Uveal Melanoma Cell Line Proliferation Is Inhibited by Ricolinostat, a Histone Deacetylase Inhibitor

Abstract

Metastatic uveal melanoma (MUM) is characterized by poor patient survival. Unfortunately, current treatment options demonstrate limited benefits. In this study, we evaluate the efficacy of ACY-1215, a histone deacetylase inhibitor (HDACi), to attenuate growth of primary ocular UM cell lines and, in particular, a liver MUM cell line in vitro and in vivo, and elucidate the underlying molecular mechanisms. A significant (p = 0.0001) dose-dependent reduction in surviving clones of the primary ocular UM cells, Mel270, was observed upon treatment with increasing doses of ACY-1215. Treatment of OMM2.5 MUM cells with ACY-1215 resulted in a significant (p = 0.0001), dose-dependent reduction in cell survival and proliferation in vitro, and in vivo attenuation of primary OMM2.5 xenografts in zebrafish larvae. Furthermore, flow cytometry revealed that ACY-1215 significantly arrested the OMM2.5 cell cycle in S phase (p = 0.0001) following 24 h of treatment, and significant apoptosis was triggered in a time- and dose-dependent manner (p < 0.0001). Additionally, ACY-1215 treatment resulted in a significant reduction in OMM2.5 p-ERK expression levels. Through proteome profiling, the attenuation of the microphthalmia-associated transcription factor (MITF) signaling pathway was linked to the observed anti-cancer effects of ACY-1215. In agreement, pharmacological inhibition of MITF signaling with ML329 significantly reduced OMM2.5 cell survival and viability in vitro (p = 0.0001) and reduced OMM2.5 cells in vivo (p = 0.0006). Our findings provide evidence that ACY-1215 and ML329 are efficacious against growth and survival of OMM2.5 MUM cells.

MITF in Normal Melanocytes, Cutaneous and Uveal Melanoma: A Delicate Balance

“…Aligned with that, the HDAC trichostatin A (TSA) increases miR-137, which in turn reduces MITF expression in uveal melanoma cells [ 179 ]. A recent study showed that both the HDAC inhibitor ACY-1215 and a small molecule inhibitor of the MITF pathway (ML329) were able to reduce the proliferation of a metastatic UM cell line in vitro and caused regression of tumours derived from this cell line in zebrafish, but did not influence tumour dissemination [ 189 ]. Moreover, UM cells treated with ACY-1215 showed a concomitant decrease in the protein expression of MITF and several of its targets [ 189 ].…”

“…A recent study showed that both the HDAC inhibitor ACY-1215 and a small molecule inhibitor of the MITF pathway (ML329) were able to reduce the proliferation of a metastatic UM cell line in vitro and caused regression of tumours derived from this cell line in zebrafish, but did not influence tumour dissemination [ 189 ]. Moreover, UM cells treated with ACY-1215 showed a concomitant decrease in the protein expression of MITF and several of its targets [ 189 ]. This apparent contradiction, i.e., inhibition of HAT and HDAC leading to reduction of MITF activity, remains to be elucidated.…”

Role of Selective Histone Deacetylase 6 Inhibitor ACY-1215 in Cancer and Other Human Diseases

“…In non-Hodgkin’s lymphoma, ACY-1215 causes inactivation of AKT and ERK1/2, leading to increased DNA damage and ultimately tumor cells death ( Lee et al, 2019a ). In melanoma cells, ACY-1215 accelerates cell death by inhibiting ERK activation ( Peng et al, 2017 ; Sundaramurthi et al, 2022 ). In head and neck carcinoma cell, the suppression of p-Chk1 activity caused by ACY-1215 leads to synergistically enhanced apoptosis via mitotic catastrophe in a p53-dependent manner ( Miyake et al, 2022 ).…”

Evaluation of the Therapeutic Potential of Histone Deacetylase 6 Inhibitors for Primary and Metastatic Uveal Melanoma

“…Nencetti et al reported that novel compound VS13, with increased HDAC6 selectivity, significantly reduced 92.1 and Mel270 (primary) UM cell viability (up to a 100% reduction) in a dose-dependent manner [ 35 ]. Additionally, ACY-1215, a selective HDAC6i, induced a dose-dependent, significant reduction in UM and MUM cell survival by up to 99.99% in vitro and significantly decreased UM cell fluorescence by 65% in zebrafish xenografts with MUM (OMM2.5) cells in vivo [ 36 ].…”

“…The authors report using zebrafish models that loss of mitfa resulted in growth of UM tumors. In our study, we show a potential link between ACY-1215 inhibition and regulation of MITF in UM cells in vitro [ 36 ]. Contrarily, ACY-1215 treatment of MUM cells significantly downregulated MITF and MITF signaling pathway associated protein(s) expression levels, which probably contributed to the observed anti-tumor effects.…”