Inhibition of ATM Increases the Radiosensitivity of Uveal Melanoma Cells to Photons and Protons

PURPL Represses Radiation-Induced Apoptosis to Promote Radioresistance in Cutaneous Melanoma by Direct Interfering With BID Cleavage

The rise of radioresistance in treating cutaneous melanoma challenges the efficacy of radiotherapy. Transcriptomic sequencing highlights PURPL as one of the top upregulated long noncoding RNAs in response to ionizing radiation (IR) treatment in melanoma cells, suggesting its role in radioresistance. To explore such hypothesis, loss-of-function experiments were conducted to assess the impact of PURPL on melanoma cell viability, colony formation, and migration. Mechanistic studies using RNA pulldown identified BID as the interacting protein partner of PURPL. Further analysis explored the relationship among PURPL, BID, and Caspase-8 in the context of IR-induced DNA damage and apoptosis through loss-of- and gain-of-function experiments. The findings demonstrated that silencing PURPL significantly repressed melanoma cell viability, colony formation, migration, and invasiveness, indicating its potential role in promoting radioresistance. Moreover, PURPL was shown to repress IR-induced DNA damage and apoptosis, supporting its involvement in melanoma radioresistance. Mechanistically, PURPL inhibited the interaction between BID and Caspase-8, thereby modulating the mitochondrial apoptosis pathway and promoting radioresistance. In conclusion, this study provides evidence supporting the pro-radioresistance role of PURPL in melanoma. In vivo assays further corroborated the in vitro findings, highlighting the potential clinical relevance of targeting PURPL in radioresistant melanoma. By interfering with the association between BID and Caspase-8, PURPL may serve as a novel therapeutic target for clinical radiotherapy during the treatment of melanoma.

Potential Benefits of Combining Proton or Carbon Ion Therapy with DNA Damage Repair Inhibitors

The use of charged particle radiotherapy is currently increasing, but combination therapy with DNA repair inhibitors remains to be exploited in the clinic. The high-linear energy transfer (LET) radiation delivered by charged particles causes clustered DNA damage, which is particularly effective in destroying cancer cells. Whether the DNA damage response to this type of damage is different from that elicited in response to low-LET radiation, and if and how it can be targeted to increase treatment efficacy, is not fully understood. Although several preclinical studies have reported radiosensitizing effects when proton or carbon ion irradiation is combined with inhibitors of, e.g., PARP, ATR, ATM, or DNA-PKcs, further exploration is required to determine the most effective treatments. Here, we examine what is known about repair pathway choice in response to high- versus low-LET irradiation, and we discuss the effects of inhibitors of these pathways when combined with protons and carbon ions. Additionally, we explore the potential effects of DNA repair inhibitors on antitumor immune signaling upon proton and carbon ion irradiation. Due to the reduced effect on healthy tissue and better immune preservation, particle therapy may be particularly well suited for combination with DNA repair inhibitors.

Genetic status affects disease-specific mortality but not the incidence of local recurrence in patients with uveal melanoma

OBJECTIVE

Increased disease-specific mortality has been observed among patients with local recurrence (LR) from uveal melanoma, but the underlying mechanism is unknown. The purpose of this study was to determine if copy number alterations of chromosomes 3 and 8q, at the time of diagnosis, increase the incidence of LR and if disease-specific mortality among patients with LR depends on the chromosome status of the primary tumor.

STUDY DESIGN

Retrospective cohort study SUBJECTS: The study included 239 consecutive patients with primary uveal melanoma (choroidal or ciliary body) treated with Ru-106 brachytherapy, from January 2009 to December 2019 at a single national referral center.

METHODS

Cox-regression modelling and Kaplan-Meier analyses were used to assess the effect of chromosomes 3 and 8q status on the incidence of LR and disease-specific mortality following the event of LR. Multistate models were used to illustrate the probabilities over time of patients being: 'alive and disease-free', 'alive with LR', 'dead from uveal melanoma metastases', or 'dead from other causes' split on chromosomes 3 and 8q status.

MAIN OUTCOME MEASURES

LR incidence and disease-specific mortality RESULTS: LR was observed in 42 patients (16%). Overall incidence of LR was not affected by chromosome 3 and 8q status (p=0.87), albeit LR occurred earlier in patients with aberrations of chromosomes 3 and/or 8q compared to patients with normal copy number of chromosomes 3 and 8q, median time from primary diagnosis to LR was 1.6 years (IQR: 1.0-2.0) and 3.2 years (IQR 2.1-5.0), respectively. Cox regression found LR to be an independent risk factor for disease-specific mortality (HR 2.7 (95%CI 1.5-5.0) among all patients, but multistate models demonstrated very low risk of disease-specific death among patients with normal chromosomes 3 and 8q status, even following a LR.

