Can recurrences be predicted in craniopharyngiomas? β-catenin coexisting with stem cells markers and p-ATM in a clinicopathologic study of 45cases.

BACKGROUND: Recurrence is a common feature of craniopharyngiomas, benign tumors that origin from squamous epithelial remnants of Rathke's pouch- arising at any segment of its whole course. There are two histotypes, showing different morphology and clinical behavior: adamantinomatous(adaCP) and papillary (papCP). An univocal strategy of management has not yet been defined, being considered the combination of surgery and radiotherapy the most effective, especially in case of incomplete resection. Therefore, the identification of factors influencing the biological and clinical behaviour is of paramount importance. β-catenin is a cell-cell adhesion protein, whose nuclear localization has been linked to the pathogenesis of adaCP: its nuclear accumulation is associated to the presence of a tumor stem cell subpopulation. The latter is made of cells capable of self-renewal, hence believed to be responsible of recurrence, metastases and resistance to therapy in all tumors. ATM is a kinase activated by autophosphorylation (p-ATM) upon DNA double-strand breaks. It is involved not only in DNA repair, but also in tumor migration and invasiveness. Its expression may have prognostic implications in many neoplastic diseases.

METHODS: In this study, we measured the immunohistochemical expression of β-catenin, stem cell markers (CD133, CD166), Ki67 and pATMin 45 craniopharyngiomas and correlated it with clinicopathologic features.

RESULTS: Statistical analysis revealed strong correlation of β-catenin with recurrence (p = 0.0039), Ki67 (p = 0.0011, r = 0.4903) and CD166 (p = 0.0002, r = 0.6218). A slight tendency to a higher expression of β-catenin was recorded for adaCP rather than papCP (p = 0.0895).Fisher's exact test showed that CD166 was significantlyrelated with recurrence (p = 0.0040). Furthermore, cytoplasmic pATM was more expressed in adaCPs (p = 0.0470), compared to papCPs that displayed a more evident nuclear signal (p = 0.0313) instead.

CONCLUSIONS: Backing upon these data, we could weigh in on the need of identifying β-catenin and CD166 as prognostic markersthat could be useful in predicting thebiologicalbehavior, as recurrence risk incraniopharyngiomas. The final goal is to drew up a prognostic algorithm to be of aid in the planning of an appropriate treatment strategy. Furthermore, our findings demonstrate that pATM could be used as additional distinction-marker between the two histotypes.