Hybrids from Farnesylthiosalicylic Acid and Hydroxamic Acid as Dual Ras-Related Signaling and Histone Deacetylase (HDAC) Inhibitors: Design, Synthesis and Biological Evaluation

Novel one-/two-photon excited carbazole/quinolinium photosensitizers manifest nanomolar and hypoxia-resistant tumor photodynamic therapy by accelerating apoptosis, ferroptosis, and autophagy

Photodynamic therapy (PDT) holds potential in cancer treatment, but the development of photosensitizers with high-efficient PDT remains a challenge. Herein, we designed and synthesized a series of novel tricyclic carbazole/quinolinium hybrids-KNKQ, KAKQ, and KPKQ-as photosensitizers, and subsequently evaluated their photodynamic anticancer activities and the associated mechanisms. Among them, KPKQ exhibited the most prominent one-/two-photon activated photodynamic characteristics, generating •O2-, •OH, and 1O2. Particularly, the 1O2 quantum yield of KPKQ was 3∼9-fold stronger than KNKQ and KAKQ. Most interestingly, KPKQ demonstrated nanomolar-level and hypoxic-overcoming single-photon phototoxicities with IC50 values of 27∼43 nM (PIs = 46-54), significantly surpassing existing tricyclic carbazole photosensitizers, and also exerted potent photodynamic therapeutic effects (IC50s = 0.13-0.20 μM) via two-photon excitation at 808 nm. Furthermore, KPKQ significantly promoted mitochondrial damage, cell apoptosis, and DNA lesion via reducing Bcl-2 level and increasing the levels of Bax, cleaved-Caspase-3, and γ-H2AX. Concurrently, KPKQ lowered GSH/GPX4 levels and elevated malondialdehyde to trigger ferroptosis. Additionally, KPKQ powerfully promoted autophagy through boosting LC3-II and Beclin-1 expression, thereby demonstrating a multiple anti-tumor mechanism. Ultimately, KPKQ achieved a 90.7 % tumor-inhibitory rate through in vivo PDT. Our findings may provide a promising framework for the discovery of novel tricyclic carbazole photosensitizers with high PDT efficacy.

Structural insights, regulation, and recent advances of RAS inhibitors in the MAPK signaling cascade: a medicinal chemistry perspective

The MAPK pathway has four main components: RAS, RAF, MEK, and ERK. Among these, RAS is the most frequently mutated protein and the leading cause of cancer. The three isoforms of the RAS gene are HRAS, NRAS, and KRAS. The KRAS gene is characterized by two splice variants, K-Ras4A and K-Ras4B. The occurrence of cancer often involves a mutation in both KRAS4A and KRAS4B. In this study, we have elucidated the mechanism of the RAS protein complex and the movement of switches I and II. Only two RAS inhibitors, sotorasib and adagrasib, have been approved by the FDA, and several are in clinical trials. This review comprises recent developments in synthetic RAS inhibitors, their unique properties, their importance in inhibiting RAS mutations, and the current challenges in developing new RAS inhibitors. This review will undoubtedly help researchers design novel RAS inhibitors.

Discovery of Novel Src Homology-2 Domain-Containing Phosphatase 2 and Histone Deacetylase Dual Inhibitors with Potent Antitumor Efficacy and Enhanced Antitumor Immunity

Both Src homology-2 domain-containing phosphatase 2 (SHP2) and histone deacetylase (HDAC) are important oncoproteins and potential immunomodulators. In this study, we first observed a synergistic antiproliferation effect of an allosteric SHP2 inhibitor (SHP099) and HDAC inhibitor (SAHA) in MV4-11 cells. Inspired by this result, a series of SHP2/HDAC dual inhibitors were designed based on the pharmacophore fusion strategy. Among these inhibitors, the most potent compound 8t showed excellent inhibitory activities against SHP2 (IC₅₀ = 20.4 nM) and HDAC1 (IC₅₀ = 25.3 nM). In particular, compound 8t exhibited improved antitumor activities compared with those of SHP099 and SAHA in vitro and in vivo. Our study also indicated that treatment with 8t could trigger efficient antitumor immunity by activating T cells, enhancing the antigen presentation function and promoting cytokine secretion. To our knowledge, we report the first small molecular SHP2/HDAC dual inhibitor and demonstrate a new strategy for cancer immunotherapy.

