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Overexpression of nuclear coactivator steroid receptor coactivator 1 (SRC-1) and aberrant activation of the Hedgehog (Hh) signaling pathway are associated with various tumorigenesis; however, the significance of SRC-1 in colorectal cancer (CRC) and its contribution to the activation of Hh signaling are unclear. Here, we identified a conserved Hh signaling signature positively correlated with SRC-1 expression in CRC based on TCGA database; SRC-1 deficiency significantly inhibited the proliferation, survival, migration, invasion, and tumorigenesis of both human and mouse CRC cells, and SRC-1 knockout significantly suppressed azoxymethane/dextran sodium sulfate (AOM/DSS)-induced CRC in mice. Mechanistically, SRC-1 promoted the expression of GLI family zinc finger 2 (GLI2), a major downstream transcription factor of Hh pathway, and cooperated with GLI2 to enhance multiple Hh-regulated oncogene expression, including Cyclin D1, Bcl-2, and Slug. Pharmacological blockages of SRC-1 and Hh signaling retarded CRC progression in human CRC cell xenograft mouse model. Together, our studies uncover an SRC-1/GLI2-regulated Hh signaling looping axis that promotes CRC tumorigenesis, offering an attractive strategy for CRC treatment.

Programmed death-ligand 1 (PD-L1) is an important immunosuppressive molecule highly expressed on the surface of cancer cells. IFNγ triggered cancer cell immunosuppression against CD8

Backgroud: SRC-1 works as a transcriptional coactivator for steroid receptors and other transcrip-tional factors. SRC-1 is shown to play oncogenic roles in many cancers, like breast cancer and prostate cancer. Our lab anteriorly accounted that SRC-1 is highly expressed in human HCC spec-imens. SRC-1 accelerates HCC progression via enhancing Wnt/beta-catenin signaling. However, the role of SRC-1 in HCC metastasis is unknown. Methods: RNA inteference was used to knockdown the expression of SRC-1, and the protein level was detected via Western blot assay. Matrigel invasion assay was performed for assessment of HCC cell metastasis. MMP9 expression was detected via Zymography. Luciferase assays were performed to detect MMP-9 promoter activity. Results: In this study, we report that SRC-1 promotes HCC metastasis through enhancing MMP-9 expression. Knockdown of SRC-1 decreased HCC cell metastasis in vitro and in vivo by inhibiting the expression of MMP-9. SRC-1 mRNA level is found to positively correlated with MMP-9 mRNA level in a limited number cohort of HCC specimens and a larger number cohort of HCC specimen from GEO database. SRC-1 functions as a coactiva-tor for NF-κB and AP-1 to regulate MMP-9 promoter activity in HCC cells. Higher SRC-1 and MMP-9 expression correlates with a worse overall survival in HCC patients. Bufalin treatment, which can inhibit SRC-1 expression, can significantly decreased MMP-9 expression and inhibit HCC metastasis both in vitro and in vivo. Conclusion: Our results demonstrated that SRC-1 is a crucial modulator for HCC metastasis and offered a potential target for HCC therapy.

Inflammation theory has suggested that the pathogenesis of postoperative ileus (POI) involves the steroid receptor coactivator-3 (SRC-3). Therefore, we investigated the role of SRC-3 in the muscles of the small intestine using a mouse POI model. Here, we reported that intestinal manipulation (IM) significantly reduced the extent of phenol red migration in the entire gastrointestinal tract, and the calculated geometric center (GC) value in wild-type (WT) mice at 24 h after surgery was higher than that in the knockout (KO) mice and in the sham-operated control group. The expression of SRC-3 was upregulated in the mouse intestinal muscularis at 24 h after surgical manipulation, and the mRNA and protein levels of inflammatory cytokines were upregulated compared with those in the control group. At 24 h after IM, the number of neutrophils in the experimental group was significantly higher than that in the control group; in the IM group, the number of neutrophils in the SRC-3-/- mice was markedly higher than that in the WT mice. At 24 h after IM, the myeloperoxidase (MPO) activity in the experimental group was significantly higher than that in the control group. In the IM group, the MPO activity of the SRC-3-/- mice was markedly higher than that of the WT mice. In summary, proinflammatory cytokines, the number of neutrophils, and the MPO activity were significantly increased in the muscularis of the jejunum and ileum of KO mice after IM compared with those of the WT mice, indicating that SRC-3 might play a protective role in POI.

