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The apoptosis associated tyrosine kinase gene is frequently hypermethylated in human cancer and is regulated by epigenetic mechanisms.

Haag T, Herkt CE, Walesch SK, Richter AM, Dammann RH - Genes Cancer (2014)

Bottom Line: Epigenetic gene inactivation through promoter hypermethylation is an important aberration involved in the silencing of tumor-associated genes in cancer.Aberrant methylation of AATK was also revealed in primary lung (40%) and breast (53%) cancers, but was found to be significantly less methylated in matching normal breast tissues (17%; p<0.01).We further show that overexpression of Aatk significantly suppresses colony formation in cancer cell lines.

View Article: PubMed Central - PubMed

Affiliation: Institute for Genetics; Justus-Liebig-University; Universities of Giessen and Marburg Lung Center, Member of the German Center for Lung Research; Giessen, Germany.

ABSTRACT
Epigenetic gene inactivation through promoter hypermethylation is an important aberration involved in the silencing of tumor-associated genes in cancer. Here we identified the apoptosis associated tyrosine kinase (AATK) as an epigenetically downregulated tumor related gene. We analyzed the epigenetic regulation of AATK in several human cancer cell lines and normal tissues by methylation and expression analysis. Hypermethylation of AATK was also analyzed in 25 primary lung tumors, 30 breast cancers and 24 matching breast tissues. In normal tissues the AATK CpG island promoter was unmethylated and AATK was expressed. Hypermethylation of AATK occurred frequently in 13 out of 14 (93%) human cancer cell lines. Methylation was reversed by 5-aza-2'-deoxycytidine treatment leading to re-expression of AATK in cancer cell lines. Aberrant methylation of AATK was also revealed in primary lung (40%) and breast (53%) cancers, but was found to be significantly less methylated in matching normal breast tissues (17%; p<0.01). In addition, we observed that AATK is epigenetically reactivated through the chromatin regulator CTCF. We further show that overexpression of Aatk significantly suppresses colony formation in cancer cell lines. Our findings suggest that the apoptosis associated tyrosine kinase is frequently inactivated in human cancers and acts as a tumor suppressive gene.

No MeSH data available.


Related in: MedlinePlus

Hypermethylation of AATK in human cancersA. Structure of the AATK CpG island promoter on chromosome 17 and the AATK protein. Arrows mark transcriptional (+1) start site for AATK. Vertical lines indicate CpGs. The 111 bp PCR product with respective primers and the TaqI site are depicted. The CTCF binding site is shown. The protein tyrosine kinase (PTK domain) of AATK is marked. B. Combined bisulfite restriction analysis of AATK. Bisulfite-treated DNA from the indicated cancer cell lines, human fibroblasts (HF-55) and in vitro methylated DNA (i.v.m.) was amplified, digested with TaqI (+) or mock digested (−) and resolved on 2% gels with a 100 bp marker (M). C. Bisulfite pyrosequence analysis of AATK. The methylation levels of three CpGs of the PCR products were analyzed by pyrosequencing.
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Figure 1: Hypermethylation of AATK in human cancersA. Structure of the AATK CpG island promoter on chromosome 17 and the AATK protein. Arrows mark transcriptional (+1) start site for AATK. Vertical lines indicate CpGs. The 111 bp PCR product with respective primers and the TaqI site are depicted. The CTCF binding site is shown. The protein tyrosine kinase (PTK domain) of AATK is marked. B. Combined bisulfite restriction analysis of AATK. Bisulfite-treated DNA from the indicated cancer cell lines, human fibroblasts (HF-55) and in vitro methylated DNA (i.v.m.) was amplified, digested with TaqI (+) or mock digested (−) and resolved on 2% gels with a 100 bp marker (M). C. Bisulfite pyrosequence analysis of AATK. The methylation levels of three CpGs of the PCR products were analyzed by pyrosequencing.

Mentions: The apoptosis associated tyrosine kinase (AATK) gene is localized on chromosome 17 at q25.3 [13]. Deletion of 17q25.3 was reported for several human cancers including oral, cervical and breast cancer [14-16]. The AATK protein that is also named AATYK or LMTK1 (lemur tyrosine kinase 1) consists of 1374 aa with the N-terminus harboring a protein tyrosine kinase domain (Fig. 1) [17]. AATK promotes neuronal differentiation and is induced during growth arrest and apoptosis of myeloid cells [18, 19]. Downregulation of AATK expression was reported for adenocarcinoma of the colon and for melanomas [20, 21]. In melanoma cells AATK overexpression inhibits growth and migration, and promotes apoptosis [21]. In our study we report frequent epigenetic inactivation of AATK in different human cancer entities (e.g. breast and lung) and its growth suppressive function in lung cancer. Furthermore, we show that the chromatin regulator CTCF induces epigenetic reactivation of AATK.


The apoptosis associated tyrosine kinase gene is frequently hypermethylated in human cancer and is regulated by epigenetic mechanisms.