Combining histone deacetylase inhibitors (HDACis) with other therapies for cancer therapy

Histone deacetylases (HDACs) play an important role in regulating the expression of genes involved in tumorigenesis and tumor maintenance, and hence they have been considered as key targets in cancer therapy. As a novel category of antitumor agents, histone deacetylase inhibitors (HDACis) can induce cell cycle arrest, apoptosis, and differentiation in cancer cells, ultimately combating cancer. Although in the United States, the use of HDACis for the treatment of certain cancers has been approved, the therapeutic efficacy of HDACis as a single therapeutic agent in solid tumorshas been unsatisfactory and drug resistance may yet occur. To enhance therapeutic efficacy and limit drug resistance, numerous combination therapies involving HDACis in synergy with other antitumor therapies have been studied. In this review, we describe the classification of HDACs. Moreover, we summarize the antitumor mechanism of the HDACis for targeting key cellular processes of cancers (cell cycle, apoptosis, angiogenesis, DNA repair, and immune response). In addition, we outline the major developments of other antitumor therapies in combination with HDACis, including chemotherapy, radiotherapy, phototherapy, targeted therapy, and immunotherapy. Finally, we discuss the current state and challenges of HDACis-drugs combinations in future clinical studies, with the aim of optimizing the antitumor effect of such combinations.

Contribution of opioid and neurotensin receptors in the anti-inflammatory activity of PK20 hybrid compound in murine airways

PK20 is an anti-inflammatory hybrid compound, composed of an endomorphin-2-like and neurotensin-like fragments. The aim of the present study is to assess the contribution of particular pharmacophores to the activity of the hybrid tested. For this purpose, airway hyperresponsiveness, accumulation of inflammatory cells in bronchoalveolar lavage fluid (BALF), concentration of mouse mast cell protease, malondialdehyde and secretory phospholipase 2 activity in lung tissue, as well as production of pro-inflammatory cytokines in BALF and lung were determined by using murine model of non-atopic asthma. Blocking either neurotensin receptors or mu opioid receptors did not alter the potential of PK20 in reducing airway hyperresponsiveness. In studies of inflammatory cells, the beneficial effect of the entire peptide occurs to be mediated by the stimulation of neurotensin receptors. However, regarding cytokine and biochemical assays, pretreatment with both receptor antagonists resulted in a different effect on its activity depending on the parameter studied. To conclude, the activation of both the opioid and neurotensin receptors seems to be necessary to induce the full anti-inflammatory activity of the hybrid compound.

Synthesis and evaluation of diphyllin β-hydroxyl amino derivatives as novel V-ATPase inhibitors

Natural diphyllin glycosides were identified as potent vacuolar H⁺ -ATPase (V-ATPase) inhibitors. A series of diphyllin β-hydroxyl amino derivatives were designed and synthesized as novel diphyllin derivatives. Most of these derivatives displayed potent cytotoxicity against six cancer cell lines with IC₅₀ values in the submicromolar to nanomolar concentration range. Compounds 2b, 2c, 2l, 2m, and 2n showed similar V-ATPase inhibitory potency to Bafilomycin A1. Compound 2l exhibited potent activity of modulation of lysosomal pH and cytoplasmic pH.

