LINC00982-encoded protein PRDM16-DT regulates CHEK2 splicing to suppress colorectal cancer metastasis and chemoresistance.

Metastasis is one of the key factors of treatment failure in late-stage colorectal cancer (CRC). Metastatic CRC frequently develops resistance to chemotherapeutic agents. This study aimed to identify the novel regulators from "hidden" proteins encoded by long noncoding RNAs (lncRNAs) involved in tumor metastasis and chemoresistance. Methods: CRISPR/Cas9 library functional screening was employed to identify the critical suppressor of cancer metastasis in highly invasive CRC models. Western blotting, immunofluorescence staining, invasion, migration, wound healing, WST-1, colony formation, gain- and loss-of-function experiments, in vivo experimental metastasis models, multiplex immunohistochemical staining, immunohistochemistry, qRT-PCR, and RT-PCR were used to assess the functional and clinical significance of FOXP3, PRDM16-DT, HNRNPA2B1, and L-CHEK2. RNA-sequencing, co-immunoprecipitation, qRT-PCR, RT-PCR, RNA affinity purification, RNA immunoprecipitation, MeRIP-quantitative PCR, fluorescence in situ hybridization, chromatin immunoprecipitation and luciferase reporter assay were performed to gain mechanistic insights into the role of PRDM16-DT in cancer metastasis and chemoresistance. An oxaliplatin-resistant CRC cell line was established by in vivo selection. WST-1, colony formation, invasion, migration, Biacore technology, gain- and loss-of-function experiments and an in vivo experimental metastasis model were used to determine the function and mechanism of cimicifugoside H-1 in CRC. Results: The novel protein PRDM16-DT, encoded by LINC00982, was identified as a cancer metastasis and chemoresistance suppressor. The down-regulated level of PRDM16-DT was positively associated with malignant phenotypes and poor prognosis of CRC patients. Transcriptionally regulated by FOXP3, PRDM16-DT directly interacted with HNRNPA2B1 and competitively decreased HNRNPA2B1 binding to exon 9 of CHEK2, resulting in the formation of long CHEK2 (L-CHEK2), subsequently promoting E-cadherin secretion. PRDM16-DT-induced E-cadherin secretion inhibited fibroblast activation, which in turn suppressed CRC metastasis by decreasing MMP9 secretion. Cimicifugoside H-1, a natural compound, can bind to LEU89, HIS91, and LEU92 of FOXP3 and significantly upregulated PRDM16-DT expression to repress CRC metastasis and reverse oxaliplatin resistance. Conclusions: lncRNA LINC00982 can express a new protein PRDM16-DT to function as a novel regulator in cancer metastasis and drug resistance of CRC. Cimicifugoside H-1 can act on the upstream of the PRDM16-DT signaling pathway to alleviate cancer chemoresistance.

Targeting ARF1-IQGAP1 interaction to suppress colorectal cancer metastasis and vemurafenib resistance.

