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Nanogels represent an emerging class of drug delivery systems with enhanced renal clearance and serum half-life. However, synthetic polymeric nanogels are immunogenic and less biodegradable than other systems. Protein nanogels, being non-immunogenic; biodegradable; biocompatible; and mechanically, spatially, and temporally tunable, are gaining widespread attention. Elastin, a natural structural component of connective tissue, has enhanced vascular mobility and is highly biodegradable, biocompatible, temperature and pH sensitive, inert in the bloodstream, able to self-assemble, and able to permeate the blood-brain-barrier. In this study, the development of an Elastin Nanogel (ENG) and its functional capacity as a next generation injectable nano-drug carrier was studied. ENG was prepared via an inverse mini-emulsion technique and was characterized and found to be stable at room temperature and cytocompatible with five different prostate cancer cell lines of varied etiologies. Rhodamine-loaded ENG showed enhanced cellular uptake. Blood smear, hemolysis, CBC, PT/APTT, and C3a complement activation assays showed that ENG is vascular tissue compatible and hence meets the objectives of injectable nanogels. The formulated ENG can be efficiently used as an injectable nano-drug carrier for cancer therapy. Moreover, ENG has the potential to encapsulate hydrophobic drugs for targeted drug delivery.

Breast cancer remains a leading cause of female mortality worldwide. Therefore, novel complementary treatments have been sought. Recently, there has been a growing interest in investigating the possible complementary effects of polyphenolic compounds against various malignancies. In the present study, using MCF-7 and MDA-MB-231 human breast adenocarcinoma cells, the anticancer efficacy of a polyphenolic mixture (PFM) was investigated. PFM is composed of curcumin, resveratrol, epigallocatechin gallate, and quercetin. PFM treatment led to a dose-dependent inhibition of cell proliferation, with IC

Sorafenib (SOR) is a multikinase inhibitor with a mild activity against colorectal cancer cells due to multi-drug resistance mechanisms. Potentiated SOR activity was expected upon combination with some ginger derived compounds due to their interference with intracellular drug metabolism. Studying such combination necessitates the development of a sensitive validated LC-MS/MS method for the determination of intra and extracellular concentration of SOR and its N-oxide metabolite (SNX) in colorectal cancer cells. SOR, SNX and the internal standard (diclofenac sodium) were efficiently separated on Eclipse plus C18 column (3.0 ×150 mm, 5 µm) using isocratic elution with acetonitrile and 0.01 M ammonium formate aqueous solution containing 0.1% formic acid (69:31, v/v). Sample pretreatment using solid phase extraction was optimized and the mean percent recoveries were more than 97.01% for both analytes. Detection was conducted at positive ion multiple reaction monitoring (MRM) mode and the monitored mass transitions were 465.2 → 252.2 for SOR and 481.1 → 286.0 for SNX. The method was linear over the range 0.25 - 200.00 ng/mL (r

Several terpenoids were isolated from Ganoderma colossum with potential chemotherapeutic properties against different solid tumor cells. Herein, we further assessed the potential chemomodulatory effects of colossolactone-G to gemcitabine (GCB) and 5-fluorouracil (5-FU) against colorectal cancer cells. Colossolactone-G induced moderate cell killing effects against both HT-29 and HCT-116 cells, with IC50’s of 90.5 ± 1.7 µM and 22.3 ± 3.9 µM, respectively. Equitoxic combination demonstrated a synergistic effect between colossolactone-G and GCB, or 5-FU with combination indices ranging from 0.22 to 0.67. Both GCB and 5-FU induced moderate cell cycle arrest at G0/G1-phase and S-phase. Despite colossolactone-G’s lack of influence on cell cycle distribution, it significantly potentiated GCB- and 5-FU-induced cell cycle arrest. Similarly, colossolactone-G treatment alone did not induce pronounced apoptosis in both cell lines. However, 5-FU and GCB induced significant apoptosis which was further potentiated via combination with colossolactone-G. Furthermore, colossolactone-G significantly increased autophagic cell death response in both HCT-116 and HT-29 cells and potentiated 5-FU- and GCB-induced autophagic cell death. The influence of colossolactone-G alone or in combination with GCB or 5-FU on the apoptosis and autophagy were confirmed by qPCR analysis for the expression of several key apoptosis and autophagy genes such as, TRAIL, TP53INP1, BNIP3, hp62, ATG5, ATG7, Lamp2A and the golden standard for autophagy (LC3-II). In conclusion, a synergistic effect in terms of anticancer properties was observed when colossolactone-G was combined with 5-FU and GCB, where it influenced both apoptosis and autophagic cell death mechanisms.

The Myrteacae family is known as a rich source of phloroglucinols, a group of secondary metabolites with notable biological activities. Leaves of Psidium cattleianum were extracted with chloroform: methanol 8:2 to target the isolation of phloroglucinol derivatives. Isolated compounds were characterized using different spectroscopic methods: nuclear magnetic resonance (NMR), ultra-violet (UV) and mass spectrometry (MS). Two new phloroglucinols were evaluated for cytotoxicity against a panel of six human cancer cell lines, namely colorectal adenocarcinoma cells (HT-29 and HCT-116), hepatocellular carcinoma cells (HepG-2), laryngeal carcinoma (Hep-2), breast adenocarcinoma cells (MCF7 and MDA-MB231), in addition to normal human melanocytes HFB-4. Additionally, cell cycle analysis and annexin-V/FITC-staining were used to gain insights into the mechanism of action of the isolated compounds. The new phloroglucinol meroterpenoids, designated cattleianal and cattleianone, showed selective antiproliferative action against HT-29 cells with IC50’s of 35.2 and 32.1 μM, respectively. Results obtained using cell cycle analysis and annexin-V/FITC-staining implicated both necrosis and apoptosis pathways in the selective cytotoxicity of cattleianal and cattleianone. Our findings suggest that both compounds are selective antiproliferative agents and support further mechanistic studies for phloroglucinol meroterpenoids as scaffolds for developing new selective chemotherapeutic agents.

