Molecular Signaling and Cancer Research Group
Glucocorticoids Mediate Induction of MicroRNA-708 to Suppress Ovarian Cancer Metastasis through Targeting Rap1B
Glucocorticoids are widely used in conjunction with chemotherapy for ovarian cancer to prevent hypersensitivity reactions. Our study we reveals a novel role for glucocorticoids in the inhibition of ovarian cancer metastasis. Glucocorticoids treatments induce the expression of miR-708, leading to the suppression of Rap1B, which result in the reduction of integrin-mediated focal adhesion formation, inhibition of ovarian cancer cell migration/invasion, and impaired abdominal metastasis in an orthotopic xenograft mouse model. Restoring Rap1B expression reverts glucocorticoids-miR-708 cascade-mediated suppression of ovarian cancer cell invasion and metastasis. Clinically, low miR-708 and high Rap1B are found in late state ovarian tumors, as compared to normal, and patients with high miR-708 show significantly better survival. Overall, our findings reveal an opportunity for glucocorticoids and their downstream mediators, miR-708 or Rap1B, as therapeutic modalities against metastatic ovarian epithelial cancer.
MicroRNA-149 targets GIT1 to suppress integrin signaling and breast cancer metastasis
Metastasis is the predominant cause of death in breast cancer patients. Several lines of evidences have shown that microRNAs can play an important role in cancer metastasis. Using isogenic pairs of low and high metastatic lines derived from a human breast cancer line, we have identified miR-149, to be a suppressor of breast cancer cell invasion and metastasis. We also identified GIT1 (G protein-coupled receptor kinase-interacting protein 1) as a direct target of miR-149. Knockdown of GIT1 reduced migration/invasion and metastasis of highly invasive cells. Re-expression of GIT1 significantly rescued miR-149-mediated inhibition of cell migration/invasion and metastasis. Expression of miR-149 impaired fibronectin-induced focal adhesion formation and reduced phosphorylation of FAK and paxillin, which could be restored by re-expression of GIT1. Inhibition of GIT1 led to enhanced protein degradation of paxillin and α5β1 integrin via proteasome and lysosome pathways respectively. Low level of miR-149 and high level of GIT1 was significantly associated with advanced stages of breast cancer as well as lymph node metastasis. It is concluded that miR-149 suppresses breast cancer cell migration/invasion and metastasis by targeting GIT1, suggesting potential applications of the miR-149/GIT1 pathway in clinical diagnosis and therapeutics.
Identification of Cancer as a Metabolic Disease and Development of Metabolism-based Therapies
Cancer cells are known to have metabolic requirements different from normal cells. This metabolic adaption is to accommodate the need for rapid increase of mass and to cope with the often nutrition and oxygen-deprived tumor microenvironment. Dr. Kung’s lab found that many types of cancer are addicted to external arginine which activates mTOR, a kinase involved in regulating cell metabolism and growth. Using arginine deiminase (ADI) to deprive external arginine, tumor, but not normal, cells were killed. This treatment is distinct from conventional genotoxic therapy in that it causes cell death through lethal autophagy, a “self-eating” process. As such, it complements the apoptosis-based therapy and can overcome drug resistance. Most strikingly, the cells die from “chromatin-autophagy”, where chromatins are leaked out of the nucleus and captured by autophagosome. This study not only uncovers a novel form of autophagy but also offers new strategy for cancer treatment. ADI is currently undergoing phase III trial. (PNAS (2014); Science Signaling (2014))
Patients infected with certain genotypes of HBV have a lower risk of hepatocellular carcinoma and exhibit a more favorable response to antiviral therapy than patients infected with other HBV genotypes. Using cultured human hepatoma cells as a model of HBV infection, we found that the expression of 2.2DS-RNA caused a decrease in HBV replication. In cultured cells, the ectopic expression of 2.2DS-RNA obviously reduced the intracellular levels of HBV mRNAs. Our analysis of the 2.2DS-RNA-mediated suppression of viral RNA expression showed that 2.2DS-RNA inhibited transcription via binding to the TATA-binding protein and stress granule proteins. Our findings suggest that the 2.2DS-RNA acts as a suppressive noncoding RNA that modulates HBV replication, which may in turn influence the development of chronic hepatitis B. (J Virol. (2015))
Dr. Huang’s research team was the first research team in Asia to publish a high EGFR mutation rate in non-small cell lung cancer (NSCLC) patients in 2004, which is related to the responsiveness of gefitinib, an EGFR tyrosine kinase inhibitor. This important finding suggest that Taiwanese lung cancer patients would have higher response rate to this new drug and will have benefit in prolonged survival. In the following years, her research team has published more than twenty EGFR mutation or TKI-related papers in NSCLC.
