Adiponectin receptor agonists inhibit leptin induced pSTAT3 and in vivo pancreatic tumor growth

Obesity is a significant risk factor for pancreatic cancer, harboring a chronic inflammatory condition characterized by dysregulation of the adipokines, leptin and adiponectin, that in turn alter oncogenic signaling pathways. We and others have shown that leptin promotes the proliferation and an invasive potential of pancreatic cancer cells through STAT3 mediated signaling. However, the role of adiponectin on the tumorigenicity of pancreatic cancer has not been elucidated. Adiponectin represents an important negative regulator of cytokines, which acts through two receptors, ADIPOR1 and ADIPOR2, to elicit pro-apoptotic, anti-inflammatory, and anti-angiogenic responses. We show that the level and expression of both adiponectin receptors are decreased in pancreatic tumors relative to normal pancreatic tissue. In vitro stimulation with adiponectin or a small molecule adiponectin receptor agonist, AdipoRon, increases apoptosis while inhibiting pancreatic cancer cell proliferation, colony formation, and anchorage independent growth. In addition, adiponectin receptor agonism inhibits leptin mediated STAT3 activation. In vivo, treatment of mice with AdipoRon inhibits orthotopic pancreatic tumor growth. These results demonstrate that adiponectin receptor activation is a key regulator of pancreatic cancer growth and AdipoRon provides a rational agent for the development of novel therapeutic strategies for pancreatic cancer.

Abstract 2802: High fat diet increases development of hepatocellular carcinoma in glycine N-methyltransferase deficient mice

Introduction: Hepatocellular carcinoma (HCC) is the third leading cause of cancer deaths worldwide. HCC typically arises in patients with chronic liver disease or cirrhosis, yet it is increasingly associated with non-alcoholic fatty liver disease (NAFLD), specifically nonalcoholic steatohepatitis (NASH) in the absence of cirrhosis. NAFLD is associated with obesity, metabolic syndrome, and/or patients with type II diabetes. Our previous studies have shown that high fat diet induced hepatic steatosis increases proliferation of hepatocytes and the growth of malignant tumors in a murine model. Glycine N-MethylTransferase (GNMT) expression is lost in over 95% of HCC, and mice deficient in GNMT develop spontaneous HCC by 6 months of age. We hypothesized that GNMT deficient mice would have an increased susceptibility for the development and growth of HCC when a fed high fat diet.

Methods: Wildtype and GNMT deficient mice were placed on lean diet (LD, 13% calories from fat) or high fat diet (HFD, 42% calories from fat) at eight weeks of age. An initial cohort of mice were sacrificed after 3 months on diet (6 months of age) to assess for early tumor burden. A second cohort of mice was analyzed by magnetic resonance imaging (MRI) after 6 months on diet (9 months of age) and then sacrificed to assess for late stage disease. All mice were assessed for body weight, liver weight, pancreatic weight, and proliferative index (Ki67).

Results: GNMT deficient mice failed to gain weight when placed on HFD, which remained at levels equivalent to wildtype LD mice. At three months of age, wildtype mice on HFD had significantly enlarged livers due to hepatic steatosis. HFD fed GNMT deficient mouse livers were nearly 50% the size of wildtype livers and contained only minimal fatty deposits. Further, livers from HFD and LD fed GNMT mice were equivalent after 3 months, yet they were larger than wildtype mice fed LD. After six months on diet, MRI analysis showed significantly larger livers in HFD fed GNMT mice compared to LD fed GNMT mice due to extensive tumor burden. All wildtype mice lacked any tumors after six months regardless of diet. Histological analysis revealed a heightened cellular proliferation via Ki67 staining in GNMT deficient livers compared to wildtype livers. In comparison, GNMT silencing also occurs in pancreatic cancer, yet none of the GNMT deficient mice developed pancreatic tumors. However, small focal areas of pancreatitis were detected regardless of diet. Additionally, pancreatic weight was significantly decreased in HFD fed GNMT deficient mice compared the LD GNMT deficient mice.

Conclusions: While high fat diet did not induce obesity in GNMT deficient mice, it significantly increased cellular proliferation and primary tumor growth in the liver. Understanding dietary factors that impact the microenvironment of the liver and contribute to HCC development and progression is vital to finding new therapeutics for this malignancy.

