Promotes Cancer Cell Metastasis Research Articles

A Zebrafish Model Discovers a Novel Mechanism of Stromal Fibroblast-Mediated Cancer Metastasis.

Purpose: Cancer metastasis can occur at the early stage of tumor development when a primary tumor is at the microscopic size. In particular, the interaction of malignant cells with other cell types including cancer-associated fibroblasts (CAF) in promoting metastasis at the early stage of tumor development remains largely unknown. Here, we investigated the role of CAFs in facilitating the initial events of cancer metastasis when primary tumors were at microscopic sizes.Experimental Design: Multicolor-coded cancer cells and CAFs were coimplanted into the transparent zebrafish body and metastasis at a single-cell level was monitored in living animals. Healthy fibroblasts, tumor factor-educated fibroblasts, and CAFs isolated from various tumors were tested for their ability to facilitate metastasis.Results: We showed that CAFs promoted cancer cell metastasis at the very early stage during primary tumor development. When a primary tumor was at the microscopic size consisting of a few hundred cells, CAFs were able to hijack cancer cells for dissemination from the primary site. Surprisingly, a majority of metastatic cancer cells remained in tight association with CAFs in the circulation. Furthermore, stimulation of non-metastasis-promoting normal fibroblasts with TGF-B, FGF-2, HGF, and PDGF-BB led to acquisition of their metastatic capacity.Conclusions: Cancer metastasis occurs at the very early stage of tumor formation consisting of only a few hundred cells. CAFs are the key cellular determinant for metastasis. Our findings provide novel mechanistic insights on CAFs in promoting cancer metastasis and targeting CAFs for cancer therapy should be aimed at the early stage during cancer development. Clin Cancer Res; 23(16); 4769-79. ©2017 AACR.

Chitosan Nanoparticles Promoted Cancer Cell Invasion and Metastasis via the Massive Production of Reactive Oxygen Species

Chitosan Nanoparticles Promoted Cancer Cell Invasion and Metastasis via the Massive Production of Reactive Oxygen Species

CD147 functions as the signaling receptor for extracellular divalent copper in hepatocellular carcinoma cells.

Elevated copper levels in tumor microenvironment are directly correlated to cancer progression in a variety of malignancies. Copper is required in angiogenesis, and promotes the proliferation and metastasis of cancer cells. However, the molecular mechanism of copper in promoting cancer progression remains elusive. Here we report that CD147 serves as a signaling receptor for extracellular Cu2+ in hepatocellular carcinoma (HCC) cells. Cu2+ binds to the extracellular membrane-proximal domain of CD147 and mediates its self-association. Cu2+-mediated self-association of CD147 activates PI3K/Akt signaling pathway leading to the up-regulation of matrix metalloproteinase MMP-2 and MMP-14 in HCC cells. Cu2+-induced CD147 self-association also enhances the ability of HCC cells to stimulate MMP-2 expression from neighboring fibroblasts, as well as increases the invasiveness of HCC cells which is abolished by the copper chelator tetrathiomolybdate. We have mapped the interfaces and identified the key residues of CD147 involved in the Cu2+ induced self-association. The Cu2+ binding deficient CD147 mutant abolishes the stimulating effects of Cu2+ on HCC cells. Our study reveals a novel extracellular signaling role of copper in promoting cancer cell metastasis, which implies that targeting the Cu2+-induced self-association of CD147 is a new strategy for cancer treatment.

TM4SF1 Promotes Metastasis of Pancreatic Cancer via Regulating the Expression of DDR1

Transmembrane-4-L-six-family-1(TM4SF1), a four-transmembrane L6 family member, is highly expressed in various pancreatic cancer cell lines and promotes cancer cells metastasis. However, the TM4SF1-associated signaling network in metastasis remains unknown. In the present study, we found that TM4SF1 affected the formation and function of invadopodia. Silencing of TM4SF1 reduced the expression of DDR1 significantly in PANC-1 and AsPC-1 cells. Through double fluorescence immuno-staining and Co-immunoprecipitation, we also found that TM4SF1 colocalized with DDR1 and had an interaction with DDR1. In addition, upregulating the expression of DDR1 rescued the inhibitory effects of cell migration and invasion, the expression of MMP2 and MMP9 and the formation and function of invadopodia when TM4SF1 silenced. In pancreatic cancer tissues, qRT-PCR and scatter plots analysis further determined that TM4SF1 had a correlation with DDR1. Collectively, our study provides a novel regulatory pathway involving TM4SF1, DDR1, MMP2 and MMP9, which promotes the formation and function of invadopodia to support cell migration and invasion in pancreatic cancer.

