SRC Increases MYC mRNA Expression in Estrogen Receptor-Positive Breast Cancer via mRNA Stabilization and Inhibition of p53 Function

Beyond genetics: driving cancer with the tumour microenvironment behind the wheel

Cancer has long been viewed as a genetic disease of cumulative mutations. This notion is fuelled by studies showing that ageing tissues are often riddled with clones of complex oncogenic backgrounds coexisting in seeming harmony with their normal tissue counterparts. Equally puzzling, however, is how cancer cells harbouring high mutational burden contribute to normal, tumour-free mice when allowed to develop within the confines of healthy embryos. Conversely, recent evidence suggests that adult tissue cells expressing only one or a few oncogenes can, in some contexts, generate tumours exhibiting many of the features of a malignant, invasive cancer. These disparate observations are difficult to reconcile without invoking environmental cues triggering epigenetic changes that can either dampen or drive malignant transformation. In this Review, we focus on how certain oncogenes can launch a two-way dialogue of miscommunication between a stem cell and its environment that can rewire downstream events non-genetically and skew the morphogenetic course of the tissue. We review the cells and molecules of and the physical forces acting in the resulting tumour microenvironments that can profoundly affect the behaviours of transformed cells. Finally, we discuss possible explanations for the remarkable diversity in the relative importance of mutational burden versus tumour microenvironment and its clinical relevance.

Inhibition of PTPRE suppresses tumor progression and improves sorafenib response in hepatocellular carcinoma

Hepatocellular carcinoma (HCC) has a poor prognosis, and the efficacy of current therapeutic strategies is extremely limited in advanced diseases. Our previous study reported that protein tyrosine phosphatase receptor epsilon (PTPRE) is a promoting factor in HCC progression. In this study, our objective was to evaluate the treatment effect of PTPRE inhibitors in different HCC preclinical models. Our results indicated that the PTPRE inhibitory compound 63 (Cpd-63) inhibited tumor cell proliferation, migration, and HCC organoid growth. Mechanism research revealed that Cpd-63 could inhibit the expression of MYC and MYC targets by inhibiting the activation of SRC. Additionally, we found that Cpd-63 could improve the response of sorafenib in HCC cells. In conclusion, we demonstrated that the PTPRE inhibitors represented a potential therapeutic agent for HCC management.

RNA-binding proteins in breast cancer: Biological implications and therapeutic opportunities

RNA-binding proteins (RBPs) refer to a class of proteins that participate in alternative splicing, RNA stability, polyadenylation, localization and translation of RNAs, thus regulating gene expression in post-transcriptional manner. Dysregulation of RNA-RBP interaction contributes to various diseases, including cancer. In breast cancer, disorders in RBP expression and function influence the biological characteristics of tumor cells. Targeting RBPs has fostered the development of innovative therapies for breast cancer. However, the RBP-related mechanisms in breast cancer are not completely clear. In this review, we summarize the regulatory mechanisms of RBPs and their signaling crosstalk in breast cancer. Specifically, we emphasize the potential of certain RBPs as prognostic factors due to their effects on proliferation, invasion, apoptosis, and therapy resistance of breast cancer cells. Most importantly, we present a comprehensive overview of the latest RBP-related therapeutic strategies and novel therapeutic targets that have proven to be useful in the treatment of breast cancer.

Design and synthesis of dual BRD4/Src inhibitors for treatment of triple-negative breast cancer

Triple-negative breast cancer (TNBC) is an extremely aggressive tumor with limited treatment options and effectiveness. Dual-target inhibitors capable of simultaneously suppressing invasion may represent a promising therapeutic approach for TNBC. In this work, we developed a series of dual BRD4/Src inhibitors by connecting JQ1 and dasatinib using various linkers and evaluated their efficacy against TNBC both in vitro and in vivo. Among these compounds, HL403 demonstrated IC50 values of 133 nM for BRD4 inhibition and 4.5 nM for Src inhibition. Most importantly, HL403 not only exhibited potent anti-proliferative capabilities, but also effectively suppressed the invasion of MDA-MB-231 cells in vitro. Finally, the anti-tumor efficacy of HL403 was validated in a mouse MDA-MB-231 xenograft tumor model, achieving a tumor growth inhibition rate (TGI) of 70.7 %, which was superior to the combination of JQ1 and dasatinib (TGI = 54.0 %). Our research provides a promising and feasible new strategy for improving the treatment of TNBC.

m6A readers, writers, erasers, and the m6A epitranscriptome in breast cancer

Epitranscriptomic modification of RNA regulates human development, health, and disease. The true diversity of the transcriptome in breast cancer including chemical modification of transcribed RNA (epitranscriptomics) is not well understood due to limitations of technology and bioinformatic analysis. N-6-methyladenosine (m6A) is the most abundant epitranscriptomic modification of mRNA and regulates splicing, stability, translation, and intracellular localization of transcripts depending on m6A association with reader RNA-binding proteins. m6A methylation is catalyzed by the METTL3 complex and removed by specific m6A demethylase ALKBH5, with the role of FTO as an 'eraser' uncertain. In this review, we provide an overview of epitranscriptomics related to mRNA and focus on m6A in mRNA and its detection. We summarize current knowledge on altered levels of writers, readers, and erasers of m6A and their roles in breast cancer and their association with prognosis. We summarize studies identifying m6A peaks and sites in genes in breast cancer cells.

