Structurally novel steroidal spirooxindole by241 potently inhibits tumor growth mainly through ROS-mediated mechanisms

1,3-Dipolar cycloaddition reactions of isatin-derived azomethine ylides for the synthesis of spirooxindole and indole-derived scaffolds: recent developments

The unique therapeutic and biological characteristics of spirooxindole have led to the presentation of numerous reactions for the synthesis of spirooxindoles through 1,3-Dipolar cycloaddition of highly reactive isatin-derived azomethine ylides with activated olefins as the main tool for the formation of spirocyclic oxindoles during the last 4 years. Therefore, there is a need to highlight the recent developments in this area, along with the representative synthetic methods and relevant reaction mechanisms from 2018 to 2021. The representative synthetic methodologies were listed in four sections based on the procedure to form the azomethine ylide species including isatins and amino acids, isatin-derived α-(trifluoromethyl)imine, isatins and benzylamines, and from isatin-derived cyclic imine 1,3-dipoles.

A triphenylphosphine coordinated cinnamaldehyde-derived copper(I) Fenton-like agent with mitochondrial aggregation damage for chemodynamic therapy

Chemodynamic therapy (CDT), which uses agents to induce cell death by decomposing endogenous hydrogen peroxide (H₂O₂) into highly toxic hydroxyl radicals (˙OH), has been recognized as a promising approach to treat cancer. However, improving the efficiency of ˙OH production is considered one of the biggest challenges that limits the therapeutic efficacy of CDT. Herein, to controllably and efficiently induce oxidative damage through the production of ˙OH, we developed a new metal complex CDT agent with atomically precise structural characteristics as a deviation from traditional nanomaterial-CDT agents. The obtained CDT agent, a cinnamaldehyde derived copper(I) complex (denoted Cin-OD-Cu), was found to be continuously enriched in the mitochondria of A2780 ovarian carcinoma cells, which was accompanied by the generation of large amounts of ˙OH via Cu(I)-mediated Fenton-like reactions of H₂O₂, thereby stimulating oxidative stress in the mitochondria and eventually leading to cell death. Moreover, in vivo experiments showed that Cin-OD-Cu was capable of effectively inhibiting tumor growth with excellent biocompatibility. We believe this research enriches the limited selection of atomically precise metal complex CDT agents in particular for reactive oxygen species-mediated treatments aimed at inducing mitochondria oxidative damage; we anticipate that it will provide new insights into the development of novel, atomically precise agents for CDT.

Three-Component [3+2] Cycloaddition for Regio- and Diastereoselective Synthesis of Spirooxindole-Pyrrolidines

1,3-Dipolar cycloaddition of nonstabilized azomethine ylides derived from α-C-H functionalization of tetrahydroisoquinoline for regio- and diastereoselective synthesis of spirooxindole-pyrrolidines is developed. A three-component reaction of readily available cyclic amine, aryl aldehydes, and olefinic oxindoles provides a pot, atom and step economy (PASE) approach for making spiro-heterocyclic compounds with biological interest.

Combinative treatment of Curdione and docetaxel triggers reactive oxygen species (ROS)-mediated intrinsic apoptosis of triple-negative breast cancer cells

Traditional Chinese medicine Curcuma zedoary has been used for treating various diseases and cancers. However, the therapeutic effect of Curdione, one of its major components in triple negative breast cancer (TNBC) is still obscure. This study is aimed to explore whether combination of Curdione and docetaxel (DTX) could strengthen the DTX-induced pro-apoptotic effects in TNBC cells and identify its involved signaling pathways. In this study, combination of Curdione and DTX intensified the inhibited MDA-MB-468 cell proliferation and increased cell apoptosis caused by DTX treatment alone. Moreover, the combinative treatment of Curdione and DTX synergistically potentiated DTX-induced cell apoptosis by triggering reactive oxygen species (ROS) generation. Co-treatment with NAC (ROS inhibitor) could mostly block the effects induced by combination of Curdione and DTX. SB203580 (p38 inhibitor) or SC-79 (Akt activator) could partly reverse the effects induced by co-treatment, indicating that mitogen-actived protein kinases (MAPKs) and the phosphatidylinositol 3-kinases (PI3K) /Akt signaling pathway were involved in the co-treatment induced ROS-mediated cell apoptosis. To sum up, combination of Curdione and DTX enhanced the chemotherapeutic efficacy on MDA-MB-468 cells by triggering ROS-mediated cell apoptosis via MAPKs and PI3K/Akt signaling pathways. Curdione combined with DTX might have potentials application as the therapeutic strategy for TNBC.