Citation Format: Michael N. VanSaun, Alisha Mendonsa, Fanuel Messaggio, Nagaraj Nagathihalli, Lee Gorden. High fat diet increases development of hepatocellular carcinoma in glycine N-methyltransferase deficient mice [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 2802. doi:10.1158/1538-7445.AM2017-2802

Abstract A38: Adiponectin receptor agonists cause inhibition of pancreatic cancer proliferation

Adiponectin is an anti-atherogenic hormone which is typically decreased in the setting of obesity, diabetes, and pancreatitis. Adiponectin and/or its receptor levels have been inversely correlated with risk for pancreatic cancer. The purpose of this study was to determine the effect of adiponectin on pancreatic cancer cells and to investigate the primary molecular pathways that it regulates. We have previously shown that pancreatic cancer cells primarily produce adiponectin receptor 1. In our current studies, recombinant adiponectin and a novel small molecular adiponectin agonist, AdipoRon, were used to stimulate human and murine pancreatic cancer cell lines in vitro. Proliferation was assessed through an EdU incorporation assay, metabolism was measured through MTT, and apoptosis was assessed through Annexin V staining. Results demonstrate that adiponectin stimulation leads to a decrease in proliferation of pancreatic cancer cells. Further, AdipoRon elicits a more potent suppression of proliferation and an additional increase in apoptosis. To better understand the molecular mechanisms activated by adiponectin stimulation, we performed western blot analysis of treated cells. We were able to confirm that AMPK was a direct target of both adiponectin and AdipoRon. Further, we were able to show that FBS stimulated phosphorylation of Akt was diminished in the presence of AdipoRon. Our data demonstrate that adiponectin and adiponectin receptor agonists act in a suppressive manner against pancreatic cancer cell proliferation. Current studies will determine whether adiponectin agonists can additionally decrease proliferation in vivo.

Citation Format: Alisha Mendonsa, Lee Gorden, Michael Nathan VanSaun. Adiponectin receptor agonists cause inhibition of pancreatic cancer proliferation. [abstract]. In: Proceedings of the AACR Special Conference on Pancreatic Cancer: Innovations in Research and Treatment; May 18-21, 2014; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2015;75(13 Suppl):Abstract nr A38.

Abstract 4984: Contribution of MMP13 to tumor development in the steatotic liver microenvironment

With the rising prevalence of obesity there has been a marked increase in the incidence of non alcoholic fatty liver disease (NAFLD). Epidemiologically, NAFLD has been linked to an increased risk for development of primary liver cancer (HCC), however the mechanisms involved are not known. The liver is also a frequent site of metastasis for several types of cancers. To determine the effect of steatosis (fatty liver) on tumor metastasis to the liver, we used a mouse model of diet induced steatosis coupled with the splenic injection model of metastasis to the liver and found a significant increase in the number of tumors in the steatotic livers. To evaluate what molecular changes distinguish the steatotic liver from normal liver, microarray analysis was performed and demonstrated that MMP13, a member of the Matrix Metalloproteinase family recognized to be involved in liver disease and cancer progression, is significantly upregulated in the steatotic liver compared to normal livers of mice. We evaluated MMP13 expression in human patients with NAFLD and found that MMP13 is elevated with the progression of NAFLD. We hypothesize that increased MMP13 levels in the steatotic liver contribute to a more permissive microenvironment for the establishment of liver tumors. To test this hypothesis, mice genetically deficient in MMP13 or control wildtype mice, with and without steatosis, were injected with syngeneic MC38 colon cancer cells. Examination of the two groups demonstrated a significant decrease in the number of tumors in the MMP13 null mice (P <0.01). Additionally, since the tumor cells themselves express MMP13, wildtype mice were injected with either shRNA control or MMP13 knockdown MC38 colon cancer cells to determine the role of tumor cell derived MMP13. Using transwell migration assay and the platypus invasion system with parental and MMP13 shRNA knockdown MC38 cells we found that loss of MMP13 decreases the invasive and migratory properties of the metastatic cancer cells in vitro. In conclusion, we found that MMP13 is elevated in the setting of steatosis and that loss of both stromal and tumor derived MMP13 lead to decreased number of metastatic foci in the liver. Tumor derived MMP13 effects tumor cell migration and invasion invitro. MMP13 may thus be a potential target to control initiation and growth of metastatic cancer of the liver.

