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Zinc-finger protein 545 inhibits cell proliferation as a tumor suppressor through inducing apoptosis and is disrupted by promoter methylation in breast cancer.

Xiao Y, Xiang T, Luo X, Li C, Li Q, Peng W, Li L, Li S, Wang Z, Tang L, Ren G, Tao Q - PLoS ONE (2014)

Bottom Line: In this study, we found that ZNF545 was frequently downregulated in estrogen receptor-positive (ER+), progesterone receptor-positive (PR+) and human epidermal growth factor receptor 2-negative (HER2-) breast tumor tissues compared with paired adjacent non-tumor tissues.We found that ZNF545 was silenced by promoter methylation in MCF7 cell line, and its expression could be restored by demethylation, concomitant with increased unmethylated alleles.Taken together, these results demonstrate that ZNF545 inhibits breast tumor cell proliferation through inducing apoptosis and is disrupted by promoter methylation in breast cancer.

View Article: PubMed Central - PubMed

Affiliation: Molecular Oncology and Epigenetics Laboratory, The First Affiliated Hospital of Chongqing Medical University, Chongqing, China; Department of Endocrine and Breast Surgery, The First Affiliated Hospital of Chongqing Medical University, Chongqing, China.

ABSTRACT
Krüppel-associated box-containing zinc finger proteins (KRAP-ZFPs) are well recognized as key regulators of transcription, which play a crucial role in the regulation of cell proliferation, differentiation, apoptosis and tumorigenesis. We previously identified a KRAP-ZFP protein ZNF545 acting as a tumor suppressor involved in tumor pathogenesis. However, its expression and biological function in breast cancer remain elusive. In this study, we found that ZNF545 was frequently downregulated in estrogen receptor-positive (ER+), progesterone receptor-positive (PR+) and human epidermal growth factor receptor 2-negative (HER2-) breast tumor tissues compared with paired adjacent non-tumor tissues. We further examined its expression and methylation in breast cancer cell lines by semi-quantitative RT-PCR and methylation-specific PCR. We found that ZNF545 was silenced by promoter methylation in MCF7 cell line, and its expression could be restored by demethylation, concomitant with increased unmethylated alleles. ZNF545 methylation was detected in 29% of breast tumor tissues, but not in normal breast tissues, suggesting tumor-specific methylation of ZNF545 in breast cancer. Ectopic expression of ZNF545 in MCF7 cells inhibited cell proliferation through inducing cell cycle G0/G1 arrest and apoptosis, thus as a tumor suppressor. Moreover, ZNF545 upregulated mRNA and protein levels of c-Jun/AP1, BAX, p53 and Caspase 3. Taken together, these results demonstrate that ZNF545 inhibits breast tumor cell proliferation through inducing apoptosis and is disrupted by promoter methylation in breast cancer.

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Downregulation of ZNF545 in breast cancer.(A) ZNF545 expression in primary breast tumor tissues and paired surgical margin tissues were evaluated using quantitative RT-PCR analysis. (B) Reduced expression of ZNF545 in breast cancer. Data extracted from cancer microdatabase Oncomine: https://www.oncomine.org/. BN: Normal Breast tissues; IBC: Invasive Breast Carcinoma; LBC: lobular breast carcinoma. (C) ZNF545 expression by semi-quantitative RT-PCR and methylation status of the ZNF545 promoter by MSP in breast cancer cell lines. GAPDH was used as a control. (D) Pharmacological demethylation restores expression of ZNF545 in MCF7 cell treated with Aza combined with TSA (A+T), accompanied by demethylation of the promoter. M, methylated; U, unmethylated.
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pone-0110990-g001: Downregulation of ZNF545 in breast cancer.(A) ZNF545 expression in primary breast tumor tissues and paired surgical margin tissues were evaluated using quantitative RT-PCR analysis. (B) Reduced expression of ZNF545 in breast cancer. Data extracted from cancer microdatabase Oncomine: https://www.oncomine.org/. BN: Normal Breast tissues; IBC: Invasive Breast Carcinoma; LBC: lobular breast carcinoma. (C) ZNF545 expression by semi-quantitative RT-PCR and methylation status of the ZNF545 promoter by MSP in breast cancer cell lines. GAPDH was used as a control. (D) Pharmacological demethylation restores expression of ZNF545 in MCF7 cell treated with Aza combined with TSA (A+T), accompanied by demethylation of the promoter. M, methylated; U, unmethylated.

Mentions: We firstly examined ZNF545 expression in paired breast tumor tissues with different ER/PR/HER2 status by quantitative real-time PCR (qRT-PCR). We found that expression of ZNF545 was downregulated in 89.5% (17/19) of Luminal A (ER+/PR+/HER2−) subtypes, but increased in 69.2% (9/13) of triple negative (ER−/PR−/HER2−) and 87.5%(7/8) of Luminal B (ER+/PR+/HER2+) breast cancer tissues, compared with their adjacent non-tumor tissues (Fig. 1A, Table 2). We also detected ZNF545 expression in six breast cancer cell lines by semi-quantitative RT-PCR. Results showed that ZNF545 expression was silenced in MCF7 cells (Fig. 1C). Moreover, ZNF545 was significantly downregulated in breast cancer (Fig. 1B, Table 3), through analyzing the online microarray database (Oncomine, Compendia Bioscience, Ann Arbor, MI). These results suggest that ZNF545 is a candidate tumor suppressor for the Luminal A subtype breast cancer.


