Multi-transcript profiling in archival diagnostic prostate cancer needle biopsies to evaluate biomarkers in non-surgically treated men

Abstract

BackgroundMost biomarkers in prostate cancer have only been evaluated in surgical cohorts. The value of these biomarkers in a different therapy context remains unclear. Our objective was to test a panel of surgical biomarkers for prognostic value in men treated by external beam radiotherapy (EBRT) and primary androgen deprivation therapy (PADT).MethodsThe Fluidigm® PCR array was used for multi-transcript profiling of laser microdissected tumours from archival formalin-fixed diagnostic biopsies of patients treated by EBRT or PADT. Cases were matched for disease characteristics and had known 5 year biochemical relapse outcomes (n = 60). Results were validated by immunohistochemistry in a custom needle biopsy tissue microarray. Six biomarkers previously tested only in surgical cohorts were analysed (PTEN, E-Cadherin, EGFR, EZH2, PSMA, MSMB). Transcript and protein expression was correlated with clinical outcome analysed using Kruskal Wallis, Fisher’s test and Cox proportional hazard model.ResultsAltered expression of E-Cadherin (p = 0.008) was associated with early relapse after EBRT. In PADT treated men however only altered MSMB transcript was prognostic for early relapse (p = 0.001). The remaining biomarkers however did not demonstrate prognostic ability in either cohort. In a separate tissue array we validated altered E-Cadherin protein as a predictor of early relapse after EBRT (n = 47) (HR 0.34, CI p = 0.02) but not in PADT treated men (n = 63).ConclusionWe demonstrate proof of principle of multiple transcript profiling in archival diagnostic biopsies of non-surgically treated men for biomarker discovery. We identify a role for E-Cadherin as a novel biomarker of early relapse following EBRT.

Applying for research funding. Part 2 – Writing a grant application

“…9 Transcript profiling of diagnostic needle biopsies defines therapy-specific biomarkers of outcome in prostate cancer. 10 Multiparametric MRI improves tumour staging and reduces positive margin rates in radical prostatectomy compared with T2weighted MRI alone. 11 AR: androgen receptor; FGF: fibroblast growth factor; MRI: magnetic resonance imaging.…”

Genomic and Histopathological Tissue Biomarkers That Predict Radiotherapy Response in Localised Prostate Cancer

“…IHC is a technique that is readily available in routine pathology laboratories; tumour histopathology can be correlated with protein expression; hence, tumour dissection is not required. For bulky prostate tumours, sufficient tissue may be present to construct tissue microarrays which facilitates high throughput analysis [ 14 , 15 ]; however, in intermediate risk localised prostate tumours this approach has recently been shown to be unfeasible due to inadequate numbers of tumour cells [ 16 ].…”

“…Although amplification can introduce bias, this multiplex technique is particularly useful when tissue and hence nucleic acid quantity is limited. A reduction in mRNA (messenger RNA) of the cell-cell adhesion molecule E-cadherin has recently been associated with poor outcome after radiotherapy, but not after primary androgen deprivation therapy alone using PCR array [ 15 ]. The authors validated the predictive ability of E-cadherin in an independent dataset by demonstrating that reduced protein expression using IHC was significantly and independently associated with early biochemical recurrence.…”

“…A number of other candidates were simultaneously assessed including previously discussed EGFR and PTEN, as well as EZH2, PSMA, and MSMB, all of which have shown prognostic ability following surgery; however, they were non-prognostic after radiotherapy in this study. However, the study cohort size was modest at 60 patients which may have contributed to negative findings [ 15 ]. The fact that AR also showed no prognostic ability after EBRT illustrates the differences in tumour biology between castration resistant and castration sensitive tumours.…”

Transición epitelial-mesenquimal en la progresión del adenocarcinoma prostático

“…TGF-β y Twist1 también mostraron mayor expresión en el tejido con cáncer, inversamente proporcional a la diferenciación del tumor, y tanto su aumento como el de la N-cadherina se correlaciona con niveles más altos de PSA y metás-tasis óseas (72). Además, se ha estudiado su relación con la evolución después del tratamiento, y se ha encontrado asociación entre la pérdida de E-cadherina en el RNA mensajero y la mala respuesta en pacientes sometidos a tratamiento no quirúrgico (73). La expresión aumentada de N-cadherina en un porcentaje considerable de casos de CaP, mayor en los tumores resistentes a la castración y asociada con pérdida o disminución de la expresión del receptor de andró-genos, plantea una posible regulación sobre este y sugiere una ventaja de crecimiento de estas células sobre las N-cadherina negativas (74).…”