Terrein is a bioactive marine secondary metabolite isolated from the fungal strain of Penicillium species SF-7181 and Aspergillus terreus. Previous studies showed that terrein possesses cytotoxic properties attributed to interrupting various molecular pathways, such as nuclear factor kappa B (NF-kB). Gemcitabine (GCB) is an anticancer drug commonly used to treat colorectal cancer; however, it suffers from tumor cell resistance and subsequently treatment failure. In this study, the potential anticancer properties of terrein as well as its chemomodulatory effect on GCB are assessed against various colorectal cancer cell lines (SW620, HT29 and HCT116) under normoxic and hypoxic (pO2 ≤ 1%) conditions. The antiproliferative effects of terrein, GCB and their equitoxic combination were evaluated using sulforhodamine-B assay. In SW620, terrein had IC50’s of 66.89±8.5 µM and 73.4±1.3 µM as single treatment, and the IC50’s of GCB in combination treatment were 0.27± 0.01 µM and 0.24±0.04 µM, under hypoxic and normoxic conditions, respectively. In HT29, terrein had IC50’s of 85.5±4.4 µM and 49.6±11.4 µM, and the IC50’s of GCB in combination treatment were 3.2±0.08 µM and 0.27±0.005 µM, under hypoxic and normoxic conditions, respectively. In HCT116, terrein had IC50’s of 21.6±2.891 µM and 74.76±0.97 µM, and the IC50’s of GCB in combination treatment were 0.23±0.03 µM and 0.23±0.005 µM, under hypoxic and normoxic conditions, respectively. In both SW620 and HCT116, terrein exhibited a preferential antitumor effect in hypoxic conditions; however, the opposite was observed in HT29. Upon further analysis via flow cytometry after annexin-V/FITC and PI staining, GCB and its combination treatment with terrein were found to induce necrosis in all cell lines under investigation. In addition, terrein was found to significantly induce significant S-phase cell arrest compared to GCB treatment alone using DNA content cytometry assay coupled with PI staining. Currently, we are studying the expression of multiple cyclins/CDK’s involved in the different cell cycle phases for further understanding of the detailed mechanism of action. Using flowcytometry assessment after staining with acridine orange, terrein suppressed autophagy compared to control cells as well as GCB treatment. NMR metabolomic analysis revealed that the change in oxygen levels significantly affected extracellular amino acid metabolite profiling such as leucin, which increased significantly due to hypoxia; while tyrosine decreased significantly in response to hypoxic environment. Currently, the gene expression profiling corresponding to these amino acids metabolomic changes are undergoing. Therefore, oxygen concentration plays a vital role in the intratumoral amino acid metabolism in response to terrein, GCB and their combination within colorectal cancer cells. Citation Format: Reham K. Abu Hijjleh, Dalia Y. Al Saeedy, Naglaa S. Ashmawy, Ahmed Gouda, Sameh S. Elhady, Ahmed M. Al-Abd. The potential chemo-modulatory effect of the marine-derived secondary metabolite terrein on the anticancer properties of gemcitabine in colorectal cancer cells [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 1065.

Several semisynthetic analogs of camptothecin (CPT) are used clinically for the treatment of various types of cancers, including colorectal (CRC) cancer, despite their severe, potentially life-threatening toxicities. Studies defined key mutations in the UDP-glycosyltransferase 1 polypeptide A1 (UGT1A1) gene in CRC which play a role in the toxicity and resistance of a broad class of anti-cancer drugs that target DNA topoisomerases. UGT-1A1 is responsible for the glucuronidation and detoxification of the active/toxic metabolite of the topoisomerase I poison, CPT and its analogues, SN-38. Herein, we investigated the potential chemomodulatory effects of a UGT1A1-gene inducer, phenytoin, to the anticancer properties of CPT. The cytotoxic effects of CPT, phenytoin and their combination were evaluated against various colorectal cancer cell lines (SW620, HT29 and HCT116) using sulforhodamine-B assay under normoxic and hypoxic conditions. In HT29, CPT alone and after combination treatment had IC50’s of 0.1235 µM and 0.0269 µM, respectively, under normoxic conditions; and 0.1352 µM and 0.0476 µM, respectively, under hypoxic conditions. In SW620, CPT alone and after combination treatment had IC50’s of 1.9861 µM and 0.0087 µM, respectively, under normoxic conditions; and 1.9549 µM and 0.0024 µM, respectively, under hypoxic conditions. In HCT116, CPT alone and after combination treatment had IC50’s of 0.163 µM and 0.0157 µM, respectively, under normoxic conditions; and 0.1013 µM and 0.0766 µM, respectively, under hypoxic conditions. Flow cytometric analysis after annexin-V/FITC staining showed that the combination treatment significantly induced total apoptosis in all cell lines under investigation. In both HT29 and SW620, the combination treatment significantly suppressed the autophagy compared to CPT treatment alone using acridine orange staining coupled with flowcytometry. Cell cycle analysis using DNA content flowcytometry after PI staining showed significant S-phase arrest in the combination treatment when compared to the control across all cell lines under investigation. This indicates that sub-molecular mechanisms of phenytoin induced chemomodulatory effect to CPT anticancer properties is oxygen tension dependent. Further investigation for the intratumoral metabolism of CPT under hypoxic as well as normoxic conditions and particularly those attributed to UGT-1A1 is currently undergoing. Citation Format: Dalia Al Saeedy, Reham K. Abuhijjleh, Ahmed Gouda, Sherif F. El-Khamisy, Ahmed M. Al-Abd. Modulating the polymorphic UGT1A1 gene to enhance camptothecin anti-colorectal effect [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 1049.

Objectives Breast cancer is one of the most commonly diagnosed cancer among women globally. Shogaol, the active constituent of many spices belonging to the Zingiberaceae family, has received wide attention among other shogaols in terms of its anticancer activity against different neoplasms. To date, its efficacy at the detailed molecular level against breast cancer has not been established. Methods In the current study, we investigated the cytotoxic potential and the underlying molecular details of 6-shogaol against breast adenocarcinomacells (MCF-7), and breast ductal carcinoma cells (T47D). Cytotoxicity assay, cell cycle analysis. Real-time PCR (qPCR), apoptosis and autophagy techniques were used for the determination and molecular investigation of its anticancer properties. Results The current study shows that, Notch signaling downregulation (Hes1 and CyclinD1 genes), caused by 6-shogaol, lead to antiproliferative activity in breast cancer cells. The study further shows that treatment with 6-shogaol induced significant and time dependent cell cycle accumulation in G2/M-phase. 6-Shogaol also induced significant apoptosis in breast cancer cells. Interestingly, 6-shogaol inhibited autophagy in breast cancer cell lines, which might force these cells to undergo apoptosis. Conclusion: 6-Shogaol is a promising candidate to be considered as a treatment of breast cancer.

