Gut-liver axis calibrates intestinal stem cell fitness.

The gut and liver are recognized to mutually communicate through the biliary tract, portal vein, and systemic circulation. However, it remains unclear how this gut-liver axis regulates intestinal physiology. Through hepatectomy and transcriptomic and proteomic profiling, we identified pigment epithelium-derived factor (PEDF), a liver-derived soluble Wnt inhibitor, which restrains intestinal stem cell (ISC) hyperproliferation to maintain gut homeostasis by suppressing the Wnt/ß-catenin signaling pathway. Furthermore, we found that microbial danger signals resulting from intestinal inflammation can be sensed by the liver, leading to the repression of PEDF production through peroxisome proliferator-activated receptor-α (PPARα). This repression liberates ISC proliferation to accelerate tissue repair in the gut. Additionally, treating mice with fenofibrate, a clinical PPARα agonist used for hypolipidemia, enhances colitis susceptibility due to PEDF activity. Therefore, we have identified a distinct role for PEDF in calibrating ISC expansion for intestinal homeostasis through reciprocal interactions between the gut and liver.

Obesity facilitated colon cancer progression is mediated by increased diacylglycerol o-acyltransferases 1 and 2 (DGAT1/2) levels.

BACKGROUND & AIMS: The obesity epidemic is associated with increased colon cancer progression. As lipid droplets (LDs) fuel tumor growth, we aim to determine the significance of diacyltransferases, DGAT1/2, responsible for LDs biogenesis, in obesity-mediated colonic tumorigenesis. METHODS: Human colon cancer samples, colon cancer cells, colonospheres, and ApcMin/+ colon cancer mouse model on a high-fat diet were employed. For DGAT1/2 inhibition, enzymatic inhibitors and siRNA were used. Expression, pathways, cell cycle, and growth were assessed. Bioinformatic analyses of CUT&RUN and RNAseq data were performed. RESULTS: DGAT1/2 levels in human colon cancer tissue are significantly elevated with disease severity and obesity (vs normal). Their levels are increased in human colon cancer cells (vs non-transformed) and further enhanced by fatty acids prevalent in obesity; augmented DGAT2 expression is MYC-dependent. Inhibition of DGAT1/2 improves FOXO3 activity by attenuating PI3K, resulting in reduced MYC-dependent DGAT2 expression and LDs accumulation, suggesting feedback. This inhibition attenuated growth in colon cancer cells and colonospheres via FOXO3/p27kip1 cell cycle arrest and reduced colonic tumors in ApcMin/+ mice on a high-fat diet. Transcriptomic analysis revealed that DGAT1/2 inhibition targeted metabolic and tumorigenic pathways in human colon cancer and colon cancer crypts, stratifying human colon cancer samples from normal. Further analysis revealed that this inhibition is predictive of advanced disease-free state and survival in colon cancer patients. CONCLUSION: This is a novel mechanism of DGAT1/2-dependent metabolic and tumorigenic remodeling in obesity-facilitated colon cancer, providing a platform for the future development of effective treatments for colon cancer patients.

PEDF Deletion Induces Senescence and Defects in Phagocytosis in the RPE.

The retinal pigment epithelium (RPE) expresses the Serpinf1 gene to produce pigment epithelium-derived factor (PEDF), a retinoprotective protein that is downregulated with cell senescence, aging and retinal degenerations. We determined the expression of senescence-associated genes in the RPE of 3-month-old mice that lack the Serpinf1 gene and found that Serpinf1 deletion induced H2ax for histone H2AX protein, Cdkn1a for p21 protein, and Glb1 gene for ß-galactosidase. Senescence-associated ß-galactosidase activity increased in the Serpinf1 null RPE when compared with wild-type RPE. We evaluated the subcellular morphology of the RPE and found that ablation of Serpinf1 increased the volume of the nuclei and the nucleoli number of RPE cells, implying chromatin reorganization. Given that the RPE phagocytic function declines with aging, we assessed the expression of the Pnpla2 gene, which is required for the degradation of photoreceptor outer segments by the RPE. We found that both the Pnpla2 gene and its protein PEDF-R declined with the Serpinf1 gene ablation. Moreover, we determined the levels of phagocytosed rhodopsin and lipids in the RPE of the Serpinf1 null mice. The RPE of the Serpinf1 null mice accumulated rhodopsin and lipids compared to littermate controls, implying an association of PEDF deficiency with RPE phagocytosis dysfunction. Our findings establish PEDF loss as a cause of senescence-like changes in the RPE, highlighting PEDF as both a retinoprotective and a regulatory protein of aging-like changes associated with defective degradation of the photoreceptor outer segment in the RPE.

