Abstract:
Cancer has the highest incidence according to other diseases nowadays. Various mechanisms take part in carcinogenesis, one of these mechanisms is small non-coding RNAs. Various studies and researchers determined that small non-coding RNAs are the novel and key molecules of cancer development which do not code protein. These RNAs can be classified into three main groups; small interfering RNAs (siRNAs), micro RNAs (miRNAs) and PIWI interacting RNAs (piRNAs). siRNAs are 18-24 nucleotide (nt) in length, dicer dependent and originated from long double stranded RNA. miRNAs are 18-24 nt in length, dicer dependent and originated from miRNA loci which is found in genomic DNA. miRNAs are associated with Argonaute (AGO) proteins for transcriptional repression or degradation of target mRNA. Furthermore, miRNAs might have tumor suppressive or oncogenic functions according to their target gene and its functions. In our studies about miRNAs showed that miR-126 and its complementary miR-126* can be more effective in metastasis and recurrence. Furthermore, piRNAs are 23-31 nt in length, dicer independent and originated from germ and somatic cells, especially germ cells. piRNAs are associated with one of the type of AGO proteins which is called PIWI proteins. Although piRNAs are first thought that they play an important role in embryogenesis (especially spermatogenesis) via transposon silencing, recent studies are shown that they also have effect on cancer development and biology. The expression of piRNAs and PIWI proteins can be effected by various mechanisms of cell. Hormonal regulation is one of these mechanism, one of our researches shows that exogenous estrogen or androgen uptake might cause some cancer types, breast and prostate cancer, to be more aggressive and to affect expression of piRNAs. Furthermore, the researches about miRNAs and piRNAs show that these two non-coding RNAs can be originated from same gene regions and can affect their expressions during carcinogenesis. In the advanced stages of cancer and metastasis; our lifetime is decreasing. Once cancer has metastasized, treatments are becoming ineffective. If we can prevent the aggressiveness and invasiveness of cancer cells earlier (in benign stage) by aiming to prevent metastasis and developing new therapies like gene therapy. We must learn to live with cancer as well as other diseases such as diabetes, hypertension etc.
