and expression of YB-1 in breast cancer. EXPERIMENTAL DESIGN: We evaluated the expression and localization of YB-1 and P-glycoprotein in breast cancer tissues obtained from 27 patients before and after treatment with paclitaxel. The effect of paclitaxel on localization of cellular YB-1 was examined by using GFP-YB-1. Interaction of YB-1 with the Y-box motif of the MDR1 promoters was studied by electrophoretic mobility shift assay. The effects of paclitaxel on MDR1 promoter activity were examined by luciferase assay. RESULTS: Of 27 breast cancer tissues treated with paclitaxel, nine (33%) showed translocation of YB-1 from the cytoplasm to the nucleus together with increased expression of P-glycoprotein during the course of treatment. Twelve breast cancer tissues (44%) showed neither translocation of YB-1 nor increased expression of P-glycoprotein. Nuclear translocation of YB-1 was correlated significantly with increased expression of P-glycoprotein (P=0.0037). Confocal analysis indicated that paclitaxel induced nuclear translocation of green fluorescent fused YB-1 in MCF7 cells. Furthermore, binding of YB-1 to the Y-box of MDR1 promoter was increased in response to treatment with paclitaxel. In addition, MDR1 promoter activity was significantly up-regulated by paclitaxel in MCF7 cells (P<0.001). CONCLUSIONS: The results of the present study suggested that YB-1 may be involved in the development of resistance to paclitaxel in breast cancer.

The up-regulation of Y-box binding proteins (DNA binding protein A and Y-box binding protein-1) as prognostic markers of hepatocellular carcinoma.

PURPOSE: The development of hepatocellular carcinoma is associated with the chronic inflammation of the liver caused by various factors such as hepatitis B or C virus infection. Previously, we reported DNA binding protein A (dbpA) as a candidate molecule that can accelerate inflammation-induced hepatocarcinogenesis. DbpA belongs to the Y-box binding protein family, and Y-box binding protein-1 (YB-1), the prototype member of this family, is reported to be a prognostic marker of malignant diseases other than hepatocellular carcinoma. The purpose of this study is to examine the significance of the expression of dbpA or of the T-to-G transversion in the dbpA promoter region, which enhances the promoter activity in vitro, for the progression of hepatocellular carcinoma. EXPERIMENTAL DESIGN: We studied the expression of dbpA (as well as of YB-1) in 82 formalin-fixed hepatocellular carcinoma tissues by immunohistochemistry and determined the sequence of the dbpA promoter region in 42 frozen hepatocellular carcinoma tissues. We examined the relationship between these findings and the clinicopathologic factors of hepatocellular carcinoma patients. RESULTS: DbpA expression was associated with the advanced stages of hepatocellular carcinoma, and the cases with the nuclear dbpA expression had a poor prognosis. DbpA contributed more significantly to this association than YB-1. Furthermore, the T-to-G transversion in the dbpA promoter region was related to the nuclear localization of dbpA. CONCLUSION: DbpA was a more significant prognostic marker of hepatocellular carcinoma than YB-1. The T-to-G transversion in the dbpA promoter region was suggested to be a predisposing factor for the progression of hepatocellular carcinoma.