Hui-Ming Lin

Circulating microRNAs are associated with docetaxel chemotherapy outcome in castration-resistant prostate cancer.

Background:Docetaxel is the first-line chemotherapy for castration-resistant prostate cancer (CRPC). However, response rates are ∼50% and determined quite late in the treatment schedule, thus non-responders are subjected to unnecessary toxicity. The potential of circulating microRNAs as early biomarkers of docetaxel response in CRPC patients was investigated in this study.Methods:Global microRNA profiling was performed on docetaxel-resistant and sensitive cell lines to identify candidate circulating microRNA biomarkers. Custom Taqman Array MicroRNA cards were used to measure the levels of 46 candidate microRNAs in plasma/serum samples, collected before and after docetaxel treatment, from 97 CRPC patients.Results:Fourteen microRNAs were associated with serum prostate-specific antigen (PSA) response or overall survival, according to Mann–Whitney U or log-rank tests. Non-responders to docetaxel and patients with shorter survival generally had high pre-docetaxel levels of miR-200 family members or decreased/unchanged post-docetaxel levels of miR-17 family members. Multivariate Cox regression with bootstrapping validation showed that pre-docetaxel miR-200b levels, post-docetaxel change in miR-20a levels, pre-docetaxel haemoglobin levels and visceral metastasis were independent predictors of overall survival when modelled together.Conclusions:Our study suggests that circulating microRNAs are potential early predictors of docetaxel chemotherapy outcome, and warrant further investigation in clinical trials.

Phosphoproteomic Profiling Identifies Focal Adhesion Kinase as a Mediator of Docetaxel Resistance in Castrate-Resistant Prostate Cancer

Docetaxel remains the standard-of-care for men diagnosed with metastatic castrate-resistant prostate cancer (CRPC). However, only approximately 50% of patients benefit from treatment and all develop docetaxel-resistant disease. Here, we characterize global perturbations in tyrosine kinase signaling associated with docetaxel resistance and thereby develop a potential therapeutic strategy to reverse this phenotype. Using quantitative mass spectrometry–based phosphoproteomics, we identified that metastatic docetaxel-resistant prostate cancer cell lines (DU145-Rx and PC3-Rx) exhibit increased phosphorylation of focal adhesion kinase (FAK) on Y397 and Y576, in comparison with parental controls (DU145 and PC3, respectively). Bioinformatic analyses identified perturbations in pathways regulating focal adhesions and the actin cytoskeleton and in protein–protein interaction networks related to these pathways in docetaxel-resistant cells. Treatment with the FAK tyrosine kinase inhibitor (TKI) PF-00562271 reduced FAK phosphorylation in the resistant cells, but did not affect cell viability or Akt phosphorylation. Docetaxel administration reduced FAK and Akt phosphorylation, whereas cotreatment with PF-00562271 and docetaxel resulted in an additive attenuation of FAK and Akt phosphorylation and overcame the chemoresistant phenotype. The enhanced efficacy of cotreatment was due to increased autophagic cell death, rather than apoptosis. These data strongly support that enhanced FAK activation mediates chemoresistance in CRPC, and identify a potential clinical niche for FAK TKIs, where coadministration with docetaxel may be used in patients with CRPC to overcome chemoresistance. Mol Cancer Ther; 13(1); 190–201. ©2013 AACR.

