Small molecules inhibit STAT3 activation, autophagy, and cancer cell anchorage-independent growth

Unveiling the role of Ndrg1 gene on the oxidative stress induction behind the anticancer potential of styrylquinazoline derivatives

This work presents a multifaceted mechanism of the anticancer action of a 2-styrylquinazoline derivative. Extensive analysis of various aspects related to tyrosine kinase inhibition and effects on cellular targets at both the gene and protein levels revealed the potential of this IS20 compound for future research. This study presents a detailed analysis of the relationship between ABL and SRC kinase affecting the inhibition of the EGFR/mTOR signaling pathway in a non-obvious manner. The study was supported by experiments using various molecular biology techniques to confirm the induction of oxidative stress, inhibition of the cell cycle in the G2/M phase and the triggering of cell death via both the apoptosis and autophagy pathways. The cell models included those with different p53 protein status, which affected the cellular response in the form of altered Ndrg1 expression. Finally, the appropriate physicochemical properties of IS20 for adequate bioavailability and toxicity to the body were observed in an in vivo model.

Small Molecules Targeting Programmed Cell Death in Breast Cancer Cells

Targeted chemotherapy has become the forefront for cancer treatment in recent years. The selective and specific features allow more effective treatment with reduced side effects. Most targeted therapies, which include small molecules, act on specific molecular targets that are altered in tumour cells, mainly in cancers such as breast, lung, colorectal, lymphoma and leukaemia. With the recent exponential progress in drug development, programmed cell death, which includes apoptosis and autophagy, has become a promising therapeutic target. The research in identifying effective small molecules that target compensatory mechanisms in tumour cells alleviates the emergence of drug resistance. Due to the heterogenous nature of breast cancer, various attempts were made to overcome chemoresistance. Amongst breast cancers, triple negative breast cancer (TNBC) is of particular interest due to its heterogeneous nature in response to chemotherapy. TNBC represents approximately 15% of all breast tumours, however, and still has a poor prognosis. Unlike other breast tumours, signature targets lack for TNBCs, causing high morbidity and mortality. This review highlights several small molecules with promising preclinical data that target autophagy and apoptosis to induce cell death in TNBC cells.

MORC4 Promotes Chemoresistance of Luminal A/B Breast Cancer via STAT3-Mediated MID2 Upregulation

Purpose

MORC4 has recently been characterized as a breast cancer-associated anti-apoptotic oncoprotein. In the current study, we explored its downstream regulation in luminal A/B breast tumors.

Materials and Methods

Bioinformatic prediction was performed using data from The Cancer Genome Atlas (TCGA)-breast cancer (BRCA). Cellular and molecular studies were conducted using luminal A/B representative MCF-7 and BT-474 cell lines.

Results

ENST00000355610.8 (encoding MORC4a isoform) was the dominant transcript in breast cancer. ChIP-qPCR and dual-luciferase assay confirmed two STAT3-binding sites in the MID2 promoter in both MCF-7 and BT-474 cells. Co-IP confirmed an interaction between MORC4 and STAT3. ChIP-qPCR data indicated that MORC4 inhibition led to remarkably decreased enrichment of the STAT3-binding MID2 promoter segments. MORC4 overexpression significantly elevated BCL-2 expression in MCF-7 cells and increased their resistance to adriamycin (ADM), 5-fluorouracil (5-FU), and cisplatin (DDP). MID2 inhibition largely abrogated MORC4-induced drug-resistance. However, the drug-resistant phenotype was rescued by overexpressing MID2-MT that was resistant to MID2 siRNA.

Conclusion

This study revealed a novel regulatory mechanism of MORC4 on MID2 expression via STAT3-mediated transcriptional activation. This regulatory axis might confer increased chemoresistance to breast cancer cells.

