The Wistar Institute :: Meenhard Herlyn, D.V.M., D.Sc.

Overview

Research Programs

•	Gene Expression and Regulation
•	Immunology
•	Molecular and Cellular Oncogenesis

Cancer Center

Vaccine Center

Other Research Centers

Shared Facilities

Meenhard Herlyn, D.V.M., D.Sc.

Professor and Program Leader
Molecular and Cellular Oncogenesis Program
Associate Director for Translational Research, Wistar Institute Cancer Center
215-898-3950, Office
215-898-0980, Fax

Introduction

Research in the laboratory of Meenhard Herlyn centers on the basic mechanisms that govern normal cell function, or homeostasis. Knowing how cells and tissues orchestrate their intertwined purposes helps researchers establish what happens when things go awry, such as in cancerous tumors.

Research Interests
The normal and malignant tissue environment and the development of rational approaches to cancer therapy

Key words: Stem cells in tissue morphogenesis, signal transduction and tumor development and progression, targeted therapy

1. Modeling the normal and diseased human tissue microenvironment. Pluri-potent neural crest-like stem cells from the human dermis are differentiated into melanocytes to test the hypothesis that they represent the reservoir for melanocytes in the epidermis and are more prone to transformation than fully differentiated cells. We are also interested in studying how other cells and the matrix in the microenvironment play critical roles in differentiation and transformation and have developed a complex, three-dimensional model of human skin consisting of a dermis with fibroblasts embedded in collagen and an epidermis of multi-layered keratinocytes.
Another strategy for testing our hypotheses is to reprogram mature, pigment-producing melanocytes to neural crest-like stem cells. We have achieved de-differentiation by activation of Notch signaling. Notch-induced neural crest-like stem cells have similar functions as dermal stem cells. These models allow investigations on tissue regeneration.
The laboratory is then reconstructing each step in the melanoma progression cascade. Genes associated with melanoma are overexpressed or expression is silenced with short hairpin (sh) RNA constructs in lentiviral vectors. Our recent experiments suggest that as few as two genetic “hits” can induce malignant transformation of melanocytes if the microenvironment supports cells to survive the initial crisis. The synthetic skin model was expanded to organotypic cultures for esophagus. We can also introduce into each model endothelial cells forming a microcapillary network. Studies on interactions between tumor cells, fibroblasts and endothelial cells are done in three-dimensional models, in which cells are embedded into collagen to mimic the tumor microenvironment. Cells grown in tissue-like models display major changes in gene expression similar to those in animals and patients making them superbly suited for studies on cell-cell signaling, matrix formation, and drug resistance.

2. Therapeutic targeting of signaling pathways in cancer. We are defining the signal transduction pathways that are constitutively activated in melanoma and squamous cell cancer cells through autocrine and paracrine growth factors and genetic alterations. With shRNA in lentiviral vectors we are identifying those genes in tumor cells, stromal fibroblasts, and endothelial cells that are potential targets for therapy. In melanoma, the MAPK and PI3K pathways are primary targets for therapy but additional pathways are explored to not only induce cytostatic but cytotoxic effects. Therapy is increasingly guided by the genetic aberrations in tumors and we are developing combinations of drugs that take into account the genetic signature of tumors with the long-term goal of individualized cancer therapy. Up to now, we have collaborated with pharmaceutical companies to obtain compounds in early stages of preclinical and clinical development. Increasingly, we are collaborating with academic chemists and structural biologists to select and further develop compounds for tumor inhibition. High-throughput screening assays are being developed to identify new targets and new lead compounds for specific inhibition of cancer cells.

3. Tumor dormancy and therapy resistance. Dormancy of tumor cells can occur in primary lesions or at any time after metastatic dissemination and can last for many years. Our working hypothesis is that tumor-propagating cells are central for dormancy due to their non-proliferation or very slow turnover and their non-responsiveness to growth signals. We are delineating tumor dormancy in melanoma and characterizing sub-populations with a major focus on non-proliferating cells with high proliferation potential hypothesizing that these are critical for dormancy and therapy resistance. We are then defining the escape of tumor cells from dormancy for growth, invasion and metastasis and and developing strategies for therapy. Using our unique three-dimensional melanoma and squamous carcinoma models we are determining how microenvironmental cues drive gene activation that leads to a signaling cascade for proliferation and invasion.

LAB ROTATION PROJECTS FOR 2009-2010

Development of a lentiviral vector to disrupt vessel morphogenesis by targeting Notch genes.