New imidazo[2,1-b]thiazole-based aryl hydrazones: unravelling their synthesis and antiproliferative and apoptosis-inducing potential

Herein, we have designed and synthesized new imidazo[2,1-b]thiazole-based aryl hydrazones (9a-w) and evaluated their anti-proliferative potential against a panel of human cancer cell lines. Among the synthesized compounds, 9i and 9m elicited promising cytotoxicity against the breast cancer cell line MDA-MB-231 with IC50 values of 1.65 and 1.12 μM, respectively. Cell cycle analysis revealed that 9i and 9m significantly arrest MDA-MB-231 cells in the G0/G1 phase. In addition, detailed biological studies such as annexin V-FITC/propidium iodide, DCFH-DA, JC-1 and DAPI staining assays revealed that 9i and 9m triggered apoptosis in MDA-MB-213 cells. Overall, the current work demonstrated the cytotoxicity and apoptosis-inducing potential of 9i and 9m in breast cancer cells and suggested that they could be explored as promising antiproliferative leads in the future.

2-(6-Hydroxyhexylthio)-5,8-dimethoxy-1,4-naphthoquinone Induces Apoptosis through ROS-Mediated MAPK, STAT3, and NF-κB Signalling Pathways in Lung Cancer A549 Cells

Two novel compounds, 2-(2-hydroxyethylthio)-5,8-dimethoxy-1,4-naphthoquinone (HEDMNQ) and 2-(6-hydroxyhexylthio)-5,8-dimethoxy-1,4-naphthoquinone (HHDMNQ), were synthesized to investigate the kill effects and mechanism of 1,4-naphthoquinone derivatives in lung cancer cells. The results of the CCK-8 assay showed that HEDMNQ and HHDMNQ had significant cytotoxic effects on A549, NCI-H23, and NCI-H460 NSCLC cells. Flow cytometry and western blot results indicated that HHDMNQ induced A549 cell cycle arrest at the G2/M phase by decreasing the expression levels of cyclin-dependent kinase 1/2 and cyclin B1. Fluorescence microscopy and flow cytometry results indicated that HHDMNQ could induce A549 cell apoptosis, and western blot analysis showed that HHDMNQ induced apoptosis through regulating the mitochondria pathway, as well as the MAPK, STAT3, and NF-κB signalling pathways. Flow cytometry results showed that intracellular reactive oxygen species (ROS) levels were increased after HHDMNQ treatment, and western blot showed that ROS could modulate the intrinsic pathway and MAPK, STAT3, and NF-κB signalling pathways. These effects were blocked by the ROS inhibitor N-acetyl-L-cysteine in A549 cells. Our findings suggest that compared with HEDMNQ, HHDMNQ had the stronger ability to inhibit the cell viability of lung cancer cells and induce apoptosis by regulating the ROS-mediated intrinsic pathway and MAPK/STAT3/NF-κB signalling pathways. Thus, HHDMNQ might be a potential antitumour compound for treating lung cancer.

