1. [Gly14]-humanin restores cathepsin D function via FPRL1 and promotes autophagic degradation of Ox-LDL in HUVECs
Huihui Liu, Yue Feng, Fen Wang, Yanlin Zhang, Yu Ding, Chunfeng Liu, Yutian Zou Nutr Metab Cardiovasc Dis . 2020 Nov 27;30(12):2406-2416. doi: 10.1016/j.numecd.2020.07.022.
Background and aim:Abnormal aggregation of oxidized low-density lipoprotein (Ox-LDL) in vascular endothelial cells (VECs) is one of the major pathological changes in atherosclerotic lesions. Our research aimed to assess the mechanism of humanin (HN) in promoting autophagic degradation of Ox-LDL in HUVECs.Methods and results:Flow cytometry and lipid quantitation results showed that Ox-LDL caused lipid and cholesterol accumulation in HUVECs. Western blot results showed that Ox-LDL increased the expression of autophagy-related proteins P62 and LC3-II in a concentration-dependent manner. The cathepsin D activity assay showed that Ox-LDL inhibited the function of cathepsin D. HNG pretreatment reduced lipid and cholesterol aggregation in HUVECs induced by Ox-LDL, increased LC3-II protein level, decreased P62 protein content, and reversed Ox-LDL-induced cathepsin D functional impairment. Inhibition of the FPRL1 pathway by FPRL1 siRNA or the FPRL1-specific inhibitor Boc-MLF blocked all HNG's protective effects. These results indicate that HNG could restore cathepsin D activity and protein level in HUVECs to repair lysosomal functional damage induced by Ox-LDL, further repairing Ox-LDL-induced autophagic damage in HUVECs.Conclusion:HNG restores the activity of Ox-LDL-induced damaged lysosomal enzyme cathepsin D through its membrane protein receptor FPRL1 to promote autophagic degradation of Ox-LDL in HUVECs.
2. The formyl peptide receptor agonist FPRa14 induces differentiation of Neuro2a mouse neuroblastoma cells into multiple distinct morphologies which can be specifically inhibited with FPR antagonists and FPR knockdown using siRNA
Michael S Howe, Nathaniel G N Milton, Peter J G Cussell, Margarita Gomez Escalada, Andrew W J Paterson, Thomas A Illingworth PLoS One . 2019 Jun 6;14(6):e0217815. doi: 10.1371/journal.pone.0217815.
The N-formyl peptide receptors (FPRs) have been identified within neuronal tissues and may serve as yet undetermined functions within the nervous system. The FPRs have been implicated in the progression and invasiveness of neuroblastoma and other cancers. In this study the effects of the synthetic FPR agonist FPRa14, FPR antagonists and FPR knockdown using siRNA on mouse neuroblastoma neuro2a (N2a) cell differentiation plus toxicity were examined. The FPRa14 (1-10μM) was found to induce a significant dose-dependent differentiation response in mouse neuroblastoma N2a cells. Interestingly, three distinct differentiated morphologies were observed, with two non-archetypal forms observed at the higher FPRa14 concentrations. These three forms were also observed in the human neuroblastoma cell-lines IMR-32 and SH-SY5Y when exposed to 100μM FPRa14. In N2a cells combined knockdown of FPR1 and FPR2 using siRNA inhibited the differentiation response to FPRa14, suggesting involvement of both receptor subtypes. Pre-incubating N2a cultures with the FPR1 antagonists Boc-MLF and cyclosporin H significantly reduced FPRa14-induced differentiation to near baseline levels. Meanwhile, the FPR2 antagonist WRW4 had no significant effect on FPRa14-induced N2a differentiation. These results suggest that the N2a differentiation response observed has an FPR1-dependent component. Toxicity of FPRa14 was only observed at higher concentrations. All three antagonists used blocked FPRa14-induced toxicity, whilst only siRNA knockdown of FPR2 reduced toxicity. This suggests that the toxicity and differentiation involve different mechanisms. The demonstration of neuronal differentiation mediated via FPRs in this study represents a significant finding and suggests a role for FPRs in the CNS. This finding could potentially lead to novel therapies for a range of neurological conditions including neuroblastoma, Alzheimer's disease, Parkinson's disease and neuropathic pain. Furthermore, this could represent a potential avenue for neuronal regeneration therapies.
3. Polymorphism of formyl peptide receptor 1 (FPR1) reduces the therapeutic efficiency and antitumor immunity after neoadjuvant chemoradiotherapy (CCRT) treatment in locally advanced rectal cancer
Tsung-Wei Chen, Kevin Chih-Yang Huang, Shu-Fen Chiang, William Tzu-Liang Chen, K S Clifford Chao, Tao-Wei Ke Cancer Immunol Immunother . 2021 Oct;70(10):2937-2950. doi: 10.1007/s00262-021-02894-8.
Immunosurveillance and immunoscavenging prompted by preoperative chemoradiotherapy (CCRT) may contribute to improve local control and increase survival outcomes for patients with locally advanced rectal cancer (LARC). In this study, we investigated several genotypes of pattern recognition receptors (PRRs) and their impact on therapeutic efficacy in LARC patients treated with CCRT. We found that homozygosis of formyl peptide receptor 1 (FPR1) (E346A/rs867228) was associated with reduced 5-year overall survival (OS) by Kaplan-Meier analysis (62% vs. 81%, p = 0.014) and multivariate analysis [hazard ratio (HR) = 3.383, 95% CI = 1.374-10.239, p = 0.007]. Moreover, in an animal model, we discovered that the FPR1 antagonist, Boc-MLF (Boc-1), reduced CCRT therapeutic efficacy and decreased cytotoxic T cells and T effector memory cells after chemoradiotherapy treatment. Pharmacologic inhibition of FPR1 by Boc-1 decreased T lymphocyte migration to irradiated tumor cells. Therefore, these results revealed that the FPR1 genotype participates in CCRT-elicited anticancer immunity by reducing T lymphocytes migration and infiltration, and that the FPR1-E346A CC genotype can be considered an independent biomarker for chemo- and radiotherapy outcomes.