New phenylaminopyrimidine (PAP) derivatives have been designed and synthesised as potential tyrosine kinase inhibitors for the treatment of cancer. The synthesized compounds share a general structure and vary in the substitution pattern at position-2 of the pyridine ring. Several derivatives have demonstrated potent anticancer activities against HCT-116, HT-29 and LS-174T colorectal cancer cells. Furthermore, a number of hits showed good selectivity to Src-kinase. The cytotoxic mechanisms of these compounds were also investigated by studying their effects on cell-cycle distribution. Among all the compounds examined, compound 8b (with a terminal pyridin-3-yl moiety at the pyridine ring) showed the highest inhibitory selectivity towards src-kinase, which was coupled with cell cycle arrest, and apoptotic and autophagic interference, in colorectal cancer cells. This report introduces a novel category of PAP derivatives with promising kinase inhibitory and anticancer effects against colon cancer.

Osteoporosis is a chronic disease in which the skeleton loses a weighty proportion of its mineralized mass and mechanical pliability. Currently available antiosteoporotic agents suffer adverse effects that include elevated risk of thrombosis and cancer. Phytochemicals may constitute a safer and effective option. In the current work, six flavonoids were obtained from Chrozophora tinctoria and identified as amentoflavone (1), apigenin-7-O-β-D-glucopyranoside (2), apigenin-7-O-6′′-E-p-coumaroyl-β-d-glucopyranoside (3), acacetin-7-O-β-d-[α-l-rhamnosyl(1→6)]3′′-E-p-coumaroyl glucopyranoside (4), apigenin-7-O-(6′′-Z-p-coumaroyl)-β-d-glucopyranoside (5), and rutin (6). An extensive review of the literature as well as NMR and mass spectral techniques was employed in order to elucidate the compound structures. Proliferation was enhanced in MCF7, MG-63, and SAOS-2 cells after exposure to subcytotoxic levels of the tested flavonoids. Rutin was chosen for subsequent studies in SAOS-2 cells. Rutin was not found to cause any alteration in the index of proliferation of these cells, when examining the cell cycle distribution by DNA flowcytometric analysis. Rutin was, however, found to increase osteocyte and osteoblast-related gene expression and lower the expression of RUNX suppressor and osteoclast genes. When examining the influence of rutin on vitamin D levels and the activity of alkaline phosphatase enzyme, it was found to enhance both, while decreasing acid phosphatase which is a marker of osteoporosis. Thus, rutin enhances proliferation and ossification markers in bone cells.

Different species belonging to the genus Nephthea (Acyonaceae) are a rich resource for bioactive secondary metabolites. The literature reveals that the gastroprotective effects of marine secondary metabolites have not been comprehensively studied in vivo. Hence, the present investigation aimed to examine and determine the anti-ulcer activity of 4α,24-dimethyl-5α-cholest-8β,18-dihydroxy,22E-en-3β-ol (ST-1) isolated from samples of a Nephthea species. This in vivo study was supported by in silico molecular docking and protein–protein interaction techniques. Oral administration of ST-1 reduced rat stomach ulcers with a concurrent increase in gastric mucosa. Molecular docking calculations against the H+/K+-ATPase transporter showed a higher binding affinity of ST-1, with a docking score value of −9.9 kcal/mol and a pKi value of 59.7 nM, compared to ranitidine (a commercial proton pump inhibitor, which gave values of −6.2 kcal/mol and 27.9 µM, respectively). The combined PEA-reactome analysis results revealed promising evidence of ST-1 potency as an anti-ulcer compound through significant modulation of the gene set controlling the PI3K signaling pathway, which subsequently plays a crucial role in signaling regarding epithelialization and tissue regeneration, tissue repairing and tissue remodeling. These results indicate a probable protective role for ST-1 against ethanol-induced gastric ulcers.

Cisplatin (CDDP) is potent anticancer agent used for several tumor types. Thymoquinone (TQ) is naturally occurring compound drawing great attention as anticancer and chemomodulator for chemotherapies. Herein, we studied the potential cytotoxicity of thymoquinone, CDDP and their combination against human oral squamous cell carcinoma cell in contrast to normal oral epithelial cells. CDDP similarly killed both head and neck squamous cell carcinoma cells (UMSCC-14C) and normal oral epithelial cells (OEC). TQ alone exerted considerable cytotoxicity against UMSCC-14C cells; while it induced weaker killing effect against normal oral epithelial cells (OEC). Equitoxic combination of TQ and CDDP showed additive to synergistic interaction against both UMSCC-14C and OEC cells. TQ alone increased apoptotic cell fraction in UMSCC-14C cells, as early as after 6 hours. In addition, prolonged exposure of UMSCC-14C to TQ alone resulted in 96.7 ± 1.6% total apoptosis which was increased after combination with CDDP to 99.3 ± 1.2% in UMSCC-14C cells. On the other hand, TQ induced marginal increase in the apoptosis in OEC and even decreased the apoptosis induced by CDDP alone. Finally, apoptosis induction results were confirmed by the change in the expression levels of p53, Bcl-2 and Caspase-9 proteins in both UMSCC-14c and OEC cells.

Thymoquinone (TQ) has shown substantial evidence for its anticancer effects. Using human breast cancer cells, we evaluated the chemomodulatory effect of TQ on paclitaxel (PTX). TQ showed weak cytotoxic properties against MCF-7 and T47D breast cancer cells with IC50 values of 64.93 &plusmn, 14 &micro, M and 165 &plusmn, 2 &micro, M, respectively. Combining TQ with PTX showed apparent antagonism, increasing the IC50 values of PTX from 0.2 &plusmn, 0.07 &micro, M to 0.7 &plusmn, 0.01 &micro, M and from 0.1 &plusmn, M to 0.15 &plusmn, 0.02 &micro, M in MCF-7 and T47D cells, respectively. Combination index analysis showed antagonism in both cell lines with CI values of 4.6 and 1.6, respectively. However, resistance fractions to PTX within MCF-7 and T47D cells (42.3 &plusmn, 1.4% and 41.9 &plusmn, 1.1%, respectively) were completely depleted by combination with TQ. TQ minimally affected the cell cycle, with moderate accumulation of cells in the S-phase. However, a significant increase in Pre-G phase cells was observed due to PTX alone and PTX combination with TQ. To dissect this increase in the Pre-G phase, apoptosis, necrosis, and autophagy were assessed by flowcytometry. TQ significantly increased the percent of apoptotic/necrotic cell death in T47D cells after combination with paclitaxel. On the other hand, TQ significantly induced autophagy in MCF-7 cells. Furthermore, TQ was found to significantly decrease breast cancer-associated stem cell clone (CD44+/CD24-cell) in both MCF-7 and T47D cells. This was mirrored by the downregulation of TWIST-1 gene and overexpression of SNAIL-1 and SNAIL-2 genes. TQ therefore possesses potential chemomodulatory effects to PTX when studied in breast cancer cells via enhancing PTX induced cell death including autophagy. In addition, TQ depletes breast cancer-associated stem cells and sensitizes breast cancer cells to PTX killing effects.

