17-375 Sigma-AldrichEZ-Zyme™ Chromatin Prep Kit

In this study, we present a medium throughput siRNA screen platform to identify inflammation genes that regulate cancer cell stemness. We identified several novel candidates that decrease OCT4 expression and reduce the ALDH + subpopulation both of which are characteristic of stemness. Furthermore, one of the novel candidates ICAM3 up-regulates in the ALDH + subpopulation, the side population and the developed spheres. ICAM3 knockdown reduces the side population, sphere formation and chemo-resistance in MDA-MB-231 human breast cancer cells and A549 lung cancer cells. In addition, mice bearing MDA-MB-231-shICAM3 cells develop smaller tumors and fewer lung metastases versus control. Interestingly, ICAM3 recruits and binds to Src by the YLPL motif in its intracellular domain which further activates the PI3K-AKT phosphorylation cascades. The activated p-AKT enhances SOX2 and OCT4 activity and thereby maintains cancer cell stemness. Meanwhile, the p-AKT facilitated p50 nuclear translocation/activation enhances p50 feedback and thereby promotes ICAM3 expression by binding to the ICAM3 promoter region. On this basis, Src and PI3K inhibitors suppress ICAM3-mediated signaling pathways and reduce chemo-resistance which results in tumor growth suppression in vitro and in vivo. In summary, we identify a potential CSC regulator and suggest a novel mechanism by which ICAM3 governs cancer cell stemness and inflammation.

It is well established that hypoxia induces epithelial‑mesenchymal transition in vitro and in vivo. However, the role of hypoxia in endothelial‑mesenchymal transition (EndMT), an important process in the pathogenesis of pulmonary hypertension, is not well‑characterized. The present study demonstrated a significant downregulation of the endothelial marker CD31 and its co‑localization with a mesenchymal marker, α‑smooth muscle actin (α‑SMA), in the intimal layer of small pulmonary arteries of rats exposed to chronic hypoxia. These results suggest a possible role of hypoxia in inducing EndMT in vivo. Consistent with these observations, pulmonary microvascular endothelial cells (PMVECs) cultured under hypoxic conditions exhibited a significant decrease in CD31 expression, alongside a marked increase in the expression of α‑SMA and two other mesenchymal markers, collagen (Col) 1A1 and Col3A1. In addition, hypoxia promoted the proliferation and migration of α‑SMA‑expressing mesenchymal‑like cells, but not of PMVECs. Of note, knockdown of hypoxia‑inducible factor 1α (HIF‑1α) effectively inhibited hypoxic induction of α‑SMA, Col1A1 and the transcription factor Twist1, while rescuing hypoxic suppression of CD31; these results suggest that HIF‑1α is essential for hypoxia‑induced EndMT and that it serves as an upstream regulator of Twist1. Mechanistically, HIF‑1α was identified to bind to the promoter of the Twist1 gene, thus activating Twist1 transcription and regulating EndMT. Collectively, the present results indicate that the HIF‑1α/Twist1 pathway has a critical role in mediating the effect of hypoxia‑induced EndMT in pulmonary arterial remodeling.

Prefoldin (PFDN) is a co-chaperone protein that is primarily known for its classic cytoplasmic functions in the folding of actin and tubulin monomers during cytoskeletal assembly. Here, we report a marked increase in prefoldin subunit 1 (PFDN1) levels during the transforming growth factor (TGF)-β1-mediated epithelial-mesenchymal transition (EMT) and in human lung tumor tissues. Interestingly, the nuclear localization of PFDN1 was also detected. These observations suggest that PFDN1 may be essential for important novel functions. Overexpression of PFDN1 induced EMT and cell invasion. In sharp contrast, knockdown of PFDN1 generated the opposite effects. Overexpression of PFDN1 was also found to induce lung tumor growth and metastasis. Further experiments showed that PFDN1 overexpression inhibits the expression of cyclin A. PFDN1 suppressed cyclin A expression by directly interacting with the cyclin A promoter at the transcriptional start site. Strikingly, cyclin A overexpression abolished the above PFDN1-mediated effects on the behavior of lung cancer cells, whereas cyclin A knockdown alone induced EMT and increased cell migration and invasion ability. This study reveals that the TGF-β1/PFDN1/cyclin A axis is essential for EMT induction and metastasis of lung cancer cells.