INTRODUCTION: Acquired resistance to BRAF inhibitor vemurafenib is frequently observed in metastatic colorectal cancer (CRC), and it is a thorny issue that results in treatment failure. As adaptive responses for vemurafenib treatment, a series of cellular bypasses are response for the adaptive feedback reactivation of ERK signaling, which warrant further investigation. OBJECTIVES: We identified ARF1 (ADP-ribosylation factor 1) as a novel regulator of both vemurafenib resistance and cancer metastasis, its molecular mechanism and potential inhibitor were investigated in this study. METHODS: DIA-based quantitative proteomics and RNA-seq were performed to systematic analyze the profiling of vemurafenib-resistant RKO cells (RKO-VR) and highly invasive RKO cells (RKO-I8), respectively. Co­immunoprecipitation assay was performed to detect the interaction of ARF1 and IQGAP1 (IQ-domain GTPase activating protein 1). An ELISA-based drug screen system on FDA-approved drug library was established to screen the compounds against the interaction of ARF1-IQGAP1.The biological functions of ARF1 and LY2835219 were determined by transwell, western blotting, Annexin V-FITC/PI staining and in vivo experimental metastasis assays. RESULTS: We found that ARF1 strongly interacted with IQGAP1 to activate ERK signaling in VR and I8 CRC cells. Deletion of IQGAP1 or inactivation of ARF1 (ARF-T48S) restored the invasive ability induced by ARF1. As ARF1-IQGAP1 interaction is essential for ERK activation, we screened LY2835219 as novel inhibitor of ARF1-IQGAP1 interaction, which inactivated ERK signaling and suppressed CRC metastasis and vemurafenib-resistance in vitro and in vivo with no observed side effect. Furthermore, LY2835219 in combined treatment with vemurafenib exerted significantly inhibitory effect on ARF1-mediated cancer metastasis than used independently. CONCLUSION: This study uncovers that ARF1-IQGAP1 interaction-mediated ERK signaling reactivation is critical for vemurafenib resistance and cancer metastasis, and that LY2835219 is a promising therapeutic agent for CRC both as a single agent and in combination with vemurafenib.

Anti-allergic drug azelastine suppresses colon tumorigenesis by directly targeting ARF1 to inhibit IQGAP1-ERK-Drp1-mediated mitochondrial fission.

This study aimed to screen novel anticancer strategies from FDA-approved non-cancer drugs and identify potential biomarkers and therapeutic targets for colorectal cancer (CRC). Methods: A library consisting of 1056 FDA-approved drugs was screened for anticancer agents. WST-1, colony-formation, flow cytometry, and tumor xenograft assays were used to determine the anticancer effect of azelastine. Quantitative proteomics, confocal imaging, Western blotting and JC-1 assays were performed to examine the effects on mitochondrial pathways. The target protein of azelastine was analyzed and confirmed by DARTS, WST-1, Biacore and tumor xenograft assays. Immunohistochemistry, gain- and loss-of-function experiments, WST-1, colony-formation, immunoprecipitation, and tumor xenograft assays were used to examine the functional and clinical significance of ARF1 in colon tumorigenesis. Results: Azelastine, a current anti-allergic drug, was found to exert a significant inhibitory effect on CRC cell proliferation in vitro and in vivo, but not on ARF1-deficient or ARF1-T48S mutant cells. ARF1 was identified as a direct target of azelastine. High ARF1 expression was associated with advanced stages and poor survival of CRC. ARF1 promoted colon tumorigenesis through its interaction with IQGAP1 and subsequent activation of ERK signaling and mitochondrial fission by enhancing the interaction of IQGAP1 with MEK and ERK. Mechanistically, azelastine bound to Thr-48 in ARF1 and repressed its activity, decreasing Drp1 phosphorylation. This, in turn, inhibited mitochondrial fission and suppressed colon tumorigenesis by blocking IQGAP1-ERK signaling. Conclusions: This study provides the first evidence that azelastine may be novel therapeutics for CRC treatment. ARF1 promotes colon tumorigenesis, representing a promising biomarker and therapeutic target in CRC.

Identification of miR-515-3p and its targets, vimentin and MMP3, as a key regulatory mechanism in esophageal cancer metastasis: functional and clinical significance.