By 2030, the mortality rates of colon cancer are expected to increase by 60%. Therapy resistance (resistance to chemo- and targeted therapies) is the main reason for colorectal cancer-related mortality. Despite the development of novel and targeted therapies, chemo-resistance results in a high incidence of metastasis and recurrence. Chemo-sensitization using phytochemicals (natural products), with their multitarget potential and relatively low toxicity, is a recent and innovative strategy proposed to overcome chemo-resistance. They mainly aim to increase the cytotoxic potential of anticancer drugs, limiting their toxic side effects and delaying the appearance of acquired chemo-resistance. Yet, complex mechanisms of chemo-resistance exist that usually enable colorectal cancer cells to escape from the killing effects of the chemotherapeutic agent. Besides, chemo-resistance is a sum of complex phenomena involving many signaling cascades acting collectively for the sake of colorectal cancer cells’ survival. Herein, we summarized the details of several major resistant pathways utilized by CRC cells such as the autophagy, m-TOR pathway, tumor hypoxia, nuclear factor-κB (NF-κB), death receptors (TRAIL-receptors), survivin, and the ubiquitin-proteasome system. In addition, we shed the light on how some potentially promising phytochemicals (natural products) from plants and marine organisms can interfere with these CRC pro-survival resistant pathways.

In contrast to plasma pharmacokinetics, intratumoral pharmacokinetics of doxorubicin (DOX) determines its spatial anti-tumoral activity. Three-dimensional multicellular layers (MCL) model for solid tumors present optimum experimental platform for studying the intratumoral pharmacokinetics of DOX. This might imply new insights for understanding intratumoral pharmacokinetic parameters with realistic clinical implications. Herein, we are presenting simplified method for the spatial in-situ concentration assessment of DOX within the avascular simulating MCL solid tumor model of DLD-1 and HT-29 cell lines. DLD-1 and HT-29 formed viable well-structured MCL model abundant in extracellular matrix component (fibronectin). DOX (100 µM) showed stronger anti-proliferative effect against MCL of DLD-1 compared to HT-29 MCL (38.8% and 27.9%, respectively). The differential potencies of DOX closely correlate to the intratumoral pharmacokinetics within MCL’s of both cell lines. DOX penetrated faster and washed out slower through the MCL of DLD-1 compared to HT-29 MCL. Distribution of DOX within MCL of DLD-1 was more homogenous compared to HT-29 MCL. Tissue concentration of DOX within MCL of DLD-1 was significantly higher than HT-29 MCL’s after 96 h exposure (0.7 and 0.4 µmole/gm tissue, respectively). Concentration of DOX within MCL of both cell lines exceeded the IC50 under monolayer conditions (2.3 ± 0.6 µM and 0.6 ± 0.1 µM, respectively). In addition, DOX was extensively metabolized to less active metabolites (doxorubicinol and doxorubicinone) through the thickness of both MCL’s. In conclusion, Intratumoral pharmacokinetic barriers to DOX might be key determinant in drug resistance on the tissue level, despite cellular and molecular events.

Hepatocellular carcinoma (HCC) is progressively increasing tumor with lack of accurate prognosis and inadequate systemic treatment approaches. Solanum sp. (such as Solanum melongena) is a folk herb which is reported to possess anticancer properties. In a continuity for our interest in pursuing the anticancer activity of compounds isolated from the fruit peels of Solanum melongena, the HPLC profiling and ESI-MS assessment for the methanolic extract evidenced the presence of bioactive glycoalkaloids (solasonine, solasodine and solamargine). These glycoalkaloids were isolated, purified and proved to possess in vitro cytotoxicity against human liver cancer cell lines (Huh7 and HepG2). Herein, we investigated the potential mechanism of action of these compounds using DNA content flow-cytometry and apoptosis/necrosis differential anaylsis using annexin-V/FITC staining. Solasonine, solasodine and solamargine inducd significant antiproliferative effect against liver cancer cells (Huh7 and HepG2) which was attributed to cell cycle arrest at S-phase. Solamargine, solasodine and solasonine induced significant apoptosis in Huh7 cells. Only solamargine-induced cell cycle arrest, was reflected as apoptotic cell killing effect against HepG2 cells. In conclusion, glycoalkaloids derived from Solanum melongena and particularly, solamargine are promising antiproliferative agents with potential anticancer effects.

Breast cancer is one of the most common female cancers and contributes 25.4% of the total diagnosed malignancies in women in 2018. Shogaol, paradol, and gingerol are obtained from many plants belonging to the family Zingiberaceae such as dried ginger and grain of paradise and shows different pharmacological activities. The current study evaluated the anticancer potential of these compounds in combination with chemotherapeutic platinum drugs against breast cancer cells. Cytotoxicity assay, apoptosis assay, immunofluorescent staining cell surface marker analysis, and wound healing assay were used for evaluating the cytotoxic potential of these compounds alone and in combination with platinum chemotherapeutics agents against naïve and resistant breast cancer cell lines (MDA-MB-231 and MCF-7adr, respectively). Platinum drugs showed synergism in combination with shogaol and gingerol against the resistant breast cancer cells (MCF-7adr) with a Combination Index (CI) values of 0.39 and 0.54, respectively. A significant increase was observed in the percentages of early and late apoptotic cells for MDA-MB-231 cells treated with 6-shogaol for 24h. Significant decrease in CD44+/CD24- subpopulation was recorded in both cell lines using flowcytometric analysis. In the Wound healing assay, cells treated with the test compounds migrated significantly slower than control and needed a longer time to heal the scratch. In conclusion, gingerol, shogaol, and paradol compounds showed synergistic cytotoxicity with platinum-based drug and augmented their migration inhibitory activity, apoptotic effects, and tumor-associated stem cell suppressive the potential within naïve and resistant breast cancer cells. Citation Format: Aziza S. Bawadood, Fahad A. Al-Abbasi, Ali M. El-Halawany, Ahmed M. Al-Abd. Synergistic interaction between gingerol, shogaol and paradol with platinum-based chemotherapeutic drugs against naïve and resistant breast cancer cells [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 313.

