Gum acacia dietary fiber: Significance in immunomodulation, inflammatory diseases, and cancer.

Gum arabic/acacia (GA), derived from Acacia trees, is a versatile natural product offering a broad spectrum of applications. Its rich content of soluble dietary fibers, coupled with a low caloric profile, renders GA a valuable dietary component associated with numerous health benefits. Furthermore, its fermentation by gut microbiota yields short-chain fatty acids, renowned for their positive impact on health. Immunomodulation, a crucially regulated mechanism in the body, serves to fend off pathogenic infections by releasing pro-inflammatory cytokines. However, prolonged synthesis of these cytokines can lead to chronic inflammation, tissue damage, and potentially contribute to the development of autoimmune diseases and cancer. Hence, there is an urgent need to identify plant-based biomolecules that can effectively reduce inflammation and inhibit inflammation-induced complications or disorders. In this context, edible biomolecules like GA are gaining prominence for their noteworthy immunomodulatory properties. Therefore, in the present review we have explored the role of GA in immunomodulation, inflammation, and inflammation-associated metabolic diseases, and cancer.

Augmented CD133 expression in distal margin correlates with poor prognosis in colorectal cancer.

Pathological assessment of excised tumour and surgical margins in colorectal cancer (CRC) play crucial role in prognosis after surgery. Molecular assessment of margins could be more sensitive and informative than conventional histopathological analysis. Considering this view, we evaluated the distal surgical margins for expression of cancer stem cell (CSC) markers. Cellular and molecular assessment of normal, tumour and distal margin tissues were performed by flow cytometry, real-time q-PCR and immuno-histochemical analysis for CRC patients after tumour excision. CRC patients were evaluated for expression of CSC markers in their normal, tumour and distal tissues. Flow cytometry assay revealed CD133 and CD44 enriched cells in distal margin and tumour compared to normal colorectal tissues, which was further confirmed by immunohistochemistry. Most importantly, immunohistochemistry also revealed the enrichment of CSC markers expression in pathologically negative distal margins. Patients with distal margin enriched for CD133 expression showed an increased recurrence rate and decreased disease-free survival. This study proposes that although distal margin seems to be tumour free in conventional histopathological analysis, it could harbour cells enriched for CSC markers. Further CD133 could be a promising molecule to be used in molecular pathology for disease prognosis after surgery in CRC patients.

Oncogenic Actions of SKP2 Involves Deregulation of CDK1 Turnover Mediated by FOXM1.

Cyclin-dependent kinases (cdks) are central catalytic units of cell division cycle. Among the cdk family members, cdk1 has critical roles in multiple phases of the cell cycle. Aberrant expression or hyper-actions of cdk1 are tumorigenic and yet the complex oncogenic network that regulates its turnover is poorly understood. We found a hitherto unexplored functional connection between skp2 and cdk1 turn over. In vitro knockdown or overexpression of skp2 in cultured cells reduced or induced cdk1 expression indicating skp2 as a positive driver for cdk1. A partial inhibitory role for p27 was identified in this context. Interestingly, concurrent overexpression of skp2 and p27 favored cdk1 upregulation in vitro, which correlated well with similar observations in clinical tumor samples. We found that the transcription factor FOXM1 may play a central role in the skp2-cdk1 loop. Additional molecular involvement in the skp2-cdk1 loop was also explored. In conclusion, our results revealed hitherto unexplored p27 independent molecular mechanisms for skp2 driven tumor progression. Our results support the previous findings that skp2 may be a potential therapeutic target for the management of tumors. J. Cell. Biochem. 118: 797-807, 2017. © 2016 Wiley Periodicals, Inc.

Smurf E3 ubiquitin ligases at the cross roads of oncogenesis and tumor suppression.