Metastasis is the main factor of treatment failure in cancer patients, but the underlying mechanism remains to be elucidated and effective new treatment strategies are urgently needed. This study aims to explore novel key metastasis-related microRNAs (miRNAs) in esophageal squamous cell carcinoma (ESCC). By comparing miRNA profiles of the highly metastatic ESCC cell sublines, we established through serial in vivo selection with the parental cells, we found that the expression level of miR-515-3p was lower in ESCC tumor tissues than adjacent normal tissues, further decreased in metastatic tumors, and moreover, markedly associated with advanced stage, metastasis and patient survival. The in vitro and in vivo assays suggested that miR-515-3p could increase the expression of the epithelial markers as well as decrease the expression of the mesenchymal markers, and more importantly, suppress invasion and metastasis of ESCC cells. Mechanistically, we revealed that miR-515-3p directly regulated vimentin and matrix metalloproteinase-3 (MMP3) expression by binding to the coding sequence and 3'untranslated region, respectively. In addition, the data from whole-genome methylation sequencing and methylation-specific PCR indicated that the CpG island within miR-515-3p promoter was markedly hypermethylated in ESCC cell lines and ESCC tumor tissues, which may lead to deregulation of miR-515-3p expression in ESCC. Furthermore, our preclinical experiment provides solid evidence that systemic delivery of miR-515-3p oligonucleotide obviously suppressed the metastasis of ESCC cells in nude mice. Taken together, this study demonstrates that miR-515-3p suppresses tumor metastasis and thus represents a promising prognostic biomarker and therapeutic strategy in ESCC.

Direct Targeting of CREB1 with Imperatorin Inhibits TGFß2-ERK Signaling to Suppress Esophageal Cancer Metastasis.

Metastasis accounts for 90% of cancer death worldwide, and effective therapeutic strategies are lacking. The aim of this work is to identify the key drivers in tumor metastasis and screen therapeutics for treatment of esophageal squamous cell carcinoma (ESCC). Gene Ontology analysis of The Cancer Genome Atlas (TCGA) gene expression datasets of ESCC patients with or without lympy metastasis identifies that TGFß2 is highly enriched in the pathways essential for tumor metastasis and upregulates in the metastatic ESCC tumors. High TGFß2 expression in ESCC correlates with metastasis and patient survival, and functionally contributes to tumor metastasis via activating extracellular signal-regulated kinases (ERK) signaling. By screening of a library consisting of 429 bioactive compounds, imperatorin is verified as a novel TGFß2 inhibitor, with robustly suppressive effect on tumor metastasis in multiple mice models. Mechanistically, direct binding of imperatorin and CREB1 inhibits phosphorylation, nuclear translocation of CREB1, and its interaction with TGFß2 promoter, represses TGFß2 expression and fibroblasts-secreted CCL2, and then inactivates ERK signaling to block cancer invasion and abrogates the paracrine effects of fibroblasts on tumor angiogenesis and metastasis. Overall, the findings suggest the use of TGFß2 as a diagnostic and prognostic biomarker and therapeutic target in ESCC, and supports the potential of imperatorin as a novel therapeutic strategy for cancer metastasis.

Adefovir dipivoxil sensitizes colon cancer cells to vemurafenib by disrupting the KCTD12-CDK1 interaction.

Vemurafenib is a B-Raf V600E inhibitor that exerts significant inhibitory effects in melanoma but not in colon cancer, and the mechanism of vemurafenib resistance remains unclear. In this study, bioinformatics analysis of gene profiles in cancer cells treated with vemurafenib or its analog revealed that cell cycle progression is significantly affected by vemurafenib. We found that CDK1 is stably activated in the vemurafenib-resistant (VR) colon cancer sublines that we established, indicating that CDK1 activation is responsible for vemurafenib resistance. As the KCTD12-CDK1 interaction is necessary for CDK1 activation, we screened an FDA-approved drug library consisting of 616 compounds and identified that adefovir dipivoxil (AD), a nucleoside analog for treatment of HBV infections, disrupts the CDK1-KCTD12 interaction and induces G2 phase arrest in the cell cycle. Functional assays demonstrated that AD significantly inhibited colon cancer cell proliferation and tumorigenesis both in vitro and in vivo with no observed side effects. Furthermore, AD sensitized vemurafenib-resistant colon cancer cells and tumor xenografts to vemurafenib. This study reveals that CDK1 activation induces vemurafenib resistance and that AD is a promising therapeutic strategy for colon cancer both as a single agent and in combination with vemurafenib.

Significance of integrin-linked kinase (ILK) in tumorigenesis and its potential implication as a biomarker and therapeutic target for human cancer.

