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PDF file - 99K, Supplementary Table S3. Fold gene expression in the OFB as a result of age or parity. Normalized gene expression (to L19) is expressed as fold gene expression change compared young adult nulliparous mice (yNP). Mature adult nulliparous mice (aNP); mature adult parous mice (aP). *: p

PDF file - 76K, Supplementary Table S2. Cancer-associated immune cell changes in the peritoneal serous fluid (PSF). PSFs from young adult nulliparous mice (yNP) and mature adult parous mice (aP) that were either implanted with MOSE-LFFLv cells or administered PBS (na�ve) were harvested at 3 weeks post-implantation by peritoneal lavage. Immune cell subsets were identified by cell surface marker expression using FACS analysis and are presented as a percentage of total CD45+ cells

PDF file - 73K, Supplementary Table S1. Comparison of the age- and parity-associated immune cell changes in the PSF in the homeostatic state. PSFs from na�ve young adult nulliparous mice (yNP), mature adult nulliparous (aNP) and mature adult parous mice (aP) were harvested by peritoneal lavage. Immune cell subsets were identified by cell surface marker expression using FACS analysis and are presented as a percentage of total CD45+ cells.

PDF file - 101K, Supplementary Table S4. Fold gene expression change in the OFB as a consequence of MOSE-LFFLv implantation. Normalized gene expression (to L19) is expressed as fold gene expression change compared to non-cancer bearing matched animals (PBS). Young adult nulliparous mice (yNP); mature adult parous mice (aP). *: p

Cell separation has become a critical diagnostic, research, and treatment tool for personalized medicine. Despite significant advances in cell separation, most widely used applications require the use of multiple, expensive antibodies to known markers in order to identify subpopulations of cells for separation. Dielectrophoresis (DEP) provides a biophysical separation technique that can target cell subpopulations based on phenotype without labels and return native cells for downstream analysis. One challenge in employing any DEP device is the sample being separated must be transferred into an ultra-low conductivity medium, which can be detrimental in retaining cells' native phenotypes for separation. Here, we measured properties of traditional DEP reagents and determined that after just 1-2 hours of exposure and subsequent culture, cells' viability was significantly reduced below 50%. We developed and tested a novel buffer (Cyto Buffer) that achieved 6 weeks of stable shelf life and demonstrated significantly improved viability and physiological properties. We then determined the impact of Cyto Buffer on cells' dielectric properties and morphology and found that cells retained properties more similar to that of their native media. Finally, we vetted Cyto Buffer's usability on a cell separation platform (Cyto R1) to determine combined efficacy for cell separations. Here, more than 80% of cells from different cell lines were recovered and were determined to be >70% viable following exposure to Cyto Buffer, flow stimulation, electromanipulation, and downstream collection and growth. The developed buffer demonstrated improved opportunities for electrical cell manipulation, enrichment, and recovery for next generation cell separations. This article is protected by copyright. All rights reserved.

The trapping and deflection of biological cells by dielectrophoresis (DEP) at field non-uniformities in a microfluidic device is often conducted in a contactless dielectrophoresis (cDEP) mode, wherein the electrode channel is in a different layer than the sample channel, so that field penetration through the interceding barrier causes DEP above critical cut-off frequencies. In this manner, through physical separation of the electrode and sample channels, it is possible to spatially modulate electric fields with no electrode-induced damage to biological cells in the sample channel. However, since this device requires interlayer alignment of the electrode to sample channel and needs to maintain a thin interceding barrier (~ 15 μm) over the entire length over which DEP is needed (~ 1 cm), variations in alignment and microstructure fidelity cause wide variations in cDEP trapping level and frequency response across devices. We present a strategy to eliminate interlayer alignment by fabricating self-aligned electrode and sample channels, simultaneously with the interceding barrier layer (14-μm width and 50-μm depth), using a single-layer imprint and bond process on cyclic olefin copolymer. Specifically, by designing support structures, we preserve fidelity of the high aspect ratio insulating posts in the sample channel and the interceding barrier between the sample and electrode channels over the entire device footprint (~ 1 cm). The device operation is validated based on impedance measurements to quantify field penetration through the interceding barrier and by DEP trapping measurements. The presented fabrication strategy can eventually improve cDEP device manufacturing protocols to enable more reproducible DEP performance. Graphical abstract.

Ovarian cancer is routinely diagnosed long after the disease has metastasized through the fibrous sub-mesothelium. Despite extensive research in the field linking ovarian cancer progression to increasingly poor prognosis, there are currently no validated cellular markers or hallmarks of ovarian cancer that can predict metastatic potential. To discern disease progression across a syngeneic mouse ovarian cancer progression model, here, we fabricated extracellular-matrix mimicking suspended fiber networks: crosshatches of mismatch diameters for studying protrusion dynamics, aligned same diameter networks of varying inter-fiber spacing for studying migration, and aligned nanonets for measuring cell forces. We found that migration correlated with disease, while force-disease biphasic relationship exhibited f-actin stress-fiber network dependence. However, unique to suspended fibers, coiling occurring at tips of protrusions and not the length or breadth of protrusions displayed strongest correlation with metastatic potential. To confirm that our findings were more broadly applicable beyond the mouse model, we repeated our studies in human ovarian cancer cell lines and found that the biophysical trends were consistent with our mouse model results. Altogether, we report complementary high throughput and high content biophysical metrics capable of identifying ovarian cancer metastatic potential on time scale of hours. Published version

Single-cell level investigations such as DNA and RNA sequencing, protein analyses, and phenotypic studies require an input sample with a high rate of viability (>90%). If too many dead cells are present in the input, degraded proteins and ambient DNA or RNA can increase background noise that may lead to missing identification of crucial targets. Since the cost for single-cell sequencing experiments still remains high, it is critical to ensure the input sample is optimized for high viability to ensure cost-effective and reproducible data. Current bead assays or other sample viability enrichment techniques used in preparation for single-cell analyses typically result in a significant sample loss, sometimes sacrificing 80% of the starting sample, and these preparation steps require multiple passes (> 45 minutes time) and costly kits. These beads or kits can be biased and change the cell population, subject cells to unwanted stresses, and diminish sample integrity with the time needed for preparations. Here, we investigate sample cell viability enrichment on the Cyto R1 Platform, a label-free, cell enrichment, sorting, and recovery platform. At the core, the Cyto R1 uses Cyto Chips, microfluidic technologies with electrical fields, to phenotypically enrich and sort various cells based upon cells’ unique physical structures and subcellular features. Thus, the Cyto R1 ensures native cell recovery without any unwanted cell tagging to maximize sample integrity. In this work, a variety of single cell solutions derived from T cell lymphoma tumors, ascites fluid, and organ tissues were enriched for viable cells to obtain a final sample viability over 90%. Additionally, we aimed to achieve a minimum of 50,000 viable cells, a common target for single-cell sequencing, in as rapid a timeframe as possible. In one sample origin tested, murine T cell lymphomas, the average starting viability was 65 ± 6.5%, and the final viability after enrichment on the Cyto R1 Platform was 95.8 ± 1.8%. Similarly, murine ascites cell mixtures were enriched from average viabilities below 55% up to 91.6 ± 4.2%. For all samples tested, >50,000 viable cells were obtained in under 30 minutes. This work demonstrates that the Cyto R1 can effectively and efficiently enrich a variety of starting samples for high viability (>90%) as required for downstream assays and single-cell sequencing. Citation Format: Alexandra R. Hyler, Alicia M. Cole, Ridi Barua, Amiran K. Dzutsev, Eva M. Schmelz. Cyto R1 Platform enriches samples’ viability for single-cell sequencing and downstream assays [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 1687.

