Targeting Soluble Epoxide Hydrolase with TPPU Alleviates Irradiation‐Induced Hyposalivation in Mice via Preventing Apoptosis and Microcirculation Disturbance

Role of soluble epoxide hydrolase in the abnormal activation of fibroblast-like synoviocytes from patients with rheumatoid arthritis

Rheumatoid arthritis (RA) is an autoimmune disease characterized by enigmatic pathogenesis. Polyunsaturated fatty acids (PUFAs) are implicated in RA's development and progression, yet their exact mechanisms of influence are not fully understood. Soluble epoxide hydrolase (sEH) is an enzyme that metabolizes anti-inflammatory epoxy fatty acids (EpFAs), derivatives of PUFAs. In this study, we report elevated sEH expression in the joints of CIA (collagen-induced arthritis) rats, concomitant with diminished levels of two significant EpFAs. Additionally, increased sEH expression was detected in both the synovium of CIA rats and in the synovium and fibroblast-like synoviocytes (FLS) of RA patients. The sEH inhibitor TPPU attenuated the migration and invasion capabilities of FLS derived from RA patients and to reduce the secretion of inflammatory factors by these cells. Our findings indicate a pivotal role for sEH in RA pathogenesis and suggest that sEH inhibitors offer a promising new therapeutic strategy for managing RA.

TPPU inhibits inflammation-induced excessive autophagy to restore the osteogenic differentiation potential of stem cells and improves alveolar ridge preservation

Inflammation-induced autophagy is a double-edged sword. Dysfunction of autophagy impairs the differentiation capacity of mesenchymal stem cells and enhances inflammation-induced bone loss. Tooth extraction with periodontal and/or endodontic lesions exacerbates horizontal and vertical resorption of alveolar bone during the healing period. Alveolar socket preservation (ASP) procedure following tooth extraction has important clinical implications for future prosthodontic treatments. Studies have shown that epoxyeicosatrienoic acids (EETs) have significant anti-inflammatory effects and participate in autophagy. However, whether EETs can minimize alveolar bone resorption and contribute to ASP by regulating autophagy levels under inflammatory conditions remain elusive. Here, we figured out that LPS-induced inflammatory conditions increased the inflammatory cytokine and inhibited osteogenic differentiation of human dental pulp stem cells (hDPSCs), and led to excessive autophagy of hDPSCs. Moreover, we identified that increased EETs levels using TPPU, a soluble epoxide hydrolase inhibitor, reversed these negative outcomes. We further demonstrated the potential of TPPU to promote early healing of extraction sockets and ASP, and speculated that it was related to autophagy. Taken together, these results suggest that targeting inhibition of soluble epoxide hydrolase using TPPU plays a protective role in the differentiation and autophagy of mesenchymal stem cells and provides potential feasibility for applying TPPU for ASP, especially under inflammatory conditions.

Targeting soluble epoxide hydrolase promotes osteogenic-angiogenic coupling via activating SLIT3/HIF-1α signalling pathway

Type H vessels have recently been identified to modulate osteogenesis. Epoxyeicostrioleic acids (EETs) have an essential contribution to vascular homeostasis. However, whether increased EETs with soluble epoxide hydrolase (sEH) inhibitor TPPU enhance the coupling of angiogenesis and osteogenesis remains largely unknown. The effects of TPPU on cross-talk between co-cultured human umbilical vein endothelial cells (HUVECs) and human dental pulp stem cells (hDPSCs), and on long bone growth and calvarial defect repair in mice were investigated in vitro and in vivo. TPPU enhanced osteogenic differentiation of co-cultured HUVECs and hDPSCs in vitro and increased type H vessels, and long bone growth and bone repair of calvarial defect. Mechanistically, TPPU promoted cell proliferation and angiogenesis, reclined cell apoptosis, and significantly increased CD31^hi EMCN^hi endothelial cells (ECs) and SLIT3 and HIF-1α expression levels in co-cultured HUVECs and hDPSCs. Knockdown of Slit3 in hDPSCs or Hif-1α in HUVECs impaired the formation of CD31^hi EMCN^hi ECs and reversed TPPU-induced osteogenesis. We defined a previously unidentified effect of TPPU coupling angiogenesis and osteogenesis. TPPU induced type H vessels by upregulating the expression of hDPSCs-derived SLIT3, which resulted in the activation of ROBO1/YAP1/HIF-1α signalling pathway in ECs. Targeting metabolic pathways of EETs represents a new strategy to couple osteogenesis and angiogenesis, sEH is a promising therapeutic target for bone regeneration and repair.

