Second-generation testosterone-platinum(II) hybrids for site-specific treatment of androgen receptor positive prostate cancer: Design, synthesis and antiproliferative activity

Synthesis and anticancer properties of a hybrid molecule with the testosterone and estradiol head-groups

This is the first report on a unique hybrid molecule made of estradiol and testosterone (TS). This distinctive hybrid molecule (1) was designed to interact with both the estrogen receptor (ER) and the androgen receptor (AR) found in hormone-dependent female and male cancer cells, and was synthesized using ethynylestradiol (17EE) as the estrogenic component and 7α-(4-azido-but-2-enyl)-4-androsten-17β-ol-3-one as the androgenic counterpart in a seven-step reaction with ∼ 26 % overall yield. We reasoned that the dual receptor binding ability could allow 1 to act as an antihormone. This was tested on hormone-dependent and hormone-independent breast cancer (BCa) and prostate cancer (PCa) cells. The antiproliferative activity was also assessed on colon and skin cancer cells. We found that 1 was active against MCF7 (ER + ) BCa cells (IC50 of 4.9 μM), had lower inhibitory potency on LNCaP (AR + ) PCa cells (IC50 > 5 μM) and no effect on PC3 and DU145 (AR-) PCa cells. This suggests that the estrogenic component of 1 can interact with the ER on MCF7 cells more effectively than the androgenic component with the AR on LNCaP PCa cells, possibly due to a suboptimal spacer or linkage site(s). Nonetheless, the hybrid 1 was active against colon (HT-29) and melanoma (M21) cancer cells (IC50 of 3.5 μM and 2.3 μM, respectively), and had low cross-reactivity with the drug- and androgen-metabolizing cytochrome P450 3A4 (CYP3A4, IC50 ≫ 5 µM). These findings demonstrate the anticancer potential of 1 and warrant further explorations on this new type of hybrids.

Advancements in steroidal Pt(II) & Pt(IV) derivatives for targeted chemotherapy (2000-2023)

One of the key strategies in chemotherapy involves crosslinking the DNA strands of cancer cells to impede their replication, with platinum (Pt) coordination compounds being a prominent class and cisplatin being its major representative. Steroidal ligands tethered to DNA interactive Pt core act as drug carriers for targeted therapy. While crosslinking of nuclear or mitochondrial DNA strands using coordination complexes has been studied for years, there remains a lack of comprehensive reviews addressing the advancements made in steroidal-Pt derivatives. This review specifically focuses on advancements made in steroid-tethered structural derivatives of Pt(II) or prodrug Pt(IV) for targeted chemotherapy, synthesized between 2000 and 2023. This period was deliberately chosen due to the widespread use of computational techniques for more accurate structure-based drug-design in last two decades. This review discusses the strategy behind tethering steroidal ligands such as testosterone, estrogen, bile acids, and cholesterol to the central DNA interactive Pt core through specific linker groups. The steroidal ligands function as drug delivery vehicles of DNA interactive Pt core and bind with their respective target receptors or proteins that are often overexpressed in cancer cells, thus enabling targeted delivery of Pt moiety to interact with DNA. We discussed structural features such as the location of the linker group on the steroid, the mono, bi, and tridentate configuration of the chelating arm in coordination with Pt, and the rigidity and flexibility of the linker group. The comparative in vitro, in vivo activities, and relative binding affinities of the designed compounds against standard Pt drugs are also discussed. We also provided a critique of observed trends and shortcomings. Our review will provide insights into future molecular designing of targeted DNA crosslinkers and their structural optimization to achieve desired drug properties. From this analysis, we proposed further research directions leading to the future of targeted chemotherapy.

