<abstract xmlns="http://www.w3.org/1999/xhtml">
<sec><h3>Objective.</h3>
<p>Homeobox genes play an important role in health and disease including oncogenesis. The present investigation aimed to study ERN1-dependent hypoxic regulation of the expression of genes encoding homeobox proteins MEIS (zinc finger E-box binding homeobox 2) and LIM homeobox 1 family, SPAG4 (sperm associated antigen 4) and NKX3-1 (NK3 homeobox 1) in U87MG glioblastoma cells in response to inhibition of ERN1 (endoplasmic reticulum to nucleus signaling 1) for evaluation of their possible significance in the control of glioblastoma growth.</p>
</sec>
<sec><h3>Methods.</h3>
<p>The expression level of homeobox genes was studied in control (transfected by vector) and ERN1 knockdown U87MG glioblastoma cells under hypoxia induced by dimethyloxalylglycine (0.5 mM for 4 h) by quantitative polymerase chain reaction and normalized to ACTB.</p>
</sec>
<sec><h3>Results.</h3>
<p>It was found that hypoxia down-regulated the expression level of <italic>LHX2</italic>, <italic>LHX6</italic>, <italic>MEIS2</italic>, and <italic>NKX3</italic>-1 genes but up-regulated the expression level of <italic>MEIS1</italic>, <italic>LHX1</italic>, <italic>MEIS3</italic>, and <italic>SPAG4</italic> genes in control glioblastoma cells. At the same time, ERN1 knockdown of glioblastoma cells significantly modified the sensitivity of all studied genes to a hypoxic condition. Thus, ERN1 knockdown of glioblastoma cells removed the effect of hypoxia on the expression of <italic>MEIS1</italic> and <italic>LHX1</italic> genes, but increased the sensitivity of <italic>MEIS2</italic>, <italic>LHX2</italic>, and <italic>LHX6</italic> genes to hypoxia. However, the expression of <italic>MEIS3</italic>, <italic>NKX3</italic>-1, and <italic>SPAG4</italic> genes had decreased sensitivity to hypoxia in ERN1 knockdown glioblastoma cells. Moreover, more pronounced changes under the conditions of ERN1 inhibition were detected for the pro-oncogenic gene <italic>SPAG4</italic>.</p>
</sec>
<sec><h3>Conclusion.</h3>
<p>The results of the present study demonstrate that hypoxia affected the expression of homeobox genes <italic>MEIS1</italic>, <italic>MEIS2</italic>, <italic>MEIS3</italic>, <italic>LHX1</italic>, <italic>LHX2</italic>, <italic>LHX6</italic>, <italic>SPAG4</italic>, and <italic>NKX3-1</italic> in U87MG glioblastoma cells in gene-specific manner and that the sensitivity of all studied genes to hypoxia condition is mediated by ERN1, the major pathway of the endoplasmic reticulum stress signaling, and possibly contributed to the control of glioblastoma growth. A fundamentally new results of this work is the establishment of the fact regarding the dependence of hypoxic regulation of SPAG4 gene expression on ER stress, in particular ERN1, which is associated with suppression of cell proliferation and tumor growth.</p>
</sec>
</abstract>

Objective.
Homeobox genes play an important role in health and disease including oncogenesis. The present investigation aimed to study ERN1-dependent hypoxic regulation of the expression of genes encoding homeobox proteins MEIS (zinc finger E-box binding homeobox 2) and LIM homeobox 1 family, SPAG4 (sperm associated antigen 4) and NKX3-1 (NK3 homeobox 1) in U87MG glioblastoma cells in response to inhibition of ERN1 (endoplasmic reticulum to nucleus signaling 1) for evaluation of their possible significance in the control of glioblastoma growth.

Methods.
The expression level of homeobox genes was studied in control (transfected by vector) and ERN1 knockdown U87MG glioblastoma cells under hypoxia induced by dimethyloxalylglycine (0.5 mM for 4 h) by quantitative polymerase chain reaction and normalized to ACTB.

Results.
It was found that hypoxia down-regulated the expression level of LHX2, LHX6, MEIS2, and NKX3-1 genes but up-regulated the expression level of MEIS1, LHX1, MEIS3, and SPAG4 genes in control glioblastoma cells. At the same time, ERN1 knockdown of glioblastoma cells significantly modified the sensitivity of all studied genes to a hypoxic condition. Thus, ERN1 knockdown of glioblastoma cells removed the effect of hypoxia on the expression of MEIS1 and LHX1 genes, but increased the sensitivity of MEIS2, LHX2, and LHX6 genes to hypoxia. However, the expression of MEIS3, NKX3-1, and SPAG4 genes had decreased sensitivity to hypoxia in ERN1 knockdown glioblastoma cells. Moreover, more pronounced changes under the conditions of ERN1 inhibition were detected for the pro-oncogenic gene SPAG4.

Conclusion.
The results of the present study demonstrate that hypoxia affected the expression of homeobox genes MEIS1, MEIS2, MEIS3, LHX1, LHX2, LHX6, SPAG4, and NKX3-1 in U87MG glioblastoma cells in gene-specific manner and that the sensitivity of all studied genes to hypoxia condition is mediated by ERN1, the major pathway of the endoplasmic reticulum stress signaling, and possibly contributed to the control of glioblastoma growth. A fundamentally new results of this work is the establishment of the fact regarding the dependence of hypoxic regulation of SPAG4 gene expression on ER stress, in particular ERN1, which is associated with suppression of cell proliferation and tumor growth.

ERN1 knockdown modifies the hypoxic regulation of homeobox gene expression in U87MG glioblastoma cells

Department of Molecular Biology, Palladin Institute of Biochemistry

Endocrine Regulations

This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License.

Objective.
Homeobox genes play an important role in health and disease including oncogenesis. The present investigation aimed to study ERN1-dependent hypoxic...

ERN1 knockdown modifies the hypoxic regulation of homeobox gene expression in U87MG glioblastoma cells

Published Online: Apr 02, 2024

Page range: 47 - 56

DOI: https://doi.org/10.2478/enr-2024-0006

Keywords
U87MG glioblastoma cells, ERN1 knockdown, hypoxia, homeobox genes, mRNA expression

© 2024 Daria A. Krasnytska et al., published by Sciendo

This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License.

ERN1 knockdown modifies the hypoxic regulation of homeobox gene expression in U87MG glioblastoma cells

Published Online: Apr 02, 2024

Page range: 47 - 56

DOI: https://doi.org/10.2478/enr-2024-0006

KeywordsU87MG glioblastoma cells, ERN1 knockdown, hypoxia, homeobox genes, mRNA expression

© 2024 Daria A. Krasnytska et al., published by Sciendo

This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License.

Keywords
U87MG glioblastoma cells, ERN1 knockdown, hypoxia, homeobox genes, mRNA expression