CONCLUSIONS

Copy number alterations of chromosomes 3 or 8q in the primary uveal melanoma did not increase the overall incidence of LR. However, the development of a LR enhanced the risk of disease-specific mortality among patients with copy number alterations of chromosomes 3 and/or 8q. Even after a LR, disease-specific mortality remained low among patients with normal copy numbers of chromosomes 3 and 8q.

The Adrenergic Receptor Antagonist Carvedilol Elicits Anti-Tumor Responses in Uveal Melanoma 3D Tumor Spheroids and May Serve as Co-Adjuvant Therapy with Radiation

Uveal melanoma (UM) is the most common intraocular tumor in adults. Despite local tumor control, no effective therapy has been found to prevent metastasis, resulting in a high mortality rate. In the present study, we evaluated the anti-tumor potential of non-selective ß-blockers in 3D tumor spheroids grown from UM cell lines. Of the various ß-blockers tested, carvedilol and its enantiomers were most potent in decreasing the viability of Mel270 spheroids. Carvedilol at a concentration of 10–50 µM significantly elicited cytotoxicity and induced apoptosis in spheroid cells. In result, carvedilol inhibited tumor spheroid growth and compactness, and furthermore prevented the long-term survival and repopulation of spreading spheroid cells. The drug sensitivity of the different spheroids grown from Mel270, 92-1, UPMD2, or UPMM3 cell lines was dependent on 3D morphology rather than on high-risk cytogenetic profile or adrenergic receptor expression levels. In fact, the monosomy-3-containing UPMM3 cell line was most responsive to carvedilol treatment compared to the other cell lines. The concurrent treatment of UPMM3 spheroids with carvedilol and 5 or 10 Gy irradiation revealed additive cytotoxic effects that provided tumor control. Collectively, our data demonstrate the anti-tumor properties of carvedilol and its enantiomers, which may serve as candidates for the co-adjuvant therapy of UM.

Novel Therapeutic Approaches with DNA Damage Response Inhibitors for Melanoma Treatment

Targeted therapies against components of the mitogen-activated protein kinase (MAPK) pathway and immunotherapies, which block immune checkpoints, have shown important clinical benefits in melanoma patients. However, most patients develop resistance, with consequent disease relapse. Therefore, there is a need to identify novel therapeutic approaches for patients who are resistant or do not respond to the current targeted and immune therapies. Melanoma is characterized by homologous recombination (HR) and DNA damage response (DDR) gene mutations and by high replicative stress, which increase the endogenous DNA damage, leading to the activation of DDR. In this review, we will discuss the current experimental evidence on how DDR can be exploited therapeutically in melanoma. Specifically, we will focus on PARP, ATM, CHK1, WEE1 and ATR inhibitors, for which preclinical data as single agents, taking advantage of synthetic lethal interactions, and in combination with chemo-targeted-immunotherapy, have been growing in melanoma, encouraging the ongoing clinical trials. The overviewed data are suggestive of considering DDR inhibitors as a valid therapeutic approach, which may positively impact the future of melanoma treatment.

LINC01224 facilitates the proliferation and inhibits the radiosensitivity of melanoma cells through the miR-193a-5p/NR1D2 axis

Melanoma is a skin cancer characterized by early metastasis and high mortality. Radiotherapy is a common treatment for melanoma in patients. Long noncoding RNAs play pivotal roles in regulating the radiosensitivity of many tumors, including melanomas. In this study, the role of LINC01224 in the radiosensitivity of melanoma cells was explored. The expression of LINC01224 in melanoma was examined by reverse transcription-quantitative polymerase chain reaction, and the results showed that LINC01224 was upregulated in melanoma tissues and cells. The effects of LINC01224 on cell proliferation and apoptosis in melanoma were assessed by 3-(4,5-Dimethylthiazol-2-yl)-2,5-Diphenyltetrazolium Bromide (MTT), colony formation, and flow cytometry assays. The effects of LINC01224 on the radiosensitivity of melanoma were analyzed by colony formation assay. The results implied that LINC01224 knockdown inhibited cell viability and proliferation but enhanced cell apoptosis and radiosensitivity. Luciferase reporter and RNA pull-down assays were performed to evaluate the relationships between LINC01224 and miR-193a-5p or miR-193a-5p and nuclear receptor subfamily 1 group D member 2 (NR1D2). We found that LINC01224 binds to miR-193a-5p, which directly targets NR1D2. In addition, we discovered that LINC01224 upregulated NR1D2 expression by sponging miR-193a-5p in melanoma cells. Overall, the data collected in this study suggest that LINC01224 exerts oncogenic effects in melanoma via the miR-193a-5p/NR1D2 axis.

