High expression of RelA/p65 is associated with activation of nuclear factor-kappaB-dependent signaling in pancreatic cancer and marks a patient population with poor prognosis

Rationale for possible targeting of histone deacetylase signaling in cancer diseases with a special reference to pancreatic cancer

There is ongoing interest to identify signaling pathways and genes that play a key role in carcinogenesis and the development of resistance to antitumoral drugs. Given that histone deacetylases (HDACs) interact with various partners through complex molecular mechanims leading to the control of gene expression, they have captured the attention of a large number of researchers. As a family of transcriptional corepressors, they have emerged as important regulators of cell differentiation, cell cycle progression, and apoptosis. Several HDAC inhibitors (HDACis) have been shown to efficiently protect against the growth of tumor cells in vitro as well as in vivo. The pancreatic cancer which represents one of the most aggressive cancer still suffers from inefficient therapy. Recent data, although using in vitro tumor cell cultures and in vivo chimeric mouse model, have shown that some of the HDACi do express antipancreatic tumor activity. This provides hope that some of the HDACi could be potential efficient anti-pancreatic cancer drugs. The purpose of this review is to analyze some of the current data of HDACi as possible targets of drug development and to provide some insight into the current problems with pancreatic cancer and points of interest for further study of HDACi as potential molecules for pancreatic cancer adjuvant therapy.

Metastasis-associated protein 1 nuclear expression is associated with tumor progression and clinical outcome in patients with non-small cell lung cancer

INTRODUCTION

Little research has been done to test the usefulness of metastasis-associated protein 1 (MTA1) as a prognostic marker for non-small cell lung cancer (NSCLC). In this study, we investigated MTA1 expression and its prognostic value for NSCLC.

METHODS

NSCLC surgical tissue samples were taken from 100 patients with NSCLC who had been followed up for more than 2 years. The expression of MTA1 protein was evaluated by immunohistochemistry, and the correlations between the expression of MTA1 and clinical features and the prognosis were analyzed. The difference of MTA1 protein expression between NSCLCs and their adjacent nonneoplastic lung tissues was analyzed in a tissue microarray. The change of MTA1 mRNA expression and protein expression after RNA interference (RNAi) was detected by real-time polymerase chain reaction, Western blot, and immunocytochemistry in NSCLC cell line 95D.

RESULTS

Overexpression of MTA1 (immunoreactivity scoring >4) was shown in 61.0% of the NSCLC cases but only in 9.4% of their adjacent nonneoplastic lung tissues (p < 0.001). The MTA1 expression level was correlated with lymph node metastasis (p = 0.013) and clinical stage (p = 0.002). Survival analysis showed that the MTA1 overexpression group had a significantly shorter overall survival time than the MTA1 downexpression group (p = 0.003). However, multivariate analysis showed that MTA1 expression was not a significant and independent prognostic parameter for patients with NSCLC. After RNAi, the 95D cells exhibit consistent reduction in MTA1 mRNA expression and MTA1 protein expression.

CONCLUSION

MTA1 protein expression is associated with tumor progression and clinical outcome in patients with NSCLC. Further molecular, cellular, and animal model studies on MTA1 gene will provide new clues for exploring the mechanism of carcinogenesis and tumor progression in patients with NSCLC.

Nuclear factor-κB expression is predictive of overall survival in patients with cutaneous melanoma

Nuclear factor (NF)- κB is one of the most important transcription factors that plays a crucial role in the regulation of a wide spectrum of genes involved in modulating the cell cycle, apoptosis, cell growth, angiogenesis, inflammation and the tissue invasiveness of highly malignant cells. NF-κB activity has been found to be constitutively elevated in a number of human tumors from either a haematological or solid origin, such as melanomas. In several studies, NF-κB activation was shown to be an adverse prognostic factor, and in melanoma it was proposed as an event that promotes tumor progression. This study aimed to evaluate whether NF-κB activation in tumor tissues, assessed by the expression of the NF-κB p65 subunit, has an effect on the survival of melanoma patients. The expression of NF-κB was immunohistochemically investigated, and the correlation with survival was analyzed. Furthermore, the immunostaining for p53 and survivin was evaluated, and the relationship of these apoptotic and anti-apoptotic factors with NF-κB expression was analyzed. Kaplan-Meier analysis showed that patients with low levels of NF-κB in the nuclei of tumor cells had a significantly longer survival compared to those with high levels. Multivariate analysis confirmed the predictive value of nuclear NF-κB, showing that its expression maintains significance after the model was adjusted using clinicopathological factors. The results demonstrate the correlation of NF-κB p65 nuclear staining with the disease-specific 5-year survival of melanoma patients and suggest that nuclear NF-κB p65 may be promising as an early independent prognostic factor in patients with primary cutaneous melanoma.

