Suprafenacine, an indazole-hydrazide agent, targets cancer cells through microtubule destabilization

In silico approaches for drug repurposing in oncology: a scoping review

Introduction: Cancer refers to a group of diseases characterized by the uncontrolled growth and spread of abnormal cells in the body. Due to its complexity, it has been hard to find an ideal medicine to treat all cancer types, although there is an urgent need for it. However, the cost of developing a new drug is high and time-consuming. In this sense, drug repurposing (DR) can hasten drug discovery by giving existing drugs new disease indications. Many computational methods have been applied to achieve DR, but just a few have succeeded. Therefore, this review aims to show in silico DR approaches and the gap between these strategies and their ultimate application in oncology. Methods: The scoping review was conducted according to the Arksey and O'Malley framework and the Joanna Briggs Institute recommendations. Relevant studies were identified through electronic searching of PubMed/MEDLINE, Embase, Scopus, and Web of Science databases, as well as the grey literature. We included peer-reviewed research articles involving in silico strategies applied to drug repurposing in oncology, published between 1 January 2003, and 31 December 2021. Results: We identified 238 studies for inclusion in the review. Most studies revealed that the United States, India, China, South Korea, and Italy are top publishers. Regarding cancer types, breast cancer, lymphomas and leukemias, lung, colorectal, and prostate cancer are the top investigated. Additionally, most studies solely used computational methods, and just a few assessed more complex scientific models. Lastly, molecular modeling, which includes molecular docking and molecular dynamics simulations, was the most frequently used method, followed by signature-, Machine Learning-, and network-based strategies. Discussion: DR is a trending opportunity but still demands extensive testing to ensure its safety and efficacy for the new indications. Finally, implementing DR can be challenging due to various factors, including lack of quality data, patient populations, cost, intellectual property issues, market considerations, and regulatory requirements. Despite all the hurdles, DR remains an exciting strategy for identifying new treatments for numerous diseases, including cancer types, and giving patients faster access to new medications.

Chalcone-Acridine Hybrid Suppresses Melanoma Cell Progression via G2/M Cell Cycle Arrest, DNA Damage, Apoptosis, and Modulation of MAP Kinases Activity

This study was focused on investigating the antiproliferative effects of chalcone hybrids in melanoma cancer cells. Among seven chalcone hybrids, the chalcone-acridine hybrid 1C was the most potent and was selected for further antiproliferative mechanism studies. This in vitro study revealed the potent antiproliferative effect of 1C via cell cycle arrest and apoptosis induction. Cell cycle arrest at the G2/M phase was associated with modulation of expression or phosphorylation of specific cell cycle-associated proteins (cyclin B1, p21, and ChK1), tubulins, as well as with the activation of the DNA damage response pathway. Chalcone 1C also induced apoptosis accompanied by mitochondrial dysfunction evidenced by a decrease in mitochondrial membrane potential, increase in Bax/Bcl-xL ratio and cytochrome c release followed by caspase 3/7 activation. In addition, increased phosphorylation of MAP kinases (Erk1/2, p38 and JNK) was observed in chalcone 1C-treated melanoma cells. The strong antiproliferative activities of this chalcone-acridine hybrid suggest that it may be useful as an antimelanoma agent in humans.

Indazole-based microtubule-targeting agents as potential candidates for anticancer drugs discovery

Tremendous research is focused on developing novel drug candidates targeting microtubules to inhibit their function in several cellular processes, including cell division. In this regard, several indazole derivatives were sought to target the colchicine binding site on the β-tubulin, a crucial protein required to form microtubules, to develop microtubule targeting agents. Even though there are several reviews on the indazole-based compounds, none of them focused on using indazole scaffold to develop microtubule targeting agents. Therefore, this review aims to present the advances in research on compounds containing indazole scaffolds as microtubule targeting agents based on the articles published in the last two decades. Among the articles reviewed, we found that compounds 6 and 7 showed the lowest IC₅₀ values of 0.6 ∼ 0.9 nM in the cell line studies, making them the strongest indazole derivatives that target microtubules. The compounds 30, 31, 37 (IC₅₀ = ∼ 1 nM) and compounds 8, 38 (IC₅₀ = ∼ 2 nM) have proved to be potent microtubule inhibitors. The compounds 18, 31, 44, 45 also showed strong anticancer activity (IC₅₀ = ∼ 8 nM). It is important to notice that except for compounds 9, 12, 13, 15, and SRF, the top activity compounds including 6, 7, 8, 10, 11, 30, 31, 37, 44, and 45 contain 3,4,5‑trimethoxyphenyl substitution similar to that of colchicine. Therefore, it appears that the 3,4,5‑trimethoxyphenyl substituent on the indazole scaffold is crucial for targeting CBS.

