Decrease In Number Of Tumors Research Articles

Kurarinol restrains non-alcoholic fatty liver disease-associated hepatocellular carcinoma (HCC) progression by suppressing EGFR signaling

Non-alcoholic fatty liver disease (NAFLD) is a hepatic manifestation of metabolic syndrome and a key factor for hepatocellular carcinoma (HCC) development. As a metabolic hepatic damage, there is still a lack of efficient therapy for NAFLD-HCC. Kurarinol (KUR) is a flavanone extracted from the root of Sophora flavescens, and exerts excellent hepatoprotective and lipid-lowering activities. But its potential on NAFLD-HCC still remains unclear, and thus was explored in our present study. Firstly, in vitro experiments revealed that KUR treatments markedly reduced lipid deposition and inflammatory response in hepatocytes under palmitate and oleic acid stimulation (PO) with decreased expression levels of fatty acid synthesis markers including fatty acid synthase (FASN), stearoyl-CoA desaturase-1 (SCD1) and sterol receptor element binding protein-1 (SREBP-1). Importantly, the proliferation of HCC cell lines was strongly limited by KUR in a dose-dependent manner. Of note, PO stimulation accelerated the proliferative capacity of HCC cells, whereas being significantly suppressed by KUR. Mechanistically, we found that epidermal growth factor receptor (EGFR) and its phosphorylation protein expression levels were highly down-regulated in hepatocytes and HCC cell lines under PO stimuli. More importantly, the functions of KUR to restrain lipid accumulation and HCC cell proliferation were diminished upon EGFR overexpression, confirming that EGFR suppression was necessary for KUR to treat NAFLD-HCC. Murine mouse models were finally established by the use of diethylnitrosamine (DEN) with high-fat/high-cholesterol diet (HFHC) feeding to determine the role of KUR in NAFLD-HCC. Oral gavage of KUR efficiently suppressed NAFLD-HCC formation in mice, as evidenced by the decreased tumor number and loading. KUR also ameliorated lipid accumulation, liver dysfunction, fibrosis and HCC cell proliferation in DEN/HFHC-challenged mice, along with decreased EGFR expression. Collectively, KUR may be an effective strategy for NAFLD-HCC prevention via EGFR signaling suppression.

Conditional knockout of the NSD2 gene in mouse intestinal epithelial cells inhibits colorectal cancer progression.

Nuclear receptor-binding SET domain 2 (NSD2) is a histone methyltransferase, that catalyzes dimethylation of lysine 36 of histone 3 (H3K36me2) and is associated with active transcription of a series of genes. NSD2 is overexpressed in multiple types of solid human tumors and has been proven to be related to unfavorable prognosis in several types of tumors. We established a mouse model in which the NSD2 gene was conditionally knocked out in intestinal epithelial cells. We used azoxymethane and dextran sodium sulfate to chemically induce murine colorectal cancer. The development of colorectal tumors were investigated using post-necropsy quantification, immunohistochemistry, and enzyme-linked immunosorbent assay (ELISA). Compared with wild-type (WT) control mice, NSD2fl/fl -Vil1-Cre mice exhibited significantly decreased tumor numbers, histopathological changes, and cytokine expression in colorectal tumors. Conditional knockout of NSD2 in intestinal epithelial cells significantly inhibits colorectal cancer progression.

Ochratoxin A promotes chronic enteritis and early colorectal cancer progression by targeting Rinck signaling.

Mycotoxins, such as aflatoxin and ochratoxin A (OTA), are found at measurable levels in many staple foods; the health implications of long-term exposure of such toxins are poorly understood. Increasing evidence has confirmed the important role of OTA in upregulation of oxidative stress- and inflammatory response-induced tissue injury. However, it remains unknown whether ochratoxin A can promote chronic colitis and its associated colon cancer (CRC) development, and potential molecular mechanism. Additionally, RING finger-interacting protein with C kinase (RINCK) is a ubiquitin ligase and mediates immune response. Unfortunately, the potential molecular function of RINCK on regulation of colitis is still largely unknown. This study aims to provide mechanistic evidence that the role of RINCK in colitis and early colorectal cancer progression in response to OTA treatment via targeting nuclear factor erythroid 2-related factor 2 (NRF2). The Cancer Genome Atlas (TCGA) database, GEO database, human subjects with CC phenotype and CC cell lines were used in this work. Pathological links between OTA, RINCK and treatment of CC are revealed through comprehensive means such as biological information analysis, clinical experiments, RNA-seq, and verification experiments. In this study, under oxidative stress in setting of colitis, we first identified RINCK as a key regulatory factor and a novel endogenous suppressor of nuclear factor erythroid 2-related factor 2 (NRF2), and we also confirm that RINCK is a NRF2 partner protein that catalyses its ubiquitination and degradation in intestinal epithelial cells (IECs). Notably, in vivo study, pathological phenotypes triggered by OTA pretreatment, accompanied by post-treatment of dextran sulfate sodium (DSS)-induced colitis was significantly mitigated by IEC-specific deficiency of Rinck, IEC-Rinck(KO) and adenovirus-associated virus (AAV)-triggered suppression of Rinck in rodent model, and lentivirus (LV)-mediated downregulation of Rinck (LV-shRinck) in rabbit model, as determined by decreased endogenous reactive oxygen species (ROS) production, pro-inflammatory cytokines contents, improved body weights, reduced survival rates, restored colon length, assuasive DAI and histological scores. Inversely, transgenic mice by IEC-specific Rinck overexpression, IEC-Rinck(OE) accelerated colitis in acute or chronic colitis rodent models and in vitro experiments. Moreover, we found that OTA pretreatment-promoted azoxymethane (AOM)/DSS-induced colitis-associated early colorectal cancer (CRC) was also dramatically reduced by IEC-Rinck(KO), indicated by the decreased tumor number and corresponding KI-67 levels. Clinical samples analysis revealed that RINCK levels were greatly increased in tumor tissues of patients with CRC phenotypes. In parallel, RINCK deletion remarkably retarded the proliferation of colon cancer and tumor growth in vitro and in vivo, respectively. Mechanistically, in response to onset of colitis, RINCK directly interacts with NRF2 and promotes ubiquitin-proteasome degradation via increasing K48-linkage ubiquitin chain, thus leads in suppression of NRF2 nuclear translocation and its downstream cascade inactivation, which retards antioxidant defense. The findings suggested that oral sub-chronic exposure of OTA significantly facilitates DSS-induced colitis and colitis-associated CRC development. These results further elucidated the potential role of RINCK in colitis progression by mediating NRF2 degradation, and could be considered as a therapeutic target for the treatment of such disease.

