Alterations in membrane fluidity and dynamics in experimental colon cancer and its chemoprevention by diclofenac

Tailor-made vincristine-liposomes for tumor targeting

To ensure selective targeting based on membrane fluidity and physico-chemical compatibility between the biological membrane of the target cell and the lipid membrane of the liposomes carriers. Lipid-based carriers as liposomes with varying membrane fluidities were designed for delivering vincristine, an anti-tumor compound derived from Madagascar's periwinkle. Liposomes, loaded with vincristine, were tested on prostate, colon, and breast cancer cell lines alongside non-tumor controls. Results showed that vincristine-loaded liposomes with fluid membranes significantly decreased the viability of cancer cell lines compared to controls. Confocal microscopy revealed the intracellular release of vincristine, evidenced by disrupted mitosis-specific labeling of actin filaments in metastatic prostate cell lines. This highlights the crucial role of membrane fluidity in the development of lipid-based drug carriers, offering a promising and cost-effective option for targeting cancer cells as an alternative to conventional strategies.

Therapeutic potential of Phycocyanin in gastrointestinal cancers and related disorders

Gastrointestinal cancer is the most fatal cancer worldwide. The etiology of gastrointestinal cancer has yet to be fully characterized. Alcohol consumption, obesity, tobacco, Helicobacter pylori and gastrointestinal disorders, including gastroesophageal reflux disease, gastric ulcer, colon polyps and non-alcoholic fatty liver disease are among the several risks factors for gastrointestinal cancers. Phycocyanin which is abundant in Spirulina. Phycocyanin, a member of phycobiliprotein family with intense blue color, is an anti-diabetic, neuroprotective, anti-oxidative, anti-inflammatory, and anticancer compound. Evidence exists supporting that phycocyanin has antitumor effects, exerting its pharmacological effects by targeting a variety of cellular and molecular processes, i.e., apoptosis, cell-cycle arrest, migration and Wnt/β-catenin signaling. Phycocyanin has also been applied in treatment of several gastrointestinal disorders such as, gastric ulcer, ulcerative colitis and fatty liver that is known as a risk factor for progression to cancer. Herein, we summarize various cellular and molecular pathways that are affected by phycocyanin, its efficacy upon combined drug treatment, and the potential for nanotechnology in its gastrointestinal cancer therapy.

Human Intestinal Defensin 5 Ameliorates the Sensitization of Colonic Cancer Cells to 5-Fluorouracil

BACKGROUND AND AIM

The increasing dilemma of multidrug-resistant cancer cells in response to currently available chemotherapeutic drugs and their associated side effect(s), calls for the investigation of alternative anticancer advances and molecules. Therefore, the present study aimed to elucidate the combinatorial potential against colon cancer of human defensin 5 in combination with 5-fluorouracil (5-FU), and against 5-FU resistant colon tumor cells.

METHODS

The in vivo combinatorial potential of HD-5 with 5-FU was elucidated in terms of tumor morphometrics, apoptosis assay, surface morphology histology of the colon(s), and transcriptional alterations. Changes in membrane dynamics with mucin expression were evaluated by fluorescence microscopy and histochemistry. The in vitro activity of the peptide/drug conjunction was explored by phase contrast microscopy, MTT, LDH assay, and AO/EtBr staining. Chemoresistance to 5-FU was determined by phase contrast microscopy, MTT assay, annexin V-FITC/PI flow cytometry, and MDR-1, Bak, and Bax expression.

RESULTS

In vivo decreases in tumor parameters, with a marked increase in apoptosis and neutrophil infiltrations indicated restoration of normal architecture with improved mucin content in the treated colons. This happened with substantial changes in key molecular markers of the intrinsic apoptotic cascade. Membrane dynamics revealed that peptides and chemotherapeutic drugs could bind to cancerous cells by taking advantage of altered levels of membrane fluidity.

CONCLUSION

Peptide treatment of drug-resistant Caco-2 cells promotes enhanced 5-FU uptake, in contrast to when cells were treated with 5-FU alone. Hence, HD-5 as an adjunct to 5-FU, exhibited strong cancer cell killing even against 5-FU-resistant tumorigenic cells.

