Radiosynthesis and pharmacokinetics of [18F]fluoroethyl bufalin in hepatocellular carcinoma-bearing mice

Development of 18F-Labeled Positron Emission Tomography Agents Targeting Fibroblast Activation Protein

Fibroblast activation protein (FAP) is expressed in activated fibroblasts but not in quiescent fibroblasts. Thus, it allows us to use this membrane-anchored enzyme as a target for radionuclide-based tumor diagnosis and treatment and the diagnosis of nonmalignant diseases. In this report, we synthesized and evaluated a series of 18F-labeled FAP inhibitors (FAPIs), aiming to obtain PET agents with good in vivo distribution and tumor specificity. These 18F-labeled arene- and aliphatic-vinyl sulfones were prepared with yields of 52.3-78.6%, which were then reacted with FAPIs to obtain corresponding imaging agents with yields of 47.3-88.7% (2nd step). When tested in the U87MG tumor-bearing mice, [18F]11 exhibited 8.2 ± 0.9%ID/g tumor uptake at 0.5 h p.i. with relatively low muscle uptake (T/M ratio of 10.5). In the presence of FAPI inhibitor SP-13786, the tumor uptake of [18F]11 was successfully reduced to 1.4%ID/g, confirming the receptor specificity of this agent. Autoradiography and immunohistochemical staining analysis revealed similar tumor distribution patterns of [18F]11 and FAP+ cells in U87MG tumor tissues. Our findings suggest that [18F]11 demonstrates great potential as an FAP-targeted PET agent for tumor detection and can be further evaluated in the future.

Metal phenolic networks-driven bufalin homodimeric prodrug nano-coassemblies for ferroptosis-augmented tumor therapy

Poor bioavailability and dose-limiting cardiotoxicity persistently hinder the clinical application of bufalin (BF). Conventional BF-based nanoagents have shown promise in tackling these challenges, yet advanced nanostrategies with further improved performance and clinical accessibility still await development. Herein, we introduce a novel cooperative nanoparadigm based on disulfide-linked BF homodimeric prodrugs (SBF) and metal-phenolic networks (MPNs). This strategy achieves high drug-loading capacity and structural stability. Stability perturbation experiments reveal that hydrophobic interactions, electrostatic adsorption, and coordination bonds synergistically drive co-assembly of SBF and MPNs. The resultant nanopartieles (MSBNAs) exhibit prolonged circulation kinetics, tumor-selective accumulation, and pH/GSH dual-responsive properties, effectively mitigating BF-induced cardiotoxicity. Further antitumor mechanistic investigations unveil that MSBNAs amplify BF-induced ferroptosis through a dual assault of oxidative stress and iron overload induced jointly by MPNs-delivered exogenous iron and BF-triggered endogenous iron. This increased ferroptosis endows MSBNAs with superior suppression of tumor growth and lung metastasis, maintaining excellent biocompatibility without cardiotoxicity. Our work not only establishes a promising candidate platform to surmount the therapeutic hurdles of BF but also enriches the design landscapes of co-assembled nanomedicines, thereby laying a foundation for the clinical translation of BF and other antitumor drugs.

Bufalin CaCO3 Nanoparticles Triggered Pyroptosis through Calcium Overload via Na+/Ca2+ Exchanger Reverse for Cancer Immunotherapy

Bufalin is a promising active ingredient in traditional Chinese medicine but has shown limited anticancer applications due to its toxicity. Here, we report BCNPs@gel, a bufalin-containing CaCO3 nanoparticle hydrogel, for enhancing cancer treatment through inducing cellular pyroptosis. Under the tumor microenvironment's low pH conditions, bufalin and Ca2+ are released from the delivery system. Bufalin serves as a direct anticancer drug and a Na+/K+-ATPase inhibitor by forcing the Na+/Ca2+ exchanger to reverse its function, which transfers Ca2+ into cytoplasm and ultimately causes Ca2+ overload-triggered pyroptosis. Meanwhile, we found that bufalin can upregulate PD-L1 in tumor cells. In combination with the PD-1 antibody, the delivery system showed a greater performance during the cancer treatment. BCNPs@gel enhances antitumor efficiency, reduces systemic side effects, extends antitumor mechanism of bufalin, and provides new strategies for inducing pyroptosis and calcium overload in cancer immunotherapy via Na+/K+-ATPase inhibitor. This work provides an application model for numerous other traditional Chinese medicine ingredients.

