title: Molecular mechanisms of patupilone resistance.
abstract: Patupilone is an epothilone in advanced clinical development that has shown promising efficacy in heavily pretreated patients. This study aimed at characterizing the mechanisms of patupilone activity in resistant patients. To this end, we generated patupilone-resistant cells using two cellular models, the first characterized by high chemosensitivity and low class III beta-tubulin (TUBB3) expression (A2780), and the second by low chemosensitivity and high TUBB3 expression (OVCAR-3). The obtained cell lines were named EPO3 and OVCAR-EPO, respectively. The same selection procedure was done in A2780 cells to generate a paclitaxel-resistant cell line (TAX50). Factors of resistance are expected to increase in the drug-resistant cell lines, whereas factors of drug sensitivity will be down-regulated. Using this approach, we found up-regulation of TUBB3 in TAX50, but not EPO3, cells, showing that TUBB3 mediates the resistance to paclitaxel but not to patupilone. Moreover, TUBB3 was a factor of patupilone sensitivity because OVCAR-EPO cells exhibited a dramatic reduction of TUBB3 and a concomitant sensitization to hypoxia and cisplatin-based chemotherapy. To identify the mechanisms underlying patupilone resistance, tubulin genes were sequenced, thereby revealing that a prominent mechanism of drug resistance is represented by point mutations in class I beta-tubulin. Overall, these results suggest that paclitaxel and patupilone have nonoverlapping mechanisms of resistance, thus allowing the use of patupilone for those patients relapsing after paclitaxel-based chemotherapy. Furthermore, patupilone represents a promising first-line option for the treatment of high-risk ovarian cancer patients, who exhibit high TUBB3 levels and poor response to standard paclitaxel-platin chemotherapy.
authors.affiliation: Department of Obstetrics and Gynecology, Laboratory of Antineoplastic Pharmacology, Catholic University of the Sacred Heart, Rome, Italy.
authors.forename: Simona
authors.initials: S
authors.lastname: Mozzetti
authors.forename: Raffaella
authors.initials: R
authors.lastname: Iantomasi
authors.forename: Ilaria
authors.initials: I
authors.lastname: De Maria
authors.forename: Silvia
authors.initials: S
authors.lastname: Prislei
authors.forename: Marisa
authors.initials: M
authors.lastname: Mariani
authors.forename: Alessia
authors.initials: A
authors.lastname: Camperchioli
authors.forename: Silvia
authors.initials: S
authors.lastname: Bartollino
authors.forename: Daniela
authors.initials: D
authors.lastname: Gallo
authors.forename: Giovanni
authors.initials: G
authors.lastname: Scambia
authors.forename: Cristiano
authors.initials: C
authors.lastname: Ferlini
mesh_terms: D018435:ATP Binding Cassette Transporter, Subfamily B; D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1 / Q000096:biosynthesis / Q000378:metabolism; D000070997:ATP Binding Cassette Transporter, Subfamily G, Member 2; D018528:ATP-Binding Cassette Transporters / Q000096:biosynthesis / Q000378:metabolism; D000970:Antineoplastic Agents / Q000494:pharmacology; D015687:Cell Hypoxia / Q000502:physiology; D045744:Cell Line, Tumor; D019008:Drug Resistance, Neoplasm; D034261:Epothilones / Q000494:pharmacology*; D005260:Female; D006801:Humans; D027425:ATP-Binding Cassette, Sub-Family C Proteins / Q000096:biosynthesis / Q000378:metabolism; D009363:Neoplasm Proteins / Q000096:biosynthesis / Q000378:metabolism; D010051:Ovarian Neoplasms / Q000188:drug therapy* / Q000235:genetics / Q000378:metabolism; D017239:Paclitaxel / Q000494:pharmacology; D017354:Point Mutation; D020033:Protein Isoforms; D012333:RNA, Messenger / Q000096:biosynthesis / Q000235:genetics; D014404:Tubulin / Q000096:biosynthesis / Q000235:genetics; D015854:Up-Regulation
chemical_list: D018435:ATP Binding Cassette Transporter, Subfamily B; D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1; D000070997:ATP Binding Cassette Transporter, Subfamily G, Member 2; D018528:ATP-Binding Cassette Transporters; D000970:Antineoplastic Agents; D034261:Epothilones; D027425:ATP-Binding Cassette, Sub-Family C Proteins; D009363:Neoplasm Proteins; D017239:Paclitaxel; D020033:Protein Isoforms; D012333:RNA, Messenger; D014404:Tubulin; C513055:ABCB1 protein, human; C116614:ABCG2 protein, human; C498585:TUBB3 protein, human; C093788:epothilone B; C421109:multidrug resistance-associated protein 1