Distant Prostate Cancer Metastases Research Articles

Gut dysbiosis promotes prostate cancer progression and docetaxel resistance via activating NF-κB-IL6-STAT3 axis

BackgroundThe gut microbiota is reportedly involved in the progression and chemoresistance of various human malignancies. However, the underlying mechanisms behind how it exerts some effect on prostate cancer, as an extra-intestinal tumor, in a contact-independent way remain elusive and deserve exploration. Antibiotic exposure, one of the various factors affecting the gut microbiota community and capable of causing gut dysbiosis, is associated with multiple disorders. This study aims to preliminarily clarify the link between gut dysbiosis and prostate cancer.ResultsFirst, we discovered that perturbing the gut microbiota by consuming broad-spectrum antibiotics in water promoted the growth of subcutaneous and orthotopic tumors in mice. Fecal microbiota transplantation could transmit the effect of antibiotic exposure on tumor growth. Then, 16S rRNA sequencing for mouse feces indicated that the relative abundance of Proteobacteria was significantly higher after antibiotic exposure. Meanwhile, intratumoral lipopolysaccharide (LPS) profoundly increased under the elevation of gut permeability. Both in vivo and in vitro experiments revealed that the NF-κB-IL6-STAT3 axis activated by intratumoral LPS facilitated prostate cancer proliferation and docetaxel chemoresistance. Finally, 16S rRNA sequencing of patients’ fecal samples revealed that Proteobacteria was enriched in patients with metastatic prostate cancer and was positively correlated with plasma IL6 level, regional lymph node metastasis status, and distant metastasis status. The receiver operating characteristic (ROC) curves showed that the relative abundance of Proteobacteria had better performance than the prostate-specific antigen (PSA) level in predicting the probability of distant metastasis in prostate cancer (area under the ROC curve, 0.860; p < 0.001).ConclusionCollectively, this research demonstrated that gut dysbiosis, characterized by the enrichment of Proteobacteria due to antibiotic exposure, resulted in the elevation of gut permeability and intratumoral LPS, promoting the development of prostate cancer via the NF-κB-IL6-STAT3 axis in mice. Considering findings from human patients, Proteobacteria might act as an intestinal biomarker for progressive prostate cancer.8Rvk2m_7VYdxXtFw33rTopVideo

Definitive and sustained increase in prostate cancer metastases in the United States

IntroductionWe examined the most recent Surveillance, Epidemiology, and End Results release to corroborate temporal trends in nonmetastatic and distant prostate cancer metastases in the United States. MethodsSurveillance, Epidemiology, and End Results was analyzed for the incidence of nonmetastatic and distant metastasis for men with prostate cancer aged 50–74 and ≥75 years during 2004–2015. Incidence ratios (IR) were calculated relative to the year prior. ResultsThe incidence of distant metastasis significantly increased from 451.0 to 504.0 per million (IR:1.12, 95% CI:1.01–1.24) from 2011 to 2012 and 532.3 to 586.1 per million (IR:1.10, 95% CI:1.00–1.21) from 2014 to 2015 in men aged ≥75 years. The incidence of distant metastasis did not significantly increase in men aged 55–74 over the study period. ConclusionWe demonstrate a sustained and definitive increase in prostate cancer distant metastases in men aged ≥75 years. Although our observational study design cannot pinpoint the exact cause of this increase, which is likely multifactorial, this shift reverses declines in metastases at diagnoses that followed the advent of prostate-specific antigen screening.

PD30-10 DEFINITIVE AND SUSTAINED INCREASE IN PROSTATE CANCER METASTASES IN THE UNITED STATES

INTRODUCTION AND OBJECTIVES:Although a significant increase in distant prostate cancer metastases at diagnosis was witnessed from 2011 to 2013 in the United States,these findings were met with just...

The Proteome of Prostate Cancer Bone Metastasis Reveals Heterogeneity with Prognostic Implications.

