Sheng-Yi Lin

The location and translocation of ndh genes of chloroplast origin in the Orchidaceae family

The NAD(P)H dehydrogenase complex is encoded by 11 ndh genes in plant chloroplast (cp) genomes. However, ndh genes are truncated or deleted in some autotrophic Epidendroideae orchid cp genomes. To determine the evolutionary timing of the gene deletions and the genomic locations of the various ndh genes in orchids, the cp genomes of Vanilla planifolia, Paphiopedilum armeniacum, Paphiopedilum niveum, Cypripedium formosanum, Habenaria longidenticulata, Goodyera fumata and Masdevallia picturata were sequenced; these genomes represent Vanilloideae, Cypripedioideae, Orchidoideae and Epidendroideae subfamilies. Four orchid cp genome sequences were found to contain a complete set of ndh genes. In other genomes, ndh deletions did not correlate to known taxonomic or evolutionary relationships and deletions occurred independently after the orchid family split into different subfamilies. In orchids lacking cp encoded ndh genes, non cp localized ndh sequences were identified. In Erycina pusilla, at least 10 truncated ndh gene fragments were found transferred to the mitochondrial (mt) genome. The phenomenon of orchid ndh transfer to the mt genome existed in ndh-deleted orchids and also in ndh containing species.

Dimethyl sulfoxide promotes the multiple functions of the tumor suppressor HLJ1 through activator protein-1 activation in NSCLC cells.

Background Dimethyl sulfoxide (DMSO) is an amphipathic molecule that displays a diversity of antitumor activities. Previous studies have demonstrated that DMSO can modulate AP-1 activity and lead to cell cycle arrest at the G1 phase. HLJ1 is a newly identified tumor and invasion suppressor that inhibits tumorigenesis and cancer metastasis. Its transcriptional activity is regulated by the transcription factor AP-1. However, the effects of DMSO on HLJ1 are still unknown. In the present study, we investigate the antitumor effects of DMSO through HLJ1 induction and demonstrate the mechanisms involved. Methods and Findings Low-HLJ1-expressing highly invasive CL1–5 lung adenocarcinoma cells were treated with various concentrations of DMSO. We found that DMSO can significantly inhibit cancer cell invasion, migration, proliferation, and colony formation capabilities through upregulation of HLJ1 in a concentration-dependent manner, whereas ethanol has no effect. In addition, the HLJ1 promoter and enhancer reporter assay revealed that DMSO transcriptionally upregulates HLJ1 expression through an AP-1 site within the HLJ1 enhancer. The AP-1 subfamily members JunD and JunB were significantly upregulated by DMSO in a concentration-dependent manner. Furthermore, pretreatment with DMSO led to a significant increase in the percentage of UV-induced apoptotic cells. Conclusions Our results suggest that DMSO may be an important stimulator of the tumor suppressor protein HLJ1 through AP-1 activation in highly invasive lung adenocarcinoma cells. Targeted induction of HLJ1 represents a promising approach for cancer therapy, which also implied that DMSO may serve as a potential lead compound or coordinated ligand for the development of novel anticancer drugs.

Digoxin Suppresses Tumor Malignancy through Inhibiting Multiple Src-Related Signaling Pathways in Non-Small Cell Lung Cancer

Non-small cell lung cancer is the predominant type of lung cancer, resulting in high mortality worldwide. Digoxin, a cardiac glycoside, has recently been suggested to be a novel chemotherapeutic agent. Src is an oncogene that plays an important role in cancer progression and is therefore a potential target for cancer therapy. Here, we investigated whether digoxin could suppress lung cancer progression through the inhibition of Src activity. The effects of digoxin on lung cancer cell functions were investigated using colony formation, migration and invasion assays. Western blotting and qPCR assays were used to analyze the mRNA and protein expression levels of Src and its downstream proteins, and a cell viability assay was used to measure cellular cytotoxicity effects. The results of the cell function assays revealed that digoxin inhibited the proliferation, invasion, migration, and colony formation of A549 lung cancer cells. Similar effects of digoxin were also observed in other lung cancer cell lines. Furthermore, we found that digoxin significantly suppressed Src activity and its protein expression in a dose- and time-dependent manner as well as reduced EGFR and STAT3 activity. Our data suggest that digoxin is a potential anticancer agent that may suppress lung cancer progression through inhibiting Src and the activity of related proteins.

