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Background Epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors (TKIs) are being wildly used as target therapy in non-small-cell lung cancer (NSCLC). However, NSCLC patients with wild-type EGFR and KRAS mutation are primary resistant to EGFR-TKIs such as gefitinib. Curcumin has been known as a potential therapeutic agent for several major human cancers. In this study, we investigated the effect of curcumin on the reversal of gefitinib resistance in NSCLC cells as well as their molecular bases. Methods H157 (wild-type EGFR and KARS mutation) and H1299 (wild-type EGFR and HRAS mutation) cells were treated with gefitinib or curcumin alone, or the two combination, and then cell viability, EGFR activity, expressions of Sp1 and Sp1-dependent proteins and receptor tyrosine kinases, markers of autophagy and apoptosis were examined by using CCK-8, colony formation, immunoblot, quantitative PCR, immunofluoscence, and flow cytometry assays. Also xenograft experiments were conduced to test the synergism of curcumin to gefitinib. Results Our results showed that curcumin significantly enhanced inhibitory effect of gefitinib on primary gefitinib-resistant NSCLC cell lines H157 and H1299. Combination treatment with curcumin and gefitinib markedly downregulated EGFR activity through suppressing Sp1 and blocking interaction of Sp1 and HADC1, and markedly suppressed receptor tyrosine kinases as well as ERK/MEK and AKT/S6K pathways in the resistant NSCLC cells. Meanwhile, combination treatment of curcumin and gefitinib caused dramatic autophagy induction, autophagic cell death and autophagy-mediated apoptosis, compared to curcumin or gefitinib treatment alone, as evidenced by the findings that curcumin and gefitinib combination treatment-produced synergistic growth inhibition and apoptosis activation can be reversed by pharmacological autophagy inhibitors (Baf A1 or 3-MA) or knockdown of Beclin-1 or ATG7, also can be partially returned by pan-caspase inhibitor (Z-VAD-FMK) in H157 and H1299 cells. Xenograft experiments in vivo yielded similar results. Conclusions These data indicate that the synergism of curcumin on gefitinib was autophagy dependent. Curcumin can be used as a sensitizer to enhance the efficacy of EGFR-TKIs and overcome the EGFR-TKI resistance in NSCLC patients with wild-type EGFR and/or KRAS mutation. Electronic supplementary material The online version of this article (10.1186/s13046-019-1234-8) contains supplementary material, which is available to authorized users.

Obstructive sleep apnea hypopnea syndrome, characterized by chronic intermittent hypoxia (CIH), is closely correlated with genioglossus dysfunction. CIH has been identified to mediate mitochondrial damage in genioglossus. It has been reported that endoplasmic reticulum stress (ERS) could be induced by mitochondrial dysfunction. This study aimed to investigate the role of ERS in CIH-induced genioglossus injury, as well as the possible intervention effect of adiponectin (Ad) supplement in rats.Forty-five male Wistar rats were randomly divided into three groups and submitted to room air (group A, n=15) as a control or CIH (groups B and C, n=15, respectively). Throughout the exposure period, intravenous Ad was given in group C; while intravenous normal saline was simultaneously given in groups A and B. After 35-day exposure, genioglossus samples were obtained from the pentobarbital-anaesthetized rats via surgical dissection, following blood sampling. Western blotting was applied to detect expressions of ERS signals and associated apoptotic pathways in genioglossus. Serum adiponectin levels were assessed via enzyme-linked immunosorbent assay (ELISA).Significant hypoadiponectinemia was revealed in group B only (P0.05). Compared to those in groups A and C, expressions of markers involved in ERS, such as glucose regulated protein 78 (GRP78), p-PERK, phosphorylated eukaryotic initiation factor 2a (p-eIF2a), phosphorylated inositol-requiring transmembrane kinase/endoribonuclease 1a (p-IRE1a), spliced X-Box binding protein 1 (XBP1s) and activating transcription factor 6 (ATF6), were significantly enhanced in group B (all P0.01); while no significant difference was shown between groups A and C (all P0.05). ERSassociated apoptotic pathways were remarkably activated in group B. The involved markers detected as the expression of CCAAT/enhancer binding protein homologous protein (CHOP), B-cell lymphoma/leukemia associatied X protein (BAX) and caspase-12 were significantly elevated (all P0.01). Transvenous adiponectin supplement improved the above CIHinduced pathological changes in group C.Beyond hypoadiponectinemia, CIH could enhance ERS and induce activation of ERS-associated apoptotic pathways in genioglossus, which could be significantly improved by adiponectin supplement.

