The Role of Indirubins in Inflammation and Associated Tumorigenesis

Indirubin alleviates retinal neurodegeneration through the regulation of PI3K/AKT signaling

Retinal neurodegenerative disease is a leading cause of blindness among the elderly in developed countries, including glaucoma, diabetic retinopathy, traumatic optic neuropathy and optic neuritis, etc. The current clinical treatment is not very effective. We investigated indirubin, one of the main bioactive components of the traditional Chinese medicine Danggui Longhui Pill, in the present study for its role in retinal neurodegeneration. Indirubin exhibited no detectable tissue toxicity in vivo or cytotoxicity in vitro. Moreover, indirubin improved visual function and ameliorated retinal neurodegeneration in mice after optic nerve crush injury in vivo. Furthermore, indirubin reduced the apoptosis of retinal ganglion cells induced by oxidative stress in vitro. In addition, indirubin significantly suppressed the increased production of intracellular reactive oxygen species and the decreased activity of superoxide dismutase induced by oxidative stress. Mechanically, indirubin played a neuroprotective role by regulating the PI3K/AKT/BAD/BCL-2 signaling. In conclusion, indirubin protected retinal ganglion cells from oxidative damage and alleviated retinal neurodegeneration induced by optic nerve crush injury. The present study provides a potential therapeutic medicine for retinal neurodegenerative diseases.

Pinpointing top inhibitors for GSK3β from pool of indirubin derivatives using rigorous computational workflow and their validation using molecular dynamics (MD) simulations

Glycogen synthase kinase-3β (GSK3β) is a pivotal protein kinase implicated in a spectrum of debilitating diseases, encompassing cancer, diabetes, and neurodegenerative disorders. While the therapeutic potential of GSK3β inhibition is widely recognized, there remains an unmet need for a rigorous, systematic analysis probing the theoretical inhibition dynamics of a comprehensive library of indirubin derivatives against GSK3β using advanced computational methodologies. Addressing this gap, this study embarked on an ambitious endeavor, leveraging indirubin-a renowned scaffold-as a template to curate a vast library of 1000 indirubin derivatives from PubChem. These were enriched with varied substitutions and modifications, identified via a structure similarity search with a Tanimoto similarity threshold of 85%. Harnessing a robust virtual screening workflow, we meticulously identified the top 10 contenders based on XP docking scores. Delving deeper, we gauged the binding free energy differentials (ΔGBind) of these hits, spotlighting the top three compounds that showcased unparalleled binding prowess. A comparative pharmacophore feature mapping with the reference inhibitor OH8, co-crystallized with GSK3β (PDB ID: 6Y9R), was undertaken. The binding dynamics of these elite compounds were further corroborated with 100 ns molecular dynamics simulations, underlining their stable and potent interactions with GSK3β. Remarkably, our findings unveil that these indirubin derivatives not only match but, in certain scenarios, surpass the binding affinity and specificity of OH8. By bridging this research chasm, our study amplifies the therapeutic promise of indirubin derivatives, positioning them as frontrunners in the quest for groundbreaking GSK3β inhibitors, potentially revolutionizing treatments for a myriad of ailments.

Network pharmacology and in vivo and in vitro experiments to determine the mechanism behind the effects of Jiawei Yanghe decoction via TLR4/Myd88/NF-κB against mastitis

Background

In the Qing dynasty, Yanghe decoction was as a therapeutic soup for effectively treating chronic inflammatory disorders. It was used as a therapeutic soup for effectively treating chronic inflammatory disorders. In the clinical use of Yanghe decoction, the adjustment of the medication for a variety of inflammatory diseases have therapeutic effect, including mastitis. Therefore, Jiawei Yanghe decoction (JWYHD) may be used to treat inflammatory breast diseases.

