Potent therapeutic activity of folate receptor-targeted liposomal carboplatin in the localized treatment of intraperitoneally grown human ovarian tumor xenograft

Intraperitoneal (IP) therapy with platinum (Pt)-based drugs has shown promising results clinically; however, high locoregional concentration of the drug could lead to adverse side effects. In this study, IP administration was coupled with a folate receptor-targeted (FRT) liposomal system, in an attempt to achieve intracellular delivery of the Pt-based drug carboplatin in order to increase therapeutic efficacy and to minimize toxicity. In vitro and in vivo activity of FRT carboplatin liposomes was compared with the activity of free drug and nontargeted (NT) carboplatin liposomes using FR-overexpressing IGROV-1 ovarian cancer cells as the model. Significant reduction in cell viability was observed with FRT liposomes, which, compared with the free drug, provided an approximately twofold increase in carboplatin potency. The increase in drug potency was correlated with significantly higher cellular accumulation of Pt resulting from FRT liposomal delivery. Further evaluation was conducted in mice bearing intraperitoneally inoculated IGROV-1 ovarian tumor xenografts. A superior survival rate (five out of six animals) was achieved in animals treated with FRT carboplatin liposomes, injected intraperitoneally with a dose of 15 mg/kg and following a schedule of twice-weekly administration for 3 weeks. In contrast, no survivors were observed in the free drug or NT carboplatin liposome groups. The presence of cancer cells in lung and liver tissues was observed in the saline, free carboplatin, and NT carboplatin liposome groups. However, there was no sign of cancer cells or drug-related toxicity detected in tissues from the animals treated with FRT carboplatin liposomes. The results of this study have demonstrated for the first time that the approach of coupling IP administration with FRT liposomal delivery could provide significantly improved therapeutic efficacy of carboplatin in the treatment of metastatic ovarian cancer

Intrinsic Xenobiotic Resistance of the Intestinal Stem Cell Niche

The gut absorbs dietary nutrients and provides a barrier to xenobiotics and microbiome metabolites. To cope with toxin exposures, the intestinal epithelium is one of the most rapidly proliferating tissues in the body. The stem cell niche supplies essential signaling factors including Wnt proteins secreted by subepithelial myofibroblasts. Unexpectedly, therapeutically effective doses of orally administered PORCN inhibitors that block all Wnt secretion do not affect intestinal homeostasis. We find that intestinal myofibroblasts are intrinsically resistant to multiple xenobiotics, including PORCN inhibitors and the anthracycline antibiotic doxorubicin. These myofibroblasts have high expression of a subset of drug transporters; knockout of Mrp1/Abcc1 enhances drug sensitivity. Tamoxifen administration to Rosa26CreERT2;mT/mG mice visually highlights the drug-resistant intestinal stromal compartment and identifies small populations of drug-resistant cells in lung, kidney, and pancreatic islets. Xenobiotic resistance of the Wnt-producing myofibroblasts can protect the intestinal stem cell niche in the face of an unpredictable environment

PDGFR alpha(+) pericryptal stromal cells are the critical source of Wnts and RSPO3 for murine intestinal stem cells in vivo

10.1073/pnas.1713510115PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA11514E3173-E318