Expression of the GLUT1 Glucose Transporter in Adenoid Cystic Carcinomas Transformed into Adenocarcinoma or Undifferentiated Carcinoma
A Altemani, VL Bonfitto, AP Demasi, AF Costa, JF Bonfitto, VC Araujo. University of Campinas (UNICAMP), Campinas, São Paulo, Brazil; CPO São Leopoldo Mandic, Campinas, São Paulo, Brazil
Background: In neoplasia, enhanced expression of GLUT1 has been interpreted as increased glucose uptake as well as response to tissue hypoxia. The latter has been implicated in the pathogenesis of dedifferentiated phenotype in certain types of cancer. GLUT1 expression has also been reported to correlate with poor prognosis, tumor aggressiveness and lymph node metastases. Transformation of adenoid cystic carcinoma to adenocarcinoma or undifferentiated carcinoma (ACC-Ad/UC) has been linked to accelerated clinical course and high propensity for lymph node metastases. In order to analyze whether a) hypoxia could be involved in the pathogenesis of ACC-Ad/UC and b) GLUT1 expression could be used as a predictor of clinical outcome, we looked at the expression of this marker in conventional and transformed areas of ACC-Ad/UC.
Design: In six cases of ACC-Ad/UC and in 18 ordinary ACC the immunohistochemical expression of GLUT1 was assessed using a three-tiered scale: >10% - 25%, and > 25- 50% and >50% of positive cells. α-SMA was used for detection of myoepithelial cells and the proliferation index was evaluated by Ki-67. Demographic and clinical information was obtained from the patients' medical records.
Results: The transformed areas were classified according to histological patterns as adenocarcinoma in 4 cases and solid undifferentiated carcinoma in 2. Loss of myoepithelial layer was found only in the transformed component, which also showed higher Ki-67 index. In ACC-Ad/UC, only one patient died of disease and presented lymph node metastases. Three did not show recurrence (median follow-up 54 months), including one long-term survivor (131 months). Both conventional areas of ACC-Ad/UC and ordinary ACC were negative for GLUT1 in most cases (83.3% and 81.3%, respectively), whereas the Ad/UC component presented increased expression of GLUT1+ in 50% of cases. However, the degree of GLUT1 expression correlated neither with clinical outcome nor with the histological subtype of the transformed component.
Conclusions: The scanty expression of GLUT1 in conventional areas of ACC-Ad\UC as well as in ordinary ACC suggests that hypoxia may not play a crucial role in the development of the Ad/UC phenotype. The enhanced metabolic demand leading to increased glucose uptake could explain higher GLUT1 expression in the Ad/UC areas, but GLUT1 cannot be considered useful as prognostic marker.
Category: Head & Neck
Wednesday, March 24, 2010 9:30 AM
Poster Session V # 156, Wednesday Morning