Methods

First, LM- and JWYHD-related components were retrieved from the database and analysis platform. Next, protein-protein interaction networks were constructed to screen the key targets, and gene ontology and Kyoto encyclopedia of gene and genome enrichment analyses were performed to predict the potential biological functions and mechanisms of JWYHD. Simultaneously, the JWYHD samples were collected and analyzed by UPLC-HRMS. Finally, in vivo and in vitro experiments were conducted to construct animal and cellular inflammation models of mastitis with LPS. Pathological changes in the mammary tissues were detected. Enzyme-linked immunosorbent assay, reverse transcription-polymerase chain reaction, and Western blotting was performed to determine the mRNA and protein levels of inflammatory cytokines and toll-like receptor 4/myeloid differentiation primary response 88/nuclear factor kappa B signaling pathway in the breast tissues to elucidate the potential underlying mechanisms of anti-mastitis effects of JWYHD from different aspects.

Results

In total, 103 compounds were detected in JWYHD by UPLC-HRMS. 691 active ingredients of JWYHD were screened by network pharmacology, and 47 LM-related targets were identified. The PPI network analysis of the targets revealed the 5 core targets. The KEGG enrichment results established the NF-κB signaling pathways as the core. After JWYHD intervention, low inflammatory enrichment and mild inflammatory damage in breast tissues were observed. Furthermore, JWYHD treatment affected mammary gland inflammatory cytokines and the TLR4/Myd88/NF-κB signaling pathway by considerably reducing the respective protein levels and gene expression; thus, JWYHD alleviated LM symptoms.

Conclusions

We hypothesized and demonstrated the anti-inflammatory effects of JWYHD by cytokine regulation via the TLR4/Myd88/NF-κB signaling pathway. In conclusion, JWYHD showed its potential in LM treatment and in treating other acute and chronic inflammatory diseases.

Synthesis and antibacterial activity studies in vitro of indirubin-3'-monoximes

Multi-drug-resistant microbial pathogens are a serious global health problem. New compounds with antibacterial activity serve as good candidates for developing novel antibacterial drugs which is very urgent and important. In this work, based on the unique scaffold of indirubin, an active ingredient of traditional Chinese medicine formulation Danggui Luhui Wan, we synthesized 29 indirubin-3'-monoximes and preliminarily evaluated their antibacterial activities. The antibacterial activity results demonstrated that the synthesized indirubin-3'-monoximes 5a-5z and 5aa-5ad displayed good potency against S. aureus ATCC25923 (MIC = 0.4-25.6 μg mL-1). Among them, we found that the 5-F, 5-Cl and 7-CF3 substituted indirubin-3'-monoximes 5r, 5s and 5aa also showed better antibacterial efficiency for S. aureus (MICs up to 0.4 μg mL-1) than the prototype natural product indirubin (MIC = 32 μg mL-1). More importantly, indirubin-3'-monoxime 5aa has certain synergistic effect with levofloxacin against clinic multidrug-resistant S. aureus (fractional inhibitory concentration index: 0.375). In addition, relevant experiments including electron microscopy observations, PI staining and the leakage of extracellular potassium ions and nucleic acid (260 nm) have been performed after treating S. aureus with indirubin-3'-monoxime 5aa, and the results revealed that indirubin-3'-monoximes could increase the cell membrane permeability of S. aureus. Although indirubin-3'-monoxime 5aa showed some cytotoxicity toward SH-SY5Y cells relative to compounds 5r and 5s, the skin irritation test of male mice after shaving showed that compound 5aa at a concentration of 12.8 μg mL-1 had no toxicity to mouse skin, and it could be used as a leading compound for skin antibacterial drugs.

Mechanism of Anti-Inflammatory and Antibacterial Effects of QingXiaoWuWei Decoction Based on Network Pharmacology, Molecular Docking and In Vitro Experiments

Background and Aim: QingXiaoWuWei Decoction (QXWWD) is a traditional Chinese medicine that is commonly used in clinical settings to treat inflammatory and bacterial diseases. However, there is still a lot to learn about its molecular mechanism. A network pharmacology approach was applied to investigate the pharmacological mechanisms of QXWWD in inflammation treatment.