A CTG repeat-selective chemical screen identifies microtubule inhibitors as selective modulators of toxic CUG RNA levels

A CTG repeat expansion in the DMPK gene is the causative mutation of myotonic dystrophy type 1 (DM1). Transcription of the expanded CTG repeat produces toxic gain-of-function CUG RNA, leading to disease symptoms. A screening platform that targets production or stability of the toxic CUG RNA in a selective manner has the potential to provide new biological and therapeutic insights. A DM1 HeLa cell model was generated that stably expresses a toxic r(CUG)480 and an analogous r(CUG)0 control from DMPK and was used to measure the ratio-metric level of r(CUG)480 versus r(CUG)0. This DM1 HeLa model recapitulates pathogenic hallmarks of DM1, including CUG ribonuclear foci and missplicing of pre-mRNA targets of the muscleblind (MBNL) alternative splicing factors. Repeat-selective screening using this cell line led to the unexpected identification of multiple microtubule inhibitors as hits that selectively reduce r(CUG)480 levels and partially rescue MBNL-dependent missplicing. These results were validated by using the Food and Drug Administration-approved clinical microtubule inhibitor colchicine in DM1 mouse and primary patient cell models. The mechanism of action was found to involve selective reduced transcription of the CTG expansion that we hypothesize to involve the LINC (linker of nucleoskeleton and cytoskeleton) complex. The unanticipated identification of microtubule inhibitors as selective modulators of toxic CUG RNA opens research directions for this form of muscular dystrophy and may shed light on the biology of CTG repeat expansion and inform therapeutic avenues. This approach has the potential to identify modulators of expanded repeat-containing gene expression for over 30 microsatellite expansion disorders.

Deoxypodophyllotoxin Exerts Anti-Cancer Effects on Colorectal Cancer Cells Through Induction of Apoptosis and Suppression of Tumorigenesis

Deoxypodophyllotoxin (DPT) is a cyclolignan compound that exerts anti-cancer effects against various types of cancers. DPT induces apoptosis and inhibits the growth of breast, brain, prostate, gastric, lung, and cervical tumors. In this study, we sought to determine the effect of DPT on cell proliferation, apoptosis, motility, and tumorigenesis of three colorectal cancer (CRC) cell lines: HT29, DLD1, and Caco2. DPT inhibited the proliferation of these cells. Specifically, the compound-induced mitotic arrest in CRC cells by destabilizing microtubules and activating the mitochondrial apoptotic pathway via regulation of B-cell lymphoma 2 (Bcl-2) family proteins (increasing Bcl-2 associated X (BAX) and decreasing B-cell lymphoma-extra-large (Bcl-xL)) ultimately led to caspase-mediated apoptosis. In addition, DPT inhibited tumorigenesis in vitro, and in vivo skin xenograft experiments revealed that DPT significantly decreased tumor size and tumor weight. Taken together, our results suggest DPT to be a potent compound that is suitable for further exploration as a novel chemotherapeutic for human CRC.