Regulatory factor X-5 (RFX5) was previously characterized as an essential and highly specific regulator of major histocompatibility class II (MHCII) gene expression in the immune system. We found that RFX5 is significantly upregulated in hepatocellular carcinoma (HCC) tumors and cell lines compared with non-tumor tissues in mRNA expression levels, but it fails to induce the expression of MHCII. However, RFX5 can strongly bind to the tripeptidyl peptidase 1 (TPP1) promoter region and then increase its transcriptional activity. We also found that manipulation the expression of RFX5 can significantly affect the expression of TPP1 in HepG2, which suggested that RFX5 can transcriptionally activate TPP1 in HCC. Moreover, TPP1 is overexpressed in HCC tissues and significantly correlated with poor prognosis of HCC patients, suggesting that it may have potential biological implications in HCC.

Identification of aberrant histone H3 phosphorylation during chemical carcinogenesis will lead to a better understanding of the substantial roles of histone modifications in cancer development. To explore whether aberrant H3 phosphorylation contributes to chemical carcinogenesis, we examined the dynamic changes of H3 phosphorylation at various residues in chemical carcinogen-induced transformed human cells and human cancers. We found that histone H3 phosphorylation at Ser10 (p-H3S10) and Ser28 (p-H3S28) was upregulated by 1.5-4.8 folds and 2.1-4.3 folds, respectively in aflatoxin B1 -transformed hepatocytes L02 cells (L02RT-AFB1 ), benzo(a)pyrene-transformed HBE cells (HBERT-BaP), and coke oven emissions-transformed HBE cells (HBERT-COE). The ectopic expression of histone H3 mutant (H3S10A or H3S28A) in L02 cells led to the suppression of an anchorage-independent cell growth as well as tumor formation in immunodeficient mice. In addition, an enhanced p-H3S10 was found in 70.6% (24/34) of hepatocellular carcinoma (HCC), and 70.0% (21/30) of primary lung cancer, respectively. Notably, we found that expression of H3 carrying a mutant H3S10A or H3S28A conferred to cells the ability to maintain a denser chromatin and resistance to induction of DNA damage and carcinogen-induced cell transformation. Particularly, we showed that introduction of a mutant H3S10A abolished the bindings of p-H3S10 to the promoter of DNA repair genes, PARP1 and MLH1 upon AFB1 treatment. Furthermore, we revealed that PP2A was responsible for dephosphorylation of p-H3S10. Taken together, these results reveal a key role of persistent H3S10 or H3S28 phosphorylation in chemical carcinogenesis through regulating gene transcription of DNA damage response (DDR) genes.

Parathyroid Hormone-Like Hormone (PTHLH) is an autocrine/paracrine ligand that is up-regulated in head and neck squamous cell carcinoma (HNSCC). However, the cellular function and regulatory mechanism in HNSCC remains obscure. We investigated the clinical significance of PTHLH in HNSCC patients, and verified the role of RUNX2/PTHLH axis, which is stimulated HNSCC cell growth. In patients, PTHLH is a poor prognosis marker. PTHLH expression lead to increasing the cell proliferation potential through an autocrine/paracrine role and elevating blood calcium level in Nod-SCID mice. In public HNSCC microarray cohorts, PTHLH is found to be co-expressed with RUNX2. Physiologically, PTHLH is regulated by RUNX2 and also acting as key calcium regulator. However, elevations of calcium concentration also increased the RUNX2 expression. PTHLH, calcium, and RUNX2 form a positive feedback loop in HNSCC. Furthermore, ectopic RUNX2 expression also increased PTHLH expression and promoted proliferation potential through PTHLH expression. Using cDNA microarray analysis, we found PTHLH also stimulated expression of cell cycle regulators, namely CCNA2, CCNE2, and CDC25A in HNSCC cells, and these genes are also up-regulated in HNSCC patients. In summary, our results reveal that PTHLH expression is a poor prognosis marker in HNSCC patients, and RUNX2-PTHLH axis contributes to HNSCC tumor growth.

IL-12 and IL-23 are important host defense factors produced by APCs against certain intracellular and extracellular pathogens. Their dysregulation has also been implicated in several autoimmune diseases. The nucleotide polymorphism in the promoter region of Il12b (rs41292470 consisting of the long or short allele) encoding the shared subunit of IL-12 and IL-23, p40, has been reported to associate with susceptibility to infectious diseases and autoimmune disorders. How these genetic variants impact Il12b expression at the molecular level was unclear. We established an Il12b promoter-luciferase reporter system containing the long or short allele driving the reporter gene expression and found that the long allele (infection-resistant) displayed ∼2-fold higher transcriptional activity than the short allele (infection-susceptible), associated with a selective and differential nuclear binding activity to the two alleles in activated macrophages. DNA pull-down assays coupled with mass spectrometry analyses identified the specific DNA binding activity as poly(ADP-ribose) polymerase 1 (PARP-1). Small hairpin RNA-mediated knockdown of the endogenous PARP-1 expression resulted in reduced p40 mRNA expression and Il12b promoter activity. Bone marrow-derived macrophages from PARP-1-deficient mice had decreased p40 expression at both mRNA and protein levels. Furthermore, selective PARP-1 inhibitors resulted in impaired production of IL-12p40 and IL-23 in bone-marrow derived macrophages and PBMCs. Chromatin immunoprecipitation assay revealed that PARP-1 could bind specifically to Il12b in LPS-stimulated macrophages. Our study opens the way for further elucidating the molecular mechanism whereby allele-specific immune responses to foreign and self-antigens mediated by IL-12/IL-23 are controlled in an individually variable manner.