Loss of ephrin B2 receptor (EPHB2) sets lipid rheostat by regulating proteins DGAT1 and ATGL inducing lipid droplet storage in prostate cancer cells.

Lipid droplet (LD) accumulation in cancer results from aberrant metabolic reprograming due to increased lipid uptake, diminished lipolysis and/or de novo lipid synthesis. Initially implicated in storage and lipid trafficking in adipocytes, LDs are more recently recognized to fuel key functions associated with carcinogenesis and progression of several cancers, including prostate cancer (PCa). However, the mechanisms controlling LD accumulation in cancer are largely unknown. EPHB2, a tyrosine kinase (TKR) ephrin receptor has been proposed to have tumor suppressor functions in PCa, although the mechanisms responsible for these effects are unclear. Given that dysregulation in TRK signaling can result in glutaminolysis we postulated that EPHB2 might have potential effects on lipid metabolism. Knockdown strategies for EPHB2 were performed in prostate cancer cells to analyze the impact on the net lipid balance, proliferation, triacylglycerol-regulating proteins, effect on LD biogenesis, and intracellular localization of LDs. We found that EPHB2 protein expression in a panel of human-derived prostate cancer cell lines was inversely associated with in vivo cell aggressiveness. EPHB2 silencing increased the proliferation of prostate cancer cells and concurrently induced de novo LD accumulation in both cytoplasmic and nuclear compartments as well as a "shift" on LD size distribution in newly formed lipid-rich organelles. Lipid challenge using oleic acid exacerbated the effects on the LD phenotype. Loss of EPHB2 directly regulated key proteins involved in maintaining lipid homeostasis including, increasing lipogenic DGAT1, DGAT2 and PLIN2 and decreasing lipolytic ATGL and PEDF. A DGAT1-specific inhibitor abrogated LD accumulation and proliferative effects induced by EPHB2 loss. In conclusion, we highlight a new anti-tumor function of EPHB2 in lipid metabolism through regulation of DGAT1 and ATGL in prostate cancer. Blockade of DGAT1 in EPHB2-deficient tumors appears to be effective in restoring the lipid balance and reducing tumor growth.

Heterogeneity of human prostate carcinoma-associated fibroblasts implicates a role for subpopulations in myeloid cell recruitment.

BACKGROUND: Carcinoma-associated fibroblasts (CAF) are a heterogeneous group of cells within the tumor microenvironment (TME) that can promote tumorigenesis in the prostate. By understanding the mechanism(s) by which CAF contributes to tumor growth, new therapeutic targets for the management of this disease may be identified. These studies determined whether unique sub-populations of human prostate CAF can be identified and functionally characterized. METHODS: Single-cell RNA-seq of primary human prostate CAF followed by unsupervised clustering was utilized to generate cell clusters based on differentially expressed (DE) gene profiles. Potential communication between CAF and immune cells was analyzed using in vivo tissue recombination by combining CAF or normal prostate fibroblasts (NPF) with non-tumorigenic, initiated prostate epithelial BPH-1 cells. Resultant grafts were assessed for inflammatory cell recruitment. RESULTS: Clustering of 3321 CAF allows for visualization of six subpopulations, demonstrating heterogeneity within CAF. Sub-renal capsule recombination assays show that the presence of CAF significantly increases myeloid cell recruitment to resultant tumors. This is supported by significantly increased expression of chemotactic chemokines CCL2 and CXCL12 in large clusters compared to other subpopulations. Bayesian analysis topologies also support differential communication signals between chemokine-related genes of individual clusters. Migration of THP-1 monocyte cells in vitro is stimulated in the presence of CAF conditioned medium (CM) compared with NPF CM. Further in vitro analyses suggest that CAF-derived chemokine CCL2 may be responsible for CAF-stimulated migration of THP-1 cells, since neutralization of this chemokine abrogates migration capacity. CONCLUSIONS: CAF clustering based on DE gene expression supports the concept that clusters have unique functions within the TME, including a role in immune/inflammatory cell recruitment. These data suggest that CCL2 produced by CAF may be involved in the recruitment of inflammatory cells, but may also directly regulate the growth of the tumor. Further studies aimed at characterizing the subpopulation(s) of CAF which promote immune cell recruitment to the TME and/or stimulate prostate cancer growth and progression will be pursued.

