Stimulation of calcium influx and CK1α by NF-κB antagonist [6]-Gingerol reprograms red blood cell longevity

Chemotherapy-induced anemia (CIA) is a major obstacle in cancer management. Although the mechanisms governing CIA are poorly understood, recent efforts have identified suicidal erythrocyte (red blood cell, RBC) death as a possible cause of CIA. [6]-Gingerol (GNG), a polyphenol extracted from Zingiber officinale plant, exhibits a wide array of biological activities including antimicrobial, antioxidant, anti-inflammatory, immunomodulatory, and anticancer activities, in vitro and in vivo. However, the potential toxicity of GNG to human RBCs remains unexplored. RBCs from heparinized blood were isolated by centrifugation and exposed to antitumor concentrations (10-100 µM) of GNG for 24 hr at 37°C. Hemolysis was calculated from hemoglobin leakage in the supernatant (λ_max  = 405 nm), while cytofluorometric analysis of eryptosis employed Annexin-V-FITC to detect phosphatidylserine (PS) exposure, forward scatter (FSC) to estimate cell volume, Fluo4/AM to measure calcium activity, and H₂ DCFDA to assess oxidative stress. Moreover, zVAD(OMe)-FMK, SB203580, necrostatin-2, staurosporin, and D4476 were used to identify signaling pathways responsive to GNG. GNG induced significant hemolysis at 100 µM, independently of extracellular calcium, and increased Annexin-V-FITC fluorescence that was thoroughly abrogated without extracellular calcium. GNG also enhanced Fluo4 fluorescence and reduced FSC, but had no significant effect on DCF fluorescence. Importantly, the presence of D4476 significantly attenuated GNG-induced hemolysis. In conclusion, GNG stimulates premature RBC death characterized by loss of membrane asymmetry, elevated cytosolic calcium, cell shrinkage, and casein kinase 1α activation. Blocking the activity of calcium channels or CK1α may, therefore, ameliorate the toxic effects of GNG on RBCs. PRACTICAL APPLICATIONS: This report presents a safety assessment of GNG as a chemotherapeutic agent and highlights the novel toxicity of GNG to human RBCs. Our findings provide novel insights that may lead to more efficient utilization of GNG in chemotherapy. Specifically, our data revealed the involvement of calcium channels and casein kinase 1α in mediating GNG-induced premature RBC death, and, therefore, inverse agonists or inhibitors of either pathway may be used as pharmaceutical adjuvants to attenuate the toxic effects of GNG.

Free fatty acids receptors 2 and 3 control cell proliferation by regulating cellular glucose uptake

BACKGROUND

Colorectal cancer (CRC) is a worldwide problem, which has been associated with changes in diet and lifestyle pattern. As a result of colonic fermentation of dietary fibres, short chain free fatty acids are generated which activate free fatty acid receptors (FFAR) 2 and 3. FFAR2 and FFAR3 genes are abundantly expressed in colonic epithelium and play an important role in the metabolic homeostasis of colonic epithelial cells. Earlier studies point to the involvement of FFAR2 in colorectal carcinogenesis.

AIM

To understand the role of short chain FFARs in CRC.

METHODS

Transcriptome analysis console software was used to analyse microarray data from CRC patients and cell lines. We employed short-hairpin RNA mediated down regulation of FFAR2 and FFAR3 genes, which was validated using quantitative real time polymerase chain reaction. Assays for glucose uptake and cyclic adenosine monophosphate (cAMP) generation was done along with immunofluorescence studies to study the effects of FFAR2/FFAR3 knockdown. For measuring cell proliferation, we employed real time electrical impedance-based assay available from xCELLigence.

RESULTS

Microarray data analysis of CRC patient samples showed a significant down regulation of FFAR2 gene expression. This prompted us to study the FFAR2 in CRC. Since, FFAR3 shares significant structural and functional homology with FFAR2, we knocked down both these receptors in CRC cell line HCT 116. These modified cell lines exhibited higher proliferation rate and were found to have increased glucose uptake as well as increased level of glucose transporter 1. Since, FFAR2 and FFAR3 signal through G protein subunit (Gαi), knockdown of these receptors was associated with increased cAMP. Inhibition of protein kinase A (PKA) did not alter the growth and proliferation of these cells indicating a mechanism independent of cAMP/PKA pathway.