Resveratrol, a multitargeted agent, can enhance antitumor activity of gemcitabine in vitro and in orthotopic mouse model of human pancreatic cancer

Gemcitabine, while a standard treatment of advanced pancreatic cancer (PaCa), alone is not very effective. New agents that are safe and effective are highly needed. Resveratrol is one such agent which is safe and multitargeted; and has been linked with suppression of survival, proliferation, invasion and angiogenesis of cancer. Whether resveratrol can sensitize PaCa to gemcitabine in vitro and in vivo was investigated. We established PaCa xenografts in nude mice, randomized into 4 groups, and treated with vehicle, gemcitabine, resveratrol and with combination. Modulation of NF-kappaB and markers of proliferation, angiogenesis and invasion were ascertained using electrophoretic mobility shift assay (EMSA), immunohistochemistry and western blot analysis. Resveratrol inhibited the proliferation of 4 different human PaCa cell lines, synergized the apoptotic effects of gemcitabine, inhibited the constitutive activation of NF-kappaB and expression of bcl-2, bcl-xL, COX-2, cyclin D1 MMP-9 and VEGF. In an orthotopic model of human PaCa, we found that resveratrol significantly suppressed the growth of the tumor (p < 0.001) and this effect was further enhanced by gemcitabine (p < 0.001). Both the markers of proliferation index Ki-67 and the micro vessel density CD31 were significantly downregulated in tumor tissue by the combination of gemcitabine and resveratrol (p < 0.001 vs. control; p < 0.01 vs. gemcitabine). As compared to vehicle control, resveratrol also suppressed the NF-kappaB activation and expression of cyclin D1, COX-2, ICAM-1, MMP-9 and survivin. Overall our results demonstrate that resveratrol can potentiate the effects of gemcitabine through suppression of markers of proliferation, invasion, angiogenesis and metastasis.

Expression of classical NF-kappaB pathway effectors in human ovarian carcinoma

AIMS

Functional studies have demonstrated that nuclear factor (NF)-kappaB promotes tumour progression in ovarian cancer cells. However, surprisingly little is known of the expression of effectors of the NF-kappaB pathway in human ovarian cancer in vivo.

METHODS AND RESULTS

Immunohistochemistry and in situ hybridization revealed that in a cohort of 85 primary ovarian carcinomas, total p65 expression was inversely correlated to nuclear and cytoplasmic phospho-IkappaBalpha (P = 0.002 and P = 0.05, respectively), and IkappaBalpha mRNA expression (P = 0.032). In contrast, phospho-p65 expression was paralleled by the expression of nuclear (P = 0.027) and cytoplasmic phospho-IkappaBalpha (P = 0.01). Total p65 expression was an adverse prognostic factor for overall survival (P = 0.018). In contrast, total IkappaBalpha and phosphorylated nuclear and cytoplasmic IkappaBalpha expression were favourable prognostic markers (P = 0.001, P = 0.031, P = 0.001, respectively). Cytoplasmic phospho-IkappaBalpha expression remained a significant prognostic factor on multivariate analysis (P = 0.010). In cultured, stimulated OVCAR-3 ovarian cancer cells the cytoplasmic retranslocation of p65 was delayed by inhibition of the nuclear membrane transporter chromosomal region maintenance/exportin1 protein (CRM1). A positive association of p65 and CRM1 expression was demonstrated in ovarian cancer tissue (P < 0.0001).

