Abstract
Innovative cancer treatments, which improve adjuvant therapy and reduce adverse events, are desperately needed. Nanoparticles provide controlled intracellular biomolecule delivery in the absence of activating external cell surface receptors. Prior reports suggest that intracrine signaling, following overexpression of basic fibroblast growth factor (FGF-2) after viral transduction, has a toxic effect on diseased cells. Herein, the research goals were to (1) encapsulate recombinant FGF-2 within stable, alginate-based nanoparticles (ABNs) for non-specific cellular uptake, and (2) determine the effects of ABN-mediated intracellular delivery of FGF-2 on cancer cell proliferation/survival. In culture, human alveolar adenocarcinoma basal epithelial cell line (A549s) and immortalized human bronchial epithelial cell line (HBE1s) internalized ABNs through non-selective endocytosis. Compared to A549s exposed to empty (i.e., blank) ABNs, the intracellular delivery of FGF-2 via ABNs significantly increased the levels of lactate dehydrogenase, indicating that FGF-2-ABN treatment decreased the transformed cell integrity. Noticeably, the nontransformed cells were not significantly affected by FGF-2-loaded ABN treatment. Furthermore, FGF-2-loaded ABNs significantly increased nuclear levels of activated-extracellular signal-regulated kinase ½ (ERK1/2) in A549s but had no significant effect on HBE1 nuclear ERK1/2 expression. Our novel intracellular delivery method of FGF-2 via nanoparticles resulted in increased cancer cell death via increased nuclear ERK1/2 activation.
Highlights
Lung cancer is one of the most prevalent types of carcinoma, resulting in the largest number of cancer-related deaths worldwide [1,2,3]
Isopropanol, calcium chloride (CaCl2), sodium chloride (NaCl), magnesium chloride (MgCl2), Alexa Fluor® 647 Cadaverine, 20x phosphate buffered saline (PBS), 4% paraformaldehyde (PFA) in PBS, Triton® X-100, 4-(2-hydroxyethyl)-1-piperazineethanesulfonic acid (HEPES), glycerol, phenylmethylsulfonyl fluoride (PMSF), sodium orthovanadate (Na3VO4), aprotinin, leupeptin, a bicinchoninic acid assay (BCA) kit, a subcellular protein fractionation kit for cultured cells, BupHTM MES Buffered Saline Packs, Roswell Park Memorial Institute (RPMI) 1640 Medium, and a Pierce lactate dehydrogenase (LDH) Cytotoxicity Assay Kit were purchased from Thermo-Fisher Scientific (Waltham, MA, USA)
This study is the first to report on the intracellular delivery of FGF-2 by alginate-based nanoparticles (ABNs) and its cytotoxic effects on a cancer cell line
Summary
Lung cancer is one of the most prevalent types of carcinoma, resulting in the largest number of cancer-related deaths worldwide [1,2,3]. FGF-2/FGFR interaction promotes receptor dimerization, trans-phosphorylation of tyrosine kinase domains [13,14], and commonly results in increased cancer cell survival, proliferation, drug resistance, and neoangiogenesis [15]. The ERK1/2 pathway is a master regulator of cell fate decisions in eukaryotes ERK1/2-mediated phosphorylation of FGFR2 constitutes a negative feedback loop that regulates FGFR2 expression. In cancer cells, this pathway is broken, and FGFR2 is overexpressed [19]. Inhibition of the FGFR mediated ERK1/2 pathway, using a MEK1/2 inhibitor, increased FGFR2 signaling. Intracellular FGF activity has been investigated as an important target for cancer therapy
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