Citation Format: Alisha Maria Mendonsa, Michael N. VanSaun, Lee Gorden. Contribution of MMP13 to tumor development in the steatotic liver microenvironment. [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 4984. doi:10.1158/1538-7445.AM2014-4984

Abstract 299: Modulation of the leptin receptor in pancreatic cancer cells mediates tumor growth

Background: Pancreatic cancer is the fourth leading cause of cancer death with a five year survival rate around 5%, which has not changed in 30 years. Obesity and increased abdominal adipose tissue independently correlate with an increased relative risk for the development of pancreatic cancer. These conditions have been associated with altered levels of adipokines, or adipose secreted cytokines. Circulating serum levels of the adipokine leptin are increasesddramatically in obese patients as well as in high fat diet induced obese mice. Leptin has been shown to induce oncogenic signaling in breast and prostate cancer. We have previously shown an increase in orthotopic pancreatic tumor size in high fat diet induced obese mice compared with regular diet control mice. We hypothesize that leptin signaling mediates pancreatic tumorigenesis. Methods: Leptin receptor status was determined in human as well as murine pancreatic cell lines. Leptin stimulated cell proliferation was determined using a modified BrdU assay. Leptin receptor levels were knocked down in human and murine pancreatic tumor cells using a shRNAmir approach. Leptin receptor shRNA Panc02 knockdown cells were injected orthotopically into the pancreas of C57/Bl6J mice on regular or high fat diet to determine the contribution of leptin to pancreatic tumor growth. Results: We have detected the long form of the leptin receptor in five human and four murine pancreatic cancer cell lines. In vitro administration of leptin stimulated proliferation of Panc1 and CFPAC1 cell lines, which was abrogated with co-incubation of a leptin antagonist. To better understand the mechanism of leptin-mediated signaling, we studied downstream targets and identified a significant increase in phosphorylation of STAT3 in Panc1, BXPC3 and CFPAC1 cell lines after leptin treatment. Orhtotopic injection of leptin receptor shRNA Panc02 cells into normal and obese mice showed a markedly diminished tumor growth in obese mice when compared to the nonsilencing control Panc02 cell growth in obese mice. Conclusion: These results implicate leptin as a mediator of pancreatic tumorigenesis and suggest that leptin activation is mediated in part through STAT3 signaling. Knockdown of the leptin receptor results in inhibition of high fat diet associated tumor growth in vivo.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 299. doi:1538-7445.AM2012-299

Abstract 390: Increased orthotopic pancreatic tumor cell growth in obese mice

Pancreatic cancer remains one of the eight deadliest cancers due to its late detection and high propensity to metastasize. Increased risk for the development of pancreatic cancer has been associated with obesity, type II diabetes and pancreatitis. The contribution of adipocytes and adipokines to pancreatic cancer progression remains largely unknown and requires further analysis. We hypothesize that increased pancreatic fat compromises the pancreatic microenvironment and increases primary tumor growth as well as metastasis. The condition of non-alcoholic fatty pancreatic disease has been characterized in humans as well as mice and lymph node positive patients were found to have increased pancreatic fat1,2. Adipose secreted cytokines, also known as adipokines, have both been implicated in various aspects of cancer cell survival, growth, and migration. To understand the influence that increased pancreatic fat has on the growth of tumors, both primary and metastatic, we have investigated a high fat diet induced murine model. Male mice fed a 42% fat diet for three months develop increased inter-pancreatic and intra-pancreatic fat as well as acute localized pancreatitis when compared to mice fed a 13% fat diet. To test the affect of pancreatic fat on tumor cells, we used an orthotopic tumor injection model to determine the rate of primary tumor growth and progression to metastasis. Further, we are implementing the use of Panc02-luciferase tagged cells to monitor and measure pancreatic tumor growth over time and to detect the presence of metastases in the liver and/or lungs. Preliminary evidence has confirmed that orthotopic tumors grown in obese mice led to an increased tumor size as well as massive expansion of tumor cells into the interpancreatic fat. In conclusion, increased pancreatic fat promotes the growth of orthotopically implanted murine tumor cells, yet the molecular mechanisms remain undetermined.

1. Mathur, A. et al. J Am Coll Surg. 2009 May;208(5):989-94.

2. Mathur, A. et al. HPB (Oxford). 2007;9(4):312-8.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 390. doi:10.1158/1538-7445.AM2011-390

Cetuximab and circadian chronomodulated chemotherapy as salvage treatment for metastatic colorectal cancer (mCRC): safety, efficacy and improved secondary surgical resectability

BACKGROUND

Circadian rhythm disruption was linked to high serum levels of Transforming Growth Factor Receptor α, an Epidermal Growth Factor Receptor (EGFR) ligand and poor survival in patients with metastatic colorectal cancer (mCRC). We hypothesized that EGFR blockade with cetuximab would enhance the activity of chronotherapy as a result of improved circadian coordination.

METHODS

All the patients with mCRC referred to our unit for progression on prior chemotherapy over a 30-month-period received weekly cetuximab and fortnightly chronotherapy.