Smad ubiquitin regulatory factors (Smurfs) belong to the HECT- family of E3 ubiquitin ligases and comprise mainly of two members, Smurf1 and Smurf2. Initially, Smurfs have been implicated in determining the competence of cells to respond to TGF-ß/BMP signaling pathway. Nevertheless, the intrinsic catalytic activity has extended the repertoire of Smurf substrates beyond the TGF-ß/BMP super family expanding its realm further to epigenetic modifications of histones governing the chromatin landscape. Through regulation of a large number of proteins in multiple cellular compartments, Smurfs regulate diverse cellular processes, including cell-cycle progression, cell proliferation, differentiation, DNA damage response, maintenance of genomic stability, and metastasis. As the genomic ablation of Smurfs leads to global changes in histone modifications and predisposition to a wide spectrum of tumors, Smurfs are also considered to have a novel tumor suppressor function. This review focuses on regulation network and biological functions of Smurfs in connection with its role in cancer progression. By providing a portrait of their protein targets, we intend to link the substrate specificity of Smurfs with their contribution to tumorigenesis. Since the regulation and biological functions of Smurfs are quite complex, understanding the oncogenic potential of these E3 ubiquitin ligases may facilitate the development of mechanism-based drugs in cancer treatment.

MicroRNA-532-3p Modulates Colorectal Cancer Cell Proliferation and Invasion via Suppression of FOXM1.

Colorectal cancer (CRC) is a heterogeneous disease and classified into various subtypes, among which transcriptional alterations result in CRC progression, metastasis, and drug resistance. Forkhead-box M1 (FOXM1) is a proliferation-associated transcription factor which is overexpressed in CRC and the mechanisms of FOXM1 regulation have been under investigation. Previously, we showed that FOXM1 binds to promoters of certain microRNAs. Database mining led to several microRNAs that might interact with FOXM1 3'UTR. The interactions between shortlisted microRNAs and FOXM1 3'UTR were quantitated by a dual-luciferase reporter assay. MicroRNA-532-3p interacted with the 3'UTR of the FOXM1 mRNA transcript most efficiently. MicroRNA-532-3p was ectopically overexpressed in colorectal cancer (CRC) cell lines, leading to reduced transcript and protein levels of FOXM1 and cyclin B1, a direct transcriptional target of FOXM1. Further, a clonogenic assay was conducted in overexpressed miR-532-3p CRC cells that revealed a decline in the ability of cells to form colonies and a reduction in migratory and invading potential. These alterations were reinforced at molecular levels by the altered transcript and protein levels of the conventional EMT markers E-cadherin and vimentin. Overall, this study identifies the regulation of FOXM1 by microRNA-532-3p via its interaction with FOXM1 3'UTR, resulting in the suppression of proliferation, migration, and invasion, suggesting its role as a tumor suppressor in CRC.

Cell-cycle analysis and micronuclei frequency reveals G0/G1 blockers as weak micronuclei inducers.

Micronuclei (MN) formation is generally attributed to error in DNA synthesis or mitosis, which are represented by the S or G(2)/M phase respectively, in the cell-cycle histogram. Interestingly, many of the known anticancer drugs target these cell-cycle phases to elicit cytotoxicity. Here, we attempted to identify whether any correlation exists between the cell-cycle effect and MN induction potential using various treatments. In addition, we tracked down MN in cycling cells to assess its final fate. We treated SiHa cells with various known drugs and correlated their effects on cell-cycle and MN frequency. MN-tracking studies were performed in peripheral mononuclear and siHa cells upon staining with Giemsa and ethidium bromide respectively. We observed MN induction by all the tested drugs irrespective of their basic effect on cell cycle. However, MN induction was more with drugs which interfere with the S or G(2)/M than the G(0)/G(1) phase. Our results indicate G(0)/G(1) blockers to be comparatively safer drugs. Additionally, our results show that expulsion out of cells may be one of the main fates of drug-induced MN.

Mitochondria-targeted biotin-conjugated BODIPYs for cancer imaging and therapy.

