“Hepsin/TMPRSS family members do not only promote cancer invasion, but they also help the coronavirus SARS-CoV-2 to infect cells”

Normally, epithelial cells are separated from neighboring tissues by a blanket- or sheet-like basement membrane. However, when cancer arises the overactive cell surface serine proteases damage the basement membrane. This enables cancerous epithelial cells to invade neighboring tissues, and ultimately metastasize to distant sites. Many cancer-promoting cell surface serine proteases belong to the Hepsin/TMPRSS family.

Interestingly, recent evidence suggests that the hepsin/TMPRSS family members not only promote cancer invasion, but they also help the coronavirus SARS-CoV-2 to infect cells. This may lead to the life-threatening COVID-19 coronavirus disease. The Klefström laboratory has been identifying and developing chemical and pharmacological inhibitors against hepsin/TMPRSS family members for a long time with the goal of preventing cancer invasion. Some of our drugs or drug-like molecules could be repurposed to prevent SARS-CoV-2 entry to the cells, potentially offering a fast-track treatment option for the COVID-19 disease. We are currently testing a number of hepsin/TMPRSS family-targeting drug-like molecules and drugs as potential antivirals as weapons in the battle against coronavirus.

Discovery of Selective Matriptase and Hepsin Serine Protease Inhibitors: Useful Chemical Tools for Cancer Cell Biology.

Damalanka VC, Han Z, Karmakar P, O’Donoghue AJ, La Greca F, Kim T, Pant SM, Helander J, Klefström J, Craik CS, Janetka JW.

J Med Chem. 2019 Jan 24;62(2):480-490. doi: 10.1021/acs.jmedchem.8b01536. Epub 2019 Jan 4.

Design, Synthesis, and Testing of Potent, Selective Hepsin Inhibitors via Application of an Automated Closed-Loop Optimization Platform.

Pant SM, Mukonoweshuro A, Desai B, Ramjee MK, Selway CN, Tarver GJ, Wright AG, Birchall K, Chapman TM, Tervonen TA, Klefström J.

J Med Chem. 2018 May 24;61(10):4335-4347. doi: 10.1021/acs.jmedchem.7b01698. Epub 2018 May 14.

Analyzing the Type II Transmembrane Serine Protease Hepsin-Dependent Basement Membrane Remodeling in 3D Cell Culture.

Pant SM, Belitskin D, Ala-Hongisto H, Klefström J, Tervonen TA.

Methods Mol Biol. 2018;1731:169-178. doi: 10.1007/978-1-4939-7595-2_16.

Deregulated hepsin protease activity confers oncogenicity by concomitantly augmenting HGF/MET signalling and disrupting epithelial cohesion.

Tervonen TA, Belitškin D, Pant SM, Englund JI, Marques E, Ala-Hongisto H, Nevalaita L, Sihto H, Heikkilä P, Leidenius M, Hewitson K, Ramachandra M, Moilanen A, Joensuu H, Kovanen PE, Poso A, Klefström J.

Oncogene. 2016 Apr 7;35(14):1832-46. doi: 10.1038/onc.2015.248. Epub 2015 Jul 13.

Immune checkpoint (IC) inhibitors have revolutionized cancer treatment by offering treatment options for previously incurable forms of cancer. However, IC inhibitor monotherapy is not effective against so-called ‘non-immunogenic’ cancers, such as breast cancer. Thus, a clear unmet medical need exists to increase effectiveness of immunotherapy in such cancers. One way to trigger an immune reaction against “non-immunogenic” tumours is induction of immunogenic cell death (ICD), which activates the innate immune system through release of danger-associated molecular patterns (DAMPS). For example, some types of chemotherapy induce ICD through cytotoxic effects, which elicits an immune response that is subsequentially often dampened through upregulation of checkpoint ligands. However, chemotherapy often has quite severe adverse effects that negatively impact quality of life. Therefore, a major opportunity in cancer treatment is to identify more cancer-specific, less toxic alternatives to induce ICD, which is the aim of this project.

Now we will screen a library of candidate cancer drugs in several breast cancer ICD-reporter cell lines we created. To shorten the time to clinical application, a chemical libraries containing approved and emerging investigational drugs will be used. The most promising candidates will be studied in vitro (in cell lines and in monocyte-derived dendritic cells (MDDCs)), ex vivo (in PDEC) and in vivo.