Methods: The basic mechanisms involved in the anti-inflammatory and antibacterial potentials of QXWWD were identified using network pharmacology and molecular docking. The principal components of QXWWD were identified by the HPLC-Q-Exactive-MS method. The antibacterial bioactivity of QXWWD was further investigated using the Kirby-Bauer disc diffusion method and the determination of the minimum inhibitory concentration. The anti-inflammatory activity of QXWWD was evaluated using mice ear swelling test, RAW264.7 cell culture, and pro-inflammatory cytokines measurement. Skin irritation and HE staining were employed to evaluate the safety of QXWWD topical use and to depict the drug’s potential therapeutic function. The hub genes and signaling pathways associated with inflammatory and bacterial diseases were validated by western blot in addition to biochemical and pathological markers.

Results: Our findings revealed that the ethanolic extract of QXWWD had a strong inhibitory effect against Staphylococcus aureus, Enterococcus faecalis, and Streptococcus pneumoniae. Meanwhile, QXWWD was potentially effective in suppressing ear swelling, elevated white blood cell counts, and the TNF-α, IL-1, and IL-6 levels. According to skin irritation, QXWWD was found to be safe when tested for topical application. The results of HE staining showed that the possible therapeutic role of QXWWD was related to the change in skin microstructure. Also, the network pharmacology, molecular docking as well as Q-Exactive-MS and HPLC analysis suggested that the synergistic effect of quercetin, luteolin and other ingredients could serve as main contributor of QXWWD for its anti-inflammatory and antibacterial activities. Moreover, the JUN, MAPK1, RELA, NFKBIA, MYC, and AKT1 were the potential identified key targets, and MAPK/PI3K/Akt was among the possibly involved signaling pathways in the anti-inflammatory and antibacterial activities of QXWWD.

Conclusions: From a therapeutic standpoint, QXWWD may be a promising antibacterial and anti-inflammatory agent for the treatment of bacterial, acute, and chronic dermatitis.

Pulmonary Arterial Hypertension Secondary to Drugs and Toxins

Pulmonary arterial hypertension secondary to drugs and toxins is an important subgroup of group 1 pulmonary hypertension associated with significant morbidity and mortality. Many drugs and toxins have emerged as risk factors for pulmonary arterial hypertension, which include anorexigens, illicit agents, and several US Food and Drug Administration-approved therapeutic medications. Drugs and toxins are classified as possible or definite risk factors for pulmonary arterial hypertension. This article reviews agents that have been implicated in the development of pulmonary arterial hypertension, their pathologic mechanisms, and methods to prevent the next deadly outbreak of drug- and toxin-induced pulmonary arterial hypertension.

An update on the pathophysiology of immune thrombocytopenia

: Immune thrombocytopenia (ITP) is an autoimmune bleeding disorder mediated by antiplatelet autoantibodies and antigen-specific T cells that either destroy platelets peripherally in the spleen or impair platelet production in the bone marrow. There have been a plethora of publications relating to the pathophysiology of ITP and since January of 2019, at least 50 papers have been published on ITP pathophysiology.

PURPOSE OF REVIEW

To summarize the literature relating to the pathophysiology of ITP including the working mechanisms of therapies, T-cell and B-cell physiology, protein/RNA/DNA biochemistry, and animal models in an attempt to unify the perceived abnormal immune processes.

RECENT FINDINGS

The most recent pathophysiologic irregularities associated with ITP relate to abnormal T-cell responses, particularly, defective T regulatory cell activity and how therapeutics can restore these responses. The robust literature on T cells in ITP points to the notion that ITP is a disease initiated by faulty self-tolerance mechanisms very much like that of other organ-specific autoimmune diseases. There is also a large literature on new and existing animal models of ITP and these will be discussed. It appears that understanding how to specifically modulate T cells in patients with ITP will undoubtedly lead to effective antigen-specific therapeutics.