Posttranslational modifications (PTMs) of histones are well-established contributors in a variety of biological functions, especially tumorigenesis. Histone demethylase JMJD2D (also known as KDM4D), a member of the JMJD2 subfamily, promotes gene transcription by antagonizing H3K9 methylation. JMJD2D is an epigenetic factor coordinating androgen receptor activation, DNA damage repair, DNA replication, and cell cycle regulation. Recently, the oncogenic role of JMJD2D in colorectal cancer (CRC) and hepatocellular cancer (HCC) has been recognized. JMJD2D serves as a coactivator of β-catenin, Gli1/2, HIF1α, STAT3, IRF1, TCF4, and NICD or an antagonist of p53 to promote the progression of CRC and HCC. In this review, we summarize the molecular mechanisms of JMJD2D in promoting the progression of CRC and HCC as well as the constructive role of its targeting inhibitors in suppressing tumorigenesis and synergistically enhancing the efficacy of anti-PD-1/PD-L1 immunotherapy.

Histone demethylase JMJD2D can promote gene expression by specifically demethylating H3K9me2/3. The role of JMJD2D in colitis and colitis-associated colorectal cancer (CRC) progression remains unclear. Here, we show that colonic JMJD2D is induced by TNFα during dextran sulfate sodium-induced colitis. JMJD2D-deficient mice exhibit more severe colon damage and defective colon regeneration due to impaired Hedgehog signaling activation after colitis. JMJD2D knockdown in CRC cells suppresses Hedgehog signaling, resulting in reduced CRC growth and metastasis. Mechanistically, JMJD2D promotes Hedgehog target gene expression through interacting with Gli2 to reduce H3K9me3 levels at the promoter. Clinically, JMJD2D expression is upregulated and positively correlated with Gli2 expression in human inflammatory bowel disease specimens and CRC specimens. The JMJD2D inhibitor 5-c-8HQ or aspirin synergizes with Hedgehog inhibitor vismodegib to inhibit CRC cell proliferation and tumorigenesis. Collectively, our findings unveil an essential role of JMJD2D in activating the processes of colonic protection, regeneration, and tumorigenesis.

Background: As a histone demethylase, JMJD2D can enhance gene expression by specifically demethylating H3K9me2/3 and plays an important role in promoting colorectal cancer progression. However, its role in liver cancer remains unclear. Methods: The expression of JMJD2D was examined in human liver cancer specimens and non-tumorous liver tissues by immunohistochemical or immunoblot analysis. JMJD2D expression was knocked down in liver cancer cells using small hairpin RNAs, and cells were analyzed with Western blot, real-time PCR, cell viability, colony formation, and flow cytometry assays. Cells were also grown as tumor xenografts in nude mice, and the tumor cell proliferation and apoptosis were measured by immunohistochemical analysis. The relationship between JMJD2D and p53 was studied by co-immunoprecipitation, chromatin immunoprecipitation, and electric mobility shift assay. Wild-type and JMJD2D-knockout mice were intraperitoneally injected with diethylnitrosamine (DEN) to induce liver tumors and the liver cancer initiation and progression were investigated. Results: JMJD2D was frequently upregulated in human liver cancer specimens compared with non-tumorous liver tissues. The overall survival of liver cancer patients with high JMJD2D expression was significantly decreased compared to that with low JMJD2D expression. JMJD2D knockdown reduced liver cancer cell proliferation and xenograft tumor growth, sensitized cells to chemotherapeutic drug-induced apoptosis, and increased the expression of cell cycle inhibitor p21 and pro-apoptosis gene PUMA. Genetically, JMJD2D deficiency protected mice against DEN-induced liver cancer initiation and progression. Knockout of tumor suppressor p53 significantly reduced the effects of JMJD2D knockdown on cell proliferation, apoptosis, and the expression of p21 and PUMA, suggesting that JMJD2D regulates liver cancer cell functions in part through inhibiting p53 signaling pathway. Mechanistically, JMJD2D directly interacted with p53 and inhibited p53 recruitment to the p21 and PUMA promoters in a demethylation activity-independent manner, implicating a demethylase-independent function of JMJD2D as a novel p53 antagonist. In addition, JMJD2D could activate Wnt/β-catenin signaling to promote liver cancer cell proliferation. Conclusion: Our study demonstrates that JMJD2D can antagonize the tumor suppressor p53 and activate an oncogenic signaling pathway (such as Wnt/β-catenin signaling pathway) simultaneously to promote liver cancer initiation and progression, suggesting that JMJD2D may serve as a novel target for liver cancer treatment.

