Platinum (Pt) drugs are the most potent and commonly used anti-cancer chemotherapeutics. Nanoformulation of Pt drugs has the potential to improve the delivery to tumors and reduce toxic side effects. A major challenge for translating nanodrugs to clinical settings is their rapid clearance by the reticuloendothelial system (RES), hence increasing toxicities on off-target organs and reducing efficacy. We are reporting that an FDA approved parenteral nutrition source, Intralipid 20%, can help this problem. A dichloro (1, 2-diaminocyclohexane) platinum (II)-loaded and hyaluronic acid polymer-coated nanoparticle (DACHPt/HANP) is used in this study. A single dose of Intralipid (2 g/kg, clinical dosage) is administrated [intravenously (i. v.), clinical route] one hour before i.v. injection of DACHPt/HANP. This treatment can significantly reduce the toxicities of DACHPt/HANP in liver, spleen, and, interestingly, kidney. Intralipid can decrease Pt accumulation in the liver, spleen, and kidney by 20.4%, 42.5%, and 31.2% at 24-hr post nanodrug administration, respectively. The bioavailability of DACHPt/HANP increases by 18.7% and 9.4% during the first 5 and 24 hr, respectively.
Growing evidence suggests that Stat3 contributes to chemoresistance. However, the impact of chemotherapy on Stat3 activity is unclear. We found that paclitaxel activated Stat3 in the human lung cancer cell lines PC14PE6AS2 (AS2) and H157, whereas it reduced Stat3 activation in A549 and H460 cells. Pretreatment of AS2 and H157 cells with rotenone, an inhibitor of mitochondrially produced reactive oxygen species (ROS), or carbonyl cyanide p-(trifluoromethoxy)-phenylhydrazone (FCCP), a mitochondrial uncoupler, suppressed the paclitaxel-induced activation of Stat3. Uncoupling protein 2 (UCP-2), located in the inner membrane of the mitochondria, can reduce ROS production in conditions of oxidative stress. UCP-2 protein expression in the four cancer cell lines was higher than that in normal lung epithelial cells (NL-20), but its expression was lower in AS2 and H157 cells relative to A549 and H460 cells. Silencing high UCP-2 expression with small interfering RNA (siRNA) in A549 and H460 cells restored paclitaxel-induced Stat3 activation. In addition, paclitaxel-induced Stat3 activation led to the upregulation of survivin and Mcl-1, which in turn facilitated cell survival. Moreover, the CL1-5 subline had lower UCP-2 expression relative to the parental CL1-0 cells. Treatment with paclitaxel activated Stat3 in CL1-5 but not in CL1-0 cells, whereas in CL1-5 cells, the overexpression of UCP-2 with complementary DNA (cDNA) blocked Stat3 activation. In lung cancer patients, low UCP-2 expression in cancer cells was a predictor of a poor response to chemotherapy. Therefore, UCP-2 modulates the ROS/Stat3 signaling pathway and response to chemotherapy treatment in lung cancer cells. Targeting UCP-2, ROS and Stat3 pathways may improve anticancer therapies.
We have developed a new strategy to temporarily blunt the reticuloendothelial system uptake of nanodrugs, a major challenge for nanodrug delivery and causing off-target toxicities, using an FDA approved nutrition supplement, Intralipid. We have tested our methodology in rats using an experimental platinum-containing anti-cancer nanodrug and three FDA approved nanodrugs, Abraxane, Marqibo, and Onivyde, to determine their toxicities in liver, spleen, and kidney, with and without the addition of Intralipid. Our method illustrates its potentials to deliver nanodrugs with an increase in the bioavailability and a decrease in toxicities. Our study shows that Intralipid treatment exhibits no harmful effect on tumor growing and no negative effect on the anti-tumor efficacy of the platinum-containing nanodrug, as well as animal survival rate in a HT-29 xenograft mouse model. Our methodology could also be a valuable complement/supplement to the “stealth” strategies. Our approach is a general one applicable to any approved and in-development nanodrugs without additional modification of the nanodrugs, thus facilitating its translation to clinical settings.
Chemotherapy may trigger survival signaling in cancer cells and the cells may change the response to chemotherapy. Here we found chemotherapeutics-induced Jak2/Stat3 signaling activation, by which cancer cells escape from death in human lung cancer PC14PE6AS2 (AS2) and H157 cells with constitutively activated Stat3 protein. Cisplatin, paclitaxel and epirubicin are important agents in lung cancer treatment and they are reactive oxygen species (ROS)-producing agents. In AS2 and H157 cells, we found that during the paclitaxel treatment, early Jak2 activation occurred and then Stat3 tyrosine phosphorylation upregulated early. But Stat3 serine phosphorylation was not significantly increased. When AS2 and H157 cells were treated with cisplatin and epirubicin, the Jak2/Stat3 activation was also observed, which can be blocked by AG490. It is indicated that chemotherapy, such as paclitaxel, cisplatin and epirubicin, may activate Jak2/Stat3 pathway. In AS2 cells, chemotherapeutics generated ROS, and the chemotherapy-induced Jak2/Stat3 activation was only effectively inhibited by mitochondrial ROS scavengers as rotenone and antimycin. The similar finding was also observed in H157 cells. It is said that “mild” mitochondrial uncoupling provides a survival benefit in cancer cells. In AS2 and H157 cells, pretreatment with the mitochondrial uncoupler carbonylcyanide-4-trifluoromethoxy-phenylhydrazone (FCCP) inhibited paclitaxel-induced mitochondrial ROS generation, abolished paclitaxel-induced Stat3 activation in AS2 and H157 cells, and augmented paclitaxel-induced mitochondrial membrane potential decrease. Thereafter, we classified AS2 and H157 cells as “FCCP-responsive” or “less mitochondrial uncoupling” cancer cells. So that mitochondrial coupling-mediated oxidative stress modulated paclitaxel-induced Jak2/Stat3 activation in AS2 and H157 cells. Subsequently, Stat3 activation by chemotherapeutics enhanced survivin expression in AS2 and H157 cells. Pretreatment with AG490, FCCP and rotenone blocked paclitaxel-induced survivin expression in a dose-dependent manner. Pretreatment with FCCP and rotenone also made AS2 and H157 cells more sensitive to the drug. Conclusively, anti-cancer drugs-induced Jak2/Stat3 activation confers a survival advantage in lung cancer AS2 and H157 cells via mitochondrial-coupling mediated ROS generation. This is a new phenomenon of cellular response to chemotherapeutics, by which cancer cells escape from drug-induced death. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 1636.
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