Molecular characterization of radical prostatectomy specimens after systemic therapy may identify a gene expression profile for resistance to therapy. This study assessed tumor cells from patients with prostate cancer participating in a phase II neoadjuvant docetaxel and androgen deprivation trial to identify mediators of resistance. Transcriptional level of 93 genes from a docetaxel-resistant prostate cancer cell lines microarray study was analyzed by TaqMan low-density arrays in tumors from patients with high-risk localized prostate cancer (36 surgically treated, 28 with neoadjuvant docetaxel þ androgen deprivation). Gene expression was compared between groups and correlated with clinical outcome. VIM, AR and RELA were validated by immunohistochemistry. CD44 and ZEB1 expression was tested by immunofluorescence in cells and tumor samples. Parental and docetaxel-resistant castration-resistant prostate cancer cell lines were tested for epithelial-to-mesenchymal transition (EMT) markers before and after docetaxel exposure. Reversion of EMT phenotype was investigated as a docetaxel resistance reversion strategy. Expression of 63 (67.7%) genes differed between groups (P < 0.05), including genes related to androgen receptor, NF-kB transcription factor, and EMT. Increased expression of EMT markers correlated with radiologic relapse. Docetaxel-resistant cells had increased EMT and stem-like cell markers expression. ZEB1 siRNA transfection reverted docetaxel resistance and reduced CD44 expression in DU-145R and PC-3R. Before docetaxel exposure, a selected CD44 þ subpopulation of PC-3 cells exhibited EMT phenotype and intrinsic docetaxel resistance; ZEB1/CD44 þ subpopulations were found in tumor cell lines and primary tumors; this correlated with aggressive clinical behavior. This study identifies genes potentially related to chemotherapy resistance and supports evidence of the EMT role in docetaxel resistance and adverse clinical behavior in early prostate cancer. Mol Cancer Ther; 13(5); 1270-84. Ó2014 AACR.

Non-small-cell lung cancer patients with activating epidermal growth factor receptor (EGFR) mutations typically benefit from EGFR tyrosine kinase inhibitor treatment. However, virtually all patients succumb to acquired EGFR tyrosine kinase inhibitor resistance that occurs via diverse mechanisms. The diversity and unpredictability of EGFR tyrosine kinase inhibitor resistance mechanisms presents a challenge for developing new treatments to overcome EGFR tyrosine kinase inhibitor resistance. Here, we show that Akt activation is a convergent feature of acquired EGFR tyrosine kinase inhibitor resistance, across a spectrum of diverse, established upstream resistance mechanisms. Combined treatment with an EGFR tyrosine kinase inhibitor and Akt inhibitor causes apoptosis and synergistic growth inhibition in multiple EGFR tyrosine kinase inhibitor-resistant non-small-cell lung cancer models. Moreover, phospho-Akt levels are increased in most clinical specimens obtained from EGFR-mutant non-small-cell lung cancer patients with acquired EGFR tyrosine kinase inhibitor resistance. Our findings provide a rationale for clinical trials testing Akt and EGFR inhibitor co-treatment in patients with elevated phospho-Akt levels to therapeutically combat the heterogeneity of EGFR tyrosine kinase inhibitor resistance mechanisms.

The cellular and molecular effects of the proteasome inhibitor bortezomib on breast cancer cells are as yet poorly characterized.

Purpose: To investigate whether nuclear factor nB (NF-nB)/interleukin 6 (IL-6) was linked to docetaxel response in human prostate cancer cell lines, and whether inhibition of NF-nB sensitized tumor cells to docetaxel. We also aimed to correlate IL-6 (as a surrogate marker of NF-nB) and docetaxel response in hormone-independent prostate cancer (HIPC) patients. Experimental Design: Hormone-dependent (LNCaP) and hormone-independent (PC-3 and DU-145) prostate cancer cell lines were exposed to docetaxel alone or combined with the NF-nB inhibitor PS-1145 (an inhibitor of InB kinase-2). Effects of dose, exposure time, and schedule dependence were assessed. Activation of NF-nB was assayed by electrophoresis mobility shift assay and luciferase reporter assay, IL-6 levels by ELISA, and cell viability by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay. Cell cycle and apoptosis were assessed by fluorescence-activated cell sorting analysis. Apoptosis was also measured by detection of cleavage of poly(ADP-ribose) polymerase. In patients with metastatic HIPC receiving docetaxelbased chemotherapy, IL-6 serum levels were assayed before chemotherapy and every 3 to 4 weeks thereafter. Results: PC-3 and DU-145 cells had higher NF-nB activity, secreted more IL-6, and were more resistant to docetaxel than LNCaP cells. NF-nB activity was induced by docetaxel. Cotreatment with docetaxel and PS-1145 prevented docetaxel-induced NF-nB activation, reduced IL-6 production, and increased docetaxel effects on cell viability in PC-3 and DU-145 cells but not in LNCaP. Synergism with docetaxel and PS-1145, as assayed by median-effect principle, was observed in DU-145 and PC-3. In HIPC patients, pretreatment IL-6 serum levels correlated to prostate-specific antigen (PSA) response: median IL-6 level was 10.8 F 9.5 pg/mL in PSA responders versus 36.7 F 20.8 pg/mL (P = 0.006) in nonresponders. A PSA response was also linked to a decline in IL-6 levels during treatment. Median overall survival was 6.8 months in patients with high IL-6 versus 16.6 months in those with low IL-6 (P = 0.0007). On multivariate analysis, pretreatment IL-6 (P = 0.05) was an independent prognostic factor for time to disease progression and survival. Conclusions: Inhibition of NF-nB emerges as an attractive strategy to enhance docetaxel response in prostate cancer. The interest of this view is further supported by a significant association between high IL-6 in sera of HIPC patients and decreased response to docetaxel.

Nuclear factor (NF)-kB/p65 regulates the transcription of a wide variety of genes involved in cell survival, invasion and metastasis. We characterised by immunohistochemistry the expression of NF-kB/p65 protein in six histologically normal prostate, 13 high-grade prostatic intraepithelial neoplasia (PIN) and 86 prostate adenocarcinoma specimens. Nuclear localisation of p65 was used as a measure of NF-kB active state. Nuclear localisation of NF-kB was only seen in scattered basal cells in normal prostate glands. Prostatic intraepithelial neoplasias exhibited diffuse and strong cytoplasmic staining but no nuclear staining. In prostate adenocarcinomas, cytoplasmic NF-kB was detected in 57 (66.3%) specimens, and nuclear NF-kB (activated) in 47 (54.7%). Nuclear and cytoplasmic NF-kB staining was not correlated (P ¼ 0.19). By univariate analysis, nuclear localisation of NF-kB was associated with biochemical relapse (P ¼ 0.0009; log-rank test) while cytoplasmic expression did not. On multivariate analysis, serum preoperative prostate specific antigen (P ¼ 0.02), Gleason score (P ¼ 0.03) and nuclear NF-kB (P ¼ 0.002) were independent predictors of biochemical relapse. These results provide novel evidence for NF-kB/p65 nuclear translocation in the transition from PIN to prostate cancer. Our findings also indicate that nuclear localisation of NF-kB is an independent prognostic factor of biochemical relapse in prostate cancer.