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Screening for sensitizers of cancer cells to TRAIL-mediated apoptosis identified a natural product of the 17β-hydroxywithanolide (17-BHW) class, physachenolide C (PCC), as a promising hit. In this study, we show that PCC was also able to sensitize melanoma and renal carcinoma cells to apoptosis in response not only to TRAIL, but also to the synthetic polynucleotide poly I:C, a viral mimetic and immune activator, by reducing levels of antiapoptotic proteins cFLIP and Livin. Both death receptor and TLR3 signaling elicited subsequent increased assembly of a proapoptotic ripoptosome signaling complex. Administration of a combination of PCC and poly I:C in human M14 melanoma xenograft and a syngeneic B16 melanoma model provided significant therapeutic benefit as compared with individual agents. In addition, PCC enhanced melanoma cell death in response to activated human T cells in vitro and in vivo in a death ligand–dependent manner. Biochemical mechanism-of-action studies established bromo and extraterminal domain (BET) proteins as major cellular targets of PCC. Thus, by targeting of BET proteins to reduce antiapoptotic proteins and enhance caspase-8–dependent apoptosis of cancer cells, PCC represents a unique agent that can potentially be used in combination with various immunotherapeutic approaches to promote tumor regression and improve outcome.Significance:These findings demonstrate that PCC selectively sensitizes cancer cells to immune-mediated cell death, potentially improving the efficacy of cancer immunotherapies.

Supplementary Materials & Methods, Supplementary Figures 1-10 with Figure Legends

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Supplementary Figure 2 from Coactivation of AKT and β-Catenin in Mice Rapidly Induces Formation of Lipogenic Liver Tumors

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Supplementary Figure 1 from Coactivation of AKT and β-Catenin in Mice Rapidly Induces Formation of Lipogenic Liver Tumors

Supplementary Figure 5 from Coactivation of AKT and β-Catenin in Mice Rapidly Induces Formation of Lipogenic Liver Tumors

Supplementary Figure 6 from Coactivation of AKT and β-Catenin in Mice Rapidly Induces Formation of Lipogenic Liver Tumors

Screening for sensitizers of cancer cells to TRAIL-mediated apoptosis identified a natural product of the 17β-hydroxywithanolide (17-BHW) class, physachenolide C (PCC), as a promising hit. In this study, we show that PCC was also able to sensitize melanoma and renal carcinoma cells to apoptosis in response not only to TRAIL, but also to the synthetic polynucleotide poly I:C, a viral mimetic and immune activator, by reducing levels of antiapoptotic proteins cFLIP and Livin. Both death receptor and TLR3 signaling elicited subsequent increased assembly of a proapoptotic ripoptosome signaling complex. Administration of a combination of PCC and poly I:C in human M14 melanoma xenograft and a syngeneic B16 melanoma model provided significant therapeutic benefit as compared with individual agents. In addition, PCC enhanced melanoma cell death in response to activated human T cells in vitro and in vivo in a death ligand–dependent manner. Biochemical mechanism-of-action studies established bromo and extraterminal domain (BET) proteins as major cellular targets of PCC. Thus, by targeting of BET proteins to reduce antiapoptotic proteins and enhance caspase-8–dependent apoptosis of cancer cells, PCC represents a unique agent that can potentially be used in combination with various immunotherapeutic approaches to promote tumor regression and improve outcome. Significance: These findings demonstrate that PCC selectively sensitizes cancer cells to immune-mediated cell death, potentially improving the efficacy of cancer immunotherapies.

Triple-negative breast cancer (TNBC) accounts for 15-20% of all breast cancers. In order to develop the most effective treatment against TNBC, we tested the effects of the combination treatment with indomethacin and radiation on TNBC utilizing a mouse experimental TNBC equivalent model. Seven weeks old BALB/c mice were implanted with 4T1 mice triple-negative mammary gland tumor cells on the right hind leg one week before the treatments started. Mice were divided into four groups treated with vehicle control, 6 Gy radiation, 30 mg/L (in water) indomethacin, or combination regime of 6 Gy radiation and 30 mg/L indomethacin. 6 Gy radiation was given to mice on Day 0 only while indomethacin was given to mice every day. Mice received the combination treatment with radiation and indomethacin showed a significant tumor growth delay at the end of the treatment regime (Day 30). We next elucidated if there are changes in biological pathways during the early phase of combination therapy (Day 3). Total RNAs isolated from the primary tumors were subjected to whole genome transcriptomic analyses (RNAseq). We identified a total of 58 genes with 2-fold changes in expression and p-value Citation Format: Robert Yuk Sing Cheng, Lisa Ridnour, Timothy Back, Debashree Basudhar, Stephen Anderson, Daniel McVicar, David Wink. Identification of differentially expressed genes in 4T1 mice triple-negative mammary gland cancer during the early phase of combination treatment with indomethacin and radiation [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 3608.

