Serum MALAT1 expression predicts clinical outcome in breast cancer patients receiving cyclophosphamide based treatment

Cyclophosphamide based treatment is one of the most common used chemotherapeutic strategies in breast cancer, however large proportion of patients finally become chemoresistant. The metastasis-associated lung adenocarcinoma transcript 1 (MALAT1) is known to be associated with metastasis and is a favorable prognostic factor for lung cancer. Whether MALAT1 plays a critical role in chemoresistance in breast cancer remains unclear. In this study, we found that MALAT1 was significantly upregulated in breast cancer specimens and associated with tumor size, lymph node status, estrogen receptor expression (ER) and TNM stage. By using the RT-qPCR directly applied in serum (RT-qPCR-D) method, we revealed the diagnostic and prognostic value of serum MALAT1 in breast cancer patients. Moreover, serum MALAT1 was significantly up-regulated in patients non-responding to cyclophosphamide treatment compared with responding patients, and the proportion of patients who not responding to chemotherapy was significantly higher in the high MALAT1 expressing group than in the low group. Finally, the Kaplan-Meier survival data showed that serum MALAT1 is an independent prognostic factor for chemoresponse to cyclophosphamide therapy among breast cancer patients. To conclude, our study indicates that high level of circulating MALAT1 expression was correlated with enhanced malignant potential and poor prognosis of breast cancer patients. Furthermore, high serum MALAT1 was associated with poor response to cyclophosphamide based chemotherapy in breast cancer patients. Thus, suppression of MALAT1 could be a future direction to enhance chemosensitivity to cyclophosphamide based chemotherapy regimens.