CONCLUSIONS

ITP is predominately a T cell disorder which leads to a breakdown in self tolerance mechanisms and allows for the generation of anti-platelet autoantibodies and T cells. Novel therapeutics that target T cells may be the most effective way to perhaps cure this disorder.

Indirubin attenuates IL-17A-induced CCL20 expression and production in keratinocytes through repressing TAK1 signaling pathway

Psoriatic skin inflammation is mainly driven by complex interactions of infiltrating immune cells and activated keratinocytes. Keratinocytes play an active role in initiating and maintenance of psoriatic skin inflammation by secreting chemokines and cytokines. IL-17A produced by T cells potently upregulates the production of chemokine CCL20 in the keratinocytes, which further chemoattracts IL-17A-producing CCR6+ immune cells to the site of inflammation. Indirubin, an active constituent of indigo naturalis, has been reported to possess anti-inflammatory activities, but whether it can suppress the production of chemokines in keratinocytes is largely unknown. To address this question, IL-17A stimulated HaCaT cells were used as cell model to explore the effects of indirubin on the expression and secretion of chemokines. Also, RNA-seq analysis was performed to extensively understand the entire gene expression changes after indirubin treatment and identify the differentially expressed genes further. Indirubin treatment strongly inhibited CCL20 expression and secretion in IL-17A stimulated HaCaT cells. The inhibitory action of indirubin on CCL20 expression was mainly mediated by TAK1 signaling pathway in a mouse psoriasis-like model and cultured HaCaT cells in vitro. Combining with our previous report, indirubin ameliorated psoriasiform dermatitis by breaking CCL20/CCR6 axis-mediated inflammatory loops. Our results provide novel insights into the mechanisms of indirubin in the treatment of psoriasis.

Indirubin-3'-monoxime induces paraptosis in MDA-MB-231 breast cancer cells by transmitting Ca2+ from endoplasmic reticulum to mitochondria

PURPOSE

Indirubin-3'-monoxime (I3M) induces cell death in many cancer cells; however, whether I3M regulates paraptosis is unclear. The present study aimed to investigate I3M-induced paraptosis.

METHODS

We treated various cancer cells with I3M, and measured vacuole formation (a paraptosis marker) and the regulating signaling pathway such as endoplasmic reticulum (ER) stress, reactive oxygen species, and proteasomal dysfunction.

RESULTS

We found that I3M induced small vacuole formation in MDA-MB-231 breast cancer cells and transient knockdown of eIF2α and CHOP significantly downregulated vacuolation in the ER and mitochondria, as well as cell death in response to I3M, indicating that I3M-meditaed paraptosis was upregulated by ER stress. Moreover, I3M accumulated ubiquitinylated proteins via proteasome dysfunction, which stimulated ER stress-mediated Ca²⁺ release. A Ca²⁺ chelator significantly downregulated vacuolation in the ER and mitochondria as well as cell death, suggesting that Ca²⁺ was a key regulator in I3M-induced paraptosis. Our results also revealed that Ca²⁺ finally transited in mitochondria through mitochondrial Ca²⁺ uniporter (MCU), causing I3M-mediated paraptosis; however, the paraptosis was completely inhibited by, ruthenium red, an MCU inhibitor.

CONCLUSION

I3M induced proteasomal dysfunction-mediated ER stress and subsequently promoted Ca²⁺ release, which was accumulated in the mitochondria via MCU, thus causing paraptosis in MDA-MB-231 breast cancer cells.