Intermedin (adrenomedullin 2) promotes breast cancer metastasis via Src/c-Myc-mediated ribosome production and protein translation

PURPOSE

Breast cancer is the most frequently diagnosed cancer and is the leading cause of cancer-associated mortality in women worldwide. Intermedin (IMD, also known as Adrenomedullin 2, ADM2) is an endogenous peptide that belongs to the calcitonin gene-related peptide family and has been reported to play important roles in several types of cancers, including breast cancer. In this study, we sought to investigate how IMD affects the behavior of breast cancer cells, the underlying mechanism of these effects, and whether blockade of IMD has a therapeutic effect against breast cancer.

METHODS

Transcriptome sequencing (RNA-Seq), cell biological experiments, Western blotting, immunoprecipitation, and animal tumor models were used.

RESULTS

IMD expression was significantly increased in breast cancer samples, and the IMD level was positively correlated with lymph node metastasis and Ki67 expression. Cell biological experiments showed that IMD promoted the anchorage-independent growth, migration, and invasive ability of breast cancer cells. Inhibiting IMD activity with an anti-IMD monoclonal antibody blocked these tumor-promoting effects. In addition, blockade of IMD reduced in situ tumor growth and significantly decreased lung metastasis of 4T1 breast cancer in vivo. IMD induced Src kinase phosphorylation, which triggered the transcription of c-Myc, a major oncoprotein controlling the expression of genes that encode ribosomal components. Our data suggest that IMD is involved in breast cancer cell invasion and metastasis, potentially through increasing ribosome biogenesis and protein translation via the Src/c-Myc signaling pathway.

CONCLUSION

These results suggest that IMD may be a novel target for the treatment of breast cancer.

Glioblastoma Stem Cells-Useful Tools in the Battle against Cancer

Glioblastoma stem cells (GSCs) are cells with a self-renewal ability and capacity to initiate tumors upon serial transplantation that have been linked to tumor cell heterogeneity. Most standard treatments fail to completely eradicate GSCs, causing the recurrence of the disease. GSCs could represent one reason for the low efficacy of cancer therapy and for the short relapse time. Nonetheless, experimental data suggest that the presence of therapy-resistant GSCs could explain tumor recurrence. Therefore, to effectively target GSCs, a comprehensive understanding of their biology and the survival and developing mechanisms during treatment is mandatory. This review provides an overview of the molecular features, microenvironment, detection, and targeting strategies of GSCs, an essential information required for an efficient therapy. Despite the outstanding results in oncology, researchers are still developing novel strategies, of which one could be targeting the GSCs present in the hypoxic regions and invasive edge of the glioblastoma.

Sublethal doxorubicin promotes migration and invasion of breast cancer cells: role of Src Family non-receptor tyrosine kinases

BACKGROUND

Doxorubicin (Dox) is a widely used chemotherapy, but its effectiveness is limited by dose-dependent side effects. Although lower Dox doses reduce this risk, studies have reported higher recurrence of local disease with no improvement in survival rate in patients receiving low doses of Dox. To effectively mitigate this, a better understanding of the adverse effects of suboptimal Dox doses is needed.

METHODS

Effects of sublethal dose of Dox on phenotypic changes were assessed with light and confocal microscopy. Migratory and invasive behavior were assessed by wound healing and transwell migration assays. MTT and LDH release assays were used to analyze cell growth and cytotoxicity. Flow cytometry was employed to detect cell surface markers of cancer stem cell population. Expression and activity of matrix metalloproteinases were probed with qRT-PCR and zymogen assay. To identify pathways affected by sublethal dose of Dox, exploratory RNAseq was performed and results were verified by qRT-PCR in multiple cell lines (MCF7, ZR75-1 and U-2OS). Regulation of Src Family kinases (SFK) by key players in DNA damage response was assessed by siRNA knockdown along with western blot and qRT-PCR. Dasatinib and siRNA for Fyn and Yes was employed to inhibit SFKs and verify their role in increased migration and invasion in MCF7 cells treated with sublethal doses of Dox.

RESULTS

The results show that sublethal Dox treatment leads to increased migration and invasion in otherwise non-invasive MCF7 breast cancer cells. Mechanistically, these effects were independent of the epithelial mesenchymal transition, were not due to increased cancer stem cell population, and were not observed with other chemotherapies. Instead, sublethal Dox induces expression of multiple SFK-including Fyn, Yes, and Src-partly in a p53 and ATR-dependent manner. These effects were validated in multiple cell lines. Functionally, inhibiting SFKs with Dasatinib and specific downregulation of Fyn suppressed Dox-induced migration and invasion of MCF7 cells.

CONCLUSIONS

Overall, this study demonstrates that sublethal doses of Dox activate a pro-invasive, pro-migration program in cancer cells. Furthermore, by identifying SFKs as key mediators of these effects, our results define a potential therapeutic strategy to mitigate local invasion through co-treatment with Dasatinib.

