BAG-1: a novel biomarker predicting long-term survival in early-stage breast cancer

Prediction of Late Recurrence and Distant Metastasis in Early-stage Breast Cancer: Overview of Current and Emerging Biomarkers

Recently, a significant number of breast cancer (BC) patients have been diagnosed at an early stage. It is therefore critical to accurately predict the risk of recurrence and distant metastasis for better management of BC in this setting. Clinicopathologic patterns, particularly lymph node status, tumor size, and hormonal receptor status are routinely used to identify women at increased risk of recurrence. However, these factors have limitations regarding their predictive ability for late metastasis risk in patients with early BC. Emerging molecular signatures using gene expression-based approaches have improved the prognostic and predictive accuracy for this indication. However, the use of their based-scores for risk assessment has provided contradictory findings. Therefore, developing and using newly emerged alternative predictive and prognostic biomarkers for identifying patients at high- and low-risk is of great importance. The present review discusses some serum biomarkers and multigene profiling scores for predicting late recurrence and distant metastasis in early-stage BC based on recently published studies and clinical trials.

Identification of an 11-Autophagy-Related-Gene Signature as Promising Prognostic Biomarker for Bladder Cancer Patients

Simple Summary

Human bladder cancer, one of the most common cancers worldwide, is a molecularly heterogenous and complex disease. Identifying novel prognostic biomarkers and establishing new predictive signatures are important for personalized medicine and effective treatment of bladder cancer patients. Autophagy, a cell self-maintenance process that removes damaged organelles and misfolded proteins, displays both tumor promotion and suppression activities. The aim of our study is to investigate the function of autophagy-related genes in bladder cancer with the main focus on their contribution to prognostic outcome. By analyzing data obtained from The Cancer Genome Atlas (TCGA), we identified 32 autophagy-related genes that were highly associated with overall survival of bladder cancer patients. Further statistical assessment established an 11-autophagy-related-gene signature as an effective prognostic biomarker to predict the survival outcomes of bladder cancer patients.

Abstract

Background: Survival rates for highly invasive bladder cancer (BC) patients have been very low, with a 5-year survival rate of 6%. Accurate prediction of tumor progression and survival is important for diagnosis and therapeutic decisions for BC patients. Our study aims to develop an autophagy-related-gene (ARG) signature that helps to predict the survival of BC patients. Methods: RNA-seq data of 403 BC patients were retrieved from The Cancer Genome Atlas Urothelial Bladder Carcinoma (TCGA-BLCA) database. Univariate Cox regression analysis was performed to identify overall survival (OS)-related ARGs. The Lasso Cox regression model was applied to establish an ARG signature in the TCGA training cohort (N = 203). The performance of the 11-gene ARG signature was further evaluated in a training cohort and an independent validation cohort (N = 200) using Kaplan-Meier OS curve analysis, receiver operating characteristic (ROC) analysis, as well as univariate and multivariate Cox regression analysis. Results: Our study identified an 11-gene ARG signature that is significantly associated with OS, including APOL1, ATG4B, BAG1, CASP3, DRAM1, ITGA3, KLHL24, P4HB, PRKCD, ULK2, and WDR45. The ARGs-derived high-risk bladder cancer patients exhibited significantly poor OS in both training and validation cohorts. The prognostic model showed good predictive efficacy, with the area under the ROC curve (AUCs) for 1-year, 3-year, and 5-year overall survival of 0.702 (0.695), 0.744 (0.640), and 0.794 (0.658) in the training and validation cohorts, respectively. A prognostic nomogram, which included the ARGs-derived risk factor, age and stage for eventual clinical translation, was established. Conclusion: We identified a novel ARG signature for risk-stratification and robust prediction of overall survival for BC patients.

A BAG's life: Every connection matters in cancer

The members of the BCL-2 associated athanogene (BAG) family participate in the regulation of a variety of interrelated physiological processes, such as autophagy, apoptosis, and protein homeostasis. Under normal circumstances, the six BAG members described in mammals (BAG1-6) principally assist the 70 kDa heat-shock protein (HSP70) in protein folding; however, their role as oncogenes is becoming increasingly evident. Deregulation of the BAG multigene family has been associated with cell transformation, tumor recurrence, and drug resistance. In addition to BAG overexpression, BAG members are also involved in many oncogenic protein-protein interactions (PPIs). As such, either the inhibition of overloading BAGs or of specific BAG-client protein interactions could have paramount therapeutic value. In this review, we will examine the role of each BAG family member in different malignancies, focusing on their modular structure, which enables interaction with a variety of proteins to exert their pro-tumorigenic role. Lastly, critical remarks on the unmet needs for proposing effective BAG inhibitors will be pointed out.

Serum coiled-coil domain containing 25 protein as a potential screening/diagnostic biomarker for cholangiocarcinoma

Coiled-coil domain containing 25 (CCDC25) was previously reported to be upregulated in cholangiocarcinoma (CCA) tissues compared with adjacent normal tissues. The present study investigated whether serum CCDC25 level may be used as a potential marker for the diagnosis of CCA. Bioinformatics tools were used to reveal that CCDC25 is secreted into plasma/serum via a non-conventional pathway, which secretes proteins independently from the endoplasmic reticulum/golgi complex, but is yet to be fully elucidated. Subsequently, the CCDC25 levels in the sera of patients with CCA (n=141), patients with benign biliary disease (BBD; n=53) and healthy controls (HC; n=72) were measured using a quantitative dot blot assay based on the standard curve created using recombinant CCDC25 protein. The results demonstrated that the serum CCDC25 level in the CCA group (0.28±0.06 ng/µl) was significantly higher compared with that in the BBD (0.15±0.03 ng/µl) or HC (0.0017±0.0008 ng/µl) groups. Serum CCDC25 level provided an improved resolution (P=0.0001) compared with carcinoembryonic antigen (P=0.098) or carbohydrate antigen 19-9 (P=0.271) for the differential diagnosis between BBD and CCA. Receiver operating characteristic curve analysis revealed high sensitivity and specificity of serum CCDC25 level to differentiate between patients with CCA and HC (93.0 and 100%, respectively), and also to differentiate between patients with CCA and patients with BBD (75.0 and 84.0%, respectively). CCDC25 expression was further investigated in 23 CCA tissues, and CCDC25 expression in cancer tissues was moderately correlated with the serum CCDC25 level (r²=0.52, P=0.01). Among patients with CCA, serum CCDC25 level was significantly higher in patients with non-metastatic CCA compared with patients with metastatic CCA. Correspondingly, a higher serum CCDC25 level was associated with a longer overall survival time in patients with CCA. In conclusion, serum CCDC25 level may be a promising screening and diagnostic marker for the differential diagnosis of CCA.

Bag-1 Expression in Hyperplastic and Neoplastic Prostate Tissue: Is There Any Relationship with BCL-Related Proteins and Androgen Receptor Status?

Aims and Background

To evaluate the function and distribution of BAG-1 protein in hyperplastic and neoplastic prostate tissue and establish the relationship between this protein and BCL-related proteins (BCL-2 and BAX), androgen receptor (AR) expression and chromogranin A.

Methods

Twenty-eight prostatic adenocarcinomas and 16 prostate hyperplasias were included in this retrospective study. BAG-1, BCL-2, BAX, androgen receptor and chromogranin A immunostaining was performed by means of standard avidin-biotin peroxidase methods. The M30 antibody was used to identify preapoptotic and apoptotic cells. The immunohistochemical histological score (HSCORE) semi-quantative system was used to evaluate immunohistochemical staining.

