Potential of the Stromal Matricellular Protein Periostin as a Biomarker to Improve Risk Assessment in Prostate Cancer

Figures

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  Figure 1. Periostin is over-expressed in CAFs. (a) Expression levels of POSTN mRNA were assessed by qRT-PCR in a panel of three patient-derived CAFs isolated from the tumoral area of radical prostatectomy samples and matched normal prostate fibroblasts (NPFs) isolated from non-tumoral areas and PCa cell lines (DU145, PC3). Data represented as mean ± SD of three independent experiments with respect to NPF#1 (Mann–Whitney one-sided test, * = p < 0.05). # = undetected values. Ct value of POSTN in NPF#1 is 27. (b) Western blotting analysis showing periostin protein levels in three paired CAFs and NPFs. Quantification, as indicated under the blot, was estimated from the intensity of Western blot signals using the ImageJ software. The periostin/gapdh ratios were relativized to 1 for each paired sample.

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  Figure 2. Periostin stromal staining correlates with tumor aggressiveness and biochemical relapse in PCa patients. (a) Immunohistochemical scoring of periostin in representative PCa samples: undetectable and weak score staining were assigned to low category; medium and strong score staining were included in the high category. Periostin staining was mainly observed in peritumoral areas. Magnification: 200×. (b) Stromal periostin score distribution within prognostic grade groups (PGG) of 116 PCa samples. (c) Periostin stroma staining distribution in 60 GS = 7 (PGG2/3) tumors, classified based on the presence (+) or absence (-) of cribriform morphology. (d) BCR-free survival of 116 PCa patients categorized based on stromal periostin score. In the corresponding table, the number of patients at risk at the different time points for each of the two groups (low and high staining) is reported.

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  Figure 3. Circulating levels of periostin and sparc may be used to improve risk stratification. (a) Protein expression levels of selected stromal proteins were assessed by Western blotting in the conditioned medium from CAFs and NPFs and in plasma samples collected from PCa patients. (b) ELISA–based evaluation of circulating periostin in plasma samples collected at the baseline from 100 AS patients, including 40 who discontinued the program upon upgrading after one year (up–grading group) and 60 who remained in AS for more than 5 years (indolent group), and in 21 patients with clinically significant PCa. The Wilcoxon test was performed and p < 0.05 was considered significant. (c) ELISA–based evaluation of circulating sparc in plasma samples collected at the baseline from 100 AS patients, including 40 who discontinued the program upon upgrading after one year (up-grading group) and 60 who remained in AS for more than 5 years (indolent group). The Wilcoxon test was performed and p < 0.05 was considered significant. (d) ROC curves and corresponding AUCs derived from the index score models built on clinico–pathological variables only and upon addition of circulating sparc and periostin in 100…