title: The role of mTOR during cisplatin treatment in an in vitro and ex vivo model of cervical cancer.
abstract: Cisplatin is used as a cytotoxic agent for the management of cervical cancer. However, the severity of the side-effects limits the use of this drug, particularly at high doses. Resistance to cisplatin is often attributed to a disruption in the normal apoptotic response via aberrant activation of pathways such as the mTOR pathway. Here we assess the role of mTOR and its effect on cell death sensitization and autophagy in response to a low concentration of cisplatin in cervical cancer cells. Additionally we measured the expression profile of mTOR in normal, low- and high-grade squamous intraepithelial (LSIL and HSIL) lesions and cancerous tissue. An in vitro model of cervical cancer was established using HeLa and CaSki cells. mTOR protein expression as well as autophagy-related proteins were evaluated through Western blotting. Inhibition of mTOR was achieved with the use of rapamycin and RNA silencing. A low concentration of cisplatin administered as a single agent induces autophagy, but not apoptosis. Cisplatin cytotoxicity was greatly enhanced in cancer cells when mTOR had been inhibited prior to cisplatin treatment which was likely due to autophagy being increased above cisplatin-induced levels, thereby inducing apoptosis. Cervical tissue samples revealed an increase in mTOR protein expression in LSIL and carcinoma tissue which suggests a change in autophagy control. Our data suggest that utilising a lower dose of cisplatin combined with mTOR inhibition is a viable treatment option and addresses the challenge of cisplatin dose-dependent toxicity, however future studies are required to confirm this in a clinical setting.
authors.affiliation: Department of Physiological Sciences, Stellenbosch University, c/o Merriman and Bosman Road, Stellenbosch, South Africa. Electronic address: ginal@sun.ac.za.
authors.forename: G R
authors.initials: GR
authors.lastname: Leisching
authors.affiliation: Department of Physiological Sciences, Stellenbosch University, c/o Merriman and Bosman Road, Stellenbosch, South Africa.
authors.forename: B
authors.initials: B
authors.lastname: Loos
authors.affiliation: Department of Obstetrics and Gynaecology, Stellenbosch University, Francie van Zyl Avenue, Tygerberg South Africa.
authors.forename: M H
authors.initials: MH
authors.lastname: Botha
authors.affiliation: Department of Physiological Sciences, Stellenbosch University, c/o Merriman and Bosman Road, Stellenbosch, South Africa.
authors.forename: A-M
authors.initials: AM
authors.lastname: Engelbrecht
mesh_terms: D000970:Antineoplastic Agents / Q000494:pharmacology* / Q000633:toxicity; D000971:Antineoplastic Combined Chemotherapy Protocols / Q000494:pharmacology; D017209:Apoptosis / Q000187:drug effects; D001343:Autophagy / Q000187:drug effects*; D002453:Cell Cycle / Q000187:drug effects; D002945:Cisplatin / Q000494:pharmacology* / Q000633:toxicity; D004305:Dose-Response Relationship, Drug; D005260:Female; D015972:Gene Expression Regulation, Neoplastic; D006367:HeLa Cells; D006801:Humans; D047428:Protein Kinase Inhibitors / Q000494:pharmacology; D034622:RNA Interference; D015398:Signal Transduction / Q000187:drug effects; D020123:Sirolimus / Q000494:pharmacology; D065310:Squamous Intraepithelial Lesions of the Cervix / Q000201:enzymology* / Q000235:genetics / Q000473:pathology; D058570:TOR Serine-Threonine Kinases / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D014162:Transfection; D002583:Uterine Cervical Neoplasms / Q000201:enzymology* / Q000473:pathology
chemical_list: D000970:Antineoplastic Agents; D047428:Protein Kinase Inhibitors; C546842:MTOR protein, human; D058570:TOR Serine-Threonine Kinases; D002945:Cisplatin; D020123:Sirolimus
keywords: Apoptosis; Cervical cancer; Chemotherapy; Cisplatin; mTOR