A novel PI3K axis selective molecule exhibits potent tumor inhibition in colorectal carcinogenesis.

Phosphatidylinositol-3-kinase (PI3K) pathway deregulation is responsible for initiation, chemo-resistance, and poor prognosis of colorectal cancer (CRC). Therefore, PI3K pathway inhibition can provide a plausible way of attaining CRC treatment. We report PI3K target specific synthesis and selection of a potent molecule, that is, 2,3-dihydro-2-(naphthalene-1-yl) quinazolin-4(1H)-one (DHNQ) from quinazolinone series based on the structural activity relationship after evaluation in diverse cancers. This molecule inhibited the PI3K enzyme activity and transcriptional as well as translational expression levels in colorectal cancer (CRC) models. This was associated with subsequent decrease in phosphorylation of its downstream effector proteins, that is, p-Akt(Ser-473) and p-mTORC1(Ser-2448) and decreased ERK signaling. Furthermore, DHNQ decreased expression of cyclins that caused G1 arrest and decreased Bcl-2/Bax ratio after mitochondrial membrane potential loss, reactive oxygen species generation, and an increase in cytosolic Ca2+ loads that is responsible for the decreased CRC cell proliferation and survival. These biochemical changes triggered apoptotic cell death with altered autophagic Beclin-1 and LC3ß expression. It seemed that the PI3K-Akt signaling regulated apoptosis and autophagy through different mechanisms but mTORC1 mediated autophagy appeared not to be involved in the cell death induction by DHNQ. The molecule also showed significant anticancer efficacy in in vivo tumor models without any mortality indicating its non-toxic nature with possible clinical significance. Overall, the selective elucidation of DHNQ molecular mechanism will provide the possible strategies for the clinical development in CRC that may respond to this specific, potent and novel P13K inhibitor. © 2016 Wiley Periodicals, Inc.

Design, synthesis and biological evaluation of ß-boswellic acid based HDAC inhibitors as inducers of cancer cell death.

The synthesis and bio-evaluation of naturally occurring boswellic acids (BAs) as an alternate CAP for the design of new HDAC inhibitors is described. All the compounds were screened against a panel of human cancer cell lines to identify leads, which were subsequently examined for their potential to inhibit HDACs. The identified lead compound showed IC50 value of 6µm for HDACs, found to induce G1 cell cycle arrest at significantly low concentration (1µM) and caused significant loss in mitochondrial membrane potential at 5 and 10µM. Furthermore, specific interactions of the lead molecule inside the catalytic domain were also studied through in silico molecular modeling.

PARP cleavage and perturbance in mitochondrial membrane potential by 3-α-propionyloxy-ß-boswellic acid results in cancer cell death and tumor regression in murine models.

BACKGROUND: Apoptotic induction in cancer cells has become a major focus of anticancer therapeutics. In this regard, ß-boswellic acids, naturally occurring pentacyclic triterpenes, have demonstrated antiproliferative and cytotoxic effects against different types of cancers. Surprisingly, not much has been reported regarding the chemical modifications or preparation of structural analogs of the key constituents of ß-boswellic acid. AIM: The anticancer activity of 3-α-propionyloxy-ß-boswellic acid (POBA) was investigated and this article reports for the first time that the triterpenoid ring of the boswellic acid derivative POBA is targeting the PI3K pathway. MATERIALS & METHODS: Induction of apoptosis of the semi-synthetic derivative of ß-boswellic acid-POBA in vitro was analyzed using a battery of human cancer cell lines followed by cell cycle phase distribution, further validated by DNA fragmentation, and was found to cause mitochondrial membrane potential loss with ultrastructural changes, as observed by electron microscopy studies and expression study using PARP cleavage, as well as validated by in vivo anti-tumor activity. RESULTS: The cytotoxicity data revealed the sensitivity of various human cancer cell lines of varied tissue origin to ß-boswellic acid, which robustly induced cell cycle arrest, DNA fragmentation and loss of mitochondrial membrane potential. Morphological studies of the effects of POBA revealed loss of surface projections, chromatin condensation, apoptotic body formation and POBA-mediated PARP cleavage. For in vivo therapeutic experiments, murine tumor models were treated with POBA and the treatment resulted in a significantly higher level of growth inhibition and apoptosis was significantly induced. CONCLUSION: These findings demonstrate that acyl substituents/groups in the main skeleton of ß-boswellic acid have the potential to be potent chemotherapeutic agents.

Interaction of natural products with cell survival and signaling pathways in the biochemical elucidation of drug targets in cancer.

The use of natural products with therapeutic properties is as ancient as human civilization and for a long time mineral, plant and animal products were the main sources of drugs. Worldwide sales of medicinal plants, crude extracts and finished products amounted to US$15 billion in 1999 and it increased to $23 billion in 2002. More interestingly, the influence of natural products upon anticancer drug discovery and design cannot be underestimated. Approximately 60% of all drugs in clinical trials are either a natural product, compounds derived from natural products or contain pharmacophores derived from active natural products. Thus, even today, in the presence of massive numbers of agents from combinatorial libraries, compounds from natural sources are still in the forefront of cancer chemotherapeutics as sources of active drug types, as well as being involved in drug discovery in diseases such as microbial and parasitic infections and the control of cholesterol/lipids, among other functions.

