Suppressing STAT3 activation impairs bone formation during maxillary expansion and relapse

Abstract Objectives The mid-palatal expansion technique is commonly used to correct maxillary constriction in dental clinics. However, there is a tendency for it to relapse, and the key molecules responsible for modulating bone formation remain elusive. Thus, this study aimed to investigate whether signal transducer and activator of transcription 3 (STAT3) activation contributes to osteoblast-mediated bone formation during palatal expansion and relapse. Methodology In total, 30 male Wistar rats were randomly allocated into Ctrl (control), E (expansion only), and E+Stattic (expansion plus STAT3-inhibitor, Stattic) groups. Micro-computed tomography, micromorphology staining, and immunohistochemistry of the mid-palatal suture were performed on days 7 and 14. In vitro cyclic tensile stress (10% magnitude, 0.5 Hz frequency, and 24 h duration) was applied to rat primary osteoblasts and Stattic was administered for STAT3 inhibition. The role of STAT3 in mechanical loading-induced osteoblasts was confirmed by alkaline phosphatase (ALP), alizarin red staining, and western blots. Results The E group showed greater arch width than the E+Stattic group after expansion. The differences between the two groups remained significant after relapse. We found active bone formation in the E group with increased expression of ALP, COL-I, and Runx2, although the expression of osteogenesis-related factors was downregulated in the E+stattic group. After STAT3 inhibition, expansive force-induced bone resorption was attenuated, as TRAP staining demonstrated. Furthermore, the administration of Stattic in vitro partially suppressed tensile stress-enhanced osteogenic markers in osteoblasts. Conclusions STAT3 inactivation reduced osteoblast-mediated bone formation during palatal expansion and post-expansion relapse, thus it may be a potential therapeutic target to treat force-induced bone formation.

Effects of moxibustion on the P2X7R/STAT3/VEGF pathway in rats with colitis-associated colon cancer / 针灸推拿医学（英文版）

Objective: To observe the effects of herb-partitioned moxibustion and ginger-partitioned moxibustion on the growth of colon tumors in rats with colitis-associated colon cancer (CACC), and explore the mechanism of moxibustion intervening CACC through the purinergic receptor P2X ligand-gated ion channel 7 (P2X7R)/signal transducer and activator of transcription 3 (STAT3)/vascular endothelial growth factor (VEGF) pathway. Methods: A total of 26 male Sprague-Dawley rats were selected. According to the random number table method, 6 rats were selected as the normal group. The remaining 20 rats were injected intraperitoneally with azoxymethane (AOM) combined with oral dextran sodium sulfate (DSS) to prepare the CACC model. After the model was successfully established, 2 rats were randomly selected for model identification. The remaining 18 rats which were successfully modeled were randomly divided into a model group, a herb-partitioned moxibustion group and a ginger-partitioned moxibustion group, with 6 rats in each group. Moxibustion intervention was performed in the herb-partitioned moxibustion group and the ginger-partitioned moxibustion group at Qihai (CV 6) and bilateral Tianshu (ST 25). Moxibustion was performed twice at each point each time, once a day, at a 1-day interval after 6 consecutive interventions, for a total of 30 interventions. After intervention, the colon tumor load, pathological change and histopathological score were observed. Immunohistochemistry was used to detect the expressions of VEGF, P2X7R, phospho-STAT3 (p-STAT3), and nuclear factor-kappa B p65 (NF-κB p65) proteins in rat colon tissue. Western blot was used to detect the levels of p-STAT3 and NF-κB p65 proteins in rat colon tissue. Results: Compared with the normal group, the colon tumor load and histopathological score in the model group were significantly increased (both P<0.001), and different grades of dysplasia were observed in colon tissue from the model group, reaching the degree of adenocarcinoma; the expression level of P2X7R protein in colon tissue was significantly decreased (P<0.001), and the expression levels of p-STAT3, NF-κB p65 and VEGF proteins were significantly increased (all P<0.001) in the model group. Compared with the model group, the colon tumor load, colon histopathological score and the levels of p-STAT3, NF-κB p65 and VEGF proteins in colon tissue were significantly decreased (all P<0.05) in the herb-partitioned moxibustion group and the ginger-partitioned moxibustion group while the expression levels of P2X7R protein in colon tissue were significantly increased (both P<0.05). Conclusion: Both herb-partitioned moxibustion and ginger-partitioned moxibustion can reduce the colon tumor load in CACC rats and delay the progression of colon adenomas. The mechanism may be mediated by the P2X7R/STAT3 pathway to inhibit STAT3 phosphorylation, thereby reducing VEGF protein expression.