Pien Tze Huang (PZH) is a valuable traditional Chinese medicine, which has a variety of biological activities such as clearing heat-toxin, resolving blood stasis, detoxifying, relieving pain, and anti-inflammation. PZH has a partial role in suppressing the progression of CRC, while the underlying mechanism is a pending mystery; especially whether PZH mediates the immune escape of CRC remains unclear. Our study reported that PZH suppressed the proliferative activity of CRC by inhibiting Wnt/β-catenin signaling to down-regulate the expression of PCNA and Cyclin D1. In addition, PZH suppressed the immune escape of CRC and elevated the infiltration of CD8+ T cells in tumor tissues, which depends on the suppression of PD-L1 levels via inhibiting IFNGR1-JAK1-STAT3-IRF1 signaling. More importantly, PZH pharmacologically elevated the antitumor efficacy of anti-PD-1/PD-L1 immunotherapy as demonstrated by slower tumor growth, higher infiltration and function of CD8+ T cells in the combination of PZH and PD-1/PD-L1 antibody compared with monotherapy with either agent. These results demonstrate that PZH has the potential role in inhibiting CRC proliferation and immune evasion, especially the synergistic enhancement effect of PZH on immunotherapy.

Background & Aims Wnt signaling contributes to the development of colorectal cancer (CRC). We studied interactions between lysine demethylase 4D (KDM4D or JMJD2D) and β-catenin, a mediator of Wnt signaling, in CRC cell lines and the effects on tumor formation in mice. Methods We obtained colorectal tumor specimens and surrounding nontumor colon tissues (controls) from patients undergoing surgery in China; levels of JMJD2D were measured by immunohistochemical or immunoblot analysis. JMJD2D expression was knocked down in CRC (CT26, HCT116, and SW480 cells) using small hairpin RNAs, and cells were analyzed with viability, flow cytometry, colony formation, and transwell migration and invasion assays. Cells were also grown as tumor xenografts in nude mice or injected into tail veins or spleens of mice, and metastases were measured. We performed promoter activity, co-immunoprecipitation, and chromatin immunoprecipitation assays. We also performed studies with Apcmin/+ and JMJD2D-knockout mice; these mice were crossed, and colorectal tumor formation in offspring (Apcmin/+Jmjd2d+/+ and Apcmin/+Jmjd2d–/–) was analyzed. JMJD2D-knockout and wild-type (control) mice were given azoxymethane followed by dextran sodium sulfate to induce colitis-associated CRC; some mice were given the JMJD2D inhibitor 5-chloro-8-hydroxyquinoline (5-c-8HQ) or vehicle to examine the effects of 5-c-8HQ on intestinal tumor formation. Results Levels of JMJD2D were significantly higher in human colorectal tumors than in control tissues and correlated with levels of proliferating cell nuclear antigen. JMJD2D knockdown reduced CRC cell proliferation, migration, and invasion, as well as growth of xenograft tumors and formation of metastases in mice. JMJD2D was required for expression of β-catenin in CRC cell lines; ectopic expression of JMJD2D increased the promoter activities of genes regulated by β-catenin (MYC, CCND1, MMP2, and MMP9). We found that JMJD2D and β-catenin interacted physically and that JMJD2D demethylated H3K9me3 at promoters of β-catenin target genes. JMJD2D-knockout mice developed fewer colitis-associated colorectal tumors than control mice, and their tumor tissues had lower levels of β-catenin, MYC, cyclin D1, and proliferating cell nuclear antigen than tumors from control mice. Apcmin/+Jmjd2d–/– mice developed fewer and smaller colon tumors than Apcmin/+ mice. Mice given 5-c-8HQ developed smaller and fewer colitis-associated tumors, with lower levels of cell proliferation, than mice given vehicle. Apcmin/+ mice given 5-c-8HQ also developed fewer tumors in intestines and colons than mice given vehicle. Conclusions Levels of the histone demethylase JMJD2D are increased in human colorectal tumors compared with nontumor colon tissues. JMJD2D interacts with β-catenin to activate transcription of its target genes and promote CRC cell proliferation, migration, and invasion, as well as formation of colorectal tumors in mice.

