Expression and function of heregulin-α and its receptors in the mouse mammary gland

Heregulin-α (HRGα) is a cytokine secreted by the mammary mesenchyme, adjacent to lobuloalveolar structures. To understand the role of HRGα and its receptors in mammary glands, and the underlying mechanisms, we performed this study to determine the expression and localization of HRGα and its receptors ErbB2 and ErbB3. We also determined the role of HRGα in the development of mammary glands, β-casein expression and secretion, Rab3A protein expression and the phosphorylation of HRGα signaling molecules using confocal laser scanning microscopy, tissue culture, capillary electrophoresis, Western blotting and enzyme-linked immunosorbent assays. We found that a peak was on pregnancy day 15. Changes of ErbB2 and ErbB3 expression were positively and linearly correlated with HRGα, indicating that HRGα positively regulates ErbB2 and ErbB3 expression. During pregnancy, HRGα enhanced the phosphorylation of STAT5, p42/p44, p38, PKC and Rab3A protein expression, stimulated the proliferation and differentiation of the ductal epithelial cells of mammary glands, and increased and maintained the expression and secretion of β-casein. During lactation, HRGα enhanced the phosphorylation of STAT5 and p38, inhibited the phosphorylation of PKC and Rab3A protein expression, maintained the morphology of the mammary glands and increased the secretion of lactoprotein to reduce the expression of β-casein in mammary epithelial cells. During involution, HRGα induced the phosphorylation of STAT3 and Rab3A protein expression, and inhibited the phosphorylation of PKC to stimulate the degeneration of mammary epithelial cells. It also inhibited the secretion of β-casein, resulting in increased levels of β-casein in mammary epithelial cells.     

6-Gingerol inhibits ROS and iNOS through the suppression of PKC-α and NF-κB pathways in lipopolysaccharide-stimulated mouse macrophages

Inflammation is involved in numerous diseases, including chronic inflammatory diseases and the development of cancer. Many plants possess a variety of biological activities, including antifungal, antibacterial and anti-inflammatory activities. However, our understanding of the anti-inflammatory effects of 6-gingerol is very limited. We used lipopolysaccharide (LPS)-stimulated macrophages as a model of inflammation to investigate the anti-inflammatory effects of 6-gingerol, which contains phenolic structure. We found that 6-gingerol exhibited an anti-inflammatory effect. 6-Gingerol could decrease inducible nitric oxide synthase and TNF-α expression through suppression of I-κBα phosphorylation, NF-κB nuclear activation and PKC-α translocation, which in turn inhibits Ca²⁺ mobilization and disruption of mitochondrial membrane potential in LPS-stimulated macrophages. Here, we demonstrate that 6-gingerol acts as an anti-inflammatory agent by blocking NF-κB and PKC signaling, and may be developed as a useful agent for the chemoprevention of cancer or inflammatory diseases.     

CPT2 down-regulation promotes tumor growth and metastasis through inducing ROS/NFκB pathway in ovarian cancer

BackgroundCarnitine palmitoyltransferase 2 (CPT2) is a rate-limiting enzyme involved in fatty acid β-oxidation (FAO) regulation. Recently, it has been increasingly recognized that lipid metabolism dysregulation is closely implicated in tumorigenesis. However, the involvement of CPT2 in the progression of cancer is still largely unclear, especially in ovarian cancer (OC).MethodsIn the present study, CPT2 expression and its clinical significance were determined in OC tissues and cells. The biological functions and molecular mechanisms of CPT2 in OC growth and metastasis were determined by in vitro and in vivo assays.FindingsWe found that CPT2 was frequently down-regulated in primary ovarian serous carcinomas, which is significantly correlated with poor survival of ovarian cancer patients. Functional experiments revealed that CPT2 inhibited OC cell growth and metastasis via suppression of G1/S cell cycle transition and epithelial to mesenchymal transition (EMT), as well as induction of cell apoptosis. Mechanistically, suppression of ROS/NFκB signaling pathway by increasing fatty acid oxidation-derived NADPH production was involved in the anti-tumorigenic functions of CPT2 in OC cells.InterpretationAltogether, our findings demonstrate that CPT2 functions as a potential tumor suppressor in OC progression. CPT2 may serve as a novel prognostic marker and therapeutic target in OC.     

