Table 1.

Experimental studies that investigated the role of piRNAs in breast cancer

PiRNA	Function	Type of breast cancer or its cell line	Model	Expression	References
PiR-36712	Promotes cancer cell proliferation, invasion and migration	Invasive breast ductal carcinoma	In vitro and In vivo	Underexpressed	[79]
PiR-34736	Progression of cell cycle	Invasive breast ductal carcinoma	In vitro	Underexpressed	[82]
PiR-36249	Progression of cell cycle	Invasive breast ductal carcinoma	In vitro	Underexpressed	[82]
PiR-35407	Progression of cell cycle	Invasive breast ductal carcinoma	In vitro	Underexpressed	[82]
PiR-34377	Progression of cell cycle	Invasive breast ductal carcinoma	In vitro	Underexpressed	[82]
PiR-36318	Progression of cell cycle	Invasive breast ductal carcinoma	In vitro	Underexpressed	[82]
PiR-36026	Progression of cell cycle	Invasive breast ductal carcinoma	In vitro	Overexpressed	[82]
PiR-31106	Progression of cell cycle	Invasive breast ductal carcinoma	In vitro	Overexpressed	[82]
PiR-36743	Progression of cell cycle	Invasive breast ductal carcinoma	In vitro	Overexpressed	[82]
PiR-20582	Tumor marker	Invasive breast ductal carcinoma	In vitro	Overexpressed	[83]
PiR-4987	Lymph node positivity	Invasive breast ductal carcinoma	In vitro	Overexpressed	[83]
PiR-20365	Tumor marker	Invasive breast ductal carcinoma	In vitro	Overexpressed	[83]
PiR-20485	Tumor marker	Invasive breast ductal carcinoma	In vitro	Overexpressed	[83]
PiR-651	Tumor progression	Bcap-37 cell line	In vitro	Overexpressed	[39]
PiR-021285	Modulates Breast cancer invasiveness	MCF7 breast cancer cell lines	In vitro	Overexpressed	[78]
PiR-932	Promotes methylation of Latexin and form immune complexes	Breast cancer stem cells(CSC)	In vitro	Overexpressed	[85]