Synthesis of novel flexible tamoxifen analogues to overcome CYP2D6 polymorphism and their biological evaluation on MCF-7 cell line

In Vitro Evaluation of Endocrine-Related Adverse Effects of 5-Fluoroindole Derived Melatonin Analogues with Antioxidant Activity

Melatonin (MLT) is a natural indolic hormone with well documented antioxidant properties, but it can also modulate the estrogen signaling pathway by inhibiting the aromatase enzyme and estrogen receptor modulating activity. This dual activity raises concerns about potential endocrine-related adverse effects when using MLT and its analogues as therapeutic agents in the prevention and treatment of oxidative stress related diseases. In this study, 34 novel 5-fluoroindole derivatives of MLT were synthesized and evaluated for their antioxidant, estrogen receptor modulatory, and aromatase inhibitory activities.Three compounds (4c, 5c, and 6c) demonstrated significant antioxidant activity, with compound 4c showing the highest efficacy in reducing intracellular reactive oxygen species (ROS) by 65 % in CHO-K1 cells and displaying DPPH radical scavenging comparable to the standard antioxidant, BHT. However, these same compounds also exhibited antiestrogenic effects in the E-Screen assay, with IC50 values of 3.36×10-5 M, 1.31×10-7 M, and 1.9×10-7 M, respectively, and inhibited aromatase activity by up to 29 % in a direct enzymatic assay. These findings indicate that, while the compounds have potent antioxidant properties, their significant antiestrogenic and aromatase inhibitory activities may pose risks for unintended endocrine related effects. Further studies are needed to better understand the implications of these activities in vivo and to balance the benefits and risks of such compounds in therapeutic applications.

Oestrogen receptor positive breast cancer and its embedded mechanism: breast cancer resistance to conventional drugs and related therapies, a review

Traditional medication and alternative therapies have long been used to treat breast cancer. One of the main problems with current treatments is that there is an increase in drug resistance in the cancer cells owing to genetic differences such as mutational changes, epigenetic changes and miRNA (microRNA) alterations such as miR-1246, miR-298, miR-27b and miR-33a, along with epigenetic modifications, such as Histone3 acetylation and CCCTC-Binding Factor (CTCF) hypermethylation for drug resistance in breast cancer cell lines. Certain forms of conventional drug resistance have been linked to genetic changes in genes such as ABCB1, AKT, S100A8/A9, TAGLN2 and NPM. This review aims to explore the current approaches to counter breast cancer, the action mechanism, along with novel therapeutic methods endowing potential drug resistance. The investigation of novel therapeutic approaches sheds light on the phenomenon of drug resistance including genetic variations that impact distinct forms of oestrogen receptor (ER) cancer, genetic changes, epigenetics-reported resistance and their identification in patients. Long-term effective therapy for breast cancer includes selective oestrogen receptor modulators, selective oestrogen receptor degraders and genetic variations, such as mutations in nuclear genes, epigenetic modifications and miRNA alterations in target proteins. Novel research addressing combinational therapies including maytansine, photodynamic therapy, guajadiol, talazoparib, COX2 inhibitors and miRNA 1246 inhibitors have been developed to improve patient survival rates.

Design, synthesis, and in-silico study of novel triarylethylene analogs with dual anti-estrogenic and serotonergic activity

Estrogen receptor is an important target in breast cancer. Serotonin receptors (5-HT2A and 5-HT2C , in particular) were investigated for a potential role in development and progression of breast cancer. Ligands that interact with estrogenic receptors influence the emotional state of females. Thus, designing selective estrogen receptor modulator (SERM) analogs with potential serotonergic activity is a plausible approach. The dual ligands can augment cytotoxic effect of SERMs, help in both physical and emotional menopausal symptom relief, enhance cognitive function and support bone health. Herein, we report triarylethylene analogs as potential candidates for treatment of breast cancer. Compound 2e showed (ERα relative β- galactosidase activity = 0.70), 5-HT2A (Ki  = 0.97 µM), and 5-HT2C (Ki  = 3.86 µM). It was more potent on both MCF-7 (GI50  = 0.27 µM) and on MDA-MB-231 (GI50  = 1.86 µM) compared to tamoxifen (TAM). Compound 4e showed 40 times higher antiproliferative activity on MCF-7 and 15 times on MDA-MBA compared to TAM. Compound 4e had higher average potency than TAM on all nine tested cell line panels. Our in-silico model revealed the binding interactions of compounds 2 and 2e in the three receptors; further structural modifications are suggested to optimize binding to the ERα, 5-HT2A , and 5-HT2C .

