Jau Chen Lin

MicroRNA-135b promotes lung cancer metastasis by regulating multiple targets in the Hippo pathway and LZTS1

Dysregulation of microRNAs has a critical role in cancer progression. Here we identify an intronic microRNA, miR-135b that is upregulated in highly invasive non-small-cell lung cancer cells. Expression of miR-135b enhances cancer cell invasive and migratory abilities in vitro and promotes cancer metastasis in vivo, while specific inhibition of miR-135b by a miR-135b-specific molecular sponge and antagomirs suppresses cancer cell invasion, orthotopic lung tumour growth and metastasis in a mouse model. miR-135b targets multiple key components in the Hippo pathway, including LATS2, β-TrCP and NDR2, as well as LZTS1. Expression of miR-135b, LZTS1, LATS2 and nuclear TAZ predicts poor outcomes of non-small-cell lung cancer. We find that miR-135b is dually regulated by DNA demethylation and nuclear factor-kappaB signalling, implying that abnormal expression of miR-135b in cancer may result from inflammatory and epigenetic modulations. We conclude that miR-135b is an oncogenic microRNA and a potential therapeutic target for non-small-cell lung cancer.

SCUBE3 is an endogenous TGF-β receptor ligand and regulates the epithelial-mesenchymal transition in lung cancer

Signal peptide-CUB-EGF-like domain-containing protein 3 (SCUBE3) is a secreted glycoprotein that is overexpressed in lung cancer tumor tissues and is correlated with the invasive ability in a lung cancer cell line model. These observations suggest that SCUBE3 may have a role in lung cancer progression. By exogenous SCUBE3 treatment or knockdown of SCUBE3 expression, we found that SCUBE3 could promote lung cancer cell mobility and invasiveness. Knockdown of SCUBE3 expression also suppressed tumorigenesis and cancer metastasis in vivo. The secreted SCUBE3 proteins were cleaved by gelatinases (matrix metalloprotease-2 (MMP-2) and MMP-9) in media to release two major fragments: the N-terminal epidermal growth factor-like repeats and the C-terminal complement proteins C1r/C1s, Uegf and Bmp1 (CUB) domain. Both the purified SCUBE3 protein and the C-terminal CUB domain fragment, bound to transforming growth factor-β (TGF-β) type II receptor through the C-terminal CUB domain, activated TGF-β signaling and triggered the epithelial-mesenchymal transition (EMT). This process includes the induction of Smad2/3 phosphorylation, the increase of Smad2/3 transcriptional activity and the upregulation of the expression of target genes involved in EMT and cancer progression (such as TGF-β1, MMP-2, MMP-9, plasminogen activator inhibitor type-1, vascular endothelial growth factor, Snail and Slug), thus promoting cancer cell mobility and invasion. In conclusion, in lung cancer cells, SCUBE3 could serve as an endogenous autocrine and paracrine ligand of TGF-β type II receptor, which could regulate TGF-β receptor signaling and modulate EMT and cancer progression.

TROP2 is epigenetically inactivated and modulates IGF‐1R signalling in lung adenocarcinoma

Trop‐2, a cell surface glycoprotein, contains both extracellular epidermal growth factor‐like and thyroglobulin type‐1 repeat domains. Low TROP2 expression was observed in lung adenocarcinoma tissues as compared with their normal counterparts. The lack of expression could be due to either the loss of heterozygosity (LOH) or hypermethylation of the CpG island DNA of TROP2 upstream promoter region as confirmed by bisulphite sequencing and methylation‐specific (MS) polymerase chain reaction (PCR). 5‐Aza‐2′‐deoxycytidine treatment on lung cancer cell (CL) lines, CL1‐5 and A549, reversed the hypermethylation status and elevated both TROP2 mRNA and protein expression levels. Enforced expression of TROP2 in the lung CL line H1299 reduced AKT as well as ERK activation and suppressed cell proliferation and colony formation. Conversely, silencing TROP2 with shRNA transfection in the less efficiently tumour‐forming cell line H322M enhanced AKT activation and increased tumour growth. Trop‐2 could attenuate IGF‐1R signalling‐mediated AKT/β‐catenin and ERK activation through a direct binding of IGF1. In conclusion, inactivation of TROP2 due to LOH or by DNA methylation may play an important role in lung cancer tumourigenicity through losing its suppressive effect on IGF‐1R signalling and tumour growth.