Abstract 5176: CDDO-methyl ester redirects macrophage polarization and reduces lung tumor burden in a Nrf2-dependent manner

Abstract The cytoprotective Nrf2 pathway impacts immune cell function and has been proposed as a target for many inflammation-related diseases, but the effects of Nrf2 activation on immune cells in the cancer context are not well characterized. With Nrf2 activators under development and in clinical trials, it is critical to understand the influence of these drugs on cancer progression. While the anti-inflammatory nature of Nrf2 activation protects healthy cells from malignant transformation, cancer cells can utilize the pathway to promote resistance to anti-cancer drugs and increase tumor cell survival. Up to 30% of human lung adenocarcinomas acquire mutations in the Nrf2 pathway which result in constitutive activation. However, triterpenoids, including CDDO-methyl ester (CDDO-Me, also known as bardoxolone methyl), are potent pharmacological Nrf2 activators with demonstrated anti-cancer activity in preclinical models. Lung cancer is the leading cause of cancer-related mortality worldwide, and macrophages are the most common immune cell type in the lung tumor microenvironment. To investigate Nrf2 activation in macrophages in the context of lung cancer, bone marrow-derived macrophages (BMDMs) were isolated from wild type (WT) and Nrf2 knock out (KO) mice and cultured in conditioned media from lung cancer cells to produce a tumor-educated phenotype. The triterpenoid CDDO-Me had anti-inflammatory effects in BMDMs stimulated with the conventional cytokines IFN-γ and LPS. Conversely, CDDO-Me increased (p < 0.05) the M1 macrophage markers TNFα, IL-6, and MHC-II and decreased the M2 macrophage markers VEGF, CCL2, and CD206 in tumor-educated BMDMs in a Nrf2-dependent manner. The phenotypic changes were observed on transcription, protein, and surface marker levels. This context-dependent reversal of BMDM polarization suggests that Nrf2 activation has different outcomes in different environments. To test CDDO-Me in vivo, lung tumors were initiated with vinyl carbamate in A/J WT and Nrf2 KO mice, and animals were fed either control diet or CDDO-Me (12.5-50 mg/kg of diet) for 16 weeks. CDDO-Me significantly (p < 0.05) decreased tumor number, size, and overall burden and reduced the histopathological severity of tumors in a Nrf2- and dose-dependent manner. Additionally, CDDO-Me increased the infiltration of CD64+ macrophages but decreased CD206+ expression in macrophages in the lungs of WT tumor-bearing mice. Interestingly, CD206 expression was higher on macrophages in the spleen of WT mice treated with CDDO-Me, suggesting a cancer context dependency. Future studies will evaluate the dependency of Nrf2 activation in macrophages for the anti-tumor activity of CDDO-Me. Citation Format: Jess Ann Moerland, Karen T. Liby. CDDO-methyl ester redirects macrophage polarization and reduces lung tumor burden in a Nrf2-dependent manner. [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 5176.

The Appendix Orchestrates T-Cell Mediated Immunosurveillance in Colitis-Associated Cancer

Although appendectomy may reduce colorectal inflammation in patients with ulcerative colitis (UC), this surgical procedure has been suggested to be associated with an increased risk of colitis-associated cancer (CAC). Our aim was to explore the mechanism underlying the appendectomy-associated increased risk of CAC. Five-week-old male BALB/c mice underwent appendectomy, appendicitis induction, or sham laparotomy. They were then exposed to azoxymethane/dextran sodium sulfate (AOM/DSS) to induce CAC. Mice were killed 12 weeks later, and colons were taken for pathological analysis and immunohistochemistry (CD3 and CD8 staining). Human colonic tumors from 21 patients with UC who underwent surgical resection for CAC were immunophenotyped and stratified according to appendectomy status. Whereas appendectomy significantly reduced colitis severity and increased CAC number, appendicitis induction without appendectomy led to opposite results. Intratumor CD3+ and CD8+ T-cell densities were lower after appendectomy and higher after appendicitis induction compared with the sham laparotomy group. Blocking lymphocyte trafficking to the colon with the anti-α4β7 integrin antibody or a sphingosine-1-phosphate receptor agonist suppressed the inducing effect of the appendectomy on tumors' number and on CD3+/CD8+ intratumoral density. CD8+ or CD3+ T cells isolated from inflammatory neo-appendix and intravenously injected into AOM/DSS-treated recipient mice increased CD3+/CD8+ T-cell tumor infiltration and decreased tumor number. In UC patients with a history of appendectomy, intratumor CD3+ and CD8+ T-cell densities were decreased compared with UC patients without history of appendectomy. In UC, appendectomy could suppress a major site of T-cell priming, resulting in a less efficient CAC immunosurveillance.

