Novel Ras pathway inhibitor induces apoptosis and growth inhibition of K-ras-mutated cancer cells in vitro and in vivo

Discovery of the 4-aminopiperidine-based compound EM127 for the site-specific covalent inhibition of SMYD3

Recent findings support the hypothesis that inhibition of SMYD3 methyltransferase may be a therapeutic avenue for some of the deadliest cancer types. Herein, active site-selective covalent SMYD3 inhibitors were designed by introducing an appropriate reactive cysteine trap into reversible first-generation SMYD3 inhibitors. The 4-aminopiperidine derivative EM127 (11C) bearing a 2-chloroethanoyl group as reactive warhead showed selectivity for Cys186, located in the substrate/histone binding pocket. Selectivity towards Cys186 was retained even at high inhibitor/enzyme ratio, as shown by mass spectrometry. The mode of interaction with the SMYD3 substrate/histone binding pocket was revealed by crystallographic studies. In enzymatic assays, 11C showed a stronger SMYD3 inhibitory effect compared to the reference inhibitor EPZ031686. Remarkably, 11C attenuated the proliferation of MDA-MB-231 breast cancer cell line at the same low micromolar range of concentrations that reduced SMYD3 mediated ERK signaling in HCT116 colorectal cancer and MDA-MB-231 breast cancer cells. Furthermore, 11C (5 μM) strongly decreased the steady-state mRNA levels of genes important for tumor biology such as cyclin dependent kinase 2, c-MET, N-cadherin and fibronectin 1, all known to be regulated, at least in part, by SMYD3. Thus, 11C is as a first example of second generation SMYD3 inhibitors; this agent represents a covalent and a site specific SMYD3 binder capable of potent and prolonged attenuation of methyltransferase activity.

Synergistic interaction of β-caryophyllene with aromadendrene oxide 2 and phytol induces apoptosis on skin epidermoid cancer cells

BACKGROUND

Pamburus missionis (Wight) Swingle (Rutaceae) is traditionally used in the treatment of swellings, chronic rheumatism, paralysis and puerperal diseases. In a previous study the authors demonstrated apoptotic activity of Pamburus missionis essential oil (EO) on A431 and HaCaT cells. The major components of EO were β-caryophyllene (25.40%), 4(14),11- eudesmadiene (7.17%), aromadendrene oxide 2 (14.01%) (AO-(2) and phytol (6.88%).

PURPOSE OF STUDY

To investigate the role as well as the interactions among EO components inducing apoptosis in A431 and HaCaT cells.

METHODS

Isobolographic analysis and combination index methods were used to detect the type of interactions among the essential oil (EO) components. Cell viability was used to detect cytotoxic activity. Mechanism of cell death was studied using Annexin V-FITC/PI binding assay, cell cycle analysis, measurement of MMP and ROS generation by flow cytometry. Expression of apoptosis associated proteins was investigated by western blot.

RESULTS

Combination of P. missionis EO components: β-caryophyllene/ aromadendrene oxide 2 (β-C/AO-(2)), β-caryophyllene/phytol (β-C/P) and aromadendrene oxide 2 /phytol (AO-(2)/P) inhibited growth and colony formation ability of skin epidermoid A431 and precancerous HaCaT cells. Synergistic interaction was observed between β-C/AO-(2) and β-C/P combination while AO-(2)/P exhibited an additive effect. Combination of components induced chromatin condensation, phosphatidylserine externalisation, increase in sub-G1 DNA content, cell cycle arrest at G0/G1 phase and intracellular ROS accumulation. Inhibition of intracellular ROS by N-acetyl cysteine treatment blocked apoptosis induced by the combinations. The combinations induced apoptosis in A431 and HaCaT cells mediated by loss of mitochondrial membrane potential (ΔΨm), increase in Bax/Bcl-2 ratio, release of cytosolic cytochrome c and activation of caspases (cleaved form of caspase-3, caspase-8, caspase-9) and by PARP cleavage.

CONCLUSION

The present study demonstrates interactions among β-C, AO-(2) and P in the induction of apoptosis on A431 and HaCaT cells. These data suggest the combination of β-caryophyllene with aromadendrene oxide 2 and phytol could be potential therapeutics for the treatment of skin epidermoid cancer and precancerous cells.

Biodegradable nanoparticle-mediated K-ras down regulation for pancreatic cancer gene therapy

Biodegradable nanoparticle-mediated K-ras siRNA delivery has shown inhibition of cell proliferation, migration and invasion in pancreatic cancer cells.

Ribonucleoprotein HNRNPA2B1 interacts with and regulates oncogenic KRAS in pancreatic ductal adenocarcinoma cells

BACKGROUND & AIMS

Development of pancreatic ductal adenocarcinoma (PDAC) involves activation of c-Ki-ras2 Kirsten rat sarcoma oncogene homolog (KRAS) signaling, but little is known about the roles of proteins that regulate the activity of oncogenic KRAS. We investigated the activities of proteins that interact with KRAS in PDAC cells.

