Yi-Hua Lai

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.

The HLJ1-targeting drug screening identified Chinese herb andrographolide that can suppress tumour growth and invasion in non-small-cell lung cancer.

HLJ1 is a novel tumour suppressor and is a potential druggable target for non-small-cell lung cancer (NSCLC). In this report, using a promoter-containing enhancer region as the HLJ1-targeting drug-screening platform, we identified several herbal compounds from a Chinese herbal bank with the capacity to enhance HLJ1 promoter activity and suppress tumour growth and invasion of NSCLC. Among the herbal drugs identified, the andrographolide (from Andrographis paniculata [Burm. f.] Nees.) most significantly induced HLJ1 expression and suppressed tumorigenesis both in vitro and in vivo. The andrographolide upregulates HLJ1 via JunB activation, which modulates AP-2α binding at the MMP-2 promoter and represses the expression of MMP-2. In addition, silencing of HLJ1 partially reverses the inhibition of cancer-cell invasion by andrographolide. Microarray transcriptomic analysis was performed to comprehensively depict the andrographolide-regulated signalling pathways. We showed that andrographolide can affect 939 genes (analysis of variance, false discovery rate < 0.05) that are dominantly involved in the cell cycle, apoptosis and adhesion-related biological signalling, including mitogen-activated protein kinase, focal adhesion and tight junction pathways, indicating the diverse effects of andrographolide on anticancer invasion and proliferation. In conclusion, the HLJ1-targeting drug-screening platform is useful for screening of novel anticancer compounds. Using this platform, we identified andrographolide is a promising new anticancer agent that could suppress tumour growth and invasion in NSCLC.

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.

Spermine Attenuates the Action of the DNA Intercalator, Actinomycin D, on DNA Binding and the Inhibition of Transcription and DNA Replication

The anticancer activity of DNA intercalators is related to their ability to intercalate into the DNA duplex with high affinity, thereby interfering with DNA replication and transcription. Polyamines (spermine in particular) are almost exclusively bound to nucleic acids and are involved in many cellular processes that require nucleic acids. Until now, the effects of polyamines on DNA intercalator activities have remained unclear because intercalation is the most important mechanism employed by DNA-binding drugs. Herein, using actinomycin D (ACTD) as a model, we have attempted to elucidate the effects of spermine on the action of ACTD, including its DNA-binding ability, RNA and DNA polymerase interference, and its role in the transcription and replication inhibition of ACTD within cells. We found that spermine interfered with the binding and stabilization of ACTD to DNA. The presence of increasing concentrations of spermine enhanced the transcriptional and replication activities of RNA and DNA polymerases, respectively, in vitro treated with ActD. Moreover, a decrease in intracellular polyamine concentrations stimulated by methylglyoxal-bis(guanylhydrazone) (MGBG) enhanced the ACTD-induced inhibition of c-myc transcription and DNA replication in several cancer cell lines. The results indicated that spermine attenuates ACTD binding to DNA and its inhibition of transcription and DNA replication both in vitro and within cells. Finally, a synergistic antiproliferative effect of MGBG and ACTD was observed in a cell viability assay. Our findings will be of significant relevance to future developments in combination with cancer therapy by enhancing the anticancer activity of DNA interactors through polyamine depletion.

Multiple target drug cocktail design for attacking the core network markers of four cancers using ligand-based and structure-based virtual screening methods

BackgroundComputer-aided drug design has a long history of being applied to discover new molecules to treat various cancers, but it has always been focused on single targets. The development of systems biology has let scientists reveal more hidden mechanisms of cancers, but attempts to apply systems biology to cancer therapies remain at preliminary stages. Our lab has successfully developed various systems biology models for several cancers. Based on these achievements, we present the first attempt to combine multiple-target therapy with systems biology.MethodsIn our previous study, we identified 28 significant proteins--i.e., common core network markers--of four types of cancers as house-keeping proteins of these cancers. In this study, we ranked these proteins by summing their carcinogenesis relevance values (CRVs) across the four cancers, and then performed docking and pharmacophore modeling to do virtual screening on the NCI database for anti-cancer drugs. We also performed pathway analysis on these proteins using Panther and MetaCore to reveal more mechanisms of these cancer house-keeping proteins.ResultsWe designed several approaches to discover targets for multiple-target cocktail therapies. In the first one, we identified the top 20 drugs for each of the 28 cancer house-keeping proteins, and analyzed the docking pose to further understand the interaction mechanisms of these drugs. After screening for duplicates, we found that 13 of these drugs could target 11 proteins simultaneously. In the second approach, we chose the top 5 proteins with the highest summed CRVs and used them as the drug targets. We built a pharmacophore and applied it to do virtual screening against the Life-Chemical library for anti-cancer drugs. Based on these results, wet-lab bio-scientists could freely investigate combinations of these drugs for multiple-target therapy for cancers, in contrast to the traditional single target therapy.ConclusionsCombination of systems biology with computer-aided drug design could help us develop novel drug cocktails with multiple targets. We believe this will enhance the efficiency of therapeutic practice and lead to new directions for cancer therapy.

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.