15-Deoxy-delta12,14-PGJ2inhibits IL-6-induced Stat3 phosphorylation in lymphocytes

15-deoxy-delta12,14-PGJ2(15d-PGJ2) is a natural ligand that activates the peroxisome proliferators-activated receptor (PPAR) gamma, a member of nuclear receptor family implicated in regulation of lipid metabolism and adipocyte differentiation. Recent studies have shown that 15d-PGJ2 is the potent anti-inflammatory agent functioning via PPARgamma-dependent and -independent mechanisms. Most postulated mechanisms for anti-inflammatory action of PPARgamma agonists are involved in inhibiting NF-kappaB signaling pathway. We examined the possibility that IL-6 signaling via the Jak-Stat pathway is modulated by 15d-PGJ2 in lymphocytes and also examined whether the inhibition of IL-6 signaling is dependent of PPARgamma. 15d-PGJ2 blocked IL-6 induced Stat1 and Stat3 activation in primary human lymphocytes, Jurkat cells and immortalized rheumatoid arthritis B cells. Inhibition of IL-6 signaling was induced rapidly within 15 min after treatment of 15d-PGJ2. Other PPARgamma-agonists, such as troglitazone and ciglitazone, did not inhibit IL-6 signaling, indicating that 15d-PGJ2 affect the IL-6-induced Jak-Stat signaling pathway via PPARgamma-independent mechanism. Although cycloheximide reversed 15d-PGJ2-mediated inhibition of Stat3 activation, actinomycin D had no effect on 15d-PGJ2-mediated inhibition of IL-6 signaling, indicating that inhibition of IL-6 signaling occur independent of de novo gene expression. These results show that 15d-PGJ2 specifically inhibit Jak-Stat signaling pathway in lymphocytes, and suggest that 15d-PGJ2 may regulate inflammatory reactions through the modulation of different signaling pathway other than NF-kappaB in lymphocytes.

The Clinical Significance of STAT3 and STAT5 Activation in Renal Cell Carcinoma / 대한비뇨기과학회지

PURPOSE: Cytokines, hormones and growth factors use signal transducers and activators of transcription (STAT) signaling pathways to control various biological responses, including development, differentiation, cell proliferation and survival. STAT3 and 5 help promote cell cycle progression and cellular transformation and prevent apoptosis. In this research, the presence of STAT3 and STAT5 activation and their association with pathological features and clinical outcome in renal cell carcinoma cases were studied. MATERIALS AND METHODS: Using immunohistochemistry with rabbit polyclonal anti-STAT3 and STAT5 antibodies, forty-eight paraffin-embedded renal cell carcinoma specimens were examined for the activation status of STAT3 and STAT5. Cells of which 10% or more were left with a dark brown stains in the nucleus were regarded as positive tumor cells. The activation status of STAT3 and STAT5 were compared with the clinicopathological variables. RESULTS: Significant associations of STAT3 activation with tumor size, T-stage, distant metastases and low survival rate were observed (p<0.05); and in STAT5, significant associations with distant metastases and low survival rate were observed (p<0.05). CONCLUSIONS: The results of this study strongly suggest that the activation of STAT3 and STAT5 contribute to the development and progression of the renal cell carcinoma.

EXPRESSION OF STAT3 PROTEIN IN THE RETINA OF HAMSTER DURING EARLY POSTNATAL DEVELOPMENT / 解剖学报

Objective To investigate the expression and distribution of STAT3 in the retina during the early development of postnatal hamster. Methods Immunocytochemical method and Western blot analysis were used. Results The expression of STAT3 was found in all layers of the retina in all newborn hamsters,most pronounced in the ganglion cell layer(GCL),the inner plexiform layer(IPL)and the inner area of neuroblastic layer(NBL).With the development,the STAT3 immunoreactivity was gradually restricted in the cytoplasm and the nucleus of the retinal ganglion cells.The result of the Western blot showed that the STAT3 was highly expressed in the first week of postnatal development and then reduced gradually till the lowest point in the adulthood.Conclusion The expression of STAT3 protein may be closely related to the early development of the retina in the postnatal hamster.