Development of a Doxorubicin Resistance Model in HER2- and HER2+ Breast Cancer to Analyze Potential Therapy Targets
Sara Molenda1,2,3, Katarzyna Gryska1,2, Igor Piotrowski4
1Department of Cancer Immunology, Poznan University of Medical Sciences, 60-806 Poznan, Poland.
Abstract:
Despite the development of new drugs, chemoresistance constitutes a major obstacle in cancer treatment. To investigate mechanisms of resistance and potential therapeutic targets, we developed doxorubicin-resistant models of HER2- (D2F2/Dox) and HER2+ (D2F2E2/Dox) breast cancer cells. Compared with parental cells, the D2F2/Dox and D2F2E2/Dox differed in morphology, increased migratory potential, elevated levels of the transcription factor signal transducer and activator of transcription 3 (Stat3), and a lower proliferation rate in D2F2E2/Dox. Moreover, D2F2/Dox and D2F2E2/Dox differed in the expression profiles of genes related to cell stemness, apoptosis, and drug efflux. Stat3 gene silencing in both doxorubicin-resistant cell types reversed the expression profiles of some genes (different in each resistant cell line), and decreased migratory potential was observed only in D2F2 cells. These data indicate that the acquired doxorubicin resistance was associated with Stat3 status; however, HER2- and HER2+ breast cancer cells did not indicate the same mechanism of chemoresistance acquisition. Importantly, Stat3 silencing did not substantially restore doxorubicin sensitivity, suggesting that effective therapy may require simultaneous targeting of multiple pathways. Furthermore, we demonstrated that siStat3 therapeutics could be selectively delivered to HER2+ cancer cells using H2.1MS1:MS2KN silk spheres, indicating their potential for targeted drug delivery in vivo.
Insights
Chemoresistance in breast cancer is complex. Targeting signal transducer and activator of transcription 3 (Stat3) alone is insufficient, but Stat3-targeted silk spheres show potential for HER2+ cancer drug delivery.
Area of Science:
- Oncology
- Molecular Biology
- Cancer Research
Background:
- Chemoresistance remains a significant challenge in breast cancer treatment, hindering therapeutic efficacy.
- Understanding the molecular mechanisms underlying acquired chemoresistance is crucial for developing effective treatment strategies.
Purpose of the Study:
- To investigate the mechanisms of doxorubicin resistance in HER2-negative and HER2-positive breast cancer cells.
- To explore the role of signal transducer and activator of transcription 3 (Stat3) in chemoresistance and identify potential therapeutic targets.
Main Methods:
- Development of doxorubicin-resistant models (D2F2/Dox and D2F2E2/Dox) from HER2- and HER2+ breast cancer cells.
- Analysis of cellular morphology, migratory potential, proliferation rates, and gene expression profiles.
- Gene silencing of Stat3 using siRNA and assessment of its effects on chemoresistance and migratory potential.
- Evaluation of targeted delivery of Stat3-silencing therapeutics using silk spheres.
Main Results:
- Doxorubicin-resistant cells exhibited altered morphology, increased migration, elevated Stat3 levels, and differential gene expression related to stemness, apoptosis, and drug efflux.
- Stat3 silencing partially reversed gene expression changes and reduced migration in HER2-negative cells but did not restore doxorubicin sensitivity.
- HER2+ cancer cells demonstrated potential for selective delivery of Stat3-silencing therapeutics via silk spheres.
Conclusions:
- Acquired doxorubicin resistance is associated with Stat3 status, but mechanisms differ between HER2-negative and HER2-positive breast cancer cells.
- Stat3 is not a sole determinant of chemoresistance, suggesting combination therapies are necessary.
- Silk sphere-based delivery systems show promise for targeted Stat3 inhibition in HER2-positive breast cancer.
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