Melanoblast transcriptome analysis reveals novel pathways promoting melanoma metastasis

Abstract

Cutaneous malignant melanoma is an aggressive cancer of melanocytes with a strong propensity to metastasize. We posited that melanoma cells acquire metastatic capability by adopting an embryonic-like phenotype, and that a lineage approach would uncover novel metastatic melanoma biology. We used a genetically engineered mouse model to generate a rich melanoblast transcriptome dataset, identified melanoblast-specific genes whose expression contributed to metastatic competence, and derived a 43-gene signature that predicted patient survival. We identified a melanoblast gene, KDELR3, whose loss impaired experimental metastasis. In contrast, KDELR1 deficiency enhanced metastasis, providing the first example of different disease etiologies within the KDELR-family of retrograde transporters. We show that KDELR3 regulates the metastasis suppressor, KAI1, and report an interaction with the E3 ubiquitin-protein ligase gp78, a regulator of KAI1 degradation. Our work demonstrates that the melanoblast transcriptome can be mined to uncover novel targetable pathways for melanoma therapy.Melanoma is an aggressive cancer that frequently progresses to metastatic proficiency. Treatment of metastatic melanoma remains a challenge, highlighting an urgent need to uncover new targets that could be used in the clinic to broaden therapeutic options. In the early 19 th century, Virchow first described cancer cells as being "embryonic-like" 1 . Developmental systems have since proven useful to study melanoma, and melanoma cell plasticity appears to be a key feature of melanoma progression. Melanocyte lineage pathways are a recurring theme in melanoma etiology, reinforcing the importance of uncovering new melanocyte developmental pathways and biology 2-13 . Here we use a genetically engineered mouse (GEM), designed to facilitate the isolation and analysis of developing melanocytes (melanoblasts), to attempt to uncover new targets relevant to melanoma metastasis.Melanocytes are neural crest-derived cells whose development necessitates extensive migration/invasion to populate the skin and other sites 14 . This process requires melanoblasts to adopt a migratory phenotype, to interact with and survive in foreign microenvironments and to colonize distant sites − functions that are analogous to metastatic competence 15 . To complete these processes, the cell may encounter numerous cellular stressors, such as shear stress, nutrient deprivation, hypoxia, lipid stress and oxidative stress 16 . The cellular impact of these stressors converges at the Endoplasmic Reticulum (ER), the organelle tied closely to protein synthesis and responsible for correct protein folding, protein quality control and post-translational modifications.Stress stimuli can result in aberrant ER function, a build-up of unfolded/misfolded proteins (ER stress), and an overwhelmed system. The ER can therefore be viewed as an exquisitely sensitive stress sensor. Upon ER stress insult, the ER launches an immediate counter measure known as of the Unfolded Protein Response (UPR) 17 . T...

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“…It has been reported that to improve melanoma treatment, the authors performed a transcriptomic analysis and identified a melanoblast-specific gene, KDELR3, the deletion of which impairs experimental metastasis (12). Transcriptomic analysis offers a powerful means for mechanistic studies and for biomarker identification, and the most common method for transcriptomic analysis is RNA sequencing, which may be an effective approach for our study.…”

Targeting the SHP2 phosphatase promotes vascular damage and inhibition of tumor growth

“…1D). The other six mouse cancer models differed from the B16F10 model in having only a proportion of vessels displaying p-EphrinB (Lewis lung carcinoma/LLC1, 9013BL/M2 and Mel114433/M1 melanoma (12), HT29 colon, MOPC-315 plasmacytoma and displaying p-EphrinB2 in infiltrating Gr1 + myeloid cells (mammary 4T1) ( Supplementary Fig. 1A,B and (13)).…”