Cross talk between the MAPK and AKT pathways in normal human melanocytes using adenoviral vectors.

Targeting BRAF and AKT in tissue-like models of melanoma with signaling antagonists and RNAi.

Human embryonic stem cell differentiation to melanocytes.

Matrix differentiation of dermal and epidermal stem cells.

Dedifferentiation of melanocytes to multi-potent stem cells.

Selected Publications

Noma, K., Smalley, K.S.M., Lioni, M., Naomoto, Y., Tanaka, N., El-Deiry, W., King, A.J., Nakagawa, H., Herlyn, M.: An essential role for stromal fibroblasts and transformating growth factors (TGF)-ß in esophageal squamous cell carcinoma-induced angiogenesis. Gastroenterology 134: 1981-1993, 2008. PMID18439605

Tsai, J., Lee, J.T., Wang, W. Zhang, J., Cho, H., Mamo, S., Bremer, R., Gilette, S., Kong, J., Haass, N.K., Sproesser, K., Li, L., Smalley, K.S.M., Fong, D., Zhu, Y-L., Marimuthu, A., Nguyen, H., Lam, B., Liu, J., Cheung, I., Rice, J., Suzuki, Y., Liu, C., Settachatgul, C., Shellooe, R., Cantwell, J., Kim, S-H, Schlessinger, J., Zhang, K.Y.J., West, B., Powell, B., Habets, G., Zhang, C., Ibrahim, P.N. Hirth, P., Artis, D.R., Herlyn, M., Bollag, G.: Discovery of a novel selective inhibitor of oncogenic B-Raf kinase with potent anti-melanoma activity. Proc. Nat. Acad. Sc. (USA) 26: 3041-3049, 2008. PMID18287029

Smalley, K.S.M., Contractor, R., Nguyen, T.K., Xiao, M., Medinca, A., Edwards, R., Muthusamy, V., King, A.J., Flaherty, K.T., Bosenberg, M., Herlyn, M., Nathanson, K.L.: Identification of a novel sub-group of melanomas with kit/cyclin-dependent kinase-4 overexpression. Cancer Res. 68: 5743-5752, 2008. PMID18632627

Yu, H., McDaid, R., Lee, J., Possik, P., Kumar, S.M., Elder, D.E., van Belle, P., Gimotty, P., Guerra, M., Hammond, R., Nathanson, K.L., Dalla Plama, M., Herlyn, M, Xu, X.: Role of BRAF mutation and p53 inactivation during transformation of a sub-population of primary human melanocytes. Am. J. Pathol. April 23 [Epub ahead of print], 2009. PMID19389934

Smalley, K.S.M., Lioni, M., Palma, M.D., Xiao, M., Desai, B., Eghazi, S., Hansson, J., W, H., King, A.J., Flaherty, K.T., Herlyn, M., Nathanson, K.L.: Cyclin D1 mediates BRAF inhibitor resistance in a sub-set of BRAF-V600E mutated melanomas. Molec. Can. Ther: 7: 2876-2883, 2008. PMID18790768

Lioni, M., Noma, K, Snyder, A., Rustgi, A., Diehl, J.A. , Herlyn, M., Smalley, K.: Bortezomib-induced cellular stress via the p38 MAPK pathway leads to a DNA damage response and apoptosis in esophageal squamous cell carcinoma cells. Molec. Cancer Ther:7: 2866-2875, 2008. PMID18790767

Smalley, K.S.M., Xiao, M., Villanueva, J., Nguyen, T.K., Flaherty, K.T., Letrero, R., Nathanson, K.L., Herlyn, M.: CRAF inhibition induces Bcl-2 dependent apoptosis in melanomas with non V600E BRAF mutations. Oncogene 28: 85-94, 2009. PMID18794803

Pinnix, C. C., Lee, J.T., Liu, Z-J. McDaid, R., Balint, K., Beverly, L.J., Brafford, P.A., Xiao, M., Himes, B., Zabierowski, S.E., Yashiro-Ohtani, Y., Nathanson, K.L., Bengston, A., Pollock, P.M., Weeraratna, A.T., Nickoloff, B.J., Pear, W.E., Capobianco, A.J., Herlyn, M.: Active Notch1 protein confers a transformed phenotype to primary human melanocytes. Cancer Res., in press.

Meenhard Herlyn, D.V.M., D.Sc.