Modulation Of Tumorigenesis Research Articles

Diabetes Driven Oncogenesis and Anticancer Potential of Repurposed Antidiabetic Drug: A Systemic Review.

Diabetes and cancer are two prevalent disorders, pose significant public health challenges and contribute substantially to global mortality rates, with solely 10 million reported cancer-related deaths in 2020. This review explores the pathological association between diabetes and diverse cancer progressions, examining molecular mechanisms and potential therapeutic intersections. From altered metabolic landscapes to dysregulated signaling pathways, the intricate links are delineated, offering a comprehensive understanding of diabetes as a modulator of tumorigenesis. Cancer cells develop drug resistance through mechanisms like enhanced drug efflux, genetic mutations, and altered drug metabolism, allowing them to survive despite chemotherapeutic agent. Glucose emerges as a pivotal player in diabetes progression, and serving as a crucial energy source for cancer cells, supporting their biosynthetic needs and adaptation to diverse microenvironments. Glycation, a non-enzymatic process that produces advanced glycation end products (AGEs), has been linked to the etiology of cancer and has been shown in a number of tumor forms, such as leiomyosarcomas, adenocarcinomas, and squamous cell carcinomas. Furthermore, in aggressive and metastatic breast cancer, the receptor for AGEs (RAGE) is increased, which may increase the malignancy of the tumor. Reprogramming glucose metabolism manifests as hallmark cancer features, including accelerated cell proliferation, angiogenesis, metastasis, and evasion of apoptosis. This manuscript encapsulates the dual narrative of diabetes as a driver of cancer progression and the potential of repurposed antidiabetic drugs as formidable countermeasures. The amalgamation of mechanistic understanding and clinical trial outcomes establishes a robust foundation for further translational research and therapeutic advancements in the dynamic intersection of diabetes and cancer.

Gut Microbiota Diversity and Composition Is Associated with High-Risk Myeloma

Background: High-dose melphalan conditioning followed by autologous stem cell transplantation (ASCT) is standard therapy for newly diagnosed multiple myeloma (MM) patients with standard-risk (SR) or high-HR disease. Despite significant improvements in the depth of response by induction therapy prior to ASCT and consolidation and maintenance therapy post-ASCT, most MM patients with HR cytogenetics relapse quickly post-ASCT with a median PFS ranging between 1 and 2 years. It remains unclear as to why patients identified as relapse earlier than those with SR disease (SR). We ask whether the variability in outcome is due to differences in the diversity and composition of the gut microbiome given its role as a predictor and modulator of tumorigenesis, anti-tumor immunity and response to therapy. Two preclinical studies have shown progression of MM is accelerated by a T H17-associated gut commensal (Calcinotto et al. Nat Commun, 2018) and nitrogen-cycling bacteria (Zhu et al. Microbiome, 2020). In MM patients, lower peri-engraftment diversity predicted inferior outcomes after ASCT (Khan et al. Blood, 2021) and sustained minimal residual disease-negativity was associated with butyrate-producing bacteria and plant-based diets (Shah et al. Clin Cancer Res, 2022). In this study, we analyzed the association between gut microbiota and HR cytogenetic features in MM patients in the ASCT setting. We also determined the cause-and-effect relationship between gut microbiota and disease progression in the 5TGM1 mouse model. Methods and Results: We prospectively collected stool samples from 55 MM patients at time of melphalan conditioning (pre-ASCT), engraftment (72hrs of absolute neutrophil count ≥ 500/mcL), and 60-120 days post-ASCT. The median age of patients (35 males, 20 females) was 63.1 (range 45.6-77.2) years. After a median follow-up of 54 months (range 1-81), the median PFS of patients was 37 months (range 1- 76). We profiled the gut microbiome of SR (n=29) and HR (n=26) MM patients using 16S rRNA sequencing of the V4-V5 region. Amplicon sequence variants (ASV) were annotated against the NCBI 16S database using BLAST. We chose to identify gut microbiota features associated with HR cytogenetics in samples during peri-engraftment when microbial dysbiosis and impaired immune function is most pronounced. The alpha diversity was higher in HR patients using Inverse Diversity index (p<0.020). However, we did not observe significant differences in beta-diversity between groups. Random forest prediction classifier method and Shapley Additive exPlanations (SHAP), a post-hoc explainability algorithm identified Schaalia, Streptococcus, Bifidobacterium with the highest variable of importance (Fig. 1A) These findings were further validated by linear discriminant analysis of effect size (LEfSe). To establish causality, we generated two isogenic C57BL/KaLwRij strains that harbor differences in the complexity and richness of naturally occurring gut microbiota, using complex microbiota targeted rederivation. We observed significant baseline differences in richness (p<0.001), β-diversity (Bray Curtis, p=0.0001), hierarchical clustering and relative abundance among GM1 (low richness), GM4 (intermediate richness) and our original (Orig) GM strain (high richness) bred in our vivarium. The median overall survival for MM-bearing GM1, GM4 Orig GM mice were 31, 35 and 39 days post-5TGM1 transplantation (Fig. 1B). Conclusions: These studies suggest that distinct gut microbiota signatures are associated with HR and SR disease. Furthermore, our preclinical findings suggest a causal relationship between gut microbiota and severity of disease further highlighting the influence of the gut microbiome on progression of disease. Taken together, these findings provide the rationale for microbiota-centered interventions to improve immune-mediated control of MM and overturn resistance to therapy.

