Limits...
Endoplasmic reticulum protein 29 (ERp29) confers radioresistance through the DNA repair gene, O(6)-methylguanine DNA-methyltransferase, in breast cancer cells.

Chen S, Zhang Y, Zhang D - Sci Rep (2015)

Bottom Line: Our previous studies have demonstrated a significant role of ERp29 in breast cancer cell survival against doxorubicin-induced genotoxic stress.We here reported that ERp29 expression in the triple negative MDA-MB-231 breast cancer cells significantly increased cell survival against ionizing radiation.In addition, radiation treatment in the MGMT-knockdown cells elevated phosphorylation of γ-H2AX and cleavage of caspase 3, indicating that depletion of MGMT facilitates DNA double strands breaks and increases cell apoptosis.

View Article: PubMed Central - PubMed

Affiliation: Department of Gastroenterology, The First Affiliated Hospital, College of Medicine, Zhejiang University, Hangzhou, China.

ABSTRACT
Resistance of cancer cells to radiotherapy is a major clinical problem in cancer treatment. Therefore, understanding the molecular basis of cellular resistance to radiotherapy and identification of novel targets are essential for improving treatment efficacy for cancer patients. Our previous studies have demonstrated a significant role of ERp29 in breast cancer cell survival against doxorubicin-induced genotoxic stress. We here reported that ERp29 expression in the triple negative MDA-MB-231 breast cancer cells significantly increased cell survival against ionizing radiation. Methylation PCR array analysis identified that ERp29 expression increased promoter hypomethylation of the DNA repair gene, O(6)-methylguanine DNA-methyltransferase (MGMT), by downregulating DNA methyltransferase 1. Knockdown of MGMT in the ERp29-transfected cancer cells increased radiosensitivity, leading to a decreased post-irradiation survival. In addition, radiation treatment in the MGMT-knockdown cells elevated phosphorylation of γ-H2AX and cleavage of caspase 3, indicating that depletion of MGMT facilitates DNA double strands breaks and increases cell apoptosis. Hence, our studies prove a novel function of ERp29\MGMT in cancer cell survival against radiation. Targeting ERp29\MGMT axis may be useful for providing better treatment efficacy in combination with radiotherapy in breast cancer.

No MeSH data available.


Related in: MedlinePlus

MGMT is a downstream target of ERp29.ERp29-transfected cells (cone B) (a) or MCF7 cells (b) were treated with ERp29 siRNA (#1) or MGMT siRNA (#3) or control siRNA and the expression of ERp29 and MGMT was analysed. ERp29 knockdown decreased the expression of MGMT whereas MGMT knockdown was unable to decrease the level of ERp29 in both clone B cells (a) and MCF-7 cells (b). **p < 0.01, ***p < 0.001, relative to control.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC4588584&req=5

f4: MGMT is a downstream target of ERp29.ERp29-transfected cells (cone B) (a) or MCF7 cells (b) were treated with ERp29 siRNA (#1) or MGMT siRNA (#3) or control siRNA and the expression of ERp29 and MGMT was analysed. ERp29 knockdown decreased the expression of MGMT whereas MGMT knockdown was unable to decrease the level of ERp29 in both clone B cells (a) and MCF-7 cells (b). **p < 0.01, ***p < 0.001, relative to control.

Mentions: To further understand whether MGMT is a downstream target of ERp29, the MB-231/ERp29 cells (clone B) were respectively treated for 48 h with MGMT siRNA, or ERp29 siRNA, or the non-targeted control siRNA. We showed that depletion of ERp29 in MB-231/ERp29 cells reduced the level of MGMT compared to those treated with control siRNA (Fig. 4a). However, depletion of MGMT was unable to affect the level of total ERp29 (endogenously and exogenously expressed) in these cells (Fig. 4a). This is reflected by the fact that the overall ERp29 level in the MGMT siRNA-treated MB-231/ERp29 cells was similar to that expressed in the untreated or control siRNA-treated MB-231/ERp29 cells.