PEDF regulates plasticity of a novel lipid-MTOC axis in prostate cancer-associated fibroblasts.

Prostate tumors make metabolic adaptations to ensure adequate energy and amplify cell cycle regulators, such as centrosomes, to sustain their proliferative capacity. It is not known whether cancer-associated fibroblasts (CAFs) undergo metabolic re-programming. We postulated that CAFs augment lipid storage and amplify centrosomal or non-centrosomal microtubule-organizing centers (MTOCs) through a pigment epithelium-derived factor (PEDF)-dependent lipid-MTOC signaling axis. Primary human normal prostate fibroblasts (NFs) and CAFs were evaluated for lipid content, triacylglycerol-regulating proteins, MTOC number and distribution. CAFs were found to store more neutral lipids than NFs. Adipose triglyceride lipase (ATGL) and PEDF were strongly expressed in NFs, whereas CAFs had minimal to undetectable levels of PEDF or ATGL protein. At baseline, CAFs demonstrated MTOC amplification when compared to 1-2 perinuclear MTOCs consistently observed in NFs. Treatment with PEDF or blockade of lipogenesis suppressed lipid content and MTOC number. In summary, our data support that CAFs have acquired a tumor-like phenotype by re-programming lipid metabolism and amplifying MTOCs. Normalization of MTOCs by restoring PEDF or by blocking lipogenesis highlights a previously unrecognized plasticity in centrosomes, which is regulated through a new lipid-MTOC axis.This article has an associated First Person interview with the first author of the paper.

PEDF deficiency increases the susceptibility of rd10 mice to retinal degeneration.

The SERPINF1 gene encodes pigment epithelium-derived factor (PEDF), a member of the serpin superfamily with neurotrophic and antiangiogenic properties in the retina. We hypothesized that absence of PEDF would lead to increased stress-associated retinal degeneration in Serpinf1 null mice. Accordingly, using a Serpinf1 null mouse model, we investigated the impact of PEDF absence on retinal morphology, and susceptibility to induced and inherited retinal degeneration. We studied the pattern of Serpinf1 expression in the mouse retina layers. PEDF protein was detected by western blotting. Transmission electron microscopy was performed on mouse retina. Serpinf1 null mice and wild type littermates were injected with NaIO3 (30 mg/kg body weight) intraperitonially. At post-injection day 1, 3, 4, 6 and 8 mice were euthanized, and eyes were enucleated. Serpinf1 null and rd10 double mutant mice were generated and their eyes enucleated at different time points from post-natal day 15 to post-natal day 28. Enucleated eyes were processed for hematoxylin and eosin staining and histopathological evaluations. We found that Serpinf1 was expressed in the retinal pigment epithelium, in the inner nuclear layer and in the ganglion cell layer, but undetectable in the outer nuclear layer of wild type mice. Plasma PEDF protein levels were undetectable in Serpinf1 null animals. RPE atrophy and retinal thinning were observed in NaIO3-treated wild type mice that progressed with time post-injection. NaIO3-treated Serpinf1 null mice showed comparatively better retinal morphology than wild type mice at day 4 post-injection. However, the absence of PEDF in Serpinf1 null x rd10 mice increased the susceptibility to retinal degeneration relative to that of rd10 mice. We concluded that histopathological evaluation of retinas lacking PEDF showed that removal of the Serpinf1 gene may activate PEDF-independent compensatory mechanisms to protect the retina against oxidative stress, while it increases the susceptibility to degenerate the retina in inherited retinal degeneration models.

Lipid droplet velocity is a microenvironmental sensor of aggressive tumors regulated by V-ATPase and PEDF.