Ovarian cancer remains a deadly disease and its recurrence disease is due in part to the presence of disseminating ovarian cancer aggregates not removed by debulking surgery. During dissemination in a dynamic ascitic environment, the spheroid cells’ metabolism is characterized by low respiration and fragmented mitochondria, a metabolic phenotype that may not support secondary outgrowth after adhesion. Here, we investigated how adhesion affects cellular respiration and substrate utilization of spheroids mimicking early stages of secondary metastasis. Using different glucose and oxygen levels, we investigated cellular metabolism at early time points of adherence (24 h and less) comparing slow and fast-developing disease models. We found that adhesion over time showed changes in cellular energy metabolism and substrate utilization, with a switch in the utilization of mostly glutamine to glucose but no changes in fatty acid oxidation. Interestingly, low glucose levels had less of an impact on cellular metabolism than hypoxia. A resilience to culture conditions and the capacity to utilize a broader spectrum of substrates more efficiently distinguished the highly aggressive cells from the cells representing slow-developing disease, suggesting a flexible metabolism contributes to the stem-like properties. These results indicate that adhesion to secondary sites initiates a metabolic switch in the oxidation of substrates that could support outgrowth and successful metastasis. Published version

Nanosecond pulsed electric fields (nsPEFs) may induce differential effects on tumor cells from different disease stages and could be suitable for treating tumors by preferentially targeting the late-stage/highly aggressive tumor cells. In this study, we investigated the nsPEF responses of mouse ovarian surface epithelial (MOSE) cells representing progressive ovarian cancer from benign to malignant stages and highly aggressive tumor-initiating-like cells. We established the cell-seeded 3D collagen scaffolds cultured with or without Nocodazole (eliminating the influence of cell proliferation on ablation outcome) to observe the ablation effects at 3h and 24h after treatment and compared the corresponding thresholds obtained by numerically calculated electric field distribution. The results showed that nsPEFs induced larger ablation areas with lower thresholds as the cell progress from benign, malignant to a highly aggressive phenotype. This differential effect was not affected by the different doubling times of the cells, as apparent by similar ablation induction after a synergistic treatment of nsPEFs and Nocodazole. The result suggests that nsPEFs could induce preferential ablation effects on highly aggressive and malignant ovarian cancer cells than their benign counterparts. This study provides an experimental basis for the research on killing malignant tumor cells via electrical treatments and may have clinical implications for treating tumors and preventing tumor recurrence after treatment. Index Terms: Nanosecond pulses, ovarian cancer progression model, cellular ablation, selectivity, electroporation.

A common problem with cancer treatment is the development of treatment resistance and tumor recurrence that result from treatments that kill most tumor cells yet leave behind aggressive cells to repopulate. Presented here is a microfluidic device that can be used to isolate tumor subpopulations to optimize treatment selection. Dielectrophoresis (DEP) is a phenomenon where particles are polarized by an electric field and move along the electric field gradient. Different cell subpopulations have different DEP responses depending on their bioelectrical phenotype, which, we hypothesize, correlate with aggressiveness. We have designed a microfluidic device in which a region containing posts locally distorts channel of the electric field created by an AC voltage across a microfluidic channel and which forces cells toward the posts through DEP. This force is balanced with a simultaneous drag force from fluid motion that pulls cells away from the posts. We have shown that by adjusting the drag force, cells with aggressive phenotypes are influenced more by the DEP force and trap on posts while others flow through the chip unaffected. Utilizing single-cell trapping on cell-sized posts by a drag-DEP force balance, we show that separation of very similar cell subpopulations may be achieved, a result that was previously impossible with DEP alone. Separated subpopulations maintain high viability downstream, and remain in a native state, without fluorescent labeling. These cells can then be cultured to help select a therapy that kills aggressive subpopulations equally or better than the bulk of the tumor, mitigating resistance and recurrence. This article is protected by copyright. All rights reserved

Background: This study presents a label-free method of separating macrophages and fibroblasts, cell types critically associated with tumors. Materials and Methods: Contactless dielectrophoresis (DEP) devices were used to separate fibroblasts from macrophages by selectively trapping one population. An ImageJ macro was developed to determine the percentage of each population moving or stationary at a given point in time in a video. Results: At 350V(rms), 20 kHz, and 1.25 μL/min, more than 90% of fibroblasts were trapped while less than 20% of macrophages were trapped. Conclusions: Contactless DEP was used to study macrophage and fibroblast separation as a proof-of-concept study for separating cells in the tumor microenvironment. The associated ImageJ macro could be used in other microfluidic cell separation studies.

Ovarian cancer is the deadliest gynecological cancer in women, with a survival rate of less than 30% when the cancer has spread throughout the peritoneal cavity. Aggregation of cancer cells increases their viability and metastatic potential; however, there are limited studies that correlate these functional changes to specific phenotypic alterations. In this study, we investigated how changes in media composition affects the metastatic potential of ovarian cancer cells. This was conducted by using aggregated ovarian cancer cells incubated in different media conditions supplemented with different levels of glucose, glutamine and serum. Additionally, we identified the adherence capacity through examining secretions and expression of extracellular matrix proteins as well as mitochondrial localization and quality control protein content that could support the viability of these aggregates. We determined that spheroid formation requires more glutamine and limited serum and glucose to allow for successful aggregation. Additionally, this media composition supports a more proliferative phenotype that closely resembles the high glucose controls. Low glucose and hypoxia also limit the ability of spheroids to adhere due to limited expression and secretion of collagen type I and fibronectin proteins. Further, we find that mitochondrial localization is promptly more affiliated with the adherence site of spheroids incubated in high glucose, high oxygen media in comparison to low glucose, hypoxic spheroids where mitochondrial localization is heavily dispersed. Finally, we find that mitophagy and mitobiogenesis are codependent in regulating mitochondrial content to support viability in cancer spheroids in peritoneal media conditions. Altogether, these data indicate that ovarian cancer spheroids adapt to non-permissive conditions through limiting their adherence capacity and upregulating mitochondrial quality control functions to support viability during dissemination. Citation Format: Joseph Grieco, Stephanie Edwards Compton, James Smyth, Eva Schmelz. Dysregulated metastatic capacity of ovarian cancer spheroids in response to physiologically relevant media conditions [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 2932.

