Overexpression of Fatty Acid Synthase Upregulates Glutamine-Fructose-6-Phosphate Transaminase 1 and O-Linked N-Acetylglucosamine Transferase to Increase O-GlcNAc Protein Glycosylation and Promote Colorectal Cancer Growth.

Fatty acid synthesis has been extensively investigated as a therapeutic target in cancers, including colorectal cancer (CRC). Fatty acid synthase (FASN), a key enzyme of de novo lipid synthesis, is significantly upregulated in CRC, and therapeutic approaches of targeting this enzyme are currently being tested in multiple clinical trials. However, the mechanisms behind the pro-oncogenic action of FASN are still not completely understood. Here, for the first time, we show that overexpression of FASN increases the expression of glutamine-fructose-6-phosphate transaminase 1 (GFPT1) and O-linked N-acetylglucosamine transferase (OGT), enzymes involved in hexosamine metabolism, and the level of O-GlcNAcylation in vitro and in vivo. Consistently, expression of FASN significantly correlates with expression of GFPT1 and OGT in human CRC tissues. shRNA-mediated downregulation of GFPT1 and OGT inhibits cellular proliferation and the level of protein O-GlcNAcylation in vitro, and knockdown of GFPT1 leads to a significant decrease in tumor growth and metastasis in vivo. Pharmacological inhibition of GFPT1 and OGT leads to significant inhibition of cellular proliferation and colony formation in CRC cells. In summary, our results show that overexpression of FASN increases the expression of GFPT1 and OGT as well as the level of protein O-GlcNAcylation to promote progression of CRC; targeting the hexosamine biosynthesis pathway could be a therapeutic approach for this disease.

Membrane associated collagen XIII promotes cancer metastasis and enhances anoikis resistance.

BACKGROUND: Increased collagen expression and deposition are associated with cancer progression and poor prognosis in breast cancer patients. However, function and regulation of membrane-associated collagen in breast cancer have not been determined. Collagen XIII is a type II transmembrane protein within the collagen superfamily. Experiments in tissue culture and knockout mouse models show that collagen XIII is involved in cell adhesion and differentiation of certain cell types. In the present study, we determined roles of collagen XIII in breast cancer progression and metastasis. METHODS: We analyzed the association of collagen XIII expression with breast cancer development and metastasis using published gene expression profiles generated from human breast cancer tissues. Utilizing gain- and loss- of function approaches and 3D culture assays, we investigated roles of collagen XIII in regulating invasive tumor growth. Using the tumorsphere/mammosphere formation assay and the detachment cell culture assay, we determined whether collagen XIII enhances cancer cell stemness and induces anoikis resistance. We also inhibited collagen XIII signaling with ß1 integrin function-blocking antibody. Finally, using the lung colonization assay and the orthotopic mammary tumor model, we investigated roles of collagen XIII in regulating breast cancer colonization and metastasis. Cox proportional hazard (log-rank) test, two-sided Student's t-test (two groups) and one-way ANOVA (three or more groups) analyses were used in this study. RESULTS: Collagen XIII expression is significantly higher in human breast cancer tissue compared with normal mammary gland. Increased collagen XIII mRNA levels in breast cancer tissue correlated with short distant recurrence free survival. We showed that collagen XIII expression promoted invasive tumor growth in 3D culture, enhanced cancer cell stemness, and induced anoikis resistance. Collagen XIII expression induced ß1 integrin activation. Blocking ß1 integrin activation significantly reduced collagen XIII-induced invasion and mammosphere formation. Importantly, silencing collagen XIII in MDA-MB-231 cells reduced lung colonization and metastasis. CONCLUSIONS: Our results demonstrate a novel function of collagen XIII in promoting cancer metastasis, cell invasion, and anoikis resistance.

Development of murine bariatric surgery models: lessons learned.