Antioxidant and protective effect of ethyl acetate extract of podophyllum hexandrum rhizome on carbon tetrachloride induced rat liver injury.

The antioxidant and hepatoprotective activities of ethyl acetate extract was carefully investigated by the methods of DPPH radical scavenging activity, Hydroxyl radical scavenging activity, Superoxide radical scavenging activity, Hydrogen peroxide radical scavenging activity and its Reducing power ability. All these in vitro antioxidant activities were concentration dependent which were compared with standard antioxidants such as BHT, α-tocopherol. The hepatoprotective potential of Podophyllum hexandrum extract was also evaluated in male Wistar rats against carbon tetrachloride (CCl(4))-induced liver damage. Pre-treated rats were given ethyl acetate extract at 20, 30 and 50 mg/kg dose prior to CCl(4) administration (1 ml/kg, 1:1 in olive oil). Rats pre-treated with Podophyllum hexandrum extract remarkably prevented the elevation of serum AST, ALT, LDH and liver lipid peroxides in CCl(4)-treated rats. Hepatic glutathione levels were significantly increased by the treatment with the extract in all the experimental groups. The extract at the tested doses also restored the levels of liver homogenate enzymes (glutathione peroxidase, glutathione reductase, superoxide dismutase and glutathione-S- transferase) significantly. This study suggests that ethyl acetate extract of P. hexandrum has a liver protective effect against CCl(4)-induced hepatotoxicity and possess in vitro antioxidant activities.

Carbon tetrachloride induced kidney and lung tissue damages and antioxidant activities of the aqueous rhizome extract of Podophyllum hexandrum.

BACKGROUND: The present study was conducted to evaluate the in vitro and in vivo antioxidant properties of aqueous extract of Podophyllum hexandrum. The antioxidant potential of the plant extract under in vitro situations was evaluated by using two separate methods, inhibition of superoxide radical and hydrogen peroxide radical. Carbon tetrachloride (CCl4) is a well known toxicant and exposure to this chemical is known to induce oxidative stress and causes tissue damage by the formation of free radicals. METHODS: 36 albino rats were divided into six groups of 6 animals each, all animals were allowed food and water ad libitum. Group I (control) was given olive oil, while the rest groups were injected intraperitoneally with a single dose of CCl4 (1 ml/kg) as a 50% (v/v) solution in olive oil. Group II received CCl4 only. Group III animals received vitamin E at a concentration of 50 mg/kg body weight and animals of groups IV, V and VI were given extract of Podophyllum hexandrum at concentration dose of 20, 30 and 50 mg/kg body weight. Antioxidant status in both kidney and lung tissues were estimated by determining the activities of antioxidative enzymes, glutathione reductase (GR), glutathione peroxidase (GPX), glutathione-S-transferase (GST) and superoxide dismutase (SOD); as well as by determining the levels of reduced glutathione (GSH) and thiobarbituric acid reactive substances (TBARS). In addition, superoxide and hydrogen peroxide radical scavenging activity of the extract was also determined. RESULTS: Results showed that the extract possessed strong superoxide and hydrogen peroxide radical scavenging activity comparable to that of known antioxidant butylated hydroxy toluene (BHT). Our results also showed that CCl4 caused a marked increase in TBARS levels whereas GSH, SOD, GR, GPX and GST levels were decreased in kidney and lung tissue homogenates of CCl4 treated rats. Aqueous extract of Podophyllum hexandrum successfully prevented the alterations of these effects in the experimental animals. CONCLUSION: Our study demonstrated that the aqueous extract of Podophyllum hexandrum could protect the kidney and lung tissue against CCl4 induced oxidative stress probably by increasing antioxidant defense activities.

Exploring Derivatives of Quinazoline Alkaloid l-Vasicine as Cap Groups in the Design and Biological Mechanistic Evaluation of Novel Antitumor Histone Deacetylase Inhibitors.

l-Vasicine is a quinazoline alkaloid with an electron dense ring and additional functionalities in its structure. Employing target oriented synthesis (TOS) based on in silico studies, molecules with significant docking scores containing different derivatives of l-vasicine as caps were synthesized. Interestingly, one molecule, i.e., 4a, which contained 3-hyroxypyrrolidine as a cap group and a six carbon long aliphatic chain as a linker was found to inhibit HDACs. 4a showed more specificity toward class I HDAC isoforms. Also 4a was found to be less cytotoxic toward normal cell lines as compared to cancer cell lines. 4a inhibited cancer cell growth and induced cell death by various mechanisms. However, 4a was found to induce cell death independent of ROS generation, and unlike many natural product based HDAC inhibitors, 4a was found to be nontoxic under in vivo conditions. Importantly, we for the first time report the possibility of using a 3-hydroxypyrrolidine cap for the synthesis of HDAC inhibitors with good potency.