RESULTS

Fifty-six patients were treated with a median of six courses of fluoropyrimidine-based chemotherapy and irinotecan (61%), oxaliplatin (25%) or both (14%) after a median of three prior regimens. We found no EFGR amplification by FISH in the tumor of 27 consecutive patients. Acneiform rash and diarrhea were the most common toxicities. Objective response rate was 32.1% and positively correlated with rash grade (p = 0.025). None of the responders had K-Ras mutation in their tumor. Median progression-free and overall survival were 4.6 and 13.7 months, respectively. Complete macroscopic resections of metastases in liver, lung or other abdominopelvic sites were performed following tumor downstaging by the treatment regimen in 11 patients (21%), 8 of whom being alive at 3 years. These figures are twice as high as those reported for first-line combination of cetuximab with conventional chemotherapy or for third line chronotherapy.

CONCLUSIONS

The addition of cetuximab to chronotherapy allowed safe and effective therapeutic control of metastases, including their complete resection, despite previous failure of several treatment regimens.

Abstract LB-378: Establishment of hepatic metastases in a steatotic microenvironment is enhanced by stromal derived MMP-12

Non-alcoholic fatty liver disease (NAFLD), encompassing steatosis and progression to non-alcoholic steatohepatitis (NASH) are liver disorders of increasing clinical significance. We have shown that hepatic steatosis establishes a permissive microenvironment for metastatic seeding and tumor progression in the liver. We have identified MMP-12 (macrophage metalloelastase) as an important molecular component associated with hepatic steatosis and steatohepatitis. Wildtype mice in the C57Bl/6 background were fed a 42% fat diet for three months to induce hepatic steatosis. Affymetrix microarray analysis was performed on steatotic vs. normal murine livers to determine candidate genes altered between these liver microenvironments. Our results noted 715 significant changes in gene expression, of which matrix metalloproteinase 12 was among the most significantly up regulated genes in the steatotic microenvironment. Importantly, we have detected an upregulation of MMP-12 in human steatotic and steatohepatitis samples. MMP-12 deficient mice gained weight and developed diet-induced hepatic steatosis similar to wildtype mice. To determine whether MMP-12 affected metastasis, normal and steatotic MMP-12 deficient mice were tested with an experimental metastasis model via splenic injection of MC38 tumor cells. The number of resultant tumors per unit of tissue area in wildtype steatotic livers showed a 25 fold increase compared to tumors in MMP-12 deficient mice. Comparison of tumors between regular diet livers in wildtype and MMP12−/−mice was not significant. Immunohistochemical staining for F4/80 showed a reduction in the number of positive cells in MMP-12 deficient steatotic livers.

Conclusions: Modulation of host factors is known to be important in tissue/site specific susceptibility to cancer metastases. MMP-12 can influence immune-mediated injury response by processing latent TNF alpha and regulating macrophage recruitment. Upregulation of matrix metalloproteinase 12 suggest a role for this protease in inflammatory mediated events in the distinct microenvironments of steatosis and steatohepatitis. The molecular mechanisms underlying the decreased establishment of metastatic tumors in MMP-12 deficient mice requires further investigation.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr LB-378.

The Serum Glycoprotein Fetuin-A Promotes Lewis Lung Carcinoma Tumorigenesis via Adhesive-Dependent and Adhesive-Independent Mechanisms

Fetuin-A is a serum glycoprotein in the cystatin family associated with the regulation of soft tissue calcification. We tested the role of systemic fetuin in tumor cell growth and metastasis by injecting Lewis lung carcinoma (LLC) cells into fetuin-A null and their wild-type (WT) littermate control C57BL/6 mice via the tail vein, s.c., and intrasplenic routes. In the experimental metastasis assay, the lungs of the WT mice were filled with metastatic nodules, whereas the lungs of the fetuin-A null mutant mice were virtually free of colonies at the end of 2 weeks. Lung colonization responded to the levels of serum fetuin-A in a dose-dependent manner, as observed by the formation of half as many colonies in mice heterozygous for the fetuin-A locus compared with homozygous WT mice and restoration of lung colonization by the administration of purified fetuin-A to fetuin-A-null mice. Serum fetuin-A also influenced the growth of LLC cells injected s.c.: fetuin-A-null mice developed small s.c. tumors only after a substantial delay. Similarly, intrasplenic injection of LLC cells resulted in rapid colonization of the liver with metastasis to the lungs within 2 weeks in the WT but not fetuin-A null mice. To examine the mechanism by which fetuin-A influences LLC colonization and growth, we showed that LLC tumor cells adhere to fetuin-A in a Ca2+-dependent fashion, resulting in growth of the tumor cells. These studies support the role of fetuin-A as a major growth promoter in serum that can influence tumor establishment and growth.