Prooxidant augmented therapy is a ROS-based anticancer drug in which a prooxidant compound is linked with an inhibitor of antioxidant enzyme(s). This will lead to an auto-synergistic effect with a consequent intracellular accumulation of ROS. In the current study, 15 new imidazole derivatives (4a-o) were synthesized and assessed as unimolecular auto-augmented prooxidant anticancer agents. The compounds were designed based on incorporating α, β-unsaturated ketones (trans-cinnamaldehyde scaffold) as a thioredoxin reductase enzyme inhibitor, and a prooxidant side chain (R) to the core imidazole scaffold of the recently reported cytotoxic lead compound 2-(5-bromothiophen-2-yl)-4,5-diphenyl-1H-imidazole. The antiproliferative/cytotoxic activity of compounds (4a-o) was assessed against breast adenocarcinoma (MCF-7), hepatocellular carcinoma (HepG2), and colorectal adenocarcinoma (HCT-116) cells using SRB-U assay; IC50's and resistance fractions (R-values) were calculated using Emax mathematical model. HepG2 cells were the most sensitive among other tested tumour cell lines; Compounds 4a, 4c, 4e, 4g, 4i, and 4k showed moderate to high HepG2 cytotoxic/antiproliferative activity with average IC50 of 2.2 µM and the resistant fraction (R-values) did not exceed 30%. In addition, compounds 4a, 4c, 4e, 4g, 4i and 4k significantly increased the total and the intracellular ROS levels within 2 hours of exposure up to 158.2% and 117.7% of normal untreated cells, respectively. The potential apoptotic/necrotic effects of compounds 4a, 4c, 4e, 4g, 4i, and 4k against HepG2 cells were investigated after staining with Annexin V-FITC/PI coupled with flow cytometry. Compound 4e showed the most prominent cell-killing effect by inducing 4 folds apoptosis and 2.5 folds necrosis in HepG2 cells compared to untreated cells. Compounds 4g and 4a showed weaker apoptotic and necrotic effects compared to compound 4e. Furthermore, molecular docking was conducted to assess the interaction between the α, β-unsaturated ketones moiety and x-ray crystal structure of thioredoxin reductase enzyme (pdb: 2J3N) using discovery studio 2.5 Cdocker protocol. Compounds 4a, 4c, 4e and 4 g had a proper 3D arrangement that enables them to fit in FAD-binding the site and perform hydrogen bond with THR 58. In addition, In silico investigation of human intestinal absorption after oral administration for Compounds 4a, 4c, 4e, and 4 g was carried out using Accelrys Discovery studio and revealed possible oral absorption to be confirmed experimentally. In conclusion, the auto-augmented compounds possessing prooxidant ROS generator group and α, β-unsaturated ketones not only elicited tumor cell killing effect via increasing the intracellular ROS level but also showed docking study-based evidence for inhibiting the thioredoxin antioxidant enzyme. Citation Format: Abdel-Sattar M. Omar, Eman M El-labbad, Ahmed M. Al-Abd. Design and synthesis of imidazole derivatives as augmented prooxidant anticancer agents [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 287.

The merging of high-throughput gene expression techniques, such as microarray, in the screening of natural products as anticancer agents, is considered the optimal solution for gaining a better understanding of the intervention mechanism. Red yeast rice (RYR), a Chinese dietary product, contains a mixture of hypocholesterolemia agents such as statins. Typically, statins have this effect via the inhibition of HMG‑CoA reductase, the key enzyme in the biosynthesis of cholesterol. Recently, statins have been shown to exhibit various beneficial antineoplastic properties through the disruption of tumor angiogenesis and metastatic processes. Mevinolin (MVN) is a member of statins and is abundantly present in RYR. Early experimental trials suggested that the mixed apoptotic/necrotic cell death pathway is activated in response to MVN exposure. In the current study, the cytotoxic profile of MVN was evaluated against MCF‑7, a breast cancer‑derived cell line. The obtained results indicated that MVN‑induced cytotoxicity is multi‑factorial involving several regulatory pathways in the cytotoxic effects of MVN on breast cancer cell lines. In addition, MVN‑induced transcript abundance profiles inferred from microarrays showed significant changes in some key cell processes. The changes were predicted to induce cell cycle arrest and reactive oxygen species generation but inhibit DNA repair and cell proliferation. This MVN‑mediated multi‑factorial stress triggered specific programmed cell death (apoptosis) and DNA degradation responses in breast cancer cells. Taken together, the observed MVN‑induced effects underscore the potential of this ubiquitous natural compound as a selective anticancer activity, with broad safety margins and low cost compared to benchmarked traditional synthetic chemotherapeutic agents. Additionally, the data support further pre‑clinical and clinical evaluations of MVN as a novel strategy to combat breast cancer and overcome drug resistance.