The indirubin derivative 6-bromoindirubin-3'-glycerol-oxime ether (6BIGOE) potently modulates inflammatory cytokine and prostaglandin release from human monocytes through GSK-3 interference

Indirubin is a natural bis-indole alkaloid contained as active ingredient in the traditional Chinese remedy Danggui Longhui Wan. Indirubin and its 3'-oxime derivatives exhibit anti-cancer and anti-inflammatory properties and they inhibit glycogen synthase kinase (GSK)-3 in cell-free assays where 6-bromoindirubin-3'-oxime (6BIO) is among the most potent analogs. Here, we reveal 6-bromoindirubin-3'-glycerol-oxime ether (6BIGOE) as highly potent derivative able to inhibit pro-inflammatory cytokine, chemokine and prostaglandin (PG) release in human primary monocytes while increasing anti-inflammatory interleukin (IL)-10 levels. 6BIGOE suppressed lipopolysaccharide (LPS)-induced IL-1β and PGE₂ release with IC₅₀ of 0.008 and 0.02 µM, respectively, being ≥ 12-fold more potent than 6BIO. The effects of 6BIGOE are mediated via intracellular inhibition of GSK-3, where 6BIGOE again surpassed the effectiveness of 6BIO despite the higher potency of the latter in cell-free GSK-3 activity assays. Side-by-side comparison of 6BIGOE (0.1 µM) with the selective GSK-3 inhibitor SB216763 (5 µM) revealed congruent properties such as enrichment of β-catenin and suppression of cyclooxygenase (COX)-2 protein levels due to GSK-3 inhibition. Metabololipidomics using ultra-performance liquid chromatography-tandem mass spectrometry showed that 6BIGOE selectively decreases pro-inflammatory COX-derived product formation without marked modulation of other lipid mediators. In summary, 6BIGOE is a highly potent indirubin derivative in the cellular context that favorably modulates pro- and anti-inflammatory cytokines as well as COX-2-derived PG via interference with GSK-3.

Targeting the JAK/STAT Signaling Pathway Using Phytocompounds for Cancer Prevention and Therapy

Cancer is a prevalent cause of mortality around the world. Aberrated activation of Janus kinase (JAK)/signal transducer and activator of transcription (STAT) signaling pathway promotes tumorigenesis. Natural agents, including phytochemicals, exhibit potent anticancer activities via various mechanisms. However, the therapeutic potency of phytoconstituents as inhibitors of JAK/STAT signaling against cancer has only come into focus in recent days. The current review highlights phytochemicals that can suppress the JAK/STAT pathway in order to impede cancer cell growth. Various databases, such as PubMed, ScienceDirect, Web of Science, SpringerLink, Scopus, and Google Scholar, were searched using relevant keywords. Once the authors were in agreement regarding the suitability of a study, a full-length form of the relevant article was obtained, and the information was gathered and cited. All the complete articles that were incorporated after the literature collection rejection criteria were applied were perused in-depth and material was extracted based on the importance, relevance, and advancement of the apprehending of the JAK/STAT pathway and their relation to phytochemicals. Based on the critical and comprehensive analysis of literature presented in this review, phytochemicals from diverse plant origins exert therapeutic and cancer preventive effects, at least in part, through regulation of the JAK/STAT pathway. Nevertheless, more preclinical and clinical research is necessary to completely comprehend the capability of modulating JAK/STAT signaling to achieve efficient cancer control and treatment.

NHC-gold compounds mediate immune suppression through induction of AHR-TGFβ1 signalling in vitro and in scurfy mice

Gold compounds have a long history of use as immunosuppressants, but their precise mechanism of action is not completely understood. Using our recently developed liver-on-a-chip platform we now show that gold compounds containing planar N-heterocyclic carbene (NHC) ligands are potent ligands for the aryl hydrocarbon receptor (AHR). Further studies showed that the lead compound (MC3) activates TGFβ1 signaling and suppresses CD4+ T-cell activation in vitro, in human and mouse T cells. Conversely, genetic knockdown or chemical inhibition of AHR activity or of TGFβ1-SMAD-mediated signaling offsets the MC3-mediated immunosuppression. In scurfy mice, a mouse model of human immunodysregulation polyendocrinopathy enteropathy X-linked syndrome, MC3 treatment reduced autoimmune phenotypes and extended lifespan from 24 to 58 days. Our findings suggest that the immunosuppressive activity of gold compounds can be improved by introducing planar NHC ligands to activate the AHR-associated immunosuppressive pathway, thus expanding their potential clinical application for autoimmune diseases.

