Wei Sha

Heart failure with preserved ejection fraction (HFpEF) lacks effective disease-modifying therapies. This study identifies a novel cardioprotective mechanism in which growth hormone-releasing hormone activates hypoxia-inducible factor-1α (HIF-1α) in cardiomyocytes under normoxic conditions. Using human iPSC-derived cardiomyocytes and a cardiometabolic HFpEF mouse model, the authors show that cardiomyocyte HIF-1α is required for GHRH-mediated improvements in diastolic function, myocardial mechanics, and exercise capacity, revealing a previously unrecognized therapeutic axis for HFpEF.

Alzheimer’s disease (AD) is a progressive neurodegenerative disorder characterized by amyloid-β (Aβ) accumulation, tau hyperphosphorylation, neuroinflammation, and synaptic loss. Existing therapies provide only modest symptomatic relief and fail to slow disease progression. Beyond its role in promoting pituitary growth hormone (GH) secretion, growth hormone-releasing hormone (GHRH) has shown neuroprotective effects in experimental ischemic stroke and spinal muscular atrophy. Here, we explored the therapeutic potential of GHRH and its agonist MR-409 in AD models. In vitro, GHRH(1-44)NH₂ promoted survival, proliferation, and neuronal differentiation of rat hippocampal neural stem cells (NSCs) and human SH-SY5Y neuroblastoma cells under growth factor deprivation and amyloid beta (Aβ) _1-42 exposure. These effects involved the cAMP/PKA/CREB, ERK1/2, and PI3K/Akt signaling pathways. GHRH also attenuated Aβ-induced neurotoxicity by reducing apoptosis, suppressing GSK-3β activity and tau phosphorylation, restoring nuclear β-catenin, and inhibiting NF-κB-mediated inflammation. In vivo, subcutaneous administration of MR-409 in 5xFAD mice reduced Aβ deposition, tau phosphorylation, gliosis, and proinflammatory cytokine expression. In addition, MR-409 mitigated neuronal and synaptic loss, activated survival and neurogenic pathways, and improved cognitive performance, without altering systemic GH and IGF1 levels. MR-409 also elevated NRF2 mRNA expression while reducing its negative regulator KEAP1. Overall, these findings indicate that GHRH and its analog MR-409 exert neuroprotective effects by modulating key pathological features of AD, including neurodegeneration, impaired neurogenesis, neuroinflammation, and oxidative stress. Given their ability to modulate multiple pathological pathways, GHRH agonists may represent promising therapeutic candidates for AD and other neurodegenerative disorders.

Gulf War illness (GWI) is a multi-symptom disorder affecting veterans of the Persian Gulf operations. Persistent neuroendocrine dysregulation contributes to impairing cognitive capacity and generates anxiety-like behavior. Effective treatments for this illness are challenging due to compromised metabolism, increased oxidative stress and neuroinflammation, perpetuated by chronic stress and hypothalamic–pituitary–adrenal (HPA) axis dysfunction. This neuroinflammation can be alleviated with synthetic antagonistic analogs of the growth hormone-releasing hormone (GHRH) through modulation of the HPA axis. We evaluated the efficacy of the GHRH antagonist analog, MIA-690, against cognitive impairment and anxiety-like behavior in GWI. Mice exposed to an experimental GWI model involving corticosterone (CORT) and diisopropylfluorophosphate (DFP), followed by CORT and lipopolysaccharide (LPS), received a daily subcutaneous dose of 10 μg of MIA-690 for 10 days. Assessments of spatial memory, recognition capacity, somatic health, anxiety and innate survival were carried out, combining the Morris water maze (MWM), novel object recognition (NORT), grip strength (GST), and open field (OFT) tests. Learning efficiency was selectively enhanced in females using the MWM. There were no significant differences in the recall capacity and performance on the OFT, NOR, and GST tasks. Our findings suggest that the MIA-690 dosage is sufficient to improve learning deficits in experimental GWI exposures.

Heart failure (HF) with preserved ejection fraction (HFpEF) carries a high mortality and remains a major therapeutic challenge. Effective, targeted therapies capable of reversing HFpEF pathophysiology are urgently needed. We previously demonstrated that activation of the cardiac growth hormone-releasing hormone (GHRH) pathway using high potency synthetic agonists of GHRH (GHRH-agonists: MR-356 and MR-409) improves the HFpEF phenotype in both large and small animal models, including in a murine model of cardiometabolic HFpEF (High fat diet + the nitric oxide synthase inhibitor L-NAME [HFD+L-NAME]). Here we sought to define the downstream signaling pathways responsible for this effect. A transcriptomic screen in human iPSC-derived cardiomyocytes (hiPSC-CMs) identified the hypoxia-inducible factor (HIF)-1α pathway as being activated by GHRH receptor (GHRHR) signaling, revealing an oxygen-independent mechanism of HIF-1α activation. Based on this finding, we investigated the interaction between the cardioprotective effects of the GHRH-agonist MR-356 and HIF-1α pathway activation in the murine HFD+L-NAME model of cardiometabolic HFpEF. We generated a cardiomyocyte-specific HIF-1α knockout (HIF-1α ^CM KO) mouse line and demonstrated that our previously reported beneficial effects of GHRH-agonist administration were completely abolished in HIF-1α ^CM KO mice. Together, these findings establish the GHRHR-HIF-1α axis as a central pathway integrating metabolic and contractile remodeling, suggesting that therapeutic targeting of this axis represents a novel disease-modifying approach to treating cardiometabolic HFpEF.

