Abstract 95: In vitro, in vivo and molecular effects of triptolide and minnelide in renal cell carcinoma
Authors: Chavez Valery A. , Bustamante Floritza , Murray Abner , Saluja Ashok , Merchan Jaime 
Published: June 2022

Background: The worldwide incidence of Renal Cell Carcinoma (RCC) is increasing. Although new therapies have improved outcomes in advanced RCC, most patients eventually fail treatment and succumb to this devastating disease. Systemic therapy strategies have focused on TKI and immunotherapy, alone or in combination. Triptolide, a diterpenoid epoxide extracted from Tripterygium wilfordii Hook f (TWHf), has potent antitumor activity in multiple cancer models. Few studies have focused on the potential of triptolide as a novel therapeutic option in RCC.

Objective: the objectives of this study are to characterize the in vitro and in vivo effects of Triptolide (T) and its water-soluble form, Minnelide (M), in models of renal cell carcinoma.

Methods: The in vitro effects of triptolide (T) on human and murine RCC (786-0, A498, Caki-1, ACHN, and RENCA) cell proliferation was assessed using cell count and xCelligence assays at 24, 48, 72 and 96h. Molecular and mechanistic characterization of triptolide’s effects in 786-0 cells were analyzed by the (Reverse Phase Protein Array) and validated by western blot analysis. The in vivo effects (tumor progression and survival) of M were assessed in nude mice bearing 786-0 tumors (8x106 cells per mouse). M was administered to tumor-bearing mice at two different doses (0.21mg/kg and 0.42mg/kg daily), intraperitoneally, for 21 days. Correlative studies to explain the in vivo effect of M and the correlation with the molecular changes in vitro seen are being performed and will be shown in the poster.

Results: T significantly inhibited, in a dose-response manner, cell proliferation in all human and murine renal cancer cell lines, with IC50 ranging between 12.5 and 25 nM). T was associated with significant negative modulation of proliferation, cell cycle, survival, increased apoptosis, and ER stress pathways in 786-0 cells, as demonstrated by RPPA analysis and validated by western Blot of selected pathway proteins, such as apoptosis (PARP cleavage and Caspase 3 activation), ER stress induction (pEIF2a, CHOP), and down-regulation of survival and proliferation pathways (pAKT). In vivo, M was associated with significant antitumor effects in 786-0 xenografts, with complete responses in the majority of mice while on treatment. These effects were associated with significant prolongation in overall survival in M treated vs. control mice. No significant toxicity or treatment-related deaths were observed.

Conclusion: Our results have shown for the first time the potent in vitro and in vivo antitumor effects of T in RCC and the molecular changes associated with these effects. The profound antitumor effects in the aggressive 786-0 RCC xenograft model are highly encouraging and warrant further preclinical studies and potential clinical trials of M this devastating disease. Correlative tumor studies to understand the mechanisms of M in vivo antitumor effects are underway and will be presented at the meeting.

Citation Format: Valery A. Chavez, Floritza Bustamante, Abner Murray, Ashok Saluja, Jaime Merchan. In vitro, in vivo and molecular effects of triptolide and minnelide in renal cell carcinoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 95.