Intestinal epithelial cell autophagy deficiency suppresses inflammation-associated colon tumorigenesis

Colitis-associated cancer (CAC) is closely related to chronic inflammation, whose underlying molecular mechanism, however, has not been elaborated comprehensively. In the current study, an investigation was conducted on the role of autophagy in the initiation and progression of azoxymethane (AOM)/dextran sulfate sodium (DSS)-induced colon tumors, a mouse model for CAC in humans. Mice with the intestinal epithelial cell (IEC)-specific deletion of the autophagy-related gene 7 (Atg7) saw a significant decrease in tumor number, burden, and risk of high-grade dysplasia. The autophagy deficiency of IECs resulted in the accumulation of T cells, especially CD8+ T lymphocytes in colon lamina propria. Furthermore, it was found that autophagy protects against DSS-induced intestinal injury through maintaining epithelial barrier function and promoting the survival and proliferation of IECs. Mechanistically, autophagy in IECs enhanced the activation of epithelial STAT3/ERK to promote the survival and proliferation of colonic epithelial cells during the development of CAC. Therefore, the findings unveil the essential role of autophagy in activating the processes of colonic protection, regeneration, and tumorigenesis.

Determination of in vivo virtue of dermal targeted combinatorial lipid nanocolloidal based formulation of 5-fluorouracil and resveratrol against skin cancer

The current study has been designed to appraise the efficacy of developed combinatorial lipid-nanosystem-based gel (linogel) of 5-fluorouracil and resveratrol for skin cancer treatment. Initially, linogel was prepared and characterized for different parameters, namely pH, texture, drug content uniformity, occlusiveness, etc. Then in vivo efficacy studies (tumor number, area, and volume, histopathology, ultrastructural and immunohistochemical analysis) of linogel were determined over-developed skin tumors. Developed linogel possessed significantly (p < 0.05) better texture and occlusiveness than conventional gel formulation. Decreased tumor number, area, and volume showed significant results (p < 0.05) in favor of linogel. Histopathological and ultrastructural analysis confirmed superior efficacy of linogel in terms of marked improvement in the nucleus and subcellular structures in photomicrographs. The antioxidants and anti-inflammatory analysis findings showed a significantly (p < 0.05) potent effectiveness of linogel. The apoptotic and anti-proliferation activity of linogel was confirmed by analysis of caspase-3 and ki-67, which showed significant (p < 0.05) elevation in the level of cleaved caspase-3 and reduction in the level of ki-67 than untreated and conventional gel formulation treated tumors, indicating antitumor effect due to cancerous cell death. Thus, developed linogel fulfilled all the criteria of dermal application and exhibited efficacious therapeutic results, which could be a beneficial therapeutic approach against skin cancer.

MicroRNA-155 contributes to plexiform neurofibroma growth downstream of MEK.

MicroRNAs (miRs) are small non-coding RNAs that can have large impacts on oncogenic pathways. Possible functions of dysregulated miRs have not been studied in neurofibromatosis type 1 (NF1) plexiform neurofibromas (PNFs). In PNFs, Schwann cells (SCs) have biallelic NF1 mutations necessary for tumorigenesis. We analyzed a miR-microarray comparing to normal and PNF SCs and identified differences in miR expression, and we validated in mouse PNFs versus normal mouse SCs by qRT-PCR. Among these, miR-155 was a top overexpressed miR, and its expression was regulated by RAS/MAPK signaling. Overexpression of miR-155 increased mature Nf1−/− mouse SC proliferation. In SC precursors, which model tumor initiating cells, pharmacological and genetic inhibition of miR-155 decreased PNF-derived sphere numbers in vitro and we identified Maf as a miR-155 target. In vivo, global deletion of miR-155 significantly decreased tumor number and volume, increasing mouse survival. Fluorescent nanoparticles entered PNFs, suggesting that an anti-miR might have therapeutic potential. However, treatment of established PNFs using anti-miR-155 peptide nucleic acid-loaded nanoparticles marginally decreased tumor numbers and did not reduce tumor growth. These results suggest that miR-155 plays a functional role in PNF growth and/or SC proliferation, and that targeting neurofibroma miRs is feasible, and might provide novel therapeutic opportunities.

Abstract 1624: Lrig1 is an Egfr-dependent tumor suppressor in mouse duodenal and colonic neoplasia

Abstract Leucine-rich repeats and immunoglobulin-like domain 1 (Lrig1) is a pan-ErbB negative regulator. Lrig1 null mice develop spontaneous duodenal adenomas by 3-4 months of age but they exhibit no overt colonic pathology (AE Powell Cell 149:146-158, 2012). To examine a possible tumor suppressor role for Lrig1 in colonic neoplasia, we utilized Lrig1CreERT2 and Lrig1Apple mice in which a tamoxifen-inducible Cre recombinase or an Apple fluorescent reporter were inserted into the translational start site of endogenous Lrig1, thus creating Lrig1 null mice. Colonic tumors were generated by administration of AOM/DSS to Lrig1CreERT2/CreERT2 mice and by administration of tamoxifen (TAM) to Lrig1CreERT2/Apple;Apcflox/+ mice to induce loss of one Apc allele. Compared to littermate control mice, there was a significant increase in colonic tumor number in both Lrig1 null cohorts (p=0.016 and p=0.007, respectively). We previously reported Egfr was the most upregulated ErbB family member in Lrig1 null duodenal tumors (Y Wang Am J Path 185:1123-1134, 2015). To directly implicate Egfr in both Lrig1 null duodenal and colonic tumors, we administered TAM at 6 weeks of age to Lrig1CreERT2/CreERT2;Egfrflox/flox mice. At 6 months of age, all oil-injected mice developed tumors, whereas tumors were not detected in 8/21 (38.1%) of TAM-injected mice; the tumor volume in TAM-injected mice was reduced to 7.78 mm3 (73.5%) compared to (10.58 mm3) in the oil-injected group as measured by MRI scanning (p&amp;lt;0.05). In the AOM/DSS colonic tumor model, administration of TAM at 6 weeks of age to Lrig1CreERT2/CreERT2;Egfrflox/flox mice resulted in a significant decrease in tumor number (p=0.021) but not size compared to oil-injected mice. These results indicate that Lrig1 is an Egfr-dependent tumor suppressor in both mouse duodenal and colonic neoplasia. Citation Format: Robert J. Coffey, Hiro Niitsu, Yuanyuan Lu, Won Jae Huh, Jeffrey L. Franklin. Lrig1 is an Egfr-dependent tumor suppressor in mouse duodenal and colonic neoplasia [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 1624.