Two BODIPY-biotin conjugates KDP1 and KDP2 are designed and synthesized for targeted PDT applications. Both have good absorption with a high molar absorption coefficient and decent singlet oxygen generation quantum yields. The photosensitizers KDP1 and KDP2 were found to be localized in the mitochondria with excellent photocytotoxicity of up to 18.7 nM in MDA-MB-231 breast cancer cells. The cell death predominantly proceeded through the apoptosis pathway via ROS production.

Biocompatible Aza-BODIPY-Biotin Conjugates for Photodynamic Therapy of Cancer.

With an objective to develop efficient photosensitizers to cancerous tissues, we synthesized two novel biocompatible sensitizers based on aza-BODIPYs incorporated with heavy atoms and biotin moieties. The bioconjugates DPR2a and DPR2b exhibited a favorable absorption range (600-750 nm) with excellent triplet-state quantum yields (up to 79%) and singlet oxygen generation yields (up to 75%). In vitro photobiological investigations employing MDA-MB-231 breast cancer cell lines exhibited rapid cellular uptake, negligible dark toxicity, and high photocytotoxicity. The mechanism of cell death of these systems was predominantly due to the mitochondrial damage, leading to apoptosis mediated via the generation of singlet oxygen-triggered reactive oxygen species. The in vivo studies with the representative conjugate DPR2a employing female NOD/SCID mice models showed inhibition in tumor growth and significantly decreased tumor volume post photodynamic therapy (PDT) treatment. Our results validate that both DPR2a and DPR2b with iodine incorporation exhibit favorable and superior photophysical and photobiological aspects and demonstrate thereby their potential applications in imaging and PDT of cancer.

Drug-induced senescence generates chemoresistant stemlike cells with low reactive oxygen species.

Tumor recurrence after chemotherapy or radiation remains a major obstacle to successful cancer treatment. A subset of cancer cells, termed cancer stem cells, can elude conventional treatments and eventually regenerate a tumor that is more aggressive. Despite the large number of studies, molecular events that govern the emergence of aggressive therapy-resistant cells with stem cell properties after chemotherapy are poorly defined. The present study provides evidence for the rare escape of tumor cells from drug-induced cell death, after an intermediate stay in a non-cycling senescent stage followed by unstable multiplication characterized by spontaneous cell death. However, some cells appear to escape and generate stable colonies with an aggressive tumor stem cell-like phenotype. These cells displayed higher CD133 and Oct-4 expression. Notably, the drug-selected cells that contained low levels of reactive oxygen species (ROS) also showed an increase in antioxidant enzymes. Consistent with this in vitro experimental data, we observed lower levels of ROS in breast tumors obtained after neoadjuvant chemotherapy compared with samples that did not receive preoperative chemotherapy. These latter tissues also expressed enhanced levels of ROS defenses with enhanced expression of superoxide dismutase. Higher levels of Oct-4 and CD133 were also observed in tumors obtained after neoadjuvant chemotherapy. Further studies provided evidence for the stabilization of Nrf2 due to reduced 26 S proteasome activity and increased p21 association as the driving signaling event that contributes to the transition from a high ROS quiescent state to a low ROS proliferating stage in drug-induced tumor stem cell enrichment.

Evaluation of triblock copolymeric micelles of δ- valerolactone and poly (ethylene glycol) as a competent vector for doxorubicin delivery against cancer.