CONCLUSIONS

Total and phosphorylated IkappaBalpha protein expression might serve as markers for NF-kappaB activation in human ovarian carcinoma. Cytoplasmic localization of p65 may be related to deregulated nucleocytoplasmic transport in carcinomas overexpressing CRM1.

Expression of nuclear transcription factor kappa B in locally advanced human cervical cancer treated with definitive chemoradiation

PURPOSE

Nuclear factor kappa B (NF-κB), a transcriptional factor that has been shown to be constitutively active in cervical cancer, is part of an important pathway leading to treatment resistance in many tumor types. The purpose of our study was to determine whether expression of NF-κB in pretreatment specimens and specimens taken shortly after treatment initiation correlated with outcome in cervical cancer patients treated with definitive chemoradiation.

METHODS AND MATERIALS

Eighteen patients with locally advanced cervical cancer were enrolled in a study in which cervical biopsy specimens were obtained before radiation therapy and 48 h after treatment initiation. Matched biopsy specimens from 16 of these patients were available and evaluated for the nuclear expression of NF-κB protein by immunohistochemical staining.

RESULTS

After a median follow-up of 43 months, there were 9 total treatment failures. Nuclear staining for NF-κB was positive in 3 of 16 pretreatment biopsy specimens (19%) and 5 of 16 postradiation biopsy specimens (31%). Pretreatment expression of NF-κB nuclear staining correlated with increased rates of local-regional failure (100% vs. 23%, p = 0.01), distant failure (100% vs. 38%, p = 0.055), disease-specific mortality (100% vs. 31%, p = 0.03), and overall mortality (100% vs. 38%, p = 0.055).

CONCLUSIONS

Our data suggest that pretreatment nuclear expression of NF-κB may be associated with a poor outcome for cervical cancer patients treated with chemoradiation. Although these data require validation in a larger group of patients, the results support the continued study of the relationship between NF-κB and outcome in patients treated for carcinoma of the cervix.

High class I HDAC activity and expression are associated with RelA/p65 activation in pancreatic cancer in vitro and in vivo

Background

The strong association between aberrant HDAC activity and the occurrence of cancer has led to the development of a variety of HDAC inhibitors (HDIs), which emerge as promising new targeted anticancer therapeutics.

Methods

Due to the pivotal role of RelA/p65 in the tumorigenesis of pancreatic neoplasia we examined the expression of class I HDACs 1, 2 and 3 in a large cohort of human pancreatic carcinomas and correlated our findings with RelA/p65 expression status. Furthermore, we investigated the impact of the HDIs SAHA and VPA on RelA/p65 activity in pancreatic cancer cell culture models.

Results

Class I HDACs were strongly expressed in a subset of pancreatic adenocarcinomas and high expression was significantly correlated with increased nuclear translocation of RelA/p65 (p = 0.024). The link of HDAC activity and RelA/p65 in this tumor entity was confirmed in vitro, where RelA/p65 nuclear translocation as well as RelA/p65 DNA binding activity could be markedly diminished by HDI treatment.

Conclusion

The RelA/p65 inhibitory effects of SAHA and VPA in vitro and the close relationship of class I HDACs and RelA/p65 in vivo suggest that treatment with HDIs could serve as a promising approach to suppress NF-κB activity which in turn may lead to enhanced apoptosis and chemosensitization of pancreatic cancers.

