PMID- 24516610 OWN - NLM STAT- MEDLINE DCOM- 20150113 LR - 20211021 IS - 1932-6203 (Electronic) IS - 1932-6203 (Linking) VI - 9 IP - 2 DP - 2014 TI - Exosome release and low pH belong to a framework of resistance of human melanoma cells to cisplatin. PG - e88193 LID - 10.1371/journal.pone.0088193 [doi] LID - e88193 AB - Intrinsic resistance to cytotoxic drugs has been a main issue in cancer therapy for decades. Microenvironmental acidity is a simple while highly efficient mechanism of chemoresistance, exploited through impairment of drug delivery. The latter is achieved by extracellular protonation and/or sequestration into acidic vesicles. This study investigates the importance of extracellular acidosis and nanovesicle (exosome) release in the resistance of human tumour cell to cisplatin (CisPt); in parallel to proton pump inhibitors (PPI) ability of interfering with these tumour cell features. The results showed that CisPt uptake by human tumour cells was markedly impaired by low pH conditions. Moreover, exosomes purified from supernatants of these cell cultures contained various amounts of CisPt, which correlated to the pH conditions of the culture medium. HPLC-Q-ICP-MS analysis revealed that exosome purified from tumour cell culture supernatants contained CisPt in its native form. PPI pre-treatment increased cellular uptake of CisPt, as compared to untreated cells, in an acidic-depend manner. Furthermore, it induced a clear inhibition of exosome release by tumour cells. Human tumours obtained from xenografts pretreated with PPI contained more CisPt as compared to tumours from xenografts treated with CisPt alone. Further analysis showed that in vivo PPI treatment induced a clear reduction in the plasmatic levels of tumour-derived exosomes which also contained lower level of CisPt. Altogether, these findings point to the identification of a double mechanism that human malignant melanoma use in resisting to a dreadful cellular poison such as cisplatin. This framework of resistance includes both low pH-dependent extracellular sequestration and an exosome-mediated elimination. Both mechanisms are markedly impaired by proton pump inhibition, leading to an increased CisPt-dependent cytotoxicity. FAU - Federici, Cristina AU - Federici C AD - Department of Therapeutic Research and Medicine Evaluation, National Institute of Health, Rome, Italy. FAU - Petrucci, Francesco AU - Petrucci F AD - Department of Environment and Primary Prevention, National Institute of Health, Rome, Italy. FAU - Caimi, Stefano AU - Caimi S AD - Department of Environment and Primary Prevention, National Institute of Health, Rome, Italy. FAU - Cesolini, Albino AU - Cesolini A AD - Department of Ematology, Oncology and Molecular Biology, National Institute of Health, Rome, Italy. FAU - Logozzi, Mariantonia AU - Logozzi M AD - Department of Therapeutic Research and Medicine Evaluation, National Institute of Health, Rome, Italy. FAU - Borghi, Martina AU - Borghi M AD - Department of Therapeutic Research and Medicine Evaluation, National Institute of Health, Rome, Italy. FAU - D'Ilio, Sonia AU - D'Ilio S AD - National Centre for Chemicals Substances, National Institute of Health, Rome, Italy. FAU - Lugini, Luana AU - Lugini L AD - Department of Therapeutic Research and Medicine Evaluation, National Institute of Health, Rome, Italy. FAU - Violante, Nicola AU - Violante N AD - Department of Environment and Primary Prevention, National Institute of Health, Rome, Italy. FAU - Azzarito, Tommaso AU - Azzarito T AD - Department of Therapeutic Research and Medicine Evaluation, National Institute of Health, Rome, Italy. FAU - Majorani, Costanza AU - Majorani C AD - Department of Environment and Primary Prevention, National Institute of Health, Rome, Italy. FAU - Brambilla, Daria AU - Brambilla D AD - Department of Therapeutic Research and Medicine Evaluation, National Institute of Health, Rome, Italy. FAU - Fais, Stefano AU - Fais S AD - Department of Therapeutic Research and Medicine Evaluation, National Institute of Health, Rome, Italy. LA - eng PT - Journal Article DEP - 20140206 PL - United States TA - PLoS One JT - PloS one JID - 101285081 RN - 0 (Buffers) RN - 0 (Proton Pump Inhibitors) RN - 0 (Solutions) RN - Q20Q21Q62J (Cisplatin) SB - IM MH - Animals MH - Buffers MH - Cell Death/drug effects MH - Cell Line, Tumor MH - Cellular Microenvironment/drug effects MH - Chromatography, High Pressure Liquid MH - Cisplatin/*pharmacology MH - Drug Resistance, Neoplasm/*drug effects MH - Exosomes/drug effects/*metabolism MH - Extracellular Space/drug effects/metabolism MH - Female MH - Humans MH - Hydrogen-Ion Concentration/drug effects MH - Intracellular Space/drug effects/metabolism MH - Melanoma/*pathology MH - Mice, SCID MH - Proton Pump Inhibitors/pharmacology MH - Reference Standards MH - Solutions MH - Spectrophotometry, Atomic MH - Xenograft Model Antitumor Assays PMC - PMC3916404 COIS- Competing Interests: Stefano Fais has read the journal's policy and the authors have the following conflicts: Patent: A NEW METHOD TO MEASURE AND CHARACTERIZE MICROVESICLES IN THE HUMAN BODY FLUIDS, PCT/EE2009/000001 for the ExoTest described in this work by Hansabiomed Estonia. Inventors: Stefano Fais and Mariantonia Logozzi confirm that their patent (A new method to measure and characterize microvesicles in the human body fluids, PCT/EE2009/000001) doesn't alter the adherence to all the PLOS ONE policies on sharing data and materials, as detailed online in the guide. EDAT- 2014/02/12 06:00 MHDA- 2015/01/15 06:00 PMCR- 2014/02/06 CRDT- 2014/02/12 06:00 PHST- 2013/09/27 00:00 [received] PHST- 2014/01/05 00:00 [accepted] PHST- 2014/02/12 06:00 [entrez] PHST- 2014/02/12 06:00 [pubmed] PHST- 2015/01/15 06:00 [medline] PHST- 2014/02/06 00:00 [pmc-release] AID - PONE-D-13-42730 [pii] AID - 10.1371/journal.pone.0088193 [doi] PST - epublish SO - PLoS One. 2014 Feb 6;9(2):e88193. doi: 10.1371/journal.pone.0088193. eCollection 2014.