Correlation of Plasma Membrane Microviscosity and Cell Stiffness Revealed via Fluorescence-Lifetime Imaging and Atomic Force Microscopy

The biophysical properties of cells described at the level of whole cells or their membranes have many consequences for their biological behavior. However, our understanding of the relationships between mechanical parameters at the level of cell (stiffness, viscoelasticity) and at the level of the plasma membrane (fluidity) remains quite limited, especially in the context of pathologies, such as cancer. Here, we investigated the correlations between cells' stiffness and viscoelastic parameters, mainly determined via the actin cortex, and plasma membrane microviscosity, mainly determined via its lipid profile, in cancer cells, as these are the keys to their migratory capacity. The mechanical properties of cells were assessed using atomic force microscopy (AFM). The microviscosity of membranes was visualized using fluorescence-lifetime imaging microscopy (FLIM) with the viscosity-sensitive probe BODIPY 2. Measurements were performed for five human colorectal cancer cell lines that have different migratory activity (HT29, Caco-2, HCT116, SW 837, and SW 480) and their chemoresistant counterparts. The actin cytoskeleton and the membrane lipid composition were also analyzed to verify the results. The cell stiffness (Young's modulus), measured via AFM, correlated well (Pearson r = 0.93) with membrane microviscosity, measured via FLIM, and both metrics were elevated in more motile cells. The associations between stiffness and microviscosity were preserved upon acquisition of chemoresistance to one of two chemotherapeutic drugs. These data clearly indicate that mechanical parameters, determined by two different cellular structures, are interconnected in cells and play a role in their intrinsic migratory potential.

Assessing hypoxic damage to placental trophoblasts by measuring membrane viscosity of extracellular vesicles

INTRODUCTION

As highly sophisticated intercellular communication vehicles in biological systems, extracellular vesicles (EVs) have been investigated as both promising liquid biopsy-based disease biomarkers and drug delivery carriers. Despite tremendous progress in understanding their biological and physiological functions, mechanical characterization of these nanoscale entities remains challenging due to the limited availability of proper techniques. Especially, whether damage to parental cells can be reflected by the mechanical properties of their EVs remains unknown.

METHODS

In this study, we characterized membrane viscosities of different types of EVs collected from primary human trophoblasts (PHTs), including apoptotic bodies, microvesicles and small extracellular vesicles, using fluorescence lifetime imaging microscopy (FLIM). The biochemical origin of EV membrane viscosity was examined by analyzing their phospholipid composition, using mass spectrometry.

RESULTS

We found that different EV types derived from the same cell type exhibit different membrane viscosities. The measured membrane viscosity values are well supported by the lipidomic analysis of the phospholipid compositions. We further demonstrate that the membrane viscosity of microvesicles can faithfully reveal hypoxic injury of the human trophoblasts. More specifically, the membrane of PHT microvesicles released under hypoxic condition is less viscous than its counterpart under standard culture condition, which is supported by the reduction in the phosphatidylethanolamine-to-phosphatidylcholine ratio in PHT microvesicles.

DISCUSSION

Our study suggests that biophysical properties of released trophoblastic microvesicles can reflect cell health. Characterizing EV's membrane viscosity may pave the way for the development of new EV-based clinical applications.

Lipidomic landscape in cancer: Actionable insights for membrane-based therapy and diagnoses

Cancer cells display altered cellular lipid metabolism, including disruption in endogenous lipid synthesis, storage, and exogenous uptake for membrane biogenesis and functions. Altered lipid metabolism and, consequently, lipid composition impacts cellular function by affecting membrane structure and properties, such as fluidity, rigidity, membrane dynamics, and lateral organization. Herein, we provide an overview of lipid membranes and how their properties affect cellular functions. We also detail how the rewiring of lipid metabolism impacts the lipidomic landscape of cancer cell membranes and influences the characteristics of cancer cells. Furthermore, we discuss how the altered cancer lipidome provides cues for developing lipid-inspired innovative therapeutic and diagnostic strategies while improving our limited understanding of the role of lipids in cancer initiation and progression. We also present the arcade of membrane characterization techniques to cement their relevance in cancer diagnosis and monitoring of treatment response.

