Congratulations to our CSI Research Assistants, Ms Madhu Mathi Kanchi and Ms Eve Wang Chao, and PhD student, Ms Shreya Kar, from Dr Alan Prem Kumar’s group for winning awards at the International Conference on Scientific Frontiers in Natural Product Based Drugs (SFNPBD) 2017!
This conference was co-organized by the Department of Pharmacology, Yong Loo Lin School of Medicine, National University Health System, and the Department of Pharmacy, Faculty of Science, National University of Singapore, Singapore, and by the Pharmacological Society (Singapore). It was held from 6-7 July 2017 at National University of Singapore.
SFNPBD 2017 focused on the pharmacology, medicinal chemistry and pharmacy of natural product based drugs. International and local delegates with varied research skills were given the opportunity to share and discuss scientific findings and concepts. It also paved way to build new partnerships for the discovery and advancement of natural product based drugs.
Eve was pleased to see other researchers who were interested in natural product based drugs like her. Madhu shared that she felt elated to learn how many natural products are being used to prevent multiple ailments now.
Madhu Mathi Kanchi
Best Poster Scientific Presentation Award
Characterization of a Novel Vitamin E Analogue for Mitochondrial Dysfunction in Triple Negative Breast Cancer
Madhu Mathi Kanchi1, Fiona S Wong1,2, Karishma Sachaphibulkij3,4, Gautam Sethi2, Lina HK. Lim3, Henrik Ditzel5, Jiri Neuzil4, Alan Prem Kumar1,2
1 Cancer Science Institute of Singapore, National University of Singapore
2 Department of Pharmacology, Yong Loo Lin School of Medicine, National University of Singapore
3 Department of Physiology, Yong Loo Lin School of Medicine, National University of Singapore
4 School of Medical Science, Griffith University, Southport, Queensland, Australia
5 Department of Cancer and inflammation Research, University of Southern Denmark
OBJECTIVE: (1) Characterization of compound-X on mitochondria dysfunction through ETC (Electron transport chain) leading to oxidative stress in the inner mitochondrial membrane through STAT3 signaling. (2) Delineate the function of mitoSTAT3 binding to mtDNA to affect mitochondrial transcription that may alter mitochondrial function and biogenesis.
METHODS: A series of biological assays were used for all in vitro work. Balb-c nu/nu mice were injected subcutaneously with MDA-MB-231 cells at 1×106 cells per animal. As soon as tumors reached the volume of 30 mm3, mice were treated with Compound-X or solvent control given intraperitoneally twice per week for 4 weeks. NOD scid gamma mice were implanted with patient breast tumour tissue, grown as first generation xenograft in mammary fat pad. When tumours reached volume of ~50 mm3, mice (n=2 per group) were treated with either Compound-X or solvent control given intraperitoneally twice a week.
RESULTS: Exposure with Compound-X led to efficient shutdown of respiratory complexes in TNBC cells. In vivo efficacy of Compound-X was demonstrated using a mouse xenograft and patient-derived PDX models. Mechanistically, Compound-X led to mitochondrial dysfunction via elevation of reactive oxygen species generated from complex-I and complex-III of the ETC system. Interestingly, attenuation of phosphorylated STAT3 on ser727 (p-STAT3ser727) by Compound-X reaffirmed the involvement of mitochondrial respiration via mitoSTAT3.
CONCLUSION: These novel findings pave a path forward for developing novel mito-targetting anticancer drugs with high efficacy in TNBC.
Key words: Mitochondrial dysfunction, Electron transport chain (ETC), mitoSTAT3 activity, mtDNAtargets, triple negative breast cancer
Acknowledgements: APK is supported by grants from National Medical Research Council of Singapore, NCIS Yong Siew Yoon Research Grant through donations from the Yong Loo Lin Trust and by the National Research Foundation Singapore and the Singapore Ministry of Education under its Research Centers of Excellence initiative to Cancer Science Institute of Singapore, National University of Singapore.
Corresponding author: Dr. Alan Prem Kumar, E-mail: csiapk@nus.edu.sg, Tel: +65 651654546
Eve Wang Chao
Best Oral Scientific Presentation Award
Interplay between Mevalonate and Hippo Pathways Regulates DDX20 Transcription via YAP-TEAD Complex in Triple Negative Breast Cancer
Chao Wang1,2, Beiying Qiu3, Tingting Wang1, Vijay Pandey1, Jahnavi Kesavamatham10, Tuan Zea Tan1, Ruby Huang1,3,4,5, Peter E. Lobie1,2,5, Gautam Sethi1,2, Patrick J. Casey6, Celestial T. Yap5,7, Soo Chin Lee1,5,8, LIM Chwee Teck9, Nicholas Tolwinski10, Vinay Tergaonkar3,4, Marius Sudol3,7,9, Alan Prem Kumar1,2,11,12
1 Cancer Science Institute of Singapore, National University of Singapore
2 Department of Pharmacology, Yong Loo Lin School of Medicine, National University of Singapore
3 Institute of Molecular and Cell Biology (IMCB), ASTAR, Singapore
4 Department of Biochemistry, Yong Loo Lin School of Medicine, National University of Singapore
5 National University Cancer Institute of Singapore (NCIS), Singapore
6 Duke-NUS Graduate Medical School, Singapore
7 Department of Physiology, Yong Loo Lin School of Medicine, National University of Singapore
8 Department of Haematology-Oncology, National University Hospital, Singapore
9 Mechanobiology Institute of Singapore
10 Department of Biological Science, National University of Singapore
11 Curtin Medical School, Faculty of Health Sciences, Curtin University, Perth WA, Australia
12 Department of Biological Sciences, University of North Texas, Denton, TX, USA
OBJECTIVE: To evaluate if RNA helicase DDX20, highly expressed in Triple Negative Breast Cancer (TNBC) cells, could serve as a surrogate marker for simvastatin treatment response, and to explore the possible underlying signaling pathway that is invovlved.