Endoplasmic reticulum protein 29 (ERp29) confers radioresistance through the DNA repair gene, O(6)-methylguanine DNA-methyltransferase, in breast cancer cells.

Chen S, Zhang Y, Zhang D - Sci Rep (2015)

MGMT is a downstream target of ERp29.ERp29-transfected cells (cone B) (a) or MCF7 cells (b) were treated with ERp29 siRNA (#1) or MGMT siRNA (#3) or control siRNA and the expression of ERp29 and MGMT was analysed. ERp29 knockdown decreased the expression of MGMT whereas MGMT knockdown was unable to decrease the level of ERp29 in both clone B cells (a) and MCF-7 cells (b). **p < 0.01, ***p < 0.001, relative to control.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4588584&req=5

f4: MGMT is a downstream target of ERp29.ERp29-transfected cells (cone B) (a) or MCF7 cells (b) were treated with ERp29 siRNA (#1) or MGMT siRNA (#3) or control siRNA and the expression of ERp29 and MGMT was analysed. ERp29 knockdown decreased the expression of MGMT whereas MGMT knockdown was unable to decrease the level of ERp29 in both clone B cells (a) and MCF-7 cells (b). **p < 0.01, ***p < 0.001, relative to control.
Mentions: To further understand whether MGMT is a downstream target of ERp29, the MB-231/ERp29 cells (clone B) were respectively treated for 48 h with MGMT siRNA, or ERp29 siRNA, or the non-targeted control siRNA. We showed that depletion of ERp29 in MB-231/ERp29 cells reduced the level of MGMT compared to those treated with control siRNA (Fig. 4a). However, depletion of MGMT was unable to affect the level of total ERp29 (endogenously and exogenously expressed) in these cells (Fig. 4a). This is reflected by the fact that the overall ERp29 level in the MGMT siRNA-treated MB-231/ERp29 cells was similar to that expressed in the untreated or control siRNA-treated MB-231/ERp29 cells.

Bottom Line: Our previous studies have demonstrated a significant role of ERp29 in breast cancer cell survival against doxorubicin-induced genotoxic stress.We here reported that ERp29 expression in the triple negative MDA-MB-231 breast cancer cells significantly increased cell survival against ionizing radiation.In addition, radiation treatment in the MGMT-knockdown cells elevated phosphorylation of γ-H2AX and cleavage of caspase 3, indicating that depletion of MGMT facilitates DNA double strands breaks and increases cell apoptosis.

View Article: PubMed Central - PubMed

Affiliation: Department of Gastroenterology, The First Affiliated Hospital, College of Medicine, Zhejiang University, Hangzhou, China.

ABSTRACT
Resistance of cancer cells to radiotherapy is a major clinical problem in cancer treatment. Therefore, understanding the molecular basis of cellular resistance to radiotherapy and identification of novel targets are essential for improving treatment efficacy for cancer patients. Our previous studies have demonstrated a significant role of ERp29 in breast cancer cell survival against doxorubicin-induced genotoxic stress. We here reported that ERp29 expression in the triple negative MDA-MB-231 breast cancer cells significantly increased cell survival against ionizing radiation. Methylation PCR array analysis identified that ERp29 expression increased promoter hypomethylation of the DNA repair gene, O(6)-methylguanine DNA-methyltransferase (MGMT), by downregulating DNA methyltransferase 1. Knockdown of MGMT in the ERp29-transfected cancer cells increased radiosensitivity, leading to a decreased post-irradiation survival. In addition, radiation treatment in the MGMT-knockdown cells elevated phosphorylation of γ-H2AX and cleavage of caspase 3, indicating that depletion of MGMT facilitates DNA double strands breaks and increases cell apoptosis. Hence, our studies prove a novel function of ERp29\MGMT in cancer cell survival against radiation. Targeting ERp29\MGMT axis may be useful for providing better treatment efficacy in combination with radiotherapy in breast cancer.

No MeSH data available.


Related in: MedlinePlus