Purpose: Bone is the most predominant site of distant metastasis in prostate cancer, and patients have limited therapeutic options at this stage.Experimental Design: We performed a system-wide quantitative proteomic analysis of bone metastatic prostate tumors from 22 patients operated to relieve spinal cord compression. At the time of surgery, most patients had relapsed after androgen-deprivation therapy, while 5 were previously untreated. An extended cohort of prostate cancer bone metastases (n = 65) was used for immunohistochemical validation.Results: On average, 5,067 proteins were identified and quantified per tumor. Compared with primary tumors (n = 26), bone metastases were more heterogeneous and showed increased levels of proteins involved in cell-cycle progression, DNA damage response, RNA processing, and fatty acid β-oxidation; and reduced levels of proteins were related to cell adhesion and carbohydrate metabolism. Within bone metastases, we identified two phenotypic subgroups: BM1, expressing higher levels of AR canonical targets, and mitochondrial and Golgi apparatus resident proteins; and BM2, with increased expression of proliferation and DNA repair-related proteins. The two subgroups, validated by the inverse correlation between MCM3 and prostate specific antigen immunoreactivity, were related to disease prognosis, suggesting that this molecular heterogeneity should be considered when developing personalized therapies.Conclusions: This work is the first system-wide quantitative characterization of the proteome of prostate cancer bone metastases and a valuable resource for understanding the etiology of prostate cancer progression. Clin Cancer Res; 24(21); 5433-44. ©2018 AACR.

Abstract B025: The proteome of prostate cancer bone metastases

Abstract Bone is the most predominant site of distant metastasis in prostate cancer. Patients who develop bone metastases have limited therapeutic options and poor prognosis. Understanding the cellular and molecular changes occurring at this stage is critical to find new treatments and to stratify patients for personalized therapies. In the current study, we used a system-wide quantitative proteomic approach in order to identify (i) cellular alterations occurring during the transition from localized to metastasized prostate cancer and (ii) phenotypic subgroups and potential novel targets for treatment of metastatic prostate cancer. Mass spectrometry-based quantitative proteomic profiling was applied to paraffin-embedded, formalin-fixed bone metastasis tissue from prostate cancer patients (n=22) operated to relieve spinal cord compression. At the time of surgery, 5 patients were previously untreated, 16 had relapsed after androgen-deprivation therapy (ADT), and 1 was under early ADT. Mechanisms behind disease progression were identified through comparative analysis with proteomic profiles of localized prostate cancer (n=26) and adjacent normal tissue (n=8) obtained from radical prostatectomies. Expression levels of selected proteins were verified by immunohistochemical analysis of metastases from our extended bone-metastasis cohort. A mean of 5,067 proteins were identified and quantified per tumor. Compared to primary prostate tumors (1) bone metastases showed increased levels of proteins involved in cell cycle progression, DNA damage response, RNA processing, lipid transport, and fatty acid β-oxidation as well as reduced levels of proteins involved in cell adhesion and carbohydrate metabolism. Based on their proteomes, prostate cancer metastases were more heterogeneous (ρ:0.64±0.077) than localized tumors (ρ:0.8±0.037). We identified two phenotypically different subgroups of metastatic tumors: (i) those expressing higher levels of androgen receptor canonical targets together with elevated levels of mitochondrial and Golgi apparatus resident proteins and (ii) those with increased expression of proliferation and DNA repair-related proteins. Importantly, the two subgroups were seen among both treatment-naïve and castration-resistant cases and thus unrelated to previous treatment. The inverse correlation between tumor cell proliferation and metabolically/secretory active tumor cells was verified by assessment of Ki67 and PSA immunoreactivity in 78 bone metastases (Rs=-0.36, P=0.001). Identification of novel therapeutic targets/strategies for the two subgroups is ongoing. In conclusion, this work describes the first system-wide quantitative characterization of the proteome in prostate cancer bone metastases. By deep proteomic analysis we revealed the existence of at least two different subtypes of prostate cancer bone metastasis according to proliferative and metabolic features, suggesting that personalized therapies could be considered based on molecular signatures in individual cases. Reference: 1. Iglesias-Gato D, et al. The proteome of primary prostate cancer. Eur Urol 2016:69:942-52. Citation Format: Diego Iglesias-Gato, Elin Thysell, Sead Crnalic, Matthias Mann, Anders Widmark, Anders Bergh, Amilcar Flores-Morales, Pernilla Wikström. The proteome of prostate cancer bone metastases [abstract]. In: Proceedings of the AACR Special Conference: Prostate Cancer: Advances in Basic, Translational, and Clinical Research; 2017 Dec 2-5; Orlando, Florida. Philadelphia (PA): AACR; Cancer Res 2018;78(16 Suppl):Abstract nr B025.