Tinospora Cordifolia and Arabinogalactan in combination modulates benzo(a)pyrene-induced genotoxicity during lung carcinogenesis

The present study explored the effects of combination of Tinospora cordifolia and Arabinogalactan on surface membrane dynamics and programmed cell deaths in rat model of lung cancer. The rats were divided into different groups namely normal control, benzo(a)pyrene (BP) treated, BP + Tinospora cordifolia (TC)-treated, BP + Arabinogalactan (A)-treated and BP + TC + A-treated groups. Significant changes were observed in the membrane dynamics of rats treated with BP. The carcinogen treatment demonstrated a marked decrease in membrane microviscosity. Also, excimer/monomer ratio and fluidity parameters of BP treated rats showed significant rise. On the other hand, combination of Tinospora cordifolia and Arabinogalactan improvised surface membrane dynamics. Moreover, micronuclei formation along with protein expression of bcl-2 showed significant increase in the lungs of BP treated rats. The combined treatment of Tinospora cordifolia and Arabinogalactan moderated the micronuclei formation in BP treated rats. Also, the combined treatment regulated the protein expressions of bcl-2 in BP-treated rats. As a result, marked improvement was noticed in apoptosis of BP treated cells treated with combination treatment. This study concludes that the Tinospora cordifolia and Arabinogalactan in combination improve the surface membrane dynamics and apoptosis in BP-treated rats.

Monomethyl Auristatin E Grafted-Liposomes to Target Prostate Tumor Cell Lines

Novel nanomedicines have been engineered to deliver molecules with therapeutic potentials, overcoming drawbacks such as poor solubility, toxicity or short half-life. Lipid-based carriers such as liposomes represent one of the most advanced classes of drug delivery systems. A Monomethyl Auristatin E (MMAE) warhead was grafted on a lipid derivative and integrated in fusogenic liposomes, following the model of antibody drug conjugates. By modulating the liposome composition, we designed a set of particles characterized by different membrane fluidities as a key parameter to obtain selective uptake from fibroblast or prostate tumor cells. Only the fluid liposomes made of palmitoyl-oleoyl-phosphatidylcholine and dioleoyl-phosphatidylethanolamine, integrating the MMAE-lipid derivative, showed an effect on prostate tumor PC-3 and LNCaP cell viability. On the other hand, they exhibited negligible effects on the fibroblast NIH-3T3 cells, which only interacted with rigid liposomes. Therefore, fluid liposomes grafted with MMAE represent an interesting example of drug carriers, as they can be easily engineered to promote liposome fusion with the target membrane and ensure drug selectivity.

The Agonist Action of Alkylphenols on TRPA1 Relates to Their Effects on Membrane Lipid Order: Implications for TRPA1-Mediated Chemosensation

The Transient Receptor Potential Ankyrin 1 cation channel (TRPA1) is a broadly-tuned chemosensor expressed in nociceptive neurons. Multiple TRPA1 agonists are chemically unrelated non-electrophilic compounds, for which the mechanisms of channel activation remain unknown. Here, we assess the hypothesis that such chemicals activate TRPA1 by inducing mechanical perturbations in the plasma membrane. We characterized the activation of mouse TRPA1 by non-electrophilic alkylphenols (APs) of different carbon chain lengths in the para position of the aromatic ring. Having discarded oxidative stress and the action of electrophilic mediators as activation mechanisms, we determined whether APs induce mechanical perturbations in the plasma membrane using dyes whose fluorescence properties change upon alteration of the lipid environment. APs activated TRPA1, with potency increasing with their lipophilicity. APs increased the generalized polarization of Laurdan fluorescence and the anisotropy of the fluorescence of 1,6-diphenyl-1,3,5-hexatriene (DPH), also according to their lipophilicity. Thus, the potency of APs for TRPA1 activation is an increasing function of their ability to induce lipid order and membrane rigidity. These results support the hypothesis that TRPA1 senses non-electrophilic compounds by detecting the mechanical alterations they produce in the plasma membrane. This may explain how structurally unrelated non-reactive compounds induce TRPA1 activation and support the role of TRPA1 as an unspecific sensor of potentially noxious compounds.