The serum glycoprotein fetuin-A promotes Lewis lung carcinoma tumorigenesis via adhesive-dependent and adhesive-independent mechanisms

Fetuin-A is a serum glycoprotein in the cystatin family associated with the regulation of soft tissue calcification. We tested the role of systemic fetuin in tumor cell growth and metastasis by injecting Lewis lung carcinoma (LLC) cells into fetuin-A null and their wild-type (WT) littermate control C57BL/6 mice via the tail vein, s.c., and intrasplenic routes. In the experimental metastasis assay, the lungs of the WT mice were filled with metastatic nodules, whereas the lungs of the fetuin-A null mutant mice were virtually free of colonies at the end of 2 weeks. Lung colonization responded to the levels of serum fetuin-A in a dose-dependent manner, as observed by the formation of half as many colonies in mice heterozygous for the fetuin-A locus compared with homozygous WT mice and restoration of lung colonization by the administration of purified fetuin-A to fetuin-A-null mice. Serum fetuin-A also influenced the growth of LLC cells injected s.c.: fetuin-A-null mice developed small s.c. tumors only after a substantial delay. Similarly, intrasplenic injection of LLC cells resulted in rapid colonization of the liver with metastasis to the lungs within 2 weeks in the WT but not fetuin-A null mice. To examine the mechanism by which fetuin-A influences LLC colonization and growth, we showed that LLC tumor cells adhere to fetuin-A in a Ca(2+)-dependent fashion, resulting in growth of the tumor cells. These studies support the role of fetuin-A as a major growth promoter in serum that can influence tumor establishment and growth.

Matrix metalloproteinases in colorectal cancer: is it worth talking about?

Matrix metalloproteinases (MMPs), a family of extracellular matrix degrading enzymes, are expressed in various stages of colorectal cancer (CRC) and correlate with survival and prognosis. There is considerable evidence in preclinical models that MMP inhibitors (MMPIs) are effective at multiple stages of CRC tumor progression, including reducing the number of intestinal adenomas, inhibiting the growth and establishment of primary CRC tumors, and reducing metastasis to the lung and liver. However, clinical trials with MMPIs in other tumor types have been largely unsuccessful, raising the question as to whether MMPs represent therapeutic targets in CRC. This review focuses on the expression, role, and contribution of MMP family members to various stages of CRC tumor progression. The conclusion is that there is considerable evidence to suggest that MMP inhibition may be an effective strategy if applied at either end of the tumor progression spectrum; the prevention of adenomas, or the treatment of micrometastatic disease.

Radiotherapy in the management of orbital lymphoma

PURPOSE

This retrospective study reviews the treatment technique, disease outcome, and complications of radiotherapy used in the management of lymphoma involving the orbits.

PATIENTS & METHODS

Thirty-eight patients were treated between May 1969 and January 1995, with a median follow-up of 8.3 years. All patients had biopsy-proven orbital lymphoma. Twenty patients who had limited disease were treated with curative intent, and 18 patients who had known systemic disease were treated with palliative intent. Of the 20 patients treated with curative intent, 14 had low-grade and 6 had intermediate- or high-grade disease. None received chemotherapy. Most patients received treatment with 250 kVP or 60Co radiation, using either an en face anterior field or wedged anterior and lateral fields. Median treatment dose was 25 Gy. Lens shielding was performed if possible. For patients treated for cure, cause-specific survival and freedom from distant relapse were calculated using the Kaplan-Meier method.

RESULTS

Control of disease in the orbit was achieved in all but 1 patient, who developed an out-of-field recurrence after irradiation of a lacrimal tumor and was salvaged with further radiotherapy. In the patients treated curatively, the 5-year rate of actuarial freedom from distant relapse was 61% for those with low-grade and 33% for those with intermediate/high-grade disease (p = 0.08). Cause-specific survival at 5 years was 89% for patients with low-grade and 33% for those with intermediate/high-grade disease (p = 0.005). Two patients with low-grade disease had contralateral orbital failures; both were salvaged with further irradiation. Acute toxicity was minimal. Cataracts developed in 7 of 21 patients treated without lens shielding and 0 of 17 patients treated with lens shielding. No patient developed significant late lacrimal toxicity.

CONCLUSION

Radiotherapy is a safe and effective local treatment in the management of orbital lymphoma.