Dysregulated activation of the CDK4/6 kinases is a hallmark of most mammary-derived carcinomas. ATP competitive inhibitors against this complex have been recently advanced in the clinic and shown significant activity, particularly against tumors driven by the estrogen receptor (ER). However, resistance to these compounds has begun to emerge often months to years after their initiation. We investigated potential mechanisms of resistance utilizing cell line models which are highly sensitive to this class of drugs. After prolonged exposure to the selective and potent CDK4/6 inhibitor LY2835219, clones emerged and several were found to harbor amplification of the CDK6 kinase. Amplification of CDK6 resulted in a marked increase in CDK6 expression and reduced response of the CDK4/6 target, pRb, to CDK4/6 inhibitors. Knockdown of CDK6 restored drug sensitivity while enforced overexpression of CDK6 was sufficient to mediate drug resistance. Not only did CDK6 overexpression mediate resistance to CDK4/6 inhibitors, it also led to reduced expression of the ER and progesterone receptor (PR), and diminished responsiveness to ER antagonism. The reduced ER/PR expression after CDK4/6 inhibitor resistance was additionally observed in tumor biopsy specimens from patients treated with these drugs. Alternative mechanisms of resistance to CDK4/6 inhibitors such as loss of pRb and Cyclin E1 overexpression also exhibited decreased hormone responsiveness suggesting that the clinical paradigm of sequential endocrine-based therapy may be ineffective in some settings of acquired CDK4/6 resistance.

The aim of the present study was to clarify the activation of ferroptosis in different breast cancer cells by sulfasalazine (SAS) and to explore the relationship between the estrogen receptor (ER) and the transferrin receptor (TFRC). MDA-MB-231 and T47D cells were treated with SAS for 24 h. Changes in cell morphology were observed under a microscope. CCK-8 was used to detect the proliferation inhibition rate and determine the IC 50 values. Western blotting was used to detect the expression of glutathione peroxidase 4 (GPX4) and xCT. Flow cytometry was used to identify changes in the production of reactive oxygen species (ROS). Mitochondrial morphological changes in T47D were observed using transmission electron microscopy. Changes in the mitochondrial membrane potential (MMP) were observed using confocal fluorescence microscopy. RT-PCR was used to detect the mRNA expression levels of TFRC and divalent metal transporter 1 (DMT1). Bioinformatics analysis was performed on TFRC expression in 1,208 breast cancer samples and its relationship with ER. TFRC expression was detected in various breast cancer tissues using immunohistochemistry and in various breast cancer cells using western blotting. Small interfering RNA (siRNA) knocked down ER expression in T47D cells, and changes in the TFRC mRNA and protein levels were observed. RT-PCR was used to detect TFRC expression in 87 clinical specimens. The results of the present study revealed that SAS could inhibit breast cancer cell viability, which was accompanied by an abnormal increase in ROS and a depletion of GPX4 and system x c-. Liproxstatin-1 reversed the SAS-induced increase in ROS. The cells treated with SAS had shrunken mitochondria and decreased MMP. SAS upregulated TFRC and DMT1. Knockdown of the ER increased TFRC expression in breast cancer cells. Immunohistochemistry indicated that TFRC expression was lower in ER + tissues than in ERtissues. After confirmation with RT-PCR in 87 clinical specimens, TFRC expression in ERtissue was revealed to be significantly higher than that of ER + tissue. In conclusion SAS could trigger ferroptosis in breast cancer cells, especially in cells with low ER expression. Therefore, SAS is a potential agent for breast cancer treatment.

Gut barrier dysfunction is triggered by gut microbiota dysbiosis that is closely associated with ulcerative colitis. Here, we first studied the prophylactic capacity of turmeric polysaccharides (TPS) to ameliorate dextran...

No abstract

Wormlike micelles constructed from a selenium-containing surfactant and a commercial diamine through a simple combination strategy can reversibly undergo a tandem reaction in response to CO and redox, exhibiting a transition between a gel-like fluid and a water-like fluid due to the evolution of aggregate structures from wormlike micelles to spherical micelles.

