Figure 4. Expression of piR-19166 in PCa tissues and cell lines. (A) ISH showed expression of piR-19166 was negative (30/42) compared with the adjacent normal tissues (positive, 35/42). (B) Compared with the negative group of lymph node metastasis (LNM), a significantly low level of piR-19166 was detected in the LNM -positive group by qRT-PCR (Pearson Chi-Square=42.000, **P<0.01). (C) Down-regulation of piR-19166 was detected using qRT-PCR in PC3 (T test, t=33.15, ***P < 0.001) and LNCaP (T test, t=32.05, ***P < 0.001) compared with normal prostate epithelial cell RWPE-1. *P < 0.05, **P < 0.01, ***P < 0.001.