Long noncoding RNA HOTAIR promotes metastasis of renal cell carcinoma by up-regulating histone H3K27 demethylase JMJD3.

Long Noncoding RNAs (lncRNAs) are a kind of non-protein coding transcripts longer than 200 nucleotides, and play important roles in diverse biological processes, such as embryonic development and apoptosis. Homeobox (HOX) transcript antisense intergenic RNA (HOTAIR) is a negative prognostic factor in a variety of human cancers, such as breast, liver and lung cancers. HOTAIR can promote cancer cell metastasis by reprogramming chromatin organization. In the present study, HOTAIR expression was elevated in tissues of renal cell carcinoma compared to adjacent normal tissues, and positively correlated with metastasis (P<0.05). The cell migration was inhibited in scratch test and transwell assay after HOTAIR knockdown (P<0.05). Further researches revealed that histone demethylase JMJD3 was reduced and its target gene Snai1 expression was down-regulated after HOTAIR suppression (P<0.05). Meanwhile, the level of histone methytransferase EZH2 target gene PCDHB5 was increased (P<0.05). Collectively, these data suggest that HOTAIR is an important promoter in metastasis of renal cell carcinoma and also plays a dual regulatory role in chromatin state by effecting both histone metylation and demethylation at different gene loci.

MiR-125a-5p decreases after long non-coding RNA HOTAIR knockdown to promote cancer cell apoptosis by releasing caspase 2.

HOTAIR (homeobox transcript antisense RNA), one of the prototypical long non-coding RNAs, has been verified overexpressed in multiple carcinomas and has emerged as a promising novel anticancer target. Its well-established role is acting as a predictor of poor prognosis and promoting cancer cell metastasis. Recently, another important mission of HOTAIR was uncovered that targeting HOTAIR caused cancer cell apoptosis. Nevertheless, so far there is no published data elaborating the mechanism. Here, we report that microRNA miR-125a-5p decreases and releases caspase 2 to promote cancer cell apoptosis after HOTAIR knockdown. We applied siRNAs targeting HOTAIR to various cancer cells, and observed apoptosis in all of these cell lines. RNA sequencing detected that miR-125a-5p was decreased after HOTAIR knockdown and miR-125a-5p mimics could rescue the apoptosis induced by HOTAIR deficiency. Luciferase assays identified caspase 2, an initiator caspase, to be a new target of miR-125a-5p. Elevated expression and subsequent cleavage of caspase 2 was observed after HOTAIR knockdown or inhibition of miR-125a-5p. RNAi of caspase 2 could attenuate the apoptosis induced by HOTAIR knockdown. In 80 clinical colon cancer tissues, HOTAIR and miR-125a-5p levels were higher than adjacent tissues, whereas caspase 2 was lower. MiR-125a-5p expression level was significantly correlated with colon tumor size, lymph node metastasis and clinical stage. These findings indicate that miR-125a-5p decreases after HOTAIR knockdown to promote cancer cell apoptosis by releasing caspase 2. Our work reveals a previously unidentified apoptotic mechanism, which might be exploitable in anticancer drug development.

AFAP1-AS1, a long noncoding RNA upregulated in lung cancer and promotes invasion and metastasis.