Roux-en-Y gastric bypass (RYGB) improves comorbidities such as diabetes and hypertension and lowers the risk of obesity-related cancers. To better understand the physiologic and genetic influences of bariatric surgery, a reliable murine model is needed that can be extended to genetically engineered mice. Given the complexity of these procedures, few researchers have successfully implemented these techniques beyond larger rodent models. The purpose of our study was to develop a technically feasible and reproducible murine model for RYGB and sleeve gastrectomy (SG). Mice were converted to liquid diet perioperatively without fasting and housed in groups on raised wire platforms. SG involved significant reduction of stomach volume followed by multilayer repair of the gastrotomy. RYGB procedure consisted of side-to-side, functional end-to-side bowel anastomoses and exclusion of the stomach medial to the gastroesophageal junction. Sham surgeries consisted of enterotomies and gastrotomy followed by primary repair without resection or rerouting. Survival after incorporation of the aforementioned techniques was 100% in the SG group and 41% in the RYGB group at 1 mo after surgery. Only 26% of RYGB mortality was attributed to leak, obstruction, or stricture; the majority of postoperative mortality was due to stress, dumping, or malnutrition. Much of the survival challenge for this surgical model was related to perioperative husbandry, which is to be expected given their small stature and poor response to stress. Utilization of the perioperative and surgical techniques described will increase survival and feasibility of these technically challenging procedures, allowing for a better understanding of mechanisms to explain the beneficial effects of bariatric surgery.

Prolyl-4-hydroxylase α subunit 2 promotes breast cancer progression and metastasis by regulating collagen deposition.

BACKGROUND: Increased collagen deposition provides physical and biochemical signals to support tumor growth and invasion during breast cancer development. Therefore, inhibition of collagen synthesis and deposition has been considered a strategy to suppress breast cancer progression. Collagen prolyl-4-hydroxylase α subunit 2 (P4HA2), an enzyme hydroxylating proline residues in -X-Pro-Gly- sequences, is a potential therapeutic target for the disorders associated with increased collagen deposition. However, expression and function of P4HA2 in breast cancer progression are not well investigated. METHODS: Gene co-expression analysis was performed in the published microarray datasets to identify potential regulators of collagen I, III, and IV in human breast cancer tissue. Expression of P4HA2 was silenced by shRNAs, and its activity was inhibited by 1, 4-DPCA, a prolyl-4-hydroxylase inhibitor. Three-dimensional culture assay was used to analyze roles of P4HA2 in regulating malignant phenotypes of breast cancer cells. Reduced deposition of collagen I and IV was detected by Western blotting and immunofluorescence. Control and P4HA2-silenced breast cancer cells were injected into fat pad and tail vein of SCID mice to examine effect of P4HA2 on tumor growth and lung metastasis. RESULTS: Using gene co-expression analysis, we showed that P4HA2 was associated with expression of Col1A1, Col3A1, and Col4A1 during breast cancer development and progression. P4HA2 mRNA levels were significantly upregulated in breast cancer compared to normal mammary tissue. Increased mRNA levels of P4HA2 correlated with poor clinical outcome in breast cancer patients, which is independent of estrogen receptor status. Silencing P4HA2 expression or treatment with the P4HA inhibitor significantly inhibited cell proliferation and suppressed aggressive phenotypes of breast cancer cells in 3D culture, accompanied by reduced deposition of collagen I and IV. We also found that knockdown of P4HA2 inhibited mammary tumor growth and metastasis to lungs in xenograft models. CONCLUSION: These results suggest the critical role of P4HA2 in breast cancer progression and identify P4HA2 as a potential therapeutic target and biomarker for breast cancer progression.

Deregulation of Wnt/ß-catenin signaling through genetic or epigenetic alterations in human neuroendocrine tumors.