Lipid droplets (LDs) utilize microtubules (MTs) to participate in intracellular trafficking of cargo proteins. Cancer cells accumulate LDs and acidify their tumor microenvironment (TME) by increasing the proton pump V-ATPase. However, it is not known whether these two metabolic changes are mechanistically related or influence LD movement. We postulated that LD density and velocity are progressively increased with tumor aggressiveness and are dependent on V-ATPase and the lipolysis regulator pigment epithelium-derived factor (PEDF). LD density was assessed in human prostate cancer (PCa) specimens across Gleason scores (GS) 6-8. LD distribution and velocity were analyzed in low and highly aggressive tumors using live-cell imaging and in cells exposed to low pH and/or treated with V-ATPase inhibitors. The MT network was disrupted and analyzed by α-tubulin staining. LD density positively correlated with advancing GS in human tumors. Acidification promoted peripheral localization and clustering of LDs. Highly aggressive prostate, breast, and pancreatic cell lines had significantly higher maximum LD velocity (LDVmax) than less aggressive and benign cells. LDVmax was MT-dependent and suppressed by blocking V-ATPase directly or indirectly with PEDF. Upon lowering pH, LDs moved to the cell periphery and carried metalloproteinases. These results suggest that acidification of the TME can alter intracellular LD movement and augment velocity in cancer. Restoration of PEDF or blockade of V-ATPase can normalize LD distribution and decrease velocity. This study identifies V-ATPase and PEDF as new modulators of LD trafficking in the cancer microenvironment.

Hyperglycemia and T Cell infiltration are associated with stromal and epithelial prostatic hyperplasia in the nonobese diabetic mouse.

BACKGROUND: Prostatic inflammation and various proinflammatory systemic comorbidities, such as diabetes and obesity are associated with human benign prostatic hyperplasia (BPH). There is a paucity of in vivo models reflecting specific aspects of BPH pathogenesis. Our aim was to investigate the nonobese diabetic (NOD) mouse as a potential model for subsequent intervention studies. MATERIALS AND METHODS: We used the NOD mouse, a model of autoimmune inflammation leading to type 1 diabetes to examine the effects of systemic inflammation and diabetes on the prostate. We assessed changes in prostatic histology, infiltrating leukocytes, and gene expression associated with aging and diabetic status. RESULTS: Both stromal expansion and epithelial hyperplasia were observed in the prostates. Regardless of diabetic status, the degree of prostatic hyperplasia varied. Local inflammation was associated with a more severe prostatic phenotype in both diabetic and nondiabetic mice. Testicular atrophy was noted in diabetic mice, but prostate glands showed persistent focal cell proliferation. In addition, a prostatic intraepithelial neoplasia (PIN)-like phenotype was seen in several diabetic animals with an associated increase in c-Myc and MMP-2 expression. To examine changes in gene and cytokine expression we performed microarray and cytokine array analysis comparing the prostates of diabetic and nondiabetic animals. Microarray analysis revealed several differentially expressed genes including CCL3, CCL12, and TNFS10. Cytokine array analysis revealed increased expression of cytokines and proteases such as LDLR, IL28 A/B, and MMP-2 in diabetic mice. CONCLUSION: Overall, NOD mice provide a model to examine the effects of hyperglycemia and chronic inflammation on the prostate, demonstrating relevance to some of the mechanisms present underlying BPH and potentially the initiation of prostate cancer.

Tyrosine kinase inhibitor therapy prescribed for non-urologic diseases can modify PSA titers in urology patients.

BACKGROUND: The tyrosine kinase inhibitors (TKI), imatinib and nilotinib, are used to treat chronic myelogenous leukemia (CML). In three CML patients being monitored for urologic diseases, we observed that switching of TKI therapy affected prostate-specific antigen (PSA) titers. Urologists and other medical professionals need to be aware of the potential side-effects of drugs that patients may be receiving for other indications to modify this important prostate diseases indicator. TKIs may affect PSA titers independent of prostate growth or volume. MATERIALS AND METHODS: We followed PSA levels in urology patients who were also undergoing TKI treatment for CML. We determined the effects of nilotinib and imatinib on proliferation, AR and PSA expression in the LNCaP and 22Rv1 prostate cancer (PCa) cell lines using real-time PCR and Western blotting. RESULTS: Clinically, nilotinib and dasatinib reversibly reduced PSA titers compared to imatinib. At high doses nilotinib and imatinib both demonstrated antiproliferative effects in the PCa cells. At low doses expression of AR and PSA was decreased by both drugs, at mRNA and protein levels. Nilotinib exerted greater effects at lower doses than imatinib. CONCLUSIONS: Nilotinib down-regulates serum PSA in patients being treated for non-urological indications, potentially masking a clinical useful marker, we cannot exclude a similar but smaller effect of imatinib. Nilotinib and imatinib both decreased AR and PSA expression in PCa cell lines with the nilotinib effect evident at lower doses. Urologists must appreciate the effects of drugs provided for other diseases on PSA titers and be aware that sudden changes may not reflect underlying prostatic disease.