Integrin-linked kinase (ILK), which is an ankyrin repeat-containing serine/threonine protein kinase, interacts with integrin ß1 and the ß3 cytoplasmic domain and phosphorylates integrin ß1. ILK has multiple functions in cells, such as cell-extracellular matrix interactions, cell cycle, apoptosis, cell proliferation and cell motility, which are associated with the interacting partners of ILK and downstream signaling pathways. Upregulation of ILK is frequently observed in cancer tissues compared to corresponding normal tissues. Emerging evidence has demonstrated that ILK plays an important role in biological processes associated with tumorigenesis, including cancer cell proliferation, angiogenesis, metastasis, and drug resistance. Furthermore, inhibition of ILK expression and activity using siRNA or chemical inhibitors has shown a significant suppressive effect on cancer development and progression, implicating the potential of ILK as a target for cancer treatment. In this review, we summarized the functional role of ILK in tumorigenesis, with the expectation that targeting ILK could provide more evidence for cancer therapy.

Comparative Proteomics Analysis Identifies Cdc42-Cdc42BPA Signaling as Prognostic Biomarker and Therapeutic Target for Colon Cancer Invasion.

Metastasis is one of the major causes of treatment failure in the patients with colon cancer. The aim of our study is to find key proteins and pathways that drive invasion and metastasis in colon cancer. Eight rounds of selection of cancer cells invading through matrigel-coated chamber were performed to obtain highly invasive colon cancer sublines HCT116-I8 and RKO-I8. Stable Isotope Labeling by Amino Acids in Cell Culture technology was used to identify the differently expressed proteins, and the proteomics data were analyzed by ingenuity pathway analysis. PAK1-PBD immunoprecipitation combined with Western blot were carried out to determine Cdc42 activity, and qRT-PCR and Western blot were used to determine gene expression. The functional role of Cdc42BPA and Cdc42 pathway in colon cancer invasion was studied by loss-of-function experiments including pharmacological blockade, siRNA knockdown, chamber invasion, and WST-1 assays. Human colon cancer tissue microarray was analyzed by immunohistochemistry for overexpression of Cdc42BPA and its correlation with clinicopathological parameters and patient survival outcomes. HCT116-I8 and RKO-I8 cells showed significantly stronger invasive potential as well as decreased E-cadherin and increased vimentin expressions compared with parental cells. The differently expressed proteins in I8 cells compared with parental cells were identified. Bioinformatics analysis of proteomics data suggested that Cdc42BPA protein and Cdc42 signaling pathway are important for colon cancer invasion, which was confirmed by experimental data showing upregulation of Cdc42BPA and higher expression of active GTP-bound form of Cdc42 in HCT116-I8 and RKO-I8 cells. Functionally, pharmacological and genetic blockade of Cdc42BPA and Cdc42 signaling markedly suppressed colon cancer cell invasion and reversed epithelial mesenchymal transition process. Furthermore, compared with adjacent normal tissues, Cdc42BPA expression was significantly higher in colon cancer tissues and further upregulated in metastatic tumors in lymph nodes. More importantly, Cdc42BPA expression was correlated with metastasis and poor survival of the patients with colon cancer. This study provides the first evidence that Cdc42BPA and Cdc42 signaling are important for colon cancer invasion, and Cdc42BPA has potential implications for colon cancer prognosis and treatment.

Significance of PI3K/AKT signaling pathway in metastasis of esophageal squamous cell carcinoma and its potential as a target for anti-metastasis therapy.

