Molecular Mechanisms of Metastasis

In Argentina, breast cancer is the leading cause of death among women, according to the National Cancer Institute.
There are different subtypes of breast cancer, and each is treated differently. Our laboratory focuses on the triple-negative subtype (TNBC), which means it lacks the molecular markers for which specific therapies currently exist. Therefore, it is primarily treated with chemotherapy. Unfortunately, 35% of patients are resistant to this therapy, and the tumor returns in the form of metastases, which are even more difficult to treat. For this reason, the identification of molecular markers and specific therapeutic targets is an unmet medical need in TNBC.

Our central research question is to investigate the molecular mechanisms through which tumor cells evade this treatment and establish metastases. To this end, we study the regulation and function of a transcription factor called Runx1, which regulates the expression of genes that can control cellular fate in mammary epithelial cells. To test our hypotheses, we use cultured human tumor cell lines, patient samples from a tumor bank, and molecular and cellular biology techniques.

Triple-negative breast cancer (TNBC) is a subtype of breast cancer defined by the absence of expression of the most common biomarkers/therapeutic targets in breast cancer, such as the estrogen receptor (ER), the progesterone receptor (PR), and human epidermal growth factor receptor 2 (HER2). Because of this characteristic, TNBC is one of the most aggressive subtypes for which there is still no effective specific therapy, with chemotherapy being the most commonly used clinical option. The lack of a therapeutic target leads to a risk of early recurrence, between 1 and 3 years, and an increased mortality rate within the first 5 years, significantly higher than in non-TNBC tumors. Initially, most TNBCs respond to chemotherapy; however, 35% of patients develop metastases after treatment. The identification of biomarkers leading to effective therapy for patients with TNBC is an unmet clinical need. For this reason, a better understanding of the molecular processes leading to chemotherapy resistance is key to designing strategic therapies that help prevent the development of metastases and, ultimately, improve patient survival.

In particular, the TNBC subtype is associated with the epithelial-mesenchymal transition (EMT), a process involved in the development of more invasive cellular phenotypes that promote metastasis, which may play a role in the development of chemotherapy resistance in breast tumors. This transition appears to be mediated by the generation/enrichment of tumor stem cells, opening up a new area of research in the search for a more effective therapy to overcome the drug resistance observed in TNBC.

We have recently demonstrated that the transcription factor RUNX1 is capable of increasing the expression of oncogenes and decreasing that of tumor suppressor genes in TNBC cell lines (Recouvreux et al. 2016). Furthermore, we demonstrated that RUNX1 is necessary for tumor cell migration in TNBC cell lines (Recouvreux et al. 2016). More importantly, it has been reported that RUNX1 expression correlates with a poorer prognosis in patients with TNBC (Ferrari et al 2014).

Our research project investigates the role of RUNX1 in tumor progression processes in human triple-negative breast cancer (TNBC).

The questions that keep us up at night are:

• Does RUNX1 play a role in the development of resistance to chemotherapy in TNBC?
• Is RUNX1 involved in androgen receptor signaling in LAR-negative triple-negative breast cancer (TNBC-LAR)?

In our laboratory, we use patient samples, cell lines in culture, and molecular and cellular biology. We employ loss-of-function and/or gain-of-function approaches involving RUNX1 to assess its oncogenic potential in TNBC. We are interested in studying the molecular mechanisms in which RUNX1 is involved in order to, in the future, attempt to control the disease.

We collaborate with other groups:
1) Matías Blaustein, PhD (iB3-DeFBMC-UBA).
2) Jennifer Richer, PhD (School of Medicine, University of Colorado, USA).
3) Ana Raimondi, PhD (IFIBYNE-UBA-CONICET).
4) Claudia Lanari, PhD (IBYME-CONICET).