Background & Aims Liver inflammatory diseases associated with cancer promoting somatic oncogene mutations are increasing in frequency. Preclinical cancer models that allow for the study of early tumor progression are often protracted, which limits the experimental study parameters due to time and expense. Here we report a robust inexpensive approach using Sleeping Beauty transposition (SBT) delivery of oncogenes along with Gaussia Luciferase expression vector GLuc, to assess de novo liver tumor progression, as well as the detection of innate immune responses or responses induced by therapeutic intervention. Methods Tracking de novo liver tumor progression with GLuc was demonstrated in models of hepatocellular carcinoma (HCC) or adenoma (HCA) initiated by hydrodynamic delivery of SBT oncogenes. Results Rising serum luciferase levels correlated directly with increasing liver tumor burden and eventual morbidity. Early detection of hepatocyte apoptosis from mice with MET+CAT transfected hepatocytes was associated with a transient delay in HCC growth mediated by a CD8 + T-cell response against transformed hepatocytes. Furthermore, mice that lack B cells or macrophages had an increase in TUNEL + hepatocytes following liver MET transfection demonstrating that these cells provide protection from MET-induced hepatocyte apoptosis. Treatment with IL-18+IL-12 of mice displaying established HCC decreased tumor burden which was associated with decreased levels of serum luciferase. Conclusions Hydrodynamic delivery of the SBT vector GLuc to hepatocytes serves as a simple blood-based approach for real-time tracking of pathologically distinct types of liver cancer. This revealed tumor-induced immunologic responses and was beneficial in monitoring the efficacy of therapeutic interventions.

Objectives The relative contributions of inflammatory signalling and sequential oncogenic dysregulation driving liver cancer pathogenesis remain incompletely understood. Lymphotoxin-β receptor (LTβR) signalling is critically involved in hepatitis and liver tumorigenesis. Therefore, we explored the interdependence of inflammatory lymphotoxin signalling and specific oncogenic pathways in the progression of hepatic cancer. Design Pathologically distinct liver tumours were initiated by hydrodynamic transfection of oncogenic V-Akt Murine Thymoma Viral Oncogene Homolog 1 (AKT)/β-catenin or AKT/Notch expressing plasmids. To investigate the relationship of LTβR signalling and specific oncogenic pathways, LTβR antagonist (LTβR-Fc) or agonist (anti-LTβR) were administered post oncogene transfection. Initiated livers/tumours were investigated for changes in oncogene expression, tumour proliferation, progression, latency and pathology. Moreover, specific LTβR-mediated molecular events were investigated in human liver cancer cell lines and through transcriptional analyses of samples from patients with intrahepatic cholangiocarcinoma (ICC). Results AKT/β-catenin-transfected livers displayed increased expression of LTβ and LTβR, with antagonism of LTβR signalling reducing tumour progression and enhancing survival. Conversely, enforced LTβR-activation of AKT/β-catenin-initiated tumours induced robust increases in proliferation and progression of hepatic tumour phenotypes in an AKT-dependent manner. LTβR-activation also rapidly accelerated ICC progression initiated by AKT/Notch, but not Notch alone. Moreover, LTβR-accelerated development coincides with increases of Notch, Hes1, c-MYC, pAKT and β-catenin. We further demonstrate LTβR signalling in human liver cancer cell lines to be a regulator of Notch, pAKTser473 and β-catenin. Transcriptome analysis of samples from patients with ICC links increased LTβR network expression with poor patient survival, increased Notch1 expression and Notch and AKT/PI3K signalling. Conclusions Our findings link LTβR and oncogenic AKT signalling in the development of ICC.

