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Objective:To investigate the effects of myeloid differentiation protein-2 (MD-2) on paclitaxel resistance cells in triple negative breast cancer (TNBC) through EGFR signaling pathway.Methods:Immunohistochemical method was used to detect the expression of MD-2 in cancer tissue and adjacent tissue of TNBC patients, and the relationship between MD-2 expression and clinicopathological parameters of patients was analyzed. The TNBC paclitaxel-resistant cell line was constructed and MD-2 expression in cells was interfered. Cell invasion was detected by Transwell, and cell apoptosis was detected by flow cytometry. The signaling pathways regulated by MD-2 were screened by transcriptome sequencing and verified by Western blot.Results:The expression of MD-2 was significantly enhanced in cancer tissues relative to adjacent tissues. High expression of MD-2 was closely related to clinical stage, tumor size, tumor recurrence and metastasis ( χ2=4.50, P=0.032; χ2=2.55, P=0.011; χ2=4.40, P=0.036). In cell experiments, compared with normal breast cells, the expression of MD-2 in TNBC cell lines was significantly enhanced. Compared with sh-NC group (100±11.52) (6.81±0.57), knockdown of MD-2 could inhibit the invasion (61.44±6.78) ( t=4.99, P=0.008) but promote apoptosis (15.19±1.06) ( t=12.06, P<0.001) of paclitaxel resistant TNBC cells. Transcriptome sequencing and Western blot results showed that MD-2 mainly affects the biological behavior of TNBC cells by regulating the EGFR signaling pathway. Conclusions:MD-2 promoted TNBC cell invasion and paclitaxel resistance, which may be achieved by affecting the EGFR signaling pathway. MD-2 is expected to become an effective target in TNBC treatment.
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Objective To explore the effect of toll-like receptor 4 (TLR4), myeloid differentiation protein-2 (MD2), and stromal interaction molecular 1 (STIM1) for regulating human vascular endothelial calcium overload injury and inflammatory reaction induced by bacterial endotoxin (LPS).Methods Human umbilical vein endothelial cells (HUVECs) were cultured in Dulbecco's modification of Eagle's medium (DMEM). ① The levels of TLR4, MD2 and nuclear factor-κB (NF-κB) were detected by reverse transcriotion-polymerase chain reaction (RT-PCR) before and 0.5, 1, 6, 12, 24 hours after LPS stimulation. ② Intracellular calcium peak level was detected by confocal following probe fluo-3 AM loading in HUVEC cells induced with LPS and transfected by psiSTIM or psiTLR. ③ MD2, STIM1 or NF-κB protein level was detected by immunoprecipitation (IP) and immuno-blotting in HUVEC cells which were transfected by TLR4 inhibited expression (psiTLR) for 12 hours and followed by LPS stimulation for 6 hours. ④ HUVEC cells were randomly divided into 6 groups: control group, LPS group, PDTC 0.1 mg/L group, PDTC 1 mg/L group, psiTLR 1 h group and psiTLR 12 h group. Tumor necrosis factor-α (TNF-α) and interleukin-6 (IL-6) were detected by enzyme linked immunosorbent assay (ELISA) in supernatant. The mRNA levels of STIM1 and NF-κB were detected by RT-PCR.Results ① The mRNA levels of TLR4, MD2, and NF-κB gradually increased after LPS induction and peaked at 6 hours (2-ΔΔCt: 23.52±2.88, 17.43±3.43, 18.13±2.99, respectively), which were statistically significant before the stimulation with LPS (2-ΔΔCt: 7.02±2.81, 5.19±3.22, 8.11±1.42, allP < 0.05). ② Extracellular calcium influx in LPS group was increased significantly higher than control group (nmol/L: 108.13±22.33 vs. 41.57±13.19, P < 0.01). Extracellular calcium influx in psiSTIM+LPS group (nmol/L: 62.61±14.12 vs. 108.13±22.33,P < 0.05) and psiTLR+LPS group (nmol/L: 50.78±8.05 vs. 109.43±20.21,P < 0.01) were both suppressed as compared with LPS group. While extracellular calcium peak level in psiTLR+psiSTIM+LPS group further decreased (nmol/L: 39.31±6.42 vs. 109.43±20.21,P < 0.01). ③ MD2 protein but not STIM1 or NF-κB can be detected in anti-TLR4 precipitates in control (ctrl-) by immunoprecipitation. MD2 protein level increased in anti-TLR4 precipitates in LPS group (ctrl+) and was suppressed in TLR4 inhibiting group (psiTLR). ④ The levels of TNF-α in PDTC 1mg/L group were significantly lower than those of LPS group (ng/L: 0.60±0.24 vs. 1.77±0.66,P < 0.01). The levels of IL-6 in PDTC 0.1 mg/L, 1 mg/L group and psiTLR 12 h group decreased significantly lower than that of LPS group (ng/L: 232.10±63.54, 134.32±37.23, 284.23±56.14 vs. 510.22±89.23, allP < 0.05). Compared to LPS group, the mRNA levels of NF-κB and STIM1 were obviously inhibited in PDTC1 mg/L group and psiTLR 12 h group [NF-κB mRNA (2-ΔΔCt): 17.22±2.35, 13.24±3.54 vs. 30.16±2.06; STIM1 mRNA (2-ΔΔCt): 12.57±2.43, 12.21±2.46 vs. 25.12±2.02, allP < 0.05]. Conclusions TLR4, MD2, NF-κB signal and SOC calcium channel STIM1 mediate LPS induced-calcium influx and inflammatory mediators level in HUVEC cells. Extracellular calcium overload and inflammatory response by endotoxin induction can be effectively inhibited by down-regulation of TLR4, NF-κB and/or STIM1.
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Objective To observe effects of the antisense genes of Toll-like receptor 4 (TLR4 ) and myeloid differentiation protein-2 (MD2) on the activation of NF-?B in alveolar typeⅡepithelial cells (ATⅡcells) induced by lipopolysaccharide (LPS). Methods Cultured ATⅡcells were randomized to normal cells (control) group,LPS group,LPS+empty vector group,LPS+TLR4 antisense gene group,LPS+MD2 antisense gene group,LPS+TLR4-MD2 antisense gene group. The expressions of TLR4 and MD2 mRNA and protein in ATⅡcells were detected by Northern blotting and Western blotting respectively. The activity of NF-?B in ATⅡcells was measured with electrophoretic mobility shift assay (EMSA). The TNF-? and IL-6 concentrations in the supernatant of cultured ATⅡcells were tested with ELISA.Results Compared with control groups,the expressions of TLR4 and MD2 mRNA and protein,the NF-?? activity,the levels of TNF-? and IL-6 were increased remarkably in LPS group and LPS+empty vector group (P
ABSTRACT
Myeloid differentiation protein-2(MD-2)can separately and simultaneously bind lipopolysaccharide(LPS)and toll-like receptor 4(TLR4)has been shown to play critical roles in mediated recognition responses to LPS by TLR4 and signal transduction induced by LPS.MD-2 can be bound by LPS,not TLR4.The cells have no responsiveness or weak responsiveness to LPS without MD-2.MD-2 can be secreted into blood plasma,formed soluble MD-2 and remotely regulated cells that contained TLR4 without MD-2.MD-2 has been shown to play important roles in endotoxin signal transduction.MD-2 is a small molecular,short nucleic acid fragment,easily regulated should become a new potential anti-inflammatory target.