Results

Statistical analysis showed a significant difference in HSCOREs of BAX, M30 and AR between the carcinoma and hyperplasia groups. Carcinomas expressed higher HSCOREs of these markers than hyperplasias. There were significant differences in nuclear and cytoplasmic BAG-1 positivity between high and low-grade carcinomas. BAG-1 expression was higher in low-grade carcinomas. In the carcinoma group there was a positive correlation (Pearson) between BCL-2 and cytoplasmic/nuclear BAG-1. In the hyperplasia group there was a negative correlation between BAX and BCL-2, and between AR and M30. We also detected a positive correlation between AR and nuclear/cytoplasmic BAG-1 and between nuclear and cytoplasmic BAG-1 in hyperplasias. BAG-1 showed the same specific basal cell localization as BCL-2 in hyperplastic and normal glands.

Conclusions

The BAG-1 protein showed a distinct distribution pattern in hyperplastic and neoplastic prostate. BAG-1 in association with BCL-2 inhibits apoptosis and may prolong the life of neoplastic cells and give them a chance to gain new oncogenic features in early carcinogenesis.

Bag-1 silencing enhanced chemotherapeutic drug-induced apoptosis in MCF-7 breast cancer cells affecting PI3K/Akt/mTOR and MAPK signaling pathways

The multifunctional anti-apoptotic Bag-1 protein has important roles in apoptosis, proteasome-mediated degradation, transcriptional regulation, and intracellular signaling. Bag-1 promotes cell survival and proliferation, and is overexpressed in breast cancer. Therefore, Bag-1-targeted therapy might be a promising strategy to treat breast cancer. However, the effects of Bag-1 silencing in combination with conventional chemotherapeutic drugs on cell viability and major signaling pathways have not yet been fully investigated in breast cancer cells. In this study, we investigated the cytotoxic effects of Bag-1 silencing, alone and in combination with cisplatin or paclitaxel treatment, in MCF-7 breast cancer cells. Bag-1 knockdown by shRNA or siRNA transfection sensitized MCF-7 cells to apoptosis induced by cisplatin or paclitaxel. Combination of Bag-1 silencing and drug treatment more potently downregulated the pro-survival PI3K/Akt/mTOR and p44/42 mitogen activated protein kinase (MAPK) pathways, and more potently upregulated the stress-activated p38 and SAPK/JNK MAPK pathways. Bag-1-silenced drug-treated cells had also highly reduced proliferative capacity, downregulated cyclin-cyclin dependent kinase complexes and upregulated tumor suppressors p21 and Rb. These results overall indicated that Bag-1 silencing enhanced cisplatin- or paclitaxel-induced cytotoxicity through multiple pathways. In conclusion, Bag-1 targeted therapy might enhance the therapeutic potential of conventional anti-cancer drugs in the treatment of breast cancer.

Copy number profiling of Oncotype DX genes reveals association with survival of breast cancer patients

Copy number variations (CNVs) are key contributors in breast cancer initiation and progression. However, to date, no CNV-based gene signature is developed for breast cancer. 21-gene Oncotype DX, a clinically validated signature, was identified using only RNA expression data in breast cancer patients. In this study, we evaluated whether CNVs of Oncotype DX genes can be used to predict the prognosis of breast cancer patients. Transcriptomic data of 547 and genomic data of 816 of breast cancer patients were downloaded from The Cancer Genome Atlas database. To establish the prognostic relevance between the CNVs of Oncotype DX genes and clinicopathological features, statistical analysis including Pearson Correlation, Fisher-exact, Chi square, Kaplan-Meier survival and Cox regression analyses were performed. 86% genes showed positive CNV-expression correlation. CNVs in 52% and 47.6% genes showed association with ER+ and PR+ status, respectively. 71% of the genes (including ERBB2, CTSV, CD68, GRB7, MKI67, MMP1, PGR, RPLP0, TFRC, BAG1, BCL2, BIRC5, FLNB, GSTM1 and SCUBE2) showed association with poor overall survival. 14% of the genes (including CTSV, RPLP0 and BIRC5) genes showed association with disease free survival. Cox regression analysis revealed ESR1, metastasis and node stage as independent prognostic factors for overall survival of breast cancer patients. The results suggested that CNV-based assay of Oncotype DX genes can be used to predict the survival of breast cancer patients. In future, identifying new gene signatures for better breast cancer prognosis using CNV level information will be worth investigating.

Breast cancer diagnosis: Imaging techniques and biochemical markers

Breast cancer is a complex disease which is found as the second cause of cancer-associated death among women. Accumulating of evidence indicated that various factors (i.e., gentical and envirmental factors) could be associated with initiation and progression of breast cancer. Diagnosis of breast cancer patients in early stages is one of important aspects of breast cancer treatment. Among of various diagnosis platforms, imaging techniques are main diagnosis approaches which could provide valuable data on patients with breast cancer. It has been showed that various imaging techniques such as mammography, magnetic resonance imaging (MRI), positron-emission tomography (PET), Computed tomography (CT), and single-photon emission computed tomography (SPECT) could be used for diagnosis and monitoring patients with breast cancer in various stages. Beside, imaging techniques, utilization of biochemical biomarkers such as proteins, DNAs, mRNAs, and microRNAs could be employed as new diagnosis and therapeutic tools for patients with breast cancer. Here, we summarized various imaging techniques and biochemical biomarkers could be utilized as diagnosis of patients with breast cancer. Moreover, we highlighted microRNAs and exosomes as new diagnosis and therapeutic biomarkers for monitoring patients with breast cancer.

Cytoplasmic Localization of BAG-1 in Leukoplakia and Carcinoma of the Tongue: Correlation with p53 and C-Erbb2 in Carcinoma

Background

The present study evaluated the clinical significance of BAG-1, an antiapoptotic protein, in leukoplakia and carcinoma of the tongue.

Methods

BAG-1 expression was evaluated by immunohistochemistry in paraffin-embedded tissues of leukoplakia (n=25) and carcinoma of the tongue (n=61).

Results

Cytoplasmic expression was predominantly seen in 80% and 70% of patients with leukoplakia and carcinoma, respectively. BAG-1 expression was found to be significantly lower in tobacco users than in non-tobacco users. BAG-1 expression in tobacco-using leukoplakia and carcinoma patients was compared by grouping the carcinoma patients according to lymph node status and disease stage. Carcinoma patients with tumor-positive lymph nodes had significantly lower BAG-1 expression than patients with negative lymph nodes and leukoplakia. Further, a trend towards an inverse correlation was observed with p53 and c-erbB2. In univariate and multivariate survival analysis, patient subgroups with 2+ or 3+ marker positivity (BAG-1 negativity, p53 and c-erbB2 positivity) had a reduced overall survival compared with patient subgroups with 1+ marker positivity or negativity.

Conclusion

BAG-1 negativity in association with p53 and c-erbB2 positivity identified a subgroup of tongue cancer patients with an aggressive phenotype. Hence, an antiapoptotic protein, BAG-1, was found to be down-regulated in chewing-tobacco-mediated tongue carcinogenesis.

BAG-1 as a biomarker in early breast cancer prognosis: a systematic review with meta-analyses

BACKGROUND

The co-chaperone protein Bcl-2-associated athanogene-1 (BAG-1) is overexpressed in breast cancer and has been incorporated in the oncotype DX and PAM50 breast cancer prognostic assays. Bcl-2-associated athanogene-1 exists as multiple protein isoforms that interact with diverse partners, including chaperones Hsc70/Hsp70, Ser/Thr kinase Raf-1 and Bcl-2, to promote cancer cell survival. The BAG-1L isoform specifically binds to and increases the transcriptional activity of oestrogen receptor in cells, and in some, but not all studies, BAG-1 expression is predictive of clinical outcome in breast cancer.

