Restoration of PPP2CA expression reverses epithelial-to-mesenchymal transition and suppresses prostate tumour growth and metastasis in an orthotopic mouse model.

BACKGROUND: Emergence of castration-resistance in prostate cancer (PCa) is invariably associated with aggressive and metastatic disease. Previously, we reported promotion of castration-resistance upon downregulation of PPP2CA (encoding catalytic subunit of protein phosphatase 2A (PP2A), α-isoform); however, its role in PCa growth and metastasis remained undetermined. METHODS: PPP2CA was overexpressed/silenced in PCa cells by stable transfection. Gene expression was examined by reverse transcription polymerase chain reaction, immunoblot and immunofluorescence analyses, and transcriptional activity measured by luciferase-based promoter-reporter assay. Effect on PCa phenotype was studied in vitro and in orthotopic mouse model, and immunohistochemical/histological analyses performed to assess proliferation/apoptosis and confirm metastatic lesions. RESULTS: An inverse association of PPP2CA expression was observed with epithelial-to-mesenchymal transition (EMT) and aggressive PCa phenotype. PPP2CA restoration resulted in decreased nuclear accumulation and transcriptional activity of ß-catenin/NF-κB, and restitution of their activity abrogated PPP2CA-induced EMT reversal and suppression of PCa invasiveness. Akt mediated PPP2CA loss-induced nuclear accumulation of ß-catenin/NF-κB through inactivation of Gsk3-ß and IκB-α, respectively. Animal studies revealed a suppressive effect of PPP2CA expression on PCa growth and metastasis. CONCLUSIONS: Our findings suggest that PPP2CA downregulation serves as a molecular link between gain of castration-resistance and aggressive PCa phenotype, and its restoration could be an effective preventive/therapeutic approach against the advanced disease.

Using saline solutions for ACE washouts.

We had found that twice-normal saline (2NS) antegrade continence enema (ACE) lavages were better than with normal saline (NS) but caused unpleasant symptoms. We therefore undertook a double-blind crossover study comparing water, NS and 2NS in four children. NS produced no disturbances, but water caused a transient fall in plasma osmolality of 7.3 mosmol/kg at 20 min, and falls in urine sodium and osmolality. With 2NS, the plasma sodium rose by 2.5 mmol/l, the plasma proteins rose by 2.3 g/l and the lavage fluid sodium fell, suggesting that about 10 ml/kg of plasma water had moved into the colonic lumen, and two subjects became thirsty. Five other children did home testing. Their home-produced saline was too concentrated and varied widely, and they found that 30 ml/kg of NS produced the same washout result as 20 ml/kg of 2NS. Carefully made-up NS should be used for lavage, increasing volumes if necessary.