Elucidating the mechanisms via which the proto-oncogene PBF stimulates cell motility in thyroid tumour progression

Selvambigai Manivannan*, Merve Kocbiyik, Mohammed Alshahrani, Mohammed E. El-Asrag, Ling Zha, Katie Brookes, Hannah Nieto, Martin Read, Andrew Beggs, Christopher McCabe, Vicki Smith

*Corresponding author for this work

Research output: Contribution to journalAbstractpeer-review

Abstract

Background and Aims: The proto-oncogene pituitary tumor-transforming gene binding factor (PBF/PTTG1IP) is overexpressed in multiple tumours, including thyroid cancer, and is associated with tumour progression. In vitro, PBF potently induces cancer cell motility, and both Src-mediated phosphorylation at tyrosine 174 (Y174) and endocytosis of PBF are required for induction of thyroid and breast cancer cell migration and invasion. This study aimed to further elucidate the mechanisms by which PBF induces cancer cell motility.

Methods: To elucidate molecular events downstream of PBF overexpression, phosphoproteomic and RNA-Seq analyses of thyroid cells stably overexpressing PBF were performed. We then utilised a novel Pbf knockout (Pbf-/-) mouse model with CRISPR/Cas9-mediated deletion of Pbf exon 4 in C57BL/6N mice. Mouse embryonic fibroblasts (MEFs) were isolated at embryonic day 13.5 and used as primary cultures.

Results: Phosphoproteomic and RNA-Seq analyses revealed enrichment for molecules involved in cell adhesion and cytoskeleton organisation in response to PBF overexpression, prompting further investigation into a physiological role for PBF in cell motility. Pbf-/- MEFs showed a significant reduction in migration and invasion compared with wild-type (Pbf+/+) MEFs. Interestingly, heterozygote MEFs (Pbf+/-) showed an intermediate decrease in motility suggesting a gene-dosage effect. Additionally, the migration of Pbf-/- MEFs transfected with PBF was comparable with Pbf+/+ MEFs in rescue experiments. Initial immunofluorescent studies of Pbf-/- MEFs suggest alterations in focal adhesion (FA) structure and distribution. Importantly, Pbf-/- MEFs demonstrated a marked reduction in focal adhesion kinase (FAK) and paxillin staining with smaller, punctate and more radially distributed FAs compared with Pbf+/+ MEFs.

Conclusions: These findings further confirm a role for PBF in cell motility, through regulating cell adhesion and cytoskeleton organisation. Overall, these studies demonstrate a physiological role for PBF in cell motility and further elucidate the mechanisms by which PBF induces cell motility in thyroid tumour progression.
Original languageEnglish
Article numberPO2
Pages (from-to)6-6
Number of pages1
JournalThyroid Research
Volume16
Issue numberS1
DOIs
Publication statusPublished - 11 Jul 2023
Event71st Annual Meeting of the British Thyroid Association
- Royal College of Pathologists, London, United Kingdom
Duration: 9 Jun 20239 Jun 2023
Conference number: 71

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