Downregulation of miR-133a-3p promotes prostate cancer bone metastasis via activating PI3K/AKT signaling

BackgroundBone metastasis is a leading cause of morbidity and mortality in advanced prostate cancer (PCa). Downexpression of miR-133a-3p has been found to contribute to the progression, recurrence and distant metastasis in PCa. However, clinical significance of miR-133a-3p in bone metastasis of PCa, and the biological role of miR-133a-3p and its molecular mechanisms underlying bone metastasis of PCa remain unclear.MethodsmiR-133a-3p expression was evaluated in 245 clinical PCa tissues by real-time PCR. Statistical analysis was performed to evaluate the clinical correlation between miR-133a-3p expression and clinicopathological features, and overall and bone metastasis-free survival in PCa patients. The biological roles of miR-133a-3p in the bone metastasis of PCa were investigated both in vitro and in vivo. Bioinformatics analysis, real-time PCR, western blot and luciferase reporter analysis were applied to demonstrate the relationship between miR-133a-3p and its potential targets. Western blotting and luciferase assays were examined to identify the underlying pathway involved in the anti-tumor role of miR-133a-3p. Clinical correlation of miR-133a-3p with its targets was verified in human PCa tissues.ResultsmiR-133a-3p expression is reduced in PCa tissues compared with the adjacent normal tissues and benign prostate lesion tissues, particularly in bone metastatic PCa tissues. Low expression of miR-133a-3p is significantly correlated with advanced clinicopathological characteristics and shorter bone metastasis-free survival in PCa patients by statistical analysis. Moreover, upregulating miR-133a-3p inhibits cancer stem cell-like phenotypes in vitro and in vivo, as well as attenuates anoikis resistance in vitro in PCa cells. Importantly, administration of agomir-133a-3p greatly suppresses the incidence of PCa bone metastasis in vivo. Our results further demonstrate that miR-133a-3p suppresses bone metastasis of PCa via inhibiting PI3K/AKT signaling by directly targeting multiple cytokine receptors, including EGFR, FGFR1, IGF1R and MET. The negative clinical correlation of miR-133a-3p with EGFR, FGFR1, IGF1R, MET and PI3K/AKT signaling activity is determined in clinical PCa tissues.ConclusionOur results unveil a novel mechanism by which miR-133a-3p inhibits bone metastasis of PCa, providing the evidence that miR-133a-3p may serve as a potential bone metastasis marker in PCa, and delivery of agomir-133a-3p may be an effective anti-bone metastasis therapeutic strategy in PCa.

Abstract 79: Stromal regulation of prostate cancer cell proliferation by mevalonate pathway enzymes HMGCS1 and HMGCR