Ovarian cancer is typically diagnosed at late stages with a poor prognosis due to high recurrence. Exfoliation from the primary tumor results in aggregation of ovarian cancer cells into spheroids in the peritoneal cavity, which then adhere to secondary sites to form metastatic outgrowth. Spheroids in the peritoneal cavity are exposed to hypoxic, low glucose conditions. Sphingosine-1-phosphate (S1P), increased in the ascites fluid of ovarian cancer patients, has been shown to increase tumor cell survival and tumorigenesis through changes in mitochondrial function. However, little is known about these effects in ovarian cancer spheroids, particularly upon secondary adherence and outgrowth in physiological conditions. Changes in spheroid metabolism in response to treatment with S1P, hypoxia, low glucose, and obese peritoneal serous fluid (PSF) in both free and adherent states was investigated. Using a late-stage and tumor-initiating murine ovarian cancer model, spheroids were subjected to treatment with S1P or obese PSF as free or adherent spheroids. Using a Seahorse XFe96, we investigated changes in metabolism over time trials measured after 24 hour treatment for free spheroids and after different time points of adherence (4, 8, 12, and 24 hours). Data show changes in basal respiration, maximal oxygen consumption rate, and spare respiratory capacity of spheroids over adherence time when treated with S1P and PSF. This suggests that the cells respond to energetic demand with metabolic flexibility as the spheroids adhere to new surfaces. The identification of the regulation of these events may help elucidate the flexibility that takes place during metastasis in culture that more closely mimics physiological conditions, providing a foundation for future interventions for preventative therapies for ovarian cancer with dietary sphingolipids and possible treatment targets. Citation Format: Stephanie Edwards Compton, Joseph Grieco, Eva M. Schmelz. Metabolic plasticity of ovarian metastases in response to adherence and physiologically relevant culture conditions [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 2405.

Long‐term survival rates for advanced ovarian cancer patients have not changed appreciably over the past four decades; therefore, development of new, effective treatment modalities remains a high priority. Tumor Treating Fields (TTFields), a clinically active anticancer modality utilize low‐intensity, intermediate frequency, alternating electric fields. The goal of this study was to evaluate the efficacy of combining TTFields with paclitaxel against ovarian cancer cells in vitro and in vivo. In vitro application of TTFields on human ovarian cancer cell lines led to a significant reduction in cell counts as compared to untreated cells. The effect was found to be frequency and intensity dependent. Further reduction in the number of viable cells was achieved when TTFields treatment was combined with paclitaxel. The in vivo effect of the combined treatment was tested in mice orthotopically implanted with MOSE‐LTICv cells. In this model, combined treatment led to a significant reduction in tumor luminescence and in tumor weight as compared to untreated mice. The feasibility of effective local delivery of TTFields to the human abdomen was examined using finite element mesh simulations performed using the Sim4life software. These simulations demonstrated that electric fields intensities inside and in the vicinity of the ovaries of a realistic human computational phantom are about 1 and 2 V/cm pk‐pk, respectively, which is within the range of intensities required for TTFields effect. These results suggest that prospective clinical investigation of the combination of TTFields and paclitaxel is warranted., What's new? Tumor Treating Fields (TTFields), in which tumor cell division is disrupted by exposure to alternating electric fields, are a promising therapeutic strategy against cancer. In this study, TTFields are shown to enhance the efficacy of paclitaxel in ovarian cancer, both in vitro and in vivo. The feasibility of effectively delivering TTFields across a large nonuniform volume, encompassing ovaries and potential metastatic sites, is demonstrated via electric field measurements in mice and through finite‐element mesh simulations. The results have given impetus to an open‐label pilot investigation of TTFields administered in combination with paclitaxel in patients with recurrent ovarian cancer.

Ovarian metastases exfoliate from the primary tumor and it is thought that aggregation supports their survival in the peritoneal cavity during dissemination but the underlying mechanisms are not clearly identified. We have previously shown that ovarian cancer cells acquire an increasingly glycolytic and metabolic flexible phenotype during progression. In the present study, we investigated how hypoxia, aggregation, and the incorporation of the obese stromal vascular fraction (SVF) affect cellular metabolism and the response to common anti-cancer and anti-diabetic drugs. Our results show a reduction of glucose uptake, lactate secretion, cellular respiration and ATP synthesis in response to hypoxia and aggregation, suggesting that the observed reduced proliferation of cells aggregated into spheroids is the result of a down-regulation of respiration. Recruitment of SVF to spheroids increased the spheroids invasive capacity but reduced respiration only in the most aggressive cells. Further, aggregation and hypoxia reduced the response to the metabolic drugs AICAR and metformin, and the chemotherapeutic agents cisplatin and paclitaxel. Our results suggest that the adaptation of cellular metabolism may contribute to enhanced survival under non-permissive conditions, and that these metabolic alterations may provide targets for future interventions that aim to enhance the survival of women with metastatic ovarian cancer.

Bioactive dietary agents (i.e., nutraceuticals) have shown the ability to slow or eliminate cancer growth with marked immediate effects when applied directly to cancer cells. By isolation and inspection of the effective components in these therapeutic agents, with respect to cancer cell inhibition, a clear mechanism of action can contribute to a better understanding of the benefits of these natural products. Here we have examined the effects of three essential oil formulations of nutraceutical agents: Frankincense, Garlic and Cinnamon, and ultimately investigated trans-cinnamaldehyde (TC), the active ingredient in cinnamon oil and a documented anti-inflammatory and anti-cancer agent, on cell viability and migratory potential in in vitro models of breast cancer representing different tumorigenic and metastatic potential. Results show that TC exhibits a clear dose-response relationship in inhibiting cancer cell survival and migration in a breast cancer aggression-dependent manner. Our results suggest that TC may be a promising candidate for the development of effective strategies to counter breast cancer in vivo by reducing or eliminating its progression.