Inhibitory effects of indirubin-3'-monoxime against human osteosarcoma

Indirubin is widely used as the active component of "Dangui Luhui Wan" in ancient China. However, its effects against the osteosarcoma (OS), the most common primary malignancy, are still unknown. In our present study, we investigated the effects of the Indirubin-3'-monoxime (I3M), a derivative of indirubin with better water solubility, against the OS cells. We found I3M inhibited OS cell proliferation in a dose-dependent manner. Flow cytometry assays showed that I3M could not only induce OS cell apoptosis in a time- and dose-dependent manner but also regulate the cell cycle distribution. Additionally, we demonstrated that several Bcl-2 family members, cyclin-dependent kinases (CDKs) and cyclins contributed to this process. Furthermore, out data verified that I3M suppressed OS cell migration and invasion by decreasing MMP-2 and MMP-9 levels. Moreover, survivin and focal adhesion kinase (FAK) might play important roles in the anti-OS effects of I3M. The administration of I3M also inhibited the OS cell growth in mice. Taken together, our results indicated the inhibitory effects of I3M against human OS and thus might be an efficient candidate for OS chemotherapy.

Indirubin derivatives are potent and selective anti-Trypanosoma cruzi agents

Current treatment for combatting Chagas disease, a life-threatening illness caused by the kinetoplastid protozoan parasite Trypanosoma cruzi is inadequate, and thus the discovery of new antiparasitic compounds is of prime importance. Previous studies identified the indirubins, a class of ATP kinase inhibitors, as potent growth inhibitors of the related kinetoplastid Leishmania. Herein, we evaluated the inhibitory activity of a series of 69 indirubin analogues screened against T. cruzi trypomastigotes and intracellular amastigotes. Seven indirubins were identified as potent T. cruzi inhibitors (low μΜ, nM range). Cell death analysis of specific compounds [3'oxime-6-bromoindirubin(6-BIO) analogues 10, 11 and 17, bearing a bulky extension on the oxime moiety and one 7 substituted analogue 32], as evaluated by electron microscopy and flow cytometry, showed a different mode of action between compound 32 compared to the three 6-BIO oxime- substituted indirubins, suggesting that indirubins may kill the parasite by different mechanisms dependent on their substitution. Moreover, the efficacy of four compounds that show the most potent anti-parasitic effect in both trypomastigotes and intracellular amastigotes (10, 11, 17, 32), was evaluated in a mouse model of T. cruzi infection. Compound 11 (3ʹpiperazine-6-BIO) displayed the best in vivo efficacy (1/6 mortality, 94.5% blood parasitaemia reduction, 12 dpi) at a dose five times reduced over the reference drug benznidazole (20 mg/kg vs100 mg/kg). We propose 3ʹpiperazine-6-BIO as a potential lead for the development of new treatments of Chagas disease.

Essential role of mitochondrial Stat3 in p38MAPK mediated apoptosis under oxidative stress

Stat3 is an oncogene, frequently associated with malignant transformation. A body of evidence implicates that phospho-Stat3^Y705 contributes to its nucleic translocation, while phospho-Stat3^S727 leads to the accumulation in mitochondria. Both are of importance for tumor cell proliferation. In comparison to well-characterized signaling pathways interplaying with Stat3^Y705, little is known about Stat3^S727. In this work, we studied the influence of Stat3 deficiency on the viability of cells exposed to H₂O₂ or hypoxia using siRNA and CRISPR/Cas9 genome-editing. We found dysregulation of mitochondrial activity, which was associated with excessive ROS formation and reduced mitochondrial membrane potential, and observed a synergistic effect for oxidative stress-mediated apoptosis in Stat3-KD cells or cells carrying Stat3^Y705F, but not Stat3^S727D, suggesting the importance of functional mitochondrial Stat3 in this context. We also found that ROS-mediated activation of ASK1/p38^MAPK was involved and adding antioxidants, p38^MAPK inhibitor, or genetic repression of ASK1 could easily rescue the cellular damage. Our finding reveals a new role of mitochondrial Stat3 in preventing ASK1/p38^MAPK-mediated apoptosis, wich further support the notion that selective inhibition mitochondrial Stat3 could provide a primsing target for chemotherapy.

