Potential of the dual mTOR kinase inhibitor AZD2014 to overcome paclitaxel resistance in anaplastic thyroid carcinoma.
PURPOSE
Anaplastic thyroid carcinoma (ATC) is an aggressive, chemo-resistant malignancy. Chemo-resistance is often associated with changes in activity of the RAS/MAPK/ERK and PI3K/AKT/mTOR pathways and/or a high expression of ATP binding cassette (ABC) transporters, such as P-glycoprotein (P-gp) and breast cancer resistance protein (BCRP). To assess the therapeutic efficacy in ATC of a combination of the dual mTOR kinase inhibitor vistusertib (AZD2014) and paclitaxel (PTX), we generated a new cell line (Rho-) via the selection of human thyroid carcinoma 8505C cells that exhibit a low accumulation of rhodamine 123, which serves as a P-gp and BCRP substrate.


METHODS
Immunohistochemistry was used for P-gp and BCRP expression analyses in primary ATC patient samples. Spheroid formation and immunodeficient NSG mice were used for performing in vitro and in vivo tumorigenicity assays, respectively. MTT, flow-cytometry, fluorescent microscopy, cell death and proliferation assays, as well as migration, invasion and gelatin degradation assays, were used to assess the potential of AZD2014 to enhance the effects of PTX. ATC xenografts in SCID mice were used for evaluating in vivo treatment efficacies.


RESULTS
Rho- cells were found to be 10-fold more resistant to PTX than 8505C cells and, in addition, to be more tumorigenic. We also found that AZD2014 sensitized Rho- cells to PTX by inhibiting proliferation and by inducing autophagy. The combined use of AZD2014 and PTX efficiently inhibited in vitro ATC cell migration and invasion. Subsequent in vivo xenograft studies indicated that the AZD2014 and PTX combination effectively suppressed ATC tumor growth.


CONCLUSIONS
Our data support results from recent phase I clinical trials using combinations of AZD2014 and PTX for the treatment of solid tumors. Such combinations may also be employed for the design of novel targeted ATC treatment strategies.
['Milošević|Zorica|Z|', 'Banković|Jasna|J|', 'Dinić|Jelena|J|', 'Tsimplouli|Chrisiida|C|', 'Sereti|Evangelia|E|', 'Dragoj|Miodrag|M|', 'Paunović|Verica|V|', 'Milovanović|Zorka|Z|', 'Stepanović|Marija|M|', 'Tanić|Nikola|N|', 'Dimas|Kostantinos|K|', 'Pešić|Milica|M|http://orcid.org/0000-0002-9045-8239']
D000368:Aged D000369:Aged, 80 and over D000818:Animals D017209:Apoptosis D001549:Benzamides D016923:Cell Death D045744:Cell Line, Tumor D002465:Cell Movement D019008:Drug Resistance, Neoplasm D005260:Female D005434:Flow Cytometry D006801:Humans D007150:Immunohistochemistry D008297:Male D051379:Mice D016513:Mice, SCID D008875:Middle Aged D009025:Morpholines D017239:Paclitaxel D047428:Protein Kinase Inhibitors D011743:Pyrimidines D065646:Thyroid Carcinoma, Anaplastic D023041:Xenograft Model Antitumor Assays
mTOR AZD2014 Paclitaxel Anaplastic thyroid carcinoma Chemo-resistance Targeted therapy