RUNX3 is frequently inactivated by dual mechanisms of protein mislocalization and promoter hypermethylation in breast cancer

Quek Choon Lau, Erna Raja, Manuel Salto-Tellez, Qiang Liu, Kosei Ito, Masafumi Inoue, Thomas Choudary Putti, Marie Loh, Tun Kiat Ko, Canhua Huang, Kapil N. Bhalla, Tao Zhu, Yoshiaki Ito, Saraswati Sukumar

Research output: Contribution to journalArticle

Abstract

A tumor suppressor function has been attributed to RUNX3, a member of the RUNX family of transcription factors. Here, we examined alterations in the expression of three members, RUNX1, RUNX2, and RUNX3, and their interacting partner, CBF-β, in breast cancer. Among them, RUNX3 was consistently underexpressed in breast cancer cell lines and primary tumors. Fifty percent of the breast cancer cell lines (n = 19) showed hypermethylation at the promoter region and displayed significantly lower levels of RUNX3 mRNA expression (P <0.0001) and protein (P <0.001). In primary Singaporean breast cancers, 9 of 44 specimens showed undetectable levels of RUNX3 by immunohistochemistry. In 35 of 44 tumors, however, low levels of RUNX3 protein were present. Remarkably, in each case, protein was mislocalized to the cytoplasm. In primary tumors, hypermethylation of RUNX3 was observed in 23 of 44 cases (52%) and was undetectable in matched adjacent normal breast epithelium. Mislocalization of the protein, with or without methylation, seems to account for RUNX3 inactivation in the vast majority of the tumors. In in vitro and in vivo assays, RUNX3 behaved as a growth suppressor in breast cancer cells. Stable expression of RUNX3 in MDA-MB-231 breast cancer cells led to a more cuboidal phenotype, significantly reduced invasiveness in Matrigel invasion assays, and suppressed tumor formation in immunodeficient mice. This study provides biological and mechanistic insights into RUNX3 as the key member of the family that plays a role in breast cancer. Frequent protein mislocalization and methylation could render RUNX3 a valuable marker for early detection and risk assessment.

Original languageEnglish (US)
Pages (from-to)6512-6520
Number of pages9
JournalCancer Research
Volume66
Issue number13
DOIs
StatePublished - Jul 1 2006

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Breast Neoplasms
Proteins
Neoplasms
Methylation
Tumor Cell Line
Genetic Promoter Regions
Cytoplasm
Breast
Transcription Factors
Epithelium
Immunohistochemistry
Phenotype
Cell Line
Messenger RNA
Growth

ASJC Scopus subject areas

  • Cancer Research
  • Oncology

Cite this

RUNX3 is frequently inactivated by dual mechanisms of protein mislocalization and promoter hypermethylation in breast cancer. / Lau, Quek Choon; Raja, Erna; Salto-Tellez, Manuel; Liu, Qiang; Ito, Kosei; Inoue, Masafumi; Putti, Thomas Choudary; Loh, Marie; Ko, Tun Kiat; Huang, Canhua; Bhalla, Kapil N.; Zhu, Tao; Ito, Yoshiaki; Sukumar, Saraswati.

In: Cancer Research, Vol. 66, No. 13, 01.07.2006, p. 6512-6520.

Research output: Contribution to journalArticle

Lau, QC, Raja, E, Salto-Tellez, M, Liu, Q, Ito, K, Inoue, M, Putti, TC, Loh, M, Ko, TK, Huang, C, Bhalla, KN, Zhu, T, Ito, Y & Sukumar, S 2006, 'RUNX3 is frequently inactivated by dual mechanisms of protein mislocalization and promoter hypermethylation in breast cancer', Cancer Research, vol. 66, no. 13, pp. 6512-6520. https://doi.org/10.1158/0008-5472.CAN-06-0369
Lau, Quek Choon ; Raja, Erna ; Salto-Tellez, Manuel ; Liu, Qiang ; Ito, Kosei ; Inoue, Masafumi ; Putti, Thomas Choudary ; Loh, Marie ; Ko, Tun Kiat ; Huang, Canhua ; Bhalla, Kapil N. ; Zhu, Tao ; Ito, Yoshiaki ; Sukumar, Saraswati. / RUNX3 is frequently inactivated by dual mechanisms of protein mislocalization and promoter hypermethylation in breast cancer. In: Cancer Research. 2006 ; Vol. 66, No. 13. pp. 6512-6520.
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abstract = "A tumor suppressor function has been attributed to RUNX3, a member of the RUNX family of transcription factors. Here, we examined alterations in the expression of three members, RUNX1, RUNX2, and RUNX3, and their interacting partner, CBF-β, in breast cancer. Among them, RUNX3 was consistently underexpressed in breast cancer cell lines and primary tumors. Fifty percent of the breast cancer cell lines (n = 19) showed hypermethylation at the promoter region and displayed significantly lower levels of RUNX3 mRNA expression (P <0.0001) and protein (P <0.001). In primary Singaporean breast cancers, 9 of 44 specimens showed undetectable levels of RUNX3 by immunohistochemistry. In 35 of 44 tumors, however, low levels of RUNX3 protein were present. Remarkably, in each case, protein was mislocalized to the cytoplasm. In primary tumors, hypermethylation of RUNX3 was observed in 23 of 44 cases (52{\%}) and was undetectable in matched adjacent normal breast epithelium. Mislocalization of the protein, with or without methylation, seems to account for RUNX3 inactivation in the vast majority of the tumors. In in vitro and in vivo assays, RUNX3 behaved as a growth suppressor in breast cancer cells. Stable expression of RUNX3 in MDA-MB-231 breast cancer cells led to a more cuboidal phenotype, significantly reduced invasiveness in Matrigel invasion assays, and suppressed tumor formation in immunodeficient mice. This study provides biological and mechanistic insights into RUNX3 as the key member of the family that plays a role in breast cancer. Frequent protein mislocalization and methylation could render RUNX3 a valuable marker for early detection and risk assessment.",
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AU - Lau, Quek Choon