SOCS1: phosphorylation, dimerization and tumor suppression

Suppressor of cytokine signaling (SOCS) family members are upregulated following JAK-STAT pathway activation by cytokines. SOCS proteins are recognized inhibitors of cytokine signaling playing roles in cell growth and differentiation. Moreover, SOCS1 and SOCS3 have been shown to be involved in tumor suppression through their ability to interact with p53 leading to the activation of its transcriptional program and showing the implication of SOCS family members in the regulation of apoptosis, ferroptosis and senescence. More recently, we demonstrated that the SRC family of non-receptor tyrosine kinases (SFK) can phosphorylate SOCS1 leading to its homodimerization and inhibiting its interaction with p53. Then, we reactivated the SOCS1-p53 tumor suppressor axis with the SFK inhibitor dasatinib in combination with the p53 activating compound PRIMA. This work suggests new avenues for cancer treatment and leaves open several new questions that deserve to be addressed.

Lusianthridin targeting of lung cancer stem cells via Src-STAT3 suppression

BACKGROUND

Cancer stem cells (CSCs) are well-recognized as a majority cause of treatment failure and can give rise to relapse. The discovery of compounds attenuating CSCs' properties is crucial for enabling advances in novel therapeutics to limit recurrence. CSCs' features in lung cancer are regulated through a reduction in Src-STAT3-c-Myc, which drives cancer progression, drug resistance, and metastasis.

METHODS

The effect of lusianthridin suppresses CSC-like phenotypes was determined by 3D culture and anchorage independent growth. The expression of CSC markers and associated proteins were determined by Western blot analyses. Protein ubiquitination and degradation were assessed using immunoprecipitation.

RESULTS

Herein, we report that lusianthridin, a pure compound from Dendrobium venustum, dramatically suppressed CSCs in lung cancer cells as verified by several CSC phenotype assessments and CSC markers. The CSC phenotypes in lusianthridin-treated cells were suppressed through downregulation of Src-STAT3-c-Myc pathways. Ectopic Src introduced by the transfection augmented CSC phenotypes in lung cancer cells through STAT3 (increased active p-STAT3^Tyr705) and c-Myc signals, while the ShRNA-Src transfection or Src inhibitor dasatinib exhibited opposite results. Treatment of the Src-overexpressing cells with lusianthridin resulted in the reversal of active STAT3 (p-STAT3^Tyr705) and c-Myc as well as the CSC marker CD133. Importantly, we confirmed the CSC-targeted activity of lusianthridin in CSC-rich primary lung cancer cells. The compound dramatically inhibited the formation of tumor spheres of primary lung cancer cells. Finally, we demonstrated that after CSC-attenuation by lusianthridin, the lung cancer cells exhibited significantly higher susceptibility to chemotherapeutic drugs. Such a sensitizing effect caused by pro-survival suppression and pro-apoptotic induction together with the abolishment of stemness indicated by the decrease in CSC markers CD133, ABCG2, and ALDH1A1.

CONCLUSION

These findings revealed a novel pharmacological action and the underlying mechanism of lusianthridin in negatively regulating CSC-like phenotypes and sensitizing resistant cancer cells to cemetery.

Differentially expressed gene profile and relevant pathways of the traditional Chinese medicine cinobufotalin on MCF‑7 breast cancer cells

Cinobufotalin is a chemical compound extracted from the skin of dried bufo toads that may have curative potential for certain malignancies through different mechanisms; however, these mechanisms remain unexplored in breast cancer. The aim of the present study was to investigate the antitumor mechanism of cinobufotalin in breast cancer by using microarray data and in silico analysis. The microarray data set GSE85871, in which cinobufotalin exerted influences on the MCF‑7 breast cancer cells, was acquired from the Gene Expression Omnibus database, and the differentially expressed genes (DEGs) were analyzed. Subsequently, protein interaction analysis was conducted, which clarified the clinical significance of core genes, and Gene Ontology and Kyoto Encyclopedia of Genes and Genomes were used to analyze cinobufotalin‑related pathways. The Connectivity Map (CMAP) database was used to select existing compounds that exhibited curative properties similar to those of cinobufotalin. A total of 1,237 DEGs were identified from breast cancer cells that were treated with cinobufotalin. Two core genes, SRC proto‑oncogene non‑receptor tyrosine kinase and cyclin‑dependent kinase inhibitor 2A, were identified as serving a vital role in the onset and development of breast cancer, and their expression levels were markedly reduced following cinobufotalin treatment as detected by the microarray of GSE85871. It also was revealed that the 'neuroactive ligand‑receptor interaction' and 'calcium signaling' pathways may be crucial for cinobufotalin to perform its functions in breast cancer. Conducting a matching search in CMAP, miconazole and cinobufotalin were indicated to possessed similar molecular mechanisms. In conclusion, cinobufotalin may serve as an effective compound for the treatment of a subtype of breast cancer that is triple positive for the presence of estrogen, progesterone and human epidermal growth factor receptor‑2 receptors, and its mechanism may be related to different pathways. In addition, cinobufotalin is likely to exert its antitumor influences in a similar way as miconazole in MCF‑7 cells.