Tafuramycin-A (TAF) is naturally occurring duocarmycin-SA derivative with known DNA alkylating and/or intercalating potential. On the other hand, TAF possesses excessive and non-specific toxic properties. Epicatechin (EPI) and thymoquinone (TQ) are naturally occurring compounds with a wide range of biological activities, such as anticancer and chemomodulatory potentials. Herein, we temporally assessed the anti-breast cancer properties of TAF alone and in combination with EPI or TQ against naïve (MCF-7, MDA-MB-231 and T47D cells) and resistant breast cancer cells (MCF-7Adr). TAF alone showed very potent cell-killing properties against both naïve and resistant breast cancer cell lines in a time-dependent manner with IC50's ranging from 17 - 190 nM, 2 - 19 nM and 1 - 2 nM after 24 h, 48 h, and 72 h exposures, respectively. To a lesser extent, TQ alone showed moderate cytotoxic properties against all cell lines in a time-dependent manner with IC50's ranging from 4.4 - 18.9 µM, 2.8 - 16.5 µM and 2.1 - 22.7 µM after 24 h, 48 h, and 72 h exposures, respectively. EPI was the weakest in comparison to the previous two agents with IC50's above 100 µM in all cell lines in all durations of exposure. Except 24 h exposure of MDA-MB-231 cells, equitoxic combinations of TAF with TQ showed antagonistic interaction in all cells under investigation with combination indices ranging from 2 - 9.3, 1.3 - 3.7, 1.4 - 3.2 and 0.6 - 3.7 in MCF-7, MCF-7Adr, T47D, and MDA-MB-231 cells, respectively. Combination of TAF with 10 µM EPI did not induce any prominent enhancement in TAF cytotoxic properties. Cell cycle analysis using DNA content flow cytometry showed moderate S-phase and G2/M-phase partial arrest in response to treatment with TAF, TQ and their combinations. While treatment with EPI induced significant arrest in G0/G1-phase which is similar to its reported antiproliferative activity. Further analysis for the differential apoptosis/necrosis cell death using annexin-V/FITC with PI counterstain and coupled with flow cytometric analysis showed significant necrosis induction of TAF alone against breast cancer cells under investigation. Yet, a combination of TAF with TQ or EPI decreased the percentage of necrosis induced by TAF alone; however, it induced significant apoptosis cell death. Yet, the explanation for shifting breast cancer cell death from necrosis to apoptosis due to a combination of TAF with TQ or EPI is currently under molecular investigation and might constitute a high potential in utilizing TAF for the treatment of breast cancer. Citation Format: Ohoud Y. Alshehri, Hanan A. Henidi, Fahad A. Alabbasi, Ibrahim M. El-Deeb, Majed A. Halwani, Ahmed M. Al-Abd. Thymoquinone and epicatechin ameliorate the anticancer properties of tafuramycin-A against naïve and resistant breast cancer cells [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 6558.

Glycogen synthase kinase-3β (GSK-3β) is a serine/threonine kinase with a crucial role in several key cellular functions including tumor cell proliferation and survival. Yet, GSK-3β has emerged as an attractive target for the development of anti-cancer agents. Several small-molecule have been developed as GSK-3β inhibitors. Amongst, several pyrazolopyrimidines based ATP-competitive inhibitors were identified as promising GSK-3β inhibitors. In this work, several pyrazolo[3,4-d]pyrimidine derivatives were designed, synthesized and assessed for their potential anticancer activity. The new compounds are categorized under two templates, Template A and Template B. In these templates two different linkers with varying lengths and electronic properties were used to link additional aromatic ring systems to the core pyrazolopyrimidine scaffold. The aromatic ring systems were designed with different electronic and bonding properties to test their GSK-3β inhibitory activity and consequently their anticancer properties. All compounds under investigation showed GSK-3β inhibitory properties with IC50's ranging from 0.17- 1.01 µM compared to Tideglusib (standard GSK-3β inhibitor) which showed IC50 of 0.22 µM. Furthermore, the compounds were tested for their potential cytotoxicity against two breast cancer cells (MCF-7 and MDA-MB-231) and lung cancer cells (A549). Only one compound from Template B which possesses the longer hydrazide linker and 2,3-dihydroxy phenyl aromatic ring (compound 27), showed considerable cytotoxic effects against MCF-7, MDA-MB-231 and A549 cells (IC50's of 2.4, 2.4 and 2.3 µM, respectively). Compounds 21, 24, 25 and 26 showed weaker cytotoxic effects against cell lines under investigation (IC50's ranged from 29 to 93 µM). DNA content flow-cytometry analysis was undertaken to evaluate the potential effects of compound 27 on the cell cycle distribution of cell lines under investigation. Compound 27 induced significant antiproliferative effect and accumulation of cells in G0/G1-phase after 24 h of exposure. Longer exposure (48 h) to compound 27 resulted in cell cycle arrest in G2/M-phase. Additional assessment for programmed/non-programed cell death using annexin-V/FITC and acridine orange staining coupled with flow-cytometric analysis showed the ability of compound 27 to induce apoptosis as well as autophagy in all cells under investigation. In conclusion, compound 27 represents a promising GSK-3β inhibitor with potential anticancer properties via the induction of cell cycle arrest with subsequent cellular stress and induction of apoptosis and autophagy. Citation Format: Ahmed T. Negmeldin, Mohammed K. AbdElhameid, Dalia Y. Alsaeedy, Fatiha Hammed, Rasha M. Allam, Walid El-Sayed, Ahmed M. Al-Abd. Design, synthesis, and assessment of anticancer properties of pyrazolopyrimidine derivatives as Glycogen Synthase Kinase-3β inhibitors [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr LB-236.

Cinnamaldehyde and curcumin scaffolds are known for their anticancer potential via reactive oxygen species (ROS) generation and cellular damage. Herein, we synthesized a set of heterocyclic compounds build on the naturally-occurring trans-cinnamaldehyde and curcumin scaffolds and assessed their antiproliferative/cytotoxic properties against hepatocellular carcinoma (HepG2), breast adenocarcinoma (MCF-7) and colorectal cancer cells (HCT-116). The general structure of the synthesized compounds comprised 2-(4-fluorophenyl)-4-imidazolone nucleus attached to a 2-phenylpropylidene moiety. The imidazolone's N1 diversity point was attached to a variety of groups that are different in steric as well as electronic properties. Compounds FC01, FC09, FC11, FC12, FC14, FC30 and FC37 (groups attached to N1 diversity point are phenyl, methyl, 4-methylpiperazinyl, n-propyl, 4-hydroxyphenyl, 2-furylmethyl, and 4-methoxyphenyl, respectively) showed considerable cytotoxicity with IC50 ranging from 0.1 to 11.9 µM against MCF-7, HepG2, and HCT-116 cells. Within one hour of exposure to the IC50's of compounds FC09, FC12 and FC31, total ROS was significantly increased to 143.3±1.2%, 158.2±8.6% and 138±9.3% of control. After 2 hours of exposure, compounds FC09, FC12, FC14, FC30 and FC31 significantly raised the total ROS by 148.3±2.1%, 144.2±5.9%, 112±3.1%, 134.8±10.3% and 140.7±5.7%, respectively. Interestingly, all compounds under investigation significantly raised the intracellular ROS within 1.5 h of exposure. After 24 h of exposure, only compounds FC01, FC07, FC30, and FC31 kept the intracellular level of ROS significantly higher than control cells (111.1±3.6, 113.8±4.3%, 110.4±2.2%, and 117.7±7.5%, respectively). On the other hand, the ROS level within cells treated with the IC50 of compounds FC09 and FC12 for 24 h was significantly lower than control cells (85.7±1.3 and 68.4±4.7, respectively). Apoptosis/necrosis differential assessment using annexin-V/FITC with PI as a counterstain coupled with flow cytometric analysis, showed that compounds FC01, FC09, and FC12 induced significant apoptosis as well as necrosis by 2-5 folds compared to control cells. Compound FC14 failed to induce any significant apoptosis or necrosis. In conclusion, trans-cinnamaldehyde and curcumin scaffold-based compounds under investigation, particularly FC01, FC09 and FC12 might represent promising candidates in anticancer molecules for further optimization. Citation Format: Abdel-Sattar M. Omar, Ahmed M. Al-Abd. Design, synthesis and anticancer properties of trans-cinnamaldehyde and curcumin based scaffolds compounds [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 6562.