Haag T, Herkt CE, Walesch SK, Richter AM, Dammann RH - Genes Cancer (2014)

Hypermethylation of AATK in human cancersA. Structure of the AATK CpG island promoter on chromosome 17 and the AATK protein. Arrows mark transcriptional (+1) start site for AATK. Vertical lines indicate CpGs. The 111 bp PCR product with respective primers and the TaqI site are depicted. The CTCF binding site is shown. The protein tyrosine kinase (PTK domain) of AATK is marked. B. Combined bisulfite restriction analysis of AATK. Bisulfite-treated DNA from the indicated cancer cell lines, human fibroblasts (HF-55) and in vitro methylated DNA (i.v.m.) was amplified, digested with TaqI (+) or mock digested (−) and resolved on 2% gels with a 100 bp marker (M). C. Bisulfite pyrosequence analysis of AATK. The methylation levels of three CpGs of the PCR products were analyzed by pyrosequencing.
© Copyright Policy - open-access
Related In: Results  -  Collection

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Show All Figures
getmorefigures.php?uid=PMC4209602&req=5

Figure 1: Hypermethylation of AATK in human cancersA. Structure of the AATK CpG island promoter on chromosome 17 and the AATK protein. Arrows mark transcriptional (+1) start site for AATK. Vertical lines indicate CpGs. The 111 bp PCR product with respective primers and the TaqI site are depicted. The CTCF binding site is shown. The protein tyrosine kinase (PTK domain) of AATK is marked. B. Combined bisulfite restriction analysis of AATK. Bisulfite-treated DNA from the indicated cancer cell lines, human fibroblasts (HF-55) and in vitro methylated DNA (i.v.m.) was amplified, digested with TaqI (+) or mock digested (−) and resolved on 2% gels with a 100 bp marker (M). C. Bisulfite pyrosequence analysis of AATK. The methylation levels of three CpGs of the PCR products were analyzed by pyrosequencing.
Mentions: The apoptosis associated tyrosine kinase (AATK) gene is localized on chromosome 17 at q25.3 [13]. Deletion of 17q25.3 was reported for several human cancers including oral, cervical and breast cancer [14-16]. The AATK protein that is also named AATYK or LMTK1 (lemur tyrosine kinase 1) consists of 1374 aa with the N-terminus harboring a protein tyrosine kinase domain (Fig. 1) [17]. AATK promotes neuronal differentiation and is induced during growth arrest and apoptosis of myeloid cells [18, 19]. Downregulation of AATK expression was reported for adenocarcinoma of the colon and for melanomas [20, 21]. In melanoma cells AATK overexpression inhibits growth and migration, and promotes apoptosis [21]. In our study we report frequent epigenetic inactivation of AATK in different human cancer entities (e.g. breast and lung) and its growth suppressive function in lung cancer. Furthermore, we show that the chromatin regulator CTCF induces epigenetic reactivation of AATK.

Bottom Line: Epigenetic gene inactivation through promoter hypermethylation is an important aberration involved in the silencing of tumor-associated genes in cancer.Aberrant methylation of AATK was also revealed in primary lung (40%) and breast (53%) cancers, but was found to be significantly less methylated in matching normal breast tissues (17%; p<0.01).We further show that overexpression of Aatk significantly suppresses colony formation in cancer cell lines.

View Article: PubMed Central - PubMed

Affiliation: Institute for Genetics; Justus-Liebig-University; Universities of Giessen and Marburg Lung Center, Member of the German Center for Lung Research; Giessen, Germany.

ABSTRACT
Epigenetic gene inactivation through promoter hypermethylation is an important aberration involved in the silencing of tumor-associated genes in cancer. Here we identified the apoptosis associated tyrosine kinase (AATK) as an epigenetically downregulated tumor related gene. We analyzed the epigenetic regulation of AATK in several human cancer cell lines and normal tissues by methylation and expression analysis. Hypermethylation of AATK was also analyzed in 25 primary lung tumors, 30 breast cancers and 24 matching breast tissues. In normal tissues the AATK CpG island promoter was unmethylated and AATK was expressed. Hypermethylation of AATK occurred frequently in 13 out of 14 (93%) human cancer cell lines. Methylation was reversed by 5-aza-2'-deoxycytidine treatment leading to re-expression of AATK in cancer cell lines. Aberrant methylation of AATK was also revealed in primary lung (40%) and breast (53%) cancers, but was found to be significantly less methylated in matching normal breast tissues (17%; p<0.01). In addition, we observed that AATK is epigenetically reactivated through the chromatin regulator CTCF. We further show that overexpression of Aatk significantly suppresses colony formation in cancer cell lines. Our findings suggest that the apoptosis associated tyrosine kinase is frequently inactivated in human cancers and acts as a tumor suppressive gene.

No MeSH data available.


Related in: MedlinePlus