Yili Yang

Liver metastasis is the most common form of metastatic colorectal cancers during the course of the disease. The global change in protein abundance in liver metastatic colorectal cancers and its role in metastasis establishment have not been comprehensively analyzed. In the present study, fresh-frozen tissue samples including normal colon/localized/liver metastatic CRCs from each recruited patient were analyzed by quantitative proteomics using a multiplexed TMT labeling strategy. Around 5000 protein groups were quantified from all samples. The proteomic profile of localized/metastatic CRCs varied greatly from that of normal colon tissues; differential proteins were mainly from extracellular regions and participate in immune activities, which is crucial for the chronic inflammation signaling pathways in the tumor microenvironment. Further statistical analysis revealed 47 proteins exhibiting statistical significance between localized and metastatic CRCs, of which FILI1P1 and PLG were identified for the first time in proteomic data, which were highly associated with liver metastasis in CRCs.

Chemokine‐like factor (CKLF)‐like, MAL and related proteins for vesicle trafficking and membrane link (MARVEL) transmembrane domain‐containing family proteins (CMTMs) have significant roles in the immune system, in male reproduction, as well as in tumorigenesis. Previous studies have shown that CMTM family member 7 (CMTM7) was broadly expressed in various normal tissues, but not in lung, gastric, esophageal, pancreas, and cervix cancers. To explore its relationship with liver cancer, we examined the expression of CMTM7 in liver cancers and its correlation with clinical and pathological conditions. We found that CMTM7 expression was markedly reduced in liver cancer tissues, and negatively correlated with TNM staging and tumor metastasis. In vitro studies showed that enforced expression of CMTM7 inhibited the cell growth and migration of liver cancer cells. Further analysis revealed that CMTM7 suppressed AKT signaling and induced cell cycle arrest at the G0/G1 phase in the liver cancer cells, likely as the consequent of decreased levels of cyclin D1, cyclin‐dependent kinase 4 (CDK4), and CDK6, and increased p27 expression. Thus, CMTM7 functions as a tumor suppressor in liver cancer through suppressing cell cycle progression.

Previous literatures reported insulin‐like growth factor‐2 messenger RNA‐binding protein 3 (IGF2BP3) is a poor prognostic marker for colorectal cancer (CRC) patients. However, basic research on the effect and biological role of IGF2BP3 in CRC was still scare. Real‐time quantitative polymerase chain reaction and western blot analysis were used to examine IGF2BP3 expression level in tumors and paired normal tissues from CRC patients. Tissue microarrays with 192 CRC patients were subjected to immunohistochemical staining to analyze the prognostic value of IGF2BP3. Proliferation assays, migration assays, and xenograft tumor formation in nude mice were performed to assess the biological role of IGF2BP3 in CRC cells. IGF2BP3 expression was significantly upregulated in tumor tissues compared with the matched normal tissues both in messenger RNA and protein level and was associated with worse prognosis. IGF2BP3 knockdown made cell cycle arrest to impair the proliferation ability of CRC cells and further inhibited the xenograft tumor growth in nude mice, also inhibited the migration ability of CRC cells via inducing epithelial–mesenchymal transition. Therefore, the research demonstrated that increased IGF2BP3 expression promoted the aggressive phenotypes of CRC cells. Targeted IGF2BP3 could be a novel and effective gene therapy for CRC patients to make a better prognosis.

Increased adipocytes are associated with obesity and many human disorders including cancers. To further understand the molecular mechanisms of adipogenesis, transcriptome sequencing was performed to find genes involved in the adipogenic differentiation of human adipose-derived stem cells (hASCs). The mRNA of taurine transporter (TauT, also known as SLC6A6) was found significantly upregulated in hASCs undergoing differentiation. TauT expression was also markedly increased in fat tissues from obese mice induced by high fat diet or genetic mutations (ob/ob and db/db mice). In vitro, downregulation of TauT attenuated effectively the adipogenic differentiation of hASCs, and TauT overexpression promoted the formation of adipocytes. Among the molecules transported by TauT, hypotaurine and β-alanine promoted adipocyte formation, whereas taurine inhibited the process. Moreover, the inhibitory effect of TauT knockdown on hASCs differentiation was largely reversed by hypotaurine and β-alanine through promoting the downregulation of β-catenin. These results indicated that TauT regulate adipocyte formation through transported amino acids and may serve as a target for therapeutic intervention of obesity.