Abstract 5357: Total abdominal ultra-rapid FLASH irradiation enhances the efficacy of PD-1 inhibition in preclinical models of ovarian cancer

Abstract Objective: Ovarian cancer often presents with advanced stage disease. Despite surgery and chemotherapy, recurrence remains inevitable and prognosis poor. Advances in immunotherapy including programmed cell death-1 (PD-1) inhibition show promise, however clinical trials show modest response rates as a single agent therapy in ovarian cancer patients. Radiation therapy is an attractive strategy to enhance the efficacy of immune checkpoint blockade in ovarian cancer due to its ability to increase tumor-infiltrating lymphocytes and enhance immune activation. While ovarian cancer is known to be radiosensitive, total abdominal radiation is not routinely utilized due to high abdominopelvic toxicity. We have recently shown that ultra-high dose rate FLASH irradiation reduces intestinal radiation-induced toxicity. Importantly, we demonstrated efficient tumor control in preclinical models of ovarian cancer peritoneal metastasis. Here we sought to determine the efficacy and safety of FLASH irradiation combined with PD-1 inhibition in preclinical models of ovarian cancer. Methods: Female C57BL/6 mice were intraperitoneally inoculated with ID8-Asc or UPK10 ovarian cancer cells. Total abdominal FLASH irradiation at 14 Gy was administered 10 days post-inoculation. Anti-PD-1 and isotype control antibodies were injected on days 7, 10, and 13 post-inoculation. Mice were sacrificed 22-27 days post-inoculation for tumor burden and immune cell analysis. Stool count, stool weight, complete blood count, and survival were evaluated to compare acute and chronic toxicity as well as efficacy in the treatment arms. Results: Four cohorts of mice were analyzed: Isotype control antibody (IgG), anti-PD-1 (aPD-1), FLASH + IgG, and FLASH + aPD-1. In the ID8-Asc model, irradiated mice showed a 44% decrease in solid stool production with subsequent recovery to baseline by 14 days post-treatment. There was no evidence of hematopoietic toxicity in any of the treatment arms. Survival analysis is ongoing. Exploratory necropsy demonstrated significant tumor burden control in the FLASH cohorts, and in particular, a 25-fold decrease in tumor number in the FLASH + aPD-1 cohort compared to control (mean tumor weight 1.82 mg vs. 357.2 mg, respectively). FLASH + aPD-1 increased intratumoral CD4+ and CD8+ T cells and correlated with enhanced tumor control compared to FLASH or aPD-1 single agent treatments. Similar results were observed in the UPK10 model. Conclusion: Combination FLASH and PD-1 inhibition enhanced tumor control and recruitment of tumor infiltrating lymphocytes compared to IgG, aPD-1, and FLASH treatments alone, while demonstrating safety and tolerability. Our data identify a new opportunity for FLASH and checkpoint inhibition in the treatment of ovarian cancer. Citation Format: Stephanie Chow, Joshua T. Eggold, Karen Levy, Jinghui Wang, Rakesh Manjappa, Dylan Y. Breitkreutz, Amy S. Yu, Karl Bush, Oliver Dorigo, Billy W. Loo, Erinn B. Rankin. Total abdominal ultra-rapid FLASH irradiation enhances the efficacy of PD-1 inhibition in preclinical models of ovarian cancer [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 5357.

Blocking NFATc3 ameliorates azoxymethane/dextran sulfate sodium induced colitis-associated colorectal cancer in mice via the inhibition of inflammatory responses and epithelial-mesenchymal transition

Ulcerative colitis-associated colorectal cancer (UC-CRC) is the most serious complication of ulcerative colitis (UC). Nuclear factor of activated T cells 3 (NFATc3) is participated in inflammation and cancer. In this study, we investigated the effects of NFATc3 on experimental UC-CRC in vivo and in vitro, and explored the underlying mechanisms. Administration of azoxymethane (AOM) and dextran sulfate sodium (DSS) induced UC-CRC model in C57BL/6 mice. Body weight was monitored weekly. Colon tissues were harvested at week 14. We examined changes in the histopathology, inflammatory cytokines, carcinogenesis factors, and epithelial-mesenchymal transition (EMT) markers in colon tissues. We found that NFATc3 expression was significantly up-regulated in AOM/DSS treated mice compared with control. Mice lacking NFATc3 showed decreased tumor number and size, decreased mucosal damage, and increased survival rate. Moreover, down-regulation of NFATc3 could inhibit the proliferation and EMT of UC-CRC, decrease the levels of pro-inflammatory cytokines, reduce the colonic infiltration by neutrophils and macrophages, and suppress the activation of P38 and JNK signal pathway in mice. In In vitro experiments, silencing NFATc3 suppressed the proliferation and EMT of CRC cells, and reduced the activation of P38 and JNK. In addition, miR-370-3p could bind to NFATc3. Down-regulation of miR-370-3p promoted proliferation and EMT of CRC cells, while silencing NFATc3 could reverse these effects. In conclusion, NFATc3 was involved in the pathogenesis of experimental UC-CRC and NFATc3 knockdown ameliorated experimental UC-CRC progression via the inhibition of inflammatory responses and EMT. NFATc3 mediated the inhibitory effects of miR-370-3p on CRC cells proliferation and EMT. Targeting NFATc3 may be effective in treating UC-CRC.