CONCLUSION

Our results suggest role of FFAR2/FFAR3 genes in increased proliferation of colon cancer cells via enhanced glucose uptake and exclude the role of PKA mediated cAMP signalling. Alternate pathways could be involved that would ultimately result in increased cell proliferation as a result of down regulated FFAR2/FFAR3 genes. This study paves the way to understand the mechanism of action of short chain FFARs in CRC.

IGFBP7 Deletion Promotes Hepatocellular Carcinoma

Activation of IGF signaling is a major oncogenic event in diverse cancers, including hepatocellular carcinoma (HCC). In this setting, the insulin-like growth factor binding protein IGFBP7 inhibits IGF signaling by binding the IGF1 receptor (IGF1R), functioning as a candidate tumor suppressor. IGFBP7 abrogates tumors by inhibiting angiogenesis and inducing cancer-specific senescence and apoptosis. Here, we report that Igfbp7-deficient mice exhibit constitutively active IGF signaling, presenting with proinflammatory and immunosuppressive microenvironments and spontaneous liver and lung tumors occurring with increased incidence in carcinogen-treated subjects. Igfbp7 deletion increased proliferation and decreased senescence of hepatocytes and mouse embryonic fibroblasts, effects that were blocked by treatment with IGF1 receptor inhibitor. Significant inhibition of genes regulating immune surveillance was observed in Igfbp7^-/- murine livers, which was associated with a marked inhibition in antigen cross-presentation by Igfbp7^-/- dendritic cells. Conversely, IGFBP7 overexpression inhibited growth of HCC cells in syngeneic immunocompetent mice. Depletion of CD4⁺ or CD8⁺ T lymphocytes abolished this growth inhibition, identifying it as an immune-mediated response. Our findings define an immune component of the pleiotropic mechanisms through which IGFBP7 suppresses HCC. Furthermore, they offer a genetically based preclinical proof of concept for IGFBP7 as a therapeutic target for immune management of HCC. Cancer Res; 77(15); 4014-25. ©2017 AACR.

Abstract 3823: Staphylococcal nuclease and tudor domain containing 1 (SND1) in development and progression of hepatocellular carcinoma

Staphylococcal nuclease and tudor domain containing 1 (SND1) is identified as an oncogene in hepatocellular carcinoma (HCC) and overexpression of SND1 has been correlated with HCC progression. Here, we present effect of liver specific overexpression of human SND1 in a novel transgenic mouse model. We observe greater tumor load and tumor volume in transgenic mice than wildtype mice, when subjected to chemical carcinogenesis. Approximately 30% of transgenic animals manifest spontaneous tumorigenesis with age. Liver specific expression of cancer stem cell markers such as EpCAM and CD133 as well as inflammatory markers was found to be higher in transgenic mice. SND1 overexpressing hepatocytes show increased activation of insulin and NFκB signaling pathways compared to wildtype hepatocytes. However, no significant differences in liver weight or liver function was noted among transgenic and wildtype animals. Overall, our findings confirm that overexpression of SND1 in vivo plays a vital role in development and progression of HCC. Thus, molecular targeting of SND1 seems to be potential therapeutic intervention for HCC management in patients.

Citation Format: Nidhi Jariwala, Devaraja Rajasekaran, Rachel Gredler, Maaged Akiel, Chadia Robertson, Paul Fisher, Arun Sanyal, Devanand Sarkar. Staphylococcal nuclease and tudor domain containing 1 (SND1) in development and progression of hepatocellular carcinoma. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 3823.

Combination of Nanoparticle-Delivered siRNA for Astrocyte Elevated Gene-1 (AEG-1) and All-trans Retinoic Acid (ATRA): An Effective Therapeutic Strategy for Hepatocellular Carcinoma (HCC)

