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BAG1, MGMT, FOXO1, and DNAJA1 as potential drug targets for radiosensitizing cancer cell lines
Bayanika Manunu1, Antonio M Serafin1, John M Akudugu1
1Division of Radiobiology, Department of Medical Imaging and Clinical Oncology, Faculty of Medicine and Health Sciences, Stellenbosch University, South Africa.
Background And Purpose:
Activation of some signaling pathways can promote cell survival and have a negative impact on tumor response to radiotherapy. Here, the role of differences in expression levels of genes related to the poly(ADP-ribose) polymerase-1 (PARP-1), heat shock protein 90 (Hsp90), B-cell lymphoma 2 (Bcl-2), and phosphoinositide 3-kinase (PI3K) pathways in the survival or death of cells following X-ray exposure was investigated.
Methods:
Eight human cell cultures (MCF-7 and MDA-MB-231: breast cancers; MCF-12A: apparently normal breast; A549: lung cancer; L132: normal lung; G28, G44 and G112: glial cancers) were irradiated with X-rays. The colony-forming and real-time PCR based on a custom human pathway RT2 Profiler PCR Array assays were used to evaluate cell survival and gene expression, respectively.
Results:
The surviving fractions at 2 Gy for the cell lines, in order of increasing radioresistance, were found to be as follows: MCF-7 (0.200 ± 0.011), G44 (0.277 ± 0.065), L132 (0.367 ± 0.023), MDA-MB-231 (0.391 ± 0.057), G112 (0.397 ± 0.113), A549 (0.490 ± 0.048), MCF-12A (0.526 ± 0.004), and G28 (0.633 ± 0.094). The rank order of radioresistance at 6 Gy was: MCF-7 < L132 < G44 < MDA-MB-231 < A549 < G28 < G112 < MCF-12A. PCR array data analysis revealed that several genes were differentially expressed between irradiated and unirradiated cell cultures. The following genes, with fold changes: BCL2A1 (21.91), TP53 (8743.75), RAD51 (11.66), FOX1 (65.86), TCP1 (141.32), DNAJB1 (3283.64), RAD51 (51.52), and HSPE1 (12887.29) were highly overexpressed, and BAX (-127.21), FOX1 (-81.79), PDPK1 (-1241.78), BRCA1 (-8.70), MLH1 (-12143.95), BCL2 (-18.69), CCND1 (-46475.98), and GJA1 (-2832.70) were highly underexpressed in the MDA-MB-231, MCF-7, MCF-12A, A549, L132, G28, G44, and G112 cell lines, respectively. The radioresistance in the malignant A549 and G28 cells was linked to upregulation in the apoptotic, DNA repair, PI3K, and Hsp90 pathway genes BAG1, MGMT, FOXO1, and DNAJA1, respectively, and inhibition of these genes resulted in significant radiosensitization.
Conclusions:
Targeting BAG1, MGMT, FOXO1, and DNAJA1 with specific inhibitors might effectively sensitize radioresistant tumors to radiotherapy.
Insights
Investigating gene expression in human cell lines after X-ray exposure revealed that targeting specific genes involved in apoptosis, DNA repair, and signaling pathways can sensitize radioresistant tumors to radiotherapy.
Area of Science:
- Oncology
- Molecular Biology
- Radiotherapy Research
Background:
- Signaling pathways influence cell survival and tumor response to radiotherapy.
- Gene expression differences can impact cell fate after radiation exposure.
Purpose of the Study:
- To investigate the role of gene expression in the poly(ADP-ribose) polymerase-1 (PARP-1), heat shock protein 90 (Hsp90), B-cell lymphoma 2 (Bcl-2), and phosphoinositide 3-kinase (PI3K) pathways in cell survival following X-ray exposure.
- To correlate gene expression profiles with radioresistance in various human cell lines.
Main Methods:
- Irradiation of eight human cell cultures (breast, lung, and glial cancers, and normal breast/lung cells) with X-rays.
- Evaluation of cell survival using colony-forming assays.
- Assessment of gene expression using real-time PCR with a custom human pathway RT2 Profiler PCR Array.
Main Results:
- Significant differences in radioresistance were observed across cell lines, with MCF-7 cells being the most sensitive and G28 cells the most resistant.
- PCR array analysis identified differentially expressed genes, including overexpression of *BCL2A1*, *TP53*, *RAD51*, *FOX1*, *TCP1*, *DNAJB1*, and *HSPE1*, and underexpression of *BAX*, *FOX1*, *PDPK1*, *BRCA1*, *MLH1*, *BCL2*, *CCND1*, and *GJA1*.
- Radioresistance in A549 and G28 cells correlated with the upregulation of apoptotic, DNA repair, PI3K, and Hsp90 pathway genes (*BAG1*, *MGMT*, *FOXO1*, and *DNAJA1*).
Conclusions:
- Upregulation of *BAG1*, *MGMT*, *FOXO1*, and *DNAJA1* is linked to radioresistance in certain cancer cell lines.
- Inhibition of these specific genes (*BAG1*, *MGMT*, *FOXO1*, *DNAJA1*) significantly enhanced radiosensitivity.
- Targeting these genes with specific inhibitors presents a potential strategy to sensitize radioresistant tumors to radiotherapy.
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