Growth Hormone-Releasing Hormone Antagonists Increase Radiosensitivity in Non-Small Cell Lung Cancer Cells

Area of Science:

• Oncology
• Molecular Biology
• Radiotherapy Research

Background:

• Growth hormone-releasing hormone (GHRH) antagonists demonstrate antitumor activity in various cancers.
• The radiosensitizing potential of GHRH antagonists in non-small cell lung cancer (NSCLC) is unexplored.

Purpose of the Study:

• To investigate the radiosensitizing effects of GHRH antagonists in NSCLC.
• To evaluate the combination therapy of GHRH antagonists and ionizing radiation (IR) in NSCLC cell lines.

Main Methods:

• Utilized NSCLC cell lines (A549, H522) treated with IR and GHRH antagonists (MIA-602, MIA-690).
• Assessed cell viability, proliferation, gene/protein expression, signaling pathways, and apoptosis using MTT, BrdU, flow cytometry, clonogenic assays, real-time PCR, Western blot, and caspase-3 assays.
• Examined effects on GHRH receptor, IGF1, cell cycle regulators, apoptosis markers, MYC, Bcl-2, and epithelial-mesenchymal transition (EMT) markers.

Main Results:

• GHRH antagonists exhibited antitumor effects and potentiated IR-induced inhibition of cell viability and proliferation.
• Combination therapy decreased GHRH receptor, splice variant 1, and IGF1 mRNA levels.
• Upregulation of cell cycle inhibitors and proapoptotic markers, downregulation of cyclins, MYC, and Bcl-2 observed.
• MIA-690 prevented radioresistance, blunted EMT, and enhanced radiosensitivity in primary human NSCLC cells.

Conclusions:

• GHRH antagonists act as effective radiosensitizers in NSCLC.
• Combination of GHRH antagonists with radiotherapy presents a promising therapeutic strategy for NSCLC.