Tumor Suppressor HLJ1 Binds and Functionally Alters Nucleophosmin via Activating Enhancer Binding Protein 2α Complex Formation

HLJ1, a member of the heat shock protein 40 chaperone family, is a newly identified tumor suppressor that has been implicated in tumorigenesis and metastasis in non-small cell lung cancer. However, the mechanism of HLJ1 action is presently obscure. In this study, we report that HLJ1 specifically interacts with the nuclear protein nucleophosmin (NPM1), forming a multiprotein complex that alters the nucleolar distribution and oligomerization state of NPM1. Enforced accumulation of NPM1 oligomers by overexpression in weakly invasive but high HLJ1-expressing cells induced the activity of signal transducer and activator of transcription 3 (STAT3) and increased cellular migration, invasiveness, and colony formation. Furthermore, silencing HLJ1 accelerated NPM1 oligomerization, inhibited the activity of transcription corepressor activating enhancer binding protein 2alpha (AP-2alpha), and increased the activities of matrix metalloproteinase-2 (MMP-2) and STAT3. Our findings suggest that HLJ1 switches the role of NPM1, which can act as tumor suppressor or oncogene, by modulating the oligomerization of NPM1 via HLJ1-NPM1 heterodimer formation and recruiting AP-2alpha to the MMP-2 promoter.

HLJ1 is a novel caspase-3 substrate and its expression enhances UV-induced apoptosis in non-small cell lung carcinoma

Carcinogenesis is determined based on both cell proliferation and death rates. Recent studies demonstrate that heat shock proteins (HSPs) regulate apoptosis. HLJ1, a member of the DnaJ-like Hsp40 family, is a newly identified tumor suppressor protein closely related to relapse and survival in non-small cell lung cancer (NSCLC) patients. However, its role in apoptosis is currently unknown. In this study, NSCLC cell lines displaying varying HLJ1 expression levels were subjected to ultraviolet (UV) irradiation, followed by flow cytometry. Interestingly, the percentages of apoptotic cells in the seven cell lines examined were positively correlated with HLJ1 expression. Enforcing expression of HLJ1 in low-HLJ1 expressing highly invasive cells promoted UV-induced apoptosis through enhancing JNK and caspase-3 activation in NSCLC. Additionally, UV irradiation led to reduced levels of HLJ1 predominantly in apoptotic cells. The pan-caspase inhibitor, zVAD-fmk and caspase-3-specific inhibitor, DEVD-fmk, prevented UV-induced degradation of HLJ1 by the late stage of apoptosis. Further experiments revealed a non-typical caspase-3 cleavage site (MEID) at amino acid 125–128 of HLJ1. Our results collectively suggest that HLJ1 is a novel substrate of caspase-3 during the UV-induced apoptotic process.

Acidic stress facilitates tyrosine phosphorylation of HLJ1 to associate with actin cytoskeleton in lung cancer cells

Acidosis is a common stress in solid tumours and is also a major determinant of tumour growth, metabolism, and metastasis. During cellular stress, heat shock proteins play an important role in actin cytoskeleton stability. HLJ1, a member of the DnaJ-like heat shock protein 40, has been characterised as a tumour suppressor gene; however, the effect of acidic stress on HLJ1 is unknown. In this study, we found that the migration ability of human lung adenocarcinoma cells was significantly impaired following the increased protein level of HLJ1 under acidic culture conditions. However, HLJ1 transcriptional activity was no different in the normal and acidic culture medium. Incubation of the cells in an acidic extracellular pH (pHe 6.4) caused up-regulated tyrosine phosphorylation of HLJ1 within 2h. We further identified the sub-cellular distribution of tyrosine phospho-HLJ1 and its tyrosine-phosphorylated sites. Most importantly, acidic stress was observed to remarkably enhance the interaction between HLJ1 and β-actin, which was a tyrosine phosphorylation-dependent association. In conclusion, our results not only validate that HLJ1 is a tyrosine phosphoprotein, but also suggest that the increased level of tyrosine phospho-HLJ1 is crucial for binding with the actin cytoskeleton, especially in acidic pHe. We propose that acidic stress increases the association between HLJ1 and β-actin to modulate migration of human lung cancer cells.

Rhodomycin A, a novel Src-targeted compound, can suppress lung cancer cell progression via modulating Src-related pathways.

Src activation is involved in cancer progression and the interplay with EGFR. Inhibition of Src activity also represses the signalling pathways regulated by EGFR. Therefore, Src has been considered a target molecule for drug development. This study aimed to identify the compounds that target Src to suppress lung cancer tumourigenesis and metastasis and investigate their underlying molecular mechanisms. Using a molecular docking approach and the National Cancer Institute (NCI) compound dataset, eight candidate compounds were selected, and we evaluated their efficacy. Among them, rhodomycin A was the most efficient at reducing the activity and expression of Src in a dose-dependent manner, which was also the case for Src-associated proteins, including EGFR, STAT3, and FAK. Furthermore, rhodomycin A significantly suppressed cancer cell proliferation, migration, invasion, and clonogenicity in vitro and tumour growth in vivo. In addition, rhodomycin A rendered gefitinib-resistant lung adenocarcinoma cells more sensitive to gefitinib treatment, implying a synergistic effect of the combination therapy. Our data also reveal that the inhibitory effect of rhodomycin A on lung cancer progression may act through suppressing the Src-related multiple signalling pathways, including PI3K, JNK, Paxillin, and p130cas. These findings will assist the development of anti-tumour drugs to treat lung cancer.