The use of total standardized plant extracts is frequently used in low-income countries for several diseases. Solanum sp. and Annona sp. are edible folk herbs with reported uses for the treatment of several malignancies. Natural herb products and folk medicine might not be a potent anticancer and might be recommended for combination therapy. 5- FU is a commonly used antimetabolite chemotherapeutic agent used for the treatment of several neoplastic disorders. In the current work, we mathematically evaluated the influence of adding total standardized extract of A. cherimola and S. nigrum to the cytotoxic profile of 5-FU in head and neck cancer cells. Cytotoxicity assessment and combination analysis were calculated after MTT assays followed by fitting to the Emax model and calculating the combination index (CI-value). After 24 h exposure, both A. cherimola and S. nigrum extracts were more potent than 5-FU with IC50‘s of 29.4±4.4, 7.3±1.3 and 3.4±4.4 µg/ml, respectively. Both A. cherimola and S. nigrum extracts significantly decreased the IC50‘s of 5-FU to 5.2±0.55 and 7.6±0.85 µg/ml, respectively; however, the CI-values were indicative of additive and antagonistic interactions, respectively (0.91 and 2.49, respectively). After 48 h of exposure, the IC50‘s of 5-FU, A. cherimola and S. nigrum extracts were 3.1±0.45, 0.87±0.22 and 7.2±0.65 µg/ml, respectively. Similarly, a combination of A. cherimola or S. nigrum extracts with 5-FU showed additive and antagonistic interaction with CI-values of 1.05 and 3.37, respectively. After 72 h of exposure, the IC50‘s of 5-FU, A. cherimola and S. nigrum extracts were 1.9±0.1, 2.1±0.24 and 2.1±0.1 µg/ml, respectively. Similarly, a combination of A. cherimola and S. nigrum extracts with 5-FU showed additive and antagonistic interaction with CI-values of 1.2 and 2.21, respectively. Then, the CnT model was used to assess the relative influence of drug concentration and exposure time on the cytotoxic profile of treatments under investigation. For S. nigrum and its combination with 5-FU, n-values were 0.9 and 0.63 which is indicative of the relatively high influence of drug concentration. On the other hand, the n-value for 5-FU treatment was 0.37; this indicates a higher influence of drug exposure time compared to other treatments. The n-values of A. cherimola and its combination with 5-FU were 0.51 and 0.54, respectively; this indicates a comparable influence of both drug concentration and exposure time. Further PCR analysis showed over-expression of the apoptotic gene, BAX, after 5-FU combination with A. cherimola and decreased after combination with S. nigrum. In conclusion, some natural herbal remedies such as A. cherimola might influence the cytotoxic profile of 5-FU and particularly after short exposure time; while on the other hand, some herbal remedies such as S. nigrum significantly antagonize its cytotoxic activity against head and neck cancer cells and should be avoided during the treatment with 5-FU Citation Format: Serag Eldin I. Elbehairi, Fahad A. Alabbasi, Aly F. Mohamed, Nahla G. Mohamed, Mohammad I. Basuony, Mahmoud M. Salem, Metwaly M. Montaser, Mohammad Y. Alfaifi, Safaa Y. Eid, Ahmed M. Al-Abd. Mathematical analysis for the combinatorial cytotoxic properties of the standardized extract of Annona cherimola or Solanum nigrum with 5-FU against head and neck cancer cells [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 6561.

The microenvironment characteristics of solid tumors, renowned as barriers that harshly impeded many drug-delivery approaches, were precisely studied, investigated, categorized, divided, and subdivided into a complex diverse of barriers. These categories were further studied with a particular perspective, which makes all barriers found in solid-tumor micromilieu turn into different types of stimuli, and were considered triggers that can increase and hasten drug-release targeting efficacy. This review gathers data concerning the nature of solid-tumor micromilieu. Past research focused on the treatment of such tumors, the recent efforts employed for engineering smart nanoarchitectures with the utilization of the specified stimuli categories, the possibility of combining more than one stimuli for much-greater targeting enhancement, examples of the approved nanoarchitectures that already translated clinically as well as the obstacles faced by the use of these nanostructures, and, finally, an overview of the possible future implementations of smart-chemical engineering for the design of more-efficient drug delivery and theranostic systems and for making nanosystems with a much-higher level of specificity and penetrability features.

The use of anti-cancer adjuvant therapy is rationalized by potentiating the efficacy, and/or protecting from major side effects of chemotherapeutics. Thymoquinone (TQ) is a naturally occurring compound with cumulative evidence of anti-cancer properties. In this study, we assessed the chemomodulatory potential of TQ to gemcitabine (GCB) against human breast adenocarcinoma (MCF-7), and ductal carcinoma (T47D) cells. TQ showed cytotoxic effects against MCF-7 and T47D with IC50’s of 64.9 ± 14 µM and 165 ± 2 µM, respectively. The IC50’s of GCB against MCF-7 and T47D were 0.9 ± 0.18 µM and 14.3 ± 2.8 µM and were significantly reduced after combination with TQ to 0.058 ± 12 µM and 2.3 ± 0.2 µM, respectively. The CI- values were indicative of synergism in MCF-7 and T47D cells (0.15 and 0.30, respectively). Further investigation showed that GCB caused significant anti-proliferative effect reflected by increasing cell population in S-phase in both cell lines. TQ potentiated GCB-induced anti-proliferative activity in both cell lines. GCB induced considerable apoptosis in T47D cell line, and TQ significantly increased GCB-induced apoptotic effects by 1.5 to 3.6 folds. Interestingly, GCB, TQ and their combination induced significant autophagic cell death in the apoptosis defected MCF-7 cells. In addition, TQ, GCB and their combination depleted breast cancer associated stem cell (CD44(+)/CD24(−)/(low)) clone within MCF-7 and T47D cells by 3.8% to 27.5%. In conclusion, TQ showed promising chemomodulatory effects to GCB against breast cancer cells via inducing apoptosis, necrosis and autophagy, in addition to depleting tumor associated resistant stem cell fraction.