The significance of glycolysis in tumor progression and its relationship with the tumor microenvironment.

It is well known that tumor cells rely mainly on aerobic glycolysis for energy production even in the presence of oxygen, and glycolysis is a known modulator of tumorigenesis and tumor development. The tumor microenvironment (TME) is composed of tumor cells, various immune cells, cytokines, and extracellular matrix, among other factors, and is a complex niche supporting the survival and development of tumor cells and through which they interact and co-evolve with other tumor cells. In recent years, there has been a renewed interest in glycolysis and the TME. Many studies have found that glycolysis promotes tumor growth, metastasis, and chemoresistance, as well as inhibiting the apoptosis of tumor cells. In addition, lactic acid, a metabolite of glycolysis, can also accumulate in the TME, leading to reduced extracellular pH and immunosuppression, and affecting the TME. This review discusses the significance of glycolysis in tumor development, its association with the TME, and potential glycolysis-targeted therapies, to provide new ideas for the clinical treatment of tumors.

Abstract PR017: Stromal Netrin G1 ligand (NGL-1): A new modulator of tumorigenesis and immunosuppression in pancreatic cancer

Abstract Pancreatic ductal adenocarcinoma (PDAC) is soon to be the second deadliest types of cancer, with a 5-year survival of only 10%. The unique features of PDAC are the expansion of cancer-associated fibroblasts (CAFs), presence of a dense fibrous stroma with high bundled collagen I and immunosuppression, representing a challenge for therapies. Ways to overcome these unique pro-tumor features will be key for the development of better therapeutic strategies for PDAC. Herein we report that, in addition to the identified ectopic expression of NGL-1 in PDAC cells, it is also expressed in the stroma (CAFs and immune cells) of PDAC patients, inversely correlating with overall survival. Stromal NGL-1 was important for tumorigenesis in vivo, as NGL-1 knockout mice (KO) orthotopically allografted with pancreatic cancer cells presented less tumor burden. Further analysis showed that the tumors from KO mice presented more CD8+ T cells and less immunosuppressive cytokines, such as TGFβ. Single cell RNAseq analysis of these tumors showed decreased expression of pro-tumor factors, such as immune checkpoint molecules in T cells and TGFβ related genes across different cellular compartments (epithelial, immune and fibroblasts). In accordance with these results, these tumors presented a limited amount of desmoplastic bundled collagen, suggestive of a TGFβ-deficient environment. In order to further dissect between the NGL-1-dependent contributions of immune vs. local stroma (e.g., CAFs) cells, we generated bone marrow chimeras and performed orthotopic injections to generate tumors. The loss of NGL-1 in each cellular compartment alone failed to phenocopy the full body loss of NGL-1, suggesting that NGL-1 in both immune cells and local stromal are important for tumorigenesis. Functionally, NGL-1 deficient CAFs failed to support the survival of starved PDAC cells in vitro, downregulated important myofibroblastic molecules such as p-smad, and produced less immunosuppressive cytokines, suggesting a role for NGL-1 in key pro-tumor features of CAFs. In fact, the fibroblastic NGL-1 dependent immunomodulatory effects were confirmed with human CD8+ T cells from healthy donors, which lost their cytotoxic profile in the presence of conditioned media (CM) from NGL-1+ CAFs, but were able to keep this profile when exposed to CM from NGL-1 deficient CAFs. Bone marrow derived macrophages from KO mice produced less pro-tumor cytokines and CD8+ T cells lacking NGL-1 proliferated more than those from wild type animals, when stimulated in vitro. Mechanistically, while immune cells and CAFs deficient in NGL-1 are both tumor suppressive, the latter can regain pro-tumor functions in response to TGFβ, explaining the need for a global modulation of NGL-1 expression for an anti-tumor effect. Finally, NGL-1 KO mice orthotopically allografted with PDAC cells responded better (smaller tumors) to chemotherapeutical regimen (FOLFIRINOX) compared to WT animals. All these results point to NGL-1 as a potential new target to modulate immunosuppression and tumorigenesis in pancreatic cancer. Citation Format: Debora Barbosa Vendramini Costa, Ralph Francescone, Janusz Franco-Barraza, Tiffany Luong, Esteban Martinez, Stephen Sykes, Nina Steele, Marina Pasca di Magliano, Dmitry Zhigarev, Charline Ogier, Huamin Wang, Igor Astsaturov, Kerry Campbell, Edna Cukierman. Stromal Netrin G1 ligand (NGL-1): A new modulator of tumorigenesis and immunosuppression in pancreatic cancer [abstract]. In: Proceedings of the AACR Special Conference on Pancreatic Cancer; 2022 Sep 13-16; Boston, MA. Philadelphia (PA): AACR; Cancer Res 2022;82(22 Suppl):Abstract nr PR017.