Abstract It has been suggested that the tumor microenvironment plays an important role in tumor progression, acquisition of androgen independence, and distant metastasis in prostate cancer (PC). However, little is known about the transcriptional basis of cellular interactions in the human PC microenvironment. To clarify the mechanism of PC progression and metastasis, we investigated the interaction of PC, epithelial, and stromal cells by analyzing genome-wide gene expression profiles. Our hypothesis is that PC cells could induce stromal cells to differentiate into so-called cancer-associated fibroblasts (CAFs), which might contribute to cancer invasion and metastasis. We identified the up-regulated genes in normal human prostate stromal cells (PrSC) co-cultured with human PC cells (LNCaP), which included the mevalonate pathway enzymes 3-hydroxy-3-methylglutaryl-CoA synthase 1 (HMGCS1) and 3-hydroxy-3-methylglutaryl-CoA reductase (HMGCR). Knockdown of endogenous HMGCS1 or HMGCR in PC cells by shRNA resulted in a significant reduction of PC cell viability. Importantly, exogenous overexpression of HMGCS1 or HMGCR in either PC cells or prostate stromal cells stimulated PC cell growth, suggesting a possible autocrine/paracrine regulation. Immunohistochemical analysis confirmed that HMGCS1 and HMGCR were overexpressed in PC stroma, especially in the early stage of PC. These results provide clues to the molecular mechanisms underlying PC invasion and metastasis, and suggest that HMGCS1 and HMGCR in PC, as well as in PC stroma, might serve as molecular targets for the treatment of PC. Citation Format: Shingo Ashida, Chiaki Kawada, Keiji Inoue. Stromal regulation of prostate cancer cell proliferation by mevalonate pathway enzymes HMGCS1 and HMGCR [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 79.

Stromal regulation of prostate cancer cell growth by mevalonate pathway enzymes HMGCS1 and HMGCR.

It has been suggested that the tumor microenvironment plays an important role in tumor progression, acquisition of androgen independence, and distant metastasis in prostate cancer (PC). However, little is known about the transcriptional basis of cellular interactions in the human PC microenvironment. To clarify the mechanism of PC progression and metastasis, we investigated the interaction of PC, epithelial, and stromal cells using genome-wide gene expression profiling. We hypothesized that PC cells could induce stromal cells to differentiate into so-called cancer-associated fibroblasts (CAFs), which might contribute to cancer invasion and metastasis. Genes upregulated in normal human prostate stromal cells (PrSC) co-cultured with human PC cells (LNCaP) included the mevalonate pathway enzymes 3-hydroxy-3-methylglutaryl-CoA synthase 1 (HMGCS1) and 3-hydroxy-3-methylglutaryl-CoA reductase (HMGCR). Knockdown of endogenous HMGCS1 or HMGCR in PC cells by shRNA resulted in a significant reduction of PC cell viability. Importantly, exogenous overexpression of HMGCS1 or HMGCR in either PC cells or prostate stromal cells stimulated PC cell growth, suggesting a possible autocrine/paracrine mechanism of action. Immunohistochemical analysis confirmed that HMGCS1 and HMGCR were overexpressed in PC stroma, especially in early stage PC. These results provide clues to the molecular mechanisms underlying PC invasion and metastasis, and suggest that HMGCS1 and HMGCR in PC, as well as in PC stroma, might serve as molecular targets for the treatment of PC.

Abstract 1698: ERG protein expression and genomic rearrangement status in primary and metastatic prostate cancer - A comparative study of two monoclonal antibodies

Abstract Introduction and Objective: Overexpression of the ERG protein is highly prevalent in prostate cancer (PCa) and most commonly results from gene fusions involving the ERG gene. Recently, an N-terminal epitope targeted mouse and a C-terminal epitope targeted rabbit monoclonal anti-ERG antibody have been introduced for the detection of the ERG protein. Independent studies reported that immunohistochemical (IHC) stains with both monoclonal anti-ERG antibodies (ERG-MAbs) highly correlate with the underlying ERG gene rearrangement status. However, a comparative study of both antibodies has not been provided so far. Here, we are the first to compare the mouse ERG-MAb to the rabbit ERG-MAb for their concordance on the same PCa cohort. Furthermore, we assessed if the ERG protein expression is conserved in lymph node and distant PCa metastases, of which a subset underwent decalcification. Methods: We evaluated tissue microarrays of 278 specimens containing 265 localized PCa, 29 lymph node, 30 distant metastases, and 13 normal prostatic tissues. We correlated the ERG protein expression with the ERG rearrangement status using an ERG break-apart fluorescence in-situ hybridization (FISH) assay and IHC of both ERG antibodies. Results: ERG protein expression and ERG rearrangement status were highly concordant regardless of whether the mouse or rabbit ERG-MAb was used (97.8% versus 98.6%, respectively). Of interest, both ERG antibodies reliably detected the ERG expression in lymph node and distant PCa metastases, of which a subset underwent decalcification. If an ERG protein expression was present in localized PCa, we observed the same pattern in the corresponding lymph node metastases. Conclusions: This is the first study to comprehensively compare the two available ERG-MAbs. By demonstrating a broad applicability of IHC to study ERG protein expression using either antibody, this study adds an important step towards a facilitated routine clinical application. Further, we demonstrate that the clonal nature of the ERG rearrangement is not restricted to the genomic level, but proceeds in the proteome. Together, our results simplify future efforts to further elucidate the biological role of ERG in PCa. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 1698. doi:1538-7445.AM2012-1698

