In Vivo Detection of miRNA Expression in Tumors Using an Activatable Nanosensor

Preclinical Imaging Evaluation of miRNAs' Delivery and Effects in Breast Cancer Mouse Models: A Systematic Review

BACKGROUND

We have conducted a systematic review focusing on the advancements in preclinical molecular imaging to study the delivery and therapeutic efficacy of miRNAs in mouse models of breast cancer.

METHODS

A systematic review of English articles published in peer-reviewed journals using PubMed, EMBASE, BIOSIS™ and Scopus was performed. Search terms included breast cancer, mouse, mice, microRNA(s) and miRNA(s).

RESULTS

From a total of 2073 records, our final data extraction was from 114 manuscripts. The most frequently used murine genetic background was Balb/C (46.7%). The most frequently used model was the IV metastatic model (46.8%), which was obtained via intravenous injection (68.9%) in the tail vein. Bioluminescence was the most used frequently used tool (64%), and was used as a surrogate for tumor growth for efficacy treatment or for the evaluation of tumorigenicity in miRNA-transfected cells (29.9%); for tracking, evaluation of engraftment and for response to therapy in metastatic models (50.6%).

CONCLUSIONS

This review provides a systematic and focused analysis of all the information available and related to the imaging protocols with which to test miRNA therapy in an in vivo mice model of breast cancer, and has the purpose of providing an important tool to suggest the best preclinical imaging protocol based on available evidence.

Antisense microRNA185 loaded liposome for efficient inhibition of the hepatic endogenous microRNA185 level

MicroRNA185 (miR185), an endogenous noncoding RNA with 23 nucleotides, is one of key posttranscriptional modulators of cholesterol metabolism in hepatic cells. The antisense inhibitor of miR185 (miR185i) could decrease cholesterol level in vivo, providing a promising agent for anti-atherosclerosis strategy. In this work, a novel LipomiR185i was constructed by thin film hydration method and post-PEGylation as DOPE: DOTAP: Chol: DSPE-PEG₂₀₀₀ at the molar ratio of 1:1:1:0.1 with a nitrogen-to-phosphate ratio of 3, through the optimization of three cationic lipids (DOTAP, DODMA and DLin-MC3-DMA), six helper lipids (PC-98T, HSPC, DOPE, DMPC, DPPC and DSPC), different amounts and incorporation approaches of DSPE-PEG₂₀₀₀ and nitrogen-to-phosphate ratio. LipomiR185i was characterized with a particle size of 174 ± 11 nm, a zeta potential of 7.0 ± 3.3 mV, high encapsulation efficiency and transfection activity. It could protect miR185i from the rapid degradation by nucleases in serum, enhance cellular uptake and promote lysosomal escape in HepG2 cells. LipomiR185i could accumulate in the liver and remain for at least two weeks. More importantly, LipomiR185i significantly down-regulated the hepatic endogenous miR185 level in vitro and in vivo without significant tissue damage at 14 mg⋅kg^-1. The construction of LipomiR185i provides a potential anti-atherosclerotic nanodrug as well as a platform for delivering small RNAs to the liver efficiently and safely.

Peritumoral Microenvironment in High-Grade Gliomas: From FLAIRectomy to Microglia-Glioma Cross-Talk

Cellular composition and molecular signatures of the glioma core compared with infiltrative margins are different, and it is well known that the tumor edge is enriched in microglia. In this review of the literature, we summarize the role of the peritumoral area in high-grade gliomas (HGGs) from surgical and biological points of view. There is evidence on the dual role of microglia in HGGs-a scavenger-tumoricidal role when microglia are activated in an M1 phenotype and a role favoring tumor growth and infiltration/migration when microglia are activated in an M2 phenotype. Microglia polarization is mediated by complex pathways involving cross-talk with glioma cells. In this scenario, extracellular vesicles and their miRNA cargo seem to play a central role. The switch to a specific phenotype correlates with prognosis and the pathological assessment of a specific microglial setting can predict a patient's outcome. Some authors have designed an engineered microglial cell as a biologically active vehicle for the delivery of intraoperative near-infrared fluorescent dye with the aim of helping surgeons detect peritumoral infiltrated areas during resection. Furthermore, the pharmacological modulation of microglia-glioma cross-talk paves the way to more effective therapies.

Combining miR-10b-Targeted Nanotherapy with Low-Dose Doxorubicin Elicits Durable Regressions of Metastatic Breast Cancer

The therapeutic promise of microRNA (miRNA) in cancer has yet to be realized. In this study, we identified and therapeutically exploited a new role for miR-10b at the metastatic site, which links its overexpression to tumor cell viability and proliferation. In the protocol developed, we combined a miR-10b-inhibitory nanodrug with low-dose anthracycline to achieve complete durable regressions of metastatic disease in a murine model of metastatic breast cancer. Mechanistic investigations suggested a potent antiproliferative, proapoptotic effect of the nanodrug in the metastatic cells, potentiated by a cell-cycle arrest produced by administration of the low-dose anthracycline. miR-10b was overexpressed specifically in cells with high metastatic potential, suggesting a role for this miRNA as a metastasis-specific therapeutic target. Taken together, our results implied the existence of pathways that regulate the viability and proliferation of tumor cells only after they have acquired the ability to grow at distant metastatic sites. As illustrated by miR-10b targeting, such metastasis-dependent apoptotic pathways would offer attractive targets for further therapeutic exploration.