LncRNA RSU1P2-microRNA let-7a-Testis-Expressed Protein 10 axis modulates tumorigenesis and cancer stem cell-like properties in liver cancer

ABSTRACT LncRNAs exert important functions in the modulation of tumorigenesis and cancer stem cell-like properties in liver cancer. However, the role of LncRNA Ras suppressor protein 1 pseudogene 2 (RSU1P2) in modulating tumorigenesis and cancer stem cell-like properties in liver cancer is still not known. In this study, the expression of LncRNA RSU1P2 was significantly elevated in liver cancer tissues and cells. Besides, knockdown of RSU1P2 repressed cell viability, invasion, epithelial-mesenchymal transition (EMT) of liver cancer cells and the expressions of cancer stem cell-related genes, whereas facilitated the apoptosis of liver cancer cells. In addition, LncRNA RSU1P2 can interact with microRNA let-7a (let-7a), and repress let-7a expression. Testis-Expressed Protein 10 (Tex10) was identified to be a target of let-7a, and let-7a repressed Tex10 expression. Finally, RSU1P2 knockdown suppressed tumor volume, tumor weight, and EMT in a xenograft model. Therefore, LncRNA RSU1P2 promotes tumorigenesis and cancer stem cell-like properties in liver cancer through let-7a/Tex10 pathway.

Role of Bioactive Constituents of Panax notoginseng in the Modulation of Tumorigenesis: A Potential Review for the Treatment of Cancer.

Cancer is a leading cause of death, affecting people in both developed and developing countries. It is a challenging disease due to its complicated pathophysiological mechanism. Many anti-cancer drugs are used to treat cancer and reduce mortality rates, but their toxicity limits their administration. Drugs made from natural products, which act as multi-targeted therapy, have the ability to target critical signaling proteins in different pathways. Natural compounds possess pharmacological activities such as anti-cancer activity, low toxicity, and minimum side effects. Panax notoginseng is a medicinal plant whose extracts and phytochemicals are used to treat cancer, cardiovascular disorders, blood stasis, easing inflammation, edema, and pain. P. notoginseng’s secondary metabolites target cancer’s dysregulated pathways, causing cancer cell death. In this review, we focused on several ginsenosides extracted from P. notoginseng that have been evaluated against various cancer cell lines, with the aim of cancer treatment. Furthermore, an in vivo investigation of these ginsenosides should be conducted to gain insight into the dysregulation of several pathways, followed by clinical trials for the potential and effective treatment of cancer.