The germ-free mice monocolonization with Bacteroides fragilis improves azoxymethane/dextran sulfate sodium induced colitis-associated colorectal cancer

Objective: Inflammatory bowel disease (IBD) is generally considered as a major risk factor in the progression of colitis-associated colorectal cancer (CAC). Previous studies have indicated that the composition of gut microflora may be involved in CAC induction and progress. Bacteroides fragilis (BF) is a Gram-negative anaerobe belonging to colonic symbiotic bacteria of the host. This study was aimed to investigate the protective role of BF in a colorectal cancer (CRC) model induced by azoxymethane (AOM) and dextran sulfate sodium (DSS) in germ-free (GF) mice.Materials and methods: Total 22 GF mice were divided into two groups: GF and BF group. Half of the GF mice were colonized with BF for 28 days before CRC induction by AOM/DSS.Results: BF colonization increased animal survival (100%). Cecum weight and cecum/body weight ratio significantly decreased in BF/AOM/DSS group. Interestingly, there was a significant decrease in tumor number and tumor incidence in the BF/AOM/DSS group as compared to the GF/AOM/DSS group. The adenocarcinoma/adenoma incidence and histologic score were also decreased in the BF/AOM/DSS group. In addition, immunohistochemistry staining found decreased numbers of cell proliferation (PCNA) and inflammatory cell (granulocytes) infiltration in the colon mucosa of the BF group. The β-catenin staining in the BF/AOM/DSS group had fewer and weaker positive signal expressions. Taking together, the BF colonization significantly ameliorated AOM/DSS-induced CRC by suppressing the activity of cell proliferation-related molecules and reducing the number of inflammatory cells.Conclusions: Symbiotic BF may play a pivotal role in maintaining the gastrointestinal immunophysiologic balance and regulating anti-tumorigenesis responses.

A new drug combination significantly reduces kidney tumor progression in kidney mouse model.

Tuberous sclerosis complex (TSC) disease is associated with tumors in many organs, particularly angiomyolipoma (AML) in the kidneys. Loss or inactivation of TSC1/2 results in high levels of HIF-α activity and VEGF expression. mTOR inhibitor (rapamycin) and the AMPK activator 5-aminoimidazole-4-carboxamide (AICA)-riboside (AICAR) are currently used separately to treat cancer patients. Here, we investigated the effect of a novel combination of rapamycin and AICAR on tumor progression. Our data show that treatment of AML human cells with drug combinations resulted in 5-7-fold increase in cell apoptosis compared to each drug alone. In addition, drug combinations resulted in 4-5-fold decrease in cell proliferation compared to each drug alone. We found that drug combinations abolished Akt and HIF activity in AML cells. The drug combinations resulted in decrease in cell invasion and cell immigration by 70% and 84%, respectively in AML cells. The combined drugs also significantly decreased the VEGF expression compare to each drug alone in AML cells. Drug combinations effectively abolished binding of HIF-2α to the putative Akt site in the nuclear extracts isolated from AML cells. Treatment TSC mice with drug combinations resulted in 75% decrease in tumor number and 88% decrease in tumor volume compared to control TSC mice. This is first evidence that drug combinations are effective in reducing size and number of kidney tumors without any toxic effect on kidney. These data will provide evidence for initiating a new clinical trial for treatment of TSC patients.

Macrophage depletion using clodronate liposomes decreases tumorigenesis and alters gut microbiota in the AOM/DSS mouse model of colon cancer.

We examined the role of macrophages in inflammation associated with colorectal cancer (CRC). Given the emerging evidence on immune-microbiota interactions in CRC, we also sought to examine the interaction between macrophages and gut microbiota. To induce CRC, male C57BL/6 mice ( n = 32) received a single injection of azoxymethane (AOM), followed by three cycles of dextran sodium sulfate (DSS)-supplemented water in weeks 1, 4, and 7. Prior to the final DSS cycle ( week 7) and twice weekly until euthanasia, mice ( n = 16/group) received either 200 μl ip of clodronate-filled liposomes (CLD) or phosphate-buffered saline (PBS) encapsulated liposomes to deplete macrophages. Colon tissue was analyzed for polyp burden, macrophage markers, transcription factors, and inflammatory mediators. Stool samples were collected, and DNA was isolated and subsequently sequenced for 16S rRNA. Clodronate liposomes decreased tumor number by ∼36% and specifically large (≥1 mm) tumors by ∼36% ( P < 0.05). This was consistent with a decrease in gene expression of EMR1 in the colon tissue and polyp tissue as well as expression of select markers associated with M1 (IL-6) and M2 macrophages (IL-13, IL-10, TGFβ, CCL17) in the colon tissue ( P < 0.05). Similarly, there was a decrease in STAT3 and p38 MAPK and ERK signaling in colon tissue. Clodronate liposomes increased the relative abundance of the Firmicutes phylum ( P < 0.05) and specifically Lactobacillaceae and Clostridiaceae families, which have been associated with reduced CRC risk. Overall, these data support the development of therapeutic strategies to target macrophages in CRC and provide support for further evaluation of immune-microbiota interactions in CRC. NEW & NOTEWORTHY We found that macrophage depletion during late-stage tumorigenesis is effective at reducing tumor growth. This was associated with a decrease in macrophage markers and chemokines in the colon tissue and a decrease in transcription factors that are linked to colorectal cancer. The macrophage-depleted group was found to have an increased abundance of Firmicutes, a phylum with documented anti-tumorigenic effects. Overall, these data support the development of therapeutic strategies to target macrophages in colorectal cancer.