Long noncoding RNAs (lncRNAs) have emerged as a major regulator of cancer. Significant fraction of lncRNAs is represented on widely used microarray platforms; however, many of which have no known function. To discover novel lung cancer-related lncRNAs, we analyzed the lncRNA expression patterns in five sets of previously published lung cancer gene expression profile data that were represented on Affymetrix HG-U133 Plus 2.0 array, and identified dysregulated lncRNAs in lung cancer. One lncRNA, actin filament associated protein 1 antisense RNA1 (AFAP1-AS1), was the most significantly upregulated in lung cancer and associated with poor prognosis. In vitro experiments demonstrated that AFAP1-AS1 knockdown significantly inhibited the cell invasive and migration capability in lung cancer cells. AFAP1-AS1 knockdown also increased the expression of its antisense protein coding gene, actin filament associated protein 1 (AFAP1), and affected the expression levels of several small GTPase family members and molecules in the actin cytokeratin signaling pathway, which suggested that AFAP1-AS1 promoted cancer cell metastasis via regulation of actin filament integrity. Our findings extend the number of noncoding RNAs functionally implicated in lung cancer progression and highlight the role of AFAP1-AS1 as potential prognostic biomarker and therapeutic target of lung cancer.

P0017 S100P regulates cytoskeleton dynamics to promote cell migration and metastasis

Background S100P is an EF-hand calcium-binding protein. Like S100A4 and S100A6, S100P is expressed at a high level in cancers, particularly in those of the prostate, pancreas, and breast. We have demonstrated that S100P is a metastasis-inducing protein and that its upregulation enhances cell migration. When studying the molecular mechanisms, we found that S100P interacts separately with two major components of cytoskeleton, non-muscle myosin IIA (NMIIA) and tubulin. The aim of this study was to understand how S100P enhances cell migration through these protein interactions. Methods S100P-inducible cell lines and specific siRNAs were used to control the expression of S100P in cells. We used specific chemicals to disrupt actin stress fibres and microtubules and peptides to block the protein interactions. Results S100P differentially regulates NMIIA and NMIIB filaments, which reduced cell adhesion and enhanced cell migration. This process involves Rho, RAC1, and focal adhesion kinase. S100P upregulation simultaneously altered the dynamics of tubulin polymerisation to facilitate cell migration. Interpretation S100P directly regulates the dynamics of both actin-myosin filaments and microtubules, and the co-regulation of these cytoskeletons may synergistically enhance cell migration and promote cancer cell metastasis.

Upregulated long non-coding RNA AFAP1-AS1 expression is associated with progression and poor prognosis of nasopharyngeal carcinoma.

Altered expression of long noncoding RNAs (lncRNAs) associated with human carcinogenesis. We performed a cDNA microarray analysis of lncRNA expression in 12 cases of nasopharyngeal carcinoma (NPC) and 4 non-tumor nasopharyngeal epitheliums. One lncRNA, actin filament associated protein 1 antisense RNA1 (AFAP1-AS1), was identified and selected for further study. AFAP1-AS1 expression was upregulated in NPC and associated with NPC metastasis and poor prognosis. In vitro experiments demonstrated that AFAP1-AS1 knockdown significantly inhibited the NPC cell migration and invasive capability. AFAP1-AS1 knockdown also increased AFAP1 protein expression. Proteomic and bioinformatics analyses suggested that AFAP1-AS1 affected the expression of several small GTPase family members and molecules in the actin cytokeratin signaling pathway. AFAP1-AS1 promoted cancer cell metastasis via regulation of actin filament integrity. AFAP1-AS1 might be a potential novel marker that can predict cancer patient prognosis and as a potential therapeutic target for NPC.

MMP13 Regulates Aggressiveness of Pediatric Multiple Myeloma Through VEGF-C

Background/Aims: Even though the blood and lymphatic vascular systems are both involved in the occurrence of cancer metastases, it is believed that lymphatic system is primarily responsible for the initial metastasis. Nevertheless, the molecular mechanisms underlying lymphangiogenesis of multiple myeloma (MM), especially in pediatric period, have not been clarified. Methods: Here we studied vascular endothelial growth factor C (VEGF-C) and matrix metalloproteinase 13 (MMP13) in pediatric MM patients. We overexpressed or inhibited VEGF-C in MM cells to study their effects on MMP13, and vice versa. A specific inhibitor for PI3k/Akt signaling pathway was used to examine the role of PI3k/Akt signaling in this regulatory axis. Results: Both VEGF-C and MMP13 significantly upregulated in MM with lymph-node metastases. A strong correlation between VEGF-C and MMP13 were detected in MM specimen. Using a human MM line 8226, we found that VEGF-C was regulated by MMP13 in MM cells, but not vice versa. Moreover, a specific PI3k/Akt inhibitor significantly abolished the effect of MMP13 on VEGF-C activation. Conclusion: Since VEGF-C is a well-known growth factor for lymphatic vessels, our data suggest that MMP13 may activate VEGF-C to promote cancer cell metastasis through lymphatic vascular systems in pediatric MM.