METHODS

A systematic review of published studies reporting BAG-1 (mRNA and/or protein) expression and clinical outcome in early breast cancer. The REporting Recommendations for Tumour MARKer and Prognostic Studies (REMARK) criteria were used as a template against which data were assessed. Meta-analyses were performed for studies that provided a hazard ratio and 95% confidence intervals for clinical outcomes including disease-free survival or breast cancer-specific survival from univariate analysis.

RESULTS

Eighteen studies used differing methodologies and reported on differing outcomes. Meta-analyses were only possible on results from a subset of reported studies. Meta-analyses suggested improved outcome with high BAG-1 mRNA and high BAG-1 nuclear expression by immunohistochemisty.

CONCLUSIONS

Increased levels of BAG-1 are associated with better breast cancer outcomes.

A combination of trastuzumab and BAG-1 inhibition synergistically targets HER2 positive breast cancer cells

Treatment of HER2+ breast cancer with trastuzumab is effective and combination anti-HER2 therapies have demonstrated benefit over monotherapy in the neoadjuvant and metastatic settings. This study investigated the therapeutic potential of targeting the BAG-1 protein co-chaperone in trastuzumab-responsive or -resistant cells. In the METABRIC dataset, BAG-1 mRNA was significantly elevated in HER2+ breast tumors and predicted overall survival in a multivariate analysis (HR = 0.81; p = 0.022). In a breast cell line panel, BAG-1 protein was increased in HER2+ cells and was required for optimal growth as shown by siRNA knockdown. Overexpression of BAG-1S in HER2+ SKBR3 cells blocked growth inhibition by trastuzumab, whereas overexpression of a mutant BAG-1S protein (BAG-1S H3AB), defective in binding HSC70, potentiated the effect of trastuzumab. Injection of a Tet-On SKBR3 clone, induced to overexpress myc-BAG-1S into the mammary fat pads of immunocompromised mice, resulted in 2-fold larger tumors compared to uninduced controls. Induction of myc-BAG-1S expression in two Tet-On SKBR3 clones attenuated growth inhibition by trastuzumab in vitro. Targeting endogenous BAG-1 by siRNA enhanced growth inhibition of SKBR3 and BT474 cells by trastuzumab, while BAG-1 protein-protein interaction inhibitor (Thio-S or Thio-2) plus trastuzumab combination treatment synergistically attenuated growth. In BT474 cells this reduced protein synthesis, caused G1/S cell cycle arrest and targeted the ERK and AKT signaling pathways. In a SKBR3 subpopulation with acquired resistance to trastuzumab BAG-1 targeting remained effective and either Thio-2 or BAG-1 siRNA reduced growth more compared to trastuzumab-responsive parental cells. In summary, targeting BAG-1 function in combination with anti-HER2 therapy might prove beneficial.

The interleukin-6/Janus kinase/STAT3 pathway in pleomorphic adenoma and carcinoma ex pleomorphic adenoma of the lacrimal gland

PURPOSE

Pleomorphic adenoma (PA) is the most common tumour of the lacrimal gland, but very little is known about its biology. It has a tendency to recur and an ability to transform into the high-grade malignancy carcinoma ex pleomorphic adenoma (ca-ex-PA), which is also largely unexplored. In this study, we examine the expression of the interleukin-6/Janus kinase/STAT3 (IL-6/JAK/STAT3) pathway components in PA and ca-ex-PA.

METHODS

Sixteen PAs and two ca-ex-PAs were examined with immunohistochemistry. Seven PAs were subjected to microdissection and subsequent qPCR.

RESULTS

The IL-6/JAK/STAT3 pathway was overexpressed in PA compared to normal lacrimal gland. Overexpression of phosphorylated JAK1 (p-JAK1) and cyclin D1 was significantly overexpressed in ductal cells compared with myoepithelial cells in PA. A shift from p-JAK1 to p-JAK2 and p-Tyk2 overexpression was seen between PA and ca-ex-PA, combined with a high p-STAT3 expression in the latter.

CONCLUSION

The IL-6/JAK/STAT3 pathway is overexpressed in PA, and this overexpression was even more pronounced in ca-ex-PA, with a shift in the JAKs mediating STAT3 phosphorylation. Future studies are needed to clarify whether PA and ca-ex-PA could be treated with targeted therapy directed against components of the IL-6/JAK/STAT3 pathway.

The Bag-1 inhibitor, Thio-2, reverses an atypical 3D morphology driven by Bag-1L overexpression in a MCF-10A model of ductal carcinoma in situ

Mammary MCF-10A cells seeded on reconstituted basement membrane form spherical structures with a hollow central lumen, termed acini, which are a physiologically relevant model of mammary morphogenesis. Bcl-2-associated athanogene 1 (Bag-1) is a multifunctional protein overexpressed in breast cancer and ductal carcinoma in situ. When present in the nucleus Bag-1 is predictive of clinical outcome in breast cancer. Bag-1 exists as three main isoforms, which are produced by alternative translation initiation from a single mRNA. The long isoform of Bag-1, Bag-1L, contains a nuclear localisation sequence not present in the other isoforms. When present in the nucleus Bag-1L, but not the other Bag-1 isoforms, can interact with and modulate the activities of estrogen-, androgen- and vitamin D-receptors. Overexpression of Bag-1 mRNA in MCF-10A is known to produce acini with luminal filling reminiscent of ductal carcinoma in situ. As this mRNA predominantly overexpresses the short isoform of Bag-1, Bag-1S, we set out to examine whether the nuclear Bag-1L isoform is sufficient to drive premalignant change by developing a Bag-1L-overexpressing MCF-10A model. Two clones differentially overexpressing Bag-1L were grown in two-dimensional (2D) and three-dimensional (3D) cultures and compared with an established model of HER2-driven transformation. In 2D cultures, Bag-1L overexpression reduced proliferation but did not affect growth factor responsiveness or clonogenicity. Acini formed by Bag-1L-overexpressing cells exhibited reduced luminal clearing when compared with controls. An abnormal branching morphology was also observed which correlated with the level of Bag-1L overexpression, suggesting further malignant change. Treatment with Thio-2, a small-molecule inhibitor of Bag-1, reduced the level of branching. In summary, 3D cultures of MCF-10A mammary epithelial cells overexpressing Bag-1L demonstrate a premalignant phenotype with features of ductal carcinoma in situ. Using this model to test the small-molecule Bag-1 inhibitor, Thio-2, reveals its potential to reverse the atypical branched morphology of acini that characterizes this premalignant change.

