Suicide HSVtk Gene Delivery by Neurotensin-Polyplex Nanoparticles via the Bloodstream and GCV Treatment Specifically Inhibit the Growth of Human MDA-MB-231 Triple Negative Breast Cancer Tumors Xenografted in Athymic Mice

Abstract

The human breast adenocarcinoma cell line MDA-MB-231 has the triple-negative breast cancer (TNBC) phenotype, which is an aggressive subtype with no specific treatment. MDA-MB-231 cells express neurotensin receptor type 1 (NTSR1), which makes these cells an attractive target of therapeutic genes that are delivered by the neurotensin (NTS)-polyplex nanocarrier via the bloodstream. We addressed the relevance of this strategy for TNBC treatment using NTS-polyplex nanoparticles harboring the herpes simplex virus thymidine kinase (HSVtk) suicide gene and its complementary prodrug ganciclovir (GCV). The reporter gene encoding green fluorescent protein (GFP) was used as a control. NTS-polyplex successfully transfected both genes in cultured MDA-MB-231 cells. The transfection was demonstrated pharmacologically to be dependent on activation of NTSR1. The expression of HSVtk gene decreased cell viability by 49% (P<0.0001) and induced apoptosis in cultured MDA-MB-231 cells after complementary GCV treatment. In the MDA-MB-231 xenograft model, NTS-polyplex nanoparticles carrying either the HSVtk gene or GFP gene were injected into the tumors or via the bloodstream. Both routes of administration allowed the NTS-polyplex nanoparticles to reach and transfect tumorous cells. HSVtk expression and GCV led to apoptosis, as shown by the presence of cleaved caspase-3 and Apostain immunoreactivity, and significantly inhibited the tumor growth (55–60%) (P<0.001). At the end of the experiment, the weight of tumors transfected with the HSVtk gene was 55% less than that of control tumors (P<0.05). The intravenous transfection did not induce apoptosis in peripheral organs. Our results offer a promising gene therapy for TNBC using the NTS-polyplex nanocarrier.

Transient transfection of human CDNF gene reduces the 6-hydroxydopamine-induced neuroinflammation in the rat substantia nigra

“…The NTS-polyplexes were made by electrostatically binding the mutant Vp1 SV40 KP (MAPTKRKGSCPGAAPNKPK; 90% purity; SynPep Corp., Dublin, CA, USA) to pDNA [ 45 , 47 , 52 ]. Retardation and retention gel assays were used to determine and calculate the optimal molar ratio of polyplex components as described in detail elsewhere [ 45 , 47 , 48 , 52 , 53 ]. Accordingly, the final optimum molar ratio of NTS-polyplex components for all the plasmids used were 30 nM pDNA: 36 μM KP: 900 nM NTS-carrier and, at this molar ratio, the concentration of NTS used was 385.6 pmol/μL, calculated as per 125 I-NTS [ 47 , 50 ].…”

The role of Neurotensin and its receptors in non-gastrointestinal cancers: a review

“…The same team also showed that NTSR1 was involved in cellular migration, invasion and induction of matrix metalloproteases-9 (MMP-9) and use of SR48692 (an NTSR1 antagonist) halted tumor growth in triple-negative cancer cells (MDA-MB-231) xenografted in nude mice [38]. Subsequent studies in triple-negative breast cancer phenotype cells (MDA-MB-231) which were xenografted in nude female mice, and were treated with both intravenous and intratumoral NT polyplex nanoparticles harboring the herpes simplex virus thymidine kinase suicide gene and ganciclovir, showed a significant growth inhibition (55-60%) (p < 0.001) [39].…”

Dual-Targeting Nanoparticles for In Vivo Delivery of Suicide Genes to Chemotherapy-Resistant Ovarian Cancer Cells

“…During the therapeutic portion of this study, multiple (n= 8) IP injections of particles were administered due to the relatively low DNA loading into the c-CPE-NP (3.37±0.75μg/mg particles; figure 2B and Supplementary table 3). This strategy allowed for the delivery of a total dose of DNA to the tumor that has been previously described to be in the therapeutic range in gene therapy studies (between 50 and 100μg)(37, 38). …”