Abstract A30: ERG protein expression and genomic rearrangement status in primary and metastatic prostate cancer a comparative study of two monoclonal antibodies.

Abstract Introduction and Objective: Overexpression of the ERG protein is highly prevalent in prostate cancer (PCa) and most commonly results from gene fusions involving the ERG gene. Recently, an N-terminal epitope targeted mouse and a C-terminal epitope targeted rabbit monoclonal anti-ERG antibody have been introduced for the detection of the ERG protein. Independent studies reported that immunohistochemical (IHC) stains with both monoclonal anti-ERG antibodies (ERG-MAbs) highly correlate with the underlying ERG gene rearrangement status. However, a comparative study of both antibodies has not been provided so far. Here, we are the first to compare the mouse ERG-MAb to the rabbit ERG-MAb for their concordance on the same PCa cohort. Furthermore, we assessed if the ERG protein expression is conserved in lymph node and distant PCa metastases, of which a subset underwent decalcification. Methods: We evaluated tissue microarrays of 278 specimens containing 265 localized PCa, 29 lymph node, 30 distant metastases, and 13 normal prostatic tissues. We correlated the ERG protein expression with the ERG rearrangement status using an ERG break-apart fluorescence in-situ hybridization (FISH) assay and IHC of both ERG antibodies. Results: ERG protein expression and ERG rearrangement status were highly concordant regardless of whether the mouse or rabbit ERG-MAb was used (97.8% versus 98.6%, respectively). Of interest, both ERG antibodies reliably detected the ERG expression in lymph node and distant PCa metastases, of which a subset underwent decalcification. If an ERG protein expression was present in localized PCa, we observed the same pattern in the corresponding lymph node metastases. Conclusions: This is the first study to comprehensively compare the two available ERG-MAbs. By demonstrating a broad applicability of IHC to study ERG protein expression using either antibody, this study adds an important step towards a facilitated routine clinical application. Further, we demonstrate that the clonal nature of the ERG rearrangement is not restricted to the genomic level, but proceeds in the proteome. Together, our results simplify future efforts to further elucidate the biological role of ERG in PCa. Citation Format: Taduru Sreenath, Falko Fend, Nicolas Wernert, Glen Kristiansen, Sven Perner, Shyh-Han Tan, Sr., Martin Braun, Diane Goltz, Zaki Shaikibrahim, Wenzel Vogel, Diana Boehm, Veit Scheble, Albert Dobi. ERG protein expression and genomic rearrangement status in primary and metastatic prostate cancer a comparative study of two monoclonal antibodies [abstract]. In: Proceedings of the AACR Special Conference on Advances in Prostate Cancer Research; 2012 Feb 6-9; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2012;72(4 Suppl):Abstract nr A30.