Studies on the particulate lactose synthetase of mouse mammary gland and the role of α-lactalbumin in the initiation of lactose synthesis

1. Some of the kinetic properties of the particulate lactose synthetase of mouse mammary gland were investigated and shown to resemble those that have been reported for the soluble enzyme. Typical values for intact preparations were 2.3mum for the apparent K(m) for alpha-lactalbumin at 40mm-glucose and 1.7mm for the apparent K(m) for glucose at the endogenous concentration of alpha-lactalbumin. 2. Digitonin treatment increased total assayable activity approximately twofold but almost eliminated the endogenous activity found in the absence of alpha-lactalbumin, these findings being consistent with the location of endogenous activity within Golgi vesicles. 3. From the properties of the particulate fraction from lactating mice it was deduced that the effective endogenous alpha-lactalbumin concentrations were in the range 1-10mum. 4. The concentration of alpha-lactalbumin was not significantly different in particles isolated at various stages of pregnancy and early lactation. 5. The implications of these results for the control of lactose synthetase in vivo are discussed.     

Angiotensin II promotes differentiation of mouse embryonic stem cells to smooth muscle cells through PI3-kinase signaling pathway and NF-κB

Embryonic stem cells (ES cells), the pluripotent derivatives of the inner cell mass from blastocysts, have the capacity for unlimited growth, self-renewal and differentiation toward all types of somatic cells. Angiotensin II (Ang II), the most important effector peptide of the renin–angiotensin system, is also an angiogenesis factor. However, the potential impact of Ang II on ES cell differentiation is still unknown. In the present study, we have successfully induced the differentiation of ES cells into smooth muscle cells (SMCs) on collagen IV. Interestingly, incubation of ES cells with Ang II further promoted SMC differentiation from ES cells, which was abolished by prior treatment with Ang II type 1 (AT1) receptor antagonist losartan, but not Ang II type 2 (AT2) receptor antagonist PD123319. Moreover, we found that, in parallel with SMC specific-marker induction, the expression levels of phosphoAkt and NF-Kappa B (NF-κB) p50 were up-regulated by Ang II. Importantly, addition of phosphoinositide-3 kinase (PI3K) inhibitor LY294002 led to a marked inhibition of Ang II induced SMC specific markers, phosphoAkt and NF-κB p50 expression. Furthermore, NF-κB inhibitor BAY11-7082 can inhibit Ang II induced expression of SMC specific markers. Thus, we demonstrate for the first time that Ang II plays a promotive role in the stage of ES cell differentiation to SMCs through AT1 receptor. We further confirmed that PI3K/Akt signaling pathway and NF-κB play key roles in this process.     

Testes-specific protease 50 (TSP50) promotes cell proliferation through the activation of the nuclear factor κB (NF-κB) signalling pathway

TSP50 (testes-specific protease 50) is a testis-specific expression protein, which is expressed abnormally at high levels in breast cancer tissues. This makes it an attractive molecular marker and a potential target for diagnosis and therapy; however, the biological function of TSP50 is still unclear. In the present study, we show that overexpression of TSP50 in CHO (Chinese-hamster ovary) cells markedly increased cell proliferation and colony formation. Mechanistic studies have revealed that TSP50 can enhance the level of TNFα (tumour necrosis factor α)- and PMA-induced NF-κB (nuclear factor κB)-responsive reporter activity, IκB (inhibitor of NF-κB) α degradation and p65 nuclear translocation. In addition, the knockdown of endogenous TSP50 in MDA-MB-231 cells greatly inhibited NF-κB activity. Co-immunoprecipitation studies demonstrated an interaction of TSP50 with the NF-κB-IκBα complex, but not with the IKK (IκB kinase) α/β-IKKγ complex, which suggested that TSP50, as a novel type of protease, promoted the degradation of IκBα proteins by binding to the NF-κB-IκBα complex. Our results also revealed that TSP50 can enhance the expression of NF-κB target genes involved in cell proliferation. Furthermore, overexpression of a dominant-negative IκB mutant that is resistant to proteasome-mediated degradation significantly reversed TSP50-induced cell proliferation, colony formation and tumour formation in nude mice. Taken together, the results of the present study suggest that TSP50 promotes cell proliferation, at least partially, through activation of the NF-κB signalling pathway.     

