Inverse regulation of melanoma growth and migration by Orai1/STIM2-dependent calcium entry

Area of Science:

• Oncology
• Cell Biology
• Biochemistry

Background:

• Melanoma phenotype switching is influenced by environmental factors, impacting patient outcomes and treatment response.
• The precise mechanisms controlling melanoma plasticity remain largely unknown.
• Store-operated calcium (Ca2+) entry is a critical cellular process implicated in various cancers.

Purpose of the Study:

• To investigate the role of Orai1 and STIM2 proteins in human melanoma.
• To determine the impact of Orai1 and STIM2 on melanoma cell proliferation, invasion, and phenotype.
• To explore the potential of targeting Orai1 and STIM2 for melanoma therapy.

Main Methods:

• Analysis of Orai1 and STIM2 expression in human melanoma cells and tissues.
• Manipulation of extracellular calcium levels and silencing of Orai1/STIM2 genes.
• Assessment of intracellular calcium levels, cell proliferation, migration, and expression of key melanoma markers (MITF, JARID1B, Brn2).
• Immunohistochemical staining of primary melanomas and lymph node metastases.

Main Results:

• Orai1 and STIM2 are highly expressed in human melanoma and regulate store-operated Ca2+ entry.
• Reduced intracellular Ca2+ due to lower extracellular Ca2+ or Orai1/STIM2 silencing enhanced melanoma cell proliferation and MITF expression.
• Silencing Orai1 and/or STIM2 decreased melanoma cell invasion and migration, correlating with reduced JARID1B and Brn2 expression.
• Orai1 and STIM2 showed heterogeneous expression in primary melanomas and metastases, with higher levels in the invasive tumor rim.

Conclusions:

• Orai1 and STIM2 inversely regulate melanoma growth and invasion, suggesting a dynamic role in tumor progression.
• Targeting Orai1 and STIM2, particularly STIM2, offers a potential therapeutic strategy to inhibit melanoma metastasis.
• Pharmacological modulation of Orai1 and STIM2 may enhance melanoma susceptibility to conventional anticancer therapies.