Reduced mitochondrial activity in colonocytes facilitates AMPKα2-dependent inflammation.

Intestinal inflammation is associated with low levels of mucosal ATP, highlighting the importance of mitochondrial function associated with ATP production in the pathophysiology of the disease. In the inflamed colon of humans and mice, we found decreased levels of mitochondrial complex cytochrome c oxidase I/IV and lower ATP levels. Thus, we generated colonic ρ0 cells with reduced mitochondrial function linked to ATP production by selective depletion of mitochondrial DNA. In these cells, RNA sequencing revealed a substantial number of differentially expressed transcripts, among which 240 belonged to inflammatory pathways activated in human inflamed colon and TNF-α-treated cells (false discovery rate < 0.05). TNF-α treatment of colonic ρ0 cells augmented IL-8 expression by 9-fold (P < 0.01) via NF-κB compared to TNF-α-treated control. Moreover, reduced mitochondrial function facilitated TNF-α-mediated NF-κB luciferase promoter activity as a result of lowered inhibitory IκBα (nuclear factor of κ light polypeptide gene enhancer in B-cell inhibitor, α), leading to elevated NF-κB. In cells with reduced mitochondrial function, TNF-α facilitated AMPKα2 activation by 8-fold (P < 0.01), which was involved in NF-κB-dependent IL-8 expression. Last, in human and mouse colon, anti-TNF-α treatment restored reduced mitochondria-dependent inflammation. We propose that selective targeting of this novel mechanism provides new treatment opportunities for intestinal inflammation.-Heller, S., Penrose, H. M., Cable, C., Biswas, D., Nakhoul, H., Baddoo, M., Flemington, E., Crawford, S. E., Savkovic, S. D. Reduced mitochondrial activity in colonocytes facilitates AMPKα2-dependent inflammation.

High-fat diet induced leptin and Wnt expression: RNA-sequencing and pathway analysis of mouse colonic tissue and tumors.

Obesity, an immense epidemic affecting approximately half a billion adults, has doubled in prevalence in the last several decades. Epidemiological data support that obesity, due to intake of a high-fat, western diet, increases the risk of colon cancer; however, the mechanisms underlying this risk remain unclear. Here, utilizing next generation RNA sequencing, we aimed to determine the high-fat diet (HFD) mediated expression profile in mouse colon and the azoxymethane/dextran sulfate sodium model of colon cancer. Mice on HFD had significantly higher colonic inflammation, tumor burden, and a number of differentially expressed transcripts compared to mice on regular diet (RD). We identified 721 transcripts differentially expressed in mouse HFD colon that were in a shared pattern with colonic tumors (RD and HFD). Importantly, in mouse colon, HFD stimulated an expression signature strikingly similar to human colon cancer, especially those with inflammatory microsatellite instability. Furthermore, pathway analysis of these transcripts demonstrated their association with active inflammation and colon cancer signaling, with leptin and Wnt as the top two transcripts elevated in mouse HFD colon shared with tumors. Moreover, in mouse colon, HFD-stimulated tumorigenic Wnt pathway activation was further validated by upregulation of ß-catenin transcriptional targets. Finally, in human colon cancer, upregulation of leptin pathway members was shown with a large network of dysregulated transcripts being linked with worse overall survival.

A genetic variant near GATA3 implicated in inherited susceptibility and etiology of benign prostatic hyperplasia (BPH) and lower urinary tract symptoms (LUTS).