Recent Advances in Multi-target Drugs Targeting Protein Kinases and Histone Deacetylases in Cancer Therapy

Protein Kinase Inhibitors (PKIs) and Histone Deacetylase Inhibitors (HDACIs) are two important classes of anticancer agents and have provided a variety of small molecule drugs for the treatment of various types of human cancers. However, malignant tumors are of a multifactorial nature that can hardly be "cured" by targeting a single target, and treatment of cancers hence requires modulation of multiple biological targets to restore the physiological balance and generate sufficient therapeutic efficacy. Multi-target drugs have attracted great interest because of their advantages in the treatment of complex cancers by simultaneously targeting multiple signaling pathways and possibly leading to synergistic effects. Synergistic effects have been observed in the combination of kinase inhibitors, such as imatinib, dasatinib, or sorafenib, with an array of HDACIs including vorinostat, romidepsin, or panobinostat. A considerable number of multi-target agents based on PKIs and HDACIs have been developed. In this review, we summarize the recent literature on the development of multi-target kinase-HDAC inhibitors and provide our view on the challenges and future directions on this topic.

Synthesis, Cytotoxicity, Anti-migration and Anti-invasion Activity of Diphyllin Heterocyclic Derivatives

BACKGROUND

Diphyllin, an arylnaphthalene lignan lactone, isolated from many traditional medicinal plants, has been reported to possess anticancer and antiviral activities. Natural diphyllin and its glycosides were identified as potent vacuolar H+ -ATPase (V-ATPase) inhibitors.

OBJECTIVE

The aim of this study was to design and synthesize a series of heterocyclic derivatives of diphyllin as novel anticancer agents.

METHODS

The targeted heterocyclic derivatives of diphyllin were synthesized from diphyllin employing etherification reaction and N-substitution reaction. Cytotoxicity of these compounds on four cancer cells was assessed by MTT assay. The inhibitory activity of V-ATPase of compound 3n was measured on MGC-803 cells. Anti-migration and anti-invasion abilities were assessed by transwell invasion assay and scratch wound assay.

RESULTS

Most of these derivatives displayed potent cytotoxicity on four cancer cells at submicromolar concentrations. The most potent derivative 3n has been shown to inhibited V-ATPase activity, migration and invasion abilities on MGC-803 cells at 0.75 mM.

CONCLUSION

The collective results clearly indicate that heterocyclic derivatives of diphyllin inhibit the viability, V-ATPase activity, migration and invasion of the MGC803 cells. The current findings provide valuable insights for the future development of novel diphyllin derivatives as anticancer agents.

Comprehensive review for anticancer hybridized multitargeting HDAC inhibitors

Despite the encouraging clinical progress of chemotherapeutic agents in cancer treatment, innovation and development of new effective anticancer candidates still represents a challenging endeavor. With 15 million death every year in 2030 according to the estimates, cancer has increased rising of an alarm as a real crisis for public health and health systems worldwide. Therefore, scientist began to introduce innovative solutions to control the cancer global health problem. One of the promising strategies in this issue is the multitarget or smart hybrids having two or more pharmacophores targeting cancer. These rationalized hybrid molecules have gained great interests in cancer treatment as they are capable to simultaneously inhibit more than cancer pathway or target without drug-drug interactions and with less side effects. A prime important example of these hybrids, the HDAC hybrid inhibitors or referred as multitargeting HDAC inhibitors. The ability of HDAC inhibitors to synergistically improve the efficacy of other anti-cancer drugs and moreover, the ease of HDAC inhibitors cap group modification prompt many medicinal chemists to innovate and develop new generation of HDAC hybrid inhibitors. Notably, and during this short period, there are four HDAC inhibitor hybrids have entered different phases of clinical trials for treatment of different types of blood and solid tumors, namely; CUDC-101, CUDC-907, Tinostamustine, and Domatinostat. This review shed light on the most recent hybrids of HDACIs with one or more other cancer target pharmacophore. The designed multitarget hybrids include topoisomerase inhibitors, kinase inhibitors, nitric oxide releasers, antiandrogens, FLT3 and JAC-2 inhibitors, PDE5-inhibitors, NAMPT-inhibitors, Protease inhibitors, BRD4-inhibitors and other targets. This review may help researchers in development and discovery of new horizons in cancer treatment.