Targeting androgen receptor degradation with PROTACs from bench to bedside

Inhibition of androgen receptor (AR) has been extensively investigated to treat prostate cancer. Resistance mechanisms such as increased levels of androgen production, increased AR gene, enhancer expression and AR point mutations always reduce the clinical efficacy. Design and discovery of small-molecule PROTAC AR degraders have been pursued as a new therapeutic strategy to overcome common resistance mechanisms developed during prostate cancer treatment. In the last two decades, potent and efficacious PROTAC AR degraders have been gotten rapid development and several such compounds have been advanced into preclinical phase and phase I/II trials for the treatment of human prostate cancers. Especially, the first PROTAC to enter the clinic, ARV-110, has shown good clinical effects in patients with mCRPC. This fully demonstrates the high clinical value of PROTAC strategy in treatment of human diseases. Here, we summarized the recent advances in the development of these potential clinical-stage PROTAC AR degraders.

Recent Progresses in Conjugation with Bioactive Ligands to Improve the Anticancer Activity of Platinum Compounds

Platinum (Pt) drugs, including cisplatin, are widely used for the treatment of solid tumors. Despite the clinical success, side effects and occurrence of resistance represent major limitations to the use of clinically available Pt drugs. To overcome these problems, a variety of derivatives have been designed and synthetized. Here, we summarize the recent progress in the development of Pt(II) and Pt(IV) complexes with bioactive ligands. The development of Pt(II) and Pt(IV) complexes with targeting molecules, clinically available agents, and other bioactive molecules is an active field of research. Even if none of the reported Pt derivatives has been yet approved for clinical use, many of these compounds exhibit promising anticancer activities with an improved pharmacological profile. Thus, planning hybrid compounds can be considered as a promising approach to improve the available Pt-based anticancer agents and to obtain new molecular tools to deepen the knowledge of cancer progression and drug resistance mechanisms.

Rational design and synthesis of 6-aryl-6H-benzo[c]chromenes as non-steroidal progesterone receptor antagonists for use against cancers

Progesterone receptor (PR) antagonists have been found to be effective for treating certain human cancers. However, the steroidal structure of PR antagonists could bind to other hormone receptors, thus leading to serious side effects. On the other hand, non-steroidal PR antagonists have rarely been evaluated for their anti-cancer efficacy. Therefore, identifying novel non-steroidal PR antagonists possessing potent anti-cancer efficacy would be an attractive project to pursue. In this study, we presented a new metal-free oxidative CH arylation method to rapidly synthesize a series of 6-aryl-6H-benzo[c]chromene derivatives. Multiple cancer cell lines were used for their anti-cancer activity screening. An extensive analysis of structure-activity relationships (SAR) of the derivatives revealed that compounds 32 and 34 markedly inhibited the proliferation of MCF-7 cells with IC₅₀ values of 6.32 ± 0.52 μM and 5.71 ± 0.49 μM, respectively. Further investigation indicated that derivatives 32 and 34 could elevate the expression of p21 and decrease the expressions of CDK4 and cyclin D1, leading to cell cycle arrest at G0/G1 phase. In addition, derivatives 32 and 34 could induce apoptosis of MCF-7 cells in both dose- and time-dependent manners by activation of p53 pathway, i.e., activation of Cleaved Caspase-3, p53 and P-p53 as well as elevation of the Bax/Bcl-2 ratio. Docking of derivatives 32 and 34 into a PR homology model exhibited potent PR antagonistic activity indicating the 6-aryl-6H-benzo[c]chromene derivatives are promising PR antagonists. We envisioned that derivatives 32 and 34 might be potential anti-cancer drug candidates as novel therapeutic treatment for breast cancer.

Promising applications of steroid сonjugates for cancer research and treatment

The conjugation of biologically active molecules is a powerful tool for drug discovery used to target a variety of multifunctional diseases including cancer. Conjugated drugs can provide combination therapies in a single multi-functional agent and, by doing so, be more specific and powerful than conventional classic treatments. Steroids are widely used for conjugation with other biological active molecules. This review refers to investigations of steroid conjugates as potential anticancer agents carried out mostly over the past decade. It consists of five parts in which the data concerning structure and anticancer activity of steroid conjugates with DNA alkylating agents, metallocomplexes, approved drugs, some biological active molecules, some natural compounds and related synthetic analogs are described.