HS-173, a selective PI3K inhibitor, induces cell death in head and neck squamous cell carcinoma cell lines

Cell-Permeable Fluorescent Sensors Enable Rapid Live Cell Visualization of Plasma Membrane and Nuclear PIP3 Pools

Phosphoinositides, phospholipids that are key cell-signal mediators, are present at very low levels in cellular membranes and within nuclei. Phosphatidylinositol-(3,4,5)-trisphosphate (PIP3), a phosphoinositide barely present in resting cell membranes, is produced when cells receive either growth, proliferation, or movement signals. Aberrant PIP3 levels are associated with the formation of cancers. PIP3 pools are also present in the nucleus, specifically in the nucleolus. However, questions related to the organization and function of this lipid in such membraneless intranuclear structures remain unanswered. Therefore, chemical sensors for tracking cellular PIP3 are invaluable not only for timing signal initiation in membranes but also for identifying the organization and function of membraneless nuclear PIP3 pools. Because PIP3 is present in the inner leaflet of cell membranes and in the nucleus, cell-permeable, rapid-response fluorescent sensors would be ideal. We have designed two peptide-based, water-soluble, cell-permeable, ratiometric PIP3 sensors named as MFR-K17H and DAN-NG-H12G. MFR-K17H rapidly entered into the cell cytoplasm, distinctly reporting rapid (<1 min) time scales of growth factor-stimulated PIP3 generation and depletion within cell membranes in living cells. Importantly, MFR-K17H lighted up inherently high levels of PIP3 in triple-negative breast cancer cell membranes, implying future applications in the detection of enhanced PIP3 levels in cancerous cells. On the other hand, DAN-NG-H12G targeted intranuclear PIP3 pools, revealing that within membraneless structures, PIP3 resided in a hydrophobic environment. Together, both probes form a unique orthogonally targeted combination of cell-permeable, ratiometric probes that, unlike previous cell-impermeable protein-based sensors, are easy to apply and provide an unprecedented handle into PIP3-mediated cellular processes.

Imidazopyridine-based kinase inhibitors as potential anticancer agents: A review

Considering the fundamental role of protein kinases in the mechanism of protein phosphorylation in critical cellular processes, their dysregulation, especially in cancers, has underscored their therapeutic relevance. Imidazopyridines represent versatile scaffolds found in abundant bioactive compounds. Given their structural features, imidazopyridines have possessed pivotal potency to interact with different protein kinases, inspiring researchers to carry out numerous structural variations. In this comprehensive review, we encompass an extensive survey of the design and biological evaluations of imidazopyridine-based small molecules as potential agents targeting diverse kinases for anticancer applications. We describe the structural elements critical to inhibitory potency, elucidating their key structure-activity relationships (SAR) and mode of actions, where available. We classify these compounds into two groups: Serine/threonine and Tyrosine inhibitors. By highlighting the promising role of imidazopyridines in kinase inhibition, we aim to facilitate the design and development of more effective, targeted compounds for cancer treatment.

Design, Synthesis and Biological Evaluation of 6-(Imidazo[1,2-a]pyridin-6-yl)quinazoline Derivatives as Anticancer Agents via PI3Kα Inhibition

Aberrant expression of the phosphatidylinositol 3-kinase (PI3K) signalling pathway is often associated with tumourigenesis, progression and poor prognosis. Hence, PI3K inhibitors have attracted significant interest for the treatment of cancer. In this study, a series of new 6-(imidazo[1,2-a]pyridin-6-yl)quinazoline derivatives were designed, synthesized and characterized by 1H NMR, 13C NMR and HRMS spectra analyses. In the in vitro anticancer assay, most of the synthetic compounds showed submicromolar inhibitory activity against various tumour cell lines, among which 13k is the most potent compound with IC50 values ranging from 0.09 μΜ to 0.43 μΜ against all the tested cell lines. Moreover, 13k induced cell cycle arrest at G2/M phase and cell apoptosis of HCC827 cells by inhibition of PI3Kα with an IC50 value of 1.94 nM. These results suggested that compound 13k might serve as a lead compound for the development of PI3Kα inhibitor.