Neoplastic mutilnucleation in oncogene MCT-1 activation and loss of the tumor suppressor(s)
Multinucleation is often identified in cancer cells. Dr. Hsu’s lab found that multinucleate cells were greatly increased when oncogene MCT-1 is overexpressed and p53 is suppressed. Her lab found three interphase nuclei (arrow), a mitotic nucleus with chromosome alignment at the metaphase plate (star) and some micro-nuclei (asterisk) that were all enclosed within a single cell. This proves that unsynchronized cell cycle progression at different nuclear compartments of a multi-nuclear cell enable perpetuate the rate of aneuploidy and promote chromosomal instability during tumor progression. (Molecular Cancer Research. 2009, 7:536-548, Cover story)
Dr. Hsu’s lab further found that MCT-1 physically interacts with p190B and Src in vivo and induces the Src/p190B signaling function that inhibits RhoA activity in PTEN loss condition. Through MCT-1/Src/p190B/RhoA pathway, the incidences of mitotic catastrophe in spindle multipolarity and cytokinesis failure that drive neoplastic multinucleation are dramatically enhanced. Most important, targeting MCT-1 dramatically represses the Src/p190B signaling that improves nuclear structure and suppresses tumorigenicity of PTEN-null breast cancer cells. MCT-1 gene induction has now been recognized as a potential biomarker of breast cancer development. Abrogating MCT-1 activity may be promising stratagem for management of breast cancer. This study not only uncovers a novel mechanism of nuclear aberration but also offers new strategy for cancer treatment. (Oncogene. 2014. 33:5109-5120).
Smad3 is a major intracellular effector in the TGF-b signal transduction. Its function is regulated by phosphorylation of multiple sites. Our laboratory found a proline isomerase Pin1 binds to Thr-179 of Smad3 when it is phosphorylated. This study demonstrated a novel link between two important players in cancer development (J Biol Chem (2010) 285, 1754).
The nonsense mutations of the large hepatitis B virus (HBV) lsurface (S) (LHBS) gene have been reported to have oncogenic potential. We showed the transforming growth factor induced (TGFBI) gene is silenced in the NIH3T3 cells transfected with a nonsense mutant of LHBS. Since TGFBI is a potential tumor suppressor, the silence of TGFBI may be a key event for the LHBS nonsense mutant-induced oncogenesis (BBA Mol Basis Dis (2014) 1842, 1080).