Silencing of miR-182 is associated with modulation of tumorigenesis through apoptosis induction in an experimental model of colorectal cancer

BackgroundmiR-182-5p (miR-182) is an oncogenic microRNA (miRNA) found in different tumor types and one of the most up-regulated miRNA in colorectal cancer (CRC). Although this microRNA is expressed in the early steps of tumor development, its role in driving tumorigenesis is unclear.MethodsThe effects of miR-182 silencing on transcriptomic profile were investigated using two CRC cell lines characterized by different in vivo biological behavior, the MICOL-14h-tert cell line (dormant upon transfer into immunodeficient hosts) and its tumorigenic variant, MICOL-14tum. Apoptosis was studied by annexin/PI staining and cleaved Caspase-3/PARP analysis. The effect of miR-182 silencing on the tumorigenic potential was addressed in a xenogeneic model of MICOL-14tum transplant.ResultsEndogenous miR-182 expression was higher in MICOL-14tum than in MICOL-14h-tert cells. Interestingly, miR-182 silencing had a strong impact on gene expression profile, and the positive regulation of apoptotic process was one of the most affected pathways. Accordingly, annexin/PI staining and caspase-3/PARP activation demonstrated that miR-182 treatment significantly increased apoptosis, with a prominent effect in MICOL-14tum cells. Moreover, a significant modulation of the cell cycle profile was exerted by anti-miR-182 treatment only in MICOL-14tum cells, where a significant increase in the fraction of cells in G0/G1 phases was observed. Accordingly, a significant growth reduction and a less aggressive histological aspect were observed in tumor masses generated by in vivo transfer of anti-miR-182-treated MICOL-14tum cells into immunodeficient hosts.ConclusionsAltogether, these data indicate that increased miR-182 expression may promote cell proliferation, suppress the apoptotic pathway and ultimately confer aggressive traits on CRC cells.

Abstract 1515: Removal of innate suppressors facilitates tumor-immune surveillance

Abstract Although tumor immune environment is increasingly recognized to be highly important during the modulation of tumorigenesis and tumor regression, the role and regulation of innate leukocytes such as neutrophils during the modulation of tumor immune environment remain controversial and less defined. In this study, we tested the hypothesis that removal of innate signaling suppressors may boost the anti-tumor immune function of innate neutrophils in vitro and in vivo. To this regard, we examined two key innate signaling suppressors Tollip and IRAK-M and their roles in modulating neutrophil anti-tumor immune functions. We observed that selective deletion of Tollip enhanced tumor immune surveillance in the AOM-DSS chemically induced colon cancer model. Tollip deficiency released the neutrophil suppression on T cell proliferation and activation. The adoptive transfer of Tollip deficient neutrophils were sufficient to transfer enhanced tumor immune surveillance and reduce tumor burden. Likewise, the study of another innate suppressor IRAK-M revealed that IRAK-M expression was up-regulated in the human patients with colorectal cancer. We also demonstrated that IRAK-M deficient mice exhibited reduced tumor burden following AOM-DSS challenge. Together, our data reveal a novel anti-tumor immune-enhancement strategy through utilizing reprogrammed neutrophils with targeted removal of innate signaling suppressors. Citation Format: Yao Zhang, Christina Lee, Na Diao, Liwu Li. Removal of innate suppressors facilitates tumor-immune surveillance [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 1515.

Inhibition of BAP31 expression inhibits cervical cancer progression by suppressing metastasis and inducing intrinsic and extrinsic apoptosis

