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Epigenetic loss of the PIWI/piRNA machinery in human testicular tumorigenesis.

Ferreira HJ, Heyn H, Garcia del Muro X, Vidal A, Larriba S, Muñoz C, Villanueva A, Esteller M - Epigenetics (2013)

Bottom Line: Although most cancer research has focused in mRNA, non-coding RNAs are also an essential player in tumorigenesis.Herein we have studied the putative existence of epigenetic aberrations in the activity of PIWI proteins, an Argonaute family protein subclass, and the small regulatory PIWI-interacting RNAs (piRNAs) in testicular cancer, as the PIWI/piRNA pathway plays a critical role in male germline development.We have observed the existence of promoter CpG island hypermethylation-associated silencing of PIWIL1, PIWIL2, PIWIL4, and TDRD1 in primary seminoma and non-seminoma testicular tumors, in addition to testicular germ cell tumor cell lines.

View Article: PubMed Central - PubMed

Affiliation: Cancer Epigenetics and Biology Program (PEBC); Bellvitge Biomedical Research Institute (IDIBELL); Barcelona, Spain; Programme in Experimental Biology and Biomedicine; Centre for Neurosciences and Cell Biology; University of Coimbra; Coimbra, Portugal.

ABSTRACT
Although most cancer research has focused in mRNA, non-coding RNAs are also an essential player in tumorigenesis. In addition to the well-recognized microRNAs, recent studies have also shown that epigenetic silencing by CpG island hypermethylation of other classes of non-coding RNAs, such as transcribed ultraconserved regions (T-UCRs) or small nucleolar RNAs (snoRNAs), also occur in human neoplasia. Herein we have studied the putative existence of epigenetic aberrations in the activity of PIWI proteins, an Argonaute family protein subclass, and the small regulatory PIWI-interacting RNAs (piRNAs) in testicular cancer, as the PIWI/piRNA pathway plays a critical role in male germline development. We have observed the existence of promoter CpG island hypermethylation-associated silencing of PIWIL1, PIWIL2, PIWIL4, and TDRD1 in primary seminoma and non-seminoma testicular tumors, in addition to testicular germ cell tumor cell lines. Most importantly, these epigenetic lesions occur in a context of piRNA downregulation and loss of DNA methylation of the LINE-1 repetitive sequences, one of the target genomic loci where the PIWI/piRNA machinery acts as a caretaker in non-transformed cells.

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Figure 2. Epigenetic inactivation of genes encoding piRNA-related proteins in testicular germ cell tumor lines. (A) DNA methylation levels at the 5′end CpG islands of the PIWIL1, PIWIL2, PIWIL4 and TDRD1 genes determined by sodium bisulfite modification coupled to hybridization to a DNA microarray (450K Illumina). DNA methylation levels are color-coded (red: high, green: low). Probe distances to the transcription start site (TSS) are indicated. (B) mRNA expression levels of the PIWIL1, PIWIL2, PIWIL4 and TDRD1 genes determined by quantitative reverse transcription PCR.
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Figure 2: Figure 2. Epigenetic inactivation of genes encoding piRNA-related proteins in testicular germ cell tumor lines. (A) DNA methylation levels at the 5′end CpG islands of the PIWIL1, PIWIL2, PIWIL4 and TDRD1 genes determined by sodium bisulfite modification coupled to hybridization to a DNA microarray (450K Illumina). DNA methylation levels are color-coded (red: high, green: low). Probe distances to the transcription start site (TSS) are indicated. (B) mRNA expression levels of the PIWIL1, PIWIL2, PIWIL4 and TDRD1 genes determined by quantitative reverse transcription PCR.

Mentions: We further tightened the link between CpG island hypermethylation of the studied PIWI-class protein genes and transcriptional inactivation by the analyses of testicular cancer cell lines. Using a DNA methylation microarray14 that contains numerous CpG sites located in the PIWIL1, PIWIL2, PIWIL4, and TDRD1 CpG islands (Fig. 2), we found that the human testicular germ cell tumor lines 833K, GCT27 and SuSa showed dense promoter CpG island hypermethylation for the described genes. Most importantly, we did not observe expression of the four studied PIWI/piRNA pathway genes in any of the three studied cancer cell lines, while normal testis expressed the PIWIL1, PIWIL2, PIWIL4 and TDRD1 transcripts (Fig. 2).