Paradigm shift of "classical" HDAC inhibitors to "hybrid" HDAC inhibitors in therapeutic interventions

'Epigenetic' regulation of genes via post-translational modulation of proteins is the current mainstay approach for the disease therapies, particularly explored in the Histone Deacetylase (HDAC) class of enzymes. Mainly sight saw in cancer chemotherapeutics, HDAC inhibitors have also found a promising role in other diseases (neurodegenerative disorders, cardiovascular diseases, and viral infections) and successfully entered in various combination therapies (pre-clinical/clinical stages). The prevalent flexibility in the structural design of HDAC inhibitors makes them easily tuneable to merge with other pharmacophore modules for generating multi-targeted single hybrids as a novel tactic to overcome drawbacks of polypharmacy. Herein, we reviewed the putative role of prevalent HDAC hybrids inhibitors in the current and prospective stage as a translational approach to overcome the limitations of the existing conventional drug candidates (parent molecule) when used either alone (drug resistance, solubility issues, adverse side effects, selectivity profile) or in combination (pharmacokinetic interactions, patient compliance) for treating various diseases.

Bimetallic Catalyzed N-arylation Used in Synthesis of Novel β-carbolines Derivatives

Background:

Natural occurring β-Carbolines alkaloids are abundant in the plant kingdom or other organisms, and they were found to possess good antitumor activity through multiple mechanisms. Based on previous summarized SARs of β-carboline derivatives, the modification on pyridine ring would have a great impact on their antitumor activities. Therefore, we plan to synthesized arylated β-carboline-3-amides to find more valuable β-Carbolines derivatives.

Methods:

A novel bimetallic Pd(OAc)2/AgOAc catalyst system was developed for the amidation of aryl iodides under acid condition. A series of N-arylated β-carbolines derivatives were synthesized using this method. The structures of these compounds were confirmed by 1H NMR, 13C NMR and HRMS, and their in vitro antiproliferative activity was investigated against HepG2 and Hela tumor cell lines by MTT assay.

Results:

Eleven N-arylated β-carboline-3-amides were synthesized using this bimetallic catalyzed method in 58-98% yields. These synthesized N-arylated compounds showed no antiproliferative activity at 20 μM.

Conclusion:

We have discovered an efficient and bimetallic catalytic system allowing the Narylation of secondary acyclic amides. This is the first report that N-arylation of aliphatic secondary acyclic amides under acid condition.

Dual-Target Inhibitors Based on HDACs: Novel Antitumor Agents for Cancer Therapy

Histone deacetylases (HDACs) play an important role in regulating target gene expression. They have been highlighted as a novel category of anticancer targets, and their inhibition can induce apoptosis, differentiation, and growth arrest in cancer cells. In view of the fact that HDAC inhibitors and other antitumor agents, such as BET inhibitors, topoisomerase inhibitors, and RTK pathway inhibitors, exert a synergistic effect on cellular processes in cancer cells, the combined inhibition of two targets is regarded as a rational strategy to improve the effectiveness of these single-target drugs for cancer treatment. In this review, we discuss the theoretical basis for designing HDAC-involved dual-target drugs and provide insight into the structure-activity relationships of these dual-target agents.

Antitumor, Antiviral, and Anti-Inflammatory Efficacy of Essential Oils from Atractylodes macrocephala Koidz. Produced with Different Processing Methods

Atractylodes macrocephala Koidz. has been used as an invigorating spleen drug for eliminating dampness and phlegm in China. According to recent researches, different processing methods may affect the drug efficacy, so we collected A. macrocephala from the Zhejiang Province, produced with different processing methods, crude A. macrocephala (CA) and bran-processed A. macrocephala (BA), then analyzed its essential oils (EOs) by GC/MS. The results showed 34 components representing 98.44% of the total EOs of CA were identified, and 46 components representing 98.02% of the total EOs of BA were identified. Atractylone is the main component in A. macrocephala. Compared with CA, BA has 46 detected compounds, 28 of which were identical, and 6 undetected compounds. Pharmacodynamic results revealed that the EOs of CA and atractylone exhibited more effective anticancer activity in HepG2, MCG803, and HCT-116 cells than the EOs of BA; while the EOs of BA exhibited simple antiviral effect on viruses H3N2, both the EOs and atractylone show anti-inflammatory activity by inhibiting the lipopolysaccharide (LPS)-induced nitric oxide (NO) production in ANA-1 cells.