Cervical cancer is reported as one of the most lethal types of cancer among female. However, extensive studies of the molecular mechanisms that regulate the progression of cervical cancer are still required. B-cell associated protein (BAP)-31 is a 28-kDa integral membrane protein in the endoplasmic reticulum (ER), playing essential role in modulating various physiological processes. The present study indicated that BAP31 was a novel gene associated with cervical cancer development. Here, we demonstrated that BAP31 was significantly increased in human cervical cancer specimens, which was positively correlated to histological grade of the cancer. BAP31 knockdown suppressed cell proliferation, clonogenic ability and metastasis-associated traits in vitro, as well as carcinogenesis and pulmonary metastasis in vivo. Further studies indicated that the expression levels of transforming growth factor (TGF)-β1, matrix metalloproteinase (MMP)-2, MMP-9, Rho-associated protein kinase 1 (ROCK1), α-smooth muscle actin (α-SMA), Vimentin and N-cadherin were markedly reduced by BAP31 knockdown in cervical cancer cells. In addition, intrinsic and extrinsic apoptosis was significantly induced in BAP31 knockdown cells, as evidenced by the increased expression of cleaved Caspase-8/-9/-3 and poly (ADP-ribose) polymerases (PARP). Notably, suppressing the activities of Caspase-8/-9 and −3 obviously diminished BAP31 silence-triggered apoptosis. Together, these findings highlighted an essential role for BAP31 in the modulation of tumorigenesis and metastatic potential of cervical cancer, and demonstrated a promising application of BAP31 in cancer prevention.

Abstract 4557: Tip110-mediated regulation of NF-κB activity is key to tumorigenesis

Abstract HIV-1 Tat-interacting protein (Tip110), also known as squamous cell carcinoma antigen recognized by T cells 3 (SART3), is a multifaceted nuclear protein and has been shown to function in tumor antigenicity. Tip110 protein expression is very low in normal tissues and non-proliferating cells but becomes highly elevated in a number of malignant tumor cell lines and cancerous tissues, pointing to its possible role in tumorigenesis. Our previous studies have shown that Tip110 specifically interacted with oncogenic deubiquitinating enzyme, USP15, and that ectopic expression of the Tip110 protein led to re-distribution of USP15 from the cytoplasm to the nucleus. USP15 is known to inhibit TNF-α-induced NF-κB activity by modulation of IκB-α ubiquitination. In the current study, we demonstrated that Tip110 augmented TNF-α-induced transcription activity of NF-κB, and that deletion of the nuclear localization domain in Tip110 obliterated the observed enhancement of TNF-α-induced NF-κB activity, providing the very first evidence to support the specific role of Tip110 in NF-κB activation. In addition, we found that Tip110 expression modulated IκB-α phosphorylation and that activation of NF-κB by Tip110 was mediated through the p38/MAPK pathway. Moreover, we showed that ectopic expression of Tip110 induced translocation of NF-κB p65 from the cytoplasm to the nucleus, reminiscent of the aforementioned translocation of USP15, in the absence of direct interaction of Tip110 with either p65 or IκB-α. Taken together, these results indicate that opposing regulation of TNFα-induced NF-κB activity by Tip110 and USP15 could be pivotal for modulation of tumorigenesis. Further delineation of the underlying signaling cascades will likely provide new insights into development of anti-tumor agents. Citation Format: Khalid Amine Timani, Amanda Whitmill, Ying Liu, Johnny J. He. Tip110-mediated regulation of NF-κB activity is key to tumorigenesis. [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 4557.

Modulation of tumorigenesis by the pro-inflammatory microRNA miR-301a in mouse models of lung cancer and colorectal cancer.

Lung cancer and colorectal cancer account for over one-third of all cancer deaths in the United States. MicroRNA-301a (miR-301a) is an activator of both nuclear factor-κB (NF-κB) and Stat3, and is overexpressed in both deadly malignancies. In this work, we show that genetic ablation of miR-301a reduces Kras-driven lung tumorigenesis in mice. And miR-301a deficiency protects animals from dextran sodium sulfate-induced colon inflammation and colitis-associated colon carcinogenesis. We also demonstrate that miR-301a deletion in bone marrow-derived cells attenuates tumor growth in the colon carcinogenesis model. Our findings ascertain that one microRNA—miR-301a—activates two major inflammatory pathways (NF-κB and Stat3) in vivo, generating a pro-inflammatory microenvironment that facilitates tumorigenesis.

Modulation of tumorigenesis by dietary intervention is not mediated by SIRT1 catalytic activity.

