Down-regulation of tumor suppressor a kinase anchor protein 12 in human hepatocarcinogenesis by epigenetic mechanisms

Benjamin Goeppert; Peter Schmezer; Céline Dutruel; Christopher Oakes; Marcus Renner; Marco Breinig; Arne Warth; Monika Nadja Vogel; Michel Mittelbronn; Arianeb Mehrabi; Georg Gdynia; Roland Penzel; Thomas Longerich; Kai Breuhahn; Odilia Popanda; Christoph Plass; Peter Schirmacher; Michael André Kern

doi:10.1002/hep.23939

Down-regulation of tumor suppressor a kinase anchor protein 12 in human hepatocarcinogenesis by epigenetic mechanisms

Benjamin Goeppert^*, Peter Schmezer, Céline Dutruel, Christopher Oakes, Marcus Renner, Marco Breinig, Arne Warth, Monika Nadja Vogel, Michel Mittelbronn, Arianeb Mehrabi, Georg Gdynia, Roland Penzel, Thomas Longerich, Kai Breuhahn, Odilia Popanda, Christoph Plass, Peter Schirmacher, Michael André Kern

^*Corresponding author for this work

Research output: Contribution to journal › Article › Research › peer-review

64 Citations (Scopus)

Abstract

The A kinase anchor protein 12 (AKAP12) is a central mediator of protein kinase A and protein kinase C signaling. Although AKAP12 has been described to act as a tumor suppressor and its expression is frequently down-regulated in several human malignancies, the underlying molecular mechanisms responsible for the AKAP12 reduction are poorly understood. We therefore analyzed the expression of AKAP12 and its genetic and epigenetic regulatory mechanisms in human hepatocarcinogenesis. Based on tissue microarray analyses (n = 388) and western immunoblotting, we observed a significant reduction of AKAP12 in cirrhotic liver (CL), premalignant lesions (DN), and hepatocellular carcinomas (HCCs) compared to histologically normal liver specimens (NL). Analyses of array comparative genomic hybridization data (aCGH) from human HCCs revealed chromosomal losses of AKAP12 in 36% of cases but suggested additional mechanisms underlying the observed reduction of AKAP12 expression in hepatocarcinogenesis. Quantitative methylation analysis by MassARRAY of NL, CL, DN, and HCC tissues, as well as of various tumorigenic and nontumorigenic liver cell lines revealed specific hypermethylation of the AKAP12α promoter but not of the AKAP12β promoter in HCC specimens and in HCC cell lines. Consequently, restoration experiments performed with 5-aza-2'deoxycytidine drastically increased AKAP12α mRNA levels in a HCC cell line (AKN1) paralleled by AKAP12α promoter demethylation. As hypermethylation is not observed in CL and DN, we investigated microRNA-mediated posttranscriptional regulation as an additional mechanism to explain reduced AKAP12 expression. We found that miR-183 and miR-186 are up-regulated in CL and DN and are able to target AKAP12. Conclusion: In addition to genetic alterations, epigenetic mechanisms are responsible for the reduction of the tumor suppressor gene AKAP12 in human hepatocarcinogenesis.

Original language	English
Pages (from-to)	2023-2033
Number of pages	11
Journal	Hepatology
Volume	52
Issue number	6
DOIs	https://doi.org/10.1002/hep.23939
Publication status	Published - Dec 2010
Externally published	Yes

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10.1002/hep.23939

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Goeppert, B., Schmezer, P., Dutruel, C., Oakes, C., Renner, M., Breinig, M., Warth, A., Vogel, M. N., Mittelbronn, M., Mehrabi, A., Gdynia, G., Penzel, R., Longerich, T., Breuhahn, K., Popanda, O., Plass, C., Schirmacher, P., & Kern, M. A. (2010). Down-regulation of tumor suppressor a kinase anchor protein 12 in human hepatocarcinogenesis by epigenetic mechanisms. Hepatology, 52(6), 2023-2033. https://doi.org/10.1002/hep.23939