Cytokine profiling of docetaxel-resistant castration-resistant prostate cancer

Background:Docetaxel improves symptoms and survival in metastatic castration-resistant prostate cancer (CRPC). However, ∼50% of patients are chemoresistant. This study examined whether changes in cytokine levels predict for docetaxel resistance in vitro and in a clinical cohort.Methods:PC3 cells or their docetaxel-resistant subline (PC3Rx) were co-cultured with U937 monocytes, with and without docetaxel treatment, and cytokine levels were measured. The circulating levels of 28 cytokines were measured pre-/post cycle 1 of docetaxel from 55 men with CRPC, and compared with prostate-specific antigen (PSA) response.Results:PC3Rx-U937 co-culture expressed more cytokines, chiefly markers of alternative macrophage differentiation, compared with PC3-U937 co-culture. Docetaxel treatment enhanced cytokine production by PC3Rx-U937 co-culture, while reducing cytokine levels in PC3-U937. In patients, changes in the levels of seven circulating cytokines (macrophage inhibitory cytokine 1 (MIC1), interleukin (IL)-1ra, IL-1β, IL-4, IL-6, IL-12 and IFNγ) after cycle 1 of docetaxel were associated with progressive disease (all P<0.05). The combination of changes in MIC1, IL-4 and IL-6 most strongly predicted PSA response (P=0.002).Conclusions:In vitro studies suggest docetaxel resistance is mediated, at least in part, by cytokines induced by the interaction between the docetaxel-resistant tumour cells and macrophages. Early changes in circulating cytokine levels were associated with docetaxel resistance in CRPC patients. When considered together, these data suggest a significant role for the inflammatory response and macrophages in the development of docetaxel resistance in CRPC.

Phase 2 study of circulating microRNA biomarkers in castration-resistant prostate cancer

Background:Biomarkers of therapeutic response and prognosis are needed to assist in the sequencing of treatments for metastatic castration-resistant prostate cancer (CRPC). Previously in a Phase 1 discovery study, we identified 14 circulating microRNAs that were associated with response to docetaxel chemotherapy or overall survival. We performed a Phase 2 validation study to verify these findings.Methods:Using real-time PCR, the levels of the 14 microRNAs were measured in plasma collected before and after the first cycle of docetaxel from a Phase 2 cohort of 89 patients.Results:The microRNAs were not associated with docetaxel response in the Phase 2 cohort. Higher baseline levels of six microRNAs, predominantly of the miR-200 family, were confirmed to be associated with shorter overall survival. A microRNA signature comprising these six microRNAs predicted high-risk patients in the Phase 2 cohort with a hazard ratio of 4.12 (95% CI 2.20–7.70, P=0.000001). The signature was an independent predictor in multivariable analysis with clinicopathological factors.Conclusions:The association of circulating microRNAs with overall survival suggests their involvement in CRPC progression.

A distinct plasma lipid signature associated with poor prognosis in castration-resistant prostate cancer

Lipids are known to influence tumour growth, inflammation and chemoresistance. However, the association of circulating lipids with the clinical outcome of metastatic castration‐resistant prostate cancer (CRPC) is unknown. We investigated associations between the plasma lipidome and clinical outcome in CRPC. Lipidomic profiling by liquid chromatography‐tandem mass spectrometry was performed on plasma samples from a Phase 1 discovery cohort of 96 CRPC patients. Results were validated in an independent Phase 2 cohort of 63 CRPC patients. Unsupervised analysis of lipidomic profiles (323 lipid species) classified the Phase 1 cohort into two patient subgroups with significant survival differences (HR 2.31, 95% CI 1.44–3.68, p = 0.0005). The levels of 46 lipids were individually prognostic and were predominantly sphingolipids with higher levels associated with poor prognosis. A prognostic three‐lipid signature was derived (ceramide d18:1/24:1, sphingomyelin d18:2/16:0, phosphatidylcholine 16:0/16:0) and was also associated with shorter survival in the Phase 2 cohort (HR 4.8, 95% CI 2.06–11.1, p = 0.0003). The signature was an independent prognostic factor when modelled with clinicopathological factors or metabolic characteristics. The association of plasma lipids with CRPC prognosis suggests a possible role of these lipids in disease progression. Further research is required to determine if therapeutic modulation of the levels of these lipids by targeting their metabolic pathways may improve patient outcome.

Loss of AZGP1 as a Superior Predictor of Relapse in Margin-Positive Localized Prostate Cancer.

Positive surgical margins (PSMs) in localized prostate cancer (PC) confer a two‐ to three‐fold increased risk of biochemical relapse (BR). Absent/weak AZGP1 expression and Gleason grade ≥4 at the margin are each independent predictors of BR in patients with PSMs. Our study aimed to determine whether the biomarkers AZGP1 expression and Gleason grade at the site of a PSM are significant independent markers of biochemical and clinical relapse (CR) when modeled together and whether one of these biomarkers may be superior in its capacity to predict outcome.