Inflammation theory has suggested that the pathogenesis of postoperative ileus (POI) involves the steroid receptor coactivator-3 (SRC-3). Therefore, we investigated the role of SRC-3 in the muscles of the small intestine using a mouse POI model. Here, we reported that intestinal manipulation (IM) significantly reduced the extent of phenol red migration in the entire gastrointestinal tract, and the calculated geometric center (GC) value in wild-type (WT) mice at 24 h after surgery was higher than that in the knockout (KO) mice and in the sham-operated control group. The expression of SRC-3 was upregulated in the mouse intestinal muscularis at 24 h after surgical manipulation, and the mRNA and protein levels of inflammatory cytokines were upregulated compared with those in the control group. At 24 h after IM, the number of neutrophils in the experimental group was significantly higher than that in the control group; in the IM group, the number of neutrophils in the SRC-3

Cancer stem-like cells (CSCs) contribute to the high rate of tumor heterogeneity, metastasis, therapeutic resistance, and recurrence. Histone lysine demethylase 4D (KDM4D or JMJD2D) is highly expressed in colon and liver tumors, where it promotes cancer progression; however, the role of JMJD2D in CSCs remains unclear. Here, we show that JMJD2D expression was increased in liver cancer stem-like cells (LCSCs); downregulation of JMJD2D inhibited the self-renewal of LCSCs in vitro and in vivo and inhibited the lung metastasis of LCSCs by reducing the survival and the early lung seeding of circulating LCSCs. Mechanistically, JMJD2D promoted LCSC self-renewal by enhancing the expression of CSC markers EpCAM and Sox9; JMJD2D reduced H3K9me3 levels on the promoters of EpCAM and Sox9 to enhance their transcription via interaction with β-catenin/TCF4 and Notch1 intracellular domain, respectively. Restoration of EpCAM and Sox9 expression in JMJD2D-knockdown liver cancer cells rescued the self-renewal of LCSCs. Pharmacological inhibition of JMJD2D using 5-c-8HQ reduced the self-renewal of LCSCs and liver cancer progression. Collectively, our findings suggest that JMJD2D promotes LCSC self-renewal by enhancing EpCAM and Sox9 expression via Wnt/β-catenin and Notch signaling pathways and is a potential therapeutic target for liver cancer.

Hypoxia-inducible factor 1 (HIF1) signaling pathway plays a key role in cancer progression by enhancing glycolysis through activating the transcription of glycolytic genes. JMJD2D, a histone demethylase that specifically demethylates H3K9me2/3, can promote colorectal cancer (CRC) progression. However, it is unknown whether JMJD2D could promote CRC progression by enhancing glycolysis through activating HIF1 signaling pathway. In this study, we found that downregulation of JMJD2D inhibited the glycolysis in CRC cells through suppressing HIF1 signaling pathway to downregulate glycolytic gene expression. Restoring HIF1 signaling by enforced expression of HIF1α in JMJD2D-knockdown CRC cells partially recovered CRC cell glycolysis, proliferation, migration, invasion, xenograft growth, and metastasis, suggesting that JMJD2D promotes CRC progression by enhancing glycolysis through activating HIF1 signaling pathway. JMJD2D activated HIF1 signaling pathway through three different mechanisms: JMJD2D cooperated with the transcription factor SOX9 to enhance mTOR expression and then to promote HIF1α translation; JMJD2D cooperated with the transcription factor c-Fos to enhance HIF1β transcription; JMJD2D interacted and cooperated with HIF1α to enhance the expression of glycolytic gene. The demethylase-defective mutant of JMJD2D could not induce the expression of mTOR, HIF1α, HIF1β, and glycolytic genes, suggesting that the demethylase activity of JMJD2D is important for glycolysis through activating HIF1 signaling. Clinically, a highly positive correlation between the expression of JMJD2D and mTOR, HIF1β, and several glycolytic genes in human CRC specimens was identified. Collectively, our study reveals an important role of JMJD2D in CRC progression by enhancing glycolysis through activating HIF1 signaling pathway.

Steroid receptor coactivator 3 (SRC-3) is a transcriptional coactivator that interacts with nuclear receptors such as the estrogen receptor and the androgen receptor and several other transcription factors to enhance their effects on target gene expression. SRC-3 plays important roles in many developmental, physiological, and pathologic events, including body growth, mammary gland development, energy homeostasis, inflammatory regulation, and cancer initiation and progression. SRC-3 has been suggested to be involved in host defense against bacterial pathogens. In this review, we summarize the roles of SRC-3 in host defense against peritoneal and enteric bacterial infection and discuss the potential clinical implications.