BAG-1/SODD, HSP70, and HSP90 are potential prognostic markers of poor survival in node-negative breast carcinoma

The objective of this study was to analyze the expression and clinical role of 13 signaling molecules in a large cohort of breast carcinoma patients with long follow-up period. Breast carcinomas (n=410) were analyzed for protein expression of phosphorylated mitogen-activated protein kinases (p-ERK, p-JNK, p-p38) and phosphoinositide 3-kinase signaling pathway proteins (p-AKT, p-mTOR, p-p70S6K); the BAG family proteins BAG-1 and BAG-4/SODD; the antiapoptotic protein Bcl-2; the inhibitor of apoptosis family member Survivin; and the heat shock protein family members HSP27, HSP70, and HSP90. Protein expression was studied for association with clinicopathological parameters and survival. Significantly higher expression of p-AKT (P<.001), p-mTOR (P<.001), p-p70S6K (P<.001), Bcl-2 (P<.001), BAG-4/SODD (P<.001), HSP27 (P<.001), HSP70 (P=.012), HSP90 (P<.001), and Survivin (P=.004) was found in infiltrating ductal and lobular carcinomas compared to mucinous carcinomas. Bcl-2 expression was significantly higher in grades 1 and 2 compared to grade 3 carcinomas (P<.001). p-AKT expression was higher in tumors more than 2cm (P=.027), whereas p-mTOR expression was lowest in tumors more than 5cm (P=.019). Higher BAG-4/SODD, HSP70, and HSP90 expression was associated with poor overall survival (P=.016, P=.039, and P=.023, respectively) in univariate analysis, whereas the only independent prognosticator in Cox multivariate survival analysis was tumor diameter (P=.003). In conclusion, BAG-4/SODD, HSP70, and HSP90 are potential prognostic markers in node-negative breast carcinoma that merit further research.

The proteasome factor Bag101 binds to Rad22 and suppresses homologous recombination

Although RAD52 plays a critical role in the initiation of homologous recombination (HR) by facilitating the replacement of RPA with RAD51, the mechanism controlling RAD52 remains elusive. Here, we show that Bag101, a factor implicated in proteasome functioning, regulates RAD52 protein levels and subsequent HR. LC-MS/MS analysis identified Bag101 which binds to Rad22, the fission yeast homologue of RAD52. Bag101 reduced HR frequency through its overexpression and conversely, HR frequencies were enhanced when it was deleted. Consistent with this observation, Rad22 protein levels was reduced in cells where bag101 was overexpressed even when Rad22 transcription was up-regulated, suggesting the operation of proteasome-mediated Rad22 degradation. Indeed, Rad22 protein levels were stabilized in proteasome mutants. Rad22 physically interacted with the BAG domain of Bag101, and a lack of this domain enhanced HR frequency. Similarly, radiation exposure triggered the dissociation of these proteins so that Rad22 was stabilized and able to enhance HR.

Overexpressed nuclear BAG-1 in human hepatocellular carcinoma is associated with poor prognosis and resistance to doxorubicin

Bcl-2-associated athanogene-1 (BAG-1) is a multifunctional anti-apoptotic protein which regulates an array of cellular processes, including apoptosis, signaling, proliferation, transcription, and cell motility and has been reported to be over-expressed in a number of human malignancies. To investigate the possible involvement of BAG-1 in tumorigenesis of hepatocellular carcinoma (HCC), we performed Western blot analysis in eight paired samples of HCC and adjacent peritumoral tissues and immunohistochemistry in 65 paraffin sections of HCC, which both showed an enhanced expression of nuclear BAG-1 isoform in HCC tissues. Statistical analysis confirmed that overexpression of nuclear BAG-1 in HCC tissues was significantly associated with histological grading (P < 0.001), poor prognosis (P = 0.004), and was found to be an independent prognostic indicator for HCC (P = 0.023). We also noted that BAG-1 was overexpressed in four HCC cell lines compared with a normal hepatocyte cell line, and BAG-1 overexpression increased resistance of HCC cells to doxorubicin, a common chemotherapeutic agent for HCC. Furthermore, we observed that knock down of BAG-1 with siRNA in HepG2 cells increased the chemosensitivity of cells, a process mediated through inhibition of doxorubicin-triggered NF-κB activation; and knock down of BAG-1 suppressed proliferation and cell cycle transition of HepG2 cells. In consequence, our results for the first time indicated that BAG-1 was dysregulated in HCC and suppression of BAG-1 expression which resulted in inhibiting of NF-κB signaling might be developed into a new strategy in HCC therapy.

Bcl-2 associated anthanogen-1 (Bag-1) expression and prognostic value in pancreatic head and periampullary cancer

The expression of anti-apoptosis gene Bcl-2 associated anthanogen-1 (Bag-1), has been associated with outcome in several cancer types, however its prognostic role in pancreatic cancer is unknown. Aim was therefore to evaluate expression of Bag-1 in two anatomically closely related however prognostically different tumours, pancreatic head- and periampullary cancer and correlate expression with outcome. Bag-1 protein expression was studied by immunohistochemistry on original paraffin embedded tissue from 217 patients with microscopic radical resection (R0) of adenocarcinoma of the pancreatic head or periampullary region. Expression was assessed for associations with recurrence free- (RFS), cancer specific- (CSS), overall survival (OS) and conventional prognostic factors. Nuclear Bag-1 was present in 80% of tumours. In 40% Bag-1 resided in the cytosol, which was almost exclusively associated with nuclear expression. Nuclear Bag-1 protein was identified as an independent factor predicting a favourable outcome following radical resection of pancreatic head cancer. Eighteen percent of patients with nuclear Bag-1 were recurrence free and alive 5 years following surgery compared to none of the patients lacking expression. In periampullary cancer Bag-1 was not associated with outcome. In conclusion, Bag-1 was present in the majority of both pancreatic head- and periampullary cancers. However it was only identified as a discriminator of outcome in pancreatic head cancer.

BAG-1 diversely affects steroid receptor activity

Part of the cellular and physiological functions of BAG-1 (Bcl-2-associated athanogene 1) has been ascribed to the ability of this hsp70 (heat-shock protein 70) co-chaperone to regulate steroid receptor activity. BAG-1 has been reported to inhibit the GR (glucocorticoid receptor) and stimulate the androgen receptor, but to leave the activity of the MR (mineralocorticoid receptor) unchanged. Given the high homology between the MR and GR, this disparity in the actions of BAG-1 is surprising. In the present study, we analysed the effect of BAG-1 on the activity of the closely related PR (progesterone receptor). Similarly to the GR, the transcriptional activity of the PR is inhibited by the long and middle isoforms of BAG-1, BAG-1L and BAG-1M, but not by the short isoform, BAG-1S. We found this inhibition to require the hsp70-binding domain of BAG-1. To shed light on the mechanisms that could explain BAG-1's differential actions on steroid receptors, we tested the binding of BAG-1M to the PR. Mutational analyses of the PR and BAG-1M revealed that the mode of interaction and BAG-1M-mediated inhibition of the PR differs from the reported scenario for the GR. Surprisingly, we also found binding of BAG-1M to the MR. In addition, BAG-1M was able to inhibit the transcriptional activity of the MR. These data entail a reappraisal of the physiological actions of BAG-1M on steroid receptor activity.

Coexpression of PDGFR-alpha, PDGFR-beta and VEGF as a prognostic factor in patients with hepatocellular carcinoma

AIMS

To evaluate the prognostic value of vascular endothelial growth factor (VEGF), platelet-derived growth factor receptor-alpha (PDGFR-a) and beta (PDGFR-ß) expression in patients with hepatocellular carcinoma (HCC).?

METHODS

The expression of PDGFR-a, PDGFR-ß and VEGF in 63 HCC patients who underwent curative resection was examined by immunohistochemistry (IHC). The correlations between the expression of these biomarkers and the clinicopathological characteristics were analyzed. Patient survival was analyzed by univariate analysis and Cox proportional hazards model.?

RESULTS

Univariate survival analysis showed that PDGFR-a or PDGFR-ß overexpression was of no prognostic significance in predicting disease-free survival (DFS) and overall survival (OS) (p>0.05), while VEGF overexpression and PDGFR-a/PDGFR-ß/VEGF coexpression were significantly correlated with worse DFS and poorer OS in HCC patients (p<0.05). More importantly, PDGFR-a/PDGFR-ß/VEGF coexpression was an independent prognostic marker for poor survival as indicated by multivariate Cox regression analysis (DFS, hazard ratio 3.122, p=0.001; OS, hazard ratio 4.260, p=0.000).?