BACKGROUND: Benign prostatic hyperplasia (BPH) and associated lower urinary tract symptoms (LUTS) are common conditions. Little is known about their etiologies except that studies have suggested a substantial heritable component. Our objective is to provide a comprehensive, genome-wide evaluation of inherited risks and possible mechanisms of etiology in BPH. METHODS: We performed a three-stage, genome-wide association study (GWAS) of men from three independent populations, the REduction by DUtasteride of prostate Cancer Events (REDUCE) trial, the CLUE II cohort, and a Finnish hospital-based population. DNA samples were genotyped using the Illumina HumanOmniExpress BeadChip in REDUCE and CLUE II, and using the Sequenom iPLEX system for the confirmation stage in the Finnish population. A logistic regression model was used to evaluate the association between each SNP and BPH/LUTS. RESULTS: Fourteen SNPs reached P < 5.0 × 10-4 in the meta-analysis of the two GWASs (CLUE II and REDUCE). A total of 773 SNPs were chosen for the confirmation step in the Finish cohort. Only one SNP (rs17144046) located ∼489 kb downstream of GATA3 remained significant after correction for multiple testing (P < 6.5 × 10-5 ). This SNP marginally reached the GWAS significance level after performing a meta-analysis of the three stages (P-meta = 8.89 × 10-7 ). Expression quantitative trait loci (eQTL) analyses showed that the risk allele (G) of rs17144046 was significantly associated with increased expression of GATA3 (P = 0.017). Reported studies indicated a close correlation between GATA3 and BPH pathogenesis and progression. CONCLUSIONS: Rs17144046 located near GATA3 was significantly associated with BPH/LUTS in three independent populations, but did not reach a stringent GWAS significance level. Genetic variants of GATA3 may play a role in the inherited susceptibility and etiology of BPH/LUTS. Further research in this area is needed.

Altered TGF-α/ß signaling drives cooperation between breast cancer cell populations.

The role of tumor heterogeneity in regulating disease progression is poorly understood. We hypothesized that interactions between subpopulations of cancer cells can affect the progression of tumors selecting for a more aggressive phenotype. We developed an in vivo assay based on the immortalized nontumorigenic breast cell line MCF10A and its Ras-transformed derivatives AT1 (mildly tumorigenic) and CA1d (highly tumorigenic). CA1d cells outcompeted MCF10A, forming invasive tumors. AT1 grafts were approximately 1% the size of CA1d tumors when initiated using identical cell numbers. In contrast, CA1d/AT1 mixed tumors were larger than tumors composed of AT1 alone (100-fold) or CA1d (3-fold), suggesting cooperation in tumor growth. One of the mechanisms whereby CA1d and AT1 were found to cooperate was by modulation of TGF-α and TGF-ß signaling. Both of these molecules were sufficient to induce changes in AT1 proliferative potential in vitro. Reisolation of AT1 tumor-derived (AT1-TD) cells from these mixed tumors revealed that AT1-TD cells grew in vivo, forming tumors as large as tumorigenic CA1d cells. Cooperation between subpopulations of cancer epithelium is an understudied mechanism of tumor growth and invasion that may have implications on tumor resistance to current therapies.-Franco, O. E., Tyson, D. R., Konvinse, K. C., Udyavar, A. R., Estrada, L., Quaranta, V., Crawford, S. E., Hayward, S. W. Altered TGF-α/ß signaling drives cooperation between breast cancer cell populations.

Intestinal inflammation requires FOXO3 and prostaglandin E2-dependent lipogenesis and elevated lipid droplets.

Intestinal inflammation has been recently characterized by the dysregulation of lipids as metabolic and energy sources, revealing a novel feature of its pathophysiology. Because intracellular lipids, stored in dynamic lipid droplets (LDs), provide energy for cellular needs, we investigated whether they play a role in intestinal inflammation. In the inflamed intestine of mice, elevated LDs were found in colonic and infiltrating immune cells as shown by staining for the LD coat protein PLIN2 and for lipids with BODIPY. In colonic cells, TNF stimulated LD increases by receptor signaling rely on phosphatidylinositol 3-kinase activation. Downstream, TNF triggered a negative regulatory loop between LDs and the transcription factor FOXO3. This was shown in the colon of Foxo3-deficient mice, where elevation in PLIN2 and lipids were further facilitated by inflammation and were more prominent relative to wild-type, whereas, in colonic cells, inhibition of lipogenesis blocked the TNF-mediated loss of FOXO3. Furthermore, blockade of PGE2 synthesis abrogated TNF-stimulated increases in LDs and FOXO3 inactivation. We found in colonic tissue of Foxo3-deficient mice higher levels of cyclooxygenase-2, a mediator of prostaglandin E2 (PGE2) synthesis, supporting involvement of PGE2 in the LD-FOXO3 regulatory loop. Ultimately, TNF-stimulated lipogenesis leading to elevated LDs facilitated NF-κB-mediated increases in IL-8 protein, which is associated with the surface of LDs found in the lumina of the endoplasmic reticulum and Golgi apparatus. This novel immunometabolic mechanism of colonic inflammation involving elevated LDs could provide opportunities for new treatment options.