@article{bf5a625140fc4794941c411d0f936ed4,

title = "Down-regulation of tumor suppressor a kinase anchor protein 12 in human hepatocarcinogenesis by epigenetic mechanisms",

abstract = "The A kinase anchor protein 12 (AKAP12) is a central mediator of protein kinase A and protein kinase C signaling. Although AKAP12 has been described to act as a tumor suppressor and its expression is frequently down-regulated in several human malignancies, the underlying molecular mechanisms responsible for the AKAP12 reduction are poorly understood. We therefore analyzed the expression of AKAP12 and its genetic and epigenetic regulatory mechanisms in human hepatocarcinogenesis. Based on tissue microarray analyses (n = 388) and western immunoblotting, we observed a significant reduction of AKAP12 in cirrhotic liver (CL), premalignant lesions (DN), and hepatocellular carcinomas (HCCs) compared to histologically normal liver specimens (NL). Analyses of array comparative genomic hybridization data (aCGH) from human HCCs revealed chromosomal losses of AKAP12 in 36% of cases but suggested additional mechanisms underlying the observed reduction of AKAP12 expression in hepatocarcinogenesis. Quantitative methylation analysis by MassARRAY of NL, CL, DN, and HCC tissues, as well as of various tumorigenic and nontumorigenic liver cell lines revealed specific hypermethylation of the AKAP12α promoter but not of the AKAP12β promoter in HCC specimens and in HCC cell lines. Consequently, restoration experiments performed with 5-aza-2'deoxycytidine drastically increased AKAP12α mRNA levels in a HCC cell line (AKN1) paralleled by AKAP12α promoter demethylation. As hypermethylation is not observed in CL and DN, we investigated microRNA-mediated posttranscriptional regulation as an additional mechanism to explain reduced AKAP12 expression. We found that miR-183 and miR-186 are up-regulated in CL and DN and are able to target AKAP12. Conclusion: In addition to genetic alterations, epigenetic mechanisms are responsible for the reduction of the tumor suppressor gene AKAP12 in human hepatocarcinogenesis.",

author = "Benjamin Goeppert and Peter Schmezer and C{\'e}line Dutruel and Christopher Oakes and Marcus Renner and Marco Breinig and Arne Warth and Vogel, {Monika Nadja} and Michel Mittelbronn and Arianeb Mehrabi and Georg Gdynia and Roland Penzel and Thomas Longerich and Kai Breuhahn and Odilia Popanda and Christoph Plass and Peter Schirmacher and Kern, {Michael Andr{\'e}}",

year = "2010",

month = dec,

doi = "10.1002/hep.23939",

language = "English",

volume = "52",

pages = "2023--2033",

journal = "Hepatology",

issn = "0270-9139",

publisher = "John Wiley and Sons Ltd",

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Goeppert, B, Schmezer, P, Dutruel, C, Oakes, C, Renner, M, Breinig, M, Warth, A, Vogel, MN, Mittelbronn, M, Mehrabi, A, Gdynia, G, Penzel, R, Longerich, T, Breuhahn, K, Popanda, O, Plass, C, Schirmacher, P & Kern, MA 2010, 'Down-regulation of tumor suppressor a kinase anchor protein 12 in human hepatocarcinogenesis by epigenetic mechanisms', Hepatology, vol. 52, no. 6, pp. 2023-2033. https://doi.org/10.1002/hep.23939

TY - JOUR

T1 - Down-regulation of tumor suppressor a kinase anchor protein 12 in human hepatocarcinogenesis by epigenetic mechanisms