Hepatocellular carcinoma (HCC) is a fatal cancer with no effective therapy. Astrocyte elevated gene-1 (AEG-1) plays a pivotal role in hepatocarcinogenesis and inhibits retinoic acid-induced gene expression and cell death. The combination of a lentivirus expressing AEG-1 shRNA and all-trans retinoic acid (ATRA) profoundly and synergistically inhibited subcutaneous human HCC xenografts in nude mice. We have now developed liver-targeted nanoplexes by conjugating poly(amidoamine) (PAMAM) dendrimers with polyethylene glycol (PEG) and lactobionic acid (Gal) (PAMAM-PEG-Gal) which were complexed with AEG-1 siRNA (PAMAM-AEG-1si). The polymer conjugate was characterized by (1)H-NMR, MALDI, and mass spectrometry; and optimal nanoplex formulations were characterized for surface charge, size, and morphology. Orthotopic xenografts of human HCC cell QGY-7703 expressing luciferase (QGY-luc) were established in the livers of athymic nude mice and tumor development was monitored by bioluminescence imaging (BLI). Tumor-bearing mice were treated with PAMAM-siCon, PAMAM-siCon+ATRA, PAMAM-AEG-1si, and PAMAM-AEG-1si+ATRA. In the control group the tumor developed aggressively. ATRA showed little effect due to high AEG-1 levels in QGY-luc cells. PAMAM-AEG-1si showed significant reduction in tumor growth, and the combination of PAMAM-AEG-1si+ATRA showed profound and synergistic inhibition so that the tumors were almost undetectable by BLI. A marked decrease in AEG-1 level was observed in tumor samples treated with PAMAM-AEG-1si. The group treated with PAMAM-AEG-1si+ATRA nanoplexes showed increased necrosis, inhibition of proliferation, and increased apoptosis when compared to other groups. Liver is an ideal organ for RNAi therapy and ATRA is an approved anticancer agent. Our exciting observations suggest that the combinatorial approach might be an effective way to combat HCC.

Astrocyte Elevated Gene-1 (AEG-1) Regulates Lipid Homeostasis

Astrocyte elevated gene-1 (AEG-1), also known as MTDH (metadherin) or LYRIC, is an established oncogene. However, the physiological function of AEG-1 is not known. To address this question, we generated an AEG-1 knock-out mouse (AEG-1KO) and characterized it. Although AEG-1KO mice were viable and fertile, they were significantly leaner with prominently less body fat and lived significantly longer compared with wild type (WT). When fed a high fat and cholesterol diet (HFD), WT mice rapidly gained weight, whereas AEG-1KO mice did not gain weight at all. This phenotype of AEG-1KO mice is due to decreased fat absorption from the intestines, not because of decreased fat synthesis or increased fat consumption. AEG-1 interacts with retinoid X receptor (RXR) and inhibits RXR function. In enterocytes of AEG-1KO mice, we observed increased activity of RXR heterodimer partners, liver X receptor and peroxisome proliferator-activated receptor-α, key inhibitors of intestinal fat absorption. Inhibition of fat absorption in AEG-1KO mice was further augmented when fed an HFD providing ligands to liver X receptor and peroxisome proliferator-activated receptor-α. Our studies reveal a novel role of AEG-1 in regulating nuclear receptors controlling lipid metabolism. AEG-1 may significantly modulate the effects of HFD and thereby function as a unique determinant of obesity.

Abstract 72: Analyzing the role of Astrocyte Elevated Gene-1 (AEG-1) in hepatocarcinogenesis using a knockout mouse model