Anticancer potential of human intestinal defensin 5 against 1, 2-dimethylhydrazine dihydrochloride induced colon cancer: A therapeutic approach

The escalating predicament of multidrug resistant cancer cells and associated side effects of conventional chemotherapy necessitates the exploration of alternative anticancer therapies. The present study evaluated anticancer therapeutic potential of human defensin 5 (HD-5) against colon cancer. The in vivo anticancer efficacy of HD-5 against 1,2-dimethylhydrazine (DMH) induced colon cancer was elucidated in terms of tumor biostatistics, number of aberrant crypt foci (ACF), in situ apoptosis assay,changes in morphological as well as histological architecture of colon(s). The direct interaction of peptide was investigated by incubating peptide with normal and/or cancerous colonocytes followed by phase contrast, Hoechst 3342 and AO/PI staining as well as confocal microscopy. Changes in membrane dynamics were evaluated by MC 540 and N-NBD-PE staining. In vivo decrease(s) in tumor parameters, number of aberrant crypt foci along with marked increase in the rate of apoptosis was observed.H&E staining revealed neutrophils infiltration and restoration of normal architecture in treated colon(s) which was consistent with scanning electron microscopic observations. Furthermore, non-membranolytic mechanism was found to be acquired by peptide as it could traverse cell membrane gaining access to nucleus and cytoplasm thereby disintegrating cellular architecture. MC 540 and NBD-PE staining revealed that peptide could bind to cancerous cells by taking advantage of altered fluidity levels. Our results indicated that HD-5 exhibited strong cancer cell killing and does not affect normal host cells. The peptide can be exploited as promising option to combat developing menace of colon cancer and/or can at least be used as an adjunct to present day chemotherapies.

Imatinib modulates pro-inflammatory microenvironment with angiostatic effects in experimental lung carcinogenesis

Lung cancer has second highest rate of incidence and mortality around the world. Smoking cigarettes is the main stream cause of lung carcinogenesis along with other factors such as spontaneous mutations, inactivation of tumor suppressor genes. The present study was aimed to identify the mechanistic role of Imatinib in the chemoprevention of experimental lung carcinogenesis in rat model. Gross morphological observations for tumor formation, histological examinations, RT-PCR, Western blotting, fluorescence spectroscopy and molecular docking studies were performed to elucidate the chemopreventive effects of Imatinib and support our hypothesis by various experiments. It is evident that immuno-compromised microenvironment inside solid tumors is responsible for tumor progression and drug resistance. Therefore, it is inevitable to modulate the pro-inflammatory signaling inside solid tumors to restrict neoangiogenesis. In the present study, we observed that Imatinib could downregulate the inflammatory signaling and also attributed angiostatic effects. Moreover, Imatinib also altered the biophysical properties of BAL cells such as plasma membrane potential, fluidity and microviscosity to restrict their infiltration and thereby accumulation to mount immuno-compromised environment inside the solid tumors during angiogenesis. Our molecular docking studies suggest that immunomodulatory and angiostatic properties of Imatinib could be either independent of each other or just a case of synergistic pleiotropy. Imatinib was observed to activate the intrinsic or mitochondrial pathway of apoptosis to achieve desired effects in cancer cell killings. Interestingly, binding of Imatinib inside the catalytic domain of PARP-1 also suggests that it has caspase-independent properties in promoting cancer cell deaths.

Expanding the Scope of Reporting Nanoparticles: Sensing of Lipid Phase Transitions and Nanoviscosities in Lipid Membranes