Antitumor agents 288: design, synthesis, SAR, and biological studies of novel heteroatom-incorporated antofine and cryptopleurine analogues as potent and selective antitumor agents.

Novel heteroatom-incorporated antofine and cryptopleurine analogues were designed, synthesized, and tested against a panel of five cancer cell lines. Two new S-13-oxo analogues (11 and 16) exhibited potent cell growth inhibition in vitro (GI(50): 9 nM and 20 nM). Interestingly, both compounds displayed improved selectivity among different cancer cell lines, in contrast to the natural products antofine and cryptopleurine. Mechanism of action (MOA) studies suggested that R-antofine promotes dysregulation of DNA replication during early S phase, while no similar effects were observed for 11 and 15 on corresponding replication initiation complexes. Compound 11 also showed greatly reduced cytotoxicity against normal cells and moderate antitumor activity against HT-29 human colorectal adenocarcinoma xenograft in mice without overt toxicity.

Modulation of the expression of the invasion-suppressor CRMP-1 by cyclooxygenase-2 inhibition via reciprocal regulation of Sp1 and C/EBPα

Collapsin response mediator protein-1 (CRMP-1) controls neural development and axonal growth but also acts as a cancer invasion suppressor. In this study, we investigated the transcriptional regulation of CRMP-1 expression. Using a serial deletion strategy, we identified a basal promoter region between nucleotides -100 and -180 in the 5′ flanking region of CRMP-1 (nucleotides -1,920 to +50) that contains multiple putative Sp1 and C/EBPα sites. Site-directed mutagenesis and deletion analysis revealed that the two C/EBPα sites, from nucleotides -122 to -133 and from nucleotides -101 to -113, are the most important regulatory elements. Gel-shift and antibody supershift assays showed that Sp1 protein was also present at this C/EBPα site, which overlaps with a Sp1 site. Overexpression of Sp1 decreased CRMP-1 promoter activity and protein expression, whereas overexpression of C/EBPα produced the opposite effect. Chromatin immunoprecipitation assays confirmed that Sp1 and C/EBPα compete for binding at the overlapping C/EBPα and Sp1 sites and reciprocally regulate CRMP-1 expression. Overexpression of cyclooxygenase-2 (COX-2) decreased CRMP-1 mRNA and protein expression. Conversely, the COX-2 inhibitor, celecoxib, induced a dose-dependent increase in CRMP-1 expression. COX-2 inhibition also decreased Sp1-DNA complex formation and inhibited cell invasion. We conclude that transcription of the invasion suppressor, CRMP-1, is reciprocally regulated at the promoter region by C/EBPα and Sp1. COX-2 inhibitors increase CRMP-1 expression by inhibiting Sp1-DNA complex formation and enhancing DNA binding of C/EBPα at the promoter. [Mol Cancer Ther 2008;7(6):1365–75]

The antitumor agent PBT-1 directly targets HSP90 and hnRNP A2/B1 and inhibits lung adenocarcinoma growth and metastasis