Abstract 3714: Muc5ac plays an essential role in promotion of k-ras mutant lung cancer

Abstract Worldwide, lung cancer is the leading cause of cancer mortality, and cigarette smoking (CS) is its principal cause. However, several studies have found that smokers with chronic obstructive pulmonary disease (COPD), an inflammatory disease of the lung, have an increased risk of lung cancer (3 to 10-fold) compared to smokers with comparable cigarette exposure but without COPD. Importantly, among smokers with COPD, even following withdrawal of cigarette smoke, inflammation persists and lung function continues to deteriorate as does the increased risk of lung cancer. These facts suggest a strong link between COPD-related lung inflammation and lung cancer, however, the precise mechanistic link is not known. Mucociliary dysfunction and mucin hyperproduction are important features of COPD with inflammation being the major trigger. Interestingly, lung cancer with mucin overexpression has higher malignancy potential and poor prognosis, which around 76% having mutations in K-ras oncogene, the most frequent oncogenic mutation in lung adenocarcinoma. Taken these together, we hypothesized that mucins contribute to promotion of K-ras mutant lung cancer by inflammation. Here we first investigated whether Muc5ac, predominant airway mucin that plays a primary role in inflammatory lung diseases, is predictive of clinical outcome in KRAS-mutant human lung adenocarcinomas. We determined Muc5ac mRNA expression by array analysis of 150 lung adenocarcinomas from patients that did not received neoadjuvant therapy and we found that, Muc5ac mRNA level was a significant predictor of poor disease-free survival in KRAS-mutant lung adenocarcinomas. We have further found increased mucin and high expression of Muc5ac in lung tumor tissues of the mice with airway specific expression of a mutant form of K-ras (CC-LR mice). Then, we crossed previously developed Muc5ac knockout (KO) mice to CC-LR mice in order to develop a K-ras mutant lung cancer mouse model with lack of Muc5ac (CC-LR/Muc5ac KO mice). This resulted in a significant tumor reduction by ~54% (2.2-fold) in lung of CC-LR/Muc5ac KO mice compared to age and sex matched control CC-LR mice. Lung inflammation was evaluated by analysis of bronchoalveolar lavage fluid and revealed a significant reduction (3-fold) in number of macrophages, and levels of IL-6 and IL-17 in CC-LR/Muc5ac KO mice compared to CC-LR control mice. Immunohistopathological analysis of lung sections confirmed lower inflammation, decreased tumor number and size, less adenomatous lesions, and reduced tumor cell proliferation and angiogenesis in CC-LR mice with lack of Muc5ac compared to control CC-LR mice. Our experimental results suggest that Muc5ac has an essential role in promotion of K-ras mutant lung cancer through autocrine cell intrinsic and paracrine immune cell mediated mechanisms. Citation Format: Misha Umer, Amber M. Cumpian, Nasim Khosravi, Zoulikha Azzegagh, Maede Mohebnasab, Mauricio S. Caetano, Edwin J. Ostrin, Ignacio I. Wistuba, Burton Dickey, Humam Kadara, Christopher M. Evans, Seyed J. Moghaddam. Muc5ac plays an essential role in promotion of k-ras mutant lung cancer [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 3714. doi:10.1158/1538-7445.AM2017-3714

Macrophage depletion decreases tumorigenesis and alters gut microbiota in the AOM/DSS mouse model of colon cancer

Abstract Macrophages are recognized as major players in the connection between inflammation and cancer; they represent up to 50% of the tumor mass and produce a wide array of inflammatory mediators with pro-tumoral functions. Emerging evidence links gut microbiota to the development of colorectal cancer and host-derived immune and inflammatory responses are important driving forces that can shape microbial community composition. We used a macrophage depletion technique to examine the role of macrophages on colon tumorigenesis and gut microbiota. To induce colorectal cancer, male C57BL/6 mice (n=32) received a single injection of AOM followed by three cycles of DSS supplemented water at concentrations of 2%, 1%, 1% at weeks 1, 4, and 7, respectively. Prior to the final DSS cycle (week 7) and twice weekly until sacrifice, mice (n=16/group) received 200ul i.p. of clodronate (CL2MDP) or PBS encapsulated liposomes to deplete macrophages. Mice were sacrificed at 12 weeks following the initial AOM injection and colon tissue was analyzed for tumor burden, macrophage markers, and inflammatory mediators. Stool samples were collected and DNA was isolated and subsequently sequenced for 16S rRNA. Macrophage depletion decreased tumor number by ~35% and specifically large (≥1mm) tumors by ~35% (p&amp;lt;0.05). This was consistent with a decrease in gene expression of EMR1 (overall macrophage marker) as well as expression of markers associated with M2 macrophages (IL-13, IL-10, TGFβ &amp; CCL17) (p&amp;lt;0.05) but not M1 markers (NOS2, IL-12a &amp; IL-23). Macrophage depletion also increased relative abundance of the Firmicutes phylum (p&amp;lt;0.05) in stool. We demonstrate that macrophages are important mediators of tumor growth and changes in gut microbiota in colorectal cancer.