Aberrant expression of B7-H3 in gastric adenocarcinoma promotes cancer cell metastasis.

B7-H3 belongs to the B7 superfamily, a group of molecules that costimulate or downmodulate T cell responses. Although it has been shown that B7-H3 can inhibit T cell responses, several studies, most of them performed in murine systems, found B7-H3 to act in a co-stimulatory manner. In addition, B7-H3 is also expressed in various human cancers and is correlated with the poor outcome of cancer patients. The functional role of B7-H3 in cancer is still controversially discussed. In the present study, we compared B7-H3 expression in normal gastric tissues and gastric cancer tissue specimens and determined the effects of low B7-H3 expression on the human gastric cancer cell line SGC-7901 by using RNAi. B7-H3 expression in gastric specimens was determined by tissue qPCR and immunohistochemisty. A SGC-7901 cell line with low B7-H3 expression was established by lentiviral-mediated RNA interference to investigate the effect of B7-H3 on cancer cell migration and invasion invitro. By establishing an orthotopic transplantation gastric cancer mouse model, the effect of B7-H3 on cell migration and invasion was studied invivo. B7-H3 expression was significantly higher in the gastric cancer group than that in the normal gaster group. B7-H3 knockdown by RNA interference decreased cell migration and Transwell invasion up to 50% invitro. In the orthotopic transplantation gastric cancer mouse model, the effect of inhibiting metastasis by knockdown of B7-H3 was assessed in terms of the average postmortem abdominal visceral metastatic tumor weight. The results revealed that inhibition of B7-H3 expression reduced gastric cancer metastasis invivo. In conclusion, B7-H3 is aberrantly expressed in gastric cancer. In addition to modulating tumor immunity, B7-H3 may have a novel role in regulating SGC-7901 cell metastasis.

Modulation of Angiogenesis by Tumor Associated Macrophages in the Tumor Microenvironment

Macrophages are important cells in wound healing, providing aids for tissue cell growth, tissue matrix remodeling and angiogenesis. Solid tumor comprises not only tumor cells, but also tissue matrix and many stromal cells such as fibroblasts and macrophages. Tumor associated macrophages (TAMs) promote cancer metastasis through several mechanisms including tumor angiogenesis, tumor growth and cell migration and invasion. Complex paracrine signaling networks exist between TAMs and cancer cells to activate each other. The colony stimulating factor 1/epidermal growth factor paracrine loop is well known of breast cancer cell invasion. TAMs derived protease, such as matrix metalloproteinases, urokinase-type plasminogen activator, and cathespin B can promote cancer cell metastasis. By interacting with cancer cells, TAMs can be induced to express more cytokines and tissue matrixdegrading enzymes, such as matrix metalloproteinases, plasminogen activators and cathepsin B, that are either direct angiogenic factors or tissue matrix modulators responsible for promoting tumor angiogenesis. With evidence indicating TAMs tumorpromoting roles, many investigations have been undertaken to study the potential of using TAMs as the therapeutic target while some conflicting investigations have demonstrated their role in anti-tumor activity. More detailed mechanisms regarding the interaction between TAMs and tumor still need to be explored, and a thorough understanding of this interaction will provide some helpful conceptual suggestions for future cancer therapy. This mini review will summarize information about the role of TAMs on modulating angiogenesis in the inflammatory micro-environment of solid tumors and discuss the potential targets for future therapeutic approaches.