Biological membrane fluidity and thus the local viscosity in lipid membranes are of vital importance for many life processes and implicated in various diseases. Here, we introduce a novel viscosity sensor design for lipid membranes based on a reporting nanoparticle, a sulfated dendritic polyglycerol (dPGS), conjugated to a fluorescent molecular rotor, indocarbocyanine (ICC). We show that dPGS-ICC provides high affinity to lipid bilayers, enabling viscosity sensing in the lipid tail region. The systematic characterization of viscosity- and temperature-dependent photoisomerization properties of ICC and dPGS-ICC allowed us to determine membrane viscosities in different model systems and in living cells using fluorescence lifetime imaging (FLIM). dPGS-ICC distinguishes between ordered lipids and the onset of membrane defects in small unilamellar single lipid vesicles and is highly sensitive in the fluid phase to small changes in viscosity introduced by cholesterol. In microscopy-based viscosity measurements of large multilamellar vesicles, we observed an order of magnitude more viscous environments by dPGS-ICC, lending support to the hypothesis of heterogeneous nanoviscosity environments even in single lipid bilayers. The existence of such complex viscosity structures could explain the large variation in the apparent membrane viscosity values found in the literature, depending on technique and probe, both for model membranes and live cells. In HeLa cells, a tumor-derived cell line, our nanoparticle-based viscosity sensor detects a membrane viscosity of ∼190 cP and is able to discriminate between cell membrane and intracellular vesicle localization. Thus, our results show the versatility of the dPGS-ICC nano-conjugate in physicochemical and biomedical applications by adding a new analytical functionality to its medical properties.

Dietary zerumbone from shampoo ginger: new insights into its antioxidant and anticancer activity

The dietary sesquiterpene dienone zerumbone (ZER) selectively targets cancer cells, inducing mitochondrial dysfunction and apoptosis, and protects non-cancerous cells towards oxidative stress and insult. This study examines the in vitro effects of ZER on lipid peroxidation in biological systems (cholesterol and phospholipid membrane oxidation) and explores its antitumor action in terms of its ability to modulate cancer cell lipid profile. Evaluation of the antioxidant activity of ZER showed that this compound is unable to trap lipoperoxyl radicals per se. ZER significantly modulated the total lipid and fatty acid profiles in cancer cells, inducing marked changes in the phospholipid/cholesterol ratio, with significant decreases in the levels of oleic and palmitic acids and a marked increase of stearic acid. Cell-based fluorescent measurements of intracellular membranes and lipid droplets using the Nile Red staining technique showed that in cancer cells, ZER induced significant accumulation of cytosolic lipid droplets and altered cell membrane organization/protein dynamics, depolarizing the mitochondrial membranes and inducing apoptosis and alteration of nuclear morphology. The modulatory activity of ZER on the total lipid and fatty acid profiles and lipid droplets may therefore represent another possible mechanism of its anticancer properties.

Differential interactions of bacterial lipopolysaccharides with lipid membranes: implications for TRPA1-mediated chemosensation

Bacterial lipopolysaccharides (LPS) activate the TRPA1 cation channels in sensory neurons, leading to acute pain and inflammation in mice and to aversive behaviors in fruit flies. However, the precise mechanisms underlying this effect remain elusive. Here we assessed the hypothesis that TRPA1 is activated by mechanical perturbations induced upon LPS insertion in the plasma membrane. We asked whether the effects of different LPS on TRPA1 relate to their ability to induce mechanical alterations in artificial and cellular membranes. We found that LPS from E. coli, but not from S. minnesota, activates TRPA1. We then assessed the effects of these LPS on lipid membranes using dyes whose fluorescence properties change upon alteration of the local lipid environment. E. coli LPS was more effective than S. minnesota LPS in shifting Laurdan’s emission spectrum towards lower wavelengths, increasing the fluorescence anisotropy of diphenylhexatriene and reducing the fluorescence intensity of merocyanine 540. These data indicate that E. coli LPS induces stronger changes in the local lipid environment than S. minnesota LPS, paralleling its distinct ability to activate TRPA1. Our findings indicate that LPS activate TRPA1 by producing mechanical perturbations in the plasma membrane and suggest that TRPA1-mediated chemosensation may result from primary mechanosensory mechanisms.