Chronic pancreatitis and pancreatic cancer: prediction and mechanism

We investigated the SPINK 1 mutations in 156 sporadic pancreatic cancer (PCa), and 8 pancreatic cancer with chronic pancreatitis (CPPCa) patients, and in 527 healthy subjects. The results demonstrated that 3 of 8 patients with CPPCa (37.5%) had the SPINK 1 gene N34S mutation. In addition, 3 of 156 sporadic PCa patients (1.9%) and 1 of them (0.6%) had the N34S and IVS3+2T>C mutation, respectively. The combined frequency of 2.5% was significantly higher than that of healthy subjects (0.38%), suggesting that the SPINK 1 mutation is an important risk factor for the development of pancreatic cancer. To investigate the genetic difference between sporadic PCa and CPPCa, we investigated several factors involved in the pathogenesis of PCa in 6 CPPCa and 15 sporadic PCa patients. The factors examined were genes including K-ras, p53, smad 4, p-smad 1, CXCL 14, NF-kB subunit p65 and Wnt 5a. No significant difference was found in the comparative examination of these factors, suggesting that the molecular disorders appeared to occur similarly in CPPCa as well as sporadic PCa. To assess the role of fibrosis in pancreatic carcinogenesis, we investigated the effects of pancreatic stellate cells (PSCs), which are largely responsible for pancreatic fibrogenesis, on duct cells, in vitro and in vivo. Activated PSCs were found surrounding precancerous duct cells in the tissues of a dimethylbenzanthracene mouse model and those of human PCa. Consistently, human pancreatic epithelial duct cells cultured with PSC conditioned media showed increased cell proliferation and colony formation, suggesting that PSCs may promote pancreatic ductal tumorigenesis.

Consensus on the treatment of pancreatic cancer in Spain

Pancreatic cancer (PC) represents one of the greatest oncological challenges of our century, due to its high mortality and incidence. A group of Spanish experts in PC treatment reviewed data available on different therapeutic combinations and established consensus on what would be the best strategy in PC management, depending on the stage of the disease. Surgery with complete resection may produce 5-year survival rates of 18-24%, but definitive control is still precarious. In the absence of consensus, the best evidence suggests that adjuvant chemotherapy with gemcitabine for 6 months using the CONKO-001 regime is the treatment of choice after resection of PC for patients with acceptable functional status. This group recommends chemoradiotherapy (CT-RT) in patients with factors for poor loco-regional prognosis. However, chemotherapy is an option for the treatment of locally advanced PC in patients with good general status and in the absence of metastatic disease the recommended treatment is CT-RT followed by gemcitabine-based chemotherapy. A period of chemotherapy followed by consolidation CT-RT may be appropriate, as it allows selection of patients with locally advanced disease who may benefit most from combined treatment. Erlotinib combined with gemcitabine shows significant survival improvement in PC and must be considered an option in the first-line treatment of advanced and metastatic PC. The gemcitabine-erlotinib combination is proposed as the standard treatment for metastatic PC in patients with PS=/>2. In patients with PS<2, gemcitabine-erlotinib is recommended as the first-line treatment option, supported by a maximum degree of evidence, without ruling out other options, such as gemcitabine-oxaliplatin, gemcitabine-capecitabine or gemcitabine alone.

Inflammation and cancer: how friendly is the relationship for cancer patients?

Evidence has emerged in the last two decades that at the molecular level most chronic diseases, including cancer, are caused by a dysregulated inflammatory response. The identification of transcription factors such as NF-kappaB, AP-1 and STAT3 and their gene products such as tumor necrosis factor, interleukin-1, interleukin-6, chemokines, cyclooxygenase-2, 5 lipooxygenase, matrix metalloproteases, and vascular endothelial growth factor, adhesion molecules and others have provided the molecular basis for the role of inflammation in cancer. These inflammatory pathways are activated by tobacco, stress, dietary agents, obesity, alcohol, infectious agents, irradiation, and environmental stimuli, which together account for as much as 95% of all cancers. These pathways have been implicated in transformation, survival, proliferation, invasion, angiogenesis, metastasis, chemoresistance, and radioresistance of cancer, so much so that survival and proliferation of most types of cancer stem cells themselves appear to be dependent on the activation of these inflammatory pathways. Most of this evidence, however, is from preclinical studies. Whether these pathways have any role in prevention, progression, diagnosis, prognosis, recurrence or treatment of cancer in patients, is the topic of discussion of this review. We present evidence that inhibitors of inflammatory biomarkers may have a role in both prevention and treatment of cancer.

