SFEBES2023 Oral Communications Neuroendocrinology and Pituitary (6 abstracts)
1Queen Mary University of London, London, United Kingdom. 2UCL Queen Square Institute of Neurology, London, United Kingdom. 3Postgraduate Institute of Medical Education and Research, Chandigarh, India
Background: There is no effective medical treatment available for non-functioning pituitary neuroendocrine tumours (NF-PitNETs). Recurrence (7-12%) or incomplete resection (30-45%) is a common feature. Thus, finding novel medical therapies to help the management of these tumours would be of great value. By using high-throughput mass spectrometry combined with functional characterisation, we explored novel therapeutic targets for NF-PitNETs.
Methods: Tandem mass tag-based mass spectrometry was performed on 20 frozen tissue samples (non-recurrent (n =15), recurrent (n =5)) from patients with clinically nonfunctioning PitNETs. We used RT-qPCR (n =20) and immunohistochemistry (n =50) to confirm our results. Cell viability, invasion & migration, and wound healing assays were performed in mouse gonadotroph cell lines (αT3-1 and LβT2 cells) and primary human tumour cells from NF-PitNETs.
Results: Proteomic analysis showed upregulation of 31 proteins of the CDC42 signalling pathway members in recurrent NF-PitNETs, and increased CDC42 expression was confirmed by immunohistochemistry compared to normal pituitaries (<0.0001), with the higher expression in recurrent compared to non-recurrent (P=0.02). Proliferative tumours (Trouillas category 1b and 2b) showed increased CDC42 gene and protein expression compared to non-proliferative tumours (1a and 2a) (P=0.04). Significant time- and dose-dependent decrease in cell viability was seen in αT3-1 and LβT2 cells upon treatment with CDC42 pathway inhibitors MBQ-167 (P<0.0001), ML141 (P=0.0005) and FRAX486 (P<0.0001). These agents also showed cytotoxic effect on primary human NF-PitNET cells (n =18) (P<0.0001). Significant inhibition was observed in ML141-treated cells in migration assays (αT3-1, P=0.006; LβT2, P=0.0006), as well as in transwell invasion assays at 24 hrs (αT3-1, P<0.0001; LβT2, P=0.01), and 48 hrs (αT3-1, P=0.01; LβT2, P=0.03).
Conclusion: Our results demonstrate that CDC42 pathway is especially upregulated in recurrent NF-PitNETs. The potent inhibitory effect of ML141 on proliferation, migration and invasion of gonadotroph cell lines and human tumour cells in primary culture points to a therapeutical effect.