The effectiveness of cyclooxygenase-2 inhibitors and evaluation of angiogenesis in the model of experimental colorectal cancer

Colorectal cancer (CRC) is an important cause of cancer-related deaths worldwide. Early diagnosis and treatment of CRCs are of importance for improving the survival. In the present study, we studied the effects of nonsteroidal anti-inflammatory drugs (NSAIDs)-induced chemopreventive effects on tumor development incidence and angiogenesis in experimental CRC rats. 1,2-Dimethylhydrazine dihydrochloride (DMH) was used as cancer-inducing agent and two NSAIDs (celecoxib and diclofenac) were given orally as chemopreventive agents. Histopathological and immuno histochemical evaluations were performed in colorectal tissue samples, whereas angiogenesis parameters were studied in blood samples. Histopathological examination showed that adenocarcinoma (62.5%), dysplastic changes (31.25%) and inflammattory changes (6.25%) were detected in DMH group, whereas no pathological change was observed in control rats. In treatment groups, there was marked decrease in adenocarcinoma rate (30% and 10%, respectively). A significant increase was detected in MMP-2, MMP-9 levels and MMP-2/TIMP-2 ratio in DMH group as compared with controls and treatment groups. In immunohistochemical evaluations, there was an increase in intensity and extent of staining of MMP-2 and MMP-9 in DMH group as compared to controls and treatment groups. The decrease in celecoxib group was more prominent. Overall, it was concluded that NSAIDs, particularly cyclooxygenase-2 (COX-2) inhibitors, might have a protective effect on CRC development and slow down progression of tumor in a DMH-induced experimental cancer model. One of the possible mechanisms in the chemoprevention of colon cancer seems to be inhibition of angiogenesis by diclofenac and celecoxib.

Multi-scale mechanical characterization of prostate cancer cell lines: Relevant biological markers to evaluate the cell metastatic potential

BACKGROUND

Considering the importance of cellular mechanics in the birth and evolution of cancer towards increasingly aggressive stages, we compared nano-mechanical properties of non-tumoral (WPMY-1) and highly aggressive metastatic (PC-3) prostate cell lines both on cell aggregates, single cells, and membrane lipids.

METHODS

Cell aggregate rheological properties were analyzed during dynamic compression stress performed on a homemade rheometer. Single cell visco-elasticity measurements were performed by Atomic Force Microscopy using a cantilever with round tip on surface-attached cells. At a molecular level, the lateral diffusion coefficient of total extracted lipids deposited as a Langmuir monolayer on an air-water interface was measured by the FRAP technique.

RESULTS

At cellular pellet scale, and at single cell scale, PC-3 cells were less stiff, less viscous, and thus more prone to deformation than the WPMY-1 control. Interestingly, stress-relaxation curves indicated a two-step response, which we attributed to a differential response coming from two cell elements, successively stressed. Both responses are faster for PC-3 cells. At a molecular scale, the dynamics of the PC-3 lipid extracts are also faster than that of WPMY-1 lipid extracts.

CONCLUSIONS

As the evolution of cancer towards increasingly aggressive stages is accompanied by alterations both in membrane composition and in cytoskeleton dynamical properties, we attribute differences in viscoelasticity between PC-3 and WPMY-1 cells to modifications of both elements.

GENERAL SIGNIFICANCE

A decrease in stiffness and a less viscous behavior may be one of the diverse mechanisms that cancer cells adopt to cope with the various physiological conditions that they encounter.

CoQ10 selective miscibility and penetration into lipid monolayers with lower lateral packing density

CoQ₁₀ is ubiquitously present in eukaryotic cells. It acts as electron carrier in the electron transport chain of the inner membrane of the mitochondria to facilitate aerobic cellular respiration. A highly stable lipid nanodispersion formulation containing CoQ₁₀ (BPM31510) is currently in clinical investigation for treatment of cancer. This study was designed to determine whether biophysical interactions between CoQ₁₀ and lipid, in part, explain the observed stability and cellular accumulation of CoQ₁₀ in cells and tissues. A lipid monolayer at the air-water interface was used as an experimental membrane model to measure CoQ₁₀ penetration and solubility. Lipid monolayers with varying proportions of CoQ₁₀ were laterally compressed to measure CoQ₁₀ miscibility and lateral organization. Additionally, lipid monolayers with varying lateral packing densities were spread at the air-water interface and CoQ₁₀ was injected in proximity to measure its rate of penetration. Our results demonstrate that CoQ₁₀ selectively penetrates into lipid monolayers with a lower lateral packing density, and is excluded by monolayers of higher packing densities. Data also indicates that CoQ₁₀-lipid mixing is non-ideal. CoQ₁₀ presence in lipid monolayers is biphasic, with one phase occupying the interstitial space between the DMPC lipids, and the other phase is present as pure CoQ₁₀ domains. This work provides further insight into mechanism of action of CoQ₁₀ based formulations that can significantly increase intracellular CoQ₁₀ concentration to show pleotropic effects on cellular functions.