Microtubule inhibitor, SP-6-27 inhibits angiogenesis and induces apoptosis in ovarian cancer cells

In ovarian cancer (OVCA), treatment failure due to chemo-resistance is a serious challenge. It is therefore critical to identify new therapies that are effective against resistant tumors and have reduced side effects. We recently identified 4-H-chromenes as tubulin depolymerizing agents that bind to colchicine site of beta-tubulin. Here, we screened a chemical library of substituted 4-H-chromenes and identified SP-6-27 to exhibit most potent anti-proliferative activity towards a panel of human cisplatin sensitive and resistant OVCA cell lines with 50% inhibitory concentration (IC₅₀; mean ± SD) ranging from 0.10 ± 0.01 to 0.84 ± 0.20 μM. SP-6-27 exhibited minimum cytotoxicity to normal ovarian epithelia. A pronounced decrease in microtubule density as well as G2/M cell cycle arrest was observed in SP-6-27 treated cisplatin sensitive/resistant OVCA cells. The molecular mechanism of SP-6-27 induced cell death revealed modulation in cell-cycle regulation by upregulation of growth arrest and DNA damage inducible alpha transcripts (GADD45). An enhanced intrinsic apoptosis was observed in OVCA cells through upregulation of Bax, Apaf-1, caspase-6, -9, and caspase-3. In vitro wound healing assay revealed reduced OVCA cell migration upon SP-6-27 treatment. Additionally, SP-6-27 and cisplatin combinatorial treatment showed enhanced cytotoxicity in chemo-sensitive/resistant OVCA cells. Besides effect on cancer cells, SP-6-27 further restrained angiogenesis by inhibiting capillary tube formation by human umbilical vein endothelial cells (HUVEC). Together, these findings show that the chromene analog SP-6-27 is a novel chemotherapeutic agent that offers important advantages for the treatment of ovarian cancer.

Cytotoxic activity of a synthetic deoxypodophyllotoxin derivative with an opened D-ring

Podophyllotoxin and its synthetic derivatives are valuable medicinal agents that have antitumor, insecticidal, and antifungal properties. We previously synthesized a deoxypodophyllotoxin derivative with an opened D-ring (DPD) exhibiting potent insecticidal activity. This article was firstly performed to identify the cytotoxicity of DPD toward human cancer cell lines (SGC7901, HeLa, and A549) and normal cell line (HEK293T) using MTT assay. DPD showed potent cytotoxicity against human cancer lines (HeLa and A549) and less cytotoxicity against normal cell lines HEK293T. DPD could also induce the cell cycle arrest at G2/M phase in HeLa cells and significantly increase the phosphorylation (Tyr 15) of CDC2 leading to inactivation of CDC2. The effects of DPD on cellular microtubule networks were detected using immunofluorescence technique in HeLa cells. The immunofluorescence results showed DPD influenced the arrangement and organization of cellular microtubule networks in HeLa cells. Microtubules are long, hollow cylinders made up of polymerized tubulin dimers. Total microtubules were separated after DPD treatment. Western blot results showed that the free polymerized tubulin dimers were obviously increased after DPD treatment. DPD may be a good drug candidate with the therapeutic potential to human cancer by affecting microtubule polymerization.

Aminochrome Toxicity is Mediated by Inhibition of Microtubules Polymerization Through the Formation of Adducts with Tubulin

In this study, we investigated the role of adducts formation between aminochrome and tubulin and its interference in microtubules assembly and stability in aminochrome-induced toxicity in SH-SY5Y cells. We also investigated whether changes in the microtubules structures are an early event that could affect tubulin expression. We demonstrated in vitro that aminochrome tubulin adducts inhibit tubulin polymerization and that aminochrome induces microtubules disassembly. Moreover, when the SH-SY5Y cells were incubated with aminochrome, we observed an increase in soluble tubulin, indicating depolymerization of microtubules. Aminochrome generates disruption of the microtubules network, leading to changes in the morphology of the cells inducing cell death, in a dose- and time-dependent manner. Interestingly, these changes preceded cell death and were partly inhibited by paclitaxel, a microtubule-stabilizing agent. Furthermore, we observed that aminochrome increased early tubulin expression before significant cell death occurred. Consequently, all these antecedents suggest that aminochrome toxicity is mediated by early disruption of microtubules network, where the adduct formation between aminochrome and tubulin could be responsible for the inhibition in the assembly microtubules and the loss of microtubules stability. Possibly, the early changes in tubulin expression could correspond to compensatory mechanisms against the toxic effects of aminochrome.