Understanding myeloid heterogeneity in premetastatic niches following cytotoxic therapy

Primary Supervisor: Ioanna Keklikoglou, Queen Mary University of London

Secondary supervisor: Sophie Acton, UCL

Project

Chemotherapy is the standard of care for the management of locally advanced, invasive breast cancer. However, tumours often develop resistance to chemotherapy, while those that initially respond to the treatment eventually relapse, thus increasing the likelihood of metastasis formation. The tumour microenvironment has a fundamental role in fostering tumour resistance to chemotherapy regimens. Tumour-associated macrophages (TAMs) that infiltrate primary tumours limit the chemotherapeutic efficacy in mouse models of breast cancer (Hughes et al., 2015). Yet, the role of macrophages in mediating chemoresistance at pre-metastatic niches and metastatic tumours is so far poorly understood. We have recently shown that neoadjuvant chemotherapy enhances the propensity of breast cancer cells to metastasize via the induction of tumour-derived pro-metastatic extra-cellular vesicles (EVs). Importantly, we found that chemotherapy-elicited EVs interact with pulmonary endothelial cells and induce a pro-inflammatory response in the pre-metastatic niche, leading to enhanced accumulation of Ly6C+CCR2+ monocytes which support metastatic seeding (Keklikoglou et al., 2019). In spite of growing interest, this research field is still in its infancy: although previous studies have elucidated the role of CCR2+ monocytes in metastasis by facilitating cancer cell extravasation and promoting cell survival (Kitamura et al., 2015), how these cells and other metastasis-associated monocytic subpopulations respond to chemotherapy remains unknown.

This project will unravel how chemotherapy alters monocyte/macrophage function to support metastatic seeding and growth. By exploiting state-of-the art mouse models of cancer, as well as quantitative molecular and cellular approaches, we will elucidate the role of the non-malignant cellular components in pre-metastatic niches in supporting/facilitating metastatic cancer cell seeding and tumour growth in chemotherapy treated mouse models of breast cancer. The monocyte/macrophage subpopulations that facilitate metastasis formation in response to chemotherapy and the molecular pathways involved in this process will be identified by profiling at the single-cell level the transcriptomes of lung microenvironments exposed to chemotherapy. Furthermore, the origin of metastasis-associated macrophage subpopulations and their interaction with extravasating cancer cells and possibly other stromal cells of the pre-metastatic niche will be investigated using in vivo lineage tracing tools and multiphoton time-lapse live imaging (Acton et al., 2012; De Winde et al., 2021). Using either genetic or pharmacological approaches we will interrogate the mechanistic role of selected targets in re-programming metastasis-associated macrophages. Ultimately, this project may provide targets for therapeutic intervention.

Candidate background

The ideal candidate should have a strong background in molecular and cellular biology and previous laboratory experience. Experience in basic molecular biology and biochemistry techniques (qPCR, ELISA, Western Blot) as well as cell culture and flow cytometry is preferred. Previous experience with mouse models and analysis of functional genomic datasets (i.e. using R programming) is desired, but not mandatory.

Potential Research Placements

1. Mirjana Efremova, Barts Cancer Institute, Queen Mary University of London
2. Chris Tape, UCL Cancer Institute
3. Sophie Acton, UCL Cancer Institute

References

1. Hughes, R., Qian, B.-Z., Rowan, C., Muthana, M., Keklikoglou, I., Olson, O.C., Tazzyman, S., Danson, S., Addison, C., Clemons, M., et al. (2015). Perivascular M2 Macrophages Stimulate Tumor Relapse after Chemotherapy. Cancer Res. 75, 3479-3491.
2. Keklikoglou, I., Cianciaruso, C., Güç, E., Squadrito, M.L., Spring, L.M., Tazzyman, S., Lambein, L., Poissonnier, A., Ferraro, G.B., Baer, C., et al. (2019). Chemotherapy elicits pro-metastatic extracellular vesicles in breast cancer models. Nat. Cell Biol. 21, 190-202.
3. Kitamura, T., Qian, B.-Z., Soong, D., Cassetta, L., Noy, R., Sugano, G., Kato, Y., Li, J., and Pollard, J.W. (2015). CCL2-induced chemokine cascade promotes breast cancer metastasis by enhancing retention of metastasis-associated macrophages. J. Exp. Med. 212, 1043-1059.
4. Acton S., Astarita JL., Malhotra D., Lukacs-Kornek V., Franz B., Hess PR., Jakus Z., Kuligowski M., Fletcher AL., Kutlu GE., et al (2012). Podoplanin-Rich Stromal Networks Induce Dendritic Cell Motility via Activation of the C-type Lectin Receptor CLEC-2. Immunity 37, 276-289.
5. De Winde CM., George S., Crosas-Molist E., et al (2021). Podoplanin drives dedifferentiation and amoeboid invasion of melanoma. iScience 24, 102976.