CONCLUSIONS

Coexpression of PDGFR-a, PDGFR-ß and VEGF could be considered an independent prognostic biomarker for predicting DFS and OS in HCC patients. This result could be used to identify patients at a higher risk of tumor recurrence and poor prognosis, and help to select therapeutic schemes for the treatment of HCC.

Epidermal growth factor receptor (EGFR) mutation and p-EGFR expression in resected non-small cell lung cancer

Lung cancer, specifically non-small cell lung cancer (NSCLC), is a leading cause of mortality worldwide. In China, a dramatic increase in the incidence of NSCLC is expected in the next 20 years (Molina et al. Mayo Clin Proc. 2008;83:584–594). Mutated epidermal growth factor receptor (EGFR) status is a known predictor of response to tyrosine kinase inhibitors (TKIs), and immunohistochemistry may be a less costly way of predicting presence of mutation. In this study, mutation analysis of EGFR in 218 cases of NSCLC was performed. One hundred thirty tissue samples were examined via immunohistochemistry of p-EGFR (Y1045 and Y1068) and correlated with mutation status. Mutations were seen in 29% of patients, and were correlated with female sex, nonsmoking history, and adenocarcinoma histology. Phosphorylation at Y1045 was noted in 52% of cases, but in 71% of cases with EGFR mutation (P = .003). Phosphorylation of Y1068 was seen in 55% of cases but in 73% of cases with EGFR mutation (P = .006). This study correlating EGFR mutation with p-EGFR expression in resected NSCLC is one of the largest to date, although TKI response could not be assessed. The data show that, among Chinese patients, detection of p-1045 and p-1068 expression with immunohistochemistry predicts EGFR mutations. Immunohistochemical analysis of p-EGFR may be useful to predict responses to TKI therapy, although future studies are necessary.

IGFBP3 and BAG1 enhance radiation-induced apoptosis in squamous esophageal cancer cells

Identification of reliable markers of radiosensitivity and the key molecules that enhance the susceptibility of esophageal cancer cells to anticancer treatments would be highly desirable. To identify molecules that confer radiosensitivity to esophageal squamous carcinoma cells, we assessed the radiosensitivities of the TE-5, TE-9 and TE-12 cloneA1 cell lines. TE-12 cloneA1 cells showed significantly greater susceptibility to radiotherapy at 5 and 10Gy than either TE-5 or TE-9 cells. Consistent with that finding, 24h after irradiation (5Gy), TE-12 cloneA1 cells showed higher levels of caspase 3/7 activity than TE-5 or TE-9 cells. When we used DNA microarrays to compare the gene expression profiles of TE-5 and TE-12 cloneA1 cells, we found that the mRNA and protein expression of insulin-like growth factor binding protein 3 (IGFBP3) and Bcl-2-associated athanogene 1 (BAG1) was five or more times higher in TE-12 cloneA1 cells than TE-5 cells. Conversely, knocking down expression of IGFBP3 and BAG1 mRNA in TE-12 cloneA1 cells using small interfering RNA (siRNA) significantly reduced radiosensitivity. These data suggest that IGFBP3 and BAG1 may be key markers of radiosensitivity that enhance the susceptibility of squamous cell esophageal cancer to radiotherapy. IGFBP3 and BAG1 may thus be useful targets for improved and more individualized treatments for patients with esophageal squamous cell carcinoma.

[BAG family gene and its relationship with lung adenocarcinoma susceptibility]

BACKGROUND AND OBJECTIVE

BAG genes (Bcl-2-associated athanogene) belong to a recently discovered multifunctional anti-apoptosis gene family that regulate various physiological processes which include apoptosis, tumorigenesis, neural differentiation, stress response and cell cycle and so on. The expression status of BAG family genes are related to certain tumor incidence and prognosis. The aim of this study is to explore the association of the BAG family gene expression status with the susceptibility of lung adenocarcinoma.

METHODS

The gene expression data of BAG family genes from 29 cases of lung adenocarcinoma tissues and matched pericancerous lung tissues were generated by microarray chips. Cox regression was used to analyze the association between the expression of BAG family genes and the susceptibility of lung adenocarcinoma and the results were verified by GEO database.

RESULTS

The expression levels of BAG-1, BAG-2, BAG-5 in cancer tissues were significantly downregulated compared with matched pericancerous lung tissues and were protective factors of lung adenocarcinoma (P < 0.05, OR < 1); while the expression level of BAG-4 in cancer tissues were remarkably upregulated compared with the matched pericancerous lung tissues and was risk factor of lung adenocarcinoma (P < 0.05, OR > 1).

CONCLUSIONS

BAG-1, BAG-2, BAG-5 might be the potential protective factors while BAG-4 is possible risk factor of lung adenocarcinoma.

BAG3 protein delocalisation in prostate carcinoma

Despite the progressive increase of early diagnosis, a subset of prostate cancers show a metastasizing and lethal course, not always predictable upon the traditional prognostic parameters. The object of this study was to investigate the role of the survival co-chaperone protein BAG3 as a new prognostic marker for prostate cancer. BAG3 was detected by immunohistochemistry in 55 specimens of surgically removed prostate carcinomas and in 15 surgical specimens of non-neoplastic prostate tissues. Results were compared with clinic-pathological data and outcome of patients and statistically evaluated. BAG3 resulted expressed in all the cases: Non-neoplastic prostate tissue showed a cytoplasmatic staining with apical reinforcement, a finding which appears consistent with the reported connection of the protein with the membrane focal cell-adhesion complexes. In prostate carcinomas, BAG3 showed a progressive decrease of the expression level from well- to low-differentiated carcinoma, coupled with the loss of polarisation of the signal in metastasizing cases. These results indicate that BAG3 intra-cytoplasmic delocalisation is a specific feature of cancer versus non-neoplastic prostate and a candidate new marker for prediction of prostate cancer invasiveness and behaviour.

Expressions of the anti-apoptotic genes Bag-1 and Bcl-2 in colon cancer and their relationship

BACKGROUND

The aims of this study were to investigate the expressions and significance of the antiapoptotic genes Bag-1 and Bcl-2 in colon cancer and to evaluate their relationship.

METHODS

The expressions of Bag-1 and Bcl-2 were examined in 128 colon cancer and 20 normal colon tissue samples by reverse-transcription polymerase chain reaction and immunohistochemical technique (streptavidin-biotin-peroxidase complex method).

RESULTS

Bag-1 and Bcl-2 were expressed in colorectal cancer tissues but not in normal colorectal tissues by reverse-transcription polymerase chain reaction. The expression of Bag-1 in colon cancer was closely correlated with pathologic grade, distance metastasis, Duke stage, and prognosis, but it had no effect on the pathologic type, tumor diameter, depth of invasion, and lymphoid node metastasis of the cancer. By contrast, Bcl-2 had no significant correlation with all the clinical and pathologic factors. There was a positive correlation between Bag-1 and Bcl-2 in the development of colon cancer.

CONCLUSIONS

High expressions of Bag-1 and Bcl-2 proteins in colon cancer were found. They might be regarded as biomarkers for the diagnosis of the early stage of colon cancer. In addition, they have significant relevance for the prognosis of colon cancer.

Altered expression of p120catenin predicts poor outcome in invasive breast cancer

PURPOSE

The study focuses on p120catenin, a regulator of cell adhesion, which has previously been described in many malignancies and suggested with a role in invasion and metastatic behaviour. In this study, we investigate the role of altered immunoexpression of p120catenin isoforms in the prognosis of invasive breast cancer (n = 351).