Epidermal growth factor receptor mediated proliferation depends on increased lipid droplet density regulated via a negative regulatory loop with FOXO3/Sirtuin6.

The proliferation of colon cancer cells is mediated in part by epidermal growth factor receptor (EGFR) signaling and requires sustained levels of cellular energy to meet its high metabolic needs. Intracellular lipid droplets (LDs) are a source of energy used for various cellular functions and they are elevated in density in human cancer, yet their regulation and function are not well understood. Here, in human colon cancer cells, EGF stimulates increases in LD density, which depends on EGFR expression and activation as well as the individual cellular capacity for lipid synthesis. Increases in LDs are blockaded by inhibition of PI3K/mTOR and PGE2 synthesis, supporting their dependency on select upstream pathways. In colon cancer cells, silencing of the FOXO3 transcription factor leads to down regulation of SIRT6, a negative regulator of lipid synthesis, and consequent increases in the LD coat protein PLIN2, revealing that increases in LDs depend on loss of FOXO3/SIRT6. Moreover, EGF stimulates loss of FOXO3/SIRT6, which is blockaded by the inhibition of upstream pathways as well as lipid synthesis, revealing existence of a negative regulatory loop between LDs and FOXO3/SIRT6. Elevated LDs are utilized by EGF treatment and their depletion through the inhibition of lipid synthesis or silencing of PLIN2 significantly attenuates proliferation. This novel mechanism of proliferative EGFR signaling leading to elevated LD density in colon cancer cells could potentially be therapeutically targeted for the treatment of tumor progression.

MRS measured fatty acid composition of periprostatic adipose tissue correlates with pathological measures of prostate cancer aggressiveness.

PURPOSE: To investigate the association between magnetic resonance (MR) spectroscopically measured fatty acid composition of periprostatic adipose tissue and pathological markers of prostate cancer aggressiveness. MATERIALS AND METHODS: Periprostatic adipose (PPA) and subcutaneous adipose (SQA) tissue from prostate cancer patients undergoing radical prostatectomy were examined ex vivo by proton MR spectroscopy at 14.1T (n = 31). Fractions of monounsaturated, polyunsaturated, total unsaturated, and saturated fatty acids, as well as T2 relaxation times were measured from the spectra. Univariate and multivariate analyses based on receiver operating characteristic (ROC) and support vector machines (SVM) were used to evaluate the association between differential measures of fatty acid levels in the PPA and SQA tissues and Gleason score and extracapsular extension (ECE), which are pathological measures of prostate cancer aggressiveness. RESULTS: Both pathological markers for aggressive prostate cancer have separable patterns in the MRS features space. The association between ECE and PPA tissue fatty acid composition is linear (area under receiver operating characteristic curve (AROC) and 95% confidence intervals [CIs]: 1.00, [1.00, 1.00]), along the Δ(fM /fS ) measure, and is marked by elevated monounsaturated and reduced saturated fatty acids in the PPA tissue relative to SQA. In contrast, the association between Gleason score and PPA tissue fatty acid composition is nonlinear (classifier AROC and 95% CIs: 0.86, [0.71, 1.00]). CONCLUSION: Fatty acid composition is altered in the PPA tissue of patients with aggressive prostate cancer. Ex vivo MR spectroscopy may be a useful tool in studying the altered fatty acid metabolism in prostate cancer.

Depletion of polymorphonuclear leukocytes has no effect on preterm delivery in a mouse model of Escherichia coli-induced labor.