Selected publications:

• RUNX1 is regulated by androgen receptor to promote cancer stem markers and chemotherapy resistance in triple negative breast cancer. NB Fernández, SM Sosa, JT Roberts, MS Recouvreux, L Rocha-Viegas, JL Christenson, NS Spoelstra, FL Couto, AR Raimondi, JK Richer & N Rubinstein. Cells; 2023 – Special Issue: RUNX Family in Cancer. https://doi.org/10.3390/cells12030444
• Covalent coupling of Spike’s Receptor Binding Domain to a Multimeric Carrier produces a high immune response against SARS-CoV-2. Rubinstein N* and Consortium Anti-covid*. Scientific Report; 2022 https://doi.org/10.1038/s41598-021-03675-0
  *All consortium equally contribution and corresponding authors.
• The interactions of Bcl9/Bcl9L with β-catenin and Pygopus promote breast cancer growth, invasion and metastasis. V Vafaizadeh, D Buechel, N Rubinstein, R Kalathur, L Bazzani, M Saxena, T Valenta, G Hausmann, C Cantu, K Basler and G Christofori. Oncogene; 2021. https://doi.org/10.1038/s41388-021-02016-9
• Parsing β-catenin’s cell adhesion and Wnt signaling functions in malignant mammary tumor progression. D Buechel, N Rubinstein*, N Sugiyama*, Meera Saxena*, Ravi K.R. Kalathur*, F Lüönd, V Vafaizadeh, T Valenta, G Hausmann, C Cantù, K Basler and G Christofori. PNAS; 2021. https://doi.org/10.1073/pnas.2020227118
  *contribuyeron de la misma manera
• Structural and Functional Comparison of SARS-CoV-2-Spike Receptor Binding Domain Produced in Pichia pastoris and Mammalian Cells. Rubinstein N* and Consortium Anti-covid*. Scientific Report; 2020. DOI: 10.1101/2020.09.17.300335
  *All consortium equally contribution and corresponding authors.
• A Pygopus 2-histone interaction is critical for cancer cell de-differentiation and progression in malignant breast cáncer. M Saxena, N Rubinstein*, RK Kalathur*, A Vettiger, N Sugiyama, M Neutzner, M Coto-Llerena, V Kancherla, C Ercan, S Piscuoglio, J Fischer, E Fagiani, C Cantù, K Basler & G Christofori. Cancer Research, 2020. DOI: 10.1158/0008-5472.CAN-19-2910
  *contribuyeron de la misma manera.
• R-spondin3 is associated with basal-progenitor behavior in normal and tumor mammary cells. J M. Tocci, C M. Felcher, M García Solá, M V Goddio, M N Zimberlin, N Rubinstein, et al & E Kordon. Cancer Research; 2018. doi: 10.1158/0008-5472.CAN-17-2676.
• Angiotensin-(1-7) counteracts the transforming effects triggered by angiotensin II in breast cancer cells. N Cambados, T Walther, K Nahmod, J M Tocci, N Rubinstein, I Böhme, et al & and C Schere-Levy. Oncotarget; 2017. doi: 10.18632/oncotarget.19290.
• RUNX1 and FOXP3 interplay regulates expresión of breast cancer related genes. MS Recouvreux, EN Grasso, PC Echeverria, L Rocha-Viegas, L Castilla, C Schere-Levy, JM Tocci, EC Kordon and N Rubinstein. Oncotarget; 2016. doi: 10.18632/oncotarget.6771.
• Mechanical strain induces involution-associated events in mammary epithelial cells. Quaglino A, Salierno M, Pellegrotti J, Rubinstein N & Kordon EC. BMC Cell Biol. 2009 Jul 17;10(1):55. doi: 10.1186/1471-2121-10-55
• Targeted inhibition of galectin-1 gene expression in tumor cells results in heightened T cell-mediated rejection; A potential mechanism of tumor-immune privilege. Rubinstein N, Alvarez M, Zwirner NW, Toscano MA, Ilarregui JM, Bravo A, et al & Rabinovich GA. Cancer Cell. 2004; 5:241-51. PMID: 15050916.  Artículo seleccionado para el arte de tapa en la edición de su publicación. Comentado en la revista Nature: 2004; 4:328.
• Lista completa en: http://bit.ly/3Ioujgi