The identification and separation of cells from heterogeneous populations is critical to the diagnosis of diseases. Label-free methodologies in particular have been developed to manipulate individual cells using properties such as density and morphology. The electrical properties of malignant cells, including the membrane capacitance and cytoplasmic conductivity, have been demonstrated to be altered compared to non-malignant cells of similar origin. Here, we exploit these changes to characterize individual cells in a sequentially-staged in vitro cancer model using electrorotation (EROT)—the rotation of a cell induced by a rotating electric field. Using a microfabricated device, a dielectrophoretic force to suspend cells while measuring their angular velocity resulting from an EROT force applied at frequencies between 3 kHz to 10 MHz. We experimentally determine the EROT response for cells at three stages of malignancy and analyze the resultant spectra by considering models that include the effect of the cell membrane alone (single-shell model) and the combined effect of the cell membrane and nucleus (double-shell model). We find that the cell membrane is largely responsible for a given cell’s EROT response between 3 kHz and 10 MHz. Our results also indicate that membrane capacitance, membrane conductance, and cytoplasmic conductivity increase with an increasingly malignant phenotype. Our results demonstrate the potential of using electrorotation as a means making of non-invasive measurements to characterize the dielectric properties of cancer cells. The authors would like to acknowledge the generous financial support provided by the LabeX LaSIPS (ANR-10-LABX-0040-LaSIPS) managed by the French National Research Agency under the “Investissements d’avenir” program (nANR-11-IDEX-0003-02) and COST TD1104, www.electroporation.net. The authors would like to thank the NSF CAREER Award CBET-1055913, the NSF IGERT DGE-09661, and the NIH R01- CA213423 for their gracious support of this work. The authors would also like to acknowledge project support from ENS Paris Saclay and Virginia Tech.

Ovarian cancer cells are exposed to physical stress in the peritoneal cavity during both tumor growth and dissemination. Ascites build-up in metastatic ovarian cancer further increases the exposure to fluid shear stress. Here, we used a murine, in vitro ovarian cancer progression model in parallel with immortalized human cells to investigate how ovarian cancer cells of increasing aggressiveness respond to [Formula: see text] of fluid-induced shear stress. This biophysical stimulus significantly reduced cell viability in all cells exposed, independent of disease stage. Fluid shear stress induced spheroid formation and altered cytoskeleton organization in more tumorigenic cell lines. While benign ovarian cells appeared to survive in higher numbers under the influence of fluid shear stress, they exhibited severe morphological changes and chromosomal instability. These results suggest that exposure of benign cells to low magnitude fluid shear stress can induce phenotypic changes that are associated with transformation and ovarian cancer progression. Moreover, exposure of tumorigenic cells to fluid shear stress enhanced anchorage-independent survival, suggesting a role in promoting invasion and metastasis.

The omental fat band (OFB) is the predominant site for metastatic seeding of ovarian cancer. Previously, we highlighted the influx and accumulation of neutrophils and macrophages in the OFB following syngeneic ovarian cancer cell seeding as an important factor in the development of a protumorigenic cascade. Here we investigated localized immunomodulation as a means of promoting a successful protective response. As an important TH1-type immunomodulator, interleukin (IL)-12 has previously been investigated clinically as an anticancer therapeutic. However, systemic IL-12 administration was associated with serious side effects, galvanizing the development of immune or accessory cells engineered to express secreted or membrane-bound IL-12 (mbIL-12). Using an mbIL-12-expressing cell variant, we demonstrate that localized IL-12 in the tumor microenvironment significantly delays disease development. The mbIL-12-mediated decrease in tumor burden was associated with a significant reduction in neutrophil and macrophage infiltration in the OFB, and correlated with a reduced expression of neutrophil and macrophage chemoattractants (CXCL1, -2, -3 and CCL2, -7). Vaccination with mitotically impaired tumor cells did not confer protection against subsequent tumor challenge, indicating that IL-12 did not impact the immunogenicity of the cancer cells. Our findings are in agreement with previous reports suggesting that IL-12 may hold promise when delivered in a targeted and sustained manner to the omental microenvironment. Furthermore, resident cells within the omental microenvironment may provide a reservoir that can be activated and mobilized to prevent metastatic seeding within the peritoneum and, therefore, may be targets for chemotherapeutics.

Overactive mitochondrial fission was shown to promote cell transformation and tumor growth. It remains elusive how mitochondrial quality is regulated in such conditions. Here, we show that upregulation of mitochondrial fission protein, dynamin related protein-1 (Drp1), was accompanied with increased mitochondrial biogenesis markers (PGC1α, NRF1, and Tfam) in breast cancer cells. However, mitochondrial number was reduced, which was associated with lower mitochondrial oxidative capacity in breast cancer cells. This contrast might be owing to enhanced mitochondrial turnover through autophagy, because an increased population of autophagic vacuoles engulfing mitochondria was observed in the cancer cells. Consistently, BNIP3 (a mitochondrial autophagy marker) and autophagic flux were significantly upregulated, indicative of augmented mitochondrial autophagy (mitophagy). The upregulation of Drp1 and BNIP3 was also observed in vivo (human breast carcinomas). Importantly, inhibition of Drp1 significantly suppressed mitochondrial autophagy, metabolic reprogramming, and cancer cell viability. Together, this study reveals coordinated increase of mitochondrial biogenesis and mitophagy in which Drp1 plays a central role regulating breast cancer cell metabolism and survival. Given the emerging evidence of PGC1αcontributing to tumor growth, it will be of critical importance to target both mitochondrial biogenesis and mitophagy for effective cancer therapeutics.

We explored the use of irreversible electroporation (IRE) and high-frequency irreversible electroporation (H-FIRE) to induce cell death of tumor-initiating cells using a mouse ovarian surface epithelial (MOSE) cancer model. Tumor-initiating cells (TICs) can be successfully destroyed using pulsed electric field parameters common to irreversible electroporation protocols. Additionally, high-frequency pulses seem to induce cell death of TICs at significantly lower electric fields suggesting H-FIRE can be used to selectively target TICs and malignant late-stage cells while sparing the non-malignant cells in the surrounding tissue. We evaluate the relationship between threshold for cell death from H-FIRE pulses and the capacitance of cells as well as other properties that may play a role on the differences in the response to conventional IRE versus H-FIRE treatment protocols.