Synthesis and Antichlamydial Activity of Novel Phenazines

Results:

C-4 morpholinyl 8a and C-4 phenyl phenazine 9c exhibited stronger antichlamydial activity with no apparent cytotoxicity. Both phenazine derivatives inhibited chlamydial inclusions formation and growth in a dose-dependent manner. They inhibited Chlamydia infection by reducing elementary body infectivity and disturbing Chlamydia growth at the mid-stage of the chlamydial developmental cycle.

Conclusion:

Our findings suggest C-4 aryl and C-4 amino phenazine derivatives as promising lead molecules for antichlamydials development.

Epigenetic polypharmacology: from combination therapy to multitargeted drugs

The modern drug discovery process has largely focused its attention in the so-called magic bullets, single chemical entities that exhibit high selectivity and potency for a particular target. This approach was based on the assumption that the deregulation of a protein was causally linked to a disease state, and the pharmacological intervention through inhibition of the deregulated target was able to restore normal cell function. However, the use of cocktails or multicomponent drugs to address several targets simultaneously is also popular to treat multifactorial diseases such as cancer and neurological disorders. We review the state of the art with such combinations that have an epigenetic target as one of their mechanisms of action. Epigenetic drug discovery is a rapidly advancing field, and drugs targeting epigenetic enzymes are in the clinic for the treatment of hematological cancers. Approved and experimental epigenetic drugs are undergoing clinical trials in combination with other therapeutic agents via fused or linked pharmacophores in order to benefit from synergistic effects of polypharmacology. In addition, ligands are being discovered which, as single chemical entities, are able to modulate multiple epigenetic targets simultaneously (multitarget epigenetic drugs). These multiple ligands should in principle have a lower risk of drug-drug interactions and drug resistance compared to cocktails or multicomponent drugs. This new generation may rival the so-called magic bullets in the treatment of diseases that arise as a consequence of the deregulation of multiple signaling pathways provided the challenge of optimization of the activities shown by the pharmacophores with the different targets is addressed.

Salinomycin Hydroxamic Acids: Synthesis, Structure, and Biological Activity of Polyether Ionophore Hybrids

The polyether ionophore salinomycin has recently gained attention due to its exceptional ability to selectively reduce the proportion of cancer stem cells within a number of cancer cell lines. Efficient single step strategies for the preparation of hydroxamic acid hybrids of this compound varying in N- and O-alkylation are presented. The parent hydroxamic acid, salinomycin-NHOH, forms both inclusion complexes and well-defined electroneutral complexes with potassium and sodium cations via 1,3-coordination by the hydroxamic acid moiety to the metal ion. A crystal structure of an cationic sodium complex with a noncoordinating anion corroborates this finding and, moreover, reveals a novel type of hydrogen bond network that stabilizes the head-to-tail conformation that encapsulates the cation analogously to the native structure. The hydroxamic acid derivatives display down to single digit micromolar activity against cancer cells but unlike salinomycin selective reduction of ALDH(+) cells, a phenotype associated with cancer stem cells was not observed. Mechanistic implications are discussed.

Multitarget Drugs: an Epigenetic Epiphany

Epigenetics refers to changes in a biological phenotype that are not due to an underlying change in genotype. In eukaryotes, epigenetics involves a set of chemical modifications of the DNA and the histone proteins in nucleosomes. These dynamic changes are carried out by enzymes and modulate protein-protein and protein-nucleic acid interactions to determine whether specific genes are expressed or silenced. Both the epigenetic enzymes and recognition domains are currently important drug discovery targets, particularly for the treatment of cancer. This review summarizes the progress of epigenetic targets that have reached a clinical stage: DNA methyltransferases, histone deacetylases, lysine methyltransferases, lysine demethylases, and bromodomains; this is followed by a comprehensive survey of multitarget drugs that have included an epigenetic target as one of their mechanisms of action.