METHODS

We used cDNA microarrays to screen differences in gene expression in invasive breast cancer in general, and between local and metastasized disease particularly. On this basis, we performed p120catenin immunohistochemistry in order to confirm the prognostic value of p120catenin isoforms on tissue microarrays comprising 341 patients from the era of mammographic screening, directed to modern surgical and oncological treatments, and followed-up for maximum of 20 years.

RESULTS

In cDNA microarray analysis, p120catenin was discovered down-regulated along with E-cadherin and alpha-catenin. In addition, p120catenin distinguished metastasized breast cancer from local disease. Immunohistochemistry confirmed the value of p120catenin as an independent prognosticator of breast cancer survival. In our results, p120catenin was associated with 3.7-fold risk of breast cancer death in multivariate Cox's regression analyses adjusted for the established prognosticators of breast cancer (p = 0.039). Particularly, the long isoform of p120catenin predicted metastatic disease (p = 0.029).

CONCLUSION

The present paper is the first report on p120catenin in invasive breast cancer based on a well-characterized patient material with long-term follow-up. We observed altered expression of p120catenin isoforms in invasive breast cancer and, in our material, the decrease in p120 immunoexpression was significantly associated with poor outcome of disease.

Nuclear or cytoplasmic localization of Bag-1 distinctly correlates with pathologic behavior and outcome of gastric carcinomas

Bag-1 is an antiapoptotic protein with its altered expression and localization in malignancies. To clarify the role of Bag-1 in gastric carcinogenesis, its expression was examined by immunohistochemistry and in situ hybridization on a tissue microarray containing gastric carcinomas, adjacent nonneoplastic mucosa (NNM), adenomas, intestinal metaplasia (IM), or gastritis. Gastric carcinoma tissue and cell lines were studied for Bag-1 expression by Western blot and reverse transcriptase-polymerase chain reaction (RT-PCR). The results demonstrated that Bag-1 proteins were differentially expressed in the nucleus or cytosol of MKN28, AGS, MKN45, KATO-III, or HGC-27 cell lines, despite similar levels of messenger RNA (mRNA) expression. The Bag-1 mRNA overexpression was detectable in 73.3% of 15 gastric carcinomas without significant difference in its encoding products' levels. The nuclear Bag-1 expression gradually decreased from gastritis, IM, adenoma to carcinoma (P < .05), and negatively correlated with lymphatic invasion or lymph node metastasis, cytoplasmic Bag-1 expression, negative parafibromin expression, and poor prognosis (P < .05). Cytoplasmic Bag-1 was weakly immunoreactive in carcinomas, compared with gastritis (P < .05), and positively associated with invasive depth and poor prognosis of the carcinoma (P < .05). The positive rate of Bag-1 mRNA expression was higher in adjacent IMs than carcinomas or adjacent NNM (P < .05). Bag-1 mRNA was expressed more in carcinomas from female patients than the male counterparts (P < .05). There was a positive correlation of Bag-1 mRNA expression with invasive depth and venous invasion (P < .05). Our study indicated that aberrant expression and subcellular distribution of Bag-1 might play an important role in the malignant transformation of gastric epithelial cells and should be considered as a biomarker for gastric carcinogenesis, subsequent progression, and prognosis.

The BAG-1 cochaperone is a negative regulator of p73-dependent transcription

High-level expression of Bcl-2 associated athanogene (BAG-1) protects cancer cells from stress-induced cell death and growth inhibition. These protective effects of BAG-1 are dependent on interactions with the HSC70 and HSP70 chaperones. However, the key stress-response molecules that are regulated by a BAG-1/chaperone mechanism have not been identified. In this study, we investigated the effects of BAG-1 overexpression on the function of p53 family proteins, p53, p63 and p73. Overexpression of BAG-1 isoforms interfered with the transactivating activity of p73 and p63, but had modest and variable effects on p53-dependent transcription. p73 and BAG-1 interacted in intact cells and overexpression of BAG-1 decreased the expression of p73. siRNA-mediated ablation of endogenous BAG-1 increased the activity of a p73-responsive promoter and this was reversed by knock-down of p73. The ability of BAG-1 to modulate p73 activity and expression, and to interact with p73 were dependent on amino acid residues required for the interaction of BAG-1 with HSC70 and HSP70. These results show that BAG-1 inhibits the transactivating functions of p73 and provide new insight into the mechanisms that control the expression of p73. Inhibition of p73 function may be one mechanism that contributes to the pro-survival activity of BAG-1.

Multiple, but concerted cellular activities of the human protein Hap46/BAG-1M and isoforms

The closely related human and murine proteins Hap46/BAG-1M and BAG-1, respectively, were discovered more than a decade ago by molecular cloning techniques. These and the larger isoform Hap50/BAG-1L, as well as shorter isoforms, have the ability to interact with a seemingly unlimited array of proteins of completely unrelated structures. This problem was partially resolved when it was realized that molecular chaperones of the hsp70 heat shock protein family are major primary association partners, binding being mediated by the carboxy terminal BAG-domain and the ATP-binding domain of hsp70 chaperones. The latter, in turn, can associate with an almost unlimited variety of proteins through their substrate-binding domains, so that ternary complexes may result. The protein folding activity of hsp70 chaperones is affected by interactions with Hap46/BAG-1M or isoforms. However, there also exist several proteins which bind to Hap46/BAG-1M and isoforms independent of hsp70 mediation. Moreover, Hap46/BAG-1M and Hap50/BAG-1L, but not the shorter isoforms, can bind to DNA in a sequence-independent manner by making use of positively charged regions close to their amino terminal ends. This is the molecular basis for their effects on transcription which are of major physiological relevance, as discussed here in terms of a model. The related proteins Hap50/BAG-1L and Hap46/BAG-1M may thus serve as molecular links between such diverse bioactivities as regulation of gene expression and protein quality control. These activities are coordinated and synergize in helping cells to cope with conditions of external stress. Moreover, they recently became markers for the aggressiveness of several cancer types.

BAG-1 predicts patient outcome and tamoxifen responsiveness in ER-positive invasive ductal carcinoma of the breast

BAG-1 (bcl-2-associated athanogene) enhances oestrogen receptor (ER) function and may influence outcome and response to endocrine therapy in breast cancer. We determined relationships between BAG-1 expression, molecular phenotype, response to tamoxifen therapy and outcome in a cohort of breast cancer patients and its influence on tamoxifen sensitivity in MCF-7 breast cancer cells in vitro. Publically available gene expression data sets were analysed to identify relationships between BAG-1 mRNA expression and patient outcome. BAG-1 protein expression was assessed using immunohistochemistry in 292 patients with invasive ductal carcinoma and correlated with clinicopathological variables, therapeutic response and disease outcome. BAG-1-overexpressing MCF-7 cells were treated with antioestrogens to assess its effects on cell proliferation. Gene expression data demonstrated a consistent association between high BAG-1 mRNA and improved survival. In ER+ cancer (n=189), a high nuclear BAG-1 expression independently predicted improved outcome for local recurrence (P=0.0464), distant metastases (P=0.0435), death from breast cancer (P=0.009, hazards ratio 0.29, 95% CI: 0.114-0.735) and improved outcome in tamoxifen-treated patients (n=107; P=0.0191). BAG-1 overexpression in MCF-7 cells augmented antioestrogen-induced growth arrest. A high BAG-1 expression predicts improved patient outcome in ER+ breast carcinoma. This may reflect both a better definition of the hormone-responsive phenotype and a concurrent increased sensitivity to tamoxifen.