Epigenetic loss of the PIWI/piRNA machinery in human testicular tumorigenesis.

Ferreira HJ, Heyn H, Garcia del Muro X, Vidal A, Larriba S, Muñoz C, Villanueva A, Esteller M - Epigenetics (2013)

Figure 2. Epigenetic inactivation of genes encoding piRNA-related proteins in testicular germ cell tumor lines. (A) DNA methylation levels at the 5′end CpG islands of the PIWIL1, PIWIL2, PIWIL4 and TDRD1 genes determined by sodium bisulfite modification coupled to hybridization to a DNA microarray (450K Illumina). DNA methylation levels are color-coded (red: high, green: low). Probe distances to the transcription start site (TSS) are indicated. (B) mRNA expression levels of the PIWIL1, PIWIL2, PIWIL4 and TDRD1 genes determined by quantitative reverse transcription PCR.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3928173&req=5

Figure 2: Figure 2. Epigenetic inactivation of genes encoding piRNA-related proteins in testicular germ cell tumor lines. (A) DNA methylation levels at the 5′end CpG islands of the PIWIL1, PIWIL2, PIWIL4 and TDRD1 genes determined by sodium bisulfite modification coupled to hybridization to a DNA microarray (450K Illumina). DNA methylation levels are color-coded (red: high, green: low). Probe distances to the transcription start site (TSS) are indicated. (B) mRNA expression levels of the PIWIL1, PIWIL2, PIWIL4 and TDRD1 genes determined by quantitative reverse transcription PCR.
Mentions: We further tightened the link between CpG island hypermethylation of the studied PIWI-class protein genes and transcriptional inactivation by the analyses of testicular cancer cell lines. Using a DNA methylation microarray14 that contains numerous CpG sites located in the PIWIL1, PIWIL2, PIWIL4, and TDRD1 CpG islands (Fig. 2), we found that the human testicular germ cell tumor lines 833K, GCT27 and SuSa showed dense promoter CpG island hypermethylation for the described genes. Most importantly, we did not observe expression of the four studied PIWI/piRNA pathway genes in any of the three studied cancer cell lines, while normal testis expressed the PIWIL1, PIWIL2, PIWIL4 and TDRD1 transcripts (Fig. 2).

Bottom Line: Although most cancer research has focused in mRNA, non-coding RNAs are also an essential player in tumorigenesis.Herein we have studied the putative existence of epigenetic aberrations in the activity of PIWI proteins, an Argonaute family protein subclass, and the small regulatory PIWI-interacting RNAs (piRNAs) in testicular cancer, as the PIWI/piRNA pathway plays a critical role in male germline development.We have observed the existence of promoter CpG island hypermethylation-associated silencing of PIWIL1, PIWIL2, PIWIL4, and TDRD1 in primary seminoma and non-seminoma testicular tumors, in addition to testicular germ cell tumor cell lines.

View Article: PubMed Central - PubMed

Affiliation: Cancer Epigenetics and Biology Program (PEBC); Bellvitge Biomedical Research Institute (IDIBELL); Barcelona, Spain; Programme in Experimental Biology and Biomedicine; Centre for Neurosciences and Cell Biology; University of Coimbra; Coimbra, Portugal.

ABSTRACT
Although most cancer research has focused in mRNA, non-coding RNAs are also an essential player in tumorigenesis. In addition to the well-recognized microRNAs, recent studies have also shown that epigenetic silencing by CpG island hypermethylation of other classes of non-coding RNAs, such as transcribed ultraconserved regions (T-UCRs) or small nucleolar RNAs (snoRNAs), also occur in human neoplasia. Herein we have studied the putative existence of epigenetic aberrations in the activity of PIWI proteins, an Argonaute family protein subclass, and the small regulatory PIWI-interacting RNAs (piRNAs) in testicular cancer, as the PIWI/piRNA pathway plays a critical role in male germline development. We have observed the existence of promoter CpG island hypermethylation-associated silencing of PIWIL1, PIWIL2, PIWIL4, and TDRD1 in primary seminoma and non-seminoma testicular tumors, in addition to testicular germ cell tumor cell lines. Most importantly, these epigenetic lesions occur in a context of piRNA downregulation and loss of DNA methylation of the LINE-1 repetitive sequences, one of the target genomic loci where the PIWI/piRNA machinery acts as a caretaker in non-transformed cells.

Show MeSH
Related in: MedlinePlus