Precise coordination of cell growth, proliferation and differentiation is essential for the development of multicellular organisms. Here, we report that although the mechanistic target of rapamycin complex 1 (mTORC1) activity is required for chondrocyte growth and proliferation, its inactivation is essential for chondrocyte differentiation. Hyperactivation of mTORC1 via TSC1 gene deletion in chondrocytes causes uncoupling of the normal proliferation and differentiation programme within the growth plate, resulting in uncontrolled cell proliferation, and blockage of differentiation and chondrodysplasia in mice. Rapamycin promotes chondrocyte differentiation and restores these defects in mutant mice. Mechanistically, mTORC1 downstream kinase S6K1 interacts with and phosphorylates Gli2, and releases Gli2 from SuFu binding, resulting in nuclear translocation of Gli2 and transcription of parathyroid hormone-related peptide (PTHrP), a key regulator of bone development. Our findings demonstrate that dynamically controlled mTORC1 activity is crucial to coordinate chondrocyte proliferation and differentiation partially through regulating Gli2/PTHrP during endochondral bone development.

RelA, the most important regulator of NF-kB activity, and its mechanisms in keratoplasty immune rejection have not been fully investigated. In the present study, lentivirus-mediated silencing of RelA expression in a bone marrow-derived dendritic cell (BMDC) model was tested. The BMDCs were transfected with RelA-shRNA to induce an immature, maturation-resistant and tolerogenic phenotype, while not significantly changing IFN-γ, IL-10 and IL-17 expression. A fully allogeneic rat cornea transplant model was established for in vivo studies. The allograft mean survival time (MST) of lv-shRelA-DC injection groups were significantly longer than the untreated BMDC group and control group. The corneal opacity and neovascularization scale of the lv-shRelA-DC injection groups were slight compared to pair control others. Postoperative flow cytometric analysis revealed that the percentage of Treg positive cells was dramatically increased in animals that received an lv-shRelA-DC injection. ELISA and qRT-PCR analyses of serum showed that IFN-γ and IL-17 expression were suppressed by lv-shRelA-DC treatement. In vivo experiments demonstrated that IL-10 induced immunosuppression was partly attributed to injection of lv-shRelA-DC throughout the experiment, differing from the general anti-inflammatory factors. Luciferase and Chromatin IP evaluation showed that RelA knockdown in BMDCs significantly reduces DNA binding to IFN-γ, IL-10 and the IL-17 promoter and inhibited of transcriptional activity. Taken together, this study illustrates a significant role of RelA in mediating the corneal neovascularization by affecting IL-17 expression. Our comprehensive analysis shows that the significant role of RelA provides a novel and feasible therapeutic approach for the prevention of corneal allograft rejection.

It has been shown that HPV16 E7, but not other genotypes, can bind to scaffold protein CUL2 during inducing cervical carcinogenesis, but the expression level, associated regulating mechanism, and potential carcinogenicity of CUL2 itself is still unknown as yet. Here, we demonstrated that CUL2 was specifically overexpressed in HPV16 positive cervical cancer cells and tissues, and CUL2 expression was significantly increased along with the cervical lesion progression and positively correlated with HPV16 E7. CUL2 knockdown slowed the growth of xenograft tumors in mouse models. Importantly, CUL2 specifically bound to HPV16 E7, but not HPV18 E7. Moreover, CUL2 acted as a direct target of miR-424, and reversely suppressed miR-424; E2F transcription factor 1 (E2F1) suppressed miR-424 expression; CUL2 bound to E2F1 and promoted E2F1 expression. Our results indicate the existence of a regulatory loop among CUL2, E2F1, and miR-424 in HPV16 positive cervical cancer cells. Our results suggest that E7 recruited CUL2, driven by CUL2/E2F1/miR-424 regulatory loop, is overexpressed and accelerates HPV16-induced cervical carcinogenesis. Our findings may serve as one of the explanations for a clinical phenomenon that HPV16 possesses the strongest cervical carcinogenicity among high-risk HPV genotypes.