MIF is a proinflammatory cytokine and is implicated in cancer. A higher MIF level is found in many human cancer and cancer-prone inflammatory diseases, including chronic pancreatitis and pancreatic cancer. We tested the hypothesis that MIF contributes to pancreatic cancer aggressiveness and predicts disease outcome in resected cases. Consistent with our hypothesis we found that an elevated MIF mRNA expression in tumors was significantly associated with poor outcome in resected cases. Multivariate Cox-regression analysis further showed that MIF is independently associated with patients' survival (HR = 2.26, 95% CI = 1.17-4.37, p = 0.015). Mechanistic analyses revealed that MIF overexpression decreased E-cadherin and increased vimentin mRNA and protein levels in pancreatic cancer cell lines, consistent with the features of epithelial-to-mesenchymal transition (EMT). Furthermore, MIF-overexpression significantly increased ZEB1/2 and decreased miR-200b expression, while shRNA-mediated inhibition of MIF increased E-cadherin and miR-200b expression, and reduced the expression of ZEB1/2 in Panc1 cells. Re-expression of miR-200b in MIF overexpressing cells restored the epithelial characteristics, as indicated by an increase in E-cadherin and decrease in ZEB1/2 and vimentin expression. A reduced sensitivity to the chemotherapeutic drug, gemcitabine, occurred in MIF-overexpressing cells. Indicative of an increased malignant potential, MIF over-expressing cells showed significant increase in their invasion ability in vitro, and tumor growth and metastasis in an orthotopic xenograft mouse model. These results support a role of MIF in disease aggressiveness, indicating its potential usefulness as a candidate target for designing improved treatment in pancreatic cancer.

Using two MYCN transgenic mouse strains, we established 10 transplantable neuroblastoma cell lines via serial orthotopic passage in the adrenal gland. Tissue arrays demonstrate that by histochemistry, vascularity, immunohistochemical staining for neuroblastoma markers, catecholamine analysis, and concurrent cDNA microarray analysis, there is a close correspondence between the transplantable lines and the spontaneous tumors. Several genes closely associated with the pathobiology and immune evasion of neuroblastoma, novel targets that warrant evaluation, and decreased expression of tumor suppressor genes are demonstrated. These studies describe a unique and generalizable approach to expand the utility of transgenic models of spontaneous tumor, providing new tools for preclinical investigation.

IL-27 exerts antitumor activity in murine orthotopic neuroblastoma, but only partial antitumor effect in disseminated disease. This study demonstrates that combined treatment with IL-2 and IL-27 induces potent antitumor activity in disseminated neuroblastoma metastasis. Complete durable tumor regression was achieved in 90% of mice bearing metastatic TBJ-IL-27 tumors treated with IL-2 compared with only 40% of mice bearing TBJ-IL-27 tumors alone and 0% of mice bearing TBJ-FLAG tumors with or without IL-2 treatment. Comparable antitumor effects were achieved by IL-27 protein produced upon hydrodynamic IL-27 plasmid DNA delivery when combined with IL-2. Although delivery of IL-27 alone, or in combination with IL-2, mediated pronounced regression of neuroblastoma metastases in the liver, combined delivery of IL-27 and IL-2 was far more effective than IL-27 alone against bone marrow metastases. Combined exposure to IL-27 produced by tumor and IL-2 synergistically enhances the generation of tumor-specific CTL reactivity. Potentiation of CTL reactivity by IL-27 occurs via mechanisms that appear to be engaged during both the initial sensitization and effector phase. Potent immunologic memory responses are generated in mice cured of their disseminated disease by combined delivery of IL-27 and IL-2, and depletion of CD8+ ablates the antitumor efficacy of this combination. Moreover, IL-27 delivery can inhibit the expansion of CD4+CD25+Foxp3+ regulatory and IL-17-expressing CD4+ cells that are otherwise observed among tumor-infiltrating lymphocytes from mice treated with IL-2. These studies demonstrate that IL-27 and IL-2 synergistically induce complete tumor regression and long-term survival in mice bearing widely metastatic neuroblastoma tumors.

Nitric oxide (NO•), an important signaling molecule and a component of inflammatory response, is involved in tumorigenesis. However, the quantity of NO• and the cellular microenvironment influences the role of NO• in tumor development. We used a genetic strategy to test the hypothesis that an inflammatory microenvironment with an enhanced level of NO• accelerates spontaneous tumor development. C. parvum–induced inflammation and increased NO• synthase-2 (NOS2) expression coincided with accelerated spontaneous tumor development, mostly lymphomas, in p53−/−NOS2+/+ C57BL6 mice when compared with the controls (P = 0.001). However, p53−/−NOS2−/− mice did not show any difference in tumor latency between C. parvum–treated and control groups. In C. parvum–treated p53−/−NOS2+/+ mice, tumor development was preceded by a higher expression of NOS2 and phosphorylated Akt-Ser473 (pAkt-Ser473) in spleen, increased cell proliferation measured by Ki-67 IHC in spleen and thymus, and a lower apoptotic index and CD95-L expression in spleen and thymus. C. parvum–treated p53−/−NOS2+/+ mice showed an increase in the number of Foxp3(+) T-reg cells, dendritic cells (DC), as well as increased CD80+, CD86+, CD40+, and CD83+ on DC in the spleen. Regulatory T-cells (T-reg) and the maturation of DC may modulate tumorigenesis. An increase in the FoxP3(+)T-reg cells in C. parvum–treated p53−/−NOS2+/+ mice indicates a role of NO• in the regulation of T-reg cells that may contribute to a protumor shift of the immune environment favoring an accelerated tumor development. These data provide genetic and mechanistic evidence that an inflammatory microenvironment and an increased level of NO• can accelerate tumor development. [Cancer Res 2008;68(17):7130–6]

