Table 1.
Baseline Characteristics of 2,363 prostate cancer patients included in the IHC study*.
Figure 1.
SSTR2 immunohistochemistry in normal prostate tissue and prostate cancer.
Microphotographs of tissue microarray cores showing normal prostate and prostate cancer tissues: SSTR2-positive normal epithelium (A), SSTR2-negative (B) and SSTR2-positive prostate cancer tissue (C) as well as SSTR2-negative cancer cells next to strongly SSTR2-positive normal epithelial cells (D).
Table 2.
SSTR2 IHC intensities and frequencies in patients with radical prostatectomy.
Figure 2.
Ki67 labeling index and SSTR2 immunohistochemistry (IHC) in prostate cancer cells.
Ki67 labeling index shows a strong inverse correlation with SSTR2 staining intensities (p<0.0001, ANOVA, Dunn’s multiple comparison post-hoc test, box-and-whiskers graph plotting median, 25th and 75th percentile, ** = p<0.01 vs. negative SSTR2 IHC, *** = p<0.001 vs. negative SSTR2 IHC).
Figure 3.
In silico analysis of SSTR gene expression in prostate cancers.
Gene expression analysis of SSTR subtypes in primary prostate cancer tissues versus normal adjacent prostate tissues shows increased SSTR4 (p = 0.0236) and confirms lower SSTR2 expression (p = 0.0424) in primary prostate cancers when comparing all available samples with each other (A, n = 65 vs. 63 patients) or corresponding samples from the same patients only (B, n = 58). Levels of SSTR3 and SSTR5 expression are unchanged (p>0.05). A heatmap of relative SSTR2 gene expression in prostate cancer tissue (tumor) and the surrounding adjacent normal prostate (norm. adj.) per individual patient (column) is shown in (C). SSTR2 expression is also lower in prostate cancer metastases vs. primary tumor (D, p = 0.0011, n = 25) and in recurrent compared with non-recurrent prostate cancers (E, p = 0.0438, n = 39 vs. 40 patients). Standardized expression values were extracted from the identified GEO datasets GDS2545 [18], [19] and GDS4109 [20] and compared as described in the Methods section (Data given as Mean ± SEM; * = p<0.05 vs. corresponding control, ** = p<0.01 vs. corresponding control).
Figure 4.
pT stage and event-free survival in prostate cancer patients.
Kaplan-Meier curves showing pT stage dependence of PSA-recurrence free survival (A), metastasis-free survival (B) and cancer-specific survival (C, all p<0.0001, Log-Rank test) in radically prostatectomized prostate cancer patients.
Table 3.
Association of clinico-pathological features of prostate cancer samples included in this study with PSA recurrence, cancer-specific survival and time to onset of metastatic disease.
Figure 5.
Clinical impact of SSTR2 staining on event-free survival.
PSA recurrence-free survival gradually declines from strong staining of cancer spots over moderate and weak to SSTR2-negative prostate cancers (A, p = 0.0009, Kaplan-Meier analysis with Log-Rank test). Prostatectomized patients with SSTR2-negative prostate cancers also have impaired metastasis-free survival (B, p = 0.0452, Kaplan-Meier analysis with Log-Rank test).