Metastasis is the most lethal hallmark of esophageal squamous cell carcinoma (ESCC). The aim of the study is to identify key signaling pathways that control metastasis in ESCC. Highly invasive ESCC sublines (designated I3 cells) were established through three rounds of selection of cancer cells invading through matrigel-coated chambers. Gene expression profile of one of the I3 sublines was compared with that of its parental cell line using cDNA microarray analysis. Gene ontology and pathway analyses of the differentially expressed genes (both upregulated and downregulated) indicated that genes associated with cellular movement and the AKT pathway were associated with increased cancer cell invasiveness. Western blot analysis confirmed increased phosphorylated AKT (p-AKT), N-cadherin and decreased E-cadherin expression in the I3 cells. Immunohistochemistry was used to evaluate the clinical significance of p-AKT expression in ESCC, and the results showed higher p-AKT nuclear expression in lymph node metastases when compared with primary carcinoma. Inactivation of the PI3K/AKT pathway with specific inhibitors, or with PTEN overexpression, resulted in reversed cadherin switching and inhibited cancer cell motility. Inhibition of the pathway by treatment with wortmannin markedly suppressed experimental metastasis in nude mice. Our data demonstrated the importance of the PI3K/AKT signaling pathway in ESCC metastasis and support PI3K/AKT as a valid therapeutic target in treatment of metastatic ESCC.

Inhibition of Nrf2 enhances the anticancer effect of 6-O-angeloylenolin in lung adenocarcinoma.

6-O-Angeloylenolin (6-OA), a sesquiterpene lactone isolated from Centipeda minima (L.) A. Br. (Compositae), has been used to treat respiratory diseases for centuries. However, whether and how 6-OA exerts anticancer effects against lung cancer remains to be elucidated. In this study, we showed that 6-OA markedly suppressed the cell viability and colony formation of lung cancer cells H1299 and A549, with no significant toxic effect on non-cancer cells HBE. Annexin V/7-AAD assay revealed that 6-OA induced cell apoptosis in dose- and time-dependent manners, which was further confirmed by the increased expression of cleaved caspase-3. To uncover the molecular mechanism how 6-OA exerts its anticancer effects, SILAC quantitative proteomics was performed to identify 6-OA-regulated proteins in lung cancer cells. Ingenuity Pathway Analysis revealed that these 6-OA-regulated proteins were mainly involved in Nrf2-mediated oxidative stress response, which was confirmed by the nuclear translocation of Nrf2 upon 6-OA treatment. Moreover, we found that 6-OA stimulated the accumulation of reactive oxygen species (ROS), whereas inhibition of ROS generation with N-acetyl l-cysteine could block the 6-OA-induced anticancer effects. Furthermore, blockade of cellular anti-oxidative system by Nrf2 knockdown significantly augmented the 6-OA-induced apoptosis. Taken together, we demonstrated that 6-OA exerts its anticancer effects by generating ROS, and inhibition of Nrf2 anti-oxidative system potentiated these effects. These results suggest that 6-OA may be used to treat lung cancer, with better outcome by combining with Nrf2 inhibitor to block Nrf2 pathway.

[Intercepting effects of seven Chinese herb drugs on experimental oral carcinogenesis].

PURPOSE: To screen effective chemopreventive Chinese herb drugs on experimental oral carcinogenesis. METHODS: 410 golden hamsters were randomly divided into positive control group,negative control group and 7 experimental groups(Radix et Rhizoma Thalictri, Radix Sophorae Tonkinesis, Pseudobulbus Cremastrae appendiculate, Rhizoma Acori Tatarinowii, Radix Angelicae seu Heraclei, Rhizoma Curcumae, Fructus Trichosanthis). 7,12-Dimethylbenz(a)anthracene(DMBA) was used to induce oral carcinogenesis in hamster cheek pouch, 7 liquid Chinese herb drugs were respectively injected into the stomach of the hamsters before and during oral carcinogenesis. Specimens were observed by histopathologic method, and the results were analysized statistically. RESULTS: Compared with positive control group, the prevalence of displasia was significantly reduced in group Radix Sophorae Tonkinesis and Radix Angelicae Dahuricae, but significant decrease could not be found in other experiment groups. CONCLUSION: Radix Sophorae Tonkinesis and Radix Angelicae Dahuricae could effectively intercept DMBA-induced oral carcinogenesis in hamster.