Bag-1 proteins in oral squamous cell carcinoma

Bag-1 is an anti-apoptotic protein that exhibits altered expression in many malignancies, including oral squamous cell carcinoma. The bag-1 gene gives rise to different protein products with different subcellular localisations through alternative translational initiation sites. In oral squamous cell carcinoma, cytoplasmic expression has been associated with metastasis to regional lymph nodes and poor prognosis. In contrast, the longest Bag-1 isoform is nuclear and may regulate differentiation in oral epithelium. In this review, the functions of the three isoforms of Bag-1 expressed in oral epithelial cells are discussed in relation to their contribution to oral carcinogenesis.

Expression patterns and prognostic value of Bag-1 and Bcl-2 in breast cancer

Introduction

Bcl-2 antanogene-1 (Bag-1) binds the anti-apoptotic mediator Bcl-2, and enhances its activity. Bcl-2 and Bag-1 are associated with chemotherapy resistance in cancer cells. Drugs that target Bcl-2 are currently in clinical development. The purpose of the present study was to examine expression patterns of Bag-1 in a large cohort of breast tumors and to assess the association with Bcl-2, estrogen receptor, progesterone receptor and Her2/neu, and other clinical/pathological variables.

Methods

Tissue microarrays containing primary specimens from 638 patients with 10-year follow-up were employed, and the expression of Bag-1, Bcl-2, estrogen receptor, progesterone receptor and Her2/neu was assessed using our automated quantitative analysis method. We used cytokeratin to define pixels as breast cancer (tumor mask) within the array spot, and we measured biomarker expression within the mask using Cy5 conjugated antibodies.

Results

High Bcl-2 expression was associated with improved survival in the entire cohort and in the node-positive subset (P = 0.008 and P = 0.002, respectively). High Bag-1 expression was associated with improved survival in the node-positive subset (P = 0.006). On multivariable analysis, neither Bcl-2 nor Bag-1 retained their independence as prognostic markers. Strong associations were found between Bag-1, Bcl-2, estrogen receptor and progesterone receptor.

Conclusion

Bag-1 and Bcl-2 expression in breast tumors is associated with improved outcome and steroid receptor positivity. Evaluation of Bcl-2 and Bag-1 expression in breast cancer may identify a subset of patients with a favorable prognosis, who might not benefit from chemotherapy or who might benefit from Bcl-2 targeting agents in addition to antihormonal therapy.

Expression of BAG-1 protein correlates with aggressive behavior of prostate cancers

BACKGROUND

Differences in tumor behavior, ranging from indolent to aggressive, create a need for novel prognostic biomarkers. BAG-1 is a co-chaperone that regulates the activity of Hsp70, Bcl-2, Raf-1, growth factor, and steroid receptors (e.g., the Androgen Receptor).

METHODS

Using immunohistochemical method, we explored BAG-1 expression in prostate cancers and its association with clinicopathological parameters.

RESULTS

BAG-1 immunostaining was elevated in prostate cancer compared to normal prostatic epithelium. Higher nuclear BAG-1 in hormone-refractory (n = 34) compared to localized untreated tumors (n = 58) (P < 0.0001) suggested that upregulation of the nuclear isoform may contribute to disease progression. In 64 early-stage patients (T2N0M0) treated with external-beam irradiation, cytosolic BAG-1 correlated with higher pretreatment levels of serum Prostate specific antigen (P = 0.04) and shorter time to disease progression (P = 0.00004).

CONCLUSIONS

Increased cytosolic and nuclear BAG-1 expression may denote more aggressive variants of prostate cancer.

Role of oncoproteomics in the personalized management of cancer

Oncoproteomics is the term used to describe the application of proteomic technologies in oncology and parallels the related field of oncogenomics. It is now contributing to the development of personalized management of cancer. Proteomic technologies are used for the identification of biomarkers in cancer, which will facilitate the integration of diagnosis and therapy of cancer. Molecular diagnostics, laser capture microdissection and protein biochips are among the technologies that are having an important impact on oncoproteomics. The discovery of protein patterns developed by the US Food and Drug Administration/National Cancer Institute Clinical Proteomics Program is capable of distinguishing cancer and disease-free states with high sensitivity and specificity and will also facilitate the development of personalized therapy of cancer. Examples of application are given for breast and prostate cancer and a selection of companies and their collaborations that are developing application of proteomics to personalized treatment of cancer are discussed. Continued refinement of techniques and methods to determine the abundance and status of proteins in vivo holds great promise for the future study of normal cells and the pathology of associated neoplasms. Personalized cancer therapy is expected to be in the clinic by the end of the first decade of the 21st century.

Hsp70 Chaperone as a Survival Factor in Cell Pathology

Heat shock protein Hsp70 is implicated in the mechanism of cell reaction to a variety of cytotoxic factors. The protective function of Hsp70 is related to its ability to promote folding of nascent polypeptides and to remove denatured proteins. Many types of cancer cells contain high amounts of Hsp70, whose protective capacity may pose a problem for therapy in oncology. Hsp70 was shown to be expressed on the surface of cancer cells and to participate in the presentation of tumor antigens to immune cells. Therefore, the chaperone activity of Hsp70 is an important factor that should be taken into consideration in cancer therapy. The protective role of Hsp70 is also evident in neuropathology. Many neurodegenerative processes are associated with the accumulation of insoluble aggregates of misfolded proteins in neural cells. These aggregates hamper intracellular transport, inhibit metabolism, and activate apoptosis through diverse pathways. The increase of Hsp70 content results in the reduction of aggregate size and number and ultimately enhances cell viability.

Estrogen receptor beta (ERbeta) protein expression correlates with BAG-1 and prognosis in brain glial tumours

Estrogen receptor beta (ERbeta) is an important mediator of estrogen function in a variety of tissues. Its expression declines in breast, ovarian, prostatic and colon carcinomas as well as in astrocytic tumours. BAG-1 is a multifunctional protein with an important role in neoplasia and is possibly regulated by estrogen receptors. One of the direct targets of BAG-1 is HSP70. The purpose of this study was to analyse the expression pattern of these proteins in two distinct types of glial neoplasms, to investigate their possible correlation and probe their impact on prognosis. ERbeta, BAG-1 and HSP70 protein expression was monitored immunohistochemically in 66 cases of astrocytomas and 20 oligodendrogliomas. In astrocytic tumours low ERbeta expression correlated significantly with high grade (P < 0.001), higher expression of cytoplasmic BAG-1 (P < 0.001) and worse survival (log rank P = 0.02). Multivariate analysis revealed that ERbeta expression had a prognostic value for overall survival in these patients (Cox P = 0.03), which was not dependent on grade. There was also statistically significant association of BAG-1 nuclear expression with HSP70 cytoplasmic expression. Our results strengthen the hypothesis that ERbeta, BAG-1 and HSP70 play an important role in the pathogenesis and progression of glial neoplasms. Moreover, ERbeta expression in astrocytic tumors might be an important prognostic factor for survival.

Expression of Bag-1 and Bcl-2 and its significance in gastric cancer

AIM: To investigate the expression of Bag-1 and Bcl-2 protein and its clinical significance in gastric cancer (GC).

METHODS: Immunohistochemistry was used to detect the expressison of Bag-1 and Bcl-2 protein in 92 patients with gastric cancer and 40 normal tissues as control.