BackgroundLCL161, a novel Smac mimetic, is known to have anti-tumor activity and improve chemosensitivity in various cancers. However, the function and mechanisms of the combination of LCL161 and paclitaxel in non-small cell lung cancer (NSCLC) remain unknown.MethodsCellular inhibitor of apoptotic protein 1 and 2 (cIAP1&2) expression in NSCLC tissues and adjacent non-tumor tissues were assessed by immunohistochemistry. The correlations between cIAP1&2 expression and clinicopathological characteristics, prognosis were analyzed. Cell viability and apoptosis were measured by MTT assays and Flow cytometry. Western blot and co-immunoprecipitation assay were performed to measure the protein expression and interaction in NF-kB pathway. siRNA-mediated gene silencing and caspases activity assays were applied to demonstrate the role and mechanisms of cIAP1&2 and RIP1 in lung cancer cell apoptosis. Mouse xenograft NSCLC models were used in vivo to determine the therapeutic efficacy of LCL161 alone or in combination with paclitaxel.ResultsThe expression of cIAP1 and cIAP2 in Non-small cell lung cancer (NSCLC) tumors was significantly higher than that in adjacent normal tissues. cIAP1 was highly expressed in patients with late TNM stage NSCLC and a poor prognosis. Positivity for both cIAP1 and cIAP2 was an independent prognostic factor that indicated a poorer prognosis in NSCLC patients. LCL161, an IAP inhibitor, cooperated with paclitaxel to reduce cell viability and induce apoptosis in NSCLC cells. Molecular studies revealed that paclitaxel increased TNFα expression, thereby leading to the recruitment of various factors and the formation of the TRADD-TRAF2-RIP1-cIAP complex. LCL161 degraded cIAP1&2 and released RIP1 from the complex. Subsequently, RIP1 was stabilized and bound to caspase-8 and FADD, thereby forming the caspase-8/RIP1/FADD complex, which activated caspase-8, caspase-3 and ultimately lead to apoptosis. In nude mouse xenograft experiments, the combination of LCL161 and paclitaxel degraded cIAP1,2, activated caspase-3 and inhibited tumor growth with few toxic effects.ConclusionThus, LCL161 could be a useful agent for the treatment of NSCLC in combination with paclitaxel.

Metformin, the most widely administered oral anti-diabetic therapeutic agent, exerts its glucose-lowering effect predominantly via liver kinase B1 (LKB1)-dependent activation of adenosine monophosphate-activated protein kinase (AMPK). Accumulating evidence has demonstrated that metformin possesses potential antitumor effects. However, whether the antitumor effect of metformin is via the LKB1/AMPK signaling pathway remains to be determined. In the current study, the effects of metformin on proliferation, cell cycle progression, and apoptosis of human non-small cell lung cancer (NSCLC) H460 (LKB1-null) and H1299 (LKB1-positive) cells were assessed, and the role of LKB1/AMPK signaling in the anti-growth effects of metformin were investigated. Cell viability was determined using a 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay, cell cycle distribution and apoptosis were assessed by flow cytometry, and protein expression levels were measured by western blotting. Metformin inhibited proliferation, induced significant cell cycle arrest at the G0–G1 phase and increased apoptosis in NSCLC cells in a time- and concentration-dependent manner, regardless of the level of LKB1 protein expression. Furthermore, knockdown of LKB1 with short hairpin RNA (shRNA) did not affect the antiproliferative effect of metformin in the H1299 cells. Metformin stimulated AMPK phosphorylation and subsequently suppressed the phosphorylation of mammalian target of rapamycin and its downstream effector, 70-kDa ribosomal protein S6 kinase in the two cell lines. These effects were abrogated by silencing AMPK with small interfering RNA (siRNA). In addition, knockdown of AMPK with siRNA inhibited the effect of metformin on cell proliferation in the two cell lines. These results provide evidence that the growth inhibition of metformin in NSCLC cells is mediated by LKB1-independent activation of AMPK, indicating that metformin may be a potential therapeutic agent for the treatment of human NSCLC.

Chemokine (C-X-C motif) ligand 1 (CXCL1), a member of the CXC chemokine family, has been reported to be a critical factor in inflammatory diseases and tumor progression; however, its functions and molecular mechanisms in estrogen receptor α (ER)-negative breast cancer (BC) remain largely unknown. The present study demonstrated that CXCL1 was upregulated in ER-negative BC tissues and cell lines compared with ER-positive tissues and cell lines. Treatment with recombinant human CXCL1 protein promoted ER-negative BC cell migration and invasion in a dose-dependent manner, and stimulated the activation of phosphorylated (p)- extracellular signal-regulated kinase (ERK)1/2, but not p-STAT3 or p-AKT. Conversely, knockdown of CXCL1 in BC cells attenuated these effects. Additionally, CXCL1 increased the expression of matrix metalloproteinase (MMP)2/9 via the ERK1/2 pathway. Inhibition of MEK1/2 by its antagonist U0126 reversed the effects of CXCL1 on MMP2/9 expression. Furthermore, immunohistochemical analysis revealed a strong positive association between CXCL1 and p-ERK1/2 expression levels in BC tissues. In conclusion, the present study demonstrated that CXCL1 is highly expressed in ER-negative BC, and stimulates BC cell migration and invasion via the ERK/MMP2/9 pathway. Therefore, CXCL1 may serve as a potential therapeutic target in ER-negative BC.