![Sample our Medicine, Dentistry, Nursing & Allied Health journals, sign in here to start your FREE access for 14 days]({"type":"image" , "src" : "/sda/5944/TOC-Subject-Sample-2021-Medicine-Dentistry-Nursing-Allied-Health.jpg"})
Abstract
Objectives: All-trans retinoic acid (ATRA) is one of the most successful examples of differentiation agents and histone deacetylase inhibitors, such as tributyrin (TB), are known for their antitumor activity and potentiating action of drugs, such as ATRA. Nanostructured lipid carriers (NLC) represent a promising alternative to the encapsulation of lipophilic drugs such as ATRA. This study aims to develop, characterize and evaluate the cytotoxicity of ATRA–TB-loaded NLC for cancer treatment. Methods: The influence of in situ formation of an ion pairing between ATRA and a lipophilic amine (benethamine) on the characteristics of NLC (size, zeta potential, encapsulation efficiency) was evaluated. TB, a butyric acid donor, was used as a component of the lipid matrix. In vitro activity on cell viability and distribution of cell cycle phases were evaluated for MCF-7, MDA-MB-231, HL-60 and Jurkat cell lines. Results: The presence of the amine significantly increased the encapsulation efficiency of ATRA in NLC. Inhibition of cell viability by TB–ATRA-loaded NLC was more pronounced than the free drug. Analysis of the distribution of cell cycle phases also showed increased activity for TB–ATRA-loaded NLC, with the clear effect of cell cycle arrest in G0/G1 phase transition. The presence of TB played an important role in the activity of the formulation. Conclusion: Taken together, these findings suggest that TB–ATRA-loaded NLC represents a promising alternative to intravenous administration of ATRA in cancer treatment.
Acknowledgements
The authors wish to thank G Hawes, M.Ed. English Education, University of Georgia, USA, for editing this manuscript.
Financial & competing interests disclosure
This study was supported by NIH Grant 1R03TW008709 and by grants from Minas Gerais State Agency for Research and Development (FAPEMIG, Brazil) and by the Brazilian agencies CAPES and CNPq. The authors have no other relevant affiliations or financial involvement with any organization or entity with a financial interest in or financial conflict with the subject matter or materials discussed in the manuscript apart from those disclosed.
No writing assistance was utilized in the production of this manuscript.
This study aimed to develop and evaluate the in vitro cytotoxic activity of nanostructured lipid carriers (NLC) loaded with all-trans retinoic acid (ATRA) and tributyrin (TB). TB is a histone deacetylase inhibitor known for its antitumor activity and potentiating action of drugs such as ATRA.
The lipophilic amine BNT promoted a significant increase of encapsulation for ATRA in NLC.
Cytotoxic effects against four important tumor cell lines were evaluated. A clear advantage was observed when ATRA-loaded NLC was compared with free ATRA for the MCF-7, MDA-MB-231, HL-60 and Jurkat cell lines.
For ATRA-resistant cells such as MDA-MB-231 and Jurkat cells, it was suggested that the activity of ATRA-loaded NLC results from the release of butyric acid from TB hydrolysis.
The effects of treatments in MDA-MB-231 with ATRA-loaded NLC are probably related to some degree of aneuploidy (DNA content different from 2n).
Flow cytometry assay was employed as a quantitative measure of subdiploid DNA content and phases of the cell cycle. ATRA-loaded NLC showed a significant accumulation in the G0/G1 phase when compared with free ATRA for all cell lines.
None of the treatments induced significant cell death, with values of subdiploid DNA content less than 1%. These findings are not unexpected, once ATRA-induced cell cycle arrest in the G0/G1 phase is usually followed by differentiation and/or apoptosis.
A remarkable increase in anticancer activity of ATRA–TB-loaded NLC in comparison with free ATRA was obtained against leukemic cells using a formulation with high drug encapsulation.