Genioglossal dysfuntion takes an important role in pathogenesis of obstructive sleep apnea hypopnea syndrome (OSAHS) in which chronic intermittent hypoxia (CIH) is the major pathological origin. Recent studies have suggested genioglossal injury induced by CIH might be improved by adiponectin. The aim of this study was to investigate the effects of adiponectin on genioglossus contractile properties in rats exposed to CIH.Thirty-nine healthy male Wistar rats were randomly divided into three groups: normal control (NC), CIH and adiponectin supplement (CIH+Ad) with 13 rats in each. Rats in NC were kept breathing normal air, while rats in CIH and CIH+Ad experienced the same CIH environment eight hours per day for 35 successive days. Rats in CIH+Ad were given intravenous adiponectin of 10 µg twice a week for 30 successive days. Rats in the NC and CIH were injected with normal saline as a control. After 35 days' CIH exposure, the levels of serum adiponectin and genioglossus contractile properties were compared.Serum adiponectin level was significantly lower in CIH than in NC (1210 ng/ml vs. 2236 ng/ml). Serum adiponectin level in CIH+Ad (1844 ng/ml) was significantly higher than CIH but lower than NC. Twitch tension, time to peak tension, half relaxation time and tetanic tension were significantly lower in CIH than NC and improved in CIH+Ad. All mean tetanic fatigue indices decreased more rapidly in the first 20 seconds than during the subsequent 100 seconds. Tetanic fatigue indices in NC and CIH+Ad were significantly higher compared to CIH.CIH could lead to hypoadiponectinaemia, impaired genioglossus contractile properties and decreased fatigue resistance in rats. Such changes could be partially offset by supplementation of adiponectin.

Obstructive sleep apnea hypopnea syndrome (OSAHS) is regarded as a disease with strong genetic background and associated with hypoadiponectinemia. It is worthwhile to investigate the possible correlation between the single nucleotide polymorphisms (SNPs) in the adiponectin gene and OSAHS.With the TaqMan polymerase chain reaction (PCR) method, the SNPs at positions 45 and 276 in the adiponectin gene were determined in Chinese of Han nationality in Nanjing district consisting of 103 OSAHS patients (OSAHS group) and 67 normal controls (control group). The association of adiponectin genotype polymorphisms at positions 45 and 276 with OSAHS was analyzed.No evidence of a direct association was found between OSAHS and adiponectin genotype SNP at positions 45 and 276 (P0.05). However, compared with those OSAHS patients having G/T + T/T genotype at position 276, the OSAHS patients with G/G genotype showed a longer neck circumference, a prolonged duration of the longest apnea event, and an elevated level of blood cholesterol and low-density lipoprotein cholesterol (P0.05).No direct association was suggested between OSAHS and adiponectin genotype distribution at positions 45 and 276 in Chinese of Han nationality in Nanjing district. However, in OSAHS patients, those with adiponectin G/G genotype at position 276, seemed to have a higher potential risk in development of OSAHS than those having adiponectin SNP276 G/T + T/T genotype.

SR-A (class A macrophage scavenger receptor) is a transmembrane receptor that can bind many different ligands, including modified lipoproteins that are relevant to the development of vascular diseases. However, the precise endocytic pathways of SR-A/mediated ligands internalization are not fully characterized. In this study, we show that the SR-A/ligand complex can be endocytosed by both clathrin- and caveolae-dependent pathways. Internalizations of SR-A-lipoprotein (such as acLDL) complexes primarily go through clathrin-dependent endocytosis. In contrast, macrophage apoptosis triggered by SR-A-fucoidan internalization requires caveolae-dependent endocytosis. The caveolae-dependent process activates p38 kinase and JNK signaling, whereas the clathrin-mediated endocytosis elicits ERK signaling. Our results suggest that different SR-A endocytic pathways have distinct functional consequences due to the activation of different signaling cascades in macrophages.

Macrophage death in advanced atherosclerosis promotes plaque necrosis and destabilization. Involvement of autophagy in bulk degradation of cellular components has been recognized recently as an important mechanism for cell survival under endoplasmic reticulum (ER) stress. We previously found that the engagement of class A scavenger receptor (SR-A) triggered JNK-dependent apoptosis in ER-stressed macrophages. However, pro-apoptotic mechanisms mediated by SR-A are not fully understood. Therefore, we sought to see if SR-A mediated apoptosis was associated with autophagy in macrophages. Here, we showed that fucoidan inhibited microtubule-associated protein light chain 3-phospholipid conjugates (LC3-II) formation as well as the number of autophagosomes under ER stress. The inhibition of LC3-II formation was paralleled by the activation of the mTOR pathway, and the inhibition of mTOR allowed LC3-II induction in macrophages treated with thapsigargin plus fucoidan. Furthermore, apoptosis induced by fucoidan was prevented under ER stress by the mTOR inhibitor. We propose that fucoidan, a SR-A agonist, may contribute to macrophage apoptosis during ER stress by inhibiting autophagy.