Bufalin for an innovative therapeutic approach against cancer

Bufalin is an endogenous cardiotonic steroid, first discovered in toad venom but also found in the plasma of healthy humans, with anti-tumour activities in different cancer types. The current review is focused on its mechanisms of action and highlights its very large spectrum of effects both in vitro and in vivo. All leads to the conclusion that bufalin mediates its effects by affecting all the hallmarks of cancer and seems restricted to cancer cells avoiding side effects. Bufalin decreases cancer cell proliferation by acting on the cell cycle and inducing different mechanisms of cell death including apoptosis, necroptosis, autophagy and senescence. Bufalin also moderates metastasis formation by blocking migration and invasion as well as angiogenesis and by inducing a phenotype switch towards differentiation and decreasing cancer cell stemness. Regarding its various mechanisms of action in cancer cells, bufalin blocks overactivated signalling pathways and modifies cell metabolism. Moreover, bufalin gained lately a huge interest in the field of drug resistance by both reversing various drug resistance mechanisms and affecting the immune microenvironment. Together, these data support bufalin as a quite promising new anti-cancer drug candidate.

Tumor-Targeted Delivery of Bufalin-Loaded Modified Albumin-Polymer Hybrid for Enhanced Antitumor Therapy and Attenuated Hemolysis Toxicity and Cardiotoxicity

A novel albumin polymer hybrid with a core-shell structure was designed to target delivery of bufalin, which is an antineoplastic monomer with serious cardiotoxicity. The sheath layer was composed of ursodeoxycholic acid (UA)-modified bovine serum albumin (UA-BSA), while the stable core consisted of poly n-butyl cyanoacrylate (PBCA) nanoparticles. The UA-BSA was synthetized, and the substitution degree was characterized. The physical properties of bufalin-loaded UA-modified protein-PBCA nanocomplexes (BF-uPPNCs), such as morphology, particle size, and encapsulation efficiency, were evaluated. FTIR and DSC revealed the bufalin to be in an amorphous state. Furthermore, the in vitro release study indicated a sustained release profile of BF-uPPNCs. The MTT and cellular uptake study demonstrated that BF-uPPNCs significantly improved the inhibitory effect of the bufalin accompanied with an enhanced cell uptake capacity on HepG2 cells. In addition, in vivo research demonstrated that BF-uPPNCs had a better antitumor effect coupled with improved therapeutic effect, and reduced hemolysis, vascular irritation, and cardiotoxicity. This work therefore presented a novel albumin polymer hybrid with favorable stability, efficient tumor-targeted delivery potential, and side effect reduction ability, which can be a potential vehicle for an anticancer drug.

Noninvasive Imaging for Assessment of the Efficacy of Therapeutic Agents for Hepatocellular Carcinoma

Morphological imaging techniques are typically used in the anti-cancer drug efficacy evaluation process. However, these techniques can evaluate the therapeutic efficacy only when the tumor shows anatomic changes-usually at later stages, when the therapeutic effects are poor. In contrast, molecular imaging allows noninvasive monitoring of tumor growth, assessment of drug metabolism, and evaluation of therapeutic efficacy at the molecular and cellular levels. Multimodality molecular imaging, which combines the advantages of various imaging modalities, provides even more comprehensive therapeutic efficacy assessment in preclinical and clinical studies. This review provides an overview of molecular imaging evaluation of therapeutic efficacy of the anti-tumor drugs in hepatocellular carcinoma (HCC) both in preclinical and clinical research, which holds great promise in guiding HCC treatment into the era of precision medicine.

New therapeutic aspects of steroidal cardiac glycosides: the anticancer properties of Huachansu and its main active constituent Bufalin

Aim of the review

In the past decade, increasing research attention investigated the novel therapeutic potential of steroidal cardiac glycosides in cancer treatment. Huachansu and its main active constituent Bufalin have been studied in vitro, in vivo and clinical studies. This review aims to summarize the multi-target and multi-pathway pharmacological effects of Bufalin and Huachansu in the last decade, with the aim of providing a more comprehensive view and highlighting the recently discovered molecular mechanisms.

Results

Huachansu and its major derivative, Bufalin, had been found to possess anti-cancer effects in a variety of cancer cell lines both in vitro and in vivo. The underlying anti-cancer molecular mechanisms mainly involved anti-proliferation, apoptosis induction, anti-metastasis, anti-angiogenesis, epithelial-mesenchymal transition inhibition, anti-inflammation, Na⁺/K⁺-ATPase activity targeting, the steroid receptor coactivator family inhibitions, etc. Moreover, the potential side-effects and toxicities of the toad extract, Huachansu, and Bufalin, including hematological, gastrointestinal, mucocutaneous and cardiovascular adverse reactions, were reported in animal studies and clinic trails.

Conclusions

Further research is needed to elucidate the potential drug-drug interactions and multi-target interaction of Bufalin and Huachansu. Large-scale clinical trials are warranted to translate the knowledge of the anticancer actions of Bufalin and Huachansu into clinical applications as effective and safe treatment options for cancer patients in the future.