The oncogene Astrocyte Elevated Gene-1 (AEG-1) is overexpressed in a wide variety of human cancers. In vitro and in vivo nude mouse xenograft studies have established the tumor-promoting role of AEG-1. Activation of multiple signaling pathways, such as NF-κB, PI3K/Akt, Wnt/β-catenin and MEK/ERK, has been attributed to mediate oncogenesis by AEG-1. To better understand the role AEG-1 plays in the onset and progression of cancer and to identify key mechanism(s) of AEG-1 action, we generated a novel AEG-1 knockout mouse (AEG-1-/-). We studied hepatocarcinogenesis in this model because AEG-1 is overexpressed in more than 90% of human hepatocellular carcinoma (HCC) patients and is believed to play a key regulatory role in progression of the disease. AEG-1-/- mice were viable with normal development. We first compared the aging associated phenotype of WT and AEG-1-/- mice. At 16 months of age spontaneous tumor development in lungs and liver was observed in some cohorts of untreated WT mice (n=20). Such tumorigenesis was not detected in any of the AEG-1-/- mice. Additionally, age-associated inflammatory infiltrates were observed in the internal organs of WT but not AEG-1-/- mice. To initiate HCC, WT and AEG-1-/- mice were treated with diethylnitrosamine (DEN) at 2 weeks of age. At 32 weeks WT mice showed a marked hepatocarcinogenic response while AEG-1-/- mice exhibited profound resistance to tumor formation. The hepatocarcinogenic response was further evaluated by DEN initiation followed by daily phenobarbital treatment. WT mice exhibited an intensified hepatocarcinogenic response evidenced by large necrotic liver tumors at 28 weeks of age with a 52% rate of lung metastasis. AEG-1-/- mice remained remarkably resistant even to this combinatorial treatment with no distant metastasis. No difference in the activation of Akt, ERK and β-catenin signaling was observed between WT and AEG-1-/- mice indicating that these pathways may not be regulated by AEG-1 under physiological conditions. However, marked inhibition of NF-κB activation was observed in AEG-1-/- mice. Lipopolysaccharide (LPS)-induced NF-κB luciferase reporter activity, nuclear translocation of p65 subunit of NF-κB and induction of IL-1β and IL-6 were markedly attenuated in primary hepatocytes and macrophages isolated from AEG-1-/- versus WT mice. Chronic inflammation and NF-κB activation play a causal role in hepatocarcinogenesis. Inhibition of NF-κB activation in hepatocytes and macrophages profoundly abrogates HCC development in mouse models. Our findings in AEG-1-/- mice confirm a fundamental role of AEG-1 in NF-κB activation. Here we demonstrate that lack of AEG-1 protects from generalized inflammation thereby suppressing spontaneous as well as experimental tumorigenesis. AEG-1-/-mice might be a useful model to study inflammation and cancer in diverse organ systems.

Citation Format: Chadia L. Robertson, Jyoti Srivastava, Ayesha Siddiq, Rachel Gredler, Devaraja Rajasekaran, Maaged Akiel, Xue-Ning Shen, Knarik Arkun, Shobha Ghosh, Mark A. Subler, Jolene Windle, Paul B. Fisher, Devanand Sarkar. Analyzing the role of Astrocyte Elevated Gene-1 (AEG-1) in hepatocarcinogenesis using a knockout mouse model. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 72. doi:10.1158/1538-7445.AM2014-72

Genetic deletion of AEG-1 prevents hepatocarcinogenesis

Activation of the oncogene AEG-1 (MTDH, LYRIC) has been implicated recently in the development of hepatocellular carcinoma (HCC). In mice, HCC can be initiated by exposure to the carcinogen DEN, which has been shown to rely upon activation of NF-κB in liver macrophages. Because AEG-1 is an essential component of NF-κB activation, we interrogated the susceptibility of mice lacking the AEG-1 gene to DEN-induced hepatocarcinogenesis. AEG-1-deficient mice displayed resistance to DEN-induced HCC and lung metastasis. No difference was observed in the response to growth factor signaling or activation of AKT, ERK, and β-catenin, compared with wild-type control animals. However, AEG-1-deficient hepatocytes and macrophages exhibited a relative defect in NF-κB activation. Mechanistic investigations showed that IL6 production and STAT3 activation, two key mediators of HCC development, were also deficient along with other biologic and epigenetics findings in the tumor microenvironment, confirming that AEG-1 supports an NF-κB-mediated inflammatory state that drives HCC development. Overall, our findings offer in vivo proofs that AEG-1 is essential for NF-κB activation and hepatocarcinogenesis, and they reveal new roles for AEG-1 in shaping the tumor microenvironment for HCC development.

Staphylococcal nuclease domain containing-1 (SND1) promotes migration and invasion via angiotensin II type 1 receptor (AT1R) and TGFβ signaling

Staphylococcal nuclease domain containing-1 (SND1) is overexpressed in human hepatocellular carcinoma (HCC) patients and promotes tumorigenesis by human HCC cells. We now document that SND1 increases angiotensin II type 1 receptor (AT1R) levels by increasing AT1R mRNA stability. This results in activation of ERK, Smad2 and subsequently the TGFβ signaling pathway, promoting epithelial-mesenchymal transition (EMT) and migration and invasion by human HCC cells. A positive correlation was observed between SND1 and AT1R expression levels in human HCC patients. Small molecule inhibitors of SND1, alone or in combination with AT1R blockers, might be an effective therapeutic strategy for late-stage aggressive HCC.