NFκB mediated elevation of KCNJ11 promotes tumor progression of hepatocellular carcinoma through interaction of lactate dehydrogenase A

It has been well documented that changes in ion fluxes across cellular membranes is fundamental in maintaining cellular homeostasis. Dysregulation and/or malfunction of ion channels are critical events in the pathogenesis of diverse diseases, including cancers. In this study, we focused on the study of K⁺ channels in hepatocellular carcinoma (HCC). By data mining TCGA cohort, the expression of 27 K⁺ channels was investigated and KCNJ11 was identified as a key dysregulated K⁺ channels in HCC. KCNJ11 was differentially expressed in HCC and predicted a poor prognosis in HCC patients. Inhibition of NFκB signaling suppressed KCNJ11 expression in HCC cells. Knockdown of KCNJ11 expression inhibited cell proliferation, promoted cell apoptosis, and reduced cell invasive capacity. Mechanistically, we found that KCNJ11 promotes tumor progression through interaction with LDHA and enhancing its enzymatic activity. Pharmacological inhibition of LDHA largely compromised the oncogenic function of KCNJ11 in cell proliferation, cell apoptosis, and cell invasion. Collectively, our data, as a proof of principle, demonstrate that KCNJ11 acts as an oncogene in HCC though forming a complex with LDHA and suggest that targeting KCNJ11 can be developed as a candidate tool to dampen HCC.     

Physiological levels of Pik3ca(H1047R) mutation in the mouse mammary gland results in ductal hyperplasia and formation of ERα-positive tumors

PIK3CA, the gene coding for the p110α subunit of phosphoinositide 3-kinase, is frequently mutated in a variety of human tumors including breast cancers. To better understand the role of mutant PIK3CA in the initiation and/or progression of breast cancer, we have generated mice with a conditional knock-in of the common activating mutation, Pik3ca(H1047R), into one allele of the endogenous gene in the mammary gland. These mice developed a ductal anaplasia and hyperplasia by 6 weeks of age characterized by multi-layering of the epithelial lining of the mammary ducts and expansion of the luminal progenitor (Lin(-); CD29(lo); CD24(+); CD61(+)) cell population. The Pik3ca(H1047R) expressing mice eventually develop mammary tumors with 100% penetrance but with a long latency (>12 months). This is significantly longer than has been reported for transgenic models where expression of the mutant Pik3ca is driven by an exogenous promoter. Histological analysis of the tumors formed revealed predominantly ERα-positive fibroadenomas, carcinosarcomas and sarcomas. In vitro induction of Pik3ca(H1047R) in immortalized mammary epithelial cells also resulted in tumor formation when injected into the mammary fat pad of immunodeficient recipient mice. This novel model, which reproduces the scenario of a heterozygous somatic mutation occurring in the endogenous PIK3CA gene, will thus be a valuable tool for investigating the role of Pik3ca(H1047R) mutation in mammary tumorigenesis both in vivo and in vitro.     