BACKGROUND: Specific properties of amphiphilic copolymeric micelles like small size, stability, biodegradability and prolonged biodistribution have projected them as promising vectors for drug delivery. To evaluate the potential of δ-valerolactone based micelles as carriers for drug delivery, a novel triblock amphiphilic copolymer poly(δ-valerolactone)/poly(ethylene glycol)/poly(δ-valerolactone) (VEV) was synthesized and characterized using IR, NMR, GPC, DTA and TGA. To evaluate VEV as a carrier for drug delivery, doxorubicin (DOX) entrapped VEV micelles (VEVDMs) were prepared and analyzed for in vitro antitumor activity. RESULTS: VEV copolymer was successfully synthesized by ring opening polymerization and the stable core shell structure of VEV micelles with a low critical micelle concentration was confirmed by proton NMR and fluorescence based method. Doxorubicin entrapped micelles (VEVDMs) prepared using a modified single emulsion method were obtained with a mean diameter of 90 nm and high encapsulation efficiency showing a pH dependent sustained doxorubicin release. Biological evaluation in breast adenocarcinoma (MCF7) and glioblastoma (U87MG) cells by flow cytometry showed 2-3 folds increase in cellular uptake of VEVDMs than free DOX. Block copolymer micelles without DOX were non cytotoxic in both the cell lines. As evaluated by the IC50 values VEVDMs induced 77.8, 71.2, 81.2% more cytotoxicity in MCF7 cells and 40.8, 72.6, 76% more cytotoxicity in U87MG cells than pristine DOX after 24, 48, 72 h treatment, respectively. Moreover, VEVDMs induced enhanced apoptosis than free DOX as indicated by higher shift in Annexin V-FITC fluorescence and better intensity of cleaved PARP. Even though, further studies are required to prove the efficacy of this formulation in vivo the comparable G2/M phase arrest induced by VEVDMs at half the concentration of free DOX confirmed the better antitumor efficacy of VEVDMs in vitro. CONCLUSIONS: Our studies clearly indicate that VEVDMs possess great therapeutic potential for long-term tumor suppression. Furthermore, our results launch VEV as a promising nanocarrier for an effective controlled drug delivery in cancer chemotherapy.

STIL Endows Oncogenic and Stem-Like Attributes to Colorectal Cancer Plausibly by Shh and Wnt Signaling.

The discovery of a potent gene regulating tumorigenesis and drug resistance is of high clinical importance. STIL is an oncogene; however, its molecular associations and role in colorectal oncogenesis are unknown. In this study, we have explored the role of STIL gene in tumorigenesis and studied its molecular targets in colorectal cancer (CRC). STIL silencing reduced proliferation and tumor growth in CRC. Further, STIL was found to regulate stemness markers CD133 and CD44 and drug resistant markers thymidylate synthase, ABCB1, and ABCG2 both in in-vitro and in-vivo CRC models. In addition, high expression of STIL mRNA was found to be associated with reduced disease-free survival in CRC cases. Interestingly, we observed that STIL-mediated regulation of stemness and drug resistant genes is not exclusively governed by Sonic hedgehog (Shh) signaling. Remarkably, we found STIL regulate ß-catenin levels through p-AKT, independent of Shh pathway. This partially answers Shh independent regulatory mechanism of cancer stem cell (CSC) markers by STIL. Our study suggests an instrumental role of STIL in molecular manifestation of CRC and progression.

Loss of cks1 homeostasis deregulates cell division cycle.

Genetic and biochemical studies have provided considerable insight into the multiple functions of cyclin-dependent kinase subunit (cks)1 in cell division cycle. In addition to enhanced substrate targeting by specific ubiquitin ligases SCF(skp2) and APC/C, its direct interaction with proteasome components normalizes multiple cell cycle regulators. Importantly, it also acts as a transcriptional regulator. cks1 overexpression reflects poor prognosis in malignancy thus indicating its possible role in tumour diagnosis and management. The present review compiles the multiple functional roles of cks1 in cell division with specific emphasis on its molecular mechanisms. Its docking functions and the possible downstream proteolytic and transcriptional targets are described. The spatial configuration of cks1-cdk2 complex and the structural organization of cks1-p27-skp2 assembly required for p27 ubiquitination are discussed in detail. In addition to enhanced p27 degradation, the possible other mechanisms which underlie its pathological functions in human cancer progression are also discussed. Though there are apparent gaps in information, the turnover mechanism of cks1 is well addressed and presents opportunity to exploit the target for disease management.

Picolyl Porphyrin Nanostructures as a Functional Drug Entrant for Photodynamic Therapy in Human Breast Cancers.

