Searchable abstracts of presentations at key conferences in endocrinology
Endocrine Abstracts (2016) 41 EP628 | DOI: 10.1530/endoabs.41.EP628

ECE2016 Eposter Presentations Endocrine tumours and neoplasia (68 abstracts)

Potential role of vitamin D in restoring sensitivity to mTOR inhibitors in hepatocellular carcinoma (HCC): 1,25(OH)vitamin D (VITD) reverts everolimus (EVE) resistance in a HCC cell line

Claudia Pivonello 1 , Donatella Paola Provvisiero 1 , Mariarosaria Negri 1 , Gilda Di Gennaro 1 , Cristina De Angelis 2 , Giacomo Galdiero 1 , Chiara Simeoli 1 , Maria Cristina De Martino 1 , Annamaria Colao 1 & Rosario Pivonello 1

1Department of Clinical Medicine and Surgery, University of Naples Federico II, Naples, Italy; 2IOS & Coleman Medicina Futura Medical Center, Centro Direzionale, Naples, Italy.

HCC is a difficult-to-treat- cancer with poor prognosis. The recent EVOLVE-1 trial demonstrated that EVE did not improve overall survival in molecularly and clinically unselected patients with advanced HCC resistant to sorafenib treatment. In selected patients, the well-established antitumor effect of EVE could make this drug a potential adjuvant therapy. Unfortunately, the acquired resistance to this molecule due to the tumor adaptation to chronic drug use is a current challenge. VitD has been deemed as potential regimen to treat a variety of cancers alone or in combination with other drugs. The aim of this study was to assess the antiproliferative effect of the combined treatment with EVE and VitD in JHH-6, a model of HCC cell line, and to explore the role of VitD pre-treatment in the re-sensitization to EVE in JHH-6 cell line resistant to EVE (JHH-6 RR). JHH-6 RR were obtained after 4 months of treatment with EVE 10−8 M. Messenger and protein VitD receptor (VDR) expression was confirmed by RT-qPCR and immunofluorescence. DNA assay was established to evaluate the proliferation rate in basal and resistant cells after EVE treatment (from 10−14 M to 10−8 M) alone or in combination with VitD (10−7 M). In basal condition, EVE significantly reduced the proliferation index in a dose-dependent manner after 6 days of treatment and VitD did not improve EVE effect. JHH-6 RR cells no longer responded to EVE treatment but 12 h of VitD pre-treatment was sufficient to significantly restore the efficacy of EVE at concentration ranging from 10−14 M to 10−8 M with a minimum effect of 14% of inhibition at 10−14 M (P<0.01) and a maximum effect of 35.3% at 10−8 M (P<0.001). These preliminary data suggested the use of VitD to overcome the acquired resistance to EVE in HCC.

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