The mechanisms of multidrug resistance of breast cancer and research progress on related reversal agents

Chemotherapy is the mainstay in the treatment of breast cancer. However, many drugs that are commonly used in clinical practice have a high incidence of side effects and multidrug resistance (MDR), which is mainly caused by overexpression of drug transporters and related enzymes in breast cancer cells. In recent years, researchers have been working hard to find newer and safer drugs to overcome MDR in breast cancer. In this review, we provide the molecule mechanism of MDR in breast cancer, categorize potential lead compounds that inhibit single or multiple drug transporter proteins, as well as related enzymes. Additionally, we have summarized the structure-activity relationship (SAR) based on potential breast cancer MDR modulators with lower side effects. The development of novel approaches to suppress MDR is also addressed. These lead compounds hold great promise for exploring effective chemotherapy agents to overcome MDR, providing opportunities for curing breast cancer in the future.

Structure-Activity Relationships of Triphenylethylene Derivatives and Their Evaluation as Anticancer and Antiviral Agents

Tamoxifen (TAM) is a selective estrogen receptor modulator (SERM) that is used in the treatment of breast cancer, yet with the risk of developing uterine cancer. A perfect SERM would act as an estrogen activator on bones, the cardiovascular system, and the central nervous system while providing neutral or estrogen blocking effects on the breast and the uterus. Herein, we report on the design, synthesis, and evaluation of new rigid and flexible TAM analogues. Mainly, a chloro substituent is introduced at the para position of the TAM ring C blocking the CYP2D6 hydroxylation site. Most compounds showed estrogenic activity higher than TAM using the yeast estrogen screen assays, indicating the determinant role of the chloro substituent upon functional activity. Despite being estrogenic, compound 2B showed potent antiproliferative activity in the NCI 60 cell lines with mean GI₅₀ = 3.67 μM, GI₅₀ = 1.05 μM on MCF-7 cell lines, and GI₅₀ = 1.30 μM on MDA-MB-231. The estrogenic activity of compound 2B was further confirmed by stimulating alkaline phosphatase in Ishikawa cells, and it showed no increase in relative uterine wet weight in ovariectomized rats. Compound 2F showed EC₉₀ = 0.31 μg/mL and SI₉₀ = 60 against Ebola virus; this is 200-fold more potent than the positive control favipiravir. This is the first time to report estrogenic triphenylethylenes as anti-EBOV agents. The anti-EBOV activity reported is a function of the substitution pattern of the scaffold rather than the functional activity. Moreover, compound 3D showed excellent PO pharmacokinetic properties in mice. In conclusion, for this class of TAM-like compounds, the blockage of the p-position of ring C is decisive for the functional activity; meanwhile, the triarylethylene substitution pattern is detrimental for the antiviral activity.

Tamoxifen and oxidative stress: an overlooked connection

Tamoxifen is the gold standard drug for the treatment of breast cancer in pre and post-menopausal women. Its journey from a failing contraceptive to a blockbuster is an example of pharmaceutical innovation challenges. Tamoxifen has a wide range of pharmacological activities; a drug that was initially thought to work via a simple Estrogen receptor (ER) mechanism was proven to mediate its activity through several non-ER mechanisms. Here in we review the previous literature describing ER and non-ER targets of tamoxifen, we highlighted the overlooked connection between tamoxifen, tamoxifen apoptotic effects and oxidative stress.

Novel Carbamοyloxy Analogues of Tamoxifen: Synthesis, Molecular Docking and Bioactivity Evaluation

Background:

Tamoxifen (TAM), a non-steroidal antiestrogen, constitutes the endocrine treatment of choice against breast cancer. Since its inauguration, substantial effort has been devoted towards the design and synthesis of TAM’s analogues aiming to improve its bioactivity and reveal their structure-activity relationship.

Objective:

One of the most studied synthetic features of TAM’s structure is the ether side chain, which is strongly related to its positioning into the active site of the Estrogen Receptors (ERα and ERβ). Herein, we present the application of a straightforward route for the efficient synthesis of selected novel carbamoyloxy analogues of TAM and the evaluation of their respective binding affinities to the Estrogen Receptors α and β.

Methods:

A one-pot reaction was applied for the construction of TAM’s triarylethylene core moiety, which subsequently was derivatized to provide efficiently the target carbamoyloxy analogues of TAM. The Z and E isomers of the latter were separated using RP-HPLC-UV and their binding affinities to ERα and ERβ were measured.

Results:

Among all compounds synthesized, the dimethyl derivative was determined as the most potent for both receptors, displaying binding affinity values comparable to TAM, though the Zdiethyl analogue maintained substantial affinity to both ERs. The aforementioned results were further studied by theoretical calculations and molecular modelling to delineate a concordance among calculations and biological activity.

Conclusion:

Approach applied herein permitted the extraction of a useful structure-activity relationship correlation pattern highlighting the importance of a chemically stabilized tamoxifen side chain.