AC-93253 iodide, a novel Src inhibitor, suppresses NSCLC progression by modulating multiple Src-related signaling pathways

BackgroundThe tyrosine kinase Src is involved in the progression of many cancers. Moreover, inhibiting Src activity has been shown to obstruct several signaling pathways regulated by the EGFR. Thus, Src is a valuable target molecule in drug development. The purpose of this study was to identify compounds that directly or indirectly modulate Src to suppress lung cancer cell growth and motility and to investigate the molecular mechanisms underlying the effects of these compounds.MethodsHuman non-small cell lung cancer (NSCLC) cell lines (PC9, PC9/gef, A549, and H1975) with different EGFR statuses were tested by cytotoxicity and proliferation assays after AC-93253 iodide treatment. Src and Src-related protein expression in AC-93253 iodide-treated PC9, PC9/gef, and A549 cells were assessed by western blotting. The effects of AC-93253 iodide on cancer cell colony formation, invasion, and migration were assessed in PC9 and PC9/gef cells. The synergistic effects of gefitinib and AC-93253 iodide were evaluated by combination index (CI)-isobologram analysis in gefitinib-resistant cell lines. The efficacy of AC-93253 iodide in vivo was determined using nude mice treated with either the compound or the vehicle.ResultsAmong the compounds, AC-93253 iodide exhibited the most potent dose-independent inhibitory effects on the activity of Src as well as on that of the Src-related proteins EGFR, STAT3, and FAK. Furthermore, AC-93253 iodide significantly suppressed cancer cell proliferation, colony formation, invasion, and migration in vitro and tumor growth in vivo. AC-93253 iodide sensitized tumor cells to gefitinib treatment regardless of whether the cells were gefitinib-sensitive (PC9) or resistant (H1975 and PC9/gef), indicating that it may exert synergistic effects when used in combination with established therapeutic agents. Our findings also suggested that the inhibitory effects of AC-93253 iodide on lung cancer progression may be attributable to its ability to modulate multiple proteins, including Src, PI3K, JNK, Paxillin, p130cas, MEK, ERK, and EGFR.ConclusionsOur data suggest that AC-93253 iodide inhibits NSCLC cell growth and motility by regulating multiple Src-related pathways. Our findings may facilitate the development of therapeutic strategies and anti-tumor drugs that may be useful for treating lung cancer in the future.

Abstract 77: Study of the effect of MAPRE2 on human lung adenocarcinoma cell migration and invasion

Lung cancer is the most malignant disease which makes lots of people dead worldwide. More and more evidences showed that cancers might arise from chromosome alteration, including amplification or deletion. Our previous study integrating microarray-based comparative genomic hybridization and affymetrix gene expression profiles identified a potential candidate gene, MAPRE2, in a lung cancer cell line model with different invasion capability. MAPRE2 (Microtubule-associated protein RP/EB family member 2) is usually located on microtubule and interactes with tumor suppress gene APC (adenomatous polyposis coli). MAPRE2 might be involved in microtubule polymerization, cell migration and tumorigenesis of colorectal cancers, but its function is unclear. The purpose of this study is to investigate the effects of MAPRE2 on cancer cell function. The results of real-time PCR and western blotting showed that DNA copy number, RNA and protein level of MAPRE2 were higher in low invasive lung cancer cells than in highly invasive cells. Immunofluorescence assay indicated that the distribution of MAPRE2 protein was predominant in cytoplasm. Furthermore, overexpression of MAPRE2 could inhibit cancer cell proliferation, anchorage- dependent and -independent growth, cell motility, invasion ability in vitro and tumor growth and metastasis in vivo. On the contrary, silencing MAPRE2 enhanced lung cancer cell proliferation and invasion ability. Consider the whole map of MAPRE2-regulated signalling, transcriptomic analysis was performed and the results showed that MAPRE2 could affect 1039 genes (ANOVA, FDR 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 77. doi:1538-7445.AM2012-77

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

Abstract 2360: Dimethyl sulfoxide induces upregulation of tumor suppressor HLJ1 through activator protein-1 activation in human lung adenocarcinoma CL1-5 cells

Dimethyl sulfoxide (DMSO) is an amphipathic molecule and has a diversity of antitumor activities. Previous studies demonstrated that DMSO could modulate AP-1 activity and lead to cell cycle arrest at G1 phase. HLJ1 is a newly identified tumor and invasion suppressor that inhibits tumorigenesis and cancer metastasis. Its transcriptional activity is also regulated by transcription factor AP-1. However, the effect of DMSO on HLJ1 is still unknown. In this study, low-HLJ1 expressing highly invasive CL1-5 lung adenocarcinoma cells were subjected to DMSO treatment. We found that DMSO can significantly inhibit cancer cell invasion and migration capabilities through up-regulation of HLJ1 in a concentration-dependent manner. In addition, knockdown of HLJ1 expression by siRNA was able to block the effects of DMSO-induction. The HLJ1 promoter and enhancer reporter assay revealed that DMSO transcriptionally upregulates HLJ1 expression through an AP-1 site within the HLJ1 enhancer. Furthermore, AP-1 subfamily members, JunD and JunB, were significantly upregulated by DMSO in a concentration-dependent manner. In conclusion, our results suggest that DMSO could be an important stimulator of the tumor suppressor protein, HLJ1, through AP-1 activation in highly invasive lung adenocarcinoma CL1-5 cells. Our findings provide some important information for further investigations to develop new drugs such as DMSO-derived analogues which may inhibit cancer invasion and progression by targeting HLJ1. 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 2360. doi:10.1158/1538-7445.AM2011-2360