Melanoma addiction to the long non-coding RNA SAMMSON

Area of Science:

• Oncology
• Molecular Biology
• Genetics

Background:

• Focal amplifications at chromosome 3p13-3p14 are found in ~10% of melanomas, correlating with poor prognosis.
• The melanoma-specific oncogene MITF is located at the center of this amplicon, but the roles of other co-amplified genes remain unclear.

Purpose of the Study:

• To investigate the role of the long non-coding RNA (lncRNA) gene SAMMSON, located within the 3p13-3p14 amplicon, in melanoma development and therapeutic response.

Main Methods:

• Analysis of SAMMSON co-amplification with MITF in melanoma.
• Assessing SAMMSON expression in melanoma cells and patient samples.
• Investigating the functional impact of SAMMSON modulation (overexpression and knockdown) on melanoma cell viability and clonogenicity.
• Evaluating the effect of SAMMSON targeting on melanoma sensitivity to MAPK inhibitors in vitro and in vivo.
• Elucidating the molecular mechanism of SAMMSON action, including its interaction with p32 and mitochondrial function.

Main Results:

• SAMMSON is consistently co-gained with MITF in 3p13-3p14 amplifications and is a SOX10 target, expressed in over 90% of melanomas.
• SAMMSON overexpression enhances melanoma cell clonogenicity, while its knockdown severely impairs cell viability across different melanoma subtypes.
• Targeting SAMMSON sensitizes melanoma cells to MAPK-targeting therapies in vitro and in patient-derived xenografts.
• SAMMSON interacts with p32, promoting its mitochondrial localization and pro-oncogenic activity, thereby disrupting mitochondrial homeostasis.

Conclusions:

• SAMMSON acts as a lineage addiction oncogene in melanoma.
• Silencing SAMMSON disrupts essential mitochondrial functions in a cancer-specific manner.
• Targeting SAMMSON holds promise for developing effective and tissue-restricted anti-melanoma therapies.