We and others have previously shown that the STAT3 signaling pathway is activated in some esophageal squamous cell carcinoma (ESCC) cells and is required for the survival and growth of these primary ESCC-derived xenografts. It has also been shown that the natural polyphenol curcumin is an effective anti-tumor agent. Luciferase assay and immunoblotting were performed to examine whether curcumin suppressed STAT3 signaling. CCK-8 assay and xenografts were utilized for analyzing ESCC cell growth in culture and mice. Soft agar assay was carried out to determine the colony formation ability of ESCC cells in the presence or absence of curcumin. Cell death and cell cycle were assessed by In CELL Analyzer 2000. Immunohistochemistry and TUNEL assay were used for detecting apoptosis in ESCC tisuses. Molecular docking was performed to evaluate the interaction of curcumin with JAK2. JAK2 activity was assessed using an in vitro cell-free system. HE staining was used to evaluate the ESCC tissues. The natural polyphenol curcumin inhibited STAT3 phosphorylation rapidly and blocked STAT3-mediated signaling in ESCC cells. It also induced growth arrest and apoptosis in cultured ESCC cells, which were attenuated by enforced expression of STAT3. Furthermore, curcumin preferentially blocked the growth of primary ESCC-derived xenografts that harbored activated STAT3. Curcumin is able to exert anti-tumor action through inhibiting the STAT3 signaling pathway. Giving its wide use in traditional medicines with low toxicity and few adverse reactions, it is conceivable that curcumin might be further explored as a unique STAT3 inhibitor for anti-cancer therapies.

Nuclear factor kappa B (NF‐κB) signaling pathway is activated in many colorectal cancer (CRC) cells and in the tumor microenvironment, which plays a critical role in cancer initiation, development, and response to therapies. In the present study, we found that the widely used antimalarial drug mefloquine was a NF‐κB inhibitor that blocked the activation of IκBα kinase, leading to reduction of IκBα degradation, decrease of p65 phosphorylation, and suppressed expression of NF‐κB target genes in CRC cells. We also found that mefloquine induced growth arrest and apoptosis of CRC cells harboring phosphorylated p65 in culture and in mice. Furthermore, expression of constitutive active IKKβ kinase significantly attenuated the cytotoxic effect of the compound. These results showed that mefloquine could exert antitumor action through inhibiting the NF‐κB signaling pathway, and indicated that the antimalarial drug might be repurposed for anti‐CRC therapy in the clinic as a single agent or in combination with other anticancer drugs.

Constitutive activated STAT3 is an essential regulator and therapeutic target in esophageal squamous cell carcinoma Constitutive activated STAT3 is an essential regulator and therapeutic target in esophageal squamous cell carcinoma

Although proteasome inhibitors such as bortezomib had significant therapeutic effects in multiple myeloma and mantel cell lymphoma, they exhibited minimal clinical activity as a monotherapy for solid tumors, including colorectal cancer. We found in this study that proteasome inhibition induced a remarkable nuclear exportation of ubiquitinated proteins. Inhibition of CRM1, the nuclear export carrier protein, hampered protein export and synergistically enhanced the cytotoxic action of bortezomib on colon cancer cells containing wild-type p53, which underwent G2–M cell-cycle block and apoptosis. Further analysis indicated that tumor suppressor p53 was one of the proteins exported from nuclei upon proteasome inhibition, and in the presence of CRM1 inhibitor KPT330, nuclear p53, and expression of its target genes were increased markedly. Moreover, knockdown of p53 significantly reduced the synergistic cytotoxic action of bortezomib and KPT330 on p53+/+ HCT116 cells. In mice, KPT330 markedly augmented the antitumor action of bortezomib against HCT116 xenografts as well as patient-derived xenografts that harbored functional p53. These results indicate that nuclear p53 is a major mediator in the synergistic antitumor effect of bortezomib and KPT330, and provides a rationale for the use of proteasome inhibitor together with nuclear export blocker in the treatment of colorectal cancer. It is conceivable that targeting nuclear exportation may serve as a novel strategy to overcome resistance and raise chemotherapeutic efficacy, especially for the drugs that activate the p53 system. Mol Cancer Ther; 16(4); 717–28. ©2016 AACR.