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Mdig de-represses H19 large intergenic non-coding RNA (lincRNA) by down-regulating H3K9me3 and heterochromatin.

Chen B, Yu M, Chang Q, Lu Y, Thakur C, Ma D, Yi Z, Chen F - Oncotarget (2013)

Bottom Line: Although mdig can only cause a marginal decrease of the total histone H3 lysine 9 trimethylation (H3K9me3), a significant reduction of H3K9me3 in the promoter region of H19, the paternally imprinted but maternally expressed gene transcribing a large intergenic non-coding RNA (lincRNA), was observed in the cells with mdig overexpression.Demethylation assays using immunoprecipitated mdig and histone H3 peptide substrate suggested that mdig is able to remove the methyl groups from H3K9me3.Taken together, our results imply that mdig is involved in the regulation of H3K9me3 to influence the heterochromatin structure of the genome and the expression of genes important for cell growth or transformation.

View Article: PubMed Central - PubMed

Affiliation: Department of Pharmaceutical Sciences, Eugene Applebaum College of Pharmacy, Wayne State University, 259 Mack Avenue, Detroit, MI, USA.

ABSTRACT
Mineral dust-induced gene (mdig) had been linked to the development of human lung cancers associated with environmental exposure to mineral dust, tobacco smoke or other carcinogens. In the present studies, we demonstrated that the overexpression of mdig in A549 adenocarcinomic human alveolar type II epithelial cells decreases the heterochromatin conformation of the cells and de-represses the transcription of genes in the tandemly repeated DNA regions. Although mdig can only cause a marginal decrease of the total histone H3 lysine 9 trimethylation (H3K9me3), a significant reduction of H3K9me3 in the promoter region of H19, the paternally imprinted but maternally expressed gene transcribing a large intergenic non-coding RNA (lincRNA), was observed in the cells with mdig overexpression. Silencing mdig by either shRNA or siRNA not only increased the level of H3K9me3 in the promoter region of H19 but also attenuated the transcription of H19 long non-coding RNA. Demethylation assays using immunoprecipitated mdig and histone H3 peptide substrate suggested that mdig is able to remove the methyl groups from H3K9me3. Clinically, we found that higher levels of mdig and H19 expression correlate with poorer survival of the lung cancer patients. Taken together, our results imply that mdig is involved in the regulation of H3K9me3 to influence the heterochromatin structure of the genome and the expression of genes important for cell growth or transformation.

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Higher expression of mdig and H19 is associated with poorer survival of cancer patientsA. Kaplan-Meier plot showing poorer survival of the lung cancer patients who were smokers or former smokers and had higher expression of mdig mRNA. B. Higher level of H19 expression correlates with poorer survival of lung cancer patients. C & D. Higher level of mdig is associated with poorer relapse-free survival of the breast cancer patients and poorer progress-free survival of the ovarian cancer patients.
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Figure 5: Higher expression of mdig and H19 is associated with poorer survival of cancer patientsA. Kaplan-Meier plot showing poorer survival of the lung cancer patients who were smokers or former smokers and had higher expression of mdig mRNA. B. Higher level of H19 expression correlates with poorer survival of lung cancer patients. C & D. Higher level of mdig is associated with poorer relapse-free survival of the breast cancer patients and poorer progress-free survival of the ovarian cancer patients.

Mentions: To investigate whether our findings mentioned above could be relevant to the clinical outcomes of human lung and other cancers, we examined the prognostic value of mdig and H19 in a clinical microarray database of lung cancer [37]. The database collected gene expression data that were obtained by using three different versions of Affymetrix HG-U133 microarrays and the survival information of 1,715 lung cancer patients. Two different mdig probe sets, probes 213188_s_at and 213189_at, are presented in this database. After careful analyses of the sequence information of these two probes, we found that the probe set 213188_s_at, in fact, detects the far end of the 3'-UTR of mdig mRNA and the antisense of 3'-UTR of the β-γ-crystallin domain containing 3 (CRYBG) mRNA. Thus, this probe set was not included in our assay. The probe set 213189_at, nonetheless, detects the open-reading frame (ORF) of mdig mRNA, which may much more accurately detect the true expression level of the mdig mRNA. Accordingly, we used this probe set for the correlation assay of mdig expression with the survival of lung cancer patients. Although the mdig level has no significant correlation with the survival of total lung cancer patients, we noted a strong association between a higher level of mdig with poorer overall survival of the lung cancer patients who were smokers or former smokers (Fig. 5A). Because we noted that mdig enhanced H19 expression by demethylating H3K9me3 in the promoter and ICR region of the H19 gene (Figs. 3 and 4), we next aimed to determine whether higher levels of H19 also predict a poorer prognosis for the lung cancer patients. Indeed, a highly significant inverse correlation of higher H19 expression as determined by probe set 217723_x_at with the poorer overall survival of total lung cancer patients was observed (Fig. 5B). To determine whether mdig expression can predict patient survival for other types of cancers, we also analyzed mdig expression and patient survival in breast cancer and ovarian cancer. Interestingly, the prognostic power of mdig was also noted for poorer relapse-free survival of the breast cancer patients (Fig. 5C) and poorer progress-free survival of the ovarian cancer patients (Fig. 5D). These results clearly suggested that the level of mdig expression is an important predictive factor for poorer prognoses of lung cancer, breast cancer and ovarian cancer.