Methylisoindigo and Its Bromo-Derivatives Are Selective Tyrosine Kinase Inhibitors, Repressing Cellular Stat3 Activity, and Target CD133+ Cancer Stem Cells in PDAC

Indirubin is an active component of the herbal ingredient ‘Danggui Longhui wan’, which was used for the treatment of inflammation and chronic myeloid leukemia in China. The recent study showed its derivative methylisoindigo (also known as meisoindigo) preferentially targeting cancer stem cells (CSCs) in interference with AMPK and LKB1, the cellular metabolic sensors. In this study, we screened the effect of meisoindigo on a panel of 300 protein kinases and found that it selectively inhibited Stat3-associated tyrosine kinases and further confirmed its activity in cell based assays. To gain a deeper insight into the structure–activity relationship we produced 7 bromo-derivatives exhausting the accessible positions on the bisindole backbone except for in the 4-position due to the space limitation. We compared their anti-proliferative effects on tumor cells. We found that 6-bromomeisoindigo showed improved toxicity in company with increased Stat3 inhibition. Moreover, we detected that 6-bromomeisoindigo induced apoptosis of 95% of CD133+ pancreatic cancer cells. Considering that CD133 is a common marker highly expressed in a range of CSCs, our results imply the potential application of 6-bromomeisoindigo for the treatment of CSCs in different types of cancers.

Pivotal roles of glycogen synthase-3 in hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is one of the most common cancers in the world, and represents the second most frequently cancer and third most common cause of death from cancer worldwide. At advanced stage, HCC is a highly aggressive tumor with a poor prognosis and with very limited response to common therapies. Therefore, there is still the need for new effective and well-tolerated therapeutic strategies. Molecular-targeted therapies hold promise for HCC treatment. One promising molecular target is the multifunctional serine/threonine kinase glycogen synthase kinase 3 (GSK-3). The roles of GSK-3β in HCC remain controversial, several studies suggested a possible role of GSK-3β as a tumor suppressor gene in HCC, whereas, other studies indicate that GSK-3β is a potential therapeutic target for this neoplasia. In this review, we will focus on the different roles that GSK-3 plays in HCC and its interaction with signaling pathways implicated in the pathogenesis of HCC, such as Insulin-like Growth Factor (IGF), Notch, Wnt/β-catenin, Hedgehog (HH), and TGF-β pathways. In addition, the pivotal roles of GSK3 in epithelial-mesenchymal transition (EMT), invasion and metastasis will be also discussed.

Identification of a Water-Soluble Indirubin Derivative as Potent Inhibitor of Insulin-like Growth Factor 1 Receptor through Structural Modification of the Parent Natural Molecule

Indirubins have been identified as potent ATP-competitive protein kinase inhibitors. Structural modifications in the 5- and 3'-position have been extensively investigated, but the impact of substituents in 5'-position is not equally well-studied. Here, we report the synthesis of new indirubin 3'- and 5'-derivatives in the search of water-soluble indirubins by introducing basic centers. Antiproliferative activity of all compounds in tumor cells was evaluated along with kinase inhibition of selected compounds. The results show the 3'-position to tolerate large substituents without compromising activity, whereas bulk and rigid substituents in 5'-position appear unfavorable. Screening molecular targets of water-soluble 3'-oxime ethers revealed 6ha as preferential inhibitor of insulin-like growth factor 1 receptor (IGF-1R) in a panel of 22 protein kinases and in cells. Consistently, 6ha inhibited tumor cell growth in the NCI 60 cell line panel and induced apoptosis. The results indicate that the 5'-position provides limited space for chemical modifications and identify 6ha as a potent water-soluble indirubin-based IGF-1R inhibitor.