Radiation therapy for uveal melanoma: a review of treatment methods available in 2021

PURPOSE OF REVIEW

Radiation therapy has become the standard of care for the treatment of uveal melanoma. We intend to outline the current radiation therapy methods that are employed to treat uveal melanoma. We will outline their relative benefits over one another. We will also provide some background about radiation therapy in general to accustom the ophthalmologists likely reading this review.

RECENT FINDINGS

Four main options exist for radiation therapy of uveal melanoma. Because the eye is a small space, and because melanomas are relatively radioresistant, oncologists treating uveal melanoma must deliver highly focused doses in high amounts to a small space. Therapies incorporating external beams include proton beam therapy and stereotactic radiosurgery. Stereotactic radiosurgery comes in two forms, gamma knife therapy and cyberknife therapy. Radiation may also be placed directly on the eye surgically via plaque brachytherapy. All methods have been used effectively to treat uveal melanoma.

SUMMARY

Each particular radiotherapy technique employed to treat uveal melanoma has its own set of benefits and drawbacks. The ocular oncologist can choose amongst these therapies based upon his or her clinical judgment of the relative risks and benefits. Availability of the therapy and cost to the patient remain significant factors in the ocular oncologist's choice.

Transcriptome Profiling Reveals New Insights into the Immune Microenvironment and Upregulation of Novel Biomarkers in Metastatic Uveal Melanoma

Simple Summary

Uveal melanoma (UM) is a rare aggressive eye cancer. Although treatment of the eye tumour is successful, about 50% of UM patients develop a relapse of their cancer in the liver. At present, such advanced disease is not curable. A better understanding of the metastatic UM (mUM) in the liver is essential to improve patient survival. This study examines both the response of immune cells within the liver to the UM secondaries (metastases), as well as the expression of various proteins by the UM cells. Our study demonstrates that there is a limited immune response to the mUM, but reveals that a certain type of reactive immune cell: a protumourigenic subset of macrophage is dominant within the mUM. Our research also reveals novel proteins within the mUM, which are specific to these cells and therefore may be targetable in future therapies.

Abstract

Metastatic uveal melanoma (mUM) to the liver is incurable. Transcriptome profiling of 40 formalin-fixed paraffin-embedded mUM liver resections and 6 control liver specimens was undertaken. mUMs were assessed for morphology, nuclear BAP1 (nBAP1) expression, and their tumour microenvironments (TME) using an “immunoscore” (absent/altered/high) for tumour-infiltrating lymphocytes (TILs) and macrophages (TAMs). Transcriptomes were compared between mUM and control liver; intersegmental and intratumoural analyses were also undertaken. Most mUM were epithelioid cell-type (75%), amelanotic (55%), and nBAP1-ve (70%). They had intermediate (68%) or absent (15%) immunoscores for TILs and intermediate (53%) or high (45%) immunoscores for TAMs. M2-TAMs were dominant in the mUM-TME, with upregulated expression of ANXA1, CD74, CXCR4, MIF, STAT3, PLA2G6, and TGFB1. Compared to control liver, mUM showed significant (p < 0.01) upregulation of 10 genes: DUSP4, PRAME, CD44, IRF4/MUM1, BCL2, CD146/MCAM/MUC18, IGF1R, PNMA1, MFGE8/lactadherin, and LGALS3/Galectin-3. Protein expression of DUSP4, CD44, IRF4, BCL-2, CD146, and IGF1R was validated in all mUMs, whereas protein expression of PRAME was validated in 10% cases; LGALS3 stained TAMs, and MFGEF8 highlighted bile ducts only. Intersegmental mUMs show differing transcriptomes, whereas those within a single mUM were similar. Our results show that M2-TAMs dominate mUM-TME with upregulation of genes contributing to immunosuppression. mUM significantly overexpress genes with targetable signalling pathways, and yet these may differ between intersegmental lesions.