E-Poster Presentation 34th Lorne Cancer Conference 2022

Deciphering the role of SULF1 in cancer stem cell function (#307)

Laura Rangel 1 2 , Felix Kohane 1 2 3 , Beatriz Perez-San Juan 1 2 , Heloisa Helena Milioli 1 2 , Vanina Rodriguez 1 2 , John G Lock 3 , Christine Chaffer 1 2
  1. Garvan Institute of Medical Research, Darlinghurst, NEW SOUTH WALES, Australia
  2. St Vincent's Clinical School, University of New South Wales Medicine, University of New South Wales, Sydney, NSW, Australia
  3. School of Medical Sciences, University of New South Wales, Sydney, NSW, Australia

Background: Triple-negative breast cancer (TNBC) is associated with a poor prognosis due to its propensity to recur in a metastatic and chemotherapy-resistant form. That tumour aggressiveness is driven by a highly specialised cancer cell subpopulation termed cancer stem cells (CSC). CSCs reside in a hybrid epithelial-mesenchymal (E/M) state and can arise from the dedifferentiation of their non-CSC counterparts via activation of the epithelial-to-mesenchymal transition (EMT). Therefore, identifying factors that drive the hybrid-E/M state may lead to new targeted therapeutic strategies. Transcriptomic analysis revealed that the sulfatase SULF1 is significantly upregulated in CSCs compared to non-CSCs. Hence, we hypothesize that SULF1 is essential for entrance into and maintenance of the CSC state.

 

Methods: We used single-cell imaging to identify cell states across the EMT spectrum in heterogeneous TNBC cell line models. Cells were immunostained for SULF1 and canonical EMT markers. Dimension reduction techniques were performed to classify E/M subpopulations. Then, Random Forests machine learning models were utilised to predict E/M cell states and determine the effect of SULF1 inhibition on CSC E/M state. In vitro and in vivo models were then used to determine the effect of SULF1 modulation on CSC function.

 

Results:  Immunofluorescence analysis combined with Random Forest machine learning models confirmed that SULF1 is upregulated in CSCs. In vitro knockdown of SULF1 induced an actin cytoskeleton reorganization and cell clustering, concomitant with higher expression of the epithelial marker E-cadherin, reminiscent of CSCs transition into an epithelial cell state. Noteworthy, using in vitro and in vivo models, we demonstrate that SULF1-downregulation inhibits CSC function by blocking tumour-initiation and metastatic potential.

 

Conclusion: This study shows that SULF1 is required for the maintenance of the aggressive CSC state in TNBC. Based on these data, inhibiting SULF1 may be novel therapeutic strategy for triple-negative breast cancer patients.

 

Future work: We are now using in vivo models to test whether SULF1-inhibition combined with chemotherapy significantly improves overall survival outcomes in pre-clinical models of TNBC and other cancers.