Abstract B017: Bacterial minicells decrease tumor development and modulate immunity in a mouse mouse model of colon cancer

Abstract Background: Colorectal cancer is the second leading cause of cancer deaths in the US. Genetic predisposition occurs in ∼30% of cases, suggesting that treatments with the ability to decrease lesion formation could significantly improve disease-free survival in potential patients with a strong family history. Genetically-engineered bacterial minicells (MC) are noninfectious, nano-sized bacterial particles derived from E. coli that can display immunomodulatory and antitumor activity in animal models of cancer. The expression of Invasin on the MC surface targets them to cancer-associated integrin heterodimers exposed on malignant cells, where they deliver Perfringolysin O, a unique tumorlytic bacterial toxin, that destroys these cells. We hypothesize that these MC can reduce colon lesions in genetically predisposed animals and that they have potential to be developed as a ‘probiotic’ therapy for individuals at high risk to develop colorectal cancer. Methods: The TS4CRE mouse line expresses the Cre recombinase specifically in the distal ileum and colon under the control of the fatty acid binding protein-4 promoter. The Apcfl-468 mouse line has lox-P recombination sites flanking exons 11-12 of the Apc gene. Cross-breeding results in a deletion in one allele of the Apc gene in a tissue-specific manner, resulting in lesion formation by 14-18 weeks of age. Cross-bred mice were treated intra-rectally with 1.5×109 MC or PBS, once a week for 6 doses, at either 8-13 or 14-19 weeks of age and harvested at various times after treatment is complete to evaluate tumor number and size. Tumor and tumor adjacent tissue is evaluated for immune biomarkers using qPCR and immunohistochemistry studies. Mann-Whitney (two-tailed) tests are used to determine statistical significance. Results: MC treatment during lesion development (14-19 weeks of age) significantly decreases tumor number (p = 0.007) and size (p = 0.03) in mice harvested at 6 months of age as compared to controls. Similarly, in animals treated from 8-13 weeks of age, when lesions are absent or only in the earliest stages, a significant decrease in tumor number (p = 0.04) was observed. MC can reduce tumor load through direct killing of developing lesions but they also have the potential to modulate immune responses. Since immune/inflammatory mediators are known to significantly contribute to tumor progression in colorectal cancer, decreased tumors in MC treated mice could be the result, at least in part, of a change in the immune/inflammatory environment of the colon. Chloracetate Esterase (CAE) staining for inflammatory granulocytes and mast cells showed that numbers of CAE+ cells in tumors and normal adjacent tissue from MC treated mice (at 14-19 weeks of age) were significantly lower than PBS-treated controls (p = 0.02). Moreover we saw that cells expressing CD11b, a biomarker for inflammatory, myeloid-lineage cells, were also significantly decreased in MC treated mice (p = 0.01). In addition, using qPCR we have determined that both the CD8 and IFNγ biomarkers were significantly increased in the tumor tissue of MC treated mice (p = 0.03 for each) while perforin and Tbet were increased in the tumor-adjacent tissue in these same mice (p = 0.04 for each), when compared to controls. Conclusions: Taken together, these data strongly suggest that MC reduce colon tumor burden in genetically predisposed mice, most likely both by directly eliminating tumor cells and changing the immune environment of the lesions. The immunomodulatory effects appear to consist of both increased anti-tumor immunity and decreased inflammatory cell infiltration. Future studies will continue to access the actions of these MC and the possibility that they can be developed as a ‘probiotic’ therapeutic approach against colorectal cancer in genetically predisposed individuals. Citation Format: Mengxi Tian, Mohammad W. Khan, Shea Grenier, Shingo Tsuji, Matthew A. Giacalone, Kathleen L. McGuire. Bacterial minicells decrease tumor development and modulate immunity in a mouse mouse model of colon cancer [abstract]. In: Proceedings of the Second CRI-CIMT-EATI-AACR International Cancer Immunotherapy Conference: Translating Science into Survival; 2016 Sept 25-28; New York, NY. Philadelphia (PA): AACR; Cancer Immunol Res 2016;4(11 Suppl):Abstract nr B017.

Abstract LB-272: Histidine decarboxylase (Hdc)-expressing myeloid cells support Foxp3+ Treg cells and promote colorectal cancer progression