Store-operated calcium entry (SOCE) is the predominant calcium entry mechanism in most cancer cells. SOCE is mediated by the endoplasmic reticulum calcium sensor STIMs (STIM1 and 2) and plasma membrane channel forming unit Orais (Orai 1-3). In recent years there is increasing evidence indicating that SOCE in cancer cells is dysregulated to promote cancer cell migration, invasion and metastasis. The overexpression of STIM and Orai proteins has been reported to correlate with the metastatic progression of various cancers. The hyperactive SOCE may promote metastatic dissemination and colonization by reorganizing the actin cytoskeleton, degrading the extracellular matrix and remodeling the tumor microenvironment. Here we discuss how these recent progresses provide novel insights to our understanding of tumor metastasis.

Hypoxia-inducible factor 1 (HIF1) signaling pathway plays a key role in cancer progression by enhancing glycolysis through activating the transcription of glycolytic genes. JMJD2D, a histone demethylase that specifically demethylates H3K9me2/3, can promote colorectal cancer (CRC) progression. However, it is unknown whether JMJD2D could promote CRC progression by enhancing glycolysis through activating HIF1 signaling pathway. In this study, we found that downregulation of JMJD2D inhibited the glycolysis in CRC cells through suppressing HIF1 signaling pathway to downregulate glycolytic gene expression. Restoring HIF1 signaling by enforced expression of HIF1α in JMJD2D-knockdown CRC cells partially recovered CRC cell glycolysis, proliferation, migration, invasion, xenograft growth, and metastasis, suggesting that JMJD2D promotes CRC progression by enhancing glycolysis through activating HIF1 signaling pathway. JMJD2D activated HIF1 signaling pathway through three different mechanisms: JMJD2D cooperated with the transcription factor SOX9 to enhance mTOR expression and then to promote HIF1α translation; JMJD2D cooperated with the transcription factor c-Fos to enhance HIF1β transcription; JMJD2D interacted and cooperated with HIF1α to enhance the expression of glycolytic gene. The demethylase-defective mutant of JMJD2D could not induce the expression of mTOR, HIF1α, HIF1β, and glycolytic genes, suggesting that the demethylase activity of JMJD2D is important for glycolysis through activating HIF1 signaling. Clinically, a highly positive correlation between the expression of JMJD2D and mTOR, HIF1β, and several glycolytic genes in human CRC specimens was identified. Collectively, our study reveals an important role of JMJD2D in CRC progression by enhancing glycolysis through activating HIF1 signaling pathway.

Steroid receptor coactivator 3 (SRC-3) is a transcriptional coactivator that interacts with nuclear receptors and some other transcription factors to enhance their effects on target gene transcription. We reported previously that SRC-3–deficient (SRC-3−/−) mice are extremely susceptible to Escherichia coli–induced septic peritonitis as a result of uncontrolled inflammation and a defect in bacterial clearance. In this study, we observed significant upregulation of SRC-3 in colonic epithelial cells in response to Citrobacter rodentium infection. Based on these findings, we hypothesized that SRC-3 is involved in host defense against attaching and effacing bacterial infection. We compared the responses of SRC-3−/− and wild-type mice to intestinal C. rodentium infection. We found that SRC-3−/− mice exhibited delayed clearance of C. rodentium and more severe tissue pathology after oral infection with C. rodentium compared with wild-type mice. SRC-3−/− mice expressed normal antimicrobial peptides in the colons but exhibited delayed recruitment of neutrophils into the colonic mucosa. Accordingly, SRC-3−/− mice showed a delayed induction of CXCL2 and CXCL5 in colonic epithelial cells, which are responsible for neutrophil recruitment. At the molecular level, we found that SRC-3 can activate the NF-κB signaling pathway to promote CXCL2 expression at the transcriptional level. Collectively, we show that SRC-3 contributes to host defense against enteric bacteria, at least in part via upregulating CXCL2 expression to recruit neutrophils.

