pH-Responsive Artemisinin Derivatives and Lipid Nanoparticle Formulations Inhibit Growth of Breast Cancer Cells <em>In Vitro</em> and Induce Down-Regulation of HER Family Members

<div><p>Artemisinin (ART) dimers show potent anti-proliferative activities against breast cancer cells. To facilitate their clinical development, novel pH-responsive artemisinin dimers were synthesized for liposomal nanoparticle formulations. A new ART dimer was designed to become increasingly water-soluble as pH declines. The new artemisinin dimer piperazine derivatives (ADPs) remained tightly associated with liposomal nanoparticles (NPs) at neutral pH but were efficiently released at acidic pH's that are known to exist within solid tumors and organelles such as endosomes and lysosomes. ADPs incorporated into nanoparticles down regulated the anti-apoptotic protein, survivin, and cyclin D1 when incubated at low concentrations with breast cancer cell lines. We demonstrate for the first time, for any ART derivative, that ADP NPs can down regulate the oncogenic protein HER2, and its counterpart, HER3 in a HER2+ cell line. We also show that the wild type epidermal growth factor receptor (EGFR or HER1) declines in a triple negative breast cancer (TNBC) cell line in response to ADP NPs. The declines in these proteins are achieved at concentrations of NP109 at or below 1 µM. Furthermore, the new artemisinin derivatives showed improved cell-proliferation inhibition effects compared to known dimer derivatives.</p> </div

Summary of IC₅₀ values calculated from MTT assays of ADPs and NPs on BT474 and MDA-MB-231 cells.

<p>Values represent average (±SD) calculated from three independent experiments. *Exceeded maximum concentration of assay.</p

Summary of loading and release efficiencies of the NPs.

<p>Values represent an average and standard deviation of three independent experiments read at λ = 263 nm.</p

Effects of NP109 on the expression of selected proteins involved in cell proliferation, cell cycling, and apoptosis in BT474 (a–c) and MDA-MB-231 cells (d–f).

<p>Effects of NP109 on the expression of selected proteins involved in cell proliferation, cell cycling, and apoptosis in BT474 (a–c) and MDA-MB-231 cells (d–f).</p

Structures of artemisinin dimer succinate, ADPs 106–109 and ADPm109 the monomer analogue of compound ADP109.

<p>Structures of artemisinin dimer succinate, ADPs 106–109 and ADPm109 the monomer analogue of compound ADP109.</p