Abstract The tumor microenvironment contains a diverse population of myeloid cells that are recruited from bone marrow and converted to immunosuppressive cells, thus mediating tumor cell escape from immune checkpoint. We have identified a subset of dynamic bone marrow myeloid cells, which can be identified by histidine decarboxylase (Hdc) mRNA and GFP expression in Hdc-GFP transgenic mice. Gene expression profiling showed that Hdc-GFP+ CD11b+Gr1+ myeloid cells express higher levels of cell cycle promoting genes such as Ccnd2, Ccnd3 and Cdc14a, while cell proliferation repressors including Cdc14b, Cdc16 and Cdk4 were downregulated in Hdc-GFP+ myeloid cells. To further elucidate the role of Hdc+ myeloid cells in tumor progression, we performed lineage-tracing studies using Hdc-creERT2;R26-LSL-TdTomato reporter mice. Pulsed with tamoxifen, the majority of TdTomato+ cells were localized initially to a group of CD11b+Gr1+ myeloid cells representing the highest Hdc mRNA expression in bone marrow, spleen and blood. Later on, TdTomato+CD11b+Gr1- F4/80+ macrophages can be detected, indicating a hierarchy of Hdc+ myeloid cells in which Hdc+CD11b+Gr1+ myeloid cells reside at the apex. In general, CD11b+ myeloid cells have a relative short lifespan (&amp;lt;2 weeks); however, treatment with dextran sodium sulfate (DSS) in the drinking water increased the longevity and frequency of Hdc+ myeloid cells, also promoted the differentiation of Gr1+ immature myeloid cells into neutrophils and macrophages. In a mouse model of azoxymethane (AOM)/DSS colorectal carcinogenesis, Hdc-creERT2;R26-LSL-TdTomato;R26-LSL-DTA mice were injected with 10 mg/kg AOM and followed by 3 circles of 10 days 1.5% DSS ad libitum in drinking water. We found that Hdc-TdTomato labeled a proportion of tumor infiltrating CD11b+Gr1+ myeloid cells that expressed higher levels of Arg-1, Cox2, and Pdl1 transcripts. Continuous depletion of Hdc+ myeloid cells by administration of tamoxifen chow to induce DTA (diphtheria toxin subunit A) killing in Hdc-expressing myeloid cells abrogated half of the tumor-infiltrating MDSCs and released tumoricidal CD8+ T cells (&amp;gt; 15-fold), leading to decreased tumor number. This tumor suppression could be rescued by Hdc+ CD11b+Gr1+ cell adoptive transfer. Serum chemokine profiling revealed that Hdc+ DTA mediated myeloid depletion also decreased serum chemokine levels, among which Cxcl13 decreased the most (&amp;gt;30-fold). Cxcl13 protein and Cxcl13 mRNA also decreased in the colonic tumor tissue in the Hdc+ myeloid cell depleted AOM/DSS treatment group. Along with reduction in Cxcl13 levels, we also detected a significant reduction of Foxp3+ Treg cells in the tumor frozen sections stained with antibody against Foxp3 compared to R26-LSL-TdTomato;R26-LSL-DTA controls received the same treatments. Pre-knockdown of Cxcl13 by Dicer-substrate SiRNA (DsiRNAs) in a co-culture of splenic Hdc+ CD11b+Gr1+ myeloid cells from colon tumor-bearing mice with splenic Foxp3-GFP+ Treg cells induced apoptosis and decreased numbers of GFP+ cells compared to the scramble knockdown control group. Taken together, our data suggest that Hdc marks a distinct subset of myeloid cells with greater potency for promoting tumorigenicity, in part through supporting Tregs and suppressing CD8+ Tcells in the tumor microenvironment. Citation Format: Xiaowei Chen, Yoshihiro Takemoto, Karan K. Nagar, Timothy H. Chu, Zhengyu Jiang, Wenju Chang, Richard A. Friedman, Yagnesh H. Tailor, Daniel L. Worthley, Timothy C. Wang. Histidine decarboxylase (Hdc)-expressing myeloid cells support Foxp3+ Treg cells and promote colorectal cancer progression. [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 LB-272.

Cyclosporine A immunosuppression drives catastrophic squamous cell carcinoma through IL-22.

Immune-suppressed organ transplant recipients (OTRs) can develop catastrophic squamous cell carcinoma (SCC), characterized by multiple primary tumors, extensive body surface area involvement, or metastases. There are currently no curative systemic therapies available. We previously showed that IL-22 enhances SCC proliferation. Herein, we examined links between cyclosporine (CSA), IL-22, and SCC in patients, cell lines, and mice with UV light-induced SCC. Eighteen of 114 OTRs developed catastrophic SCC, which was strongly associated with CSA treatment. We found that CSA drives T cell polarization toward IL-22-producing T22 cells, and CSA treatment increased IL-22 receptor in SCC cells. SCC tissue from OTRs showed increased expression of IL-22RA1. CSA potentiated rescue by IL-22 of serum-starved SCC cells; treatment of SCC cells with IL-22 and CSA increased both their migratory and invasive capacity. In a UV-induced model of SCC in SKH-1 immunocompetent mice, treatment with anti-IL-22 antibody reduced tumor number and tumor burden. We found that catastrophic SCC in OTRs is associated with CSA use, which may be acting by favoring T22 polarization. Since anti-IL-22 antibody administration decreased tumor number and tumor burden in vivo, blockade of the IL-22 axis may be developed as a viable therapeutic option for catastrophic SCC.

Suppression of intestinal tumors by targeting the mitotic spindle of intestinal stem cells.

Human colorectal cancer is often initiated by the aberrant activation of Wnt signaling, notably following adenomatous polyposis coli (Apc) inactivation. Recent studies identified adult intestinal stem cells (ISCs) and demonstrated their role as the cells of origin for intestinal tumors. However, the early consequences of aberrant Wnt signaling activation remain to be fully elucidated. Here, using organoid cultures established from conditional knockout mice and in vitro gene ablation, we show that Apc inactivation led to aberrant ISC proliferation and the expansion of the crypt domain. This system was used to evaluate the potential of a cancer-related spindle protein, Tacc3, as a target of cancer therapy, as its disruption led to the suppression of tumor formation in an animal model of intestinal tumors. We found that Tacc3 is required for the proper mitosis of Apc-deficient ISCs, and its disruption significantly attenuated the expansion of the crypt domain. In vivo analysis of corresponding mutant mice demonstrated that Tacc3 disruption led to a significant decrease in tumor number and prolonged survival. These observations demonstrated that Tacc3 is a potential chemotherapeutic target for intestinal tumors by perturbing the aberrant cell proliferation of Apc-deficient ISCs and provides an opportunity for the development of novel cancer prevention and treatment.