Table 1.

The Role of piRNAs in various Cancer

piRNA	Cancer type	Function	Expression in tumors	Reference
piR-36712	Breast cancer	suppressed cell proliferation, invasion and migration by combining with SEPW1P RNA	down	[22]
piR-021285		inhibited cell proliferation and invasion by ARHGAP11A methylation	down	[35]
piR-932		caused EMT through promoting promoter region CpG island methylation of Latexin	up	[46]
piR-DQ598677		form pi-RISC to degrade targeted genes like miRNAs	down	[47]
piR-34871 piR-52200	Lung cancer	correlated with RASSF1C expression, promoted cell proliferation and colony formation by reducing AMPK phosphorylation of ATM-AMPK-p53-p21cip pathway	up	[17]
piR-35127 piR-46545			down
piR-651		Promoted cells and tumor proliferation and inhibited apoptosis, induced cyclin D1 and CDK4 expression	up	[48, 49]
piR-55490		inhibited LC cells and tumor proliferation by binding 3’UTR of mTOR mRNA	down	[37]
piR-823	Gastric cancer	inhibited proliferation of cancer cells, and caused cells aberrant “stem-like”state by weakening tumor supporter genes methylation	down	[19, 50]
piR-651		promote cell proliferation and associated with TNM stages	up	[51]
piR- FR222326		positively associated with overall survival	up	[52]
piR-FR290353 piR-FR064000 piR-FR387750		associated with recurrence-free survival	up	[52]
piR-1245	Colorectal cancer	accelerated cell growth, promoted migration and invasion as well as anti-apoptosis by binding to its downstream targeted mRNA in nuclear exosomes, associated with poor differentiation, TNM state and poor overall survival	up	[53]
piR-54265		promoted proliferation and metastasis, inhibited apoptosis, correlated with shorter progression-free survival time and overall survival time, caused therapy resistance to anti-tumor agents by regulating STAT3 phosphorylation	up	[45]
piR-823		enhanced cells proliferation and suppressed apoptosis by promoting HSF1 phosphorylation at Ser326 and inducing Stat3 phosphorylation	up	[44]
piR-015551		influenced the colorectal cancer development by causing gene mutation	up	[54]
piR-Hep1	Hepatocellular carcinoma	promoted cells proliferation and invasion via upregulating phosphorylated AKT of PI3K/AKT signaling pathway	up	[55]
piR-LLi-24894		asssociated with low-grade lesions of hepatocellular carcinoma	up	[56]
Hsa-piR-013306		involved in the hepatic carcinogenic process	up	[56]
piR-32051 piR-39894 piR-43607	Kidney cancer	linked with renal cell carcinoma of high tumor stage and metastasis and cancer-specific survival	up	[57]
piR-57125		inhibited cancer metastatic	down	[58]
piR-30924 piR-38756		associated with cancer metastatic	up/down	[58]
piR-823	Hematological malignancy	promoted proliferation, inhibited apoptosis and modulated cell cycle progression of multiple myeloma cells by regulating DNA methylation and angiogenesis	up	[36]
		improved the survival and maintained the stemness of multiple myeloma stem cells by producing more DNMT3B	up	[59]
		promoted the proliferation, migration, and capillary structure formation of tumor-associated endothelial cells	up	[60]
piR-651		associated with shorter disease-free survival and shorter overall survival in classical Hodgkin lymphoma patients	up	[61]
piR-30188	Glioblastoma	supressed tumor cell proliferation, invasion and migration and promoted apoptosis by binding to OIP5-AS1	down	[38]
piR-8041		Promoted cells proliferation and inhibited death by interacting with the mRNA MAPK	down	[62]
piR-DQ593109		increased the permeability of the blood-tumor barrier and promoted the delivery of therapeutics into the glioma micro-environment via bindind to MEG3	down	[63]
piR-DQ590027		increased the permeability of glioma-conditioned normal blood-brain barrier and promoted the transport of macromolecular chemotherapeutics into glioma tissues by binding to MIR17HG	down	[64]
piR-39980	Fibrosarcoma	inhibition of cell proliferation via interacting with RRM2	down	[65]
piR-52207	Ovarian cancer	promoted cell proliferation, migration and tumorigenesis by binding to targeted mRNA (NUDT4, MTR, EIF2S3, MPHOSPH8)	up	[66]
piR-33733		Inhibited cells apoptosis by binding to targeted mRNA (ACTR10, PLEKHA5)	up	[66]
piR-017061	Pancreatic cancer	Not clear	down	[67]