Carcinoid tumors are rare neuroendocrine tumors (NETs) that are increasing in incidence. Mutation and altered expression of Wnt/ß-catenin signaling components have been described in many tumors but have not been well-studied in NETs. Here, we observed accumulation of ß-catenin in the cytoplasm and/or nucleus in 25% of clinical NET tissues. By mutational analysis, the mutations of ß-catenin (I35S) and APC (E1317Q, T1493T) were identified in NET cells and the tissues. Expression of representative Wnt inhibitors was absent or markedly decreased in BON, a human pancreatic carcinoid cell line; treatment with 5-aza-2'-deoxycytidine (5-aza-CdR) increased expression levels of the Wnt inhibitors. Methylation analyses demonstrated that CpG islands of SFRP-1 and Axin-2 were methylated, whereas the promoters of DKK-1, DKK-3 and WIF-1 were unmethylated in four NET cells. Aberrant methylation of SFRP-1 was particularly observed in most of clinical NET tissues. In addition, the repression of these unmethylated genes was associated with histone H3 lysine 9 dimethylation (H3K9me2) in BON cells. Together, 5-aza-CdR treatment inhibited cell proliferation and decreased the protein levels of H3K9me2 and G9a. Moreover, a novel G9a inhibitor, UNC0638, suppressed BON cell proliferation through inhibition of Wnt/ß-catenin pathway. Overexpression of the inhibitory genes, particularly SFRP-1 and WIF-1 in BON cells, resulted in suppression of anchorage-independent growth and inhibition of tumor growth in mice. Our findings suggest that aberrant Wnt/ß-catenin signaling, through either mutations or epigenetic silencing of Wnt antagonists, contributes to the pathogenesis and growth of NETs and have important clinical implications for the prognosis and treatment of NETs.

Murine portal vein catheterization to analyze liver-directed therapies.

BACKGROUND: Small interfering RNA (siRNA) provides a highly selective method to target mutated pathways; however, its use is complicated by specific delivery to tumor cells. The aims of the present study were to develop a novel murine model of portal vein catheterization for the chronic delivery of therapeutic agents to liver metastases, determine the benefits of local delivery of siRNA to liver metastases, and determine the utility of epithelial cell adhesion molecule (EpCAM) as a selective target for siRNA delivery to colorectal cancer (CRC) metastases. MATERIALS AND METHODS: First, portal vein catheterization was performed through a midline laparotomy in 2 mo-old Balb/C mice. Second, the portal venous flow distribution and catheter patency were evaluated using fluorescent-labeled microspheres. Metastatic studies were performed by splenic injection of CT26 murine colon cancer cells. Uptake of DY-547-labeled siRNA was assessed by IVIS imaging, with delivery to the metastases confirmed using fluorescent microscopy. Finally, EpCAM expression was evaluated using immunohistochemical staining of human tissue microarrays. RESULTS: Successful portal vein catheterization was confirmed by saline injection and ultrasound. Fluorescent imaging of microspheres confirmed excellent distribution and catheter patency. Portal venous injection of DY547-labeled siRNA demonstrated a high level of fluorescence throughout the liver, with siRNA also identified within the liver metastases. Also, all primary CRCs and liver metastases stained strongly for EpCAM, with no expression in normal hepatocytes. CONCLUSIONS: Liver-directed therapy can provide the selective delivery of siRNA to CRC metastases. EpCAM expression in CRC, but not normal liver, could further selectively target hepatic metastases of epithelial origin.

Upregulation of CD36, a Fatty Acid Translocase, Promotes Colorectal Cancer Metastasis by Increasing MMP28 and Decreasing E-Cadherin Expression.

