High sodium chloride affects BMP-7 and 1α-hydroxylase levels through NCC and CLC-5 in NRK-52E cells.

A diet high in sodium chloride (NaCl) can affect renal function damage and increase urinary calcium excretion, leading to bone loss. in renal tubules, Na-Cl co-transporter (NCC) and chloride channel 5 (CLC-5) are involved in regulating urinary calcium excretion. In addition, some cytokines, such as Bone morphogenetic protein 7 (BMP-7) and 1α-hydroxylase, are synthesized by renal tubules, which target on bone and play important roles on bone metabolism. However, the specific mechanisms between NaCl and these ion channels or cytokines still need investigations from many aspects. This study, in culture normal rat renal tubular epithelial NRK-52E cells, showed that high concentrations of NaCl significantly inhibited the cell viability and increased the cell apoptosis. High concentration of NaCl reduce bone mineral density (BMD), as demonstrated by the significantly increased mRNA and protein levels of NCC and osteopontin (OPN), but decreased the levels of CLC-5, BMP-7, and 1α-hydroxylase. In addition, we found that ovariectomized (OVX) rats on a high-salt diet for 12 weeks had altered levels of these indices in the renal cortices. Moreover, the BMD in fourth and fifth lumbar vertebra (LV4 and 5) and femurs were significantly decreased and bone microstructure was destroyed of these rats. We also demonstrated that high concentration of NaCl enhanced the inhibition of these cytokines which is beneficial to increase BMD, induced by modulating ion channels NCC and CLC-5. In conclusion, our results indicate that high concentration of NaCl reduce BMD by regulating ion channels NCC and CLC-5.

Resveratrol protects MC3T3-E1 cells against cadmium-induced suppression of osteogenic differentiation by modulating the ERK1/2 and JNK pathways.

Resveratrol (RES) is a natural polyphenolic compound with a broad range of physiological and pharmacological properties. Previous studies have shown that RES also plays an important role in protecting and promoting early bone metabolism and differentiation. The accumulation of cadmium (Cd), one of the world's most poisonous substances, can inhibit skeletal growth and bone maturation, thus causing osteoporosis. However, whether RES can prevent the Cd-induced inhibition of osteogenic differentiation remains unknown. In this study, we found that RES promoted the early maturity of osteoblastic MC3T3-E1 cells, as demonstrated by the significantly increased mRNA and protein expression of a range of differentiation markers, including alkaline phosphatase (ALP), collagen 1 (COL1), bone morphogenetic protein-2 (BMP-2), and runt-related transcription factor 2 (RUNX2). In contrast, we found that cadmium chloride (CdCl2) inhibited the viability and osteogenic maturity of MC3T3-E1 cells. We also demonstrated that RES pretreatment for 30 min provided significant protection against Cd-induced apoptosis and attenuated the inhibition of osteogenic differentiation induced by Cd by modulating ERK1/2 and JNK signaling. In conclusion, our results indicate that RES is a potential femoral protectant that not only enhance the viability and early differentiation of osteoblasts, but also protect osteoblasts from cadmium damage.

Ginsenoside panaxatriol reverses TNBC paclitaxel resistance by inhibiting the IRAK1/NF-κB and ERK pathways.

BACKGROUND: Paclitaxel (PTX) resistance is a major obstacle in the treatment of triple-negative breast cancer (TNBC). Previously, we have reported that interleukin-1 receptor-associated kinase 1 (IRAK1) and its downstream pathways are associated with PTX resistance in TNBC cells. In this study, we sought to investigate the combination treatment of ginsenoside panaxatriol (GPT), one of the main active components in Panax ginseng, with PTX on viability and apoptosis of TNBC PTX resistant cells, and explore the role of IRAK1 mediated signaling pathways in the therapeutic effects. METHODS: CellTiter-Glo and colony formation assays were used to assess cell viability. Flow cytometry was used to analyze subG1 and apoptosis. Western blot was used to detect expressions of proteins involved in apoptosis and the IRAK1/NF-κB and ERK pathways. The mRNA expression of inflammatory cytokines, S100A7/8/9 and cancer stem cell (CSC)-related genes were examined by qPCR. Stem cells were identified by tumor sphere assay. Cell invasion ability was examined by transwell assay. RESULTS: We show that GPT inhibits MDA-MB-231 PTX resistant (MB231-PR) cell viability in a dose-dependent manner. When combined with PTX, GPT synergistically causes more cell death, induces subG1 accumulation and cell apoptosis. Besides, up-regulation of BAX/BCL-2 ratio, and down-regulation of MCL-1 are also observed. Moreover, this combination inhibits IRAK1, NF-κB and ERK1/2 activation, and leads to down-regulation of inflammatory cytokines (IL6, IL8, CXCL1, CCL2), S100A7/9 and CSC-related genes (OCT4, SOX2, NANOG, ALDH1, CD44) expression. In addition, the combination treatment suppresses MB231-PR cell invasion ability, and impairs tumor sphere growth both in MB231-PR and SUM159 PTX resistant (SUM159-PR) cells. CONCLUSION: Our study demonstrates that GPT can resensitize TNBC PTX resistant cells to PTX by inhibiting the IRAK1/NF-κB and ERK pathways and reducing stem cell characteristics.

Lead exposure inhibits osteoblastic differentiation and inactivates the canonical Wnt signal and recovery by icaritin in MC3T3-E1 subclone 14 cells.

Exposure to lead (Pb) poses a threat to human bone health, including changes in bone mineral composition and the inhibition of skeletal growth and bone maturation. However, little is known about how Pb directly affects osteoblasts. In this work, we found that sub-toxic Pb concentrations suppressed bone nodule formation and inhibited differentiation in MC3T3-E1 subclone 14 cells, as shown by decreased expression levels of the differentiation markers alkaline phosphatase (ALP), type 1 collagen (COL1), osteocalcin (OC), and runt-related transcription factor 2 (RUNX2). Moreover, Pb inactivated the canonical Wnt pathway by regulating key components, such as Wnt3a, Dkk-1, pGSK3ß, and ß-catenin. Icaritin (ICT), a hydrolytic product of icariin from the genus Epimedium, attenuates the inhibitory effect of Pb on osteoblastic differentiation, as well as activate the canonical Wnt signal pathway. Taken together, the results suggest ICT as a potential bone protectant that may be used to prevent bone damage caused by Pb and can activate the canonical Wnt signal pathway.