Critical Areas of Proliferation of Single Cells on Micropatterned Surfaces and Corresponding Cell Type Dependence

Material cues to influence cell proliferation are a fundamental issue in the fields of biomaterials, cell biology, tissue engineering, and regenerative medicine. This paper aims to investigate the proliferation of single mammal cells on micropatterned material surfaces. To this end, we prepared cell-adhesive circular microislands with 20 areas on the nonfouling background and systematically examined adhesion and proliferation behaviors of different kinds of single cells (primary stem and nonstem cells, cancer and normal cell lines) on micropatterns. On the basis of the analysis of experimental data, we found two critical areas about cell proliferation: (1) the critical spreading area of cells from almost no proliferation to confined proliferation, denoted as A_P and (2) the critical spreading area of cells from confined proliferation to almost free proliferation, denoted as A_FP. We further summarized the relative size relationship between these two critical areas and the characteristic areas of cell adhesion on both patterned and nonpatterned surfaces. While proliferation of single primary cells was affected by cell spreading, those cell lines, irrespective of normal and cancer cells, did not exhibit significant cell-spreading effects. As a result, this study reveals that proliferation of single cells is dependent upon spreading area, in particular for primary cells on material surfaces.

The p53 stabilizing agent CP-31398 and multi-kinase inhibitors. Designing, synthesizing and screening of styrylquinazoline series

Quinazoline derivatives constitute a large family of small-molecule inhibitors of tyrosine kinases. In the current study, the p53 protein reactivator CP-31398 was tested against a panel of kinases on the assumption that it was structurally similar to other active inhibitors. Although it was found to be active in the enzyme-based assay, this compound did not block the proliferation of cancer cells at a feasible concentration level. The styrylquinazoline was used to design new structures that might be potential multitarget inhibitors. Subsequently, a series of compounds was obtained and characterized. Their inhibitory activity in a panel of tyrosine kinases had an antiproliferative effect against several cancer cell lines that have different expression levels of those proteins. The mode of protein interaction was tested for the most active compound in docking experiments.

Andrographolide derivative as STAT3 inhibitor that protects acute liver damage in mice

Sustained activation of the Janus kinase-signal transducers and activators of transcription (JAK-STAT) pathway contributed to the progression of cancer and liver diseases. STAT3 signaling inhibitor has been extensively investigated for pharmacological use. We synthesized a series of andrographolide derivatives, and characterized their activity against STAT3 signaling pathway both in vitro and in the CCl₄-induced acute liver damage mice model. Among these derivatives, compound 24 effectively inhibited phosphorylation and dimerization of STAT3 but not its DNA binding activity. Compound 24 significantly ameliorated carbon tetrachloride-induced acute liver damage in vivo without changing mice body weight. Treatment with 24 attenuated hepatic pathologic damage and promoted hepatic proliferation and activation of STAT3. Compound 24 inhibited elevated expression of α-smooth muscle actin and serum pro-inflammatory cytokines downstream of STAT3 but not those factors that are regulated by NF-κB or SMADs. In summary, our results suggest that compound 24 may serve as a potential therapeutic agent for the treatment of hepatic damage or a liver protection agent via regulating STAT3 activation.

Structural Biology of STAT3 and Its Implications for Anticancer Therapies Development

Transcription factors are proteins able to bind DNA and induce the transcription of specific genes. Consequently, they play a pivotal role in multiple cellular pathways and are frequently over-expressed or dysregulated in cancer. Here, we will focus on a specific “signal transducer and activator of transcription” (STAT3) factor that is involved in several pathologies, including cancer. For long time, the mechanism by which STAT3 exerts its cellular functions has been summarized by a three steps process: (1) Protein phosphorylation by specific kinases, (2) dimerization promoted by phosphorylation, (3) activation of gene expression by the phosphorylated dimer. Consequently, most of the inhibitors reported in literature aimed at blocking phosphorylation and dimerization. However, recent observations reopened the debate and the entire functional mechanism has been revisited stimulating the scientific community to pursue new inhibition strategies. In particular, the dimerization of the unphosphorylated species has been experimentally demonstrated and specific roles proposed also for these dimers. Despite difficulties in the expression and purification of the full length STAT3, structural biology investigations allowed the determination of atomistic structures of STAT3 dimers and several protein domains. Starting from this information, computational methods have been used both to improve the understanding of the STAT3 functional mechanism and to design new inhibitors to be used as anticancer drugs. In this review, we will focus on the contribution of structural biology to understand the roles of STAT3, to design new inhibitors and to suggest new strategies of pharmacological intervention.