Melatonin protected against kidney impairment induced by 5-fluorouracil in mice

The utility of 5-fluorouracil (5-FU) as a successful chemotherapeutic drug for several cancers is limited by the induction of kidney injury and dysfunction due to redox imbalance, inflammation, and apoptosis. Meanwhile, melatonin (MLT) is a potent antioxidant and anti-inflammatory natural compound with a wide safety range. The current study aimed to investigate MLT's protective effect against 5-FU-induced kidney impairment. Male mice were given multiple doses of 5-FU at 25 and 100 mg/kg, as well as MLT at 20 mg/kg. MLT treatment alleviated the toxic effect of 5-FU by normalizing blood urea and creatinine levels and preserving the histological structure, indicating MLT's nephroprotective ability. This is accompanied by body weight maintenance, an increase in survival percentage, and preserved hematological parameters in comparison to the 5-FU-treated mice. MLT's renoprotective effect was explained by improvements in C-reactive protein, IL-6, and caspase-3 in kidney tissue, indicating MLT's anti-inflammatory and antiapoptotic ability. Furthermore, MLT inhibited 5-FU-induced lipid peroxidation by maintaining the activity of superoxide dismutase and catalase, as well as glutathione levels in kidney tissue from mice treated with both doses of 5-FU. The current findings show that MLT has a novel protective effect against 5-FU-induced renal injury and renal impairment.

β-caryophyllene oxide induces apoptosis and inhibits proliferation of A549 lung cancer cells

One of the most common cancers that result in death is lung cancer. There is new hope in the fight against lung cancer thanks to the chemopreventive properties of natural dietary substances like β-caryophyllene oxide (CPO), and research is currently being done to test this theory. CPO, a sesquiterpene isolated from medicinal plant essential oils, inhibits carcinogenesis and has been effective in treating many cancers. This study examined how CPO affected proliferation of human lung cancer A549 cells. CPO was found to have an inhibitory concentration (IC50) of 124.1 g/ml. The proliferative markers Ki67 and PCNA were significantly inhibited after cells were treated with CPO at a concentration of 50 g/ml compared to controls. CPO-treated cells expressed more P21, P53, and DNA strand breaks than controls. This was accompanied by a significant cell cycle arrest in the S and G2/M phases. In treated A549 cells, this was also associated with a significant induction of apoptosis, as shown by the upregulation of the expression of caspases 3, 7, and 9, as well as Bax, and the downregulation of Bcl-2. Furthermore, the redox status of treated A549 cells revealed a marked rise in GSH and GPx activity levels and a decline in 4-HNE levels, indicating low oxidative stress following CPO treatment of A549 cells. In conclusion, cell cycle arrest and apoptosis, which are unrelated to oxidative stress, were the mechanisms by which CPO reduced cancer lung cell growth. This finding might be a potential therapeutic target for the treatment of lung cancer. Hypothetical scheme of CPO anticancer effects (mechanism of signaling) in A549 cells; in vitro. CPO treatment increases expression of p21, p53 and DNA fragmentation. These events cause arrest of cell cycle which was associated with significant induction in apoptosis via increase expression of caspases (-3,-7,-9), and Bax and downregulation of Bcl-2.

Sestrin-3 modulation is essential for therapeutic efficacy of cucurbitacin B in lung cancer cells