Inferring condition-specific targets of human TF-TF complexes using ChIP-seq data

BackgroundTranscription factors (TFs) often interact with one another to form TF complexes that bind DNA and regulate gene expression. Many databases are created to describe known TF complexes identified by either mammalian two-hybrid experiments or data mining. Lately, a wealth of ChIP-seq data on human TFs under different experiment conditions are available, making it possible to investigate condition-specific (cell type and/or physiologic state) TF complexes and their target genes.ResultsHere, we developed a systematic pipeline to infer Condition-Specific Targets of human TF-TF complexes (called the CST pipeline) by integrating ChIP-seq data and TF motifs. In total, we predicted 2,392 TF complexes and 13,504 high-confidence or 127,994 low-confidence regulatory interactions amongst TF complexes and their target genes. We validated our predictions by (i) comparing predicted TF complexes to external TF complex databases, (ii) validating selected target genes of TF complexes using ChIP-qPCR and RT-PCR experiments, and (iii) analysing target genes of select TF complexes using gene ontology enrichment to demonstrate the accuracy of our work. Finally, the predicted results above were integrated and employed to construct a CST database.ConclusionsWe built up a methodology to construct the CST database, which contributes to the analysis of transcriptional regulation and the identification of novel TF-TF complex formation in a certain condition. This database also allows users to visualize condition-specific TF regulatory networks through a user-friendly web interface.

Abstract 3432: HLJ1 serves as an inhibitor of epithelial-mesenchymal transition by inactivating β-catenin signaling

Proceedings: AACR 103rd Annual Meeting 2012‐‐ Mar 31‐Apr 4, 2012; Chicago, IL HLJ1 (DnaJ-like heat shock protein), also known as DNAJB4, was classified as a tumor suppressor gene. The expression of HLJ1 inversely associates with invasive ability and can predict the clinical outcomes of non-small-cell lung cancer (NSCLC) patients. However, the role of HLJ1 in suppressing cancer metastasis is still unclear. Here, we identified HLJ1 as a novel inhibitor of epithelial-mesenchymal transition (EMT). Our functional assays in vitro and in vivo demonstrated that Knock-down of HLJ1 promotes invasion capabilities of lung cancer cells and causes liver macrometastasis; meanwhile, the crucial domain of HLJ1 in suppression of cancer invasion was also confirmed. We found that the HLJ1-overexpressing cells maintain the well-organized cell adhesion and polarity. Inversely, an increase in actin polymerization and the formation of actin stress fibers were observed in the HLJ1-silencing cells. HLJ1 down-regulates the transcriptional activities of slug promoter and facilitates E-cadherin transcription, leading to the inhibition of epithelial to mesenchymal transition. Further, we identified the Wnt/β-catenin signalling pathway in which HLJ1 involved by cDNA microarray and pathway analysis. The subcellular distribution of β-catenin is predominant in the nucleus and the tyrosine-phosphorylated levels of β-catenin are up-regulated in the HLJ1-silenced clones. Finally, we showed a decreased accumulation of β-catenin and an enhanced degradation of β-catenin in absence of HLJ1 expression. Taken together, our study reveals that HLJ1 has anti-metastatic activity by repressing β-catenin signaling and provides a molecular model for the development of new anticancer agents. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 3432. doi:1538-7445.AM2012-3432

Abstract 4183: Overexpression of PTPN2 promotes lung cancer cell proliferation through ERK activation

Lung cancer is the most common cause of cancer deaths in the world, and the incidence is increasing each year. Protein tyrosine phosphatases (PTPs) and their associated signaling pathways are crucial for the regulation of numerous cell functions including growth, motility, mitogenesis and metabolism. PTPN2, also known as TCPTP, is an intracellular protein tyrosine phosphatase, which is ubiquitously expressed. There are two splice variants of TCPTP in human cells, TC45 and TC48, which vary at their C-terminal ends. The TC48 isoform is present in the endoplasmic reticulum and also in the nuclear membrane. However, its role and function on human non-small cell lung cancers remain unknown. In this study, we induced ectopic expression of PTPN2 (TC48) in CL1-0 and H1299 cells to investigate its effect on cell migration, invasion, and colony formation. The interacting proteins of PTPN2 are identified by yeast two-hybrid assay. The results showed that PTPN2 inhibited lung cancer cell proliferation, anchorage-dependent and -independent growth, but not migration and invasion. Yeast two-hybrid assay revealed that PTPN2 interacted with CD74 (major histocompatibility complex class II invariant chain) and PRDX6 (Peroxiredoxin 6) which could promote cell proliferation in previous studies. We also found that overexpression of PTPN2 increased the phosphorylation of ERK. Moreover, activation of ERK was enhanced by co-expression of PTPN2 and CD74 or PRDX6. Taken together, we speculated that PTPN2 might modulate ERK activity through interaction with CD74 and PRDX6 and further promoted lung cancer cell proliferation. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 4183. doi:1538-7445.AM2012-4183