Increases in nuclear p65 activation in dystrophic skeletal muscle are secondary to increases in the cellular expression of p65 and are not solely produced by increases in IkappaB-alpha kinase activity

Dystrophin-deficient muscle exhibits substantial increases in nuclear NF-kappaB activation. To examine potential mechanisms for this enhanced activation, the present study employs conventional Western blot techniques to provide the first determination of the relative expression of NF-kappaB signaling molecules in adult nondystrophic and dystrophic (mdx) skeletal muscle. The results indicate that dystrophic muscle is characterized by increases in the whole cell expression of IkappaB-alpha, p65, p50, RelB, p100, p52, IKK, and TRAF-3. The proportion of phosphorylated IkappaB-alpha, p65, NIK, and IKKbeta, and the level of cytosolic IkappaB-alpha, were also increased in the mdx diaphragm. Proteasomal inhibition using MG-132 increased the proportion of phosphorylated IkappaB-alpha in nondystrophic diaphragm, but did not significantly increase this proportion in the mdx diaphragm. This result suggests that phosphorylated IkappaB-alpha accumulates in dystrophic cytosol because the rate of IkappaB-alpha degradation is lower than the effective rate of IkappaB-alpha synthesis and phosphorylation. Dystrophic increases in SUMO-1 (small ubiquitin modifier-1) protein and in Akt activation were also observed. The results indicate that increases in nuclear p65 activation in dystrophic muscle are not produced solely by increases in the activity of IkappaB-alpha kinase (IKK), but are due primarily to increases in the expression of p65 and other NF-kappaB signaling components.

NF-kappaB activation through the alternative pathway correlates with chemoresistance and poor survival in extranodal NK/T-cell lymphoma, nasal type

OBJECTIVE

Nuclear factor-kappaB (NF-kappaB) activation has been identified in a variety of solid tumors and lymphoid malignancies. The aim of our study was to determine the expression status and clinical significance of NF-kappaB in extranodal natural killer (NK)/T-cell lymphoma, nasal type.

METHODS

Tumor specimens from 23 patients with previously untreated NK/T-cell lymphoma initially treated with cyclophosphamide, vincristine, doxorubicin and prednisone (CHOP) or CHOP-based chemotherapy were examined by immunohistochemistry for three NF-kappaB subunits (p65, p50 and p52), which are involved in either the canonical or alternative pathway.

RESULTS

None of the cases could be detected with p65 or p50 nuclear staining. On the other hand, 15 (65.2%) cases had p52 nuclear staining, suggesting NF-kappaB activation through the alternative pathway. All major clinical characteristics were balanced between NF-kappaB p52-positive and -negative patients. The objective response rate achieved in NF-kappaB-positive patients was significantly lower than that in negative patients (33.3% vs. 87.5%, P = 0.027). At a median follow-up of 25 months, 8 (53.3%) of 15 NF-kappaB-positive patients had died compared with none of 8 NF-kappaB-negative patients (P = 0.041). In a multivariate analysis, NF-kappaB status and stage were identified to be independent prognostic factors.

CONCLUSIONS

Our results suggest that NF-kappaB activation through the alternative pathway is frequently observed in NK/T-cell lymphoma and associated with chemoresistance and poor survival.

Cleaved caspase-3 and nuclear factor-kappaB p65 are prognostic factors in metastatic serous ovarian carcinoma

Tumor progression and treatment failure in ovarian carcinoma are frequently associated with metastasis to effusions. The present study analyzed the expression and clinical role of nuclear factor-kappaB p65, nuclear factor-kappaB inhibitor alpha, and parameters of apoptosis in serous carcinoma. Cleaved caspase-3 and caspase-8 levels and deoxyuridine triphosphate incorporation were measured in 65 effusions using flow cytometry. Effusions (n = 209) and corresponding primary carcinomas and solid metastases (n = 114) were immunohistochemically analyzed for nuclear factor-kappaB p65 and nuclear factor-kappaB inhibitor alpha expression. Effusions (n = 75) were further analyzed for nuclear factor-kappaB phospho-p65 (Ser536) levels using immunoblotting. Results were analyzed for association with anatomic site, clinicopathologic parameters, and survival. Caspase cleavage and deoxyuridine triphosphate incorporation were limited to less than 10% of cells in most effusions. Nuclear factor-kappaB p65 expression was frequently detected at all anatomic sites, with less frequent cytoplasmic nuclear factor-kappaB p65 and nuclear factor-kappaB inhibitor alpha expressions. Immunoblotting showed nuclear factor-kappaB p65 phosphorylation in 72 (96%) of 75 effusions. Higher than median cleaved caspase-3 levels correlated with improved overall and progression-free survival in univariate analysis of all patients (P = .024 and P = .046, respectively) and of those with postchemotherapy effusions (P = .042 and P = .036, respectively). Cleaved caspase-3 expression was an independent predictor of longer progression-free survival for patients with postchemotherapy effusions (P = .029). Nuclear factor-kappaB p65 expression correlated with poor progression-free survival for all patients (P = .048) and for those with postchemotherapy effusions (P = .025). Ovarian carcinoma cells in effusions undergo little apoptosis, but high levels of cleaved caspase-3 are associated with improved survival. Nuclear factor-kappaB p65 is frequently expressed in advanced-stage serous ovarian carcinoma, and its nuclear localization is associated with poor progression-free survival.

