Poster Presentation 36th Lorne Cancer Conference 2024

Eribulin reduces sunitinib resistance by reversing hypoxia and epithelial mesenchymal transition associated metabolic reprograming in preclinical human clear cell renal carcinoma model. (#144)

Revati Sharma 1 , Rodney Luwor 1 2 , Ruth Escalona 1 3 , Prashanth Prithviraj 1 , George Kannourakis 1 , Nuzhat Ahmed 1 3
  1. Fiona Elsey Cancer Research Institute, Ballarat, VIC, Australia
  2. Royal Melbourne Hospital, University of Melbourne, Parkville, Melbourne, VIC, Australia
  3. Centre for Reproductive Biology, Hudson Institute of Medical Research, Clayton, Melbourne, VIC, Australia

Background: Clear cell renal cell carcinoma (ccRCC), a highly aggressive cancer, constitutes 85% of kidney cancers. Sunitinib is the first drug approved for advanced RCC. Despite its clinical benefits, sunitinib resistance emerge in patients, attenuating its primary improved patient survival outcomes.  Eribulin, a non-taxane microtubule-targeting agent, has shown good clinical efficacy in some cancers. In this study we investigated the molecular basis of sunitinib resistance in ccRCC and used eribulin to reverse that resistance in a preclinical model of ccRCC.

Methods: Sunitinib induced resistance was developed in ccRCC 786-O cell line by continuous exposure to the drug for 6 months. Morphological assessment of the cells was done by phase contrast microscope, chemosensitivity (IC50 values) to sunitinib was evaluated by MTT assay, scratch assay was performed to assess migration. The expression of different EMT and cancer stem cell (CSC)-associated markers in cell lines was analysed by qRT-PCR and western blot. Balb/c nude mouse model was used to determine the effect of eribulin on the growth of sunitinib resistance tumours.

Results: Sunitinib resistant ccRCC cells were two-fold more resistant to sunitinib than the parental cell line. Sunitinib resistance induced a significant nuclear and cellular hypertrophy resulting in slower migration than the parental untreated cells. Resistant cells showed a classic EMT and CSC-like pattern with significantly decreasing E-cadherin and increasing N-cadherin, TGF-b1, CD44, CD133 and CD105 expressions. The resistant cells had upregulated Glut1 and hexokinase (HK) expression with lower pyruvate kinase M2 (PKM2) and pyruvate dehydrogenase kinase 1 (PDK1) levels.

When subcutaneously xenografted in mice, the parental cell line failed to develop tumours. However, sunitinib resistant cells developed substantially big tumours within six weeks, which was decreased in volume substantially by two weekly intraperitoneal injections of eribulin with alleviation of mesenchymal and hypoxia-associated characteristics with reprogramed cholesterol biosynthesis.  Nonetheless, when left untreated for a week these mice redeveloped the tumours.

Conclusions: Our results indicate that sunitinib resistance in ccRCC is intrinsically associated with hypoxia and EMT. Eribulin targets both hypoxia and EMT resulting in a favourable tumour microenvironment which leads to reduced tumour growth which may be of clinical benefit to ccRCC patients.