Endocrine Abstracts (2012) 29 P787

Expression of a novel isoform of thyroid peroxidase (TPO) gene in breast cancer (BC)

I. Muller1, C. Giani1, E. Fiore1, V. Belardi1, S. Sabatini1, V. Rosellini1, N. Funel1, D. Campani1, F. Grennan-Jones2, L. Zhang2, M. Lewis2, A. Bakhsh2, M. Roncella1, M. Ghilli1, A. Pinchera1, P. Vitti1, C. Dayan2 & M. Ludgate2


School of Medicine, Cardiff University, Cardiff, United Kingdom.


Introduction: BC patients have a high prevalence of anti-TPO-autoantibodies (TPOAb), which seem to be protective in BC patients. We hypothesized the presence of T-lymphocytes citotoxicity against a common antigen between thyroid and BC cells.

Aim: To evaluate the possible expression of TPO gene in BC.

Materials: Frozen tissue specimens: 8 BC, 5 peri-tumoral breast tissues (PT), 3 pancreatic adenocarcinoma (P), 2 kidney cancers (K) and thyroid (T) as positive control. 3 BC cell-lines (C), MCF-7, T47-D and MDAMB-231, grown with and without β-estradiol and/or insulin-growth-factor-II (IGF-II).

Methods: TPO mRNA expression was evaluated by Reverse-Transcriptase-PCR using different primers pairs distinguishing among different known TPO isoforms. TPO protein expression was studied with Western Blot using monoclonal mouse antibody ab76935.

Results: Known TPO variants mRNA was expressed in all BC and PT, weakly in C independently from β-estradiol and/or IGF-II exposition, at the limit of detection in P and K and highly in T. In particular BC, PT and C presented a new TPO isoform without exons 14 and 16, weakly expressed in T and absent in P and K. TPO protein was found at the expected level (100–110 kDa) in T, C and many BC, PT, P, K; the signal was reduced or disappeared after ab76935 pre-absorption with recombinant TPO fragments, indicating a specific binding. All samples presented also other signals corresponding to lower molecular weight (MW) proteins, present also in T: they could represent corresponding proteins of smaller TPO isoforms.

Conclusions: TPO main isoforms mRNA and protein are weakly but clearly expressed in almost all samples. BC, PT and C present also a new variant without exons 14 and 16, absent in P and K. Further experiments are necessary to quantify TPO expression and to search for a lower MW protein corresponding to the new TPO isoform found.

Declaration of interest: The authors declare that there is no conflict of interest that could be perceived as prejudicing the impartiality of the research project.

Funding: This work was supported, however funding details unavailable.