ERG protein expression and genomic rearrangement status in primary and metastatic prostate cancer—a comparative study of two monoclonal antibodies

Overexpression of the ERG protein is highly prevalent in prostate cancer (PCa) and commonly results from gene fusions involving the ERG gene. Recently, N-terminal epitope-targeted mouse and a C-terminal epitope-targeted rabbit monoclonal anti-ERG antibody (ERG-MAbs) have been introduced for the detection of the ERG protein. Independent studies reported that immunohistochemistry (IHC) with both ERG-MAbs highly correlates with the underlying ERG gene rearrangement status. However, comparative studies of both antibodies are lacking. Here, we are among the first to compare the mouse ERG-MAb with the rabbit ERG-MAb for their concordance on the same PCa cohort. Furthermore, we assessed whether the ERG protein expression is conserved in lymph node and distant PCa metastases. We evaluated tissue microarrays of 278 specimens containing 265 localized PCa, 29 lymph node, 30 distant metastases and 13 normal prostatic tissues. We correlated ERG protein expression with ERG rearrangement status using an ERG break-apart fluorescence in-situ hybridization assay and IHC of both ERG-MAbs. ERG expression and ERG rearrangement status were highly concordant regardless of whether the mouse or rabbit ERG-MAb was used (97.8% versus 98.6%, respectively). Of interest, both ERG antibodies reliably detected the ERG expression in lymph node and distant PCa metastases, of which a subset underwent decalcification. Lymphocytes only revealed immunoreactivity using the rabbit ERG-MAb. If ERG protein expression was present in localized PCa, we observed the same pattern in the corresponding lymph node metastases. By demonstrating a broad applicability of IHC to study ERG protein expression using either antibody, this study adds an important step toward a facilitated routine clinical application. Further, we demonstrate that the clonal nature of the ERG rearrangement is not restricted to the genomic level, but proceeds in the proteome. Together, our results simplify future efforts to further eliucidate the biological role of ERG in PCa.

Comparative evaluation of synthetic anti-HER2 Affibody molecules site-specifically labelled with 111In using N-terminal DOTA, NOTA and NODAGA chelators in mice bearing prostate cancer xenografts

In disseminated prostate cancer, expression of human epidermal growth factor receptor type 2 (HER2) is one of the pathways to androgen independence. Radionuclide molecular imaging of HER2 expression in disseminated prostate cancer might identify patients for HER2-targeted therapy. Affibody molecules are small (7 kDa) targeting proteins with high potential as tracers for radionuclide imaging. The goal of this study was to develop an optimal Affibody-based tracer for visualization of HER2 expression in prostate cancer. A synthetic variant of the anti-HER2 Z(HER2:342) Affibody molecule, Z(HER2:S1), was N-terminally conjugated with the chelators DOTA, NOTA and NODAGA. The conjugated proteins were biophysically characterized by electrospray ionization mass spectroscopy (ESI-MS), circular dichroism (CD) spectroscopy and surface plasmon resonance (SPR)-based biosensor analysis. After labelling with (111)In, the biodistribution was assessed in normal mice and the two most promising conjugates were further evaluated for tumour targeting in mice bearing DU-145 prostate cancer xenografts. The HER2-binding equilibrium dissociation constants were 130, 140 and 90 pM for DOTA-Z(HER2:S1), NOTA-Z(HER2:S1) and NODAGA-Z(HER2:S1), respectively. A comparative study of (111)In-labelled DOTA-Z(HER2:S1), NOTA-Z(HER2:S1) and NODAGA-Z(HER2:S1) in normal mice demonstrated a substantial influence of the chelators on the biodistribution properties of the conjugates. (111)In-NODAGA-Z(HER2:S1) had the most rapid clearance from blood and healthy tissues. (111)In-NOTA-Z(HER2:S1) showed high hepatic uptake and was excluded from further evaluation. (111)In-DOTA-Z(HER2:S1) and (111)In-NODAGA-Z(HER2:S1) demonstrated specific uptake in DU-145 prostate cancer xenografts in nude mice. The tumour uptake of (111)In-NODAGA-Z(HER2:S1), 5.6 ± 0.4%ID/g, was significantly lower than the uptake of (111)In-DOTA-Z(HER2:S1), 7.4 ± 0.5%ID/g, presumably because of lower bioavailability due to more rapid clearance. (111)In-NODAGA-Z(HER2:S1) provided higher tumour-to-blood ratio, but somewhat lower tumour-to-liver, tumour-to-spleen and tumour-to-bone ratios. Since distant prostate cancer metastases are situated in bone or bone marrow, the higher tumour-to-bone ratio is the most important. This renders (111)In-DOTA-Z(HER2:S1) a preferable agent for imaging of HER2 expression in disseminated prostate cancer.