RESULTS: Compared with normal mucosa, Bag-1 and Bcl-2 were over-expressed in gastric cancerous tissues (60.9% vs 7.5%, 72.8% vs 10%, P<0.01). The expression of Bcl-2 protein was significantly correlated with the differentiation degree (r_s = 0.513, P<0.05) and the expression of Bag-1 was significantly associated with Bcl-2 level in gastric cancer (r_s = 0.522, P<0.01).

CONCLUSION: The over-expression of Bcl-2 leads to uncontrolled growth and unceasingly increases of GC cells by accelerating cell transformation and proliferation. Bag-1 promotes the function of Bcl-2 and co-expression of Bag-1 and Bcl-2 may mean poor prognosis of GC patients.

BAG-1: a multi-functional pro-survival molecule

BAG-1 is a multi-functional protein that exists as three functionally distinct and differentially localized isoforms which originate from a single mRNA and interact with a wide range of cellular targets. These include heat shock proteins, nuclear hormone receptors, signalling molecules, the anti-apoptotic BCL-2 protein and components of the ubiquitylation/proteasome machinery. Overexpression of BAG-1 isoforms has been demonstrated to regulate apoptosis, proliferation, transcription, metastasis and cell motility in a wide variety of cell systems. Since BAG-1 has a role in many biological pathways there is increasing evidence supporting the view that BAG-1 is an important molecule in disease, for example, potentially modulating both cell survival and response to nuclear hormones in breast cancer, and BAG-1 is a potential molecular target for therapeutic intervention.

BAG-1 p29 protein prevents drug-induced cell death in the presence of EGF and enhances resistance to anoikis in SKOV3 human ovarian cancer cells

BAG-1 is a multi-functional protein that exists in three major isoforms, BAG-1 p50, p46, and p36. A fourth isoform of 29 kDa also exists but its function remains mostly unknown. To further understand the role of this smaller isoform in ovarian cancer cells, the SKOV3 cell line was transfected with a doxycycline-inducible human BAG-1 p29 isoform or control plasmid. Ovexpression of BAG-1 p29 promotes protection from apoptosis in the presence of EGF as shown by decreased cell death measured by XTT assay and caspase-3 activity. Unexpectedly, however, BAG-1 p29 does not associate with the EGF receptor. When BAG-1 p29 transfectants were incubated in hydrogel-coated plates, BAG-1 p29-expressing SKOV3 cells were significantly more resistant to anoikis as compared to controls, and this correlated with decreased activation of caspase-3. The results of this study implicate BAG-1 p29 in the regulation of both the EGF signaling cascade and the apoptotic cascade induced by loss of anchorage.

Nuclear localization of KLF4 is associated with an aggressive phenotype in early-stage breast cancer

PURPOSE

The Krüppel-like transcription factor KLF4/GKLF induces both malignant transformation and a slow-growth phenotype in vitro. Although KLF4 expression is increased in most cases of breast cancer, it was unknown whether these cases represent a distinct subtype with a different clinical outcome.

EXPERIMENTAL DESIGN

We examined expression of KLF4 by immunostaining 146 cases of human primary infiltrating ductal carcinoma of the breast. Staining patterns were correlated with clinical outcome and with established prognostic factors.

RESULTS

Subcellular localization exhibited case-to-case variation. Tumors with high nuclear staining and low cytoplasmic staining were termed type 1. For patients with early-stage disease (i.e., stage I or IIA), type 1 staining was associated with eventual death because of breast cancer (hazard ratio, 2.8; 95% confidence interval, 1.23-6.58; P = 0.011). The association was stronger in patients with early-stage cancer and small primary tumors (i.e., < or =2.0 cm in diameter; hazard ratio, 4.3; 95% confidence interval, 1.75-10.62; P < 0.001). For patients with early-stage disease, multivariate analysis indicated that type 1 staining was independently associated with outcome (adjusted hazard ratio 2.6; 95% confidence interval, 1.10-6.05; P = 0.029). Type 1 staining was also associated with high histological grade (P = 0.032), increased expression of Ki67 (P = 0.016), and reduced expression of BCL2 (P = 0.032). In vitro, KLF4 was localized within the nucleus of transformed RK3E epithelial cells, consistent with a nuclear function of this transcription factor during induction of malignant transformation.

CONCLUSIONS

The results suggest that localization of KLF4 in the nucleus of breast cancer cells is a prognostic factor and identify KLF4 as a marker of an aggressive phenotype in early-stage infiltrating ductal carcinoma.

BAG-1 expression in normal and neoplastic endometrium

OBJECTIVE

BAG-1 has anti-apoptotic actions and is known to bind BCL-2 and steroid receptors. High levels of BAG-1 have been implicated as a prognostic indicator in breast cancer. Whether this observation can be generalized to endometrial cancer remains unknown.

METHODS

IRB permission was obtained for use of human discarded tissue. Immunohistochemical analyses were performed on: proliferative endometrium (PEM, 6), secretory endometrium (SEM, 28), "low-grade" neoplastic lesions (complex atypical hyperplasia and grade 1 endometrial adenocarcinomas) (19), and "high-grade" cancers (grade 2 and 3 endometrial adenocarcinomas) (13). The level of total BAG-1 and its isoforms was evaluated by Western blot in lysates from Ishikawa cells (grade 1), MFE 296 cells (grade 2), and SK-UT(2) cells (grade 3).

RESULTS

The proportion of "high-grade" cancers with positive cytoplasmic staining for BAG-1 was higher than that of secretory endometrium (P = 0.006). Additionally, the proportion of specimens with positive staining for nuclear BAG-1 expression was significantly higher among high-grade carcinoma specimens compared to secretory specimens (P = 0.009). A high proportion (91%) of all specimens were positive for BCL-2, limiting the ability to subcategorize the other variables analyzed. There was no relationship between positive nuclear BAG-1 expression and either estrogen receptor (ER) or progesterone receptor (PR) expression. BAG-1 was expressed in the three cell lines evaluated and total BAG-1 level was not different among the different cell lines.

CONCLUSION

BAG-1 is expressed in the endometrium. High-grade cancers stain more frequently than secretory endometrium for both cytoplasmic and nuclear BAG-1 expression, perhaps indicating an association between expression of BAG-1 and prognosis.

BAG-1 Expression Correlates with Bcl-2, p53, Differentiation, Estrogen and Progesterone Receptors in Invasive Breast Carcinoma

BAG-1, a recently identified anti-apoptotic protein, is overexpressed in the majority of invasive breast carcinomas. Overexpression of BAG-1 is important for both multi-step oncogenesis and resistance of cancer cells to apoptosis induced by DNA-damaging alkylating agents. BAG-1 protein species are localized differentially; nuclear expression may be associated with a shorter disease-free and overall survival in early stage breast cancer, while cytoplasmic expression has been associated with longer survival in non-small cell lung cancer. Growing evidence suggests that Bcl-2 and p53 are also involved in the oncogenesis of breast cancer. Since BAG-1 interacts with Bcl-2 and is upregulated by mutant p53 in vitro, it would be interesting to determine if their expressions are correlated with each other and with other clinical prognostic factors in invasive breast cancer. To address this question we conducted a large scale retrospective study of BAG-1, Bcl-2 and p53 in 185 breast cancer patients. Our study again showed that BAG-1 is overexpressed in the majority of breast cancer patients. In addition, it demonstrated that the expression of BAG-1 correlates with that of Bcl-2, p53, differentiation, estrogen and progesterone receptors. Our clinical study supports the preclinical finding of the interaction between BAG-1 and Bcl-2, p53 and estrogen and progesterone receptors. Further experiments to explore the prognostic and therapeutic role of BAG-1 in breast cancer are warranted.