LIS1 interacts with CLIP170 to promote tumor growth and metastasis via the Cdc42 signaling pathway in salivary gland adenoid cystic carcinoma

Salivary gland adenoid cystic carcinoma (SACC) is one of the most common malignant tumors, with high aggressive potential in the oral and maxillofacial regions. Lissencephaly 1 (LIS1) is a microtubule-organizing center-associated protein that regulates the polymerization and stability of microtubules by mediating the motor function of dynein. Recent studies have suggested that LIS1 plays a potential role in the malignant development of tumors, such as in mitosis and migration. However, the role of LIS1 in SACC development and its related molecular mechanisms remain unclear. Thus, the effects of LIS1 on the proliferation, apoptosis, invasion and metastasis of SACC were studied, in vivo and in vitro. The results of immunohistochemical staining showed that LIS1 was highly expressed in SACC tissues, and its expression level was associated with malignant progression. In vitro, the results of CCK-8, TUNEL, wound healing and Transwell assays demonstrated that LIS1 promotes proliferation, inhibits apoptosis, and enhances the migration and invasion of SACC-LM cells. In vivo, knockdown of LIS1 effectively suppressed the growth of subcutaneous tumors in a mouse xenograft and distant metastasis of tumor cells in the metastasis model. The co-immunoprecipitation, immunofluorescence and western blot results also revealed that LIS1 binds to cytoplasmic linker protein 170 (CLIP170) to form a protein complex (LIS1/CLIP170), which activates the cell division control protein 42 homolog (Cdc42) signaling pathway to modulate the proliferation and anti-apoptosis of tumor cells, and enhanced invasion and metastasis by regulating the formation of invadopodia and the expression of MMPs in SACC-LM cells. Therefore, the present study demonstrated that LIS1 is a cancer promoter in SACC, and the molecular mechanism of the LIS1/CLIP170/Cdc42 signaling pathway is involved in the malignant progression, which offers a promising strategy for targeted therapy of SACC.

CCL25/CCR9 interaction promotes the malignant behavior of salivary adenoid cystic carcinoma via the PI3K/AKT signaling pathway

Background

CC chemokine receptor 9 (CCR9), an organ-specific chemokine receptor, interacts with its exclusive ligand CCL25 to promote tumor proliferation and metastasis. However, the effect of CCR9 on salivary adenoid cystic carcinoma (SACC) malignant behavior remains unknown. This study aimed to investigate the specific molecular mechanism by which CCR9/CCL25 modulates malignant progression in SACC.

Methods

Immunohistochemistry staining and RT-qPCR analyses were performed to detect the correlation of CCR9 expression and tumor progression-associated markers in SACC. In vitro, SACC cell proliferation and apoptosis were evaluated using Cell Counting Kit-8 and colon formation, and cell migration and invasion were detected by wound healing and transwell assays. Vercirnon was used as an inhibitor of CCR9, and LY294002 was used as an inhibitor of the PI3K/AKT pathway in this study. Western blot and RT-qPCR assays were carried out to measure the downstream factors of the interaction of CCL25 and CCR9. The effect of CCL25 on the development of SACC in vivo was examined by a xenograft tumor model in nude mice following CCL25, Vercirnon and LY294002 treatment.

Results

CCR9 was highly expressed in SACC compared with adjacent salivary gland tissues, and its level was associated with tumor proliferation and metastases. CCL25 enhanced cell proliferation, migration, and invasion through its interaction with CCR9 and exerted an antiapoptotic effect on SACC cells. Targeting CCR9 via Vercirnon significantly reduced the phosphorylation level of AKT induced by CCL25. CCL25/CCR9 could activate its downstream factors through the PI3K/AKT signaling pathway, such as cyclin D1, BCL2 and SLUG, thus promoting SACC cell proliferation, antiapoptosis, invasion and metastasis. The in vivo data from the xenograft mouse models further proved that CCL25 administration promoted malignant tumor progression by activating the PI3K/AKT pathway.

Conclusion

The interaction of CCL25 and CCR9 promotes tumor growth and metastasis in SACC by activating the PI3K/AKT signaling pathway, offering a promising strategy for SACC treatment.