Estradiol dimers (EDs) possess significant anticancer activity by targeting tubulin dynamics. In this study, we synthesised 12 EDs variants via copper-catalysed azide-alkyne cycloaddition (CuAAC) reaction, focusing on structural modifications within the aromatic bridge connecting two estradiol moieties. In vitro testing of these EDs revealed a marked improvement in selectivity towards cancerous cells, particularly for ED1-8. The most active compounds, ED3 (IC50 = 0.38 μM in CCRF-CEM) and ED5 (IC50 = 0.71 μM in CCRF-CEM) demonstrated cytotoxic effects superior to 2-methoxyestradiol (IC50 = 1.61 μM in CCRF-CEM) and exhibited anti-angiogenic properties in an endothelial cell tube-formation model. Cell-based experiments and in vitro assays revealed that EDs interfere with mitotic spindle assembly. Additionally, we proposed an in silico model illustrating the probable binding modes of ED3 and ED5, suggesting that dimers with a simple linker and a single substituent on the aromatic central ring possess enhanced characteristics compared to more complex dimers.

• Keywords
• Estradiol, cancer cell, dimer, in silico, tubulin,
• MeSH
• Click Chemistry MeSH
• Dimerization MeSH
• Estradiol * pharmacology   chemistry   chemical synthesis   MeSH
• Humans MeSH
• Molecular Structure MeSH
• Cell Line, Tumor MeSH
• Cell Proliferation * drug effects   MeSH
• Antineoplastic Agents * pharmacology   chemical synthesis   chemistry   MeSH
• Drug Screening Assays, Antitumor * MeSH
• Dose-Response Relationship, Drug * MeSH
• Structure-Activity Relationship MeSH
• Check Tag
• Humans MeSH
• Publication type
• Journal Article MeSH
• Names of Substances
• Estradiol * MeSH
• Antineoplastic Agents * MeSH

We tested the effect of substituents at the (1) C3´, C3´N, (2) C10, and (3) C2-meta-benzoate positions of taxane derivatives on their activity against sensitive versus counterpart paclitaxel-resistant breast (MCF-7) and ovarian (SK-OV-3) cancer cells. We found that (1) non-aromatic groups at both C3´ and C3´N positions, when compared with phenyl groups at the same positions of a taxane derivative, significantly reduced the resistance of ABCB1 expressing MCF-7/PacR and SK-OV-3/PacR cancer cells. This is, at least in the case of the SB-T-1216 series, accompanied by an ineffective decrease of intracellular levels in MCF-7/PacR cells. The low binding affinity of SB-T-1216 in the ABCB1 binding cavity can elucidate these effects. (2) Cyclopropanecarbonyl group at the C10 position, when compared with the H atom, seems to increase the potency and capability of the derivative in overcoming paclitaxel resistance in both models. (3) Derivatives with fluorine and methyl substituents at the C2-meta-benzoate position were variously potent against sensitive and resistant cancer cells. All C2 derivatives were less capable of overcoming acquired resistance to paclitaxel in vitro than non-substituted analogs. Notably, fluorine derivatives SB-T-121205 and 121,206 were more potent against sensitive and resistant SK-OV-3 cells, and derivatives SB-T-121405 and 121,406 were more potent against sensitive and resistant MCF-7 cells. (4) The various structure-activity relationships of SB-T derivatives observed in two cell line models known to express ABCB1 favor their complex interaction not based solely on ABCB1.

• Keywords
• C10 taxane derivatives, C2 taxane derivatives, C3´ and C3´N taxane derivatives, Resistant breast cancer cells, Resistant ovarian cancer cells,
• MeSH
• Benzoates pharmacology   chemistry   MeSH
• Drug Resistance, Neoplasm * drug effects   MeSH
• Humans MeSH
• MCF-7 Cells MeSH
• Cell Line, Tumor MeSH
• Breast Neoplasms drug therapy   pathology   MeSH
• Ovarian Neoplasms drug therapy   pathology   MeSH
• ATP Binding Cassette Transporter, Subfamily B * metabolism   genetics   MeSH
• Paclitaxel pharmacology   MeSH
• Antineoplastic Agents pharmacology   chemistry   MeSH
• Taxoids pharmacology   chemistry   MeSH
• Structure-Activity Relationship MeSH
• Check Tag
• Humans MeSH
• Female MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH
• Research Support, N.I.H., Extramural MeSH
• Names of Substances
• ABCB1 protein, human MeSH Browser
• Benzoates MeSH
• ATP Binding Cassette Transporter, Subfamily B * MeSH
• Paclitaxel MeSH
• Antineoplastic Agents MeSH
• Taxoids MeSH

The ability of cells to switch between different invasive modes during metastasis, also known as invasion plasticity, is an important characteristic of tumor cells that makes them able to resist treatment targeted to a particular invasion mode. Due to the rapid changes in cell morphology during the transition between mesenchymal and amoeboid invasion, it is evident that this process requires remodeling of the cytoskeleton. Although the role of the actin cytoskeleton in cell invasion and plasticity is already quite well described, the contribution of microtubules is not yet fully clarified. It is not easy to infer whether destabilization of microtubules leads to higher invasiveness or the opposite since the complex microtubular network acts differently in diverse invasive modes. While mesenchymal migration typically requires microtubules at the leading edge of migrating cells to stabilize protrusions and form adhesive structures, amoeboid invasion is possible even in the absence of long, stable microtubules, albeit there are also cases of amoeboid cells where microtubules contribute to effective migration. Moreover, complex crosstalk of microtubules with other cytoskeletal networks participates in invasion regulation. Altogether, microtubules play an important role in tumor cell plasticity and can be therefore targeted to affect not only cell proliferation but also invasive properties of migrating cells.

• Keywords
• 3D migration, amoeboid, cancer, invasion plasticity, mesenchymal, microtubules,
• Publication type
• Journal Article MeSH
• Review MeSH