Background. Antagonists of GHRH have experimental therapeutic value, but as single agents are not likely to improve clinical outcomes, especially in advanced prostate cancer resistant to androgen deprivation therapy. Our objective is to identify anti-cancer drugs that, in combination with MIA-602 or -690 GHRH antagonists, increase cell death in all types of prostate cancer. Methods/Results. We identified inhibitors of PI3Kα or PI3Kβ that consistently increased cell death when combined with MIA-602/690. The PI3K family is critical in mediating upstream signals from receptors to downstream AKT/mTOR signaling pathways and has an important role in cancer progression. The results revealed that MIA-602/690 alone decreased androgen receptors and likely enhanced PI3K (negative feedback), which was then countered by the addition of PI3K inhibitors. Furthermore, the MIA-602/690 + PI3K inhibitor combination affected multiple signaling pathways, including apoptosis (anti-apoptotic Mcl-1L switching to pro-apoptotic Mcl-1S), proliferation (E2F1, cyclin A), PI3Kα/β, AKT, and ERK. Similar results were obtained with a more clinically relevant acetate salt form of MIA-602/690. The identification of PI3K as a drug target for prostate cancer is significant because PTEN (negative regulator of PI3K) loss of function occurs in 40–50% and PIK3CA mutation/amplification occurs in 60% of prostate cancer patients, leading to a poor prognosis. Conclusion. The ability of the MIA-602/690 + PI3K inhibitor combination to alter multiple signaling pathways may weaken the activation of adaptive mechanisms resulting from each drug and improve efficacy.

Growth hormone-releasing hormone (GHRH) antagonists exert antitumor functions in different experimental cancers. However, their role in combination with radiotherapy in non-small cell lung cancer (NSCLC) remains unknown. Therefore, we investigated the radiosensitizing effect of GHRH antagonists in NSCLC. A549 and H522 NSCLC cell lines were exposed to ionizing radiation (IR) and GHRH antagonists MIA-602 and MIA-690, either individually or in combination. Cell viability and proliferation were evaluated by MTT, BrdU, flow cytofluorimetry, and clonogenic assays; gene and protein expression, signaling pathways, and apoptosis were analyzed by real-time PCR, Western blot, annexin staining, and caspase-3 assay. GHRH antagonists showed antitumor effects alone and potentiated IR-induced inhibition of cell viability and proliferation. The combination of MIA-690 and IR decreased the expression of GHRH receptor, its oncogenic splice variant 1, and IGF1 mRNA levels. Additionally, cell cycle inhibitors and proapoptotic markers were upregulated, whereas cyclins, oncogenic MYC, and the antiapoptotic protein Bcl-2 were downregulated. Radioresistance was prevented by MIA-690, which also blunted epithelial–mesenchymal transition by enhancing E-cadherin and reducing mesenchymal, oxidative, and proangiogenic effectors. Finally, both MIA-602 and MIA-690 enhanced radiosensitivity in primary human NSCLC cells. These findings highlight the potential of GHRH antagonists as radiosensitizers in NSCLC treatment.

Antagonists of GHRH have experimental therapeutic value but as single agents are not likely to improve clinical outcomes, especially in advanced prostate cancer resistant to androgen deprivation therapy. Our objective is to identify anti-cancer drugs that in combination with MIA-602 or -690 GHRH antagonists increase cell death in all types of prostate cancer. We identified inhibitors of PI3Ka or PI3Kb that consistently increased cell death when combined with MIA-602/690. The PI3K family is critical in mediating upstream signals from receptors to downstream AKT/mTOR signaling pathways and has an important role in cancer progression. Results revealed that MIA-602/690 alone decreased androgen receptor and likely enhanced PI3K (negative feedback), which is then countered by addition of PI3K inhibitors. Furthermore, MIA-602/690 + PI3K inhibitor combination affected multiple signaling pathways, including apoptosis (anti-apoptotic Mcl-1L switch to pro-apoptotic Mcl-1S), proliferation (E2F1, cyclin A), PI3Ka/b, AKT, and ERK. Similar results were obtained with a more clinically relevant acetate salt form of MIA-602/690. Identification of PI3K as a drug target for prostate cancer is significant because PTEN (negative regulator of PI3K) loss of function occurs in 40-50% and PIK3CA mutation/amplification occurs in 60% of prostate cancer patients, leading to a poor prognosis. The ability of the MIA-602/690 + PI3K inhibitor combination to alter multiple signaling pathways may weaken the activation of adaptive mechanisms resulting from each drug and improve efficacy.

Growth hormone-releasing hormone (GHRH) and its ability to stimulate the production and release of growth hormone from the pituitary were discovered more than four decades ago. Since then, this hormone has been studied extensively and research into its functions is still ongoing. GHRH has multifaceted roles beyond the originally identified functions that encompass a variety of direct extrapituitary effects. In this Review, we illustrate the different biological activities of GHRH, covering the effects of GHRH agonists and antagonists in physiological and pathological contexts, along with the underlying mechanisms. GHRH and GHRH analogues have been implicated in cell growth, wound healing, cell death, inflammation, immune functions, mood disorders, feeding behaviour, neuroprotection, diabetes mellitus and obesity, as well as cardiovascular, lung and neurodegenerative diseases and some cancers. The positive effects observed in preclinical models in vitro and in vivo strongly support the potential use of GHRH agonists and antagonists as clinical therapeutics.