Professor Catharina Svanborg
An Interview with Dr. Catharina Svan borg on HAMLET from serendipity to clinic which she spoke about at the Medela breastfeeding and Lactation symposium. In this interview Catharina talks about the journey of discovering the component in breastmilk, HAMLET and the results of it when used as a drug to treat bladder cancer.
Professor Catharina Svanborg
Catharina Svanborg, MD, PhD, is an award-winning Professor of Clinical Immunology at Lund University, Sweden and Fellow of the Royal Swedish Academy of Science.
Prof Svanborg is highly respected and influential internationally, in particular in the study of the pathogenesis of infectious diseases, with over 400 published papers to her credit. Awards include Kennedy Visiting Professorship Award at Imperial College, London, the Domagk award, the non-restricted grant award (BMS), the Edwin H. Beachey Distinguished Visiting Professorship Award at the University of Tennessee, the Jubilee award of the Swedish Medical Society, the Nordic Söderberg award and the Scientist of the Year Award in 2014 from the independent foundation Research, Sweden.
A focus on mentoring has also distinguished her long career, and she has mentored 45 graduate students and numerous postdoctoral fellows who have gone on to become successful in various fields. Prof Svanborg also served as Principle Investigator at the Singapore Immunology Network from 2008 to 2010, and Visiting Professor at Imperial College in 2000.
Abstract: HAMLET - from serendipity to the clinic
HAMLET (Human α-lactalbumin made lethal to tumour cells) is a protein-lipid complex composed of two major human milk constituents. It is formed by the major whey protein α-lactalbumin after partial unfolding and binding to oleic acid, the most abundant fatty acid in human milk triglycerides. HAMLET induces apoptosis in tumour cells, but leaves fully differentiated cells unaffected. The lecture will summarize our information on the molecular characteristics of the complex, the mechanisms of tumour cell death and the effects of HAMLET in patients and tumour models.
a) Structure. HAMLET is formed when α-lactalbumin unfolds by releasing the strongly bound Ca2+ion. The unfolded protein exposes new fatty acid binding sites that fit oleic acid and is stabilized in a partially unfolded state by the lipid cofactor. The well-known function of α-lactalbumin is as a substrate specifier in lactose synthase, required for the formation of lactose and expression of milk from the mammary gland. Surprisingly, our data shows that this milk protein can gain yet another important function by undergoing this change in tertiary structure and binding the lipid cofactor. Relevance of this process for the breast-fed child is suggested by the acid pH in the stomach, which unfolds α-lactalbumin and releases oleic acid from milk triglycerides. The findings suggesting that HAMLET might be formed in vivo, and benefit the breast-fed child.
b) Mechanism of action. HAMLET kills >40 different lymphoma and carcinoma cell lines in vitro. The broad anti-tumour activity is due to a new mechanism of cell death. The dying cells show apoptosis-like features, but tumour cell death is independent of caspases and the p53 or bcl-2 genotype of the cells.
HAMLET enters the cytoplasm of tumour cells, and translocates to the nuclei, where it accumulates. In the cytoplasm, HAMLET targets proteasomes and mitochondria. In the nuclei, HAMLET binds strongly to histones and disrupts the chromatin. Microarray studies have shown marked response differences between tumour cells and healthy cells, and have identified potential effector mechanisms of cell death, which are being explored. HAMLET thus activates unifying death response pathways that remain active in and shared by tumour cells.
c) Therapeutic effects. HAMLET limits the progression of human glioblastomas, bladder cancer and colon cancer in relevant animal models. Therapeutic efficacy against skin papillomas was demonstrated in a placebo-controlled study, and in patients with bladder cancer, HAMLET triggers a rapid death response, leading to cell detachment and release into the urine.
HAMLET thus shows great promise as a new anti-cancer agent. The lack of tumour specific therapies remains a significant problem in oncology and many attempts are being made to identify new, more selective therapeutic targets. HAMLET is an interesting tool to understand conserved cell death mechanisms in tumour cells, and a new tool in tumour therapy.
- Svensson, M., Hakansson, A., Mossberg, A. K., Linse, S. and Svanborg, C. (2000). Conversion of alpha-lactalbumin to a protein inducing apoptosis. Proc Natl Acad Sci U S A 97, 4221-6.
