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OPCML is a broad tumor suppressor for multiple carcinomas and lymphomas with frequently epigenetic inactivation.

Cui Y, Ying Y, van Hasselt A, Ng KM, Yu J, Zhang Q, Jin J, Liu D, Rhim JS, Rha SY, Loyo M, Chan AT, Srivastava G, Tsao GS, Sellar GC, Sung JJ, Sidransky D, Tao Q - PLoS ONE (2008)

Bottom Line: Pharmacological and genetic demethylation restored OPCML expression, indicating a direct epigenetic silencing.We further found that OPCML is stress-responsive, but this response is epigenetically impaired when its promoter becomes methylated.Ecotopic expression of OPCML led to significant inhibition of both anchorage-dependent and -independent growth of carcinoma cells with endogenous silencing.

View Article: PubMed Central - PubMed

Affiliation: State Key Laboratory in Oncology in South China, Sir YK Pao Center for Cancer, Department of Clinical Oncology, Hong Kong Cancer Institute, Chinese University of Hong Kong, Hong Kong, China.

ABSTRACT

Background: Identification of tumor suppressor genes (TSGs) silenced by CpG methylation uncovers the molecular mechanism of tumorigenesis and potential tumor biomarkers. Loss of heterozygosity at 11q25 is common in multiple tumors including nasopharyngeal carcinoma (NPC). OPCML, located at 11q25, is one of the downregulated genes we identified through digital expression subtraction.

Methodology/principal findings: Semi-quantitative RT-PCR showed frequent OPCML silencing in NPC and other common tumors, with no homozygous deletion detected by multiplex differential DNA-PCR. Instead, promoter methylation of OPCML was frequently detected in multiple carcinoma cell lines (nasopharyngeal, esophageal, lung, gastric, colon, liver, breast, cervix, prostate), lymphoma cell lines (non-Hodgkin and Hodgkin lymphoma, nasal NK/T-cell lymphoma) and primary tumors, but not in any non-tumor cell line and seldom weakly methylated in normal epithelial tissues. Pharmacological and genetic demethylation restored OPCML expression, indicating a direct epigenetic silencing. We further found that OPCML is stress-responsive, but this response is epigenetically impaired when its promoter becomes methylated. Ecotopic expression of OPCML led to significant inhibition of both anchorage-dependent and -independent growth of carcinoma cells with endogenous silencing.

Conclusions/significance: Thus, through functional epigenetics, we identified OPCML as a broad tumor suppressor, which is frequently inactivated by methylation in multiple malignancies.

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The OPCML-v1 promoter is stress- and p53-responsive.(A) Locations of transcription factors (HSF, p53, Sp1, E2F, STAT) binding sites in the promoter are indicated. (B) Up-regulation of OPCML-v1 in response to stress treatments is disrupted in tumor cell lines with a methylated promoter. Normal (NE3, HEK293, NE1) and tumor cell lines (Rael, CNE1, C666-1, HK1) were exposed to 42°C heat shock (HS), UV irradiation, or H2O2 treatments. OPCML-v1 promoter methylation status in each cell line is shown at the bottom. M, methylated; U, unmethylated. (C) H1299 cells were transfected with different amounts of pcDNA3.1+/TP53 (gift from Dr. Bert Vogelstein) [27]. Expression of OPCML-v1 and v2 was analyzed by semi-quantitative RT-PCR. p53 induced a dosage-dependent upregulation of OPCML-v1.
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pone-0002990-g007: The OPCML-v1 promoter is stress- and p53-responsive.(A) Locations of transcription factors (HSF, p53, Sp1, E2F, STAT) binding sites in the promoter are indicated. (B) Up-regulation of OPCML-v1 in response to stress treatments is disrupted in tumor cell lines with a methylated promoter. Normal (NE3, HEK293, NE1) and tumor cell lines (Rael, CNE1, C666-1, HK1) were exposed to 42°C heat shock (HS), UV irradiation, or H2O2 treatments. OPCML-v1 promoter methylation status in each cell line is shown at the bottom. M, methylated; U, unmethylated. (C) H1299 cells were transfected with different amounts of pcDNA3.1+/TP53 (gift from Dr. Bert Vogelstein) [27]. Expression of OPCML-v1 and v2 was analyzed by semi-quantitative RT-PCR. p53 induced a dosage-dependent upregulation of OPCML-v1.

Mentions: Examination of the OPCML promoter revealed multiple HSF and p53 binding elements (MatInspector, http://genomatix.de), indicating that it is a stress- and p53-responsive gene (Fig. 7A). We thus inspected the response of OPCML to environmental stress stimuli. We found that the expression of OPCML-v1 was dramatically elevated in cell lines with an unmethylated promoter, after exposure to various stresses, such as heat shock, UV irradiation and H2O2 treatment. On the contrary, this response was significantly decreased or abolished in cell lines with a methylated promoter (Fig. 7B). Interestingly, OPCML-v2 was not activated in any stress-treated cell line, indicating that it is not stress-responsive, probably due to its tissue-specific expression feature.


OPCML is a broad tumor suppressor for multiple carcinomas and lymphomas with frequently epigenetic inactivation.