OBJECTIVE: The objective of the study was to investigate the role of polymorphonuclear leukocytes (PMNs) in a mouse model of Escherichia coli-induced labor. STUDY DESIGN: Intraperitoneal injection of rabbit antimouse PMN antiserum or control was performed in CD-1 mice 29 hours and 5 hours prior to laparotomy and intrauterine injection of either killed E coli or phosphate-buffered saline on day 14.5 of pregnancy. Preterm delivery was defined as delivery of at least 1 pup within 48 hours. Circulating leukocyte counts were determined manually or by flow cytometry at the time of surgery and 8, 24, and 48 hours afterward. Maternal and fetal tissues were analyzed in a separate group of animals 8 hours after surgery. RESULTS: Pretreatment with anti-PMN antiserum significantly decreased the numbers of circulating leukocytes and the proportion of neutrophils among all leukocytes by 70-80% at surgery and at least 8 hours thereafter. Neutrophil depletion significantly reduced 2 markers of neutrophil activation in the uterus and placenta (neutrophil elastase and myeloperoxidase activity) and neutrophil infiltration into gestational tissues in bacterially treated animals to baseline (control) levels but did not affect preterm birth rates. The large E coli-induced increases in uterine inflammatory markers (interleukin-1ß, tumor necrosis factor, chemokine ligand-5, cyclooxygenase-2) were not affected or were only minimally affected by neutrophil depletion. CONCLUSION: Although PMN antiserum reduces both neutrophil number and activity, it does not diminish sensitivity to bacterially induced delivery or meaningfully alter the expression of inflammatory markers in the mouse model. Preterm birth and inflammation in this model are not likely to depend on neutrophil function.

FOXO3 growth inhibition of colonic cells is dependent on intraepithelial lipid droplet density.

Forkhead transcription factor FOXO3 plays a critical role in suppressing tumor growth, in part, by increasing the cell cycle inhibitor p27kip1, and Foxo3 deficiency in mice results in marked colonic epithelial proliferation. Here, we show in Foxo3-deficient colonic epithelial cells a striking increase in intracytoplasmic lipid droplets (LDs), a dynamic organelle recently observed in human tumor tissue. Although the regulation and function of LDs in non-adipocytes is unclear, we hypothesize that the anti-proliferative effect of FOXO3 was dependent on lowering LD density, thus decreasing fuel energy in both normal and colon cancer cells. In mouse colonic tumors, we found an increased expression of LD coat protein PLIN2 compared with normal colonic epithelial cells. Stimulation of LD density in human colon cancer cells led to a PI3K-dependent loss of FOXO3 and a decrease in the negative regulator of lipid metabolism in Sirtuin6 (SIRT6). Foxo3 deficiency also led to a decrease in SIRT6, revealing the existence of LD and FOXO3 feedback regulation in colonic cells. In parallel, LD-dependent loss of FOXO3 led to its dissociation from the promoter and decreased expression of the cell cycle inhibitor p27kip1. Stimulation of LD density promoted proliferation in colon cancer cells, whereas silencing PLIN2 or overexpression of FOXO3 inhibited proliferation. Taken together, FOXO3 and LDs might serve as new targets for therapeutic intervention of colon cancer.

Periprostatic adipose tissue from obese prostate cancer patients promotes tumor and endothelial cell proliferation: a functional and MR imaging pilot study.

BACKGROUND: Obesity, particularly visceral adiposity, confers a worse prognosis for prostate cancer (PCa) patients, and increasing periprostatic adipose (PPA) tissue thickness or density is positively associated with more aggressive disease. However, the cellular mechanism of this activity remains unclear. Therefore, in this pilot study, we assessed the functional activity of PPA tissue secretions and established a biochemical profile of PPA as compared to subcutaneous adipose (SQA) tissues from lean, overweight and obese PCa patients. METHODS: Adipose tissues were collected from PCa patients undergoing surgical prostate removal. Tissues were analyzed by histologic and magnetic resonance (MR) techniques. Explant tissue culture secretions were used in proliferation assays on PCa and endothelial cells. RESULTS: PPA secretions obtained from obese patients were significantly more pro-proliferative in both PCa and endothelial cells as compared to PPA obtained from lean or overweight men and SQA tissues. Consistent with this, PPA microvessel density was increased, and the T2 relaxation time was decreased, compared to SQA tissues, and we observed a modest, inverse correlation between the T2 and tumor stage. Moreover, the ratio of unsaturated to saturated fatty acids, obtained using MR spectroscopy, showed a modest, inverse correlation with Gleason score. CONCLUSIONS: These pilot data show that PPA stimulates PCa cell proliferation and angiogenesis and that obesity intensifies this activity, thus generating a mechanistic hypothesis to explain the worse prognosis observed in obese PCa patients. Our pilot study also shows that MR technology may be useful in further elucidating the relationship between obesity and PCa progression.