METHODS: We first assessed correlation between 17 mevalonate pathway-related genes and expression of DDX20 in a cohort of 1325 breast cancer tumors. TNBC cells, MDA-MB-231, were then treated with simvastatin and mevalonate pathway intermediates to assess the alteration in DDX20 expression. In the mouse model, MDA-MB-231 cells were injected to tail veins of mice, groups of 8 mice each were injected intraperioneally with vehicle or 25mg/kg simvastatin 3 times a week for 6 weeks. The number of metastatic colonies formed was quantified and immunohistochemical (IHC) staining of DDX20 was carried out in the lung tissues.
RESULTS: Both in vitro and in vivo studies demonstrate that high triple negative breast cancer (TNBC) with high DDX20 is more sensitive to simvastatin than breast cancer with low DDX20 level. Exposure of TNBC cells to statins decreases DDX20 expression in a mevalonate pathway-dependent manner via RhoA. Similar activity was observed in tumor biopsies in mice and breast cancer patients. As a recent study reported the mevalonate pathway regulates YAP via RhoA, we have uncovered an interplay between DDX20 and YAP-TEAD complex.
CONCLUSION: DDX20 is a potential surrogate marker for simvastatin treatment response in breast cancer and a long term implication of our findings is the possibility of an effective combinatorial therapeutic intervention using statins (to suppress DDX20 gene expression) and a suitable first-line agent “for the kill” of invasive breast cancer.
Key words: DDX20; YAP; surrogate marker; simvastatin; breast cancer
Ackownledgements: This work is supported by a grant from the National Medical Research Council, Singapore to APK: Interplay between Mevalonate and Hippo Pathways Regulates DDX20 Transcription via YAP-TEAD Complex in Triple Negative Breast Cancer. NMRC OF-IRG (2017) S$991,000.
Corresponding author: Alan Prem Kumar, E-mail: csiapk@nus.edu.sg, Tel: +65 65165456
Shreya Kar
Best Poster Scientific Presentation Award
Crosstalk between PPAR? and Annexin A1 in Tumor-Associated Macrophages in Breast Cancer
Shreya Kar1,2, Tuan Zea Tan2, Ruby Yun-JuHuang1,3, Alan Prem Kumar1,2, Lina H.K.Lim4,5
1 Cancer Science Institute of Singapore, National University of Singapore
2 Department of Pharmacology, Yong Loo Lin School of Medicine
3 Department of Obstetrics and Gynaecology, National University Hospital, Singapore
4 Inflammation and Cancer Laboratory, Immunology Programme, Department of Physiology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore
5 NUS Graduate School for Integrative Sciences and Engineering, National University of Singapore, Singapore
OBJECTIVE: Tumor-associated macrophages(TAMs) choreograph various aspects of the tumor microenvironment. Macrophages exhibit cellular plasticity and can be polarized to M1/M2 subtypes in presence of different microenvironment “signals”. Peroxisome proliferator-activated receptor gamma(PPAR?) is a ligand-activated transcription factor expressed in macrophages, which has been shown to polarize macrophages towards the activated M2 phenotype in metabolic diseases. Annexin A1(ANXA1), an anti-inflammatory protein is highly expressed in metastatic breast cancer.
METHODS: TAMs expression was evaluated in the breast cancer patient samples. Percentage of TAMs was evaluated using flow cytometry in the breast tumors from MMTV mice along with the gene expression of PPAR? and ANXA1.Macrophage education by breast cancer cells was assessed by ex vivo differentiation of bone marrow derived macrophages(BMDMs) by flow cytometry, western blotting and mRNA expression.
RESULT: Clinically, we found that M2 TAMs were highly enriched in Claudin-low breast cancer subtype and was strongly associated with PPAR? and ANXA1 expression. In the MMTV mouse model, TAMs were higher in the breast tumors compared to the normal mammary tissues. Additionally, the BMDMs were skewed to a more M2 TAM-like phenotype upon co-culture with breast cancer cells as well as upon treatment with PPAR? agonist. Interestingly, upon treatment with the breast cancer conditioned media, expression of PPAR? along with its downstream targets was reduced in ANXAI-knockout BMDMs as compared to its wild type counterparts, suggesting a role of ANXA1 in regulating PPAR? activation.
CONCLUSIONS: This study demonstrates a novel role ANXA1 in regulating expression of PPAR? in the TAMs of breast tumor microenvironment. Further studies are underway to explore the signaling mechanism involved in governing this dynamic process.
Key words: Tumor-associated macrophages, Breast cancer, PPAR?, Annexin A1.
Acknowledgments: This project is funded by a grant from the National Medical Research Council of Singapore (R-185-000-257-112) to LL and National Medical Research Council of Singapore [R-713-000-177-511] to APK.
Corresponding author: Shreya Kar, E-mail : shreya.kar@u.nus.edu , Tel: (+65) 81655826