Altered fatty acid metabolism continues to be an attractive target for therapeutic intervention in cancer. We previously found that colorectal cancer (CRC) cells with a higher metastatic potential express a higher level of fatty acid translocase (CD36). However, the role of CD36 in CRC metastasis has not been studied. Here, we demonstrate that high expression of CD36 promotes invasion of CRC cells. Consistently, CD36 promoted lung metastasis in the tail vein model and GI metastasis in the cecum injection model. RNA-Seq analysis of CRC cells with altered expression of CD36 revealed an association between high expression of CD36 and upregulation of MMP28, a novel member of the metallopeptidase family of proteins. Using shRNA-mediated knockdown and overexpression of CD36, we confirmed that CD36 regulates MMP28 expression in CRC cells. siRNA-mediated knockdown of MMP28 decreases invasion of CRC cells, suggesting that MMP28 regulates the metastatic properties of cells downstream of CD36. Importantly, high expression of MMP28 leads to a significant decrease in active E-cadherin and an increase in the products of E-cadherin cleavage, CTF1 and CTF2. In summary, upregulation of CD36 expression promotes the metastatic properties of CRC via upregulation of MMP28 and an increase in E-cadherin cleavage, suggesting that targeting the CD36-MMP28 axis may be an effective therapeutic strategy for CRC metastasis.

Inhibition of aldose reductase prevents colon cancer metastasis.

Colon cancer is the third most common cause of cancer and is the second leading cause of cancer deaths in the USA. Although inhibition of aldose reductase (AR) is known to prevent human colon cancer cell growth in nude mice xenografts, the role of AR in the regulation of cancer metastasis is not known. We now demonstrate the mechanisms by which AR regulates colon cancer metastasis in vitro and in vivo. Inhibition of AR prevented the epidermal growth factor (EGF) or fibroblast growth factor (FGF)-induced migration and invasion of human colon cancer (HT29; KM20) cells by >70% and also inhibited (>80%) the adhesion of the cancer cells to endothelial cells. Treatment of endothelial cells with AR inhibitors significantly (∼85%) downregulated the EGF or FGF-induced expression of Inter-Cellular Adhesion Molecule-1, Vascular cell adhesion molecule-1 and vascular endothelial-cadherin. Furthermore, liver metastasis of green fluorescent protein-labeled KM20 cells injected into the spleen of athymic nude mice was significantly (>65%) prevented by AR inhibitor, fidarestat or ARsiRNA delivered systemically into the mice. Similar results were observed with HT29 cells. AR inhibition or ablation also prevented (70-90%) the increase in the levels of matrix metalloproteinase-2, cyclin D1, CD31, CD34 and the activation of nuclear factor-kappa-binding protein in metastatic liver. Thus, our results indicate that AR regulates cancer cell adhesion, invasion and migration events which initiate metastasis and therefore, AR inhibition could be a novel therapeutic approach for the prevention of colon cancer metastasis.

VEGFR-2 expression in carcinoid cancer cells and its role in tumor growth and metastasis.

Carcinoid tumors are slow growing and highly vascular neuroendocrine neoplasms that are increasing in incidence. Previously, we showed that carcinoid tumors express vascular endothelial growth factor receptor 2 (VEGFR-2) in the epithelial compartment of carcinoid tumor sections; yet, its role is not completely understood. The purpose of our study was to: (i) assess the expression of VEGFR-2 in the novel human carcinoid cell line BON, (ii) to determine the role of PI3K/Akt signaling on VEGFR-2 expression and (iii) to assess the effect of VEGFR-2 on BON cell invasion, migration and proliferation. We found that, although VEGFR-2 is expressed in BON cells, reduction in VEGFR-2 expression actually enhanced proliferation, invasion, and migration of the BON cell line. Also, expression of VEGFR-2 was inversely related to PI3K signaling. Carcinoid liver metastases in mice demonstrated decreased VEGFR-2 expression. Furthermore, the expression of a truncated, soluble form of VEGFR-2 (sVEGFR-2), a protein demonstrated to inhibit cell growth, was detected in BON cells. The presence of VEGFR-2 in the epithelial component of carcinoid tumors and in the BON cell line suggests an alternate role for VEGFR-2, in addition to its well-defined role in angiogenesis. The expression of sVEGFR-2 may explain the inverse relationship between VEGFR-2 expression and PI3K/Akt signaling and the inhibitory effect VEGFR-2 has on BON cell proliferation, migration and invasion.