ABCB1 and ABCG2 Overexpression Mediates Resistance to the Phosphatidylinositol 3-Kinase Inhibitor HS-173 in Cancer Cell Lines

Constitutive activation of the phosphoinositide-3-kinase (PI3K)/Akt signaling pathway is crucial for tumor growth and progression. As such, this pathway has been an enticing target for drug discovery. Although HS-173 is a potent PI3K inhibitor that halts cancer cell proliferation via G2/M cell cycle arrest, the resistance mechanisms to HS-173 have not been investigated. In this study, we investigated the susceptibility of HS-173 to efflux mediated by the multidrug efflux transporters ABCB1 and ABCG2, which are two of the most well-known ATP-binding cassette (ABC) transporters associated with the development of cancer multidrug resistance (MDR). We found that the overexpression of ABCB1 or ABCG2 significantly reduced the efficacy of HS-173 in human cancer cells. Our data show that the intracellular accumulation of HS-173 was substantially reduced by ABCB1 and ABCG2, affecting G2/M arrest and apoptosis induced by HS-173. More importantly, the efficacy of HS-173 in multidrug-resistant cancer cells could be recovered by inhibiting the drug-efflux function of ABCB1 and ABCG2. Taken together, our study has demonstrated that HS-173 is a substrate for both ABCB1 and ABCG2, resulting in decreased intracellular concentration of this drug, which may have implications for its clinical use.

The inhibitors of KDM4 and KDM6 histone lysine demethylases enhance the anti-growth effects of erlotinib and HS-173 in head and neck cancer cells

Novel therapeutics are required to improve treatment outcomes in head and neck squamous cell carcinoma (HNSCC) patients. Histone lysine demethylases (KDM) have emerged recently as new potential drug targets for HNSCC therapy. They might also potentiate the action of the inhibitors of EGFR and PI3K signaling pathways. This study aimed at evaluating the anti-cancer effects of KDM4 (ML324) and KDM6 (GSK-J4) inhibitors and their combinations with EGFR (erlotinib) and PI3K (HS-173) inhibitors in HNSCC cells. The effect of the inhibitors on the viability of CAL27 and FaDu cells was evaluated using resazurin assay. The effect of the chemicals on cell cycle and apoptosis was assessed using propidium iodide and Annexin V staining, respectively. The effect of the compounds on gene expression was determined using qPCR and Western blot. The changes in cell cycle distribution upon treatment with the compounds were small to moderate, with the exception of erlotinib, which induced G1 arrest. However, all the compounds and their combinations induced apoptosis in both cell lines. These effects were associated with changes in the level of expression of CDKN1A, CCND1 and BIRC5. The inhibition of KDM4 and KDM6 using ML324 and GSK-J4, respectively, can be regarded as a novel therapeutic strategy in HNSCC.

Long non‑coding RNA MIR4435‑2HG promotes the progression of head and neck squamous cell carcinoma by regulating the miR‑383‑5p/RBM3 axis

Recent studies have shown that long non-coding RNAs (lncRNAs) are strongly related to the progression of various types of cancer. The lncRNA MIR4435-2 host gene (MIR4435-2HG) has been recently recognized as a tumor-related lncRNA that is upregulated in several tumors. However, its possible functions in head and neck squamous cell carcinoma (HNSCC) remain unclear. In tShe present study, we observed that MIR4435-2HG expression was markedly upregulated in HNSCC tissues based on a Gene Expression Profiling Interactive Analysis dataset. This result was further confirmed in HNSCC tissues and cell lines using quantitative real-time polymerase chain reaction. In addition, the high expression level of MIR4435-2HG was significantly associated with poor disease-free survival and overall survival in all HNSCC cases and was associated with advanced tumor-metastasis-node stage and poor prognosis. In vitro and in vivo assays demonstrated that MIR4435-2HG knockdown suppressed HNSCC cell proliferation and invasion, epithelial-mesenchymal transition (EMT), and tumor growth as determined by Cell Counting Kit-8, Transwell assays and western blotting. Furthermore, MIR4435-2HG affected HNSCC cell proliferation and migration and EMT by modulating the microRNA miR-383-5p to positively regulate the protein expression level of RNA-binding motif protein 3 (RBM3). In conclusion, we provide a detailed analysis of the roles of MIR4435-2HG in HNSCC and identified the MIR4435-2HG/miR-383-5p/RBM3 axis as a potential therapeutic target for HNSCC treatment.