Nuclear factor-kappaB p65/relA silencing induces apoptosis and increases gemcitabine effectiveness in a subset of pancreatic cancer cells

PURPOSE

Nuclear factor kappaB (NFkappaB) activity may increase survival and protect cancer cells from chemotherapy. Therefore, NFkappaB activity may be prognostic, and inhibition of NFkappaB may be useful for pancreatic cancer therapy. To test these hypotheses, we examined NFkappaB activity and the effects of inhibiting NFkappaB in several pancreatic cancer cell lines with differing sensitivities to gemcitabine.

EXPERIMENTAL DESIGN

The gemcitabine sensitivity of pancreatic cancer cell lines BxPC-3, L3.6pl, CFPAC-1, MPanc-96, PANC-1, and MIA PaCa-2 were determined by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide and fluorescence-activated cell sorting assays. NFkappaB levels were determined by electrophoretic mobility shift assay and reporter assays. The effects of gemcitabine on NFkappaB activity were determined in vitro and in vivo. NFkappaB was inhibited by silencing of the p65/relA subunit using small interfering RNA in vitro and by neutral liposomal delivery of small interfering RNA in vivo, and the effects were evaluated on gemcitabine sensitivity.

RESULTS

The cell lines L3.6pl, BxPC-3, and CFPAC-1 were sensitive, whereas MPanc-96, PANC-1, and MIA PaCa-2 were resistant to gemcitabine. No significant correlation was observed between basal NFkappaB activity and gemcitabine sensitivity. Gemcitabine treatment did not activate NFkappaB either in vitro or in vivo. Silencing of p65/relA induced apoptosis and increased gemcitabine killing of all gemcitabine-sensitive pancreatic cancer cells. No significant effects, however, were observed on gemcitabine-resistant pancreatic cancer cell lines either in vitro or in vivo.

CONCLUSIONS

NFkappaB activity did not correlate with sensitivity to gemcitabine. Silencing of p65/relA was effective alone and in combination with gemcitabine in gemcitabine-sensitive but not gemcitabine-resistant pancreatic cancer cells. Thus, NFkappaB may be a useful therapeutic target for a subset of pancreatic cancers.

Apoptotic pathways in pancreatic ductal adenocarcinoma

Pancreatic ductal adenocarcinoma (PDAC) is one of the most common causes of cancer related death. Despite the advances in understanding of the molecular pathogenesis, pancreatic cancer remains a major unsolved health problem. Overall, the 5-year survival rate is less than 5% demonstrating the insufficiency of current therapies. Most cytotoxic therapies induce apoptosis and PDAC cells have evolved a plethora of molecular mechanisms to assure survival. We will present anti-apoptotic strategies working at the level of the death receptors, the mitochondria or involving the caspase inhibitors of the IAP family. Furthermore, the survival function of the phosphotidylinositol-3' kinase (PI3K)/AKT- and NF-kappaB-pathways are illustrated. A detailed molecular knowledge of the anti-apoptotic mechanisms of PDAC cells will help to improve therapies for this dismal disease and therapeutic strategies targeting the programmed cell death machinery are in early preclinical and clinical development.

