Identification of quinones as HER2 inhibitors for the treatment of trastuzumab resistant breast cancer

Pharmacological Features and Therapeutic Implications of Plumbagin in Cancer and Metabolic Disorders: A Narrative Review

Plumbagin (PLB) is a naphthoquinone extracted from Plumbago indica. In recent times, there has been a growing body of evidence suggesting the potential importance of naphthoquinones, both natural and artificial, in the pharmacological world. Numerous studies have indicated that PLB plays a vital role in combating cancers and other disorders. There is substantial evidence indicating that PLB may have a significant role in the treatment of breast cancer, brain tumours, lung cancer, hepatocellular carcinoma, and other conditions. Moreover, its potent anti-oxidant and anti-inflammatory properties offer promising avenues for the treatment of neurodegenerative and cardiovascular diseases. A number of studies have identified various pathways that may be responsible for the therapeutic efficacy of PLB. These include cell cycle regulation, apoptotic pathways, ROS induction pathways, inflammatory pathways, and signal transduction pathways such as PI3K/AKT/mTOR, STAT3/PLK1/AKT, and others. This review aims to provide a comprehensive analysis of the diverse pharmacological roles of PLB, examining the mechanisms through which it operates and exploring its potential applications in various medical conditions. In addition, we have conducted a review of the various formulations that have been reported in the literature with the objective of enhancing the efficacy of the compound. However, the majority of the reviewed data are based on in vitro and in vivo studies. To gain a comprehensive understanding of the safety and efficacy of PLB in humans and to ascertain its potential integration into therapeutic regimens for cancer and chronic diseases, rigorous clinical trials are essential. Finally, by synthesizing current research and identifying gaps in knowledge, this review seeks to enhance our understanding of PLB and its therapeutic prospects, paving the way for future studies and clinical applications.

Roles and mechanisms of alternative splicing in cancer - implications for care

Removal of introns from messenger RNA precursors (pre-mRNA splicing) is an essential step for the expression of most eukaryotic genes. Alternative splicing enables the regulated generation of multiple mRNA and protein products from a single gene. Cancer cells have general as well as cancer type-specific and subtype-specific alterations in the splicing process that can have prognostic value and contribute to every hallmark of cancer progression, including cancer immune responses. These splicing alterations are often linked to the occurrence of cancer driver mutations in genes encoding either core components or regulators of the splicing machinery. Of therapeutic relevance, the transcriptomic landscape of cancer cells makes them particularly vulnerable to pharmacological inhibition of splicing. Small-molecule splicing modulators are currently in clinical trials and, in addition to splice site-switching antisense oligonucleotides, offer the promise of novel and personalized approaches to cancer treatment.

Identification of New Mono/Dihydroxynaphthoquinone as Lead Agents That Inhibit the Growth of Refractive and Triple-Negative Breast Cancer Cell Lines

Human epidermal growth factor receptor 2 (HER2) is overexpressed in nearly 20-30% of breast cancers and is associated with metastasis resulting in poor patient survival and high recurrence. The dual EGFR/HER2 kinase inhibitor lapatinib has shown promising clinical results, but its limitations have also led to the resistance and activation of tumor survival pathways. Following our previous investigation of quinones as HER2 kinase inhibitors, we synthesized several naphthoquinone derivatives that significantly inhibited breast tumor cells expressing HER2 and trastuzumab-resistant HER2 oncogenic isoform, HER2Δ16. Two of these compounds were shown to be more effective than lapatinib at the inhibition of HER2 autophosphorylation of Y1248. Compounds 7 (5,8-dihydroxy-2-methylnaphthalene-1,4-dione) and 9 (2-(bromomethyl)-5,8-dihydroxynaphthalene-1,4-dione) inhibited HER2-expressing MCF-7 cells (IC50 0.29 and 1.76 μM, respectively) and HER2Δ16-expressing MCF-7 cells (IC50 0.51 and 1.76 μM, respectively). Compound 7 was also shown to promote cell death in multiple refractory breast cancer cell lines with IC50 values ranging from 0.12 to 2.92 μM. These compounds can function as lead compounds for the design of a new series of nonquinonoid structural compounds that can maintain a similar inhibition profile.

Synthetic Method to Form 2,2'-Bis(naphthoquinone) Compounds

We have discovered a transition-metal-free approach to the synthesis of 2,2'-bis(naphthoquinones) using a Diels-Alder reaction of conjugated ketene silyl acetals with benzoquinone. Its monomer analogue can also be synthesized by simply increasing the equivalents of benzoquinone.