Zinc-finger protein 545 inhibits cell proliferation as a tumor suppressor through inducing apoptosis and is disrupted by promoter methylation in breast cancer.

Xiao Y, Xiang T, Luo X, Li C, Li Q, Peng W, Li L, Li S, Wang Z, Tang L, Ren G, Tao Q - PLoS ONE (2014)

Downregulation of ZNF545 in breast cancer.(A) ZNF545 expression in primary breast tumor tissues and paired surgical margin tissues were evaluated using quantitative RT-PCR analysis. (B) Reduced expression of ZNF545 in breast cancer. Data extracted from cancer microdatabase Oncomine: https://www.oncomine.org/. BN: Normal Breast tissues; IBC: Invasive Breast Carcinoma; LBC: lobular breast carcinoma. (C) ZNF545 expression by semi-quantitative RT-PCR and methylation status of the ZNF545 promoter by MSP in breast cancer cell lines. GAPDH was used as a control. (D) Pharmacological demethylation restores expression of ZNF545 in MCF7 cell treated with Aza combined with TSA (A+T), accompanied by demethylation of the promoter. M, methylated; U, unmethylated.
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Related In: Results  -  Collection

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getmorefigures.php?uid=PMC4215924&req=5

pone-0110990-g001: Downregulation of ZNF545 in breast cancer.(A) ZNF545 expression in primary breast tumor tissues and paired surgical margin tissues were evaluated using quantitative RT-PCR analysis. (B) Reduced expression of ZNF545 in breast cancer. Data extracted from cancer microdatabase Oncomine: https://www.oncomine.org/. BN: Normal Breast tissues; IBC: Invasive Breast Carcinoma; LBC: lobular breast carcinoma. (C) ZNF545 expression by semi-quantitative RT-PCR and methylation status of the ZNF545 promoter by MSP in breast cancer cell lines. GAPDH was used as a control. (D) Pharmacological demethylation restores expression of ZNF545 in MCF7 cell treated with Aza combined with TSA (A+T), accompanied by demethylation of the promoter. M, methylated; U, unmethylated.
Mentions: We firstly examined ZNF545 expression in paired breast tumor tissues with different ER/PR/HER2 status by quantitative real-time PCR (qRT-PCR). We found that expression of ZNF545 was downregulated in 89.5% (17/19) of Luminal A (ER+/PR+/HER2−) subtypes, but increased in 69.2% (9/13) of triple negative (ER−/PR−/HER2−) and 87.5%(7/8) of Luminal B (ER+/PR+/HER2+) breast cancer tissues, compared with their adjacent non-tumor tissues (Fig. 1A, Table 2). We also detected ZNF545 expression in six breast cancer cell lines by semi-quantitative RT-PCR. Results showed that ZNF545 expression was silenced in MCF7 cells (Fig. 1C). Moreover, ZNF545 was significantly downregulated in breast cancer (Fig. 1B, Table 3), through analyzing the online microarray database (Oncomine, Compendia Bioscience, Ann Arbor, MI). These results suggest that ZNF545 is a candidate tumor suppressor for the Luminal A subtype breast cancer.

Bottom Line: In this study, we found that ZNF545 was frequently downregulated in estrogen receptor-positive (ER+), progesterone receptor-positive (PR+) and human epidermal growth factor receptor 2-negative (HER2-) breast tumor tissues compared with paired adjacent non-tumor tissues.We found that ZNF545 was silenced by promoter methylation in MCF7 cell line, and its expression could be restored by demethylation, concomitant with increased unmethylated alleles.Taken together, these results demonstrate that ZNF545 inhibits breast tumor cell proliferation through inducing apoptosis and is disrupted by promoter methylation in breast cancer.

View Article: PubMed Central - PubMed

Affiliation: Molecular Oncology and Epigenetics Laboratory, The First Affiliated Hospital of Chongqing Medical University, Chongqing, China; Department of Endocrine and Breast Surgery, The First Affiliated Hospital of Chongqing Medical University, Chongqing, China.

ABSTRACT
Krüppel-associated box-containing zinc finger proteins (KRAP-ZFPs) are well recognized as key regulators of transcription, which play a crucial role in the regulation of cell proliferation, differentiation, apoptosis and tumorigenesis. We previously identified a KRAP-ZFP protein ZNF545 acting as a tumor suppressor involved in tumor pathogenesis. However, its expression and biological function in breast cancer remain elusive. In this study, we found that ZNF545 was frequently downregulated in estrogen receptor-positive (ER+), progesterone receptor-positive (PR+) and human epidermal growth factor receptor 2-negative (HER2-) breast tumor tissues compared with paired adjacent non-tumor tissues. We further examined its expression and methylation in breast cancer cell lines by semi-quantitative RT-PCR and methylation-specific PCR. We found that ZNF545 was silenced by promoter methylation in MCF7 cell line, and its expression could be restored by demethylation, concomitant with increased unmethylated alleles. ZNF545 methylation was detected in 29% of breast tumor tissues, but not in normal breast tissues, suggesting tumor-specific methylation of ZNF545 in breast cancer. Ectopic expression of ZNF545 in MCF7 cells inhibited cell proliferation through inducing cell cycle G0/G1 arrest and apoptosis, thus as a tumor suppressor. Moreover, ZNF545 upregulated mRNA and protein levels of c-Jun/AP1, BAX, p53 and Caspase 3. Taken together, these results demonstrate that ZNF545 inhibits breast tumor cell proliferation through inducing apoptosis and is disrupted by promoter methylation in breast cancer.

Show MeSH
Related in: MedlinePlus