Retracted: Ras-ERK1/2 signaling promotes the development of uveal melanoma by downregulating H3K14ac

Recent Advances and Challenges in Uveal Melanoma Immunotherapy

Simple Summary

Uveal melanoma is the most common primary intraocular malignancy in adults. Although it can be controlled locally, half of the patients still develop metastases. To date, there have been no standard therapeutic strategies for the prevention or treatment of metastases. Existing therapies, such as chemotherapy and targeted therapies, induce only minimal responses. This review focuses on newly published research on immunotherapy. We highlight expanding treatments and their clinical outcomes, as well as propose promising new treatments and feasible checkpoints. Based on these findings, we provide innovative insights into feasible strategies for the treatment of patients with uveal melanoma.

Abstract

Uveal melanoma (UM) is the most common primary intraocular malignancy in adults. Compared to cutaneous melanoma (CM), which mainly harbors BRAF or NRAS mutations, UM predominantly harbors GNAQ or GNA11 mutations. Although primary UM can be controlled locally, approximately 50% of patients still develop metastases. To date, there have been no standard therapeutic strategies for the prevention or treatment of metastases. Unfortunately, chemotherapy and targeted therapies only induce minimal responses in patients with metastatic UM, with a median survival time of only 4–5 months after metastasis detection. Immunotherapy agents, such as immune checkpoint inhibitors, have achieved pioneering outcomes in CM but have shown limited effects in UM. Researchers have explored several feasible checkpoints to identify options for future therapies. Cancer vaccines have shown little in the way of therapeutic benefit in patients with UM, and there are few ongoing trials providing favorable evidence, but adoptive cell transfer-related therapies seem promising and deserve further investigation. More recently, the immune-mobilizing monoclonal T-cell receptor against the cancer molecule tebentafusp showed impressive antitumor effects. Meanwhile, oncolytic viruses and small molecule inhibitors have also gained ground. This review highlights recent progress in burgeoning treatments and provides innovative insights on feasible strategies for the treatment of UM.

ALKBH5-mediated m6A demethylation of FOXM1 mRNA promotes progression of uveal melanoma

In this study, we found that ALKBH5, a key component of the N⁶-methyladenosine (m⁶A) methyltransferase complex, was significantly elevated in uveal melanoma (UM) cell lines and that ALKBH5 downregulation inhibited tumor growth in vivo. High ALKBH5 expression predicted worse outcome in patients with UM. EP300-induced H3K27 acetylation activation increased ALKBH5 expression. Downregulation of ALKBH5 inhibited UM cell proliferation, migration, and invasion and increased apoptosis in vitro. Besides, ALKBH5 may promote UM metastasis by inducing epithelial-to-mesenchymal transition (EMT) via demethylation of FOXM1 mRNA, which increases its expression and stability. In sum, our study indicates that AKLBH5-induced m⁶A demethylation of FOXM1 mRNA promotes UM progression. Therefore, AKLBH5 is a potential prognostic biomarker and therapeutic target in UM.

The Ras-ERK signaling pathway regulates acetylated activating transcription factor 2 via p300 in pancreatic cancer cells

Background

Activating transcription factor 2 (ATF2) regulates the expression of downstream target genes and is phosphorylated by the Ras-extracellular-signal-regulated kinase (ERK) pathway. Acetylation of ATF2 is necessary for this type of regulation. However, the molecular mechanism by which the Ras-ERK pathway mediates the regulation of acetylated ATF2 is unknown. This study investigates the mechanism of Ras-ERK pathway-mediated regulation of acetylated ATF2 in maintaining the characteristic phenotype of pancreatic cancer cells.

Methods

This study was carried out using ASPC-1 and BXPC-3 pancreatic cancer cell lines transfected with the double mutant Ras^G12V/T35S. The levels of phosphorylated ERK1/2 were measured to establish the activated Ras-ERK pathway. The regulation of acetylated ATF2 was examined by detecting the protein level using western blotting, and the effects on cancer cell phenotype were measured using cell viability, proliferation, migration, and apoptosis assays. Also, chromatin immunoprecipitation (ChIP) assays were used to measure the effect on respective downstream target genes.

Results

The results showed that Ras^G12V/T35S reduced the level of acetylated ATF2 in ASPC-1 and BXPC-3 cells. Compared to wild-type ATF2, the mutant ATF2^K357Q (which mimics the irreversible acetylated form of ATF2) reduced the cancer cell phenotype and showed decreased enrichment on target genes upon transfection with Ras. Moreover, the level of acetylated ATF2 was regulated by the degradation of p300 through E3 ubiquitin ligase mouse double minute 2 homolog (MDM2).

Conclusions

Activation of the Ras-ERK pathway regulates acetylated ATF2 through degradation of p300 via a proteasome-dependent pathway, which alters the transcription of downstream target genes responsible for the cancer cell phenotype.

RNA m6 A methylation regulates uveal melanoma cell proliferation, migration, and invasion by targeting c-Met

N⁶ -methyladenosine (m⁶ A) is a novel epitranscriptomic marker that contributes to regulating diverse biological processes through controlling messenger RNA metabolism. However, it is unknown if m⁶ A RNA methylation affects uveal melanoma (UM) development. To address this question, we probed its function and molecular mechanism in UM. Initially, we demonstrated that global RNA m⁶ A methylation levels were dramatically elevated in both UM cell lines and clinical specimens. Meanwhile, we found that METTL3, a main m⁶ A regulatory enzyme, was significantly increased in UM cells and specimens. Subsequently, cycloleucine (Cyc) or METTL3 targeted small interfering RNA was used to block m⁶ A methylation in UM cells. We found that Cyc or silencing METTL3 significantly suppressed UM cell proliferation and colony formation through cell cycle G1 arrest, as well as migration and invasion by functional analysis. On the other hand, overexpression of METTL3 had the opposite effects. Furthermore, bioinformatics and methylated RNA immunoprecipitation-quantitative polymerase chain reaction identified c-Met as a direct target of m⁶ A methylation in UM cells. In addition, western blot analysis showed that Cyc or knockdown of METTL3 downregulated c-Met, p-Akt, and cell cycle-related protein levels in UM cells. Taken together, our results demonstrate that METTL3-mediated m⁶ A RNA methylation modulates UM cell proliferation, migration, and invasion by targeting c-Met. Such a modification acts as a critical oncogenic regulator in UM development.