SAR and QSAR study on the bioactivities of human epidermal growth factor receptor-2 (HER2) inhibitors

In this paper, structure-activity relationship (SAR, classification) and quantitative structure-activity relationship (QSAR) models have been established to predict the bioactivity of human epidermal growth factor receptor-2 (HER2) inhibitors. For the SAR study, we established six SAR (or classification) models to distinguish highly and weakly active HER2 inhibitors. The dataset contained 868 HER2 inhibitors, which was split into a training set including 580 inhibitors and a test set including 288 inhibitors by a Kohonen's self-organizing map (SOM), or a random method. The SAR models were performed using support vector machine (SVM), random forest (RF) and multilayer perceptron (MLP) methods. Among the six models, SVM models obtained superior results compared with other models. The prediction accuracy of the best model (model 1A) was 90.27% and the Matthews correlation coefficient (MCC) was 0.80 on the test set. For the QSAR study, we chose 286 HER2 inhibitors to establish six quantitative prediction models using MLR, SVM and MLP methods. The correlation coefficient (r) of the best model (model 4B) was 0.92 on the test set. The descriptors analysis showed that HAccN, lone pair electronegativity and π electronegativity were closely related to the bioactivity of HER2 inhibitors.

MicroRNA-7 inhibits multiple oncogenic pathways to suppress HER2Δ16 mediated breast tumorigenesis and reverse trastuzumab resistance

The oncogenic isoform of HER2, HER2Δ16, is expressed with HER2 in nearly 50% of HER2 positive breast tumors where HER2Δ16 drives metastasis and resistance to multiple therapeutic interventions including tamoxifen and trastuzumab. In recent years microRNAs have been shown to influence multiple aspects of tumorigenesis and tumor cell response to therapy. Accordingly, the HER2Δ16 oncogene alters microRNA expression to promote endocrine resistance. With the goal of identifying microRNA suppressors of HER2Δ16 oncogenic activity we investigated the contribution of altered microRNA expression to HER2Δ16 mediated tumorigenesis and trastuzumab resistance. Using a gene array strategy comparing microRNA expression profiles of MCF-7 to MCF-7/HER2Δ16 cells, we found that expression of HER2Δ16 significantly altered expression of 16 microRNAs by 2-fold or more including a 4.8 fold suppression of the miR-7 tumor suppressor. Reestablished expression of miR-7 in the MCF-7/HER2Δ16 cell line caused a G1 cell cycle arrest and reduced both colony formation and cell migration activity to levels of parental MCF-7 cells. Suppression of miR-7 in the MCF-7 cell line resulted in enhanced colony formation activity but not cell migration, indicating that miR-7 suppression is sufficient to drive tumor cell proliferation but not migration. MiR-7 inhibited MCF-7/HER2Δ16 cell migration through a mechanism involving suppression of the miR-7 target gene EGFR. In contrast, miR-7 inhibition of MCF-7/HER2Δ16 cell proliferation involved a pathway where miR-7 expression resulted in the inactivation of Src kinase independent of suppressed EGFR expression. Also independent of EGFR suppression, reestablished miR-7 expression sensitized refractory MCF-7/HER2Δ16 cells to trastuzumab. Our results demonstrate that reestablished miR-7 expression abolishes HER2Δ16 induced cell proliferation and migration while sensitizing HER2Δ16 expressing cells to trastuzumab therapy. We propose that miR-7 regulated pathways, including EGFR and Src kinase, represent targets for the therapeutic intervention of refractory and metastatic HER2Δ16 driven breast cancer.

Small molecule tyrosine kinase inhibitors of ErbB2/HER2/Neu in the treatment of aggressive breast cancer

The human epidermal growth factor receptor 2 (HER2) is a member of the erbB class of tyrosine kinase receptors. These proteins are normally expressed at the surface of healthy cells and play critical roles in the signal transduction cascade in a myriad of biochemical pathways responsible for cell growth and differentiation. However, it is widely known that amplification and subsequent overexpression of the HER2 encoding oncogene results in unregulated cell proliferation in an aggressive form of breast cancer known as HER2-positive breast cancer. Existing therapies such as trastuzumab (Herceptin®) and lapatinib (Tyverb/Tykerb®), a monoclonal antibody inhibitor and a dual EGFR/HER2 kinase inhibitor, respectively, are currently used in the treatment of HER2-positive cancers, although issues with high recurrence and acquired resistance still remain. Small molecule tyrosine kinase inhibitors provide attractive therapeutic targets, as they are able to block cell signaling associated with many of the proposed mechanisms for HER2 resistance. In this regard we aim to present a review on the available HER2 tyrosine kinase inhibitors, as well as those currently in development. The use of tyrosine kinase inhibitors as sequential or combinatorial therapeutic strategies with other HER family inhibitors is also discussed.