Background: Breast cancer is a heterogeneous disease and is the leading cause of cancer-related
deaths among women. Even after diagnosis, the prognosis cannot be concluded since patients can develop resistance
to therapy, which favors tumor growth, invasion and metastasis. In recent years, research has focused on
identifying significant markers that can be used to determine the prognosis. Melatonin can act through G protein–
coupled MT1 receptor, which controls selected protein kinases, influences the levels of transcription factor
phosphorylation, specific genes expression, proliferation, angiogenesis, cell differentiation, migration, and indirectly
controls the transport of glucose in cancer cells. It is known that glucose enters the cells by glucose transporters,
such as GLUT1 which shows wide tissue distribution and appears to be altered in human breast carcinoma.
High GLUT1 expression is associated with increased malignant potential, invasiveness and poor prognosis
in some cancers including breast cancer.
Objective: The aim of this study was to evaluate the expression of MT1 receptor and GLUT1 in breast tumors
and correlate with molecular subtypes and prognostic characteristics.
Method: Protein expression was performed by an immunohistochemical procedure with specific antibodies and
positive and negative controls.
Results: We found that MT1 high expression was associated with good prognosis subtype (Luminal A), while
GLUT1 high expression was related to poor prognosis subtype (triple-negative). In addition, we found high
expression of MT1 in ER+ and the inverse in GLUT1 expression. GLUT1 is also highly expressed in tumor
Conclusion: These results indicate MT1 and GLUT1 as potential targets for breast cancer subtypes and prognosis.