Lung cancer, one of the leading causes of death worldwide, is often associated with a state of immune suppression, but the molecular and functional basis remains enigmatic. Evidence is provided in this paper supporting the role of lung cancer-derived soluble lectin, galectin-1, as a culprit in dendritic cell (DC) anergy. We have shown that galectin-1 is highly expressed in lung cancer cell lines, together with the serum and surgical samples from lung cancer patients. Functionally, lung cancer-derived galectin-1 has been shown to alter the phenotypes of monocyte-derived DCs (MdDCs) and impair alloreactive T cell response, concomitant with the increase of CD4+CD25+FOXP3+ regulatory T cells. The regulatory effect of galectin-1 is mediated, in part, through its ability to induce, in an Id3 (inhibitor of DNA binding 3)-dependent manner, the expression of IL-10 in monocytes and MdDCs. This effect is inhibited by the addition of lactose, which normalizes the phenotypic and functional alterations seen in MdDCs. Of note, significant upregulation of IL-10 was seen in tumor-infiltrating CD11c+ DCs in human lung cancer samples. This was also noted in mice transplanted with lung cancer cells, but not in those receiving tumor cells with galectin-1 knockdown. Furthermore, a significant reduction was noted in lung cancer incidence and in the levels of IL-10–expressing, tumor-infiltrating DCs, in mice receiving galectin-1–silenced tumor cells. These results thus suggest that the galectin-1/IL-10 functional axis may be crucial in lung cancer-mediated immune suppression, and that galectin-1 may serve as a target in the development of lung cancer immunotherapy.

Autophagy plays diverse roles in Ras-related tumorigenesis. H-ras(val12) induces autophagy through multiple signaling pathways including Raf-1/ERK pathway, and various ERK downstream molecules of autophagy have been reported. In this study, Bcl-2/adenovirus E1B 19-kDa-interacting protein 3 (BNIP3) is identified as a downstream transducer of the Ras/Raf/ERK signaling pathway to induce autophagy. BNIP3 was upregulated by H-ras(val12) at the transcriptional level to compete with Beclin 1 for binding with Bcl-2. H-ras(val12)-induced autophagy suppresses cell proliferation demonstrated both in vitro and in vivo by expression of ectopic BNIP3, Atg5, or interference RNA of BNIP3 (siBNIP3) and Atg5 (shAtg5) using mouse NIH3T3 and embryo fibroblast cells. H-ras(val12) induces different autophagic responses depending on the duration of Ras overexpression. After a short time (48 hours) of Ras overexpression, autophagy inhibits cell proliferation. In contrast, a longer time (2 weeks) of Ras overexpression, cell proliferation was enhanced by autophagy. Furthermore, overexpression of mutant Ras, BNIP3, and LC3-II was detected in bladder cancer T24 cells and the tumor parts of 75% of bladder cancer specimens indicating a positive correlation between autophagy and tumorigenesis. Taken together, our mouse model demonstrates a balance between BNIP3-mediated autophagy and H-ras(val12)-induced tumor formation and reveals that H-ras(val12) induces autophagy in a BNIP3-dependent manner, and the threshold of autophagy plays a decisive role in H-ras(val12)-induced tumorigenesis. Our findings combined with others' reports suggest a new therapeutic strategy against Ras-related tumorigenesis by negative or positive regulation of autophagic activity, which is determined by the level of autophagy and tumor progression stages.

Chemotherapeutic agents- and radiation therapy-induced NF-κB activation in cancer cells contributes to aggressive tumor growth and resistance to chemotherapy and ionizing radiation during cancer treatment. TAK1 has been shown to be required for genotoxic stress-induced NF-κB activation. However, whether TAK1 ubiquitination is involved in genotoxic stress-induced NF-κB activation remains unknown. Herein, we demonstrate that TAK1 ubiquitination plays an important role in the positive and negative regulation of Doxorubicin (Dox)-induced NF-κB activation. We found that TAK1 was required for Dox-induced NF-κB activation. At the early stage of Dox treatment, Dox induced Lys63-linked TAK1 polyubiquitination at lysine 158 residue. USP4 inhibited Dox-induced TAK1 Lys63-linked polyubiquitination and knockdown of USP4 enhanced Dox-induced NF-κB activation. At the late stage of Dox treatment, Dox induced Lys48-linked TAK1 polyubiquitination to promote TAK1 degradation. ITCH inhibited Dox-induced NF-κB activation by promoting Lys48-linked TAK1 polyubiquitination and its subsequent degradation. Our study indicates that TAK1 ubiquitination plays critical roles in the regulation of Dox-induced NF-κB activation. Thus, intervention of TAK1 kinase activity or TAK1 Lys63-linked polyubiquitination pathways might greatly enhance the therapeutic efficacy of Dox.

BackgroundMutant Ras plays multiple functions in tumorigenesis including tumor formation and metastasis. Reversion-inducing cysteine-rich protein with Kazal motifs (RECK), a metastasis inhibitor gene, suppresses matrix metalloproteinase (MMP) activity in the metastatic cascade. Clarifying the relationship between Ras and RECK and understanding the underlying molecular mechanism may lead to the development of better treatment for Ras-related tumors.MethodsSuppression subtractive hybridization PCR (SSH PCR) was conducted to identify Ha-rasval12 up-regulated genes in bladder cancer cells. Stable cell lines of human breast cancer (MCF-7-ras) and mouse NIH3T3 fibroblasts (7–4) harboring the inducible Ha-rasval12 oncogene, which could be induced by isopropylthio-β-D-galactoside (IPTG), were used to clarify the relationship between Ras and the up-regulated genes. Chromatin immunoprecipitation (ChIP) assay, DNA affinity precipitation assay (DAPA) and RECK reporter gene assay were utilized to confirm the complex formation and binding with promoters.ResultsRetinoblastoma binding protein-7 (RbAp46) was identified and confirmed as a Ha-rasval12 up-regulated gene. RbAp46 could bind with histone deacetylase (HDAC1) and Sp1, followed by binding to RECK promoter at the Sp1 site resulting in repression of RECK expression. High expression of Ras protein accompanied with high RbAp46 and low RECK expression were detected in 75% (3/4) of the clinical bladder cancer tumor tissues compared to the adjacent normal parts. Ras induced RbAp46 expression increases invasion of the bladder cancer T24 cells and MMP-9 activity was increased, which was confirmed by specific lentiviral shRNAs inhibitors against Ras and RbAp46. Similarly, knockdown of RbAp46 expression in the stable NIH3T3 cells “7-4” by shRNA decreased Ras-related lung metastasis using a xenograft nude mice model.ConclusionsWe confirmed that RbAp46 is a Ha-rasval12 up-regulated gene and binds with HDAC1 and Sp1. Furthermore, RbAp46 binds to the RECK promoter at the Sp1 site via recruitment by Sp1. RECK is subsequently activated, leading to increased MMP9 activity, which may lead to increased metastasis in vivo. Our findings of Ras upregulation of RbAp46 may lead to revealing a novel mechanism of Ras-related tumor cell metastasis.Electronic supplementary materialThe online version of this article (doi:10.1186/s12885-015-1155-7) contains supplementary material, which is available to authorized users.