Sun, W.-C. | bioRxiv Science

bioRxiv2025

The activation of fibroblast growth factor receptor 1 provides therapeutic benefit in a mouse model of Alzheimer's disease

Alzheimers disease (AD) is a neurodegenerative disease that is characterized by the accumulation of amyloid plaque and neurofibrillary tangles, ultimately impairing multiple cognitive domains. Both plaques and tangles cause neuronal damage and stimulate inflammatory responses in glial cells. The fibroblast growth factor receptor 1 (FGFR1)-mediated signaling pathways support the function of damaged neurons and modulate inflammatory response. The FGFR1 agonists, including Fibroblast growth factor 1 (FGF1) and FG loop peptide (FGL), have been implicated in multiple disease therapy. Whether FGFR1 agonists can improve pathology and cognitive function in AD remains unknown. Here, we showed that administration of FGF1 and FGL to the AD mouse model reversed spatial memory impairment, enhanced neurogenesis, suppressed reactive astrogliosis, and restricted dystrophic neurite. However, only FGF1 treatment reduced the deposition of senile plaque. In microglial culture studies, FGF1 improves the phagocytosis ability of microglia, which contributes to the clearance of plaques. Together, our findings suggested that FGFR1 agonists alleviate pathology and cognitive impairment via immunomodulatory and improve neuronal health in the AD mouse model. HighlightsFGFR1 agonists alleviate memory deficits in AD mice. FGFR1 agonists increase adult neurogenesis and limit dystrophic neurites in AD mice. FGFR1 agonists increase plaque-associated microglia in vivo and promote phagocytosis in vitro.

neuroscience↗

bioRxiv2023

Tumor- and Nerve-Derived Axon Guidance Molecule Promotes Pancreatic Ductal Adenocarcinoma Progression and Metastasis through Macrophage Reprogramming

Axon guidance molecules were found to be the gene family most frequently altered in pancreatic ductal adenocarcinoma (PDA) through mutations and copy number changes. However, the exact molecular mechanism regarding PDA development remained unclear. Using genetically engineered mouse models to examine one of the axon guidance molecules, semaphorin 3D (SEMA3D), we found a dual role for tumor-derived SEMA3D in malignant transformation of pancreatic epithelial cells and a role for nerve-derived SEMA3D in PDA development. This was demonstrated by the pancreatic-specific knockout of the SEMA3D gene from the KRASG12D and TP53R172H mutation knock-in, PDX1-Cre (KPC) mouse model which demonstrated a delayed tumor initiation and growth comparing to the original KPC mouse model. Our results showed that SEMA3D knockout skews the macrophages in the pancreas away from M2 polarization, providing a potential mechanistic role of tumor-derived SEMA3D in PDA development. The KPC mice with the SEMA3D knockout remained metastasis-free, however, died from primary tumor growth. We then tested the hypothesis that a potential compensation mechanism could result from SEMA3D which is naturally expressed by the intratumoral nerves. Our study further revealed that nerve-derived SEMA3D does not reprogram macrophages directly, but reprograms macrophages indirectly through ARF6 signaling and lactate production in PDA tumor cells. SEMA3D increases tumor-secreted lactate which is sensed by GPCR132 on macrophages and subsequently stimulates pro-tumorigenic M2 polarization in vivo. Tumor intrinsic- and extrinsic-SEMA3D induced ARF6 signaling through its receptor Plexin D1 in a mutant KRAS-dependent manner. Consistently, RNA sequencing database analysis revealed an association of higher KRASMUT expression with an increase in SEMA3D and ARF6 expression in human PDAs. Moreover, multiplex immunohistochemistry analysis showed an increased number of M2-polarized macrophages proximal to nerves in human PDA tissue expressing SEMA3D. Thus, this study suggests altered expression of SEMA3D in tumor cells lead to acquisition of cancer-promoting functions and the axon guidance signaling originating from nerves is "hijacked" by tumor cells to support their growth. Other axon guidance and neuronal development molecules may play a similar dual role which is worth further investigation. One sentence summaryTumor- and nerve-derived SEMA3D promotes tumor progression and metastasis through macrophage reprogramming in the tumor microenvironment. STATEMENT OF SIGNIFICANCEThis study established the dual role of axon guidance molecule, SEMA3D, in the malignant transformation of pancreatic epithelial cells and of nerve-derived SEMA3D in PDA progression and metastasis. It revealed macrophage reprogramming as the mechanism underlying bothroles. Together, this research elucidated how inflammatory responses promote invasive PDA progression and metastasis through an oncogenic process.

cancer biology↗