Gastrin-releasing peptide receptor silencing suppresses the tumorigenesis and metastatic potential of neuroblastoma.

Neuroblastoma accounts for nearly 15% of all pediatric cancer-related deaths. We have previously shown that gastrin-releasing peptide (GRP) stimulates neuroblastoma growth, and that its cell surface receptor, GRP-R, is overexpressed in advanced-stage human neuroblastomas; however, the effects of GRP/GRP-R on tumorigenesis and metastasis in vivo are not clearly elucidated. In the present study, we found that GRP-R knockdown in the aggressive cell line BE(2)-C induced cell morphology changes, reduced cell size, decreased cell proliferation, and inhibited DNA synthesis, corresponding to cell cycle arrest at G(2)/M phase. Activated Akt, a crucial regulator of cell survival and metastasis, was down-regulated by GRP-R silencing. In addition, expression of p-p70S6K and its downstream target molecule S6, key regulators of protein synthesis and cell metabolism, were also significantly decreased by GRP-R silencing. GRP-R knockdown also up-regulated the expression of tumor suppressor PTEN, the inhibitor of the PI3K/Akt pathway. Furthermore, silencing GRP-R as well as GRP in BE(2)-C cells suppressed anchorage-independent growth in vitro. Conversely, overexpression of GRP-R in less aggressive SK-N-SH neuroblastoma cells resulted in soft agar colony formation, which was inhibited by a GRP-blocking antibody. Moreover, GRP-R deficiency significantly delayed tumor growth and diminished liver metastases in vivo. Our findings demonstrate that GRP and GRP-R have important oncogenic properties beyond their established mitogenic functions. Therefore, GRP-R may be an ideal therapeutic target for the treatment of aggressive neuroblastomas.

Akt2 overexpression plays a critical role in the establishment of colorectal cancer metastasis.

Colorectal cancer is the second leading cause of cancer-related deaths in the United States. Understanding the distinct genetic and epigenetic changes contributing to the establishment and growth of metastatic lesions is crucial for the development of novel therapeutic strategies. In a search for key regulators of colorectal cancer metastasis establishment, we have found that the serine/threonine kinase Akt2, a known proto-oncogene, is highly expressed in late-stage colorectal cancer and metastatic tumors. Suppression of Akt2 expression in highly metastatic colorectal carcinoma cells inhibits their ability to metastasize in an experimental liver metastasis model. Overexpression of wild-type Akt1 did not restore metastatic potential in cells with downregulated Akt2, thus suggesting non-redundant roles for the individual Akt isoforms. In contrast, Akt2 overexpression in wild-type PTEN expressing SW480 colorectal cancer cells led to the formation of micrometastases; however, loss of PTEN is required for sustained formation of overt metastasis. Finally, we found that the consequence of PTEN loss and Akt2 overexpression function synergistically to promote metastasis. These results support a role for Akt2 overexpression in metastatic colorectal cancer and establish a mechanistic link between Akt2 overexpression and PTEN mutation in metastatic tumor establishment and growth. Taken together, these data suggest that Akt family members have distinct functional roles in tumor progression and that selective targeting of the PI3K/Akt2 pathway may provide a novel treatment strategy for colorectal cancer metastasis.

Development and characterization of a novel in vivo model of carcinoid syndrome.

