Abstract
Background5-Fluorouracil (5-FU) has been commonly prescribed for patients with colorectal cancer (CRC), but resistance to 5-FU is one of the main reasons for failure in CRC. Recently, microRNAs (miRNAs) have been established as a means of reversing the dilemma by regulating signaling pathways involved in initiation and progression of CRC. However, how to safely and effectively deliver miRNA to target cells becomes a main challenge.ResultsIn this study, Engineered exosomes were exploited to simultaneously deliver an anticancer drug 5-FU and miR-21 inhibitor oligonucleotide (miR-21i) to Her2 expressing cancer cells. Purified engineered exosomes from the donor cells loaded with 5-FU and miR-21i via electroporation to introduce into 5-FU-resistant colorectal cancer cell line HCT-1165FR. Furthermore, systematic administration of 5-FU and miR-21i loaded exosomes in tumor bearing mice indicated a significantly anti-tumor effect. The results showed that the engineered exosome-based 5-FU and miR-21i co-delivery system could efficiently facilitate cellular uptake and significantly down-regulate miR-21 expression in 5-FU resistant HCT-1165FR cell lines. Consequently, the down-regulation of miR-21 induced cell cycle arrest, reduced tumor proliferation, increased apoptosis and rescued PTEN and hMSH2 expressions, regulatory targets of miR-21. Of particular importance was the significant reduction in tumor growth in a mouse model of colon cancer with systematic administration of the targeting miR-21i. More excitedly, the combinational delivery of miR-21i and 5-FU with the engineered exosomes effectively reverse drug resistance and significantly enhanced the cytotoxicity in 5-FU-resistant colon cancer cells, compared with the single treatment with either miR-21i or 5-FU.ConclusionThe strategy for co-delivering the functional small RNA and anticancer drug by exosomes foreshadows a potential approach to reverse the drug resistance in CRC and thus to enhance the efficacy of the cancer treatment.
Highlights
Colorectal carcinoma (CRC) is the third most lethal cancer worldwide, and shows a higher morbidity because of its aggressive behavior, poor prognosis, and lack of targeted treatments [1]. 5-FU based chemotherapy plays an important role in treatment of CRC
Isolation and characterization of exosomes To confer targeting capabilities, we fused human epidermal growth factor receptor 2 (Her2)-binding affibody to the extra-exosomal N terminus of human Lamp2, a protein found abundantly in exosomal membranes according to the previous research [25], and cloned into pLVX-GFP-N1, so the final fusion protein consist of Her2-binding affibody, LAMP2 and GFP, named THLG
Fluorescence microscope of THLG-293T or LG-293T cells showed that THLG and LG chimera proteins were located in the granule membranes as well as in the plasma membranes (Fig. 1b).The exosomes were purified from the culture supernatants of THLG-293T or LG-293T cells by ultracentrifugation, and the markers of exosomes, such as CD63, CD9 and CD81 were determined by western (Fig. 1c)
Summary
Colorectal carcinoma (CRC) is the third most lethal cancer worldwide, and shows a higher morbidity because of its aggressive behavior, poor prognosis, and lack of targeted treatments [1]. 5-FU based chemotherapy plays an important role in treatment of CRC. Liang et al J Nanobiotechnol (2020) 18:10 administration of 5-FU Many mechanisms such as gene mutation, DNA methylation and histone modification are involved in the resistance of cancer cells to chemotherapeutic agents [2,3,4]. Many efforts have been exerted in analyzing the role of miRNAs in the development of drug resistance in a variety of cancers, which have shown that chemoresistant cancer cells and their parental chemosensitive ones have distinct miRNA expression patterns, and the molecular targets and mechanisms of chemoresistance have been elucidated [5, 6]. We speculate that the co-delivery of MDR-reversing miRNA and chemotherapeutics will be a promising way to overcome MDR in cancer chemotherapy [11, 12]. A safe and efficient targeted delivery system is pivotal for CRC therapy
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