Ovarian cancer cells are exposed to physical stress in the peritoneal cavity during both tumor growth and dissemination. Ascites build-up in metastatic ovarian cancer further increases the exposure to fluid shear stress. Here, we used a murine, in vitro ovarian cancer progression model in parallel with immortalized human cells to investigate how ovarian cancer cells of increasing aggressiveness respond to [Formula: see text] of fluid-induced shear stress. This biophysical stimulus significantly reduced cell viability in all cells exposed, independent of disease stage. Fluid shear stress induced spheroid formation and altered cytoskeleton organization in more tumorigenic cell lines. While benign ovarian cells appeared to survive in higher numbers under the influence of fluid shear stress, they exhibited severe morphological changes and chromosomal instability. These results suggest that exposure of benign cells to low magnitude fluid shear stress can induce phenotypic changes that are associated with transformation and ovarian cancer progression. Moreover, exposure of tumorigenic cells to fluid shear stress enhanced anchorage-independent survival, suggesting a role in promoting invasion and metastasis.

An altered metabolism during ovarian cancer progression allows for increased macromolecular synthesis and unrestrained growth. However, the metabolic phenotype of cancer stem or tumor-initiating cells, small tumor cell populations that are able to recapitulate the original tumor, has not been well characterized. In the present study, we compared the metabolic phenotype of the stem cell enriched cell variant, MOSE-LFFLv (TIC), derived from mouse ovarian surface epithelial (MOSE) cells, to their parental (MOSE-L) and benign precursor (MOSE-E) cells. TICs exhibit a decrease in glucose and fatty acid oxidation with a concomitant increase in lactate secretion. In contrast to MOSE-L cells, TICs can increase their rate of glycolysis to overcome the inhibition of ATP synthase by oligomycin and can increase their oxygen consumption rate to maintain proton motive force when uncoupled, similar to the benign MOSE-E cells. TICs have an increased survival rate under limiting conditions as well as an increased survival rate when treated with AICAR, but exhibit a higher sensitivity to metformin than MOSE-E and MOSE-L cells. Together, our data show that TICs have a distinct metabolic profile that may render them flexible to adapt to the specific conditions of their microenvironment. By better understanding their metabolic phenotype and external environmental conditions that support their survival, treatment interventions can be designed to extend current therapy regimens to eradicate TICs.

We herein report, for the first time, the mechanical properties of ovarian cancer stem-like/tumor-initiating cells (CSC/TICs). The represented model is a spontaneously transformed murine ovarian surface epithelial (MOSE) cell line that mimics the progression of ovarian cancer from early/non-tumorigenic to late/highly aggressive cancer stages. Elastic modulus measurements via atomic force microscopy (AFM) illustrate that the enriched CSC/TICs population (0.32±0.12kPa) are 46%, 61%, and 72% softer (P0.0001) than their aggressive late-stage, intermediate, and non-malignant early-stage cancer cells, respectively. Exposure to sphingosine, an anti-cancer agent, induced an increase in the elastic moduli of CSC/TICs by more than 46% (0.47±0.14kPa, P0.0001). Altogether, our data demonstrate that the elastic modulus profile of CSC/TICs is unique and responsive to anti-cancer treatment strategies that impact the cytoskeleton architecture of cells. These findings increase the chance for obtaining distinctive cell biomechanical profiles with the intent of providing a means for effective cancer detection and treatment control.This novel study utilized atomic force microscopy to demonstrate that the elastic modulus profile of cancer stem cell-like tumor initiating cells is unique and responsive to anti-cancer treatment strategies that impact the cytoskeleton of these cells. These findings pave the way to the development of unique means for effective cancer detection and treatment control.

Ovarian cancer is typically diagnosed at late stages with a poor prognosis due to high recurrence. Exfoliation from the primary tumor results in aggregation of ovarian cancer cells into spheroids in the peritoneal cavity, which may increase survival of cancer and metastasis to other tissues. We have previously reported metabolic changes in adherent ovarian cancer cells to rely more heavily on glycolysis. However, metabolic changes in cancer cell aggregates are poorly understood. In this study, we investigated differences in spheroid metabolism in normoxic and hypoxic conditions as compared to adherent cells. We examined late-stage and tumor-initiating murine ovarian cancer monolayers and spheroids. Using a Seahorse XF extracellular flux analyzer, we investigated changes in metabolism over time in the presence of mitochondrial inhibitors (oligomycin and rotenone) or uncouplers (FCCP). Data show a reduction in basal respiration, maximal oxygen consumption rate, and spare respiratory capacity of spheroids compared to adherent monolayers. This suggests a reduction in energetic demand and metabolic flexibility in spheroids, which may confer increased survival capabilities. The identification of these metabolic changes that may increase survival and metastasis of spheroids provide targets for treatment to control the ability of spheroids to survive in the peritoneal cavity. Citation Format: Stephanie Edwards, Emily Pyne, Lu Lui, Jack Guinan, Madlyn Frisard, Eva Schmelz. Aggregation alters the metabolism of serous ovarian cancer cells [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 808.

Ovarian cancer is a multigenic disease and molecular events driving ovarian cancer progression are not well established. We have previously reported the dysregulation of the cytoskeleton during ovarian cancer progression in a syngeneic mouse cell model for progressive ovarian cancer. In the present studies, we investigated if the cytoskeleton organization is a potential target for chemopreventive treatment with the bioactive sphingolipid metabolite sphingosine. Long-term treatment with non-toxic concentrations of sphingosine but not other sphingolipid metabolites led to a partial reversal of a cytoskeleton architecture commonly associated with aggressive cancer phenotypes towards an organization reminiscent of non-malignant cell phenotypes. This was evident by increased F-actin polymerization and organization, a reduced focal adhesion kinase expression, increased a-actinin and vinculin levels which together led to the assembly of more mature focal adhesions. Downstream focal adhesion signaling, the suppression of myosin light chain kinase expression and hypophosphorylation of its targets were observed after treatment with sphingosine. These results suggest that sphingosine modulate the assembly of actin stress fibers via regulation of focal adhesions and myosin light chain kinase. The impact of these events on suppression of ovarian cancer by exogenous sphingosine and their potential as molecular markers for treatment efficacy warrants further investigation.

