Milo-Rocha Edgar, Díaz Lorenza, García-Quiroz Janice, Prado-Garcia Heriberto, García-Becerra Rocío
Departamento de Biología Molecular y Biotecnología, Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México, Ciudad de México 04510, Mexico.
Departamento de Biología de la Reproducción Dr. Carlos Gual Castro, Instituto Nacional de Ciencias Médicas y Nutrición Salvador Zubirán, Vasco de Quiroga No. 15, Belisario Domínguez Sección XVI, Tlalpan, Ciudad de México 14080, Mexico.
Int J Mol Sci. 2025 Aug 29;26(17):8396. doi: 10.3390/ijms26178396.
HER2-positive breast cancer is an aggressive subtype, often associated with shorter progression-free and overall survival. Estrogen receptor (ER) expression within this subtype leads to distinct growth patterns and treatment responses. Calcitriol, the active form of vitamin D, induces ERα expression in ER-negative breast cancer cells, thereby sensitizing them to the antiproliferative effects of antiestrogens. When combined with neratinib, calcitriol enhanced cell growth inhibition. Therefore, we investigated whether adding calcitriol to the combined treatment with antiestrogens and neratinib could further inhibit the proliferation of HER2-positive breast cancer cells, regardless of their ER status. The BT-474 (ER-positive/HER2-positive) and SK-BR-3 (ER-negative/HER2-positive) breast cancer cell lines were pretreated with calcitriol to modulate ER expression, followed by treatment with calcitriol in combination with neratinib, with or without antiestrogens. Proliferation assays, cell cycle analysis, and Western blotting were then performed to assess treatment effects. The results demonstrated that calcitriol and neratinib, per se, significantly inhibited cell proliferation in a concentration-dependent manner in the HER2-positive cell lines. Notably, calcitriol enhanced the antiproliferative response of combined neratinib and antiestrogen treatment. Calcitriol, alone or in combination, modulated vitamin D receptor and ERα expression, reduced AKT and ERK phosphorylation, and promoted G1 phase arrest. These findings support the potential of this combinatorial approach as a therapeutic strategy for HER2-positive breast cancer.
人表皮生长因子受体2（HER2）阳性乳腺癌是一种侵袭性亚型，常与较短的无进展生存期和总生存期相关。该亚型内的雌激素受体（ER）表达导致不同的生长模式和治疗反应。骨化三醇是维生素D的活性形式，可诱导ER阴性乳腺癌细胞中ERα的表达，从而使它们对抗雌激素的抗增殖作用敏感。当与奈拉替尼联合使用时，骨化三醇增强了细胞生长抑制作用。因此，我们研究了在抗雌激素和奈拉替尼联合治疗中添加骨化三醇是否能进一步抑制HER2阳性乳腺癌细胞的增殖，无论其ER状态如何。用骨化三醇预处理BT-474（ER阳性/HER2阳性）和SK-BR-3（ER阴性/HER2阳性）乳腺癌细胞系以调节ER表达，然后将骨化三醇与奈拉替尼联合使用，同时或不使用抗雌激素进行处理。随后进行增殖测定、细胞周期分析和蛋白质印迹以评估治疗效果。结果表明，骨化三醇和奈拉替尼本身在HER2阳性细胞系中以浓度依赖性方式显著抑制细胞增殖。值得注意的是，骨化三醇增强了奈拉替尼和抗雌激素联合治疗的抗增殖反应。骨化三醇单独或联合使用时，可调节维生素D受体和ERα的表达，降低AKT和ERK磷酸化，并促进G1期阻滞。这些发现支持了这种联合方法作为HER2阳性乳腺癌治疗策略的潜力。
