Two novel nickel( ii ) complexes [NiL ^I ]·CH ₃ CN ( 1 ·CH ₃ CN) and [Ni(H ₂ L ^II )(NCS) ₂ ]·0.5H ₂ O ( 2 ·0.5H ₂ O) were fabricated and in in vitro experiments they both showed the dose dependent cytotoxicity and killed A549 lung cancer cells via an apoptotic pathway.

The erythroblastosis virus E26 transforming sequences (ETS) family of transcription factors consists of a highly conserved group of genes that play important roles in cellular proliferation, differentiation, migration and invasion. Chromosomal translocations fusing ETS factors to promoters of androgen responsive genes have been found in prostate cancers, including the most clinically aggressive forms. ERG and ETV1 are the most commonly translocated ETS proteins. Over-expression of these proteins in prostate cancer cells results in a more invasive phenotype. Inhibition of ETS activity by small molecule inhibitors may provide a novel method for the treatment of prostate cancer. We recently demonstrated that the small molecule YK-4-279 inhibits biological activity of ETV1 in fusion-positive prostate cancer cells leading to decreased motility and invasion in-vitro. Here, we present data from an in-vivo mouse xenograft model. SCID-beige mice were subcutaneously implanted with fusion-positive LNCaP-luc-M6 and fusion-negative PC-3M-luc-C6 tumors. Animals were treated with YK-4-279, and its effects on primary tumor growth and lung metastasis were evaluated. YK-4-279 treatment resulted in decreased growth of the primary tumor only in LNCaP-luc-M6 cohort. When primary tumors were grown to comparable sizes, YK-4-279 inhibited tumor metastasis to the lungs. Expression of ETV1 target genes MMP7, FKBP10 and GLYATL2 were reduced in YK-4-279 treated animals. ETS fusion-negative PC-3M-luc-C6 xenografts were unresponsive to the compound. Furthermore, YK-4-279 is a chiral molecule that exists as a racemic mixture of R and S enantiomers. We established that (S)-YK-4-279 is the active enantiomer in prostate cancer cells. Our results demonstrate that YK-4-279 is a potent inhibitor of ETV1 and inhibits both the primary tumor growth and metastasis of fusion positive prostate cancer xenografts. Therefore, YK-4-279 or similar compounds may be evaluated as a potential therapeutic tool for treatment of human prostate cancer at different stages.

Ezrin is a scaffolding protein that is involved in oncogenesis by linking cytoskeletal and membrane proteins. Ezrin interacts with epidermal growth factor receptor (EGFR) in the cell membrane, but little is known about the effects of this interaction on EGFR signaling pathway. In this study, we established the biological and functional significance of ezrin-EGFR interaction in non-small cell lung cancer (NSCLC) cells. Endogenous ezrin and EGRF interaction was confirmed by co-immunoprecipitation and immunofluorescent staining. When expression of ezrin was inhibited, EGFR activity and phosphorylation levels of downstream signaling pathway proteins ERK and STAT3 were decreased. Cell fractionation experiments revealed that nuclear EGFR was significantly diminished in ezrin-knockdown cells. Consequently, mRNA levels of EGFR target genes AURKA, COX-2, cyclin D1, and iNOS were decreased in ezrin-depleted cells. A small molecule inhibitor of ezrin, NSC305787, reduced EGF-induced phosphorylation of EGFR and downstream target proteins, EGFR nuclear translocation, and mRNA levels of nuclear EGFR target genes similar to ezrin suppression. NSC305787 showed synergism with erlotinib in wild-type EGFR-expressing NSCLC cells, whereas no synergy was observed in EGFR-null cells. Phosphorylation of ezrin on Y146 was found as an enhancer of ezrin-EGFR interaction and required for increased proliferation, colony formation, and drug resistance to erlotinib. These findings suggest that ezrin-EGFR interaction augments oncogenic functions of EGFR and that targeting ezrin may provide a potential novel approach to overcome erlotinib resistance in NSCLC cells.

Ezrin is a key regulator of cancer metastasis that links the extracellular matrix to the actin cytoskeleton and regulates cell morphology and motility. We discovered a small-molecule inhibitor, NSC305787, that directly binds to ezrin and inhibits its function. In this study, we used a nano-liquid chromatography-tandem mass spectrometry (nano-LC–MS-MS)-based proteomic approach to identify ezrin-interacting proteins that are competed away by NSC305787. A large number of the proteins that interact with ezrin were implicated in protein translation and stress granule dynamics. We validated direct interaction between ezrin and the RNA helicase DDX3, and NSC305787 blocked this interaction. Downregulation or long-term pharmacological inhibition of ezrin led to reduced DDX3 protein levels without changes in DDX3 mRNA. Ectopic overexpression of ezrin in low-ezrin-expressing osteosarcoma cells caused a notable increase in DDX3 protein levels. Ezrin inhibited the RNA helicase activity of DDX3 but increased its ATPase activity. Our data suggest that ezrin controls the translation of mRNAs preferentially with a structured 5′ untranslated region, at least in part, by sustaining the protein level of DDX3 and/or regulating its function. Therefore, our findings suggest a novel function for ezrin in regulation of gene translation that is distinct from its canonical role as a cytoskeletal scaffold at the cell membrane.

Background and Purpose: HIV‐1 transcription is activated by the Tat protein which recruits the cyclin‐dependent kinase CDK9/cyclin T1 to TAR RNA. Tat binds to protein phosphatase‐1 (PP1) through the Q³⁵VCF³⁸ sequence and translocates PP1 to the nucleus. PP1 dephosphorylates CDK9 and activates HIV‐1 transcription. We have synthesized a low MW compound 1H4, that targets PP1 and prevents HIV‐1 Tat interaction with PP1 and inhibits HIV‐1 gene transcription. Here, we report our further work with the 1H4‐derived compounds and analysis of their mechanism of action.Experimental Approach: Using the 1H4‐PP1 complex as a model, we iteratively designed and synthesized follow‐up libraries that were analysed for the inhibition of HIV‐1 transcription and toxicity. We also confirmed the mechanism of action of the PP1‐targeting molecules by determining the affinity of binding of these molecules to PP1, by analysing their effects on PP1 activity, disruption of PP1 binding to Tat and shuttling of PP1 to the nucleus.Key Results: We identified a tetrahydroquinoline derivative, compound 7, which disrupted the interaction of Tat with PP1. We further optimized compound 7 and obtained compound 7c, renamed 1E7‐03, which inhibited HIV‐1 with low IC₅₀ (fivefold lower than the previously reported compound, 1H4), showed no cytotoxicity and displayed a plasma half‐life greater than 8 h in mice. 1E7‐03 bound to PP1 in vitro and prevented shuttling of PP1 into the nucleus.Conclusions and Implications: Our study shows that low MW compounds that functionally mimic the PP1‐binding RVxF peptide can inhibit HIV‐1 transcription by deregulating PP1.