Many purified compounds from dietary sources have been investigated for their anticancer activities. The main issue with most agents is their effectiveness at high doses which generally could not be delivered to humans through dietary consumption. Here, we observed that cucurbitacin B, a tetracyclic triterpenoid present in pumpkins, gourds and squashes, exhibits antiproliferative effects on human non-small cell lung cancer (NSCLC) cells at nanomolar concentrations. Treatment with cucurbitacin B (0.2-0.6 μM; 24 h) was found to result in decrease in the viability of EGFR-wild type (A549 and H1792) and EGFR-mutant lung cancer cells (H1650 and H1975) and reduction in cell-colonies but had only minimal effect on normal human bronchial epithelial cells. Treatment with cucurbitacin B also caused inhibition of PI3K/mTOR and signal transducer and activator of transcription (STAT)-3 signaling along with simultaneous activation of AMPKα levels in both EGFR-wild type and EGFR-mutant lung cancer cells. Cucurbitacin B caused specific increase in the protein and mRNA expression of sestrin-3 in EGFR-mutant lung cancer cells, but not in EGFR-wild type cells. Treatment with cucurbitacin B to sestrin-3 siRNA treated EGFR-mutant cells further amplified the decrease in cell-viability and caused more sustained G2-phase cell cycle arrest, suggesting that these effects are mediated partly through sestrin-3. We also found that sestrin-3 has a role in the induction of apoptosis by cucurbitacin B in both EGFR-wild type and EGFR-mutant lung cancer cells. These findings suggest novel mechanism by the modulation of sestrin-3 for the action of cucurbitacin B and suggest that it could be developed as an agent for therapy of NSCLC.

Abstract 4109: Cucurbitacin B: A novel natural agent for the management of non-small cell lung cancer

Lung cancer is the primary cause of cancer death in both men and women in the United States and worldwide. The general prognosis is still very low despite of developments in the treatment due to improved surgical techniques, increased application of combined modality treatments and the use of new drugs. Since the past decade, researchers have been investigating a range of purified compounds from dietary sources as possible anticancer drugs. The main issue with the use of natural products is their effectiveness at high doses which generally could not be delivered to humans through dietary consumption. Here, we observed that cucurbitacin B exhibits antiproliferative effects on human non-small cell lung cancer (NSCLC) cells at very low concentrations. The cucurbitacins are highly diverse and oxygenated tetracyclic triterpenoids isolated from plants of Cucurbitaceae family which are well-known for their bitterness of edible products like pumpkins, gourds and squashes. Cucurbitacin B is one of the most abundant and has been most widely used. In this study, we determined the effect of cucurbitacin B on the inhibition of cell-growth and suppression of phosphatidylinositol 3-kinase (PI3K)/Akt/mammalian target of rapamycin (mTOR) signaling in human NSCLC cells. Treatment of cucurbitacin B (0.2-0.6 μM; 24 h) was found to result in 34-61% and 45-65% decrease in the viability of human NSCLC H1792 and A549 cells respectively, but had only minimal effect on normal human bronchial epithelial cells. The IC50 of cucurbitacin B in these cells ranged from 0.43-0.49 μM. The A549 cell colonies were also reduced by treatment with cucurbitacin B in a dose-dependent manner. It has been well documented that mTOR functions downstream of the PI3K/Akt pathway and is phosphorylated in response to stimuli that activate the PI3K/Akt pathway. Treatment of A549 cells with cucurbitacin B (0.2-0.6 μM; 24 h) caused decrease in the protein expression of PI3K (p85 and p110) and inhibition of the phosphorylation of Akt and mTOR. PI3K/Akt-dependent phosphorylation signals through tuberin, the protein product of tuberous sclerosis complex (TSC)1/TSC2 complex, which leads to activation of mTOR. The mTOR also phosphorylates eukaryotic translation initiation factor 4E-binding protein 1 (4E-BP1) which disassociates from the eukaryotic translation initiation factor (eIF) 4E, allowing activation of protein translation. Treatment of A549 cells with cucurbitacin B also caused inhibition of the phosphorylation of p70S6K1, eIF-4E and 4E-BP1 and downstream targets of mTOR. In cucurbitacin B treated cells, there was also inhibition of the constituents of mTOR signaling complex such as Rictor, Raptor, GβL and PRAS40 and activation of AMP-activated protein kinase (AMPKα) and tuberous sclerosis complex (TSC)2. We suggest that cucurbitacin B could be developed as an agent for the management of lung cancer.