Thiosemicarbazone-based lead optimization to discover high-efficiency and low-toxicity anti-gastric cancer agents

In this paper, a series of thiosemicarbazone derivatives containing different aromatic heterocyclic groups were synthesized and the tridentate donor system of the lead compound was optimized. Most of the target compounds showed improved antiproliferative activity against MGC803 cells. SAR studies revealed that compound 5d displayed significant advantages in inhibition effect with an IC₅₀ value of 0.031 μM, and better selectivity between cancer and normal cells than 3-AP and DpC (about 15- and 5-fold improved respectively). Besides, compound 5d showed selective antiproliferative activity in not only other cancer cells but also different gastric cancer cell lines. In-depth mechanism studies showed that compound 5d could induce mitochondria-related apoptosis which might be related to the elevation of intracellular ROS level, and cause cell cycle arrest at S phase. Moreover, 5d could evidently suppress the cell migration and invasion by blocking the EMT (epithelial-mesenchymal transition) process. Consequently, our studies provided a lead optimization strategy of thiosemicarbazone derivatives which would contribute to discover high-efficiency and low-toxicity agents for the treatment of gastric cancer.

Regioselective synthesis and evaluation of 2-amino 3-cyano chromene-chrysin hybrids as potential anticancer agents

The first example of Ca(OH)₂-activated p-regioselective synthesis of chrysin-fused chromene was reported through a cascade Michael/cyclization of chrysin and arylidenemalononitrile. The newly synthesized structurally diverse 2-amino 3-cyano chromene-chrysin hybrids 3 were evaluated for their in vitro anticancer activity, and some of the compounds showed stronger anti-proliferative activity against K562, PC-3, A549 and NCI-H1299 than parent compound chrysin, and demonstrated equipotent potency compared with the reference drug of cisplatin. In particular, compound 3h had the highest cytotoxicity towards K562 cells (IC₅₀ = 6.41 µM). Furthermore, compound 3h induced apoptosis of K562 cells in a concentration-dependent manner, as well as induced the apoptosis possibly through promoting the formation of apoptotic DNA of cancer cell via the intrinsic apoptotic pathway. Thus, our results provide in vitro evidence that compound 3h may be a potential candidate for the development of new anti-tumour drugs.

An overview of spirooxindole as a promising scaffold for novel drug discovery

Introduction: Spirooxindole, a unique and versatile scaffold, has been widely studied in some fields such as pharmaceutical chemistry and synthetic chemistry. Especially in the application of medicine, quite a few compounds featuring spirooxindole motif have displayed excellent and broad pharmacological activities. Many identified candidate molecules have been used in clinical trials, showing promising prospects.Areas covered: This article offers an overview of different applications and developments of spirooxindoles (including the related natural products and their derivatives) in the process of drug innovation, including such as in anticancer, antimicrobial, anti-inflammatory, analgesic, antioxidant, antimalarial, and antiviral activities. Furthermore, the crucial structure-activity relationships, molecular mechanisms, pharmacokinetic properties, and main synthetic methods of spirooxindoles-based derivatives are also reviewed.Expert opinion: Recent progress in the biological activity profiles of spirooxindole derivatives have demonstrated their significant position in present-day drug discovery. Furthermore, we believe that the multidirectional development of novel drugs containing this core scaffold will continue to be the research hotspot in medicinal chemistry in the future.

Synthesis of new steroidal quinolines with antitumor properties

The incorporation of the heterocycles into the steroid nucleus has been recognized as a useful strategy to develop new steroidal agents for disease treatment. Representative examples are abiraterone and galeterone, which are presently used in clinic for the treatment of advanced prostate cancers. Herein we have developed the first Al₂O₃/KF-promoted pfitzinger reactions for the synthesis of new steroidal quinolines. These new steroidal quinolines showed moderate to good antiproliferative activity against several human lung cancer cells. Of these compounds, compound 2f exhibited the best potency toward the tested three lung cancer cells with IC₅₀ values <10 μM. Mechanistic studies showed that compound 2f concentration-dependently inhibited colony formation, morphological changes, apoptosis, and migration of A549 cells. To conclude, compound 2f could be used as a hit compound for developing steroid-based anti-lung cancer agents.