Cui Y, Ying Y, van Hasselt A, Ng KM, Yu J, Zhang Q, Jin J, Liu D, Rhim JS, Rha SY, Loyo M, Chan AT, Srivastava G, Tsao GS, Sellar GC, Sung JJ, Sidransky D, Tao Q - PLoS ONE (2008)

The OPCML-v1 promoter is stress- and p53-responsive.(A) Locations of transcription factors (HSF, p53, Sp1, E2F, STAT) binding sites in the promoter are indicated. (B) Up-regulation of OPCML-v1 in response to stress treatments is disrupted in tumor cell lines with a methylated promoter. Normal (NE3, HEK293, NE1) and tumor cell lines (Rael, CNE1, C666-1, HK1) were exposed to 42°C heat shock (HS), UV irradiation, or H2O2 treatments. OPCML-v1 promoter methylation status in each cell line is shown at the bottom. M, methylated; U, unmethylated. (C) H1299 cells were transfected with different amounts of pcDNA3.1+/TP53 (gift from Dr. Bert Vogelstein) [27]. Expression of OPCML-v1 and v2 was analyzed by semi-quantitative RT-PCR. p53 induced a dosage-dependent upregulation of OPCML-v1.
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Related In: Results  -  Collection

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getmorefigures.php?uid=PMC2500176&req=5

pone-0002990-g007: The OPCML-v1 promoter is stress- and p53-responsive.(A) Locations of transcription factors (HSF, p53, Sp1, E2F, STAT) binding sites in the promoter are indicated. (B) Up-regulation of OPCML-v1 in response to stress treatments is disrupted in tumor cell lines with a methylated promoter. Normal (NE3, HEK293, NE1) and tumor cell lines (Rael, CNE1, C666-1, HK1) were exposed to 42°C heat shock (HS), UV irradiation, or H2O2 treatments. OPCML-v1 promoter methylation status in each cell line is shown at the bottom. M, methylated; U, unmethylated. (C) H1299 cells were transfected with different amounts of pcDNA3.1+/TP53 (gift from Dr. Bert Vogelstein) [27]. Expression of OPCML-v1 and v2 was analyzed by semi-quantitative RT-PCR. p53 induced a dosage-dependent upregulation of OPCML-v1.
Mentions: Examination of the OPCML promoter revealed multiple HSF and p53 binding elements (MatInspector, http://genomatix.de), indicating that it is a stress- and p53-responsive gene (Fig. 7A). We thus inspected the response of OPCML to environmental stress stimuli. We found that the expression of OPCML-v1 was dramatically elevated in cell lines with an unmethylated promoter, after exposure to various stresses, such as heat shock, UV irradiation and H2O2 treatment. On the contrary, this response was significantly decreased or abolished in cell lines with a methylated promoter (Fig. 7B). Interestingly, OPCML-v2 was not activated in any stress-treated cell line, indicating that it is not stress-responsive, probably due to its tissue-specific expression feature.

Bottom Line: Pharmacological and genetic demethylation restored OPCML expression, indicating a direct epigenetic silencing.We further found that OPCML is stress-responsive, but this response is epigenetically impaired when its promoter becomes methylated.Ecotopic expression of OPCML led to significant inhibition of both anchorage-dependent and -independent growth of carcinoma cells with endogenous silencing.

View Article: PubMed Central - PubMed

Affiliation: State Key Laboratory in Oncology in South China, Sir YK Pao Center for Cancer, Department of Clinical Oncology, Hong Kong Cancer Institute, Chinese University of Hong Kong, Hong Kong, China.

ABSTRACT

Background: Identification of tumor suppressor genes (TSGs) silenced by CpG methylation uncovers the molecular mechanism of tumorigenesis and potential tumor biomarkers. Loss of heterozygosity at 11q25 is common in multiple tumors including nasopharyngeal carcinoma (NPC). OPCML, located at 11q25, is one of the downregulated genes we identified through digital expression subtraction.

Methodology/principal findings: Semi-quantitative RT-PCR showed frequent OPCML silencing in NPC and other common tumors, with no homozygous deletion detected by multiplex differential DNA-PCR. Instead, promoter methylation of OPCML was frequently detected in multiple carcinoma cell lines (nasopharyngeal, esophageal, lung, gastric, colon, liver, breast, cervix, prostate), lymphoma cell lines (non-Hodgkin and Hodgkin lymphoma, nasal NK/T-cell lymphoma) and primary tumors, but not in any non-tumor cell line and seldom weakly methylated in normal epithelial tissues. Pharmacological and genetic demethylation restored OPCML expression, indicating a direct epigenetic silencing. We further found that OPCML is stress-responsive, but this response is epigenetically impaired when its promoter becomes methylated. Ecotopic expression of OPCML led to significant inhibition of both anchorage-dependent and -independent growth of carcinoma cells with endogenous silencing.

Conclusions/significance: Thus, through functional epigenetics, we identified OPCML as a broad tumor suppressor, which is frequently inactivated by methylation in multiple malignancies.

Show MeSH
Related in: MedlinePlus