Time resolved amplified FRET identifies protein kinase B activation state as a marker for poor prognosis in clear cell renal cell carcinoma.

Purpose: Clear cell Renal Cell Carcinomas (ccRCC), the largest group of renal tumours, are resistant to classical therapies. The determination of the functional state of actionable biomarkers for the assessment of these adenocarcinomas is essential. The dysregulation of the oncoprotein, PKB/Akt has been linked with poor prognoses in human cancers.

Material & methods: We analysed the status of the PKB/Akt pathway in a representative tumour tissue microarray obtained from the primary tumours and their metastases in 60 ccRCC with long term follow up. We sought to define the evolution of this pathway from the primary tumour to the metastatic event and to know the impact of its functional state in tumour aggressiveness and patient survival. Two-site time resolved amplified FRET (A-FRET) was utilised for assessing the activation state of PKB/Akt and this was compared to conventional immunohistochemistry measurements.

Results: Activation state of PKB/Akt in primary tumours defined by A-FRET correlated with poorer overall survival (hazard ratio 0.228; p  = 0.002). Whereas, increased protein expression of phosphoPKB/Akt, identified using classical immunohistochemistry, yielded no significant difference (hazard ratio 1.390; p  = 0.548).

Conclusions: Quantitative determination of PKB/Akt activation in ccRCC primary tumours alongside other diagnostics tools could prove key in taking oncologists closer to an efficient personalised therapy in ccRCC patients.

General significance: The quantitative imaging technology based on Amplified-FRET can rapidly analyse protein activation states and molecular interactions. It could be used for prognosis and assess drug function during the early cycles of chemotherapy. It enables evaluation of clinical efficiency of personalised cancer treatment.