GAL3 protein expression is related to clinical features of prolactin-secreting pituitary microadenoma and predicts its recurrence after surgical treatment.

Background: Previous in vitro study showed that Galectin-3 (Gal-3) protein plays an important role in pituitary tumorigenesis, however, the association of Gal-3 expression with the clinical feature and prognosis of pituitary tumor in a clinical setting remains unknown.

Methods: We enrolled 220 patients with prolactin-secreting pituitary adenomas (PA) who previously had transsphenoidal pituitary surgery. The Gal-3 expression was detected in the patients' PA samples using immunohistochemistry and those patients were followed up. A prolactin-secreting PA cell line, the MMQ cell line, was used to study the in vitro effect of Gal-3 on proliferation, migration and invasion of PA cells using small interfering RNA (siRNA) transfecton technique. The in vivo tumorgenesis in nude mice was also studied.

Results: We found that Gal-3 expression was not related to age and sex, but positively associated with tumor invasion (P<0.001), tumor sizes (P<0.001) and pre-operative prolactin levels (P<0.001). The multivariate Cox analysis showed that the Gal-3 expression was closely associated with the recurrence of PA after the surgical treatment (HR =3.15, P=0.002). The in vitro studies showed that Gal-3 knock-down by the siRNA technique significantly inhibited the proliferation, migration and invasion ability of the MMQ cells, whereas Gal-3 siRNA transfection induced apoptosis of the MMQ cells. The in vivo tumorgenesis assay showed that Gal-3 siRNA transfection significantly inhibited the tumor volume in vivo compared to transfection of the control siRNA (P<0.001).

Conclusion: Gal-3 regulates proliferation, apoptosis, migration and invasion of the MMQ cells. Gal-3 may be used as a tissue marker to evaluate the clinical feature and prognosis of PA patients.