Analysis of the NK cell developmental pathway suggests that CD2 expression may be important in regulating NK maturation. To test this hypothesis, we developed mice containing only an inhibitory CD2 molecule by linking the extracellular domain of CD2 to an intracellular immunoreceptor tyrosine-based inhibitory motif (ITIM) motif. Mice containing the CD2 Tg(ITIM) transgene, introduced into a CD2 KO background, have no morphologically detectable lymph nodes, although development of the thymus appears normal. In addition, these mice had major loss of both NK and NKT subsets in peripheral organs, while T and B cell frequencies were intact. Expression of CD2 was low on T cells and lacking on B cells and functional defects were observed in these populations. NKT cells expressing CD4 were absent, while the CD8+ and double negative NKT cells were retained. Small subsets of NK cells were detected but expression of CD2 on these cells was very low or absent, and their maturation was impaired. Based on the phenotype described here, we believe that these mice represent a unique model to study lymphoid organ and lymphocyte development.

Protective cell-mediated immune responses in cancer are critically dependent on T-helper type 1 (T(H)1) cytokines such as interferon-gamma (IFN-gamma). We have previously shown that the combination of CD40 stimulation and interleukin-2 (IL-2) leads to synergistic antitumor responses in several models of advanced metastatic disease. We now report that after this treatment and other immunotherapy regimens, the CD4+ T-cell population, in contrast to CD8+ T cells, did not significantly increase but rather exhibited a substantial level of apoptosis that was dependent on IFN-gamma. Mice immunized with tumor cells and treated with an immunotherapy regimen that was initially protective were later unable to mount effective memory responses compared with immunized mice not receiving immunotherapy. Immunotherapy given to tumor-bearing Ifngr-/- mice resulted in restoration of secondary responses. Thus, although immunotherapeutic regimens inducing strong IFN-gamma responses can lead to successful early antitumor efficacy, they may also impair the development of durable antitumor responses.

The use of interleukin-18 (IL-18) together with IL-12 induced high levels of IFN-γ in tumor-bearing mice and regression of liver tumors that was abolished in IFN-γ(−/−) mice. Natural killer (NK) and NKT cells were the major producers of IFN-γ in the livers of mice treated with IL-18 and/or IL-12. Liver NK cells were significantly increased by treatment with IL-18/IL-12, whereas the degree of liver NKT cell TCR detection was diminished by this treatment. Reduction of NK cells with anti-asGM1 decreased the antitumor activity of IL-18/IL-12 therapy and revealed NK cells to be an important component for tumor regression in the liver. In contrast, the antitumor effects of both IL-18 and IL-12 were further increased in CD1d(−/−) mice, which lack NKT cells. Our data, therefore, show that the antitumor activity induced in mice by IL-18/IL-12 is NK and IFN-γ dependent and is able to overcome an endogenous immunosuppressive effect of NKT cells in the liver microenvironment. These results suggest that immunotherapeutic approaches that enhance NK cell function while eliminating or altering NKT cells could be effective in the treatment of cancer in the liver. (Cancer Res 2006; 66(22): 11005-12)

CD40, a member of the TNFR superfamily, is expressed on a variety of host immune cells, as well as some tumors. In this study, we show that stimulation of CD40 expressed on both mouse and human renal carcinoma cells (RCCs) triggers biological effects in vitro and in vivo. Treatment of the CD40+ Renca mouse RCC tumor cells in vitro with an agonistic anti-CD40 Ab induced strong expression of the genes and proteins for GM-CSF and MCP-1, and induced potent chemotactic activity. Similarly, administration of αCD40 to both wild-type and CD40−/− mice bearing Renca tumors resulted in substantial amounts of TNF-α and MCP-1 in the serum, increased the number of total splenocytes and MHC class II+ CD11c+ leukocytes, and when combined with IFN-γ, inhibited the progression of established Renca tumors in vivo in both wild-type and CD40−/− mice. Similarly, treatment of CD40+ A704 and ACHN human RCC lines with mouse anti-human CD40 Ab induced strong expression of genes and proteins for MCP-1, IL-8, and GM-CSF in vitro and in vivo. Finally, in SCID mice, the numbers of ACHN pulmonary metastases were dramatically reduced by treatment with species-specific human CD40 Ab. These results show that CD40 stimulation of CD40+ tumor cells can enhance immune responses and result in antitumor activity.

