Protein Kinase C Inhibition Overcomes Targeted Therapy Resistance in Cutaneous Melanoma

Area of Science:

• Oncology
• Molecular Biology
• Dermatology

Background:

• WNT5a expression correlates with MAPK inhibitor resistance in melanoma, promoting cell polarity and invasion.
• No specific small molecules targeting WNT5a are currently available.
• Previous studies showed success with pan-protein kinase C (PKC) inhibitors in targeting WNT5a-dependent WNT signaling in uveal melanoma.

Purpose of the Study:

• To investigate the relevance of PKC inhibition in cutaneous melanoma.
• To explore the potential of combining PKC and mitogen-activated protein kinase (MAPK) pathway inhibition for treating therapy-resistant melanoma.

Main Methods:

• Investigated the association between PKC signaling and WNT5a expression in cutaneous melanoma.
• Evaluated the efficacy of pan-PKC inhibitors, alone and in combination with MAPK pathway inhibitors, in vitro and in vivo xenograft models.
• Assessed proliferation, invasion, and apoptosis induction as key outcome measures.

Main Results:

• A positive feedback loop between PKC signaling and WNT5a expression was identified, suggesting pan-PKC inhibitors can target WNT5a in cutaneous melanoma.
• Combinatorial PKC and MAPK pathway inhibition significantly reduced melanoma cell proliferation and invasion in vitro by inducing apoptosis.
• In vivo xenograft studies showed reduced proliferation and increased apoptosis with single and combination PKC inhibitor treatments compared to standard care.

Conclusions:

• Targeting the non-canonical WNT signaling pathway through combined PKC and MAPK inhibition is a promising strategy for therapy-resistant cutaneous melanoma.
• This combinatorial approach effectively combats tumor heterogeneity in vivo.
• The study proposes this strategy as a potential alternative for future clinical interventions in cutaneous melanoma.