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Updated: Jan 15, 2026
Spatial and Temporal Control of Murine Melanoma Initiation from Mutant Melanocyte Stem Cells
Published on: June 7, 2019
Implications of melanogenesis stimulation in B16-F10 cells on the ubiquitin-proteasome system
Dainesy Santos Martins1, Marilene Demasi2, Daniel de Lima Bellan3
1Postgraduate Program in Biochemistry Sciences, Department of Biochemistry and Molecular Biology, Federal University of Paraná (UFPR), Curitiba, PR, Brazil.
Abstract:
The development of resistance by tumor cells is a challenge in cancer treatment; either in chemotherapy, immunotherapy and targeted therapy. Proteasome can be considered a promising therapeutic target, as it is considered the key to the ubiquitin-proteasome system (UPS), and is responsible for more than 80 % of cellular protein degradation. Considering that melanogenesis may be associated with melanoma resistance to treatments, this study aimed to investigate the response of melanoma cells with or without stimulation of melanogenesis against treatment with UPS inhibitors. We used murine melanoma cell line, B16-F10 with and without stimulation of melanogenesis. We investigated cell responses after treatments with UPS inhibitors BTZ or PYZD-4409. In melanogenesis-stimulated B16-F10, cells we observed resistance to the treatment with BTZ, with a decrease in the inhibition of proteasome, which attenuated the effects on cell viability and apoptosis. However, BTZ treatment in B16-F10 murine melanoma cells promoted proteasome inhibition, reduced percentage of viable cells and increased active caspase-3, causing cell death by apoptosis. In turn, in the inhibition of the ubiquitination process at E1 (first enzyme in the ubiquitination process) by the compound PYZD-4409, the stimulus of melanogenesis did not prevent the reduction in the percentage of metabolically active cells, decrease in percentage of adhered cells and induction of cell death by apoptosis. This study indicates that inhibition of protein ubiquitination would be an important alternative for the treatment of melanoma, however not by the inhibitors of the proteasome such as BTZ, especially in highly melanogenic tumors.
Insights
Melanoma cells resistant to proteasome inhibitors like BTZ can be overcome by targeting the ubiquitination process. Inhibiting E1 enzyme with PYZD-4409 effectively induces apoptosis in melanoma cells, offering a promising therapeutic strategy.
Area of Science:
- Oncology
- Molecular Biology
- Biochemistry
Background:
- Tumor cell resistance to cancer therapies (chemotherapy, immunotherapy, targeted therapy) is a significant clinical challenge.
- The ubiquitin-proteasome system (UPS) is crucial for cellular protein degradation, making the proteasome a promising therapeutic target.
- Melanogenesis, the process of melanin production, may be linked to melanoma's resistance to cancer treatments.
Purpose of the Study:
- To investigate the response of melanoma cells, with and without melanogenesis stimulation, to ubiquitin-proteasome system (UPS) inhibitors.
- To evaluate the efficacy of proteasome inhibitors (BTZ) and E1 ubiquitination inhibitors (PYZD-4409) in melanoma models with varying melanogenesis activity.
Main Methods:
- Utilized the murine melanoma cell line B16-F10, with and without stimulated melanogenesis.
- Administered UPS inhibitors Bortezomib (BTZ) and PYZD-4409 to assess cell viability, apoptosis, and proteasome inhibition.
- Quantified cell viability, adherence, and apoptosis markers (active caspase-3).
Main Results:
- Melanogenesis-stimulated B16-F10 cells exhibited resistance to BTZ, with reduced proteasome inhibition and attenuated effects on cell viability and apoptosis.
- BTZ treatment in non-stimulated B16-F10 cells effectively inhibited the proteasome, reduced cell viability, and induced apoptosis.
- PYZD-4409 treatment, inhibiting the E1 enzyme in ubiquitination, reduced cell viability and induced apoptosis regardless of melanogenesis stimulation.
Conclusions:
- Inhibition of protein ubiquitination, rather than proteasome inhibition, presents a viable alternative for melanoma treatment, particularly for highly melanogenic tumors.
- Proteasome inhibitors like BTZ may be less effective in melanogenesis-stimulated melanoma due to acquired resistance.
- Targeting the initial steps of the ubiquitination pathway offers a promising strategy to overcome treatment resistance in melanoma.
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