The protein deacetylase SIRT1 is involved in the regulation of a large number of cellular processes that are thought to be required for cancer initiation and progression. Both SIRT1 activity and tumorigenesis can be influenced by dietary fat and polyphenolics. We set out to determine whether dietary modulations of tumorigenesis are mediated by SIRT1 catalytic functions. We introduced a mammary gland tumor-inducing transgene, MMTV-PyMT, into stocks of mice bearing a H355Y point mutation in the Sirt1 gene that abolishes SIRT1 catalytic activity. Tumor latency was reduced in animals fed a high fat diet but this effect was not dependent on SIRT1 activity. Resveratrol had little effect on tumor formation except in animals heterozygous for the mutant Sirt1 gene. We conclude that the effects of these dietary interventions on tumorigenesis are not mediated by modulation of SIRT1 catalytic activity.

Roles of integrin-linked kinase in cell signaling and its perspectives as a therapeutic target

Abstract Integrin-linked kinase (ILK) localizes to focal adhesions, and interacts with the cytoplasmic tail of β subunits of integrins and couples them to the actin cytoskeleton. ILK may act as a kinase and transmit the signals in a phosphatidylinositol 3-kinase-dependent manner, or can act as a scaffold protein to function through cell–matrix interactions, cell signaling, and cytoskeletal organization. Within this pivotal position, ILK mediates many important cellular processes, including survival, proliferation, differentiation, adhesion, migration, contractility, etc. Besides, ILK plays some role in the activation of endothelial progenitor cells and neovascularization, and may also enhance vascular endothelial growth factor expression. Increased ILK activity may promote epithelial-to-mesenchymal transition and induce a transformed, tumorigenic phenotype. Higher expression of ILK was frequently noted in human malignancies. ILK may also be important for mitotic-spindle assembly. Inhibition of ILK causes proliferative defects, induces cell-cycle arrest and apoptosis, and is embryonically lethal. New concepts of gene or cell-based therapy working on the up- or downregulation of ILK have emerged as a valid therapeutic approach for cancer treatment, and also a new hope for vasculogenesis in the ischemic area. The current review will discuss some known mechanisms, and the role of ILK in the modulation of tumorigenesis and reproduction, based on an extensive literature survey.

Lack of High-Dose Radiation Mediated Prostate Cancer Promotion and Low-Dose Radiation Adaptive Response in the TRAMP Mouse Model

Cancer of the prostate is a highly prevalent disease with a heterogeneous aetiology and prognosis. Current understanding of the biological mechanisms underlying the responses of prostate tissue to ionizing radiation exposure, including cancer induction, is surprisingly limited for both high- and low-dose exposures. As population exposure to radiation increases, largely through medical imaging, a better understanding of the response of the prostate to radiation exposure is required. Low-dose radiation-induced adaptive responses for increased cancer latency and decreased cancer frequency have been demonstrated in mouse models, largely for hematological cancers. This study examines the effects of high- and low-dose whole-body radiation exposure on prostate cancer development using an autochthonous mouse model of prostate cancer: TRansgenic Adenocarcinoma of the Mouse Prostate (TRAMP). TRAMP mice were exposed to single acute high (2 Gy), low (50 mGy) and repeated low (5 × 50 mGy) doses of X rays to evaluate both the potential prostate cancer promoting effects of high-dose radiation and low-dose adaptive response phenomena in this prostate cancer model. Prostate weights and histopathology were examined to evaluate gross changes in cancer development and, in mice exposed to a single 2 Gy dose, time to palpable tumor was examined. Proliferation (Ki-67), apoptosis, DNA damage (γ-H2AX) and transgene expression (large T-antigen) were examined within TRAMP prostate sections. Neither high- nor low-dose radiation-induced effects on prostate cancer progression were observed for any of the endpoints studied. Lack of observable effects of high- or low-dose radiation exposure suggests that modulation of tumorigenesis in the TRAMP model is largely resistant to such exposures. However, further study is required to better assess the effects of radiation exposure using alternative prostate cancer models that incorporate normal prostate and in those that are not driven by SV40 large T antigen.