MYC is an oncogene and a transcription factor that is overexpressed in over 40% of breast cancers (Haikala et al., 2017). MYC supports cancer cell division by promoting cell cycle progression, and by switching cell metabolism to serve growth-promoting metabolism. MYC activation induces a metabolic switch characterized by enhanced glucose and glutamine utilization as well as by instructing the normally ATP- generating citric acid cycle to serve biosynthetic reactions. We found that the metabolic changes induced by MYC lead to decreased production of ATP and the consequent activation of a key cellular energy sensor protein AMP-activated kinase (AMPK) (Nieminen et al., 2013). We also found, that MYC-induced AMPK activity makes the cells more sensitive to apoptotic cell death, providing important new insight into the close connections between the MYC oncogene, cell death sensitivity and cancer metabolism.

Furthermore, we study how the altered metabolism-derived sensitivity to apoptosis could be exploited as a potential therapeutic strategy to kill cancer cells. We have discovered novel synthetic lethal and combination therapy- based approaches to harness MYC’s full apoptotic potential to pharmacologically activate apoptotic cell death in cancer cells (Haikala et al., 2016, Haikala et al., 2017).

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In order to properly perform their function, epithelial tissues need to maintain a pre-defined architecture. This structure is built via the localization and polarized orientation of the cells that constitute the tissue. Classical examples of epithelial tissues include skin with important barrier function and secretion glands, for example, milk producing mammary gland.

If the structurally organized epithelial cells lose contact with the rest of the structure or polarized orientation, this will affect to their ability control proliferation or cell death regulation. These defects in epithelial integrity can lead to tissue malfunction and development of epithelial pre-cancerous lesions or full-blown cancer.

Specific cell signaling circuitries are responsible for providing cues that help epithelial cells to organize into tissue structures. We aim to understand how cancer gene mutations affect to these signaling pathways in a way that predisposes the epithelial tissues to development of breast cancer.

For more information about this resaerach line, see

Breaking the epithelial polarity barrier in cancer: the strange case of LKB1/PAR-4

Par6 family proteins in cancer

Par6G suppresses cell proliferation and is targeted by loss-of-function mutations in multiple cancers

Cancer cell lines have been proven to be a valuable source of information for drug discovery process, but their limitations have been increasingly recognized. Culturing cells in 2D conditions will cause a lack of original complexity and heterogeneity of the tumor in situ. Chemicophysical cues from the surrounding stroma and cell- cell /cell- ECM interactions are also lacking from 2D cultures. This tumor-stroma interaction is particularly important since it affects cell signaling, proliferation, cell survival, and therefore has an impact on drug sensitivity and responses. For these reasons there has been an increasing interest in creating artificial models by implanting malignant tissues in three-dimensional culture systems and bioreactors. The advantage of these systems (patient derived ex vivo, pdex) is that the conditions are more controllable, they allow higher throughput studies, shorter time to achieve results with lower costs, and free of experimental animal use. In the past several years, a tremendous effort has been put into a development of 3D culture systems and adopting them in drug discovery, cancer cell biology, and stem cell studies. The biggest challenges of 3D models are to maintain the viability of tumor samples in long term cultures and preventing them for changing their cellular identity, and the overall heterogeneity of the original tumor during culture period. We have developed in collaboration with molecular material specialists from Aalto University a novel cellular identity preserving 3D model, which we are using to reveal those fundamental molecular mechanisms regulating cellular identity in mammary gland and in breast cancer. Realizing both the chemical and mechanical properties of microenvironment, which are constantly been altered through tissue remodeling (proliferation, apoptosis, migration), affects directly gene expression profiles, opens up new research directions to design new approaches in cancer research but also for regenerative medicine, developmental, and cell biology.

Our recent investigations have exposed a role for tumor suppressor LKB1 in maintenance of cell junction integrity in mammary epithelial cells. Loss of LKB1 damages tight junctions and desmosomes, which leads to redistribution of proteins that normally reside in desmosomes, including a transmembrane serine protease hepsin. The redistributed hepsin inflicts damage to basement membranes, thus paving a way to dissemination of cancerous cells (Partanen et al PNAS 2012).

Type II transmembrane serine protease hepsin is overexpressed and redistributed in clinical breast cancer samples, although the HPN gene is not a frequent target of cancer-specific genetic alterations. Our aim is to identify cancer relevant upstream factors responsible for oncogenic deregulation of hepsin and cancer promoting downstream consequences of uninhibited hepsin action. We are also currently investigating different therapeutic approaches to inhibit hepsin as a possible strategy to limit cancer growth and invasion (Tervonen et al. Adv. Cancer Res 2011; Partanen et al. Philos Trans R Soc Lond B Biol Sci 2013; Tervonen et al. Oncogene 2016).