Glucocorticoid-mediated anti-inflammatory effect through NFκB is preserved in the absence of Dexras1

Glucocorticoids effectively mediate the resolution of inflammation, but long-term use of glucocorticoids inevitably causes metabolic side effects. However, it is unknown if metabolic effectors such as Dexras1, a dexamethasone-stimulated protein, play a role in the anti-inflammatory outcome of dexamethasone. Here, we demonstrate that Dexras1 is required for the dexamethasone-induced upregulation of annexin A1 expression, but is not involved in the reduction of inflammation as evidenced by decreased pro-inflammatory parameters. In the absence of Dexras1, lipopolysaccharide (LPS)-induced interleukin-6 expression was suppressed when murine macrophage RAW264.7 cells were treated with dexamethasone. Similar observations were made in the blood of Dexras1 knockout mice. Furthermore, dexamethasone suppressed the LPS-stimulated increase of NFκB-p65 in both control and Dexras1-absent RAW264.7 cells. Interestingly, depletion of Dexras1 resulted in the loss of pERK production. These results suggest that Dexras1 is involved primarily in the metabolic side effects and its inhibition preserves the anti-inflammatory action of glucocorticoids. Thus, the inhibition of Dexras1 will be an excellent target for reducing steroid-induced side effects.     

The differential actions of cortisol on the accumulation of α-lactalbumin and casein in midpregnant mouse mammary gland in culture

The dose-response relationship between cortisol and the accumulation of the two milk proteins, casein and α-lactalbumin, was studied in organ culture of mammary gland from midpregnant mice. The accumulation of casein was low in culture with insulin but was enhanced by the further addition of prolactin. Further increases in casein were effected by the addition of cortisol in increasing concentrations up to 3 × 10^?6 M, which was optimal for the accumulation of this protein. The content of α-lactalbumin in explants was similarly low in culture with insulin alone, but, in contrast, was increased to a maximal level by the addition of insulin and prolactin. The addition of cortisol up to 3 × 10^?8 M with insulin and prolactin did not further increase the level of α-lactalbumin; in fact, at concentrations above 3 × 10^?7 M the steroid caused progressive inhibition of the accumulation of this protein in cultured explants. Studies of the appearance of casein and α-lactalbumin in incubation medium during organ culture revealed the presence of substantial amounts of these milk proteins. During the first 2 days of culture with insulin, prolactin and 3 × 10^?6 M cortisol, the amount of α-lactalbumin in culture medium was almost equal to the level found in tissue, whereas in the presence of 3 × 10^?8 M cortisol, or in the absence of exogenous steroid, over 70% of total α-lactalbumin was retained in tissue. The observed difference in the amount of α-lactalbumin in culture medium can, however, only partially account for the inhibitory effect of high doses of cortisol on the accumulation of α-lactalbumin in cultured mammary explants. In contrast to α-lactalbumin, the relative amount of casein in culture medium containing insulin and prolactin was smaller—19% of total casein synthesized—and was further reduced to 16% and 11% of the total in the presence of 3 × 10^?8 M and 3 × 10^?6 M cortisol, respectively. The above results indicate that cortisol exerts dose-dependent differential actions on the accumulation of casein and α-lactalbumin in mouse mammary epithelium in vitro.     

Doxorubicin-induced senescence through NF-κB affected by the age of mouse mesenchymal stem cells

The senescence is proposed as a defense mechanism against many anticancer drugs. This complication is marked by differences in cell appearance and inner structures underlying the impairment in function. In this experiment, doxorubicin-induced senescence was assessed in mesenchymal stem cells (MSCs) isolated from the bone marrow of different-aged Balb/c mice (1, 8, and 16 months old). In addition, doxorubicin kinetics in culture medium were investigated to compare the drug absorption rate by different-aged MSCs. Several methods were exerted including Sandwich ELISA for NF-κB activation, propidium iodide staining for cell cycle analysis, Flow-fluorescent in-situ hybridization (Flow-FISH) assay for telomere length measurement, and specific staining for evaluation of β-galactosidase. Determination of doxorubicin in a medium was performed by high-performance liquid chromatography technique. Following doxorubicin exposure, cells underwent substantial telomere shortening, cell cycle arresting in G2 phase, and increased β-galactosidase activity. Interestingly, the enhanced level of NF-κB was observed in all age groups. The highest and lowest sensitivity to telomere shortening attributed to 1- and 8-month-old MSCs, respectively. In consistent with Flow-FISH results, the β-galactosidase activity was higher in young-aged MSCs after treatment. Statistical analysis indicated a correlation between the reduction of telomere length and cessation in G2 phase. Regarding the obtained kinetics equations, the rate of doxorubicin absorption by all aged MSCs followed the same trend. In conclusion, the changing of some elements involved in doxorubicin-induced senescence can be affected by the age of the cells significantly in young MSCs than two other age groups. Hereupon, these changing patterns can open new insights to develop anticancer therapeutic strategies.     