Mdig de-represses H19 large intergenic non-coding RNA (lincRNA) by down-regulating H3K9me3 and heterochromatin.

Chen B, Yu M, Chang Q, Lu Y, Thakur C, Ma D, Yi Z, Chen F - Oncotarget (2013)

Higher expression of mdig and H19 is associated with poorer survival of cancer patientsA. Kaplan-Meier plot showing poorer survival of the lung cancer patients who were smokers or former smokers and had higher expression of mdig mRNA. B. Higher level of H19 expression correlates with poorer survival of lung cancer patients. C & D. Higher level of mdig is associated with poorer relapse-free survival of the breast cancer patients and poorer progress-free survival of the ovarian cancer patients.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3824531&req=5

Figure 5: Higher expression of mdig and H19 is associated with poorer survival of cancer patientsA. Kaplan-Meier plot showing poorer survival of the lung cancer patients who were smokers or former smokers and had higher expression of mdig mRNA. B. Higher level of H19 expression correlates with poorer survival of lung cancer patients. C & D. Higher level of mdig is associated with poorer relapse-free survival of the breast cancer patients and poorer progress-free survival of the ovarian cancer patients.
Mentions: To investigate whether our findings mentioned above could be relevant to the clinical outcomes of human lung and other cancers, we examined the prognostic value of mdig and H19 in a clinical microarray database of lung cancer [37]. The database collected gene expression data that were obtained by using three different versions of Affymetrix HG-U133 microarrays and the survival information of 1,715 lung cancer patients. Two different mdig probe sets, probes 213188_s_at and 213189_at, are presented in this database. After careful analyses of the sequence information of these two probes, we found that the probe set 213188_s_at, in fact, detects the far end of the 3'-UTR of mdig mRNA and the antisense of 3'-UTR of the β-γ-crystallin domain containing 3 (CRYBG) mRNA. Thus, this probe set was not included in our assay. The probe set 213189_at, nonetheless, detects the open-reading frame (ORF) of mdig mRNA, which may much more accurately detect the true expression level of the mdig mRNA. Accordingly, we used this probe set for the correlation assay of mdig expression with the survival of lung cancer patients. Although the mdig level has no significant correlation with the survival of total lung cancer patients, we noted a strong association between a higher level of mdig with poorer overall survival of the lung cancer patients who were smokers or former smokers (Fig. 5A). Because we noted that mdig enhanced H19 expression by demethylating H3K9me3 in the promoter and ICR region of the H19 gene (Figs. 3 and 4), we next aimed to determine whether higher levels of H19 also predict a poorer prognosis for the lung cancer patients. Indeed, a highly significant inverse correlation of higher H19 expression as determined by probe set 217723_x_at with the poorer overall survival of total lung cancer patients was observed (Fig. 5B). To determine whether mdig expression can predict patient survival for other types of cancers, we also analyzed mdig expression and patient survival in breast cancer and ovarian cancer. Interestingly, the prognostic power of mdig was also noted for poorer relapse-free survival of the breast cancer patients (Fig. 5C) and poorer progress-free survival of the ovarian cancer patients (Fig. 5D). These results clearly suggested that the level of mdig expression is an important predictive factor for poorer prognoses of lung cancer, breast cancer and ovarian cancer.

Bottom Line: Although mdig can only cause a marginal decrease of the total histone H3 lysine 9 trimethylation (H3K9me3), a significant reduction of H3K9me3 in the promoter region of H19, the paternally imprinted but maternally expressed gene transcribing a large intergenic non-coding RNA (lincRNA), was observed in the cells with mdig overexpression.Demethylation assays using immunoprecipitated mdig and histone H3 peptide substrate suggested that mdig is able to remove the methyl groups from H3K9me3.Taken together, our results imply that mdig is involved in the regulation of H3K9me3 to influence the heterochromatin structure of the genome and the expression of genes important for cell growth or transformation.

View Article: PubMed Central - PubMed

Affiliation: Department of Pharmaceutical Sciences, Eugene Applebaum College of Pharmacy, Wayne State University, 259 Mack Avenue, Detroit, MI, USA.

ABSTRACT
Mineral dust-induced gene (mdig) had been linked to the development of human lung cancers associated with environmental exposure to mineral dust, tobacco smoke or other carcinogens. In the present studies, we demonstrated that the overexpression of mdig in A549 adenocarcinomic human alveolar type II epithelial cells decreases the heterochromatin conformation of the cells and de-represses the transcription of genes in the tandemly repeated DNA regions. Although mdig can only cause a marginal decrease of the total histone H3 lysine 9 trimethylation (H3K9me3), a significant reduction of H3K9me3 in the promoter region of H19, the paternally imprinted but maternally expressed gene transcribing a large intergenic non-coding RNA (lincRNA), was observed in the cells with mdig overexpression. Silencing mdig by either shRNA or siRNA not only increased the level of H3K9me3 in the promoter region of H19 but also attenuated the transcription of H19 long non-coding RNA. Demethylation assays using immunoprecipitated mdig and histone H3 peptide substrate suggested that mdig is able to remove the methyl groups from H3K9me3. Clinically, we found that higher levels of mdig and H19 expression correlate with poorer survival of the lung cancer patients. Taken together, our results imply that mdig is involved in the regulation of H3K9me3 to influence the heterochromatin structure of the genome and the expression of genes important for cell growth or transformation.

Show MeSH
Related in: MedlinePlus