Activated STAT3 as a Correlate of Distant Metastasis in Prostate Cancer: A Secondary Analysis of Radiation Therapy Oncology Group 86-10

STAT3 participates in the regulation of cellular growth, survival, and oncogenesis. We evaluated the association between activated STAT3 expression and overall survival, disease-specific survival, distant metastasis, and local progression in a cohort of patients treated with either radiotherapy alone or radiotherapy plus short-term androgen blockade. A total of 456 assessable patients were included in the Radiation Therapy Oncology Group 86-10 trial. Of these, 62 patients had sufficient tissue for the analysis of STAT3 expression by immunohistochemistry. Nuclear staining was quantified by an image analysis system. No significant difference was found in the distribution of clinical characteristics and assigned treatment between the patients available for STAT3 analysis (STAT3 cohort) and the others in the Radiation Therapy Oncology Group 86-10 trial (n = 394). Activated STAT3 correlated inversely with the development of distant metastasis (risk ratio [RR] = 0.81, P = 0.04) but not with overall survival, cause-specific survival, or local progression. Similar results were obtained when the data were dichotomized (ACIS index greater than 29%, RR = 0.41, P = 0.07). On multivariate analysis, activated STAT3 (continuous variable) was an independent predictor of distant metastasis (RR = 0.79, P = 0.04). Activated STAT3 was inversely related to the development of distant metastasis in prostate cancer. This marker should be evaluated further in a larger cohort of patients.

Stat3 as a correlate of distant metastasis in RTOG 86–10

4656 Background: Stat3 participates in the regulation of cellular growth, survival and oncogenesis. We evaluated Stat3 as a prognostic factor in prostate cancer, by determining Stat3 activity in a cohort of patients treated on RTOG 86–10, a phase III trial that randomized prostate cancer patients between RT alone and RT and short-term androgen blockade. Methods: 62 patients with sufficient tissue were stained with phospho-Stat3 antibody. Stat3 activity was quantified manually and with an image analysis system (ACIS, Chromavision, San Juan Capistrano, CA). Nuclear Stat3 staining was considered positive. The results were correlated with overall mortality (OM), cause specific mortality (CSM), local progression (LP) and distant metastasis (DM) rate. Statistical comparisons were carried out using the chi-square test and Cox proportional hazards models. Stat3 activity quantified using the ACIS Index (percentage positive) was modeled as a continuous variable. ACIS Index cut-points were also tested (the median, the 25% and 75% Quartile) using univariate models of all four endpoints. Estimates for OM and CSM were calculated using the Kaplan-Meier method. The cumulative incidence method was used to estimate LP and DM failure rates. Results: There was no significant difference in the distribution of clinical characteristics and assigned treatment between the patients available for Stat3 analysis (Stat3 cohort) and the others in RTOG 86–10 (n=394). However, the Stat3 cohort had a higher risk for development of DM (RR=1.53, p=0.02) and worse CSM (p=0.04). When treated as a continuous variable, Stat3 activity, as determined by the ACIS-Index, was correlated with the development of DM (RR=0.81, p=0.04) but not with OM, CSM or LP. Similar results were obtained when the data were dichotomized (ACIS Index, ≤29% vs. >29%, 5-yr DM Rate 53.2% vs. 26.7%, p=0.07). Finally, there was no difference in the distribution of clinical and prognostic variables between patients with Stat3-Index > 29% and those with Stat3-Index ≤ 29%. Conclusions: Stat3 activity is correlated with the development of distant metastasis in prostate cancer. This marker should be further evaluated in a larger cohort of patients. Author Disclosure Employment or Leadership Consultant or Advisory Role Stock Ownership Honoraria Research Funding Expert Testimony Other Remuneration RTOG