Recently, a database of human piRNAs (piwi-interacting RNAs) was created, which allows the study of the binding of many piRNAs to the mRNAs of genes involved in many diseases, including cancer. In the present work, we identified the piRNAs that can interact with candidate esophageal squamous cell carcinoma (ESCC) genes. The binding of 480 thousand piRNAs with the mRNAs of 66 candidate ESCC genes was studied. Bioinformatic studies found that piRNAs bind only to the mRNAs of nine candidate genes: AURKA, BMP7, GCOM1, ERCC1, MTHFR, SASH1, SIX4, SULT1A1, and TP53. It has been shown that piRNAs can bind to mRNA by overlapping nucleotide sequences in limited 3′UTR and 5′UTR regions called clusters of binding sites (BSs). The existence of clusters of piRNA BSs significantly reduces the proportion of the nucleotide sequences of these sites in the mRNA of target genes. Competition between piRNAs occurs for binding to the mRNA of target genes. Individual piRNAs and groups of piRNAs that have separate BSs and clusters of BSs in the mRNAs of two or more candidate genes have been identified in the mRNAs of these genes. This organization of piRNAs BSs indicates the interdependence of the expression of candidate genes through piRNAs. Significant differences in the ability of genes to interact with piRNAs prevent the side effects of piRNAs on genes with a lack of the ability to bind such piRNAs. Individual piRNAs and sets of piRNAs are proposed and recommended for the diagnosis and therapy of ESCC.

The problem of increasing life expectancy is solved with the help of many medical and social areas. It has been established that piRNAs and miRNAs can significantly modify the expression of protein-coding genes by suppressing the translation process. The aim of this work was to establish the possibility of binding piRNAs and miRNAs with mRNA of the KLOTHO and FGF23 genes, which promote health and increase life expectancy through participation in key metabolic processes. We used the MirTarget program, which determines the quantitative characteristics of complementary interactions of all piRNAs and miRNAs nucleotides with mRNA of the genes. piR-44682, piR-1940042, piR-3008660, piR-3215034, piR-6885965, piR-7980636 and one miRNA (ID00756.3p-miR) binding to the mRNA of the KLOTHO gene were found in one cluster of binding sites (BSs). piRNA-6890096 interacted with the mRNA of KLOTHO gene in a fully complementary manner using only canonical nucleotides. Among 17494 human genes, target genes interacting with five piRNAs that bind to the mRNA of KLOTHO gene were identified. mRNA of the AFF2, BCL2L11, CPT1A, DAZAP1, NDRG3, SKIDA1, WBP4, ZIC5, ZSWIM6 genes interacted with piR-3215034 and piR-6885965, which formed clusters of BSs located in 5'UTR, CDS and 3'UTR. The piR-576442, piR-1501557, piR-1845735, piR-2069834, and piR-3029987 had BSs in the mRNAs of the FGF23 gene, located only in the 3'UTR. It is proposed to use piRNAs and miRNAs as regulators of the expression of KLOTHO and FGF23 anti-aging genes.