PURPOSE: Carcinoid syndrome, characterized by flushing, diarrhea, and valvular heart disease, can occur following carcinoid tumor metastasis to the liver and systemic release of bioactive hormones into the systemic circulation. Treatment of this devastating disease is hampered by the lack of an in vivo model that recapitulates the clinical syndrome. EXPERIMENTAL DESIGN: Here, we have injected BON cells, a novel human carcinoid cell line established in our laboratory, into the spleens of athymic nude mice to establish liver metastases. RESULTS: The majority of mice injected intrasplenically with BON cells developed significant increases in plasma serotonin and urine 5-hydroxyindoleacetic acid, and several mice exhibited mesenteric fibrosis, diarrhea, and fibrotic cardiac valvular disease reminiscent of carcinoid syndrome by both echocardiographic and histopathologic evaluation. Mice pretreated with octreotide, a long-acting somatostatin analogue, or bevacizumab, a vascular endothelial growth factor inhibitor, developed fewer liver metastases and manifestations of carcinoid syndrome, including valvular heart disease. CONCLUSION: We have provided an important in vivo model to further delineate novel treatment modalities for carcinoid syndrome that will also be useful to elucidate the factors contributing to the sequelae of carcinoid disease (e.g., mesenteric fibrosis and valvular heart disease).

Inhibition of Fatty Acid Synthase Upregulates Expression of CD36 to Sustain Proliferation of Colorectal Cancer Cells.

Fatty acid synthase, a key enzyme of de novo lipogenesis, is an attractive therapeutic target in cancer. The novel fatty acid synthase inhibitor, TVB-3664, shows anti-cancer activity in multiple cancers including colorectal cancer; however, it is unclear whether uptake of exogeneous fatty acids can compensate for the effect of fatty acid synthase inhibition. This study demonstrates that inhibition of fatty acid synthase selectively upregulates fatty acid translocase (CD36), a fatty acid transporter, in multiple colorectal cancer models including colorectal cancer cells with shRNA mediated knockdown of fatty acid synthase and genetically modified mouse tissues with heterozygous and homozygous deletion of fatty acid synthase. Furthermore, human colorectal cancer tissues treated with TVB-3664 show a significant and selective upregulation of CD36 mRNA. shRNA-mediated knockdown of CD36 and inhibition of CD36 via sulfosuccinimidyl oleate, a chemical inhibitor of CD36, decreased cell proliferation in vitro and reduced tumor growth in subcutaneous xenograft models. Isogenic cell populations established from patient derived xenografts and expressing high levels of CD36 show a significantly increased ability to grow tumors in vivo. The tumor-promoting effect of CD36 is associated with an increase in the levels of pAkt and survivin. Importantly, combinatorial treatment of primary and established colorectal cancer cells with TVB-3664 and sulfosuccinimidyl oleate shows a synergistic effect on cell proliferation. In summary, our study demonstrates that upregulation of CD36 expression is a potential compensatory mechanism for fatty acid synthase inhibition and that inhibition of CD36 can improve the efficacy of fatty acid synthase-targeted therapy.

Novel cross talk of Kruppel-like factor 4 and beta-catenin regulates normal intestinal homeostasis and tumor repression.

Epithelial cells of the intestinal mucosa undergo a continual process of proliferation, differentiation, and apoptosis which is regulated by multiple signaling pathways. The Wnt/beta-catenin pathway plays a critical role in this process. Mutations in the Wnt pathway, however, are associated with colorectal cancers. Krüppel-like factor 4 (KLF4) is an epithelial transcriptional factor that is down-regulated in many colorectal cancers. Here, we show that KLF4 interacts with beta-catenin and represses beta-catenin-mediated gene expression. Moreover, KLF4 inhibits the axis formation of Xenopus embryos and inhibits xenograft tumor growth in athymic nude mice. Our findings suggest that the cross talk of KLF4 and beta-catenin plays a critical role in homeostasis of the normal intestine as well as in tumorigenesis of colorectal cancers.

Novel chemotherapeutic agent, FND-4b, activates AMPK and inhibits colorectal cancer cell proliferation.