NF-kappaB and cancer-identifying targets and mechanisms

A connection between inflammation and carcinogenesis has long been known, but the precise mechanisms are just beginning to be understood. NF-kappaB proteins, transcription factors which integrate stress signals and orchestrate immune responses, have also recently been linked to carcinogenesis. Hallmarks of cancer development include self-sufficiency in growth signals, insensitivity to growth-inhibitors, evasion of apoptosis, limitless replicative potential, tissue invasion and metastasis, and sustained angiogenesis. NF-kappaB signaling has been implicated in each of these hallmarks, and recent experimental studies have illuminated the mechanistic pathways by which NF-kappaB signaling contributes to these aspects of carcinogenesis. This review will focus on recent experimental data supporting the hypothesis that inflammation promotes carcinogenesis, and that NF-kappaB signaling is at the heart of such inflammation.

Association of patterns of class I histone deacetylase expression with patient prognosis in gastric cancer: a retrospective analysis

BACKGROUND

Although histone deacetylases (HDACs) are known to have an important regulatory role in cancer cells, and HDAC inhibitors (HDIs) have entered late-phase clinical trials for the treatment of several cancers, little is known about the expression patterns of HDAC isoforms in tumours. We aimed to clarify these expression patterns and identify potential diagnostic and prognostic uses of selected class I HDAC isoforms in gastric cancer.

METHODS

Tissue samples from a training cohort and a validation cohort of patients with gastric cancer from two German institutions were used for analyses. Tissue microarrays were generated from tumour tissue collected from patients in the training group, whereas tissue slides were used in the validation group. The tissues were scored for expression of class I HDAC isoforms 1, 2, and 3. Overall expression patterns (gHDAC) were grouped as being negative (all three isoforms negative), partially positive (one or two isoforms positive), or completely positive (all isoforms positive), and correlated with clinicopathological parameters and patient survival. The main endpoints were amount of expression of each of the three HDAC isoforms, patterns of expression of gHDAC, effect of metastasis on expression of HDAC and gHDAC, and overall survival according to HDAC expression patterns.

FINDINGS

2617 tissue microarray spots from 143 patients in the training cohort and 606 tissue slides from 150 patients in the validation cohort were studied. 52 of the 143 (36%) gastric tumours in the training cohort and 32 of the 150 (21%) gastric tumours in the validation cohort showed nuclear expression of all three HDAC isoforms. 60 (42%) of tumours in the training cohort and 65 (43%) in the validation cohort expressed one or two isoforms in the nuclei, whereas 31 (22%) of tumours in the training cohort and 53 (35%) in the validation cohort were scored negative for all three proteins. gHDAC expression in both cohorts was higher when lymph-node metastases were present (p=0.0175 for the training group and p=0.0242 for the validation group). Survival data were available for 49 patients in the training group and 123 patients in the validation group. In the validation cohort, 3-year survival was 44% (95% CI 34-57) in the HDAC1-negative group, 50% (39-64) in the HDAC2-negative group, and 48% (34-67) in the gHDAC-negative group. 3-year survival decreased to 21% (11-37) when HDAC1 was positive, 16% (9-31) when HDAC2 was positive, and 5% (1-31) when gHDAC (all isoforms) were positive. Those patients highly expressing one or two isoforms (the gHDAC-intermediate group) had an estimated 3-year survival of 40% (29-56). In multivariate analyses, high gHDAC and HDAC2 expression were associated with shorter survival in the training cohort (gHDAC: hazard ratio [HR] 4.15 [1.23-13.99], p=0.0250; HDAC2: HR 3.58 [1.36-9.44], p=0.0100) and in the validation cohort (gHDAC: HR 2.18 [1.19-4.01], p=0.0433; HDAC2: HR 1.72 [1.08-2.73], p=0.0225), independent of standard clinical predictors.

INTERPRETATION

High HDAC expression is significantly associated with nodal spread and is an independent prognostic marker for gastric cancer. Additionally, we postulate that immunohistochemical detection of HDAC as a companion diagnostic method might predict treatment response to HDIs, thereby enabling selection of patients for this specific targeted treatment in gastric cancer.