Emerging role of insulin-like growth factor-binding protein 7 in hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is a vicious and highly vascular cancer with a dismal prognosis. It is a life-threatening illness worldwide that ranks fifth in terms of cancer prevalence and third in cancer deaths. Most patients are diagnosed at an advanced stage by which time conventional therapies are no longer effective. Targeted molecular therapies, such as the multikinase inhibitor sorafenib, provide a modest increase in survival for advanced HCC patients and display significant toxicity. Thus, there is an immense need to identify novel regulators of HCC that might be targeted effectively. The insulin-like growth factor (IGF) axis is commonly abnormal in HCC. Upon activation, the IGF axis controls metabolism, tissue homeostasis, and survival. Insulin-like growth factor-binding protein 7 (IGFBP7) is a secreted protein of a family of low-affinity IGF-binding proteins termed “IGFBP-related proteins” that have been identified as a potential tumor suppressor in HCC. IGFBP7 has been implicated in regulating cellular proliferation, senescence, and angiogenesis. In this review, we provide a comprehensive discussion of the role of IGFBP7 in HCC and the potential use of IGFBP7 as a novel biomarker for drug resistance and as an effective therapeutic strategy.

Abstract 2628: The multifunctional protein staphylococcal nuclease domain containing-1 (SND1) promotes migration and invasion of hepatocellular carcinoma (HCC) cells by modulating angiotensin II type 1 receptor (AT1R) and transforming growth factor-β (TGF-β) s

Staphylococcal nuclease domain containing-1 (SND1) is a multifunctional protein that modulates transcription, mRNA splicing and stability, and miRNA function. We previously documented that SND1 is markedly overexpressed in human hepatocellular carcinoma (HCC) patients in a stage-specific manner and inhibition of SND1 in human HCC cells significantly abrogates in vitro proliferation and in vivo tumorigenesis in nude mice. In the present study we document that migration and invasion of human HCC cells are significantly augmented in SND1-overexpressing clones and significantly inhibited in SND1 shRNA-expressing clones. Differential gene expression analysis between control clone and SND1 shRNA expressing clones by Affymetrix microarray revealed downregulation of TGF-β downstream genes upon SND1 inhibition. Additionally, a human angiogenesis array identified plasminogen activator inhibitor-1 (PAI-1), a TGF-β downstream gene, to be upregulated by SND1 and this upregulation was confirmed by ELISA. TGF-β expression is regulated by angiotensin II type 1 receptors (AT1R) and previous studies have documented that SND1 increases AT1R expression by increasing AT1R mRNA stability. We hypothesized that increased AT1R expression, conferred by SND1 overexpression, might facilitate activation of TGF-β signaling and subsequently PAI-1-mediated increase in migration and invasion. Indeed, we observed that AT1R and TGF-β expression was significantly increased in SND1-overexpressing clones and decreased in SND1 knockdown clones. The half-life of AT1R mRNA was significantly longer in SND1-overexpressing clones compared to the control clone confirming that SND1 modulates AT1R post-transcriptionally. The AT1R blocker Losartan Potassium and AT1R siRNA significantly inhibited SND1-induced TGF-β and PAI-1 expression with associated inhibition in migration and invasion. As a corollary, inhibition of PAI-1 by siRNA significantly abrogated migration and invasion of SND1-overexpressing cells. TGF-β induces epithelial-mesenchymal transition (EMT) and we observed increased expression of EMT markers vimentin, snail and slug and decreased expression of E-cadherin in SND1-overexpressing clones and vice versa in SND1-knockdown clones. Our studies thus unravel a novel mechanism in which post-transcriptional regulation of AT1R by SND1, with subsequent activation of TGF-β signaling, promotes invasion of human HCC cells thereby conferring an aggressive phenotype. Small molecule inhibitors of SND1, thus, might be effective therapeutic strategy for late-stage aggressive HCC.

Citation Format: Prasanna K. Santhekadur, Rachel Gredler, Maaged Akiel, Paul Dent, Paul B. Fisher, Devanand Sarkar. The multifunctional protein staphylococcal nuclease domain containing-1 (SND1) promotes migration and invasion of hepatocellular carcinoma (HCC) cells by modulating angiotensin II type 1 receptor (AT1R) and transforming growth factor-β (TGF-β) s [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 2628. doi:10.1158/1538-7445.AM2013-2628