METHODS

We used mass spectrometry to demonstrate that heterogeneous nuclear ribonucleoproteins (HNRNP) A2 and B1 (encoded by the gene HNRNPA2B1) interact with KRAS G12V. We used co-immunoprecipitation analyses to study interactions between HNRNPA2B1 and KRAS in KRAS-dependent and KRAS-independent PDAC cell lines. We knocked down HNRNPA2B1 using small hairpin RNAs and measured viability, anchorage-independent proliferation, and growth of xenograft tumors in mice. We studied KRAS phosphorylation using the Phos-tag system.

RESULTS

We found that interactions between HRNPA2B1 and KRAS correlated with KRAS-dependency of some human PDAC cell lines. Knock down of HNRNPA2B1 significantly reduced viability, anchorage-independent proliferation, and formation of xenograft tumors by KRAS-dependent PDAC cells. HNRNPA2B1 knock down also increased apoptosis of KRAS-dependent PDAC cells, inactivated c-akt murine thymoma oncogene homolog 1 signaling via mammalian target of rapamycin, and reduced interaction between KRAS and phosphatidylinositide 3-kinase. Interaction between HNRNPA2B1 and KRAS required KRAS phosphorylation at serine 181.

CONCLUSIONS

In KRAS-dependent PDAC cell lines, HNRNPA2B1 interacts with and regulates the activity of KRAS G12V and G12D. HNRNPA2B1 is required for KRAS activation of c-akt murine thymoma oncogene homolog 1-mammalian target of rapamycin signaling, interaction with phosphatidylinositide 3-kinase, and PDAC cell survival and tumor formation in mice. HNRNPA2B1 might be a target for treatment of pancreatic cancer.

EGFR immunoexpression, RAS immunoexpression and their effects on survival in lung adenocarcinoma cases

BACKGROUND

The impacts of epidermal growth factor receptor (EGFR) immunoexpression and RAS immunoexpression on the survival and prognosis of lung adenocarcinoma patients are debated in the literature.

METHODS

Twenty-six patients, who underwent pulmonary resections between 2002 and 2007 in our clinic, and whose pathologic examinations yielded adenocarcinoma, were included in the study. EGFR and RAS expression levels were examined by immunohistochemical methods. The results were compared with the survival, stage of the disease, nodal involvement, lymphovascular invasion, and pleural invasion. Nonparametric bivariate analyses were used for statistical analyses.

RESULTS

A significant link between EGFR immunoexpression and survival has been identified while RAS immunoexpression and survival have been proven to be irrelevant. Neither EGFR, nor RAS has displayed a significant link with the stage of the disease, nodal involvement, lymphovascular invasion, or pleural invasion.

CONCLUSIONS

Positive EGFR immunoexpression affects survival negatively, while RAS immunoexpression has no effect on survival in lung adenocarcinoma patients.

Triggering Ras signalling by intracellular Francisella tularensis through recruitment of PKCα and βI to the SOS2/GrB2 complex is essential for bacterial proliferation in the cytosol

Intracellular proliferation of Francisella tularensis is essential for manifestation of the fatal disease tularaemia, and is classified as a category A bioterrorism agent. The F. tularensis-containing phagosome (FCP) matures into a late endosome-like phagosome with limited fusion to lysosomes, followed by rapid bacterial escape into the cytosol. The Francisella pathogenicity island (FPI) encodes a type VI-like secretion system, and the FPI-encoded IglC is essential for evasion of lysosomal fusion and phagosomal escape. Many host signalling events are likely to be modulated by F. tularensis to render the cell permissive for intracellular proliferation but they are not fully understood. Here we show that within 15 min of infection, intracellular F. tularensis ssp. novicida triggers IglC-dependent temporal activation of Ras, but attached extracellular bacteria fail to trigger Ras activation, which has never been shown for other intracellular pathogens. Intracellular F. tularensis ssp. novicida triggers activation of Ras through recruitment of PKCα and PKCβI to the SOS2/GrB2 complex. Silencing of SOS2, GrB2 and PKCα and PKCβI by RNAi has no effect on evasion of lysosomal fusion and bacterial escape into the cytosol but renders the cytosol non-permissive for replication of F. tularensis ssp. novicida. Since Ras activation promotes cell survival, we show that silencing of SOS2, GrB2 and PKCα and βI is associated with rapid early activation of caspase-3 within 8 h post infection. However, silencing of SOS2, GrB2 and PKCα and βI does not affect phosphorylation of Akt or Erk, indicating that activation of the PI3K/Akt and the Erk signalling cascade are independent of the F. tularensis-triggered Ras activation. We conclude that intracellular F. tularensis ssp. novicida triggers temporal and early activation of Ras through the SOS2/GrB2/PKCα/PKCβI quaternary complex. Temporal and rapid trigger of Ras signalling by intracellular F. tularensis is essential for intracellular bacterial proliferation within the cytosol, and this is associated with downregulation of early caspase-3 activation.