Primary cutaneous amyloidosis (PCA) is a relatively common itchy skin disorder in South America and Southeast Asia. Genetic analysis identified a link between missense mutations in the IL-31 receptor subunits and familial cases of PCA patients. We established a cultured cell-based disease model by introducing the PCA-derived mutation in the IL-31RA subunit of the IL-31 receptor. We found the mutation in the receptor subunit reduces the MCP-1 production. We suggested this phenomenon may be important for the development of the disease. (J Invest Dermatol (2013) 133, 1375)
Development and Disease Models Research Group
Immunological cross talks between gut and other organs in the body
Immunological cross-talk between organs helps maintain the homeostasis of immune responses, thereby, enhancing immune protection of the host. For instance, when intestines are infected with harmful microbes, it not only would hamper intestinal health, but also trigger immunological reactions in other organs. Yet, the molecular mechanisms underlying the immunological communication remain unclear. Drosophila shares a similar innate immune system with humans and is an excellent genetic model system for studying inter-organ communication. Dr. Juang’s lab found that after the gut experiences bacterial stress, the increase of ROS in gut initiates an innate immune response in a remote organ fat body (analogous to human liver). This communication pathway is done via nitric oxide and hemocytes and another unknown messenger in carrying the ROS signal in the gut to the fat body, which then activates the Relish/NF-KB transcription factors and induces an antimicrobial peptide response in the fat body. The results of this study have been published in Cell Host & Microbe (2012), and is one of the stories that received a preview. This study’s importance is that it reveals that when an organism experience microbial threats in the gut, how would it signal other organs to induce immune response and protect it from harm, letting us better understand how to prevent immune-related diseases and further to therapeutic drug development.
CISD2 mediates life span in mammals
CISD2 gene is located within the candidate region on chromosome 4q where a genetic component for human longevity has been mapped. Dr. Tsai’s lab found that mouse Cisd2 deficiency drives premature aging and causes mitochondria-mediated defects in mice (G&D 2009). Interestingly, an age-dependent decrease in mouse Cisd2 expression has been detected during normal aging. Furthermore, Dr. Tsai’s lab demonstrated that a persistent level of Cisd2 achieved by transgenic expression in mice extends their median and maximum lifespan without any apparent deleterious side effects. Cisd2 also ameliorates age-associated degeneration of the skin, skeletal muscles and neurons. Moreover, Cisd2 protects mitochondria from age-associated damage and functional decline as well as attenuating the age-associated reduction in whole-body energy metabolism. These results suggest that Cisd2 is a fundamentally important regulator of lifespan, and provide an experimental basis for exploring the candidacy of CISD2 in human longevity (HMG, 2012).
Endoderm Gene Regulatory Networks in zebrafish
Many studies on the development of the liver in different model organisms have demonstrated that the mechanism of hepatogenesis is conserved in vertebrates. The identification of the genes and regulatory pathways involved in liver formation provides a basis for the diagnosis of liver diseases and therapeutic interventions. Liver derived from endoderm, Dr. Yuh therefore study the Gene Regulatory Networks (GRNs) of endoderm in order to understand the molecular mechanism of liver specific genes’ expression, eventually to derive some medical implications. Dr. Yuh has established the gene regulatory networks for zebrafish embryogenesis, functional dissecting the important subcircuits in the endoderm networks and published five papers.
Identification of the common regulators for hepatocellular carcinoma induced by hepatitis B virus X antigen in a mouse model
Hepatitis B virus X antigen plays an important role in the development of human hepatocellular carcinoma (HCC). The key regulators controlling the temporal downstream gene expression for HCC progression remains unknown. Dr. Yuh took advantage of systems biology approach and analyzed the microarray data of the HBx transgenic mouse, identified five common regulator genes: EDN1, BMP7, BMP4, SPIB and SRC. Up-regulation of the common regulators was validated in the other independent HBx transgenic mouse lines. Using the human HCC samples, Dr. Yuh found EDN1, BMP4 and BMP7 were up-regulated in cirrhosis; BMP4, BMP7, and SRC were further up-regulated in hepatocellular or cholangiocellular carcinoma samples. Overexpression of the common regulators increases the cell viability, promotes migration and invasiveness, and enhances the colony formation ability in Hep3B cells. The validation of the gene expressions in the liver cancer of human patients and their cellular function assays suggests that the identified common regulators may serve as useful molecular targets for the early-stage diagnosis or therapy for HCC. The results have been publishing on Carcinogenesis. 2012 Jan; 33(1):209-219