The histone demethylase Jumonji domain containing 1A (JMJD1A) is overexpressed in multiple tumors and promotes cancer progression. JMJD1A has been shown to promote colorectal cancer (CRC) progression, but its molecular role in CRC is unclear. Here, we report that JMJD1A is overexpressed in CRC specimens and that its expression is positively correlated with that of proliferating cell nuclear antigen (PCNA). JMJD1A knockdown decreased the expression of proliferative genes such as c-Myc, cyclin D1, and PCNA, suppressed CRC cell proliferation, arrested cell cycle progression, and reduced xenograft tumorigenesis. Furthermore, JMJD1A knockdown inhibited CRC cell migration, invasion, and lung metastasis by decreasing matrix metallopeptidase 9 (MMP9) expression and enzymatic activity. Moreover, bioinformatics analysis of GEO profile datasets revealed that JMJD1A expression in human CRC specimens is positively correlated with the expression of Wnt/β-catenin target genes, including c-Myc, cyclin D1, and MMP9. Mechanistically, JMJD1A enhanced Wnt/β-catenin signaling by promoting β-catenin expression and interacting with β-catenin to enhance its transactivation. JMJD1A removed the methyl groups of H3K9me2 at the promoters of c-Myc and MMP9 genes. In contrast, the JMJD1A(H1120Y) variant, which lacked demethylase activity, did not demethylate H3K9me2 at these promoters, failed to assist β-catenin to induce the expression of Wnt/β-catenin target genes, and failed to promote CRC progression. These findings suggest that JMJD1A's demethylase activity is required for Wnt/β-catenin activation. Of note, high JMJD1A levels in CRC specimens predicted poor cancer outcomes. In summary, JMJD1A promotes CRC progression by enhancing Wnt/β-catenin signaling, implicating JMJD1A as a potential molecular target for CRC management.

Mycoepoxydiene (MED) is a polyketide isolated from a marine fungus associated with mangrove forest. It has been shown that MED has many kinds of effects such as anti-cancer and anti-inflammatory activities. However, its effects on anaphylaxis are still unknown. Mast cells play a pivotal role in IgE-mediated allergic response. Aggregation of the high affinity IgE receptor (FcεRI) on the surface of mast cell activates a cascade of signaling events leading to the degranulation and cytokine production in mast cells. Our study showed that MED could significantly suppress antigen-stimulated degranulation and cytokine production in mast cells and IgE-mediated passive cutaneous anaphylaxis (PCA) in mice. Furthermore, we found that MED suppressed antigen-induced activation of Syk, and subsequently inhibited the phosphorylation of PLCγ1, Akt, and MAPKs such as extracellular signal-regulated kinase (ERK), c-jun N-terminal kinase (JNK), and p38 in mast cells. Collectively, our study demonstrates that MED can inhibit the activation of mast cells and protect mice from mast cell-mediated allergic response through inhibiting the activation of Syk. These results suggest that MED is a potential compound for developing a promising anti-anaphylaxis drug.

Background General control non-depressible 5 (GCN5) is a crucial catalytic component of a transcriptional regulatory complex that plays important roles in cellular functions from cell cycle regulation to DNA damage repair. Although GCN5 has recently been implicated in certain oncogenic roles, its role in liver cancer progression remains vague. Results In this study, we report that GCN5 was overexpressed in 17 (54.8 %) of 31 human hepatocellular carcinoma (HCC) specimens. Down-regulation of GCN5 inhibited HCC cell proliferation and xenograft tumor formation. GCN5 knockdown decreased the protein levels of the proliferation marker proliferating cell nuclear antigen (PCNA) and amplified in breast cancer 1 (AIB1), but increased the protein levels of cell cycle inhibitor p21Cip1/Waf1 in HepG2 cells. GCN5 regulated AIB1 expression, at least in part, by cooperating with E2F1 to enhance AIB1 transcription. Consistently, GCN5 expression was positively correlated with AIB1 expression in human HCC specimens in two GEO profile datasets. Conclusion Since AIB1 plays a promoting role in HCC progression, our results propose that GCN5 promotes HCC progression at least partially by regulating AIB1 expression. This study implicates that GCN5 might be a potential molecular target for HCC diagnosis and treatment.

Summary The Sec14 protein (Sec14p) and its homologs are involved in the transfer of phosphatidylinositol/phosphatidylcholine phospholipids in eukaryotic cells. In the completely sequenced genome of Arabidopsis thaliana , multiple genes encoding putative Sec14p homologs have been predicted based on bioinformatic analysis. Here we report the identification of two yeast Sec14 -like genes (designated as AtSFH3 and AtSFH12 , respectively) that are predominately transcribed in Arabidopsis flowers. The deduced amino acid sequences of AtSfh3p and AtSfh12p exhibited high similarity to that of Sec14p. Ectopic expression of AtSfh3p or AtSfh12p corrected the high temperature sensitive phenotype caused by Sec14p functional deficiency in Saccharomyces cerevisiae , indicating that the two plant homologs are functional in the intracellular environment. AtSFH3 transcripts were detected in flowers, stems and immature siliques but not roots and leaves, with a relatively higher transcript level in the flowers. In contrast, AtSFH12 transcripts were only detectable in the flowers. Based on histochemical staining of β -glucuronidase (GUS) activities in the transgenic Arabidopsis plants harboring promoter∷GUS constructs, AtSFH3 transcription was first detected in the stigma papillae of the flowers at stage 11, and then in the pollen grains before and after fertilization. On the other hand, AtSFH12 transcription was only found in the mature and germinating pollen grains. The information from this study may provide useful clue for further analysis of the function of plant Sec14p homologs in the development of the male gametic cells and/or the fertilization process in higher plants.