Simultaneously expressed miR-424 and miR-381 synergistically suppress the proliferation and survival of renal cancer cells—Cdc2 activity is up-regulated by targeting WEE1

OBJECTIVES:MiRNAs are intrinsic RNAs that interfere with protein translation. Few studies on the synergistic effects of miRNAs have been reported. Both miR-424 and miR-381 have been individually reported to be involved in carcinogenesis. They share a common putative target, WEE1, which is described as an inhibitor of G2/M progression. Here, we studied the synergistic effects of miR-424 and miR-381 on renal cancer cells.METHODS:The viability of 786-O cells was analyzed after transfection with either a combination of miR-424 and miR-381 or each miRNA alone. We investigated cell cycle progression and apoptosis with flow cytometry. To confirm apoptosis and the abrogation of G2/M arrest, we determined the level of pHH3, which is an indicator of mitosis, and caspase-3/7 activity. The expression levels of WEE1, Cdc25, γH2AX, and Cdc2 were manipulated to investigate the roles of these proteins in the miRNA-induced anti-tumor effects. To verify that WEE1 was a direct target of both miR-424 and miR-381, we performed a dual luciferase reporter assay.RESULTS:We showed that the combination of these miRNAs synergistically inhibited proliferation, abrogated G2/M arrest, and induced apoptosis. This combination led to Cdc2 activation through WEE1 inhibition. This regulation was more effective when cells were treated with both miRNAs than with either miRNA alone, indicating synergy between these miRNAs. WEE1 was verified to be a direct target of each miRNA according to the luciferase reporter assay.CONCLUSIONS:These data clearly demonstrate that these two miRNAs might synergistically act as novel modulators of tumorigenesis by down-regulating WEE1 expression in renal cell cancer cells.

Mo2079 Tff2 Is a Novel Tumor Suppressor That Inhibits Expansion of Gr1+CD11b+ Myeloid-Derived Suppressor Cells and Blocks Colon Carcinogenesis

Trefoil factor 2 (Tff2) is a small, secreted protein expressed in gastrointestinal mucosa where it functions to protect and repair mucosa. It is, however, also expressed at low levels in splenic immune cells, where its role has been unclear. Tff2 is epigenetically silenced in gastric cancer and thus has been postulated to protect against cancer development through multiple mechanisms. Because Tff2 is normally expressed in splenic T cells, we investigated the specific contribution of T-cell–related Tff2 production in the modulation of tumorigenesis.

DUSPs, to MAP kinases and beyond

Phosphatases are important regulators of intracellular signaling events, and their functions have been implicated in many biological processes. Dual-specificity phosphatases (DUSPs), whose family currently contains 25 members, are phosphatases that can dephosphorylate both tyrosine and serine/threonine residues of their substrates. The archetypical DUSP, DUSP1/MKP1, was initially discovered to regulate the activities of MAP kinases by dephosphorylating the TXY motif in the kinase domain. However, although DUSPs were discovered more than a decade ago, only in the past few years have their various functions begun to be described. DUSPs can be categorized based on the presence or absence of a MAP kinase-interacting domain into typical DUSPs and atypical DUSPs, respectively. In this review, we discuss the current understanding of how the activities of typical DUSPs are regulated and how typical DUSPs can regulate the functions of their targets. We also summarize recent findings from several in vivo DUSP-deficient mouse models that studied the involvement of DUSPs during the development and functioning of T cells. Finally, we discuss briefly the potential roles of DUSPs in the regulation of non-MAP kinase targets, as well as in the modulation of tumorigenesis.

Abstract 3795: Mitochondrial complex I modulation regulates autophagy and breast cancer progression

Abstract Tumor cells express altered metabolic activities often linked to mitochondrial dysfunction. Such mitochondrial defects can inhibit oxidative phosphorylation, change the cellular redox state (NAD+/NADH), increase production of reactive oxygen species (ROS), and cause DNA damage that further supports tumorigenesis and a metastatic phenotype. Our study identified mitochondrial complex I (NADH dehydrogenase) as a modulator of tumorigenesis and metastatic progression in breast cancer. We used NDI1, the NADH dehydrogenase from yeast, to augment complex I activity in metastatic human breast cancer cells. The NDI1 protein is known to integrate into the inner mitochondrial membrane of mammalian cells, function as NADH dehydrogenase, pass electrons into the respiratory chain, and thereby fully augment intrinsic complex I activity. Thus, NDI1 identifies critical involvement of complex I NADH dehydrogenase activity in cellular functions that are altered upon its expression. We investigated a panel of aggressive human breast cancer cell lines, including MDA-MB 231, and found that augmentation of NADH dehydrogenase activity through NDI1 resulted in an enhanced NAD+/NADH ratio and inhibition of ROS production. Most importantly, NDI1 expression inhibited metastasis and tumor growth in the mammary fad pad of immune deficient mice, seen by non-invasive imaging and histology. The same effects were achieved by treatment with NAD precursors, demonstrating that normalization of the NAD+/NADH ratio is critical for inhibition of breast cancer progression. We found that the underlying mechanism is based on activation of PTEN, inhibition of the AKT/mTOR survival pathway, and stimulation of autophagy. Autophagy is responsible for NDI1-mediated inhibition of breast cancer progression, as knock-down of ATG5 reversed the anti-metastatic effect of NDI1. Our results demonstrate that tumorigenesis and metastasis in breast cancer are critically influenced by mitochondrial complex I activity. We show that augmentation of tumor cell complex I function can interfere with tumor formation and breast cancer spreading through modulating the NAD+/NADH ratio. Thus, normalization of complex I function appears as a promising new target for prevention and treatment of breast progression. 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 3795. doi:10.1158/1538-7445.AM2011-3795

