Expression of FGF‐2/FGFR‐1 in normal mucosa, salivary gland, preneoplastic, and neoplastic lesions of the oral cavity

TGF-β3 from fibroblasts promotes necrotising sialometaplasia by suppressing salivary gland cell proliferation and inducing squamous metaplasia

Necrotising sialometaplasia (NSM) is a non-neoplastic lesion mainly arising in the minor salivary glands of the oral cavity. In the clinical features, NSM shows swelling with or without ulceration, and can mimic a malignant disease such as squamous cell carcinoma. Histopathologically, NSM usually shows the lobular architecture that is observed in the salivary glands. Additionally, acinar infarction and squamous metaplasia of salivary ducts and acini are observable. The aetiology of this lesion remains unknown, although it has a characteristic feature that sometimes requires clinical and histopathological differentiation from malignancy. In this study, we investigated upregulated genes in NSM compared with normal salivary glands, and focused on the TGF-β3 (TGFB3) gene. The results of the histopathological studies clarified that fibroblasts surrounding the lesion express TGF-β3. Moreover, in vitro studies using mouse salivary gland organoids revealed that TGF-β3 suppressed salivary gland cell proliferation and induced squamous metaplasia. We demonstrated a possible aetiology of NSM by concluding that increased TGF-β3 expression during wound healing or tissue regeneration played a critical role in cell proliferation and metaplasia. © 2024 The Pathological Society of Great Britain and Ireland.

A novel intronic circular RNA circFGFR1int2 up-regulates FGFR1 by recruiting transcriptional activators P65/FUS and suppressing miR-4687-5p to promote prostate cancer progression

Fibroblast growth factor receptor 1 (FGFR1) is a core component of the FGFs/FGFR pathway that activates multiple signalling pathways, including ERK1/2, PI3K/AKT, PLCγ, and NF-κB. Aberrant expression of FGFR1 due to gene amplification, chromosome rearrangement, point mutation, and epigenetic deregulations, have been reported in various cancers. FGFR1 overexpression has also been reported in prostate cancer (PCa), but the underlining mechanisms are not clear. Here we report a novel circular RNA, circFGFR1int2, derived from intron 2 of FGFR1 gene, which is overexpressed in PCa and associated with tumor progression. Importantly, we show that circFGFR1int2 facilitates FGFR1 transcription by recruiting transcription activators P65/FUS and by interacting with FGFR1 promoter. Moreover, we show that circFGFR1int2 suppresses post-transcriptional inhibitory effects of miR-4687-5p on FGFR1 mRNA. These mechanisms synergistically promote PCa cell growth, migration, and invasion. Overexpression of circFGFR1int2 is significantly correlated with higher tumor grade, Gleason score, and PSA level, and is a significant unfavorable prognosticator for CRPC-free survival (CFS) (RR = 3.277, 95% confidence interval: 1.192-9.009; P = 0.021). These findings unravelled novel mechanisms controlling FGFR1 gene expression by intronic circRNA and its potential clinicopathological utility as a diagnostic or therapeutic target.

Plumbagin Inhibits Proliferation, Migration, and Invasion of Retinal Pigment Epithelial Cells Induced by FGF-2

Proliferative vitreoretinopathy (PVR) is a serious ophthalmic disease and characterized by the formation of proliferative membranes by retinal pigment epithelial (RPE) cells. In PVR, the contraction and traction of the fibrocellular membranes cause retinal detachment, which can cause reduction surgery for retinal detachment to fail. Fibroblast growth factor-2 (FGF-2) causes RPE cells to form extracellular matrix (ECM), promotes chemotaxis, mitosis, and positively promotes the disease process of PVR. Plumbagin (PLB) is a plant small molecule naphthoquinone compound. It has the functions in anti-tumor, anti-inflammatory, inhibit proliferation. We tried to investigate the possible effects of PLB on the biological behavior of ARPE-19 cells induced by FGF-2 and its underlying mechanisms. Our study confirmed that proliferation, migration, and invasion of ARPE-19 cells induced by FGF-2 (10 ng/ml) were significantly inhibited by PLB. PLB also significantly inhibits the expression of MMP-2/-9, collagen I Alpha 1 (Col1A1), collagen IV Alpha 1 (Col4A1), collagen VI Alpha 1 (Col6A1), and the phosphorylation of FGF receptor (FGFR)-1, FGFR-2, ERK, p38, JNK of FGF-2-induced ARPE-19 cells. In summary, PLB inhibits FGF-2-stimulated proliferation, migration, and invasion of ARPE-19 cells, which may take place through inhibiting the expression of MMP-2/-9, Col1A1, Col4A1, Col6A1, and the mitogen-activated protein kinase (MAPK) pathway. PLB may have a preventive effect on proliferation, migration, and invasion of FGF-2-induced ARPE-19 cells.

Fibroblast growth factor-2 and interleukin-4 synergistically induce eotaxin-1 expression in adipose tissue-derived stromal cells

The relationships between eosinophils and adipose tissues are involved in metabolic homeostasis. Eotaxin is a chemokine with potent effects on eosinophil migration. To clarify the mechanisms of eotaxin expression in adipose tissues, we examined the effects of fibroblast growth factor-2 (FGF-2) and interleukin-4 (IL-4) stimulation on eotaxin expression in adipose tissue-derived stromal cells (ASCs), a type of adipocyte progenitor, in vitro. ASCs expressed eotaxin-1 and did not express eotaxin-2 or -3. Eotaxin-1 expression was increased in a concentration-dependent manner following FGF-2 treatment. Additionally, ASCs expressed FGF receptor-1 (FGFR-1) and did not express FGFR-2, -3, or -4. Eotaxin-1 expression was inhibited in cells treated with the FGFR tyrosine kinase inhibitor and extracellular signal-regulated kinase (ERK) inhibitor U0126, even in the presence of FGF-2. Moreover, eotaxin-1 expression was synergistically enhanced by combined treatment with FGF-2 and IL-4 and inhibited in the presence of U0126. Eotaxin-1 expression induced by FGF-2 and IL-4 was involved in ERK activation via FGFR-1 in ASCs. Upregulation of eotaxin expression in adipose tissues could increase eosinophil migration, thereby inducing IL-4 secretion and activation of alternative macrophages and improving glucose homeostasis. These findings provide insights into the mechanisms through which eotaxin mediates metabolic homeostasis in adipose tissues and eosinophils.