A GHRH receptor antagonist peptide (MIA-690) synergized with the cancer drug gefitinib to suppress castration-resistant prostate cancer growth by blocking a receptor crosstalk survival pathway.
Synergistic effectGHRH-R peptide antagonist MIA-690 combined with EGFR inhibitor gefitinib suppressed castration-resistant prostate cancer growth more than either alone
What the researchers found
The GHRH receptor antagonist peptide MIA-690 showed synergistic antitumor effects when combined with the EGFR inhibitor gefitinib in castration-resistant prostate cancer (CRPC) PC-3 cells. The combination inhibited cell viability, adhesion, and metalloprotease activity more effectively than either agent alone, and induced cell cycle arrest. These effects were confirmed in vivo in nude mice bearing PC-3 tumors 36 days after inoculation, demonstrating that blocking GHRH-R/EGFR crosstalk is a viable strategy against treatment-resistant prostate cancer.
Why it matters
Castration-resistant prostate cancer is notoriously difficult to treat because tumors find alternative survival pathways. This study reveals that GHRH receptors can transactivate EGFR signaling, providing a survival escape route, and shows that a peptide antagonist can block this crosstalk — opening a potential new combination therapy approach for advanced prostate cancer.
The numbers in context
PC-3 cell line · synergistic effect of MIA-690 + gefitinib · 36-day nude mouse tumor model · inhibited viability, adhesion, and metalloprotease activity
How the study worked
In vitro experiments used PC-3 castration-resistant prostate cancer cells treated with MIA-690 (GHRH-R antagonist) and/or gefitinib (EGFR inhibitor). Researchers assessed cell viability, adhesion, gelatinolytic (metalloprotease) activity, and cell cycle progression. In vivo validation used subcutaneous PC-3 tumor xenografts in athymic nude mice evaluated 36 days post-inoculation.
Who was studied
PC-3 prostate cancer cell line and nude mouse xenograft tumor model
What this study cannot tell us
PC-3 is a single cell line model of CRPC; other CRPC cell lines and patient-derived models were not tested. The nude mouse xenograft model lacks a functional immune system, which limits translation to immunocompetent settings. Specific dosing, tumor size measurements, and statistical details are not provided in the abstract.
How to read the evidence
This is a preclinical study with both in vitro (cell line) and in vivo (mouse xenograft) validation. While it demonstrates a clear synergistic mechanism, it uses a single cell line and immunodeficient mouse model, placing it at an early stage of preclinical evidence.
When this study was published
Published in 2024, this study reflects ongoing efforts to develop GHRH-based peptide therapeutics for cancer, building on decades of work by the Schally laboratory on hypothalamic peptide hormone analogs in oncology.
The bigger picture
GHRH receptor antagonists represent a growing class of peptide therapeutics being explored for cancer. This study adds prostate cancer to the list and reveals a specific mechanism — GHRH-R/EGFR transactivation — that could be targeted. The combination approach of peptide antagonist plus small molecule inhibitor may offer a template for overcoming treatment resistance in other cancers that rely on similar receptor crosstalk.
Questions still open
- Would this GHRH-R antagonist + EGFR inhibitor combination work in other CRPC cell lines or patient-derived tumor models?
- Could MIA-690 be combined with other targeted therapies beyond gefitinib for broader anti-cancer effects?
- Does this GHRH-R/EGFR crosstalk mechanism also operate in other hormone-resistant cancers like breast cancer?
Common questions
What is castration-resistant prostate cancer and why is it so hard to treat?
How does a GHRH receptor antagonist peptide fight cancer?
Read the original research
Antagonist of Growth Hormone-Releasing Hormone Receptor MIA-690 Suppresses the Growth of Androgen-Independent Prostate Cancers.
International journal of molecular sciences, 25(20)
Citation
Muñoz-Moreno, Laura; Gómez-Calcerrada, M Isabel; Arenas, M Isabel; Carmena, M José; Prieto, Juan C; Schally, Andrew V; Bajo, Ana M. (2024). Antagonist of Growth Hormone-Releasing Hormone Receptor MIA-690 Suppresses the Growth of Androgen-Independent Prostate Cancers.. International journal of molecular sciences, 25(20). https://doi.org/10.3390/ijms252011200