The major challenge in photodynamic therapy (PDT) is to discover versatile photosensitizers (PSs) that possess good solubility in biological media, enhanced singlet oxygen generation efficacy, and photodynamic activity. Working in this direction, we synthesized a picolylamine-functionalized porphyrin conjugate, compound 1, and its zinc complex compound 2. Compound 1 forms spherical structures in methanol, whereas compound 2 exhibited vesicular structures. Compared to the existing PSs like foscan and photofrin, compound 2 exhibited a high singlet oxygen generation efficiency and triplet quantum yield. The complex also showed good water solubility, and its PDT activity was demonstrated through in vitro studies using MDA-MB 231 breast cancer cells. The mechanism of biological activity evaluated using various techniques proved that the active compound 2 induced predominantly singlet oxygen-triggered apoptosis-mediated cancerous cell death. Our results demonstrate that zinc insertion in the picolyl porphyrin induces an enhanced triplet excited state, and the singlet oxygen yields quantitatively and imparts excellent in vitro photodynamic activity, thereby demonstrating their pertinence as a nanodrug in future photobiological applications.

Aza-BODIPY nanomicelles as versatile agents for the in vitro and in vivo singlet oxygen-triggered apoptosis of human breast cancer cells.

Herein, we synthesised four aza-BODIPY dyes (1-4) with the singlet oxygen generation quantum yield values of ca. 65-85%. Furthermore, we formulated a nanomedicine by encapsulating these dyes into an amphiphilic micelle, DSPE. The spherical nanomicelles formed were characterized using photophysical and morphological analyses, and their in vitro and in vivo photodynamic efficacies were investigated. One of the conjugates, DSPE-1, showed the lowest IC50 value of 2 µM against a human breast cancer cell line (MDA MB 231). The mechanism of photodynamic activity has been evaluated by employing different biophysical and morphological assays, which confirmed apoptotic cell death (ca. 80-90%) predominantly through the involvement of reactive oxygen species. Interestingly, we observed that 2 mg kg-1DSPE-1 induced enhanced apoptosis and efficient inhibition of the growth of breast tumor xenografts in NOD/SCID mice models. Herein, we demonstrated the application of aza-BODIPY nanomicelles in photodynamic therapy for the first time, and our results revealed that the DSPE-BODIPY nanomicelles enhanced the cellular uptake as well as the photodynamic activity, thereby demonstrating the use of these nanomicelles as efficient sensitizers in biological applications.

Biology of PPAR gamma in cancer: a critical review on existing lacunae.

Peroxisomal proliferator activated receptor gamma (PPARgamma) belongs to the family of nuclear hormone receptors (NHRs), which directly regulate transcription of target genes. The regulatory role of this receptor on lipid metabolism and insulin sensitization is well established. Recently, the overexpression of this receptor in many human cancers has been identified and understanding its biological significance forms the current theme. PPARgamma activation by specific agonists leads to growth inhibition, apoptosis and differentiation of tumor cells. PPARgamma possess evident tumor promoting properties but the receptor independent effects of its ligands compound the understanding of its biology in cancers. This review highlights the multifaceted role of PPARgamma in cancer progression with specific reference to colon, breast, gastric, lung and urological cancers. Molecular events as well as the mediators involved are analyzed in detail along with PPARgamma independent effects of ligands under each cancer type. The crucial cross talk that exists between Wnt and PPARgamma signaling is also summarized. An attempt has been made to identify the existing lacunae in understanding the biology of PPARgamma in cancers along with suggestions for possible rectification.

Bis(3,5-diiodo-2,4,6-trihydroxyphenyl)squaraine photodynamic therapy disrupts redox homeostasis and induce mitochondria-mediated apoptosis in human breast cancer cells.