Liver-specific expressions of HBx and src in the p53 mutant trigger hepatocarcinogenesis in zebrafish
Hepatocarcinogenesis is a multistep process that starts from fatty liver and transitions to fibrosis and, finally, into cancer. Many etiological factors, including hepatitis B virus X antigen (HBx) and p53 mutations, have been implicated in hepatocarcinogenesis. However, potential synergistic effects between these two factors and the underlying mechanisms by which they promote hepatocarcinogenesis are still unclear. Dr. Yuh show that the synergistic action of HBx and p53 mutation triggers progressive hepatocellular carcinoma (HCC) formation via src activation in zebrafish. Liver-specific expression of HBx in wild-type zebrafish caused steatosis, fibrosis and glycogen accumulation. However, the induction of tumorigenesis by HBx was only observed in p53 mutant fish and occurred in association with the up-regulation and activation of the src tyrosine kinase pathway. Furthermore, the overexpression of src in p53 mutant zebrafish also caused hyperplasia, HCC, and sarcomatoid HCC, which were accompanied by increased levels of the signaling proteins p-erk, p-akt, myc, jnk1 and vegf. Increased expression levels of lipogenic factors and the genes involved in lipid metabolism and glycogen storage were detected during the early stages of hepatocarcinogenesis in the HBx and src transgenic zebrafish. The up-regulation of genes involved in cell cycle regulation, tumor progression and other molecular hallmarks of human liver cancer were found at later stages in both HBx and src transgenic, p53 mutant zebrafish. Dr. Yuh’s study demonstrates that HBx and src overexpression induced hepatocarcinogenesis in p53 mutant zebrafish. This phenomenon mimics human HCC formation and provides potential in vivo platforms for drug screening for therapies for human liver cancer. The results have been publishing on PLoS One 2013 Oct 9; 8(10):e76951
Functional Genomics Research Group
An integrative genomic analysis identifies Bhmt2 as a diet-dependent genetic factor protecting against acetaminophen-induced liver toxicity
Acetaminophen-induced liver toxicity is the most frequent precipitating cause of acute liver failure and liver transplant, but contemporary medical practice has mainly focused on patient management after a liver injury has been induced. An integrative genetic, transcriptional, and two-dimensional NMR-based metabolomic analysis performed using multiple inbred mouse strains, along with knowledge-based filtering of these data, identified betaine-homocysteine methyltransferase 2 (Bhmt2) as a diet-dependent genetic factor that affected susceptibility to acetaminophen-induced liver toxicity in mice. Through an effect on methionine and glutathione biosynthesis, Bhmt2 could utilize its substrate (S-methylmethionine[SMM]) to confer protection against acetaminophen-induced injury in vivo. Since SMM is only synthesized in plants, Bhmt2 exerts its beneficial effect in a diet-dependent manner. Identification of Bhmt2 and the affected biosynthetic pathway demonstrates how a novel method of integrative genomic analysis in mice can provide a unique and clinically applicable approach to a major public health problem. The finding was the cover story on Genome Research, Jan. 2010.
Klebsiella pneumoniae is a globally distributed pathogenic bacterium that is responsible for a broad spectrum of infections. Common sites for nosocomial Klebsiella infections include the urinary tract, lower respiratory tract, biliary tract, and surgical wound sites. Pyogenic liver abscess (PLA) is a complication of intra-abdominal or biliary tract infections, resulting from mixed aerobic and anaerobic bacterial infections. However, pyogenic liver abscess mediated by primary infection with invasive K. pneumoniae as a single pathogen has been reported in recent years. In Taiwan, the occurrence of PLA has been suggested to correlate with an increasing risk of colorectal cancer (CRC). K. pneumoniae is the leading PLA bacterial pathogen in Taiwan, of which K1 serotype-predominated. We have identified a pks colibactin gene cluster from a K. pneumoniae K1 strain through complete sequencing and comparative genomics analyses. The pks genotoxin is responsible for genotoxicity in cell and mice infection models. Accumulating evidences pointed to an association of the genotoxic phenotype with the virulent serotypes commonly identified among PLA patients in Taiwan. (PlosONE. 2014. 9:e96292)