It is well documented that the tumor microenvironment profoundly impacts the etiology and progression of breast cancer, yet the contribution of the resident microbiome within breast tissue remains poorly understood. Tumor microenvironmental conditions, such as hypoxia and dense tumor stroma, predispose progressive phenotypes and therapy resistance, however the role of bacteria in this interplay remains uncharacterized. We hypothesized that the effect of individual bacterial secreted molecules on breast cancer viability and proliferation would be modulated by these tumor-relevant stressors differentially for cells at varying stages of progression. To test this, we incubated human breast adenocarcinoma cells (MDA-MB-231,MCF-DCIS.com) and non-malignant breast epithelial cells (MCF-10A) with N-(3-oxododecanoyl)-L-homoserine lactone (OdDHL), a quorum-sensing molecule fromPseudomonas aeruginosathat regulates bacterial stress responses. This molecule was selected becausePseudomonaswas recently characterized as a significant fraction of the breast tissue microbiome and OdDHL is documented to impact mammalian cell viability. After OdDHL treatment, we demonstrated the greatest decrease in viability with the more malignant MDAMB-231 cells and an intermediateMCF-DCIS.com(ductal carcinomain situ) response. The responses were also culture condition (i.e. microenvironment) dependent. These results contrast the MCF-10A response, which demonstrated no change in viability in any culture condition. We further determined that the observed trends in breast cancer viability were due to modulation of proliferation for both cell types, as well as the induction of necrosis for MDA-MB-231 cells in all conditions. Our results provide evidence that bacterial quorum-sensing molecules interact with the host tissue environment to modulate breast cancer viability and proliferation, and that the effect of OdDHL is dependent on both cell type as well as microenvironment. Understanding the interactions between bacterial signaling molecules and the host tissue environment will allow for future studies that determine the contribution of bacteria to the onset, progression, and therapy response of breast cancer.

It is well documented that the tumor microenvironment profoundly impacts the etiology and progression of breast cancer, yet the contribution of the resident microbiome within breast tissue remains poorly understood. Tumor microenvironmental conditions, such as hypoxia and dense tumor stroma, predispose progressive phenotypes and therapy resistance, however the role of bacteria in this interplay remains uncharacterized. We hypothesized that the effect of individual bacterial secreted molecules on breast cancer viability and proliferation would be modulated by these tumor-relevant stressors differentially for cells at varying stages of progression. To test this, we incubated human breast adenocarcinoma cells (MDA-MB-231, MCF-DCIS.com) and non-malignant breast epithelial cells (MCF-10A) with N-(3-oxododecanoyl)-L-homoserine lactone (OdDHL), a quorum-sensing molecule from Pseudomonas aeruginosa that regulates bacterial stress responses. This molecule was selected because Pseudomonas was recently characterized as a significant fraction of the breast tissue microbiome and OdDHL is documented to impact mammalian cell viability. After OdDHL treatment, we demonstrated the greatest decrease in viability with the more malignant MDA-MB-231 cells and an intermediate MCF-DCIS.com (ductal carcinoma in situ) response. The responses were also culture condition (i.e. microenvironment) dependent. These results contrast the MCF-10A response, which demonstrated no change in viability in any culture condition. We further determined that the observed trends in breast cancer viability were due to modulation of proliferation for both cell types, as well as the induction of necrosis for MDA-MB-231 cells in all conditions. Our results provide evidence that bacterial quorum-sensing molecules interact with the host tissue environment to modulate breast cancer viability and proliferation, and that the effect of OdDHL is dependent on both cell type as well as microenvironment. Understanding the interactions between bacterial signaling molecules and the host tissue environment will allow for future studies that determine the contribution of bacteria to the onset, progression, and therapy response of breast cancer.

Alterations in the biomechanical properties and cytoskeletal organization of cancer cells in addition to genetic changes have been correlated with their aggressive phenotype. In this study, we investigated changes in the viscoelasticity of mouse ovarian surface epithelial (MOSE) cells, a mouse model for progressive ovarian cancer. We demonstrate that the elasticity of late-stage MOSE cells (0.549 ± 0.281 kPa) were significantly less than that of their early-stage counterparts (1.097 ± 0.632 kPa). Apparent cell viscosity also decreased significantly from early (144.7 ± 102.4 Pa-s) to late stage (50.74 ± 29.72 Pa-s). This indicates that ovarian cells are stiffer and more viscous when they are benign. The increase in cell deformability directly correlates with the progression of a transformed phenotype from a nontumorigenic, benign cell to a tumorigenic, malignant one. The decrease in the level of actin in the cytoskeleton and its organization is directly associated with the changes in cell biomechanical property. From the Clinical Editor The authors have investigated changes in the viscoelasticity of mouse ovarian surface epithelial (MOSE) cells and demonstrated that ovarian cells are stiffer and more viscous when they are benign.

The use of non-invasive methods to detect and enrich circulating tumor cells (CTCs) independent of their genotype is critical for early diagnostic and treatment purposes. The key to using CTCs as predictive clinical biomarkers is their separation and enrichment. This work presents the use of a contactless dielectrophoresis (cDEP) device to investigate the frequency response of cells and calculate their area-specific membrane capacitance. This is the first demonstration of a cDEP device which is capable of operating between 10 and 100 kHz. Positive and negative dielectrophoretic responses were observed in red blood cells, macrophages, breast cancer, and leukemia cells. The area-specific membrane capacitances of MDA-MB231, THP-1 and PC1 cells were determined to be 0.01518 ± 0.0013, 0.01719 ± 0.0020, 0.01275 ± 0.0018 (F/m(2)), respectively. By first establishing the dielectrophoretic responses of cancerous cells within this cDEP device, conditions to detect and enrich tumor cells from mixtures with non-transformed cells can be determined providing further information to develop methods to isolate these rare cells.

This work is the first to demonstrate the ability of contactless dielectrophoresis (cDEP) to isolate target cell species from a heterogeneous sample of live cells. Since all cell types have a unique molecular composition, it is expected that their dielectrophoretic (DEP) properties are also unique. cDEP is a technique developed to improve upon traditional and insulator-based DEP devices by replacing embedded metal electrodes with fluid electrode channels positioned alongside desired trapping locations. Through the placement of the fluid electrode channels and the removal of contact between the electrodes and the sample fluid, cDEP mitigates issues associated with sample/electrode contact. MCF10A, MCF7, and MDA-MB-231 human breast cells were used to represent early, intermediate, and late-staged breast cancer, respectively. Trapping frequency responses of each cell type were distinct, with the largest difference between the cells found at 20 and 30 V. MDA-MB-231 cells were successfully isolated from a population containing MCF10A and MCF7 cells at 30 V and 164 kHz. The ability to selectively concentrate cells is the key to development of biological applications using DEP. The isolation of these cells could provide a workbench for clinicians to detect transformed cells at their earliest stage, screen drug therapies prior to patient treatment, increasing the probability of success, and eliminate unsuccessful treatment options.