AU - Raja, Erna

AU - Salto-Tellez, Manuel

AU - Liu, Qiang

AU - Ito, Kosei

AU - Inoue, Masafumi

AU - Putti, Thomas Choudary

AU - Loh, Marie

AU - Ko, Tun Kiat

AU - Huang, Canhua

AU - Bhalla, Kapil N.

AU - Zhu, Tao

AU - Ito, Yoshiaki

AU - Sukumar, Saraswati

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N2 - A tumor suppressor function has been attributed to RUNX3, a member of the RUNX family of transcription factors. Here, we examined alterations in the expression of three members, RUNX1, RUNX2, and RUNX3, and their interacting partner, CBF-β, in breast cancer. Among them, RUNX3 was consistently underexpressed in breast cancer cell lines and primary tumors. Fifty percent of the breast cancer cell lines (n = 19) showed hypermethylation at the promoter region and displayed significantly lower levels of RUNX3 mRNA expression (P <0.0001) and protein (P <0.001). In primary Singaporean breast cancers, 9 of 44 specimens showed undetectable levels of RUNX3 by immunohistochemistry. In 35 of 44 tumors, however, low levels of RUNX3 protein were present. Remarkably, in each case, protein was mislocalized to the cytoplasm. In primary tumors, hypermethylation of RUNX3 was observed in 23 of 44 cases (52%) and was undetectable in matched adjacent normal breast epithelium. Mislocalization of the protein, with or without methylation, seems to account for RUNX3 inactivation in the vast majority of the tumors. In in vitro and in vivo assays, RUNX3 behaved as a growth suppressor in breast cancer cells. Stable expression of RUNX3 in MDA-MB-231 breast cancer cells led to a more cuboidal phenotype, significantly reduced invasiveness in Matrigel invasion assays, and suppressed tumor formation in immunodeficient mice. This study provides biological and mechanistic insights into RUNX3 as the key member of the family that plays a role in breast cancer. Frequent protein mislocalization and methylation could render RUNX3 a valuable marker for early detection and risk assessment.

AB - A tumor suppressor function has been attributed to RUNX3, a member of the RUNX family of transcription factors. Here, we examined alterations in the expression of three members, RUNX1, RUNX2, and RUNX3, and their interacting partner, CBF-β, in breast cancer. Among them, RUNX3 was consistently underexpressed in breast cancer cell lines and primary tumors. Fifty percent of the breast cancer cell lines (n = 19) showed hypermethylation at the promoter region and displayed significantly lower levels of RUNX3 mRNA expression (P <0.0001) and protein (P <0.001). In primary Singaporean breast cancers, 9 of 44 specimens showed undetectable levels of RUNX3 by immunohistochemistry. In 35 of 44 tumors, however, low levels of RUNX3 protein were present. Remarkably, in each case, protein was mislocalized to the cytoplasm. In primary tumors, hypermethylation of RUNX3 was observed in 23 of 44 cases (52%) and was undetectable in matched adjacent normal breast epithelium. Mislocalization of the protein, with or without methylation, seems to account for RUNX3 inactivation in the vast majority of the tumors. In in vitro and in vivo assays, RUNX3 behaved as a growth suppressor in breast cancer cells. Stable expression of RUNX3 in MDA-MB-231 breast cancer cells led to a more cuboidal phenotype, significantly reduced invasiveness in Matrigel invasion assays, and suppressed tumor formation in immunodeficient mice. This study provides biological and mechanistic insights into RUNX3 as the key member of the family that plays a role in breast cancer. Frequent protein mislocalization and methylation could render RUNX3 a valuable marker for early detection and risk assessment.

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