The Red Sea specimen of the marine sponge Hyrtios erectus (order Dictyoceratida) was found to contain scalarane-type sesterterpenes. 12-O-deacetyl-12,19-di-epi-scalarin (14), a new scalarane sesterterpenoid, along with fourteen previously-reported scalarane-type sesterterpenes (1–13 and 15) have been isolated. The chemical structures of the isolated compounds were elucidated on the basis of detailed 1D and 2D NMR spectral data and mass spectroscopy, as well as by comparison with reported data. The anti-Helicobacter pylori, antitubercular and cytotoxic activities of all fifteen compounds were evaluated to reveal the potency of Compounds 1, 2, 3, 4, 6, 7 and 10. Amongst these, Compounds 1, 3, 4, 6 and 10 displayed a promising bioactivity profile, possessing potent activities in the antitubercular and anti-H. pylori bioassay. Compounds 2 and 7 showed the most promising cytotoxic profile, while Compounds 1 and 10 showed a moderate cytotoxic profile against MCF-7, HCT-116 and HepG2 cell lines.

Finasteride (FSD), a specific competitive inhibitor of the steroid type-II 5α-reductase enzyme, is used in treatment of benign prostate hyperplasia (BPH) and male pattern baldness. The drug is of limited solubility that affect its dissolution and bioavailability. The aim was to study the effect of FSD particle size reduction on the pharmacokinetic, tissue distribution and cellular permeation. An optimized drug micro- and nano-particles were developed, characterized, administered to group of rats, and systemic pharmacokinetic and tissue distribution within target and not-target organs were determined using near-infrared (NIR) spectroscopy technique. Moreover, the cellular permeation of the prepared formulations through normal prostate epithelial cells was assessed and compared to pure FSD. The developed micro- and nano-particles were of 930 and 645 nm, respectively. Plasma maximum drug levels (Cmax) and overall exposure (AUC) of both formulations were not significantly higher than unformulated drug. However, micronized FSD achieved significant higher concentration within the target tissue (prostate) within the current study compared to pure drug and nano-sized formulation as well. Yet, this is explained by the higher sequestration ability of spleen tissue to the nano-sized formula compared to micro-sized FSD. At the cellular level, permeation of nano-sized FSD through prostate epithelial cells was superior to the unformulated FSD as well as the micro-sized drug formulation. FSD particle size reduction significantly influences its cellular permeation and to a lesser extend affect its systemic pharmacokinetics and tissue distribution after oral administration.

Three triterpenoidal derivatives [Sipholenol A (1), sipholenol L (2) and sipholenone A (3)] were isolated from the Red Sea sponge Siphonochalina sp. The structures were determined based on spectroscopic measurements (NMR, UV, IR and MS). The isolated compounds were evaluated for their cytotoxic activity against three cancer cell lines; HepG2, Caco-2 and HT-29. Moreover, the effects of these metabolites on cell cycle progression as well as cell cycle regulating proteins were assessed. Compounds 1, 2 and 3 showed moderate activity against HepG2 cells with IC50 values of 17.18 ± 1.18, 24.01 ± 0.59 and 35.06 ± 1.10 μM, respectively. Compounds 1 and 2 exerted a considerable antiproliferative effect with IC50 values of 4.80 ± 0.18 and 26.64 ± 0.30 μM, respectively, against Caco-2 cells. Finally, 1 and 2 exhibited antiproliferative activity against colorectal cancer cells (HT-29) with IC50 values of 24.65 ± 0.80 and 4.48 ± 0.1 μM, respectively. Cell cycle analysis indicated that these compounds induced cell cycle arrest particularly in G0/G1 and S phases. Furthermore, the triterpenoids increased the expression of cyclin-B1, cyclin-D1 and cleaved caspase-3, as determined by immunofluorescence, indicating an important role of apoptosis in cell death induced by these compounds.

Graphical abstract, Resistance of solid tumors to treatment is significantly attributed to pharmacokinetic reasons at both cellular and multi-cellular levels. Anticancer agent must be bio-available at the site of action in a cytotoxic concentration to exert its proposed activity. P-glycoprotein (P-gp) is a member of the ATP-dependent membrane transport proteins; it is known to pump substrates out of cells in ATP-dependent mechanism. The over-expression of P-gp in tumor cells reduces the intracellular drug concentrations, which decreases the cytotoxicity of a broad spectrum of antitumor drugs. Accordingly, P-gp inhibitors/blockers are potential enhancer for the cellular bioavailability of several clinically important anticancer drugs such as, anthracyclines, taxanes, vinca alkaloids, and podophyllotoxins. Besides several chemically synthesized P-gp inhibitors/blockers, some naturally occurring compounds and plant extracts were reported for their modulation of multidrug resistance; however, this review will focus only on major classes of naturally occurring inhibitors viz., flavonoids, coumarins, terpenoids, alkaloids and saponins.

Aim The present study was designed to investigate the effect of leptin on estrogen metabolism in prostatic cells. Main methods Malignant (PC-3) and benign (BPH-1) human prostate cells were treated with 17-β-hydroxyestradiol (1 μM) alone or in combination with leptin (0.4, 4, 40 ng/ml) for 72 h. Cell proliferation assay, immunocytochemical staining of estrogen receptor (ER), liquid chromatography–tandem mass spectrometry method (LC–MS) and semi-quantitative reverse transcriptase polymerase chain reaction (RT-PCR) were used. Key findings Cell proliferation assay demonstrated that leptin caused significant growth potentiation in both cells. Immunocytochemical staining showed that leptin significantly increased the expression of ER-α and decreased that of ER-β in PC-3 cells. LC–MS method revealed that leptin increased the concentration 4-hydroxyestrone and/or decreased that of 2-methoxyestradiol, 4-methoxyestradiol and 2-methoxyestrone. Interestingly, RT-PCR showed that leptin significantly up-regulated the expression of aromatase and cytochrome P450 1B1 (CYP1B1) enzymes; however down-regulated the expression of catechol-o-methyltransferase (COMT) enzyme. Significance These data indicate that leptin-induced proliferative effect in prostate cells might be partly attributed to estrogen metabolism. Thus, leptin might be a novel target for therapeutic intervention in prostatic disorders.