Aging and DNA polymerase beta deficiency (beta-pol(+/-)) interact to accelerate the development of malignant lymphomas and adenocarcinoma and increase tumor bearing load in mice. Folate deficiency (FD) has been shown to induce DNA damage repaired via the base excision repair (BER) pathway. We anticipated that FD and BER deficiency would interact to accelerate aberrant crypt foci (ACF) formation and tumor development in beta-pol haploinsufficient animals. FD resulted in a significant increase in ACF formation in wild type (WT) animals exposed to 1,2-dimethylhydrazine, a known colon and liver carcinogen; however, FD reduced development of ACF in beta-pol haploinsufficient mice. Prolonged feeding of the FD diet resulted in advanced ACF formation and liver tumors in wild type mice. However, FD attenuated onset and progression of ACF and prevented liver tumorigenesis in beta-pol haploinsufficient mice, i.e. FD provided protection against tumorigenesis in a BER-deficient environment in all tissues where 1,2-dimethylhydrazine exerts its damage. Here we show a distinct down-regulation in DNA repair pathways, e.g. BER, nucleotide excision repair, and mismatch repair, and decline in cell proliferation, as well as an up-regulation in poly(ADP-ribose) polymerase, proapoptotic genes, and apoptosis in colons of FD beta-pol haploinsufficient mice.

Conjugated linoleic acid (CLA) exerts a protective effect on experimental inflammatory bowel disease and shows promise as a chemopreventive agent against colorectal cancer (CRC) in mice, although the mechanisms by which it exerts its beneficial effects against malignancies in the gut are not completely understood. Mice lacking PPARgamma in immune and epithelial cells and PPARgamma-expressing littermates were fed either control or CLA-supplemented (1 g CLA/100 g) diets to determine the role of PPARgamma in inflammation-induced CRC. To induce tumor formation and colitis, mice were treated with azoxymethane and then challenged with 2% dextran sodium sulfate, respectively. Dietary CLA ameliorated disease activity, decreased colitis, and prevented adenocarcinoma formation in the PPARgamma-expressing floxed mice but not in the tissue-specific PPARgamma-null mice. Dietary CLA supplementation significantly decreased the percentages of macrophages in the mesenteric lymph nodes (MLN) regardless of the genotype and increased regulatory T cell numbers in MLN of PPARgamma-expressing, but not in the tissue-specific, PPARgamma-null mice. Colonic tumor necrosis factor-alpha mRNA expression was significantly suppressed in CLA-fed, PPARgamma-expressing mice. This study suggests CLA ameliorates colitis and prevents tumor formation in part through a PPARgamma-dependent mechanism.

Sphingolipid metabolites are generated throughout the intestinal tract after hydrolysis of orally administered complex sphingolipids and significantly suppress colon cancer in carcinogen-treated CF1 mice. In the present study, the mechanisms of tumor suppression by dietary sphingolipids were investigated. Changes in select genes that are critical in early stages of colon cancer were analyzed in the colonic mucosa of dimethylhydrazine-treated CF1 mice fed AIN76A diet with or without 0.05% sphingomyelin. Supplementation with sphingomyelin did not significantly alter mRNA levels of most of the selected genes. However, a downregulation of ß-catenin (p=0.007) and increased protein levels of connexin-43 (p=0.017) and Bcl-2 (p=0.033) were observed in sphingomyelin-fed animals. This suggests that sphingolipids may be regulating specific post-transcriptional events to reverse aberrant expression of individual proteins. Since the dysregulation of ß-catenin metabolism and its transcriptional activity in addition to a decreased inter-cellular communication has been causally linked to the development of colon cancer while a low Bcl-2 expression is associated with a worse prognosis in colon cancer, the reversal of these early changes may be important events in the prevention of colon cancer by orally administered sphingolipids, and may provide specific molecular biomarkers for sphingolipid efficacy in vivo.

A role of the epidermal growth factor receptor (EGFR) family has been suggested in colon cancer etiology, progression, and/or severity. Our recently identified pan-erbB inhibitor EGFR-related protein (ERRP) targets EGFRs by attenuating their activation and subsequent signaling leading to cellular growth inhibition. In the present study, we evaluated the therapeutic effectiveness of ERRP on early and intermediate stages of colon cancer by examining regression of chemically induced aberrant crypt foci (ACF) in the colon of CF1 mice and intestinal adenomas in APCMin+/− (Min) mice. After formation of ACF or adenomas, the mice were injected (i.p.) with ERRP (50 μg/mouse) for 10 consecutive days. This treatment significantly reduced the number of ACF from 25.0 ± 3.0 (controls) to 14.9 ± 1.6 (ERRP-treated; P = 0.011) and also reduced their size (P < 0.01). In Min mice, ERRP caused the regression of adenomas throughout the small intestine (P < 0.05) and reduced their size (P < 0.001). This could partly be attributed to inhibition of proliferation and stimulation of apoptosis in the intestinal mucosa and was associated with decreased activation of several EGFR family members, suppression of downstream effector nuclear factor κB and down-regulation of cyclooxygenase-2. ERRP-induced attenuation of EGFR activation could be due to increased sequestration of the ligand(s) by ERRP, rendering them unavailable for binding to and activation of the receptor. In conclusion, our data show that ERRP is effective in regressing both early and intermediate intestinal lesions and could be an effective therapeutic agent for colon cancer. [Cancer Res 2007;67(11):5389–96]

Although in Fischer-344 rats, aging is associated with increased activation of EGF-receptor (EGFR) in mucosa of much of the gastrointestinal tract, including the colon, regulation of this process is poorly understood. We hypothesize that loss of suppressor of EGFR may partly be responsible for this process. To test this hypothesis, we examined the expression of EGFR related protein (ERRP), a recently identified negative regulator of EGFR, in the colonic mucosa during aging and following administration of the colonic carcinogen dimethylhydrazine (DMH) that resulted in the formation of aberrant crypt foci (ACF), which are considered to be precursor of adenoma and carcinoma. In Fischer-344 rats, aging is associated with increased activation of EGFR in the colonic mucosa, as evidenced by 30-35% increase in the levels of tyrosine phosphorylated EGFR in the proximal and distal colon of aged (20-22 months old) than in young (4-6 months old) rats. In contrast, the levels of ERRP in both regions of the colon of aged rats were decreased by 50-60%, compared to their younger counterparts. Administration of DMH, which induced a greater number of ACF in the colon of aged rats than in young animals, resulted in a corresponding reduction in ERRP in the colon. These results suggest that loss of ERRP expression is a common event during aging and early stages of chemically induced colon cancer. We also suggest that loss of ERRP could be a risk factor for developing colorectal cancer in the older population.