Non steroidal anti-inflammatory drugs modulate the physicochemical properties of plasma membrane in experimental colorectal cancer: a fluorescence spectroscopic study

According to "fluid-mosaic model," plasma membrane is a bilayer constituted by phospholipids which regulates the various cellular activities governed by many proteins and enzymes. Any chemical, biochemical, or physical factor has to interact with the bilayer in order to regulate the cellular metabolism where various physicochemical properties of membrane, i.e., polarization, fluidity, electrostatic potential, and phase state may get affected. In this study, we have observed the in vivo effects of a pro-carcinogen 1,2-dimethylhydrazine dihydrochloride (DMH) and the two non steroidal anti-inflammatory drugs (NSAIDs); sulindac and celecoxib on various properties of the plasma membrane of colonocytes, i.e., electric potential, fluidity, anisotropy, microviscosity, lateral diffusion, and phase state in the experimentally induced colorectal cancer. A number of fluorescence probes were utilized like membrane fluidity and anisotropy by 1,6-diphenyl-1,3,5-hexatriene, membrane microviscosity by Pyrene, membrane electric potential by merocyanine 540, lateral diffusion by N-NBD-PE, and phase state by Laurdan. It is observed that membrane phospholipids are less densely packed and therefore, the membrane is more fluid in case of carcinogenesis produced by DMH than control. But NSAIDs are effective in reverting back the membrane toward normal state when co-administered with DMH. The membrane becomes less fluid, composed of low electric potential phospholipids whose lateral diffusion is being prohibited and the membrane stays mostly in relative gel phase. It may be stated that sulindac and celecoxib, the two NSAIDs may exert their anti-neoplastic role in colorectal cancer via modifying the physicochemical properties of the membranes.

Diclofenac, a selective COX-2 inhibitor, inhibits DMH-induced colon tumorigenesis through suppression of MCP-1, MIP-1α and VEGF

Angiogenesis is a physiological process involving growth of new blood vessels from pre-existing ones; however, it also plays a critical role in tumor progression. It favors the transition from hyperplasia to neoplasia, that is, from a state of cellular multiplication to uncontrolled proliferation. Therefore targeting angiogenesis will be profitable as a mechanism to inhibit tumor's lifeline. Further, it is important to understand the cross-communication between vascular endothelial growth factor (VEGF)-master switch in angiogenesis and other molecules in the neoplastic and pro-inflammatory milieu. We studied the role of two important chemokines [monocyte chemoattractant protein (MCP)-1 and macrophage inflammatory protein (MIP)-lα] alongwith VEGF and matrix metalloproteinases (MMPs) in non-steroidal anti-inflammatory drugs (NSAIDs)-induced chemopreventive effect in experimental colon cancer in rat. 1,2-Dimethylhydrazine (DMH, 30 mg/kg body weight, subcutaneously (s.c.) once-a-week) for 18 wk was used as pro-carcinogen and diclofenac (8 mg/kg body weight, orally daily) as the preferential cyclooxygenase-2 (COX-2) inhibitor. Expression of COX-2 and VEGF was found to be significantly elevated in the DMH-treated group as compared to the control, which was lowered notably by Diclofenac co-administration with DMH. Gelatin zymography showed prominent MMP-9 activity in the DMH-treated rats, while the activity was nearly absent in all the other groups. Expression of MCP-1 was found to be markedly increased whereas MIP-1α expression was found to be decreased in colonic mucosa from DMH-treated rats, which was reversed in the DMH + Diclofenac group. Our results indicate potential role of chemokines alongwith VEGF in angiogenesis in DMH-induced cancer and its chemoprevention with diclofenac.