Design, synthesis and biological evaluation of new steroidal β-triazoly enones as potent antiproliferative agents

β-Triazoly enones are biologically interesting scaffolds, incorporation of such scaffolds into the steroid nucleus may generate new bioactive steroids and further enrich structural types of steroids. In this work, a series of new steroidal β-triazoly enones were synthesized based on click chemistry and Claisen-Schmidt condensation reaction and further evaluated for their antiproliferative activity against a panel of cancer cells. Most of these compounds showed better potency against PC-3 and MGC-803 cells. Particularly, compound 5a inhibited PC-3 and MGC-803 cells potently with the IC₅₀ values of 1.61 and 1.16 μM, respectively, and was less toxic toward GES-1 with an IC₅₀ value of 20.72 μM. Further mechanistic studies showed that compound 5a inhibited migration and invasion of MGC-803 and PC-3 dose-dependently. Treatment with compound 5a varied mRNA levels and protein expression of EMT markers in both cells. Collectively, the steroidal β-triazoly enones could be potentially utilized to develop new anticancer agents with the ability of inhibiting cell migration and invasion.

Synthesis and biological evaluation of vanadium complexes as novel anti-tumor agents

A class of vanadium complexes were prepared and investigated for their antiproliferative effects by MTT assay. The structure-activity relationship was extensively studied through the ligand variation. The results showed that the synthetic vanadium complexes demonstrated moderate to good antiproliferative activities against the four cancer cell lines including MGC803, EC109, MCF7 and HepG2, respectively. Of note was that most of the complexes showed preferential growth inhibitory activity to some degree toward gastric cancer line MGC803. Among them, complex 19 exhibited the most and broad-spectrum proliferative inhibition against the tested cell lines. In addition, mechanism studies illustrated that complex 19 could prevent the colony formation, migration and EMT process, as well as induce apoptosis of MGC803 cells. Furthermore, Western blot experiments revealed that the expression of apoptosis-related proteins changed, including up-regulation of Bax, PARP and caspase-3/9, as well as down-regulation of Bcl-2.

Synthesis and X-ray study of dispiro 8-nitroquinolone analogues and their cytotoxic properties against human cervical cancer HeLa cells

A series of unique dispiro analogues containing an oxindole pyrrolidine 8-nitroquinolone hybrid has been obtained through a one-pot three-component 1,3-dipolar cycloaddition of azomethine ylides generated in situ from the condensation of isatins and benzylamine with (E)-3-arylidene-2,3-dihydro-8-nitro-4-quinolones. The structures of the newly synthesized compounds were characterized by using different spectroscopic techniques and by X-ray diffraction studies of their regio- and stereochemistry. All the synthesized compounds were screened for in vitro cytotoxic activity against the human cervical cancer cell line HeLa. The compounds have exhibited potent inhibition against human cervical cancer cells and insignificant toxicity to normal cells. The compounds 6d, 6a, 6h, 6b, and 6e induced apoptosis of HeLa cells, through ROS influx. The expression levels of proteins involved in the mitochondrion-related pathways were detected, and Western blot analysis showed that apoptosis occurred via activation of caspase-3.

Discovery of a non-toxic [1,2,4]triazolo[1,5-a]pyrimidin-7-one (WS-10) that modulates ABCB1-mediated multidrug resistance (MDR)

Multidrug resistance (MDR) has been shown to reduce the effectiveness of chemotherapy. Strategies to overcoming MDR have been widely explored in the last decades, leading to a generation of numerous small molecules targeting ABC and MRP transporters. Among the ABC family, ABCB1 plays key roles in the development of drug resistance and is the most well studied. In this work, we report the discovery of non-toxic [1,2,4]triazolo[1,5-a]pyrimidin-7-one (WS-10) from our structurally diverse in-house compound collection that selectively modulates ABCB1-mediated multidrug resistance. WS-10 enhanced the intracellular accumulation of paclitaxel in SW620/Ad300 cells, but did not affect the expression of ABCB1 Protein and ABCB1 localization. The cellular thermal shift assay (CETSA) showed that WS-10 was able to bind to ABCB1, which could be responsible for the reversal effect of WS-10 toward paclitaxel and doxorubicin in SW620/Ad300 cells. Docking simulations were performed to show the possible binding modes of WS-10 within ABCB1 transporter. To conclude, WS-10 could be used as a template for designing new ABCB1 modulators to overcome ABCB1-mediated multidrug resistance.