Citation Format: Naghma Khan, Farah Jajeh, Sameh M. Shabana, Hasan Mukhtar. Cucurbitacin B: A novel natural agent for the management of non-small cell lung cancer. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 4109. doi:10.1158/1538-7445.AM2014-4109

Abstract 236: Antiproliferative and proapoptotic effects of (-)-epigallocatechin-3-gallate encapsulated in chitosan nanoparticles on human prostate carcinoma cells

In preclinical animal models (-)-epigallocatechin-3-gallate (EGCG), the major polyphenol of green tea, has shown excellent effects in preventing and/or treating many cancers including prostate cancer (PCa). Chemoprevention is a practical approach for cancer management however its applicability to humans has met with limited success due to several issues including its limited bioavailability. We recently employed the use of nanotechnology to improve the outcome of natural agents for cancer chemoprevention and termed the concept as ‘nanochemoprevention’. To demonstrate the proof-of-principle we encapsulated EGCG in PLA-PEG nanoparticles and showed that this formulation demonstrates greater than ten-fold dose advantage over non-encapsulated EGCG in human PCa PC3 cells both in vitro and in vivo. However, this nanoformulation is not suitable for oral delivery. We recently reported the synthesis, characterization and efficacy assessment of a nanotechnology-based formulation of chitosan encapsulating EGCG (chit-nanoEGCG) for treatment of PCa in a xenograft model. We now show the efficacy of chit-nanoEGCG in LNCaP (androgen responsive) and PC3 (androgen unresponsive) human PCa cells for induction of apoptosis and inhibition of cell growth. The effective dose of EGCG for inhibiting cell growth was reduced significantly when encapsulated in chitosan nanoparticles. The IC50 of chit-nanoEGCG was observed to be 4 μM as compared to 90 μM with native EGCG in PC3 cells. For LNCaP cells the IC50 of chit-nanoEGCG was observed to be 1 μM as compared to 45 μM of native agent. Further, we also observed a significant inhibition in the colony formation potential of these cells when treated with low doses of chit-nanoEGCG (2-4 μM) at which native EGCG had no effect. Our next goal was to determine if EGCG encapsulated in this nanoformulation retains its mechanistic identity. Treatment of LNCaP and PC3 with chit-nanoEGCG (1 and 2 μM) and (4 and 6 μM), respectively, for 48 hrs as compared with native EGCG (40 and 50 μM) and (80 and 100 μM) resulted in significant: i) induction of poly (ADP-ribose) polymerases cleavage (PARP), ii) increase of protein expression of Bax with concomitant decrease in Bcl2 and, iii) activation of cleaved caspases 3,7,8,9. To further confirm the induction of apoptosis, we performed annexin/PI staining and observed significant presence of annexin positive cells in chit-nanoEGCG treated PC3 and LNCaP cells. Further, we also observed that chit-nano EGCG treatment resulted in arrest of the cells in S phase of the cell cycle and cell cycle-regulatory molecules operative in the G1/S phase of the cell cycle were significantly modulated. All these effects were seen at much lower doses in chit-nanoEGCG treated cells as compared to the native agent. Collectively, chit-nanoEGCG could prove useful for preventing and/or treating human PCa.

Citation Format: Sameh M. Shabana, Imtiaz A. Siddiqui, Naghma Khan, Vaqar M. Adhami, Qateeb A. Khan, Shaker A. Mousa, Ahmed E. Hagras, Hasan Mukhtar, Mohamed A. Elmissiry. Antiproliferative and proapoptotic effects of (-)-epigallocatechin-3-gallate encapsulated in chitosan nanoparticles on human prostate carcinoma cells. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 236. doi:10.1158/1538-7445.AM2014-236

Oral administration of naturally occurring chitosan-based nanoformulated green tea polyphenol EGCG effectively inhibits prostate cancer cell growth in a xenograft model