// Ming Li 1, 2, 3, 4, * , Wei Wang 1, 3, * , Yuzhen Dan 1 , Zhangwei Tong 1 , Wenbo Chen 1 , Liping Qin 1 , Kun Liu 1, 5 , Wengang Li 2, 4 , Pingli Mo 1 , Chundong Yu 1, 2, 3 1 State Key Laboratory of Cellular Stress Biology, Innovation Center for Cell Signaling Network, School of Life Sciences, Xiamen University, Xiamen, China 2 Xiamen City Key Laboratory of Biliary Tract Diseases, Chenggong Hospital of Xiamen University, Xiamen, China 3 Engineering Research Center of Molecular Diagnostics, Ministry of Education, School of Life Sciences, Xiamen University, Xiamen, China 4 Department of Hepatobiliary Pancreas and Vessel Surgery, Chenggong Hospital of Xiamen University, Xiamen, China 5 Department of Pathology, Chenggong Hospital of Xiamen University, Xiamen, China * These authors contributed equally to this work Correspondence to: Chundong Yu, e-mail: cdyu@xmu.edu.cn Pingli Mo, e-mail: mop@xmu.edu.cn Keywords: sorafenib, AIB1, HCC, cell death, mRNA translation Received: October 14, 2015 Accepted: March 28, 2016 Published: April 18, 2016 ABSTRACT Multi-kinase inhibitor sorafenib represents a major breakthrough in the therapy of advanced hepatocellular carcinoma (HCC). Amplified in breast cancer 1 (AIB1) is frequently overexpressed in human HCC tissues and promotes HCC progression. In this study, we investigated the effects of sorafenib on AIB1 expression and the role of AIB1 in anti-tumor effects of sorafenib. We found that sorafenib downregulated AIB1 protein expression by inhibiting AIB1 mRNA translation through simultaneously blocking eIF4E and mTOR/p70S6K/RP-S6 signaling. Knockdown of AIB1 significantly promoted sorafenib-induced cell death, whereas overexpression of AIB1 substantially diminished sorafenib-induced cell death. Downregulation of AIB1 contributed to sorafenib-induced cell death at least in part through upregulating the levels of reactive oxygen species in HCC cells. In addition, resistance to sorafenib-induced downregulation of AIB1 protein contributes to the acquired resistance of HCC cells to sorafenib-induced cell death. Collectively, our study implicates that AIB1 is a molecular target of sorafenib and downregulation of AIB1 contributes to the anti-tumor effects of sorafenib.

Steroid receptor coactivator 1 (SRC-1) is a transcriptional coactivator not only for steroid receptors, such as androgen receptor and estrogen receptor, but also for other transcription factors. SRC-1 has been shown to play an important role in the progression of breast cancer and prostate cancer. However, its role in liver cancer progression remains unknown. In this study, we report that SRC-1 was overexpressed in 25 (62.5%) of 40 human hepatocellular carcinoma (HCC) specimens. Down-regulation of SRC-1 decreased HCC cell proliferation and impaired tumor maintenance in HCC xenografts. Knockdown of SRC-1 reduced protein levels of the proliferation marker proliferating cell nuclear antigen (PCNA) and the oncogene c-Myc. Knockout of SRC-1 in mice reduced diethylnitrosamine/CCl4-induced tumor formation in the liver and the expression of c-Myc and PCNA in liver tumors. SRC-1 promoted c-Myc expression, at least in part, by directly interacting with β-catenin to enhance Wnt/β-catenin signaling. Consistent with these results, the expression of SRC-1 was positively correlated with PCNA expression in human HCC specimens, and the expression levels of c-Myc in SRC-1-positive HCC specimens were higher than in SRC-1-negative HCC specimens. In addition, SRC-1 and SRC-3 were co-overexpressed in 47.5% of HCC specimens, and they cooperated to promote HCC cell proliferation. Simultaneous down-regulation of SRC-1 and SRC-3 dramatically inhibited HCC cell proliferation. Our results demonstrate that SRC-1 promotes HCC progression by enhancing Wnt/β-catenin signaling and suggest that SRC-1 is a potential therapeutic molecular target for HCC.