Brevilin A promotes oxidative stress and induces mitochondrial apoptosis in U87 glioblastoma cells

Background

Sesquiterpene lactones are plant-derived, natural, bioactive molecules often used against inflammatory diseases in traditional Chinese medicines. Recently, sesquiterpene lactones have been reported to exhibit potent anticancer activity. In the present study, we have investigated the anticancer activity of Brevilin A, a sesquiterpene lactone component of Centipeda minima, against U87 glioblastoma cells.

Materials and methods

The cell proliferation was determined by MTT assay. Cell morphological changes were observed by phase-contrast microscopy. Flow cytometry was used to measure apoptosis. Glutathione (GSH), ROS generation, and mitochondrial membrane potential were measured using commercially available kits. The expression of proteins was measured by Western blotting analysis.

Results

Brevilin A inhibited the proliferation of, and induced severe morphological changes and apoptotic cell death in, U87 glioblastoma cells in a dose-dependent manner. Further mechanistic study revealed that Brevilin A induces oxidative stress, as evident from ROS generation, GSH depletion, and increased phosphorylation of stress-activated proteins p38 and JNK. Furthermore, Brevilin A bcl-xl/bak ratio, decreased mitochondrial membrane potential and induced cytochrome c release from mitochondria into cytosol in a dose-dependent manner. Finally, Brevilin A decreased the expression of Xiap and increased the expression of cleaved forms of caspase-9 and -3 and PARP in a dose-dependent manner.

Conclusion

Collective findings demonstrated that Brevilin A is a potent, anticancer, bioactive molecule and it effectively induces apoptosis in U87 glioblastoma cells, which is associated with induction of oxidative stress and mitochondrial dysfunction.

Multi-targeted therapy of everolimus in Kaposi's sarcoma associated herpes virus infected primary effusion lymphoma

Kaposi's sarcoma associated herpes virus (KSHV) infected primary effusion lymphoma (PEL) is a rare aggressive form of non-Hodgkin's lymphoma of B cells. KSHV latent and lytic antigens modulate several host cellular signalling pathways especially mammalian target of rapamycin (mTOR), STAT-3 and nuclear factor-kappa B (NF-κB) for rapid tumor progression and immune evasion. Current chemotherapeutic strategies are becoming ineffective as they kill only dividing cells and inefficient to target molecular pathways crucial for active virus replication and its survival. In this study, we evaluated the efficacy of everolimus, an mTOR inhibitor in inducing apoptosis of PEL cells. Dose-dependent treatment of everolimus triggered mitochondria-mediated caspase-dependent apoptosis in PEL cells. Everolimus downregulated KSHV latent antigen expression with concurrent blocking of lytic reactivation for active virus replication. Everolimus also inhibited latent antigen mediated constitutively active STAT-3 and NF-κB signalling. We co-cultured everolimus treated PEL cells with immature dendritic cells and found activation of dendritic cells with increase in surface expression of CD86 and HLA-DR. As everolimus targets and disrupts KSHV antigens as well as antigen facilitated multiple signalling pathways necessary for KSHV survival and maintenance of infection with synchronised boosting of immune system against viral infection, it can be a better therapeutic approach towards treatment of PEL.