Modulation of glycolysis and lipogenesis by novel PI3K selective molecule represses tumor angiogenesis and decreases colorectal cancer growth.

Phosphatidylinositol 3-kinase (PI3K) pathway drives cancer progression through direct regulation of most oncogenic properties. Here, we report that PI3K pathway signaling up-regulates cancer cell proliferation, metastasis and angiogenesis through modulation of cancer metabolism. These oncogenic metabolic processes were disrupted, by a novel PI3K inhibitor, 3-Dihydro-2-(naphthalene-1-yl) quinazolin-4(1H)-one (DHNQ) in colon cancer cells. DHNQ inhibited the Warburg effect and lipid synthesis by reducing gene expression of glycolytic and lipogenesis regulatory enzymes. This downregulation at gene level by DHNQ inhibited metabolic flux to repress proliferation, migration and invasion characteristics of colon cancer. Furthermore, the metabolic attenuation caused repression of in vitro/in vivo angiogenesis providing new insights in PI3K regulated angiogenesis via metabolic alterations. Our results suggest that multifaceted targeting of oncogenic metabolism by their upstream PI3K regulatory signaling may be an effective cancer treatment approach.

Recent development in targeting PI3K-Akt-mTOR signaling for anticancer therapeutic strategies.

Cancer is a diverse class of diseases which differ widely in their cause and biology. The aberrant behavior of cancer reflects up regulation of certain oncogenic signaling pathways that promote proliferation, inhibit apoptosis, and enable the cancer to spread and evoke angiogenesis. Phosphoinositide-3-kinase(PI3K)/Akt/mammalian target of rapamycin (mTOR) pathway controls various biological processes that are important for normal functioning of the cell via cell cycle progression, survival, migration, transcription, translation and metabolism. However, PI3K signaling pathway is dysregulated almost in all cancers which is due to the amplification and genetic mutation of PI3K gene, encoding catalytic and regulatory subunit of PI3K isoforms. The current review focuses on the structural features of various PI3K isoforms including Akt and mTOR and their inhibition using specific small molecule inhibitors in an attempt to achieve an attractive target for cancer prevention and chemotherapy.

Free radical scavenging activity of Elsholtzia densa.

Medicinal plants have been used traditionally to cure a variety of diseases since ancient times. Elsholtzia densa, a rare annual herb of the Kashmir valley, was assessed for its antioxidant efficacy. Antioxidant activity of the crude extracts was evaluated using 1, 1- diphenyl-2-picryl hydrazyl free radical (DPPH), DNA sugar damage, lipid peroxidation, ferric thiocyanate (FTC) and hydrogen peroxide scavenging assays. The maximum percentage decrease of 1,1-diphenyl-2-picryl hydrazyl radical (DPPH) standard solution was recorded for the 50% ethanolic extract (90.48%). The extracts were further evaluated using the thiobarbituric acid reactive substances assay. The methanolic extract showed the highest activity (32.02%) in reducing oxidative damage to DNA. The antioxidant activity of the extracts was also determined using the linoleic acid system and the highest antioxidant activity (49.64%) was found in the 50% ethanolic extract. In the case of the FTC assay, the 50% ethanolic extract showed the highest activity (70.14%) which was comparable to that of α-tocopherol. Moreover, total phenolics concentration was found to be 62.5mg% and 77.5mg% in the cases of absolute ethanolic and 50% ethanolic extracts, respectively. These findings indicate promising antioxidant activity of crude extracts of the plant and the need for further exploration of their effective use in both modern and traditional systems of medicine.

Understanding histone deacetylases in the cancer development and treatment: an epigenetic perspective of cancer chemotherapy.

Cancer is a pathologic condition that involves genetic and epigenetic events culminating in neoplastic transformation. Alteration in epigenetic events that regulate the transcriptional activity of genes associated with various signaling pathways can influence multiple stages of tumorigenesis. In cancer cells, an imbalance often exists between histone acetyl transferase and histone deacetylase (HDAC) activities, and current research focuses actively on seeking competitive HDAC inhibitors (HDACi) for chemotherapeutic intervention. HDACi are proving useful for cancer prevention and therapy by virtue of their ability to reactivate the expression of epigenetically silenced genes, including those involved in differentiation, cell cycle regulation, apoptosis, angiogenesis, invasion, and metastasis. Furthermore, epidemiological studies suggest that different diets such as intake of cruciferous vegetables may lower the risk of different cancers, and there is growing interest in identifying the specific chemoprotective constituents and mechanistic insights of their action. Interestingly, it has been observed that cancer cells are more sensitive than nontransformed cells to apoptotic induction by some HDACi. Although the mechanistic basis for this sensitivity is unclear, yet HDACi have emerged as important epigenetic target for single and combinatorial chemotherapy. HDACi derived from diverse sources such as microbial, dietary, and synthetic increase acetylation level of cells and bring about anti-proliferative and apoptotic effects specific to cancer cells by way of their role in cell cycle regulation and expression of epigenetically silenced genes.