Advances in traditional Chinese herbal medicine and their pharmacodynamic mechanisms in cancer immunoregulation: a narrative review.

Background and Objective: The cancer-immunity cycle (CIC) is defined as a series of progressive events that cause an anticancer immune response leading to the killing of the cancer cell. The concept of CIC has important guiding significance for the clinical and basic tumor immunotherapy research. As one of the methods of traditional Chinese medicine (TCM), Chinese herbal medicine (CHM) has shown unique advantages in multitarget and multipathway immune regulation. However, the tumor immune circulation targeted by CHM is generally unclear at present. To provide reference for future clinical and basic research, we systematically reviewed the existing literature on CHM (including CHM monomers, CHM compounds, and CHM patent medicines) and the mechanisms related to its efficacy. Methods: We searched the PubMed and China National Knowledge Infrastructure (CNKI) databases for relevant Chinese-language and English-language literature published from January 1988 to October 2022. The literature was screened manually at three levels: title, abstract, and full text, to identify articles related to CHM and their mechanism of regulating tumor immunity. Key Content and Findings: By further classifying the CIC, it was confirmed that CHM can regulate the activation of dendritic cells (DCs) and macrophages and promote the presentation of tumor antigens. Meanwhile, CHM can also reverse tumor-immune escape by enhancing T-cell proliferation and infiltration. In addition, CHM can also enhance the antitumor ability of the body by regulating the killing process of tumor cells. Conclusions: The theory of a CIC is of guiding significance to regulating tumor immunity via CHM.

Cannabis and Its Permissibility Status.

Cannabis has been used and misused to treat many disorders. Δ9-Tetrahydrocannabinol (THC) and cannabidiol (CBD) are the most important components of cannabis and could be used for recreational and medical purposes. The permissibility (Halal) status of cannabis is controversial, and its rational use is ambiguous. Global awareness and interest in cannabis use are increasing and its permissibility status, especially for recreational and medical purposes, needs to be addressed. Rationalizing the scientific value and Halal status of cannabis is useful for the rational use and maintenance of the compatible system. It is rare in Muslim countries to discuss the permissibility status of cannabis from the perspective of its value and composition. Using the analogy concept, the CBD component extracted from a cannabis plant in a clean and pure form is permissible to use in industry, particularly in cosmetics and pharmaceuticals. If THC component is present in <1% and CBD is >99%, the mixture is considered permissible as long as THC is not intentionally added or intentionally left, but is mainly present due to the limited capabilities and efficiency of the purification methods. However, any amount of THC prepared with the intention to be used as an intoxicant is considered non-Halal.

Halalopathy: A science of trust in medicine.

The human body is well organized, regulated and connected. One of the greatest scientific challenges today is to integrate mind, behaviour and health. Enormous advances in health care have been achieved. However, diseases like cancer still require treatment options beyond therapeutic drugs, namely surgery and radiation. Human being is not only made of cells, tissues and organs, but also feelings and sensations. Linking mental state with physical health is essential to include all elements of disease. For this purpose, halalopathy has been introduced as a new model to integrate mind, behaviour and health, where psychology, spirituality and rationality can be integrated together to generate a well-organized, regulated and connected health system. Halalopathic approaches are based on mind-trust-drug and mind-trust-belief. If the drug and human's belief are compatible, trust in the rationally designed drug will be synergized and placebo effects will be activated to initiate the healing process. Such an organized health system will lower the body's entropy and increase potential energy, which is an important aspect to promote the healing process, with a therapeutic drug toward complete recovery. This study enlightens laws of compatibility to initiate a domino chain effect to activate placebo effects and lower the body's entropy. The healing power of each effect will contribute to the healing process and enhance the total drug effects.

Superresolution imaging of individual replication forks reveals unexpected prodrug resistance mechanism.

Many drugs require extensive metabolism en route to their targets. High-resolution visualization of prodrug metabolism should therefore utilize analogs containing a small modification that does not interfere with its metabolism or mode of action. In addition to serving as mechanistic probes, such analogs provide candidates for theranostics when applied in both therapeutic and diagnostic modalities. Here a traceable mimic of the widely used anticancer prodrug cytarabine (ara-C) was generated by converting a single hydroxyl group to azide, giving "AzC." This compound exhibited the same biological profile as ara-C in cell cultures and zebrafish larvae. Using azide-alkyne "click" reactions, we uncovered an apparent contradiction: drug-resistant cells incorporated relatively large quantities of AzC into their genomes and entered S-phase arrest, whereas drug-sensitive cells incorporated only small quantities of AzC. Fluorescence microscopy was used to elucidate structural features associated with drug resistance by characterizing the architectures of stalled DNA replication foci containing AzC, EdU, γH2AX, and proliferating cell nuclear antigen (PCNA). Three-color superresolution imaging revealed replication foci containing one, two, or three partially resolved replication forks. Upon removing AzC from the media, resumption of DNA synthesis and completion of the cell cycle occurred before complete removal of AzC from genomes in vitro and in vivo. These results revealed an important mechanism for the low toxicity of ara-C toward normal tissues and drug-resistant cancer cells, where its efficient incorporation into DNA gives rise to highly stable, stalled replication forks that limit further incorporation of the drug, yet allow for the resumption of DNA synthesis and cellular division following treatment.