Evaluation of In Vitro Antioxidant and Anticancer Properties of the Aqueous Extract from the Stem Bark of Stryphnodendron adstringens

Stryphnodendron adstringens (Mart.) Coville (Fabaceae) is a tree species native to the Brazilian Cerrado commonly known as barbatimão. In traditional medicine, decoctions or infusions of the stem bark of this plant are used in the treatment of several diseases. The objective of this study was to analyze the chemical composition of Stryphnodendron adstringens aqueous extracts (SAAE) prepared from the stem bark to assess their antioxidant activity and anticancer effects as well as characterize cell death mechanisms against murine B16F10Nex-2 melanoma cells. From the SAAE, gallic acid, gallocatechin, epigallocatechin, dimeric and trimeric proanthocyanidins mainly composed of prodelphinidin units and the isomeric chromones C-hexosyl- and O-pentosyl-5,7-dihydroxychromone were identified. The SAAE showed antioxidant activity through direct free-radical scavenging as well as through oxidative hemolysis and lipid peroxidation inhibition in human erythrocytes. Furthermore, SAAE promoted apoptosis-induced cell death in melanoma cells by increasing intracellular reactive oxygen species (ROS) levels, inducing mitochondrial membrane potential dysfunction and activating caspase-3. Together, these data show the antioxidant and anticancer effects of Stryphnodendron adstringens. These results open new perspectives for studies against other tumor cell lines and in vivo models as well as for the identification and isolation of the chemical constituents responsible for these effects.

Discovery of 6-chloro-2-(propylthio)-8,9-dihydro-7H-purines containing a carboxamide moiety as potential selective anti-lung cancer agents

A new series of 6-chloro-2-(propylthio)-8,9-dihydro-7H-purine-8-caboxamide derivatives were designed, synthesized, and further evaluated for their antiproliferative activities on four human cancer cell lines (A549, MGC803, PC-3 and TE-1). The structure-activity relationships (SARs) studies were conducted through the variation in the two regions, which including position 8 and 9, of purine core. One of the compounds, 8, containing a terminal piperazine appendage with a carboxamide moiety at position 8 and phenyl group at position 9 of 6-chloro-8,9-dihydro-7H-purine core, showed the most potent antiproliferative activity and good selectivity between cancer and normal cells (IC₅₀ values of 2.80 μM against A549 and 303.03 μM against GES-1, respectively). In addition, compound 8 could inhibit the colony formation and migration of A549 cells in a concentration-dependent manner, as well as induce the apoptosis possibly through the intrinsic pathway.

Synthesis of unprecedented steroidal spiro heterocycles as potential antiproliferative drugs

Herein we report the straightforward preparation of novel conformationally-restricted steroids from trans-androsterone and estrone, decorated with spiranic oxazolidin-2-one or 2-aminooxazoline motifs at C-17 as potential antiproliferative agents. Such unprecedented pharmacophores were accessed using an aminomethylalcohol derivative at C-17 as the key intermediate; reaction of such functionality with triphosgene, or conversion into N-substituted thioureas, followed by an intramolecular cyclodesulfurization reaction promoted by yellow HgO, furnished such spirocycles in excellent yields. Title compounds were tested in vitro against a panel of six human tumor cell lines, named A549 (non-small cell lung), HBL-100 (breast), HeLa (cervix), SW1573 (non-small cell lung), T-47D (breast) and WiDr (colon), and the results were compared with steroidal chemotherapeutic agents (abiraterone and galeterone); the A-ring of the steroidal backbone, the nature of the heterocycle and the N-substituents proved to be essential motifs for establishing structure-activity relationships concerning not only the potency but also the selectivity against tumor cell lines. Estrone derivatives, particularly those bearing a spiranic 2-aminooxazoline scaffold were found to be the most active compounds, with GI₅₀ values ranging from the low micromolar to the submicromolar level (0.34-1.5 μM). Noteworthy, the lead compounds showed a remarkable increase in activity against the resistant cancer cell lines (T-47D and WiDr) compared to the anticancer reference drugs (up to 120-fold).

