Molecular characteristics of recurrent triple-negative breast cancer

Due to the fact that the treatment of breast cancer depends significantly on the molecular markers present in the cancer, including estrogen receptor (+), progesterone receptor (+) or erbB2 receptor (+), further investigation targeting triple-negative breast cancer (TNBC) subtypes may assist in elucidating the mechanisms of recurrence of TNBC and enable the identification of novel therapeutic strategies for patients with TNBC. The aim of the present study was to compare the gene expression profiles between TNBC samples that were identified as having recurrent and non-recurrent statuses. Between June 2011 and May 2012, a total of 30 patients with TNBC were examined using a follow-up period of at least 5 years. Their clinicopathological information was retrospectively reviewed and they were classified with a status either of recurrence [n=15 stage II (9), IIIA (2), IIIC (4)] or non-recurrence [n=15 stage II (6), IIIA (1), IIIC (8)]. The total RNA from tissue samples obtained from the recurrent and non-recurrent TNBC patients were used to performed oligonucleotide microarray analysis. The dataset was analyzed using GeneSpring software and validated using reverse transcription-quantitative polymerase chain reaction. Principal component analysis demonstrated that there was a marked difference in the gene expression distribution between the stage IIIc recurrent samples and early stage (stages Ha, IIb and IIIa) recurrent samples. In early stage recurrence, the significant pathway-associated upregulated genes were matrix metalloproteinases (MMPs) and genes associated with cancer cell migration (CDH2) and cell adhesion/motility (KRAS, CDC42, RAC1, ICAM and SRGAP2). By contrast, during stage IIIc recurrence, the significant pathway-associated upregulated genes in the recurrent samples were WNT signaling genes, including WNT 4 and WNT 16. It was concluded that there were markedly different distributions and gene expression profiles between stage IIIc recurrent TNBC tumors and early stage (IIa, IIb, IIIa) recurrent TNBC tumors, which provides important information for the development of effective treatment strategies for TNBC.