Colorectal cancer (CRC) is the second leading cause of cancer deaths in the US with the majority of deaths due to metastatic disease. Current chemotherapeutic regimens involve highly toxic agents, which limits their utility; therefore, more effective and less toxic agents are required to see a reduction in CRC mortality. Novel fluorinated N,N'-diarylureas (FND) were developed and characterized by our group as potent activators of adenosine monophosphate-activated kinase (AMPK) that inhibit cell cycle progression. The purpose of this study was to determine the effect of a lead FND compound, FND-4b, either alone or combined with PI-103 (a dual PI3K/mTOR inhibitor) or SN-38 (active metabolite of irinotecan) on cell cycle arrest and apoptosis of CRC cell lines (both commercially-available and novel lines established from our patient population). Treatment with FND-4b for 24h resulted in a marked induction of phosphorylated AMPK expression and a concomitant reduction in markers of cell proliferation, such as cyclin D1, in all CRC cell lines. Apoptosis was also notably increased in CRC cells treated with FND-4b. Regardless of the genetic profile of the CRC cells, FND-4b treatment alone resulted in decreased cell proliferation. Moreover, the combination of FND-4b with PI-103 resulted in increased cell death in all cell lines, while the combination of FND-4b with SN-38 resulted in increased cell death in select cell lines. Our findings identify FND-4b, which activates AMPK at micromolar concentrations, as a novel and effective inhibitor of CRC growth either alone or in combination with PI-103 and SN-38.

Preclinical evaluation of novel fatty acid synthase inhibitors in primary colorectal cancer cells and a patient-derived xenograft model of colorectal cancer.

Fatty Acid Synthase (FASN), a key enzyme of de novo lipogenesis, is upregulated in many cancers including colorectal cancer (CRC); increased FASN expression is associated with poor prognosis. Potent FASN inhibitors (TVBs) developed by 3-V Biosciences demonstrate anti-tumor activity in vitro and in vivo and a favorable tolerability profile in a Phase I clinical trial. However, CRC characteristics associated with responsiveness to FASN inhibition are not fully understood. We evaluated the effect of TVB-3664 on tumor growth in nine CRC patient-derived xenografts (PDXs) and investigated molecular and metabolic changes associated with CRC responsiveness to FASN inhibition. CRC cells and PDXs showed a wide range of sensitivity to FASN inhibition. TVB-3664 treatment showed significant response (reduced tumor volume) in 30% of cases. Anti-tumor effect of TVB-3664 was associated with a significant decrease in a pool of adenine nucleotides and alterations in lipid composition including a significant reduction in fatty acids and phospholipids and an increase in lactosylceramide and sphingomyelin in PDXs sensitive to FASN inhibition. Moreover, Akt, Erk1/2 and AMPK were major oncogenic pathways altered by TVBs. In summary, we demonstrated that novel TVB inhibitors show anti-tumor activity in CRC and this activity is associated with a decrease in activation of Akt and Erk1/2 oncogenic pathways and significant alteration of lipid composition of tumors. Further understanding of genetic and metabolic characteristics of tumors susceptible to FASN inhibition may enable patient selection and personalized medicine approaches in CRC.

PTHrP increases xenograft growth and promotes integrin alpha6beta4 expression and Akt activation in colon cancer.

Parathyroid hormone-related protein (PTHrP) is expressed by human colon cancer tissue and cell lines. Expression of PTHrP and phosphatidylinositol 3-kinase (PI3-K) pathway components correlates with the severity of colon carcinoma. Here we observed a positive effect of endogenous PTHrP on LoVo (human colon cancer) cell proliferation, migration, invasion, integrin alpha6 and beta4 expression, and p-Akt levels. There was a direct correlation between PTHrP expression and anchorage-independent cell growth. PTHrP significantly increased xenograft growth; tumors from PTHrP-overexpressing cells showed increased expression of integrins alpha6 and beta4, and PI3-K pathway components. The higher expression of PTHrP in human colon cancer adenocarcinoma vs. normal colonic mucosa was accompanied by increased integrin alpha6 and beta4 levels. Elevated PTHrP expression in colon cancer may thus upregulate integrin alpha6beta4 expression, with consequent PI3-K activation. Targeting PTHrP might result in effective inhibition of tumor growth, migration, and invasion.

