Incidence rates of breast cancer have been increasing in every country with significant higher proportion of cancer-related mortality particularly in low- and middle-income countries including in Indonesia. Developing novel biomarker is an emerging field in the breast cancer study. Application of a promising minimally-invasive biomarker, circulating microRNA, for additional improvement of diagnosis and therapeutic monitoring in breast cancer is not fully understood.
We analysed expression of circulating miR-155 in 102 breast cancer patients at diagnosis and after treatment as well as 15 healthy women. Total RNA was extracted from patient’s plasma and microRNA expression was measured using quantitative reverse transcription polymerase chain reaction (qRT-PCR). The expression levels of circulating miR-155 were compared according to the effect of treatment, clinicopathological variables, and progression-free survival.
In comparison to the healthy women, expression of circulating miR-155 levels were significantly higher (medians were 18.49±19 and 1.28±0.18, respectively; p < 0.0001). The expression levels of miR-155 were significantly reduced after patients completed surgery and chemotherapy (medians were 18.49±19 at diagnosis and 1.32±0.22 after treatment, respectively; p < 0.0001). Patients older than 40 years old expressed higher circulating miR-155 than those younger than 40 years-old (medians were 28.92±22 and 4.19±2.49, respectively; p < 0.0001). No significant different miR-155 expression levels at diagnosis were observed across tumor grades, sizes, subtypes, and clinical stages. Although patients with circulating miR-155 upregulation have longer progression-free survivals, the difference was not statistically significant compared to those without upregulation. (median survivals were 55 vs 43 weeks and Mantel-Cox test p = 0.7).
Expression of circulating miR-155 expression was significantly elevated in breast cancer patients and was decreased after treatment. Therefore, circulating miR-155 was potentially applicable as diagnostic and therapeutic monitoring marker in breast cancer.
Clinical trial identification
Legal entity responsible for the study
Universities Gadjah Mada.
The Ministry of Research and Higher Education - Republic of Indonesia (PTUPT 1818/UNI/DITLIT/LT/2018 and PPUPT 1987/UNI/DITLIT/LT/2018).
All authors have declared no conflicts of interest.