Lewis lung carcinoma (3LL) cells were constitutively resistant to Fas-mediated apoptosis, but overexpression of Fas on 3LL cells allowed Fas-mediated apoptosis after crosslinking with agonist anti-Fas antibody (Jo2) in vitro. Surprisingly, Fas-overexpressing 3LL cells showed enhanced in vivo tumor progression, whereas no promotion of in vivo tumor growth was observed for dominant negative (DN) Fas-overexpressing 3LL transfectants in which the cytoplasmic death domain was deleted. In addition, the promotion of in vivo tumor growth by Fas-overexpression was reduced in gld (FasL-mutation) mice compared to normal mice. These data indicate that intact Fas/FasL cell signaling is required for the promotion of in vivo tumor growth by Fas overexpression in 3LL cells. In contrast to the efficient Fas-mediated killing induced in vitro by crosslinking with anti-Fas antibody, Fas-overexpressing 3LL cells were resistant in vitro to Fas-mediated apoptosis by activated T cells or transient FasL transfection. These data suggest that agonist anti-Fas antibody and natural FasL can transmit qualitatively different signals, and crosslinking of Fas with natural FasL on 3LL cells does not deliver the expected death signal. Thus, our results demonstrate that in some cases overexpression of Fas can result in a survival advantage for tumor cells in vivo.

IFN-γ is a critical component of the endogenous and many cytokine-induced antitumor immune responses. In this study we have shown that the combination of IL-18 and IL-2 (IL-18/IL-2) synergistically enhances IFN-γ production both in vitro and in vivo, and synergizes in vivo to induce complete durable regression of well-established 3LL tumors in >80% of treated mice. We have observed a nascent, but ineffective, host immune response against 3LL that depends on endogenous IFN-γ and IL-12 production and the Fas/Fas ligand (Fas-L) pathway. The combined administration of IL-18/IL-2 engages this endogenous response to induce tumor regression via a mechanism that is independent of NK and NKT cells or IL-12, but is critically dependent on CD8+ T cells, IFN-γ, and the Fas/Fas-L pathway. These studies demonstrate the importance of IFN-γ as well as the Fas/Fas-L pathway in both endogenous and cytokine-driven antitumor immune responses engaged by IL-18/IL-2 and provide preclinical impetus for clinical investigation of this potent anti-tumor combination.

The role of Fas in the regulation of solid tumor growth was investigated. Murine renal carcinoma (Renca) cells were constitutively resistant to Fas-mediated killing in vitro, but exhibited increased expression of Fas and sensitivity to Fas-mediated killing after exposure to IFN-γ and TNF. Transfected Renca cells overexpressing Fas were efficiently killed in vitro upon exposure to anti-Fas Ab (Jo2). When Fas-overexpressing Renca cells were injected into syngenic BALB/c mice, there was a consistent and significant delay in tumor progression, reduced metastasis, and prolonged survival that was not observed for Renca cells that overexpressed a truncated nonfunctional Fas receptor. The delay of in vivo tumor growth induced by Fas overexpression was not observed in IFN-γ−/− mice, indicating that IFN-γ is required for the delay of in vivo tumor growth. However, there was a significant increase of infiltrated T cells and in vivo apoptosis in Fas-overexpressing Renca tumors, and Fas-overexpressing Renca cells were also efficiently killed in vitro by T cells. In addition, a strong therapeutic effect was observed on Fas-overexpressing tumor cells by in vivo administration of anti-Fas Ab, confirming that overexpressed Fas provides a functional target in vivo for Fas-specific ligands. Therefore, our findings demonstrate that Fas overexpression on solid tumor cells can delay tumor growth and provides a rationale for therapeutic manipulation of Fas expression as a means of inducing tumor regression in vivo.

Mice deficient in lymphotoxin (LT)-α lack peripheral lymph nodes and Peyer’s patches and have profound defects in development of follicular dendritic cell networks, germinal center formation, and T/B cell segregation in the spleen. Although LTα is known to be expressed by NK cells as well as T and B lymphocytes, the requirement of LTα for NK cell functions is largely unknown. To address this issue, we have assessed NK cell functions in LTα-deficient mice by evaluating tumor models with known requirements for NK cells to control their