Dual Inhibition of Histone Deacetylases and the Mechanistic Target of Rapamycin Promotes Apoptosis in Cell Line Models of Uveal Melanoma

Abstract

Purpose Over 90% of uveal melanomas harbor pathogenic variants of the GNAQ or GNA11 genes that activate survival pathways. As previous studies found that Ras-mutated cell lines were vulnerable to a combination of survival pathway inhibitors and the histone-deacetylase inhibitor romidepsin, we investigated whether this combination would be effective in models of uveal melanoma. Methods A small-scale screen of inhibitors of bromodomain-containing protein 4 (BRD4; OTX-015), extracellular signal-related kinase (ERK; ulixertinib), mechanistic target of rapamycin (mTOR; AZD-8055), or phosphoinositide 3-kinase (PI3K; GDC-0941) combined with a clinically relevant administration of romidepsin was performed on a panel of uveal melanoma cell lines (92.1, Mel202, MP38, and MP41) and apoptosis was quantified by flow cytometry after 48 hours. RNA sequencing analysis was performed on Mel202 cells treated with romidepsin alone, AZD-8055 alone, or the combination, and protein changes were validated by immunoblot. Results AZD-8055 with romidepsin was the most effective combination in inducing apoptosis in the cell lines. Increased caspase-3 and PARP cleavage were noted in the cell lines when they were treated with romidepsin and mTOR inhibitors. RNA sequencing analysis of Mel202 cells revealed that apoptosis was the most affected pathway in the romidepsin/AZD-8055-treated cells. Increases in pro-apoptotic BCL2L11 and decreases in anti-apoptotic BIRC5 and BCL2L1 transcripts noted in the sequencing analysis were confirmed at the protein level in Mel202 cells. Conclusions Our data suggest that romidepsin in combination with mTOR inhibition could be an effective treatment strategy against uveal melanoma due in part to changes in apoptotic proteins.

PKC-independent PI3K signalling diminishes PKC inhibitor sensitivity in uveal melanoma

“…Effective drug concentrations were selected based on viability assays performed on a panel of uveal melanoma cell lines (Supplementary Fig. S1 ) and a review of relevant literature [ 8 , 13 – 16 ].…”

Reversing vemurafenib‐resistance in primary melanoma cells by combined romidepsin and type I IFN treatment through blocking of tumorigenic signals and induction of immunogenic effects

“…The selective HDAC1/2 inhibitor romidepsin, a drug approved in cutaneous and peripheral T cell lymphomas, induces cell cycle arrest and apoptosis in solid tumors 14 . Romidepsin is effective in the nanomolar range to induce radiosensitizing effects in lung and bladder tumors, and in combination with mTOR inhibition has been reported to be effective against uveal melanoma 15,16 . Recent reports highlighted the immunomodulatory properties of romidepsin, including the regulation of PD‐L1 expression, associated to modulation of antitumor effects in solid tumors 17 …”

“…14 Romidepsin is effective in the nanomolar range to induce radiosensitizing effects in lung and bladder tumors, and in combination with mTOR inhibition has been reported to be effective against uveal melanoma. 15,16 Recent reports highlighted the immunomodulatory properties of romidepsin, including the regulation of PD-L1 expression, associated to modulation of antitumor effects in solid tumors. 17 In our study, we sought to evaluate whether the combination of romidepsin with IFN-α2b, an immunomodulatory cytokine widely used in the past for melanoma treatment 18 could exert antitumor and immunogenic activity against BRAF-mutated melanoma and BRAFi acquired resistance.…”

PI3K/mTOR Dual Inhibitor Pictilisib Stably Binds to Site I of Human Serum Albumin as Observed by Computer Simulation, Multispectroscopic, and Microscopic Studies

“…Pictilisib (GDC-0941, C23H27N7O3S2, Figure 1) is a potent and selective dual inhibitor of class I PI3K and mTOR and shows favorable pharmacokinetic and toxicological properties when orally administered as a single agent or in combination with chemotherapy agents [17]. Pictilisib is currently undergoing phase II clinical trials for breast cancer [19], ovarian cancer [20], melanoma [21], and multiple myeloma treatment [22]. Clinical studies showed that GDC-0941 has a rapid absorption following oral administration and a dose-proportional pharmacokinetic profile [23].…”