Natural products are the major sources of currently available anticancer drugs. We recently reported that phenanthrene-based tylophorine derivative-1 (PBT-1) may be a potential antitumor agent for lung adenocarcinoma. We therefore examined the direct targets of PBT-1 and their effects in inhibiting lung adenocarcinoma. We found that PBT-1 reduced the level of Slug and inhibits the migration, invasion, and filopodia formation of lung adenocarcinoma CL1-5 cells in vitro. In addition, PBT-1 displayed in vivo antitumor and antimetastasis activities against subcutaneous and orthotopic xenografts of CL1-5 cells in nude mice. Chemical proteomics showed that heat shock protein 90 (HSP90) and heterogeneous nuclear ribonucleoproteins A2/B1 (hnRNP A2/B1) bound PBT-1 in CL1-5 cells. Inhibition of HSP90 and hnRNP A2/B1 reduced the activation of AKT and Slug expression. Taken together, these findings suggest that PBT-1 binds to HSP90 and/or hnRNP A2/B1 and initiates antitumor activities by affecting Slug- and AKT-mediated metastasis and tumorigenesis.

MODULATION OF MDR-1 GENE BY MIF AND GSTpi WITH DRUG RESISTANCE GENERATION IN HORMONE INDEPENDENT PROSTATE CANCER

The expression of MIF and GSTpi were upregulated in prostate cancer cells with mulitdrug resistant phenotype. The aim of this study is to determine the relationship between these genes and multidrug resistance (mdr-1) gene in acquired multidrug resistance of prostate cancer. The expression of MIF, GSTpi and gp-170 in multidrug resistant (MDR) subline or native cells were determined using flow cytometry and western blotting. The mRNA level of various genes was analyzed with RT-PCR method. The chemosensitivity of tumor cells and stable transfectants to paclitaxel was measured using MTT (tetrazolium bromide) assay. The protein levels of MIF, GSTpi and gp-170 increased in MDR sublines of prostate cancer when compared with their parental cells. The MIF and GSTpi stable transfectants expressed higher MIF and GSTpi protein levels than their parental cells in western blotting analysis, respectively. The expression of mdr-1 gene and the production of pg-170 were also increased in either MIF or GSTpi stable transfectants when compared with vector control by using RT-PCR and flow cytometric analysis. The MTT results demonstrated that the increased chemoresistance was correlated with the increased production of gp-170 protein in either MIF or GSTpi transfectants. The upregulation of MIF and GSTpi during the development of acquired drug resistance of hormone independent prostate cancer may simultaneously and partially modulate the activation of gp-170.

Abstract 3976: The role of a novel oncomiR, miR-135b, in lung cancer metastasis and clinical application

Proceedings: AACR 102nd Annual Meeting 2011‐‐ Apr 2‐6, 2011; Orlando, FL microRNA(miR) may function endogenous siRNA and regulate a diversity of cellular function through translational repression. Dysregulations of miR expression are involved in carcinogenesis and progression in various cancers. By combining the miR microarray and genomic DNA-methylation array, we identified an intronic miR, miR-135b, which is up-regulated in high invasive lung cancer cell CL1-5. The promoter region of miR-135b is highly de-methylated in high invasive cells and its expression in the less invasive lung cancer cells can be induced by demethylating agent 5’-aza-CdR treatment. Ectopically expression of miR-135b enhanced cell invasive and migratory ability in vitro as well as the orthotopic tumor growth and lung metastasis activity in vivo, whereas specific inhibition of miR-135b decreased tumor growth and metastatic activities. Using the bioinformatic prediction tools, we identified and confirmed that miR-135b could directly repress the expression of Lzts1 through 3’UTR seed-binding. Ectopically-expressed Lzts1 inhibited cell invasion and migration activity, implicating that miR-135b may promote lung cancer cell metastasis by down-regulating Lzts1. Moreover, high level of miR-135b and low level of Lzts1 expressions were associated with poor overall survival in lung cancer patients. We also showed that the miR-135b expression was regulated by NF-κB signaling-cascade and synergistically induced by co-treatment of 5’-aza-CdR and TNF-α, implying that the abnormal expression of miR-135b in cancers may result from inflammatory stimulation and epigenetic modulation. Our results support that miR-135b is an oncogenic miR that may contribute to lung cancer progression and metastasis. The miR-135b/Lzts1 pathway is a promising therapeutic target of lung cancer. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 3976. doi:10.1158/1538-7445.AM2011-3976