Phosphatase of regenerating liver-3 promotes colon cancer cells metastasis through inducing the secretion of interleukin-6 by tumor associated macrophages

Objective To investigate the mechanisms of phosphatase of regenerating Liver-3 (PRL-3) which promotes colon cancer cells (CRCs) metastasis through tumor associated macrophages (TAMs).Methods TAMs were cocuhured with Lovo-P cells.Real-time quantitative polymerase chain reaction (Real-time PCR) was used to screen the elevated mRNA of cytokines of the TAMs,and western blotting was used to examine the protein levels of the elevated cytokines.Immunofluorescence was used to examine the related TAMs in the sections of colon cancer patients.Kaplan-Meier was used to analysis the survival curves of the patients.Results Real-time PCR showed that the interleukin (IL)-6 mRNA of TAMs was significantly elevated (8.3 ± 2.2 fold higher),western blotting showed that the level of IL-6 elevated about 180％.After IL-6 antibody (5 mg/L and 10 mg/L) was added to the coculture medium,the invasion of Lovo-P cells was decreased significantly (220 ± 13 vs.132 ± 12 vs.83 ±7).Immunofluorescence showed that the location of TAMs was coincided with IL-6 fluorescence,and the IL-6 positive TAMs amounts of stage I patients are less than the stage Ⅳ patients (24 ±4 vs.56 ±9).A Kaplan-Meier survival curve demonstrated that patients with a high IL-6 positive TAMs counts (＞20) survive significantly shorter than those with low IL-6 positive TAMs counts (＜20) (27.3 m vs.12.2 m).Conclusion PRL-3 could induce TAMs secreting IL-6 and promotes CRCs metastasis,and influence the prognosis and survive of the patients. Key words: Phosphatase of regenerating liver-3 ; Tumor associated macrophages; Interleukin-6; Colon cancer

Effect of fas signaling on regulation of miR-23a-3p, miR-92a-3p, miR-138-5p, and miR-155-5p in gastric cancer cells.

e15077 Background: The Fas signaling pathway has been shown to promote cancer cell metastasis and motility through the epithelial-mesenchymal transition (EMT) in gastric cancer. Recent studies repo...

Clearing the way for cancer cells

Endothelial focal adhesion kinase helps tumor cells enter the bloodstream.

Long non-coding RNA HOTAIR, a driver of malignancy, predicts negative prognosis and exhibits oncogenic activity in oesophageal squamous cell carcinoma

Background:HOX transcript antisense RNA (HOTAIR), which is expressed from the homebox C gene (HOXC) locus, is capable of reprogramming chromatin organisation and promoting cancer cell metastasis and can simultaneously bind the polycomb repressive complex 2, which enhances H3K27 trimethylation, and the LSD1-CoREST-REST complex, which is critical for H3K4 demethylation. Clinically, the overexpression of HOTAIR is a powerful predictor of the tumour progression and overall survival in patients with diverse cancers. The relationship between HOTAIR and oesophageal squamous cell carcinoma (ESCC), however, remains unclear. We investigated the role of HOTAIR in the pathogenesis of ESCC.Methods:We used quantitative real-time PCR to determine the level of HOTAIR in ESCC cell lines and 100 ESCC samples from patients; 56 adjacent non-neoplastic tissues were used as controls. We measured the effect of HOTAIR knockdown and overexpression in ESCC cell lines using colony formation assays, anchorage-independent growth assays, the CCK-8 assay, transwell migration and invasion assays, and Annexin V-binding assays. We analysed the growth of ESCC xenograft tumours in nude mice. Changes in the gene expression and methylation levels in ESCC cell lines were analysed using gene expression microarrays and the Infinium HumanMethylation450K BeadChip assay, respectively.Results:The levels of HOTAIR were increased in ESCC cell lines and patient samples compared with the controls; the expression levels correlated with the disease stage and survival time. The knockdown of HOTAIR in the KYSE510 and KYSE180 ESCC cell lines using small hairpin RNAs (shRNAs) reduced the ability of the cells to form foci, migrate, and invade the extracellular matrix in culture, altered cell cycle progression, and increased the sensitivity of the cells to apoptosis. The HOTAIR knockdown reduced cancer cell metastasis in vivo, and the tumours formed by HOTAIR-silenced ESCC cells were smaller, both in size and weight, than the tumours and metastases formed by the shRNA vector control cells in a mouse xenograft model. The results of the gene microarray study showed that HOTAIR reprogrammed the gene expression profile of ESCC cells, and the gene ontology analysis revealed an enrichment in genes that are important for tumorigenesis, such as genes involved in cell migration and the regulation of the cell cycle. Comparing the gene expression profiles and DNA methylation analysis between the KYSE180 and KYSE180_HOTAIR cells revealed that only a small proportion of the methylation changes were correlated with gene expression changes.Conclusion:HOX transcript antisense RNA is upregulated in ESCC cell lines and patient samples, and promotes ESCC cell proliferation and tumour metastasis in mice. The knockdown of HOTAIR resulted in significant changes in gene expression, and data analysis suggested that HOTAIR-mediated gene regulation has a critical role in ESCC progression and is a novel epigenetic molecular target for treating ESCC patients.