Activating transcription factor 3 (ATF3) is a common stress sensor, and its rapid induction by cellular stresses (e.g. DNA damage) is crucial for cells to mount appropriate responses (e.g. activating the tumor suppressor p53) and maintain homeostasis. Although emerging evidence suggests that dysregulation of ATF3 contributes to occurrences of human diseases including cancer, the mechanism(s) by which ATF3 expression is regulated is largely unknown. Here, we demonstrate that mouse double minute 2 (MDM2) is a bona fide E3 ubiquitin ligase for ATF3 and regulates ATF3 expression by promoting its degradation. MDM2 via its C-terminal RING finger can bind to the Basic region of ATF3 and mediate the addition of ubiquitin moieties to the ATF3 leucine zipper domain. As a consequence, ATF3, but not a mutant deficient in MDM2 binding (Delta80-100), is degraded by MDM2-mediated proteolysis. Consistent with these results, ablation of MDM2 in cells not only increases basal ATF3 levels, but results in stabilization of ATF3 in late stages of DNA damage responses. Because ATF3 was recently identified as a p53 activator, these results suggest that MDM2 could inactivate p53 through an additional feedback mechanism involving ATF3. Therefore, we provide the first evidence demonstrating that ATF3 is regulated by a posttranslational mechanism.

Genomic integration of human papillomavirus (HPV) DNA accounts for more than 90% of cervical cancers. High-risk genital HPVs encode E6 proteins that can interact with a cellular ubiquitin ligase E6-associated protein (E6AP) and target the tumor suppressor p53 for ubiquitin-mediated proteolysis. Currently, how this critical event is regulated is largely unknown. Here we report that activating transcription factor 3 (ATF3), a broad DNA damage sensor whose expression is frequently downregulated in cervical cancer, interacted with E6 and prevented p53 from ubiquitination and degradation mediated by the viral protein. Consistent with its role as a potent E6 antagonist, ATF3 expressed enforcedly in HPV-positive SiHa cells activated p53, leading to expression of p53-target genes (e.g. p21 and PUMA), cell cycle arrest and apoptotic cell death. The leucine zipper domain of ATF3 appears indispensable for these effects as an ATF3 mutant lacking this domain failed to interact with E6 and activate p53 in the cervical cancer cells. The prevention of p53 degradation was unlikely caused by binding of ATF3 to the tumor suppressor, but rather was a consequence of disruption of the E6-E6AP interaction by ATF3. These results indicate that ATF3 plays a key role in a mechanism defending against HPV-induced carcinogenesis, and could serve as a novel therapeutic target for HPV-positive cancers.

Background Steroid receptor coactivator 3 (SRC-3) is a multifunctional protein that plays an important role in malignancy of several cancers and in regulation of bacterial LPS-induced inflammation. However, the involvement of SRC-3 in allergic response remains unclear. Herein we used passive systemic anaphylaxis (PSA) and passive cutaneous anaphylaxis (PCA) mouse models to assess the role of SRC-3 in allergic response. Results SRC-3-deficient mice exhibited more severe allergic response as demonstrated by a significant drop in body temperature and a delayed recovery period compared to wild-type mice in PSA mouse model, whereas no significant difference was observed between two kinds of mice in PCA mouse models. Mast cells play a pivotal role in IgE-mediated allergic response. Antigen-induced aggregation of IgE receptor (FcϵRI) on the surface of mast cell activates a cascade of signaling events leading to the degranulation and cytokine production in mast cells. SRC-3-deficient bone marrow derived mast cells (BMMCs) developed normally but secreted more proinflammatory cytokines such as TNF-α and IL-6 than wild-type cells after antigen stimulation, whereas there was no significant difference in degranulation between two kinds of mast cells. Further studies showed that SRC-3 inhibited the activation of nuclear factor NF-κB pathway and MAPKs including extracellular signal-regulated kinase (ERK), c-jun N-terminal kinase (JNK), and p38 in antigen-stimulated mast cells. Conclusions Our data demonstrate that SRC-3 suppresses cytokine production in antigen-stimulated mast cells as well as PSA in mice at least in part through inhibiting NF-κB and MAPK signaling pathways. Therefore, SRC-3 plays a protective role in PSA and it may become a drug target for anaphylactic diseases.