Photodynamic therapy (PDT) is a clinically established and highly evolving treatment modality for cancer. PDT utilizes a light responsive drug called photosensitizer that selectively destroys tumor cells upon light irradiation. Squaraines are a class of dyes possessing all favorable characteristics of a photosensitizer and have been considered to be a potent candidate for next generation PDT. In this study we chose an iodo derivative of squaraine called diiodo-squaraine (bis(3, 5-diiodo-2,4,6-trihydroxyphenyl)squaraine) which has been reported for its tumor specificity but least studied for its cellular and molecular functions. Our studies revealed that the iodo derivative of squaraine possess maximum photodynamic activity in human breast cancer cells MDA- MB- 231 and had very little cytotoxicity in normal breast cells MCF-10A. We analyzed its pro and anti-apoptotic events initiated by oxidative stress exploring a proteomic approach and delineated other critical molecular pathways and key proteins involved in regulating the complex network of cellular response upon PDT. Our study showed that, diiodo- squaraines predominantly accumulate in mitochondria and induce mitochondria-mediated apoptosis. Our study also reveals the novel mechanistic role of diiodo-squaraines to induce oxidative stress there by activating both protective and death inducing pathways post PDT.

Dual drug delivery of 5-fluorouracil (5-FU) and methotrexate (MTX) through random copolymeric nanomicelles of PLGA and polyethylenimine demonstrating enhanced cell uptake and cytotoxicity.

We now report the synthesis of a random copolymer of poly-lactic-co-glycolic acid (PLGA) grafted branched polyethylenimine (BPEI) and the use of it as a multi drug delivery system (DDS). The methotrexate (MTX) was conjugated to BPEI through DCC/NHS chemistry. The copolymer-drug conjugate (PBP-MTX) was characterised by FT-IR and (1)H NMR spectroscopy. The PBP-MTX was converted into nanomicelles with entrapped 5-fluorouracil (5-FU) through nanoprecipitation technique. The size, shape, morphology and surface charge of the nanomicelles were confirmed using different techniques. The thermal behaviour and distribution of both conjugated and entrapped drug through the polymeric matrix were assessed by differential scanning calorimetry (DSC) and powder X-ray diffraction analysis (PXRD). In vitro drug release pattern of the nanomicelles was examined to ascertain the release pattern of two drugs namely 5-FU and MTX. The cellular uptake studies demonstrated higher uptake of the nanomicelles in colon cancer cell line HCT 116. Further the cytotoxicity evaluation of nanomicelles illustrated promising action which confirms the use of the system as a potential DDS to colon cancer.

Folic acid conjugated δ-valerolactone-poly(ethylene glycol) based triblock copolymer as a promising carrier for targeted doxorubicin delivery.

The aim of this study is to test the hypothesis that the newly synthesized poly(δ-valerolactone)/poly(ethylene glycol)/poly(δ-valerolactone) (VEV) copolymer grafted with folic acid would impart targetability and further enhance the anti-tumor efficacy of doxorubicin (DOX). Here, folic acid conjugated VEV (VEV-FOL) was synthesized by a modified esterification method and characterized using IR and NMR. DOX loaded VEV-FOL micelles were synthesized using a novel solvent evaporation method and were obtained with a mean diameter of 97 nm with high encapsulation efficiency and sustained in vitro release profile. Comparative studies of polymer micelles with and without folate for cellular uptake and cytotoxicity were done on folate receptor-positive breast cancer cell line, MDAMB231. The intracellular uptake tests showed significant increase in folate micellar uptake when compared to non-folate-mediated micelles. MTT assay followed by apoptosis assays clearly indicated that folate decorated micelles showed significantly better cytotoxicity (IC50 = 0.014 µM) and efficiency to induce apoptosis than other treated groups. Moreover, a significant G2/M arrest was induced by DOX loaded VEV-FOL micelles at a concentration where free drug failed to show any activity. Thus, our results show that the folic acid-labeled VEV copolymer is a promising biomaterial with controlled and sustainable tumor targeting ability for anticancer drugs which can open new frontiers in the area of targeted chemotherapy.