Chemoselective Modification of Vinyl DNA by Triazolinediones.

A new method for the post-synthetic modification of nucleic acids was developed that involves mixing a phenyl triazolinedione (PTAD) derivative with DNA containing a vinyl nucleobase. The resulting reactions proceeded through step-wise mechanisms, giving either a formal [4+2] cycloaddition product, or, depending on the context of nucleobase, PTAD addition along with solvent trapping to give a secondary alcohol in water. Catalyst-free addition between PTAD and the terminal alkene of 5-vinyl-2'-deoxyuridine (VdU) was exceptionally fast, with a second-order rate constant of 2×103 m-1 s-1 . PTAD derivatives selectively reacted with VdU-containing oligonucleotides in a conformation-selective manner, with higher yields observed for G-quadruplex versus duplex DNA. These results demonstrate a new strategy for copper-free bioconjugation of DNA that can potentially be used to probe nucleic acid conformations in cells.

Photodynamic agents with anti-metastatic activities.

A new concept in multifunctional anticancer agents is demonstrated. Tetrakis-(diisopropyl-guanidino) zinc phthalocyanine (Zn-DIGP) exhibits excellent properties as a photodynamic therapy (PDT) agent, as well as potential anti-metastatic activities in vivo. Zn-DIGP exhibits good cellular uptake and low toxicity in the dark (EC50 > 80 µM) and is well tolerated upon its intravenous injection into mice at 8 mg/kg. Upon photoexcitation with red laser light (660 nm), Zn-DIGP exhibits a high quantum yield for singlet oxygen formation (Φ ≈ 0.51) that results in potent phototoxicity to cell cultures (EC50 ≈ 0.16 µM). Zn-DIGP is also capable of inhibiting the formation of tumor colonies in the lungs of C57BL/6 mice injected with B16F10 cells. Zn-DIGP therefore inhibits cancer growth by both light-dependent and light-independent pathways. The anti-metastatic activities of Zn-DIGP possibly result from its ability to interfere with the signaling between chemokine CXCL10 and the G protein-coupled receptor CXCR3. Zn-DIGP is a competitive inhibitor of CXCR3 activation (IC50 = 3.8 µM) and selectively inhibits downstream events such as CXCL10-activated cell migration. Consistent with the presence of feedback regulation between CXCR3 binding and CXCL10 expression, Zn-DIGP causes overexpression of CXCL10. Interestingly, Zn-DIGP binds to CXCR3 without activating the receptor yet is able to cause endocytosis and degradation of this GPCR. To the best of our knowledge, Zn-DIGP is the first PDT agent that can facilitate the photodynamic treatment of primary tumors while simultaneously inhibiting the formation of metastatic tumor colonies by a light-independent mode of action.

Fluorescent probes for G-quadruplex structures.

Mounting evidence supports the presence of biologically relevant G-quadruplexes in single-cell organisms, but the existence of endogenous G-quadruplex structures in mammalian cells remains highly controversial. This is due, in part, to the common misconception that DNA and RNA molecules are passive information carriers with relatively little structural or functional complexity. For those working in the field, however, the lack of available tools for characterizing DNA structures in vivo remains a major limitation to addressing fundamental questions about structure-function relationships of nucleic acids. In this review, we present progress towards the direct detection of G-quadruplex structures by using small molecules and modified oligonucleotides as fluorescent probes. While most development has focused on cell-permeable probes that selectively bind to G-quadruplex structures with high affinity, these same probes can induce G-quadruplex folding, thereby making the native conformation of the DNA or RNA molecule (i.e., in the absence of probe) uncertain. For this reason, modified oligonucleotides and fluorescent base analogues that serve as "internal" fluorescent probes are presented as an orthogonal means for detecting conformational changes, without necessarily perturbing the equilibria between G-quadruplex, single-stranded, and duplex DNA. The major challenges and motivation for the development of fluorescent probes for G-quadruplex structures are presented, along with a summary of the key photophysical, biophysical, and biological properties of reported examples.

Synthesis of DNA interstrand cross-links using a photocaged nucleobase.