Novel compounds in the treatment of lung cancer: current and developing therapeutic agents

Lung cancer is the leading cause of cancer-related death in the United States. Though incremental advances have been made in the treatment of this devastating disease during the past decade, new therapies are urgently needed. Traditional cytotoxic agents have been combined with other modalities with improved survival for early-stage patients. Newer cytotoxic agents targeting the same or different mechanisms have been developed at different stages. Optimization of various chemotherapy regimens in different settings is one of the aims of current clinical trials. Some predictive biomarkers (eg, excision repair cross-complementing 1, ERCC1) and histotypes (eg, adenocarcinoma) are found to be associated with resistance/response to some cytotoxic drugs. Another notable advance is the addition of targeted therapy to lung cancer treatment. Targeted agents such as erlotinib and bevacizumab have demonstrated clinical benefits and gained Food and Drug Administration approval for lung cancer. More agents targeting various signaling pathways critical to lung cancer are at different stages of development. Along with the effort of new targeted drug discovery, biomarkers such as epidermal growth factor receptor and anaplastic lymphoma kinase mutations have proven useful for patient selection, and more predictive biomarkers have been actively evaluated in non-small cell lung cancer. The paradigm of lung cancer treatment has shifted towards biomarker-based personalized medicine.

KRAS mutations and sensitivity to anti-EGFR monoclonal antibodies in metastatic colorectal carcinoma: an open issue

BACKGROUND

Cetuximab and panitumumab, mAbs targeting EGFR, are registered for metastatic colorectal carcinoma (mCRC) patients whose tumors express EGFR as determined by immunohistochemistry. However, this method is not predictive of treatment efficacy. KRAS, the human homolog of the Kirsten rat sarcoma-2 virus oncogene, encodes a small G-protein that functions downstream of EGFR-induced signalling.

OBJECTIVE/METHODS

To examine KRAS mutations as predictive factors of response to anti-EGFR mAbs using recently published data.

RESULTS/CONCLUSIONS

Several retrospective studies show that efficacy of these mAbs is confined to patients with wild type KRAS and genotyping of tumors should be considered before treatment. The absence of KRAS mutations does not guarantee an improved likelihood of response to cetuximab and panitumumab. Investigation of other genetic and epigenetic biomarkers will be useful to further refine the responder population. Prospective studies to test the efficacy of combined therapies simultaneously targeting EGFR and the RAS/RAF/MAPK signalling pathways for mCRC are warranted.

A review on molecular topology: applying graph theory to drug discovery and design

Molecular topology is an application of graph theory and statistics in fields like chemistry, biology, and pharmacology, in which the molecular structure matters. Its scope is the topological characterization of molecules by means of numerical invariants, called topological indices, which are the main ingredients of the molecular topological models. These are statistical models that are instrumental in the discovery of new applications of naturally occurring molecules, as well as in the design of synthetic molecules with specific chemical, biological, or pharmacological properties. In this review, we focus on pharmacology, which is a novel field of application of molecular topology. Besides summarizing some recent developments, we also seek to bring closer this interesting biomedical application of mathematics to an interdisciplinary readership.

[6]-Gingerol induces reactive oxygen species regulated mitochondrial cell death pathway in human epidermoid carcinoma A431 cells

Since skin cancer incidence and prevalence is constantly rising up the charts despite all efforts, search for newer, better agents for protection and treatment is required. Ginger (Zingiber officinale Roscoe), a monocotyledonous herb, is widely used as a herbal medicine, given the presence of homologous phenolic ketones, of which [6]-gingerol is the major one. The quantity of [6]-gingerol in the fresh ginger rhizome was found to be 104-965 microg/g in common varieties of ginger available in Indian market. Herein, [6]-gingerol was assessed for its anti-apoptotic effects in human epidermoid carcinoma A431 cells. [6]-Gingerol treatment exhibited considerable cytotoxicity as indicated by growth inhibition of A431 cells mediated via generation of reactive oxygen species (ROS). Increase in ROS led to decrease in mitochondrial membrane potential (MMP) and subsequent induction of apoptosis. Results revealed that perturbations in mitochondrial membrane are associated with deregulation of Bax/Bcl-2 ratio at gene transcriptional level as well as protein level, where treatment with [6]-gingerol leads to up-regulation of Cytochrome-c and Apaf-1 subsequently culminating in triggering of Caspase cascade. These firmly suggest that [6]-gingerol can be effectively used for the treatment of skin cancer.