Platelet-Derived Nucleotides Promote Tumor-Cell Transendothelial Migration and Metastasis via P2Y2 Receptor

Tumor cells can activate platelets, which in turn facilitate tumor cell survival and dissemination. The exact mechanisms by which platelets promote metastasis have remained unclear. Here, we show that adenine nucleotides released from tumor cell-activated platelets induce opening of the endothelial barrier to allow transendothelial migration of tumor cells and thereby promote cancer cell extravasation. We identified the endothelial P2Y2 receptor, which is activated by ATP, as the primary mediator of this effect. Mice deficient in P2Y2 or lacking ATP secretion from platelets show strongly reduced tumor cell metastasis. These findings demonstrate a mechanism by which platelets promote cancer cell metastasis and suggest the P2Y2 receptor and its endothelial downstream signaling mechanisms as a target for antimetastatic therapies.

Abstract 4588: Identification of CDCP1 as a HIF-2α target gene involved in the regulation of cancer cell migration and metastasis.

Abstract CUB domain-containing protein 1 (CDCP1) is a transmembrane protein that is highly expressed in stem cells and frequently overexpressed and tyrosine phosphorylated in cancer. CDCP1 promotes cancer cell metastasis. However, the mechanisms that regulate CDCP1 are not well defined. Studies from our laboratory revealed a biochemical pathway by which CDCP1 participates in the activation of Src-family kinase (SFK) members and the coupling of SFK-activation to the phosphorylation and regulation of protein kinase C-delta (PKC-δ). Here we show that hypoxia induces CDCP1 expression and tyrosine phosphorylation in a HIF-2α, but not HIF-1α, dependent fashion. shRNA knockdown of CDCP1 impairs cancer cell migration under hypoxic conditions, while overexpression of HIF-2α promotes the growth of tumor xenografts in association with enhanced CDCP1 expression and tyrosine phosphorylation, as well as, significantly promotes lung metastases in NOD/SCID mice. To investigate the relationship between HIF-2α and CDCP1 expression, we performed a correlation analysis in the largest up-to-date collection (Sanger Cell Line Project) of cancer cell line microarray data (n=732). We found a dramatic concordance in the expression of HIF-2α and CDCP1 (Pearson's correlation, P &amp;lt;1x10-20), indicating that cancers with high HIF-2α expression tend to have high levels of CDCP1 expression. We next asked whether other known HIF-2α target genes also correlate in this expression analysis. Remarkably, MET and EGFR, which are hypoxia regulated and known HIF-2α target genes, also displayed a strong correlation with HIF-2α and CDCP1 expression. Immunohistochemistry analysis of tissue microarray samples from tumors of patients with clear cell renal cell carcinoma (ccRCC) shows that increased CDCP1 expression correlates with decreased overall survival. Interestingly, high-grade ccRCCs (G3, G4) expressed significantly higher (P = 0.03, t-test) levels of CDCP1 protein compared to lower grade tumors (G1, G2), suggesting that CDCP1 expression increases progressively with higher ccRCC tumor grade. Furthermore, hypoxia activates Src signaling and the Src inhibitor (Dasatinib) prevents the hypoxia-induced phosphorylation of CDCP1. Thereby, reinforcing that CDCP1 is an SFK-associated receptor, which promotes migration and metastasis and suggests that hypoxia-induced CDCP1 signaling may further stimulate a more aggressive cancer phenotype. Together, these data support a critical role for CDCP1 as a unique HIF-2α target gene involved in the regulation of cancer metastasis, and suggest that therapeutic approaches targeting CDCP1, such as monoclonal antibodies, could be beneficial in the treatment of metastatic cancers. Supported by NIH grant 5R01GM056203-15 to L.C.C and Dana Farber/Harvard Cancer Center Career Development Award to B.M.E. Citation Format: Brooke M. Emerling, Cyril Benes, Eric Bell, George Poulogiannis, Kevin Courtney, Hui Lui, Rayman Choo-Wing, Gary Bellinger, Stephen Soltoff, Lewis Cantley. Identification of CDCP1 as a HIF-2α target gene involved in the regulation of cancer cell migration and metastasis. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 4588. doi:10.1158/1538-7445.AM2013-4588