The missing linking: BCNU is a chemotherapy drug that generates an ethylene bridge between N(1) of deoxyguanosine and N(3) of deoxycytidine. No synthesis of a DNA containing this moiety has been reported until now. A new strategy uses a photocaged nucleobase that, when released, generates a highly reactive intermediate which cross-links the opposing DNA strand in a manner analogous to BCNU.

pH-mediated fluorescence and G-quadruplex binding of amido phthalocyanines.

A new family of G-quadruplex ligands termed "amido phthalocyanines" (APcs) was synthesized by reacting variable amino acids with tetraamino zinc phthalocyanine. Variation in the number of methylene units separating the APc scaffold from terminal ammonium groups systematically modulated ammonium pK(a) values that, in turn, mediated APc aggregation and DNA binding. Certain APcs exhibited nearly 1000-fold enhancements in fluorescence quantum yield upon binding G-quadruplex DNA under physiological conditions of pH and ionic strength. G-quadruplexes derived from the c-myc and c-kit promoters and the human telomeric repeat were evaluated for APc affinity and specificity using two complementary and direct fluorescence binding assays that revealed apparent dissociation constants ranging from 20 to 200 nM. Approximately 500-fold lower affinities for duplex and single-stranded DNAs were observed. Interestingly, APc-quadruplex binding was relatively insensitive to ionic strength (0.03-1 M KCl) but highly dependent on the pH of the solution. Our results provide a mechanism for the "turn-on" fluorescence properties exhibited by these compounds that will assist in future rational design of new G-quadruplex-specific fluorescent probes and drug candidates.

Cellular uptake and binding of guanidine-modified phthalocyanines to KRAS/HRAS G-quadruplexes.

Guanidino-modified phthalocyanines are evaluated in vitro (polymerase-stop assays and FRET) and in cultured cells as G4-DNA ligands and modulators of gene transcription.

An efficient two-step synthesis of metal-free phthalocyanines using a Zn(ii) template.

A new family of cationic phthalocyanines containing four guanidinium groups was synthesized in pyridine-HCl at 120 degrees C; under these conditions zinc was removed from both the starting materials and products to reveal a new synthetic route to metal-free phthalocyanines.

A modified thymine for the synthesis of site-specific thymine-guanine DNA interstrand crosslinks.

DNA interstrand crosslinks (ICLs) are highly cytotoxic lesions formed by a variety of important anti-tumor agents. Despite the clinical importance of ICLs, the mechanisms by which these lesions are repaired in mammalian cells have so far remained elusive. One of the obstacles in the study of ICL repair has been the limited availability of suitable methods for the synthesis of defined site-specific ICLs. We report here the synthesis of a site-specific ICL containing an ethylene-bridged G-T base pair based on the incorporation of a crosslink precursor containing a selectively reactive group on one strand using solid-phase synthesis. 3-(2-chloroethyl)thymidine was incorporated into oligonucleotides and underwent ICL formation upon annealing to a complementary strand by reacting with the base opposite to the modified T residue. A strong preference for ICL formation with a G residue opposite the reactive T was observed. Detailed characterization of the reaction product revealed that the alkylation reaction occurred with the O-6 group of G and a mechanism accounting for this preference is proposed. These G-T crosslinks introduced here will be useful for studies of ICL repair.

Site-specific incorporation of N-(deoxyguanosin-8-yl)-2-acetylaminofluorene (dG-AAF) into oligonucleotides using modified 'ultra-mild' DNA synthesis.

Aromatic amino and nitro compounds are potent carcinogens found in the environment that exert their toxic effects by reacting with DNA following metabolic activation. One important adduct is N-(deoxyguanosin-8-yl)-2-acetylaminofluorene (dG-AAF), which has been extensively used in studies of the mechanisms of DNA repair and mutagenesis. Despite the importance of dG-AAF adducts in DNA, an efficient method for its incorporation into DNA using solid-phase synthesis is still missing. We report the development of a modified 'ultra-mild' DNA synthesis protocol that allows the incorporation of dG-AAF into oligonucleotides of any length accessible by solid-phase DNA synthesis with high efficiency and independent of sequence context. Key to this endeavor was the development of improved deprotection conditions (10% diisopropylamine in methanol supplemented with 0.25 M of beta-mercaptoethanol) designed to remove protecting groups of commercially available 'ultra-mild' phosphoramidite building blocks without compromising the integrity of the exquisitely base-labile acetyl group at N8 of dG-AAF. We demonstrate the suitability of these oligonucleotides in the nucleotide excision repair reaction. Our synthetic approach should facilitate comprehensive studies of the mechanisms of repair and mutagenesis induced by dG-AAF adducts in DNA and should be of general use for the incorporation of base-labile functionalities into DNA.