A pilot study on plasma levels of micro-RNAs involved in angiogenesis and vascular maturation in patients with breast cancer.

Micro-RNAs (miRNAs) have a complex role in carcinogenesis and tumour progression. Several miRNAs, such as miR-221, miR-27b and miR-132, have been implicated in the regulation of VEGF tumour angiogenic activity. In this pilot study, we assessed angiogenesis and DLL4+ vascular maturation index (VMI) in breast cancer tissues, in parallel with the plasma levels of the above-mentioned miRNAs. Significantly higher than control samples pre-operative levels were recorded in 10/11, 7/11 and 9/11 cases for the miR-221, miR-27b and miR-132, respectively. Seven days after surgery, a significant reduction of these miRNAs was noted in 6/11, 3/11 and 2/11 cases, respectively. High pre-operative levels of miR-27b were linked with node metastasis (p = 0.04). High pre-operative levels of miR-132 were linked with small tumours (p = 0.03) and her2 overexpression (p = 0.003). The DLL4+ VMI ranged from 26 to 69% (median 45%). Patients with poor DLL4+ VMI had significantly high pre-operative and post-operative levels of miR-221 (p = 0.01 and 0.02, respectively) and high post-operative levels of miR-132 (p = 0.02). It is concluded that angiogenesis-related miRs as detected in the plasma of patients may prove of a useful tool in the identification of patients with poor vascular maturation and high risk to develop metastasis. Whether such miRs may identify patients who would benefit from vascular normalization policies is a hypothesis that emerges from the current study.