Modulation of tumorigenesis and oestrogen receptor-α expression by cell culture conditions in a stem cell-derived breast epithelial cell line

The common phenotypes of cancer and stem cells suggest that cancers arise from stem cells. Oestrogen is one of the few most important determinants of breast cancer, as shown by several lines of convincing evidence. We have previously reported a human breast epithelial cell type (Type 1 HBEC) with stem cell characteristics and ER alpha (oestrogen receptor alpha) expression. A tumorigenic cell line, M13SV1R2, was developed from this cell type after SV40 (simian virus 40) large T-antigen transfection and X-ray irradiation. The cell line, however, was not responsive to oestrogen for cell growth or tumour development. In the present study, we tested the hypothesis that deprivation of growth factors and hormones may change the tumorigenicity and oestrogen response of this cell line. The M13SV1R2 cells lost their tumorigenicity after culturing in a growth factor/hormone-deprived medium for >10 passages (referred to as R2d cells) concomitant with the expression of two tumour suppressor genes, namely those coding for maspin and alpha 6 integrin. However, these cells acquired oestrogen responsiveness in cell growth and tumour development. By immunocytochemistry, Western blotting and flow cytometry analysis, oestrogen treatment of R2d cells was found to induce many important effects related to breast carcinogenesis, namely: (i) the emergence of a subpopulation of cells expressing CD44+/high/CD24-/low breast tumour stem cell markers; (ii) the induction of EMT (epithelial-to-mesenchymal transition); (iii) the acquisition of metastatic ability; and (iv) the expression of COX-2 (cyclo-oxygenase-2) through a CD44-mediated mechanism. An oestrogen-responsive cell line with ER alpha and CD44+/CD24-/low expression can be derived from breast epithelial stem cells. The tumorigenicity and oestrogen response of these cells could depend on the cell culture conditions. The findings of this study have implications in regard to the origins of (1) ER alpha-positive breast cancers, (2) CD44+/CD24-/low breast tumour stem cells and (3) the metastatic ability of breast cancer.

Polyamine metabolism and tumorigenesis in the Apc Min/+ mouse

While polyamine homoeostasis is clearly important in maintenance of normal cell function, the roles of these cations, as well as the enzymes that regulate their metabolism, in the neoplastic process are not clear. In particular, the polyamine catabolic enzyme SSAT (spermidine/spermine N(1)-acetyltransferase) seems to have different roles in tumorigenesis, depending upon the particular system being analysed. In attempts to clarify the function of SSAT in tumour development, we have utilized the Apc(Min/+) mouse, which carries a mutant allele of the Apc (adenomatous polyposis coli) gene, rendering it susceptible to the formation of multiple adenomas in the small intestine and colon. Using genetically engineered animals (i.e. transgenic and knockout mice), we have shown that SSAT acts as a tumour promoter in the Apc(Min/+) model. Modulation of tumorigenesis is not associated with changes in tissue levels of either spermidine or spermine. These findings, along with those made in other animal models of cancer, have prompted us to propose that metabolic flux through the polyamine biosynthetic and catabolic pathways, and the consequent changes in levels of various metabolites within the cell (i.e. the metabolome), is critical to tumour development. The metabolic flux model represents a novel way of thinking about the role of polyamines in cell physiology and the neoplastic process.