Design, synthesis, and biological evaluation of new thiazolo[5,4-d]pyrimidine derivatives as potent antiproliferative agents

A series of thiazolo[5,4-d]pyrimidine derivatives were synthesized and evaluated for their antiproliferative activities against several human cancer cell lines. Structure-activity relationship studies were carried out, showing that most of the target compounds had good inhibition against the tested cell lines. Among them, compound 7i exhibited potent inhibition against human gastric cancer cells MGC-803 and HGC-27 with IC50 values of 4.64 and 5.07 μM, respectively and around 12-fold selectivity between MGC-803 and GES-1, indicating a relatively low toxicity to normal cells. The potency and low toxicity of compound 7i make the thiazolo[5,4-d]pyrimidine an attractive scaffold for designing new derivatives selectively targeting MGC-803 cells.

Alantolactone induces apoptosis, promotes STAT3 glutathionylation and enhances chemosensitivity of A549 lung adenocarcinoma cells to doxorubicin via oxidative stress

Alantolactone (ALT), a sesquiterpene lactone component of Inula helenium, has been reported to exert anticancer activity in various cancers. However, the cellular targets and underlying mechanism of anticancer activity of ALT in various cancers including lung cancer has not been fully defined. In the present study, we found that ALT effectively inhibits proliferation and triggers oxidative stress mediated-apoptosis in A549 lung adenocarcinoma cells by inducing ER stress and mitochondrial dysfunction. This ALT-mediated apoptosis was inhibited by NAC while diamide potentiated it. Moreover, ALT effectively suppressed both constitutive and inducible STAT3 activation, inhibited its translocation into nucleus and decreased its DNA binding activity. Further mechanistic study revealed that ALT abrogated STAT3 activation by promoting STAT3 glutathionylation. ROS scavenger NAC reverted ALT-mediated STAT3 glutathionylation and inhibition of STAT3 phosphorylation. Finally, ALT enhanced chemosensitivity of A549 cells to doxorubicin and reversed doxorubicin resistance in A549/DR cells by inhibiting STAT3 activation and P-glycoprotein expression and increasing intracellular accumulation of doxorubicin. Suppression of STAT3 activation by targeting ROS metabolism with ALT thus discloses a previously unrecognized mechanism underlying the biological activity of ALT. Taken together; ALT induces oxidative stress-dependent apoptosis, inhibits STAT3 activation and augments doxorubicin toxicity in A549 lung cancer cells. These findings provide an in-depth insight into the molecular mechanism of ALT in the treatment of lung cancer.

Design, synthesis and antiproliferative activity of thiazolo[5,4-d]pyrimidine derivatives through the atom replacement strategy

A series of thiazolo[5,4-d]pyrimidine derivatives were designed through the atom replacement strategy based on biologically validated scaffolds and then evaluated for their antiproliferative activities on cancer cell lines. The structure-activity relationship studies were conducted, leading to the identification of compound 22, which exhibited good antiproliferative activity against HGC-27 with an IC₅₀ value of 1.22 μM and low toxicity against GES-1 cells. Mechanistic studies showed that compound 22 inhibited the colony formation and migration of HGC-27 as well as induced apoptosis. The western blot experiments proved that compound 22 up-regulated expression of Bax, down-regulated expression levels of Bcl-2 and cleaved caspased-3/9. These findings indicate that compound 22 may serve as a template for designing new agents for the treatment of human gastric cancers. The atom replacement strategy could be viable strategy for designing new anticancer drugs and may find its applications in drug design.

Identification of thiazolo[5,4-d]pyrimidine derivatives as potent antiproliferative agents through the drug repurposing strategy

A series of thiazolo[5,4-d]pyrimidine derivatives were synthesized and evaluated for their antiproliferative activities on three cancer cell lines. The structure-activity relationship studies were conducted through the variation in the three regions of the thiazolo-pyrimidine core. Substitution with morpholine led to compound 24, which exerted the most potent antiproliferative activity as well as good selectivity between cancer and normal cells (IC₅₀ values of 1.03 μM against MGC803 and 38.95 μM against GES-1). In addition, compound 24 inhibited the colony formation and migration of MGC803 as well as induced apoptosis. Western blot experiments indicated the expression changes of apoptosis-related proteins, including up-regulation of Bax and caspase-3/9, as well as down-regulation of Bcl-2.