Miley, David R.

The objective of this study was to compare drug response of uveal melanoma patient-derived cell lines (PDLs) and patient-derived organoids (PDOs) with response of commercially available cell lines and contextualize laboratory outputs in terms of clinical trial results. Uveal melanoma commercial cell lines, PDLs, and PDOs were treated with drugs that were ultimately utilized in clinical trials. Four treatments were chosen for promising laboratory results that failed to yield clinical response, while darovasertib was a surrogate positive control given initial favorable clinical trial data in the neoadjuvant setting. Drug concentrations were matched to laboratory work that supported progression to clinical trials. Viability was measured using PrestoBlueHS Cell Viability Reagent. Commercial cell lines showed promising viability reduction similar to prior laboratory results with treatments, including 5-μM darovasertib, 700-nM selumetinib, 700-nM selumetinib + 1000-nM MK-2206, 500-nM sotrastaurin + 1000-nM alpelisib, and 100-nM trametinib, with overall viability reduced to 32.5% for all drugs. However, PDLs (viability 52.8%) and PDOs (viability 80.4%) showed more treatment resistance ( P < 0.05), better simulating ultimate lack of efficacy found in clinical trials. While uveal melanoma with BAP1 loss demonstrated greater treatment resistance under some conditions, other factors such as cell morphology or culture in a three-dimensional environment appeared to be more consistent drivers of therapeutic sensitivity. PDLs and PDOs may more accurately represent uveal melanoma clinical response. Demonstrating efficacy of novel therapeutics in these models could improve the likelihood of successful translation for future clinical trials, but future studies are needed to define clinically meaningful in-vitro response thresholds.

Radiation exposure to the eye during cancer treatment can lead to ocular radiation injury (ORI), a devastating condition that can have a profound and permanent impact on vision-related quality of life. Rodent models do not have adequate ocular anatomy to accurately simulate human ORI, and modeling in non-human primates is limited by logistical and ethical concerns. To improve future translational research investigating ways to treat or prevent ORI, we developed protocols for a tree shrew model of ORI. Northern tree shrews (Tupaia belangeri) were obtained by our laboratory. Custom housing and handling methods were developed, including custom body suits to maintain the tree shrew’s body temperature during procedures. Radiation delivery was optimized to accurately deliver radiation, and imaging was performed to observe fundus changes from ORI. Optimization of tree shrew handling, housing, anesthesia approaches, radiation delivery, and clinically-relevant ocular imaging permitted successful induction and assessment of ORI in tree shrews. With these protocols, tree shrews can be used as a highly relevant model organism with key anatomic features similar to humans to study ORI.

To investigate downstream molecular changes caused by mitogen-activated protein kinase (MEK) inhibitor treatment and further explore the impact of direct knockdown of early growth response-1 (EGR1) in melanoma cell culture. RNA-sequencing (RNA-Seq) was performed to determine gene expression changes with MEK inhibitor treatment. Treatment with MEK inhibitor (trametinib) was then assessed in two cutaneous (MEL888, MEL624) and one conjunctival (YUARGE 13-3064) melanoma cell line. Direct knockdown of EGR1 was accomplished using lentiviral vectors containing shRNA. Cell viability was measured using PrestoBlueHS Cell Viability Reagent. Total RNA and protein were assessed by qPCR and SimpleWestern. RNA-Seq demonstrated a profound reduction in EGR1 with MEK inhibitor treatment, prompting further study of melanoma cell lines. Following trametinib treatment of melanoma cells, viability was reduced in both cutaneous (MEL888 26%, P < 0.01; MEL624 27%, P < 0.001) and conjunctival (YUARGE 13-3064 33%, P < 0.01) melanoma compared with DMSO control, with confirmed EGR1 knockdown to 0.04-, 0.01-, and 0.16-fold DMSO-treated levels (all P < 0.05) in MEL888, MEL624, and YUARGE 13-3064, respectively. Targeted EGR1 knockdown using shRNA reduced viability in both cutaneous (MEL624 78%, P = 0.05) and conjunctival melanoma (YUARGE-13-3064 67%, P = 0.02). RNA-Sequencing in MEK inhibitor-treated cells identified EGR1 as a candidate effector molecule of interest. In a malignant melanoma cell population, MEK inhibition reduced viability in both cutaneous and conjunctival melanoma with a profound downstream reduction in EGR1 expression. Targeted knockdown of EGR1 reduced both cutaneous and conjunctival melanoma cell viability independent of MEK inhibition, suggesting a key role for EGR1 in melanoma pathobiology.