In preclinical animal models, several phytochemicals have shown excellent potential to be used as effective agents in preventing and treating many cancers. However, the limited bioavailability of active agents could be one reason for their restricted usefulness for human consumption. To overcome this limitation, we recently introduced the concept of nanochemoprevention by encapsulating useful bioactive food components for their slow and sustained release. Here, we report the synthesis, characterization and efficacy assessment of a nanotechnology-based oral formulation of chitosan nanoparticles encapsulating epigallocatechin-3-gallate (Chit-nanoEGCG) for the treatment of prostate cancer (PCa) in a preclinical setting. Chit-nanoEGCG with a size of <200nm diameter and encapsulating EGCG as determined by dynamic light scattering and transmission electron microscope showed slow release of EGCG in simulated gastric juice acidic pH and faster release in simulated intestinal fluid. The antitumor efficacy of Chit-nanoEGCG was assessed in subcutaneously implanted 22Rν1 tumor xenografts in athymic nude mice. Treatment with Chit-nanoEGCG resulted in significant inhibition of tumor growth and secreted prostate-specific antigen levels compared with EGCG and control groups. In tumor tissues of mice treated with Chit-nanoEGCG, compared with groups treated with EGCG and controls, there was significant (i) induction of poly (ADP-ribose) polymerases cleavage, (ii) increase in the protein expression of Bax with concomitant decrease in Bcl-2, (iii) activation of caspases and (iv) reduction in Ki-67 and proliferating cell nuclear antigen. Through this study, we propose a novel preventive and therapeutic modality for PCa using EGCG that addresses issues related to bioavailability.

Abstract 3663: Prostate specific membrane antigen (PSMA) targeting nano-EGCG for prostate cancer prevention and treatment

We recently employed the use of nanotechnology to improve the outcome of bioactive food components for cancer chemoprevention and termed the concept as ‘nanochemoprevention’ (Cancer Res. 2009;69(5):1712-6). To demonstrate the proof-of-principle we encapsulated green tea polyphenol epigallocatechin-3-gallate (EGCG) in polylactic acid-polyethylene glycol (PLA-PEG) nanoparticles and showed that this formulation demonstrates greater than ten-fold dose advantage over non-encapsulated EGCG in human prostate cancer (PCa) cells both in vitro and in vivo settings. Emerging data suggest that EGCG possess cancer preventive as well as chemotherapeutic potential against PCa. More recently, we also proposed targeted nanoparticles as novel prototypes for the delivery of EGCG (J Med Chem. 2011;54:1321-32) for prevention and therapy of PCa. Here, we extended the work and developed polymeric EGCG-encapsulated nanoparticles targeted with small molecular entities able to bind to prostate specific membrane antigen (PSMA), a transmembrane protein that is overexpressed on PCa cells, and evaluated their efficacy in several in vitro assays using PCa cell lines of differential PSMA expression status. Biocompatible polymer PLGA-PEG-COOH was synthesized and used as base to conjugate a urea-based inhibitor (DCL) or a glutamate-containing molecule (Asp-Glu) to obtain PLGA-PEG-DCL and PLGA-PEG-Asp-Glu nanoparticles suitable for targeted delivery to the prostate. Next, to investigate the impact of DCL- and Asp-Glu-PEGylation on ligand binding, a comparative docking study on the PSMA active site was performed, and crucial protein-ligand interactions were analyzed. Prepared nanoparticles were characterized in terms of morphology, size and zeta potential, encapsulation efficiency, and in vitro release kinetics. Nanoparticles derived from these three polymer systems were spherical in shape with a unimodal size distribution, showing mean diameter ranging from 130 to 250 nm with a zeta potential of around -30 mV. Cellular binding and uptake of the fluorescent nanosystems were detected in PC-3, DU-145 and LNCaP cell lines at two time points and PSMA specific internalization and accumulation was observed. The antiproliferative efficacy of nano-EGCG, compared to EGCG alone, was assessed 72 h post treatment using MTT assay. Both PSMA specific EGCG polymeric nanoparticles lead to an increased antiproliferative and pro-apoptotic activity in PSMA positive LNCaP cells as compared to PSMA negative DU145 and PC3 cells. These data suggest that encapsulated EGCG retains its biological effectiveness, with prostate specific targeting, for exerting its pro-apoptotic properties, critically important determinant of chemopreventive and chemotherapeutic effects of EGCG.

Citation Format: Imtiaz A. Siddiqui, Vanna Sanna, Vaqar M. Adhami, Sameh M. Shabana, Mario Sechi, Hasan Mukhtar. Prostate specific membrane antigen (PSMA) targeting nano-EGCG for prostate cancer prevention and treatment. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 3663. doi:10.1158/1538-7445.AM2013-3663