Regulation of the mouse gene encoding TAFI by TNFα: role of NFκB binding site

Thrombin-activable fibrinolysis inhibitor (TAFI) is a plasma pro-carboxypeptidase, encoded by the gene CPB2, with roles in both inhibition of fibrinolysis and inflammation. In mice, plasma TAFI levels and hepatic CPB2 mRNA expression were found to increase within 24h after intra-peritoneal lipopolysaccharide (LPS) injection. On the other hand, plasma TAFI in humans decrease in experimental endotoxemia and sepsis and we have previously demonstrated that CPB2 mRNA abundance in human hepatoma cells is decreased by inflammatory cytokines. Here, we have evaluated the effects of TNFα on mouse CPB2 expression. Treatment of primary mouse hepatocytes or the mouse hepatic cell line FL83B with TNFα for 12-48h resulted in increases in CPB2 mRNA abundance of up to 2-fold; mouse TAFI protein levels secreted from FL83B cells increased 2.7-fold after 48h treatment with TNFα. When FL83B cells were transfected with reporter plasmids containing the mouse CPB2 5'-flanking region, treatment with TNFα for 24 and 48h resulted in a 1.5-fold increased mouse CPB2 promoter activity. Mutation of a putative NFκB site not conserved in the human gene ablated the increased promoter activity observed following TNFα treatment. This site binds NFκB as assessed by gel mobility shift assays, and TNFα treatment increases the translocation of NFκB from the cytoplasm to the nucleus of mouse hepatocytes. These results demonstrate that the unique NFκB site in the mouse CPB2 promoter is functional and mediates the upregulation of mouse CPB2 expression by TNFα via increase in NFκB translocation to the nucleus.     

Downregulated circRNA_CDKN1A promotes gallbladder cancer progression through activation of the NF-κB pathway

This study uncovered the potential clinical value and molecular driving mechanisms of circular RNAs (circRNAs) in gallbladder cancer (GBC). Differentially expressed circRNAs in GBC cells were screened by high-throughput sequencing. CircRNA_CDKN1A (circBase ID: hsa_circ_0076194) was knocked out in BGC-SD cells through transfection with sh-circRNA_CDKN1A. Then, proliferation was investigated via CCK8 and EdU assays, apoptosis via flow cytometry, migration via wound healing assays, and invasion via Transwell assays. Bioinformatics analysis of circRNA_CDKN1A-related signaling pathways was performed using MetScape and g:Profiler. Results showed that the knockdown of circRNA_CDKN1A enhanced the proliferation, migration, and invasion of GBC cells and inhibited apoptosis. In addition, knocking out circRNA_CDKN1A promoted GBC cell proliferation and enhanced the dry indices of the OCT4 protein and CD34 expression levels. The knockdown of circRNA_CDKN1A activated the epithelial–mesenchymal transition pathway. Bioinformatics analysis revealed that the biological role of circRNA_CDKN1A in GBC cells involved the NF-κB pathway. LY2409881, which is an NF-κB inhibitor, reversed the effects induced by the knockdown of circRNA_CDKN1A in GBC-SD cells. In summary, the knockdown of circRNA_CDKN1A promoted the progression of GBC by activating the NF-κB signaling pathway. For the first time, this study revealed the mechanism of circRNA_CDKN1A-mediated regulatory action in GBC and identified the newly discovered circRNA_CDKN1A–NF-κB signaling axis as a potentially important candidate for clinical therapy and prognostic diagnosis of GBC.