- Hakansson, A., Svensson, M., Mossberg, A. K., Sabharwal, H., Linse, S., Lazou, I., Lonnerdal, B. and Svanborg, C. (2000). A folding variant of alpha-lactalbumin with bactericidal activity against Streptococcus pneumoniae. Mol Microbiol 35, 589-600.
- Kohler, C., Gogvadze, V., Hakansson, A., Svanborg, C., Orrenius, S. and Zhivotovsky, B. (2001). A folding variant of human alpha-lactalbumin induces mitochondrial permeability transition in isolated mitochondria. Eur J Biochem 268, 186-91.
- Svensson, M., Fast, J., Mossberg, A. K., Duringer, C., Gustafsson, L., Hallgren, O., Brooks, C. L., Berliner, L., Linse, S. and Svanborg, C. (2003). Alpha-lactalbumin unfolding is not sufficient to cause apoptosis, but is required for the conversion to HAMLET (human alpha-lactalbumin made lethal to tumor cells). Protein Sci 12, 2794-804.
- Svensson, M., Mossberg, A. K., Pettersson, J., Linse, S. and Svanborg, C. (2003). Lipids as cofactors in protein folding: stereo-specific lipidprotein interactions are required to form HAMLET (human alpha-lactalbumin made lethal to tumor cells). Protein Sci 12, 2805-14.
- Duringer, C., Hamiche, A., Gustafsson, L., Kimura, H. and Svanborg, C. (2003). HAMLET Interacts with histones and chromatin in tumor cell nuclei. J Biol Chem 278, 42131-42135.
- Gustafsson, L., Leijonhufvud, I., Aronsson, A., Mossberg, A. K. and Svanborg, C. (2004). Treatment of skin papillomas with topical alphalactalbumin-oleic acid. N Engl J Med 350, 2663-72.
- Fischer, W., Gustafsson, L., Mossberg, A. K., Gronli, J., Mork, S., Bjerkvig, R. and Svanborg, C. (2004). Human alpha-lactalbumin made lethal to tumor cells (HAMLET) kills human glioblastoma cells in brain xenografts by an apoptosis-like mechanism and prolongs survival. Cancer Res 64, 2105-12.
- Baltzer, A., Svanborg, C. and Jaggi, R. (2004). Apoptotic cell death in the lactating mammary gland is enhanced by a folding variant of alphalactalbumin. Cell Mol Life Sci 61, 1221-8.
- Casbarra, A., Birolo, L., Infusini, G., Dal Piaz, F., Svensson, M., Pucci, P., Svanborg, C. and Marino, G. (2004). Conformational analysis of HAMLET, the folding variant of human alpha-lactalbumin associated with apoptosis. Protein Sci 13, 1322-30.
- Fast, J., Mossberg, A. K., Svanborg, C. and Linse, S. (2005). Stability of HAMLET--a kinetically trapped alpha-lactalbumin oleic acid complex. Protein Sci 14, 329-40.
- Fast, J., Mossberg, A. K., Nilsson, H., Svanborg, C., Akke, M. and Linse, S. (2005). Compact oleic acid in HAMLET. FEBS Lett 579, 6095-100.
- Hallgren, O., Gustafsson, L., Irjala, H., Selivanova, G., Orrenius, S. and Svanborg, C. (2006). HAMLET triggers apoptosis but tumor cell death is independent of caspases, Bcl-2 and p53. Apoptosis 11, 221-33.
- Pettersson, J., Mossberg, A. K. and Svanborg, C. (2006). alpha-Lactalbumin species variation, HAMLET formation, and tumor cell death. Biochem Biophys Res Commun 345, 260-70.
- Brest, P., Gustafsson, M., Mossberg, A. K., Gustafsson, L., Duringer, C., Hamiche, A. and Svanborg, C. (2007). Histone deacetylase inhibitors promote the tumoricidal effect of HAMLET. Cancer Res 67, 11327-34.
- Mossberg, A. K., Wullt, B., Gustafsson, L., Mansson, W., Ljunggren, E. and Svanborg, C. (2007). Bladder cancers respond to intravesical instillation of HAMLET (human alpha-lactalbumin made lethal to tumor cells). Int J Cancer 121, 1352-9.