Thioredoxin-Like Protein 2 Is Overexpressed in Colon Cancer and Promotes Cancer Cell Metastasis by Interaction with Ran

Our previous work identified thioredoxin-like protein 2 (Txl-2) as the target of the monoclonal antibody MC3 associated with colon cancer, but its underlying mechanisms remain poorly understood. Txl-2, a novel thioredoxin (Trx) and nucleoside diphosphate kinase family member, is alternatively spliced and gives rise to three different Txl-2 isoforms. In this study, Txl-2 expression in colon cancer, differential functions for Txl-2 isoforms in cell invasion and metastasis, and the downstream signaling were investigated. Txl-2 expression was elevated in colon cancer tissues compared to normal colonic tissues, with a high correlation between the histological grade and prognosis. Knockdown of Txl-2 expression significantly inhibited cancer cell motility, and the invasive and metastatic abilities of colon cancer cells. Interestingly, Txl-2 isoforms showed differential effects on cancer cell invasion and metastasis. Cell invasion and metastasis were significantly promoted by Txl-2b but inhibited by Txl-2c, while no obvious effect was observed for Txl-2a. Furthermore, a direct interaction was identified between Txl-2b and Ran, a Ras-related protein, by yeast two-hybrid assay and coimmunoprecipitation. PI3K pathway was found to be a major pathway mediating Txl-2b induced tumor invasion and metastasis. The current study provides a novel biomarker and target molecule for the diagnosis and treatment of colon cancer and provides a novel paradigm to understand how alternative splicing functions in human cancer. Our findings demonstrate an elevated Txl-2 expression in colon cancer and that Txl-2b promotes cell invasion and metastasis through interaction with Ran and PI3K signaling pathway.

Identification of CDCP1 as a hypoxia-inducible factor 2α (HIF-2α) target gene that is associated with survival in clear cell renal cell carcinoma patients

CUB domain-containing protein 1 (CDCP1) is a transmembrane protein that is highly expressed in stem cells and frequently overexpressed and tyrosine-phosphorylated in cancer. CDCP1 promotes cancer cell metastasis. However, the mechanisms that regulate CDCP1 are not well-defined. Here we show that hypoxia induces CDCP1 expression and tyrosine phosphorylation in hypoxia-inducible factor (HIF)-2α-, but not HIF-1α-, dependent fashion. shRNA knockdown of CDCP1 impairs cancer cell migration under hypoxic conditions, whereas overexpression of HIF-2α promotes the growth of tumor xenografts in association with enhanced CDCP1 expression and tyrosine phosphorylation. Immunohistochemistry analysis of tissue microarray samples from tumors of patients with clear cell renal cell carcinoma shows that increased CDCP1 expression correlates with decreased overall survival. Together, these data support a critical role for CDCP1 as a unique HIF-2α target gene involved in the regulation of cancer metastasis, and suggest that CDCP1 is a biomarker and potential therapeutic target for metastatic cancers.