AU - Goeppert, Benjamin

AU - Schmezer, Peter

AU - Dutruel, Céline

AU - Oakes, Christopher

AU - Renner, Marcus

AU - Breinig, Marco

AU - Warth, Arne

AU - Vogel, Monika Nadja

AU - Mittelbronn, Michel

AU - Mehrabi, Arianeb

AU - Gdynia, Georg

AU - Penzel, Roland

AU - Longerich, Thomas

AU - Breuhahn, Kai

AU - Popanda, Odilia

AU - Plass, Christoph

AU - Schirmacher, Peter

AU - Kern, Michael André

PY - 2010/12

Y1 - 2010/12

N2 - The A kinase anchor protein 12 (AKAP12) is a central mediator of protein kinase A and protein kinase C signaling. Although AKAP12 has been described to act as a tumor suppressor and its expression is frequently down-regulated in several human malignancies, the underlying molecular mechanisms responsible for the AKAP12 reduction are poorly understood. We therefore analyzed the expression of AKAP12 and its genetic and epigenetic regulatory mechanisms in human hepatocarcinogenesis. Based on tissue microarray analyses (n = 388) and western immunoblotting, we observed a significant reduction of AKAP12 in cirrhotic liver (CL), premalignant lesions (DN), and hepatocellular carcinomas (HCCs) compared to histologically normal liver specimens (NL). Analyses of array comparative genomic hybridization data (aCGH) from human HCCs revealed chromosomal losses of AKAP12 in 36% of cases but suggested additional mechanisms underlying the observed reduction of AKAP12 expression in hepatocarcinogenesis. Quantitative methylation analysis by MassARRAY of NL, CL, DN, and HCC tissues, as well as of various tumorigenic and nontumorigenic liver cell lines revealed specific hypermethylation of the AKAP12α promoter but not of the AKAP12β promoter in HCC specimens and in HCC cell lines. Consequently, restoration experiments performed with 5-aza-2'deoxycytidine drastically increased AKAP12α mRNA levels in a HCC cell line (AKN1) paralleled by AKAP12α promoter demethylation. As hypermethylation is not observed in CL and DN, we investigated microRNA-mediated posttranscriptional regulation as an additional mechanism to explain reduced AKAP12 expression. We found that miR-183 and miR-186 are up-regulated in CL and DN and are able to target AKAP12. Conclusion: In addition to genetic alterations, epigenetic mechanisms are responsible for the reduction of the tumor suppressor gene AKAP12 in human hepatocarcinogenesis.

AB - The A kinase anchor protein 12 (AKAP12) is a central mediator of protein kinase A and protein kinase C signaling. Although AKAP12 has been described to act as a tumor suppressor and its expression is frequently down-regulated in several human malignancies, the underlying molecular mechanisms responsible for the AKAP12 reduction are poorly understood. We therefore analyzed the expression of AKAP12 and its genetic and epigenetic regulatory mechanisms in human hepatocarcinogenesis. Based on tissue microarray analyses (n = 388) and western immunoblotting, we observed a significant reduction of AKAP12 in cirrhotic liver (CL), premalignant lesions (DN), and hepatocellular carcinomas (HCCs) compared to histologically normal liver specimens (NL). Analyses of array comparative genomic hybridization data (aCGH) from human HCCs revealed chromosomal losses of AKAP12 in 36% of cases but suggested additional mechanisms underlying the observed reduction of AKAP12 expression in hepatocarcinogenesis. Quantitative methylation analysis by MassARRAY of NL, CL, DN, and HCC tissues, as well as of various tumorigenic and nontumorigenic liver cell lines revealed specific hypermethylation of the AKAP12α promoter but not of the AKAP12β promoter in HCC specimens and in HCC cell lines. Consequently, restoration experiments performed with 5-aza-2'deoxycytidine drastically increased AKAP12α mRNA levels in a HCC cell line (AKN1) paralleled by AKAP12α promoter demethylation. As hypermethylation is not observed in CL and DN, we investigated microRNA-mediated posttranscriptional regulation as an additional mechanism to explain reduced AKAP12 expression. We found that miR-183 and miR-186 are up-regulated in CL and DN and are able to target AKAP12. Conclusion: In addition to genetic alterations, epigenetic mechanisms are responsible for the reduction of the tumor suppressor gene AKAP12 in human hepatocarcinogenesis.

UR - http://www.scopus.com/inward/record.url?scp=78649613036&partnerID=8YFLogxK

U2 - 10.1002/hep.23939

DO - 10.1002/hep.23939

M3 - Article

C2 - 20979053

AN - SCOPUS:78649613036

SN - 0270-9139

VL - 52

SP - 2023

EP - 2033

JO - Hepatology

JF - Hepatology

IS - 6

ER -

Down-regulation of tumor suppressor a kinase anchor protein 12 in human hepatocarcinogenesis by epigenetic mechanisms

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