- Gustafsson, L., Aits, S., Onnerfjord, P., Trulsson, M., Storm, P. and Svanborg, C. (2009). Changes in proteasome structure and function caused by HAMLET in tumor cells. PLoS ONE 4, e5229.
- Pettersson-Kastberg, J., Mossberg, A. K., Trulsson, M., Yong, Y. J., Min, S., Lim, Y., O’Brien, J. E., Svanborg, C. and Mok, K. H. (2009). alphaLactalbumin, engineered to be nonnative and inactive, kills tumor cells when in complex with oleic acid: a new biological function resulting from partial unfolding. J Mol Biol 394, 994-1010.
- Aits, S., Gustafsson, L., Hallgren, O., Brest, P., Gustafsson, M., Trulsson, M., Mossberg, A. K., Simon, H. U., Mograbi, B. and Svanborg, C. (2009). HAMLET (human alpha-lactalbumin made lethal to tumor cells) triggers autophagic tumor cell death. Int J Cancer 124, 1008-19.
- Mossberg, A.-K., Puchades, M., Halskau, Ø., Baumann, A., Lanekoff, I., Chao, Y., Martinez, A., Svanborg, C. and Karlsson, R. (2010). HAMLET interacts with lipid membranes and perturbs their structure and integrity. PLoS One 5, e9384.
- Mossberg, A. K., Hou, Y., Svensson, M., Holmqvist, B. and Svanborg, C. (2010). HAMLET histones and chromatin in tumor cell nuclei. J Urol 183,1590-1597.
- Storm, P., Aits, S., Puthia, M. K., Urbano, A., Northen, T., Powers, S., Bowen, B., Chao, Y., Reindl, W., Lee, D. Y., Sullivan, N. L., Zhang, J., Trulsson, M., Yang, H., Watson J. D., and Svanborg, C. (2011). Conserved features of cancer cells define their sensitivity of HAMLET-induced death; c-Myc and glycolysis. Oncogene, 30, 4765–4779.
- Puthia, M, Storm, P, Nadeem, A, Hsiung, S, Svanborg, C. 2013. Prevention and treatment of colon cancer by peroral administration of HAMLET (human α-lactalbumin made lethal to tumour cells). Gut 63:131-142.
- Smith, K. (2013). Therapy: HAMLET takes a leading role on the colorectal cancer stage Nat Rev Gastroenterol Hepatol 10:126.
- Xie, Y, Min, S, Harte, NP, Kirk, H, O’Brien, JE, Voorheis, HP, Svanborg, C, Hun Mok, K. (2013). Electrostatic interactions play an essential role in the binding of oleic acid with α-lactalbumin in the HAMLET-like complex: a study using charge-specific chemical modifications. Proteins. 81(1): 1-17.
- Storm, P, Kjaer, Klausen T, Trulsson, M, Ho, CS J, Dosnon, M, Westergren, T, Chao, YX, Rydstrom, A, Yang, H, Pedersen, SF, Svanborg, C. (2013). A unifying mechanism for cancer cell death through ion channel activation by HAMLET. PLoS ONE 8(3): e58578.
- Ho, J., Sielaff, H., Nadeem, A., Svanborg, C., Gruber, G. (2015). The molecular motor F-ATP synthase is targeted by the tumoricidal protein HAMLET. J Mol Biol. 427(10):1866-74. doi: 10.1016/j.jmb.2015.01.024.
- Ho, J., Nadeem, A., Rydström, A., Puthia, M and Svanborg, C. (2015). Targeting of nucleotide-binding proteins by HAMLET - a conserved tumor cell death mechanism. Oncogene. doi: 10.1038/onc.2015.144.
- Nadeem, A., Ho, JCS., Sanborn, J., Rydström, A., Gettel, DL., Ngassam, VN., Klausen, TK., Pedersen, SF., Lam, M., Parikh, AN., and Catharina Svanborg (2015). Protein receptor-independent plasma membrane remodeling by HAMLET; a tumoricidal protein-lipid complex. Nature Scientific Reports, 5, 16432
Professor Catharina Svanborg