Dietary supplementation with milk sphingolipids inhibits colon tumorigenesis in CF1 mice treated with a colon carcinogen [1,2-dimethylhydrazine (DMH)] and in multiple intestinal neoplasia (Min) mice, which develop intestinal tumors spontaneously. Plant sphingolipids differ structurally from those of mammals [soy glucosylceramide (GlcCer) consists predominantly of a 4,8-sphingadiene backbone and alpha-hydroxy-palmitic acid], which might affect their bioactivity. Soy GlcCer was added to the AIN-76A diet (which contains0.005% sphingolipid) to investigate whether it would also suppress tumorigenesis in these mouse models. Soy GlcCer reduced colonic cell proliferation in the upper half of the crypts in mice treated with DMH by 50 and 56% (P0.05) at 0.025 and 0.1% of the diet (wt/wt), respectively, and reduced the number of aberrant colonic crypt foci (an early marker of colon carcinogenesis) by 38 and 52% (P0.05). Min mice fed diets containing 0.025 and 0.1% (wt/wt) soy GlcCer developed 22 and 37% fewer adenomas (P0.05), respectively. The effects of dietary sphingolipids on gene expression in the intestinal mucosal cells of Min mice were analyzed using Affymetrix GeneChip microarrays. Soy GlcCer affected the expression of 96 genes byor = 2-fold in a dose-dependent manner, increasing 32 and decreasing 64. Decreases in the mRNA expression of two transcription factors associated with cancer, hypoxia-induced factor 1 alpha (HIF1 alpha) and transcription factor 4 (TCF4), were confirmed by quantitative RT-PCR. In conclusion, soy GlcCer suppressed colon tumorigenesis in two mouse models; hence, plant sphingolipids warrant further investigation as inhibitors of colon cancer. Because soy contains relatively high amounts of GlcCer, sphingolipids may partially account for the anticancer benefits attributed to soy-based foods.

Socioeconomic status greatly affects cardiovascular risk factors and lifestyle. Aim of the study To analyse the relationship between socioeconomic status and both cardiovascular risk factors and behavioural variables. To analyse the relationship between socioeconomic status and both cardiovascular risk factors and behavioural variables. The present random sample of 838 men and 910 women of the 25 to 74 year old general population of Gerona according to the 1991 census, included cardiovascular risk factor measurements (total cholesterol, LDL cholesterol, HDL cholesterol, triglycerides, glycaemia, systolic blood pressure, diastolic blood pressure, body mass index, waist to hip ratio, and waist circumferences) and evaluation of dietary habits, alcohol consumption, smoking, and leisure-time physical activity with corresponding questionnaires. In this study, we used lifestyle factors (leisure-time physical activity, tobacco consumption, and alcohol drinking habits) in addition to dietary habits to determine whether changes in these factors correlate with the socioeconomic status, classified as degree of educational level, in a representative Spanish Mediterranean population. Multiple linear regression analysis adjusted for several confounders revealed a direct association of LDL-cholesterol (p = 0.03) and body mass index (p = 0.02) with low levels of educational status in men and women, respectively. A higher educational status was directly (p = 0.04) related to the smoking status in women. The two composite dietary scores, indicating overall dietary quality and cardiovascular protecting properties, were not associated with low socioeconomic status in our population. Dietary habits, alcohol drinking, and leisure-time physical activity seems not to be affected by educational status in either gender. This finding might partially explain the relationship between cardiovascular risk factors and socioeconomic status in our population. The importance of cultural values in the rural area of the Spanish province seems to be the stronger factor compared with education.

Intestinal cells are regularly exposed to sphingolipid metabolites, i.e., ceramide and sphingoid bases, after hydrolysis of complex sphingolipids from the diet. These metabolites are known regulators of cell growth, differentiation, and death. Non-pharmacological amounts in the diet have been shown to inhibit early stages of chemically induced colon cancer in mice. To distinguish between chemopreventive and chemotherapeutic effects of sphingomyelin supplements, mice were fed sphingomyelin before and after tumor initiation. Both applications drastically reduced tumor formation, without a significant difference among the groups, indicating that sphingolipids are as effective in the chemoprevention of tumors as in early intervention. The normalization of cell proliferation and rate of apoptosis, but not the induction of differentiation, seem to be key players in the suppression of tumor formation by dietary sphingomyelin. This may have implications for the development of a cancer prevention or treatment strategy with sphingolipids as an alternative to conventional drugs.

Aging and gastrointestinal malignancies, including that of the stomach are associated with increased activation of EGF-receptor (EGFR). Although the intracellular events that regulate this process are poorly understood, we hypothesize that loss of ERRP (EGFR-related protein; GenBank accession number AF187818), a recently identified negative regulator of EGFR, that possesses a substantial homology to the ligand binding extracellular domain of EGFR, may contribute to this event. In support of our hypothesis, we have observed that in Fischer-344 rats, whereas aging is associated with increased activation of EGFR in the gastric mucosa, expression of ERRP decreases in this tissue during this period. The latter is accompanied by a concomitant reduction in the amount of TGF-α bound to ERRP. In contrast, the amount of TGF-α bound to EGFR is found to be higher in the gastric mucosa of aged than in young rats. This is accompanied by a concomitant rise in EGFR levels. In the gastric mucosa, EGFR and ERRP are found to be colocalized. Gastric adenocarcinoma in humans, which has been shown to be associated with increased activation of EGFR, shows a substantial reduction in ERRP expression, when compared with benign tissues. We conclude that increased activation of EGFR in the gastric mucosa during aging and carcinogenesis may partly be due to the loss of ERRP.

Complex sphingolipids (sphingomyelin, cerebrosides, gangliosides) are natural components of our diet, amounting to an approximate intake of 0.3-0.4g per day. In the intestinal tract, they are digested to the bioactive metabolites ceramide and free sphingoid bases. These metabolites regulate proliferation, survival and cell death, alter gene expression levels and modulate functions such as angiogenesis, migration and invasion. They also impact local and systemic inflammation, affecting both epithelial and immune cells. Thus, they are involved in the regulation of functions that contribute to cancer cell promotion, progression and metastasis. Here we review evidence that dietary or orally administered sphingolipids are beneficial in the prevention of colon and other cancers in rodent models, and discuss the molecular mechanisms and cellular targets in the complex tumor microenvironment of the colon. We also investigate factors that contribute to a permissive tumor microenvironment such as inflammation, obesity and the intestinal microbiota as potential novel targets of dietary sphingolipids in the prevention of colon cancer.