Bombesin induces angiogenesis and neuroblastoma growth.

Gastrin-releasing peptide (GRP), the mammalian equivalent of bombesin (BBS), is a trophic factor for highly vascular neuroblastomas; its mechanisms of action in vivo are unknown. We sought to determine the effects of BBS on the growth of neuroblastoma xenografts and on angiogenesis. BBS significantly increased the growth of SK-N-SH and BE(2)-C human neuroblastomas; tumors demonstrated increased expression of angiogenic markers, PECAM-1 and VEGF, as well as phosphorylated (p)-Akt levels. RC-3095, a BBS/GRP antagonist, attenuated BBS-stimulated tumor growth and angiogenesis in vivo. GRP or GRPR silencing significantly inhibited VEGF as well as p-Akt and p-mTOR expression in vitro. Our findings demonstrate that BBS stimulates neuroblastoma growth and the expression of angiogenic markers. Importantly, these findings suggest that novel therapeutic agents, targeting BBS-mediated angiogenesis, may be useful adjuncts in patients with advanced-stage neuroblastomas.

Effectiveness of siRNA uptake in target tissues by various delivery methods.

BACKGROUND: RNA interference offers clinical potential as a therapeutic modality for a variety of diseases; the efficacy of in vivo delivery remains poorly understood. The purpose of our study was to compare and contrast short interfering RNA (siRNA) uptake in vivo using various delivery techniques. METHODS: DY547- and rhodamine-labeled siRNA was administered to mice by one of four delivery methods: (1) hydrodynamic intravenous tail vein injection, (2) standard intravenous tail vein injection, (3) intraperitoneal injection, and (4) rectal administration. Mice were killed over a time course; representative tissue samples were collected and analyzed using fluorescent microscopy to determine siRNA uptake. RESULTS: siRNA uptake was noted in the liver, kidney, pancreas, spleen, and bone marrow by both hydrodynamic and standard IV injection. siRNA uptake was detected in the spleen, liver, and bone marrow after intraperitoneal administration. Rectal administration resulted in siRNA uptake in the spleen, bone marrow, and colon. CONCLUSION: Our results demonstrate differential siRNA uptake depending on delivery technique. Importantly, our results demonstrate the potential of siRNA as a systemic therapeutic option in vivo for selected disease processes.

Phosphatidylinositol 3-kinase pathway regulates hypoxia-inducible factor-1 to protect from intestinal injury during necrotizing enterocolitis.

BACKGROUND: Hypoxia is an important risk factor for development of necrotizing enterocolitis (NEC) in premature infants. Hypoxia-inducible factor (HIF)-1 is a transcription factor that plays a critical role in cellular responses to hypoxia and can be induced by phosphatidylinositol 3-kinase (PI3-K) pathway. Activation of the PI3-K and regulation of HIF-1 during NEC have not been elucidated. METHODS: NEC was induced in 3-day-old neonatal mice using hypoxia and artificial formula feedings. Mice were divided into 3 treatment groups: (1) NEC alone, (2) NEC with insulin-like growth factor (IGF)-I, or (3) NEC with Akt1 siRNA treatment. Animals were sacrificed, and intestinal sections were harvested for protein analysis, H&E, and immunohistochemical staining. RESULTS: In vivo model of NEC produced intestinal injury associated with increased protein expression of HIF-1alpha, pAkt, PARP, and caspase-3 cleavage. Pretreatment with IGF-1 attenuated an HIF-1alpha response. In contrast, targeted inhibition of Akt1 completely abolished NEC-induced expression of pAkt and upregulated HIF-1alpha activation. CONCLUSIONS: NEC activates important protective cellular responses to hypoxic injury such as HIF-1alpha and PI3-K/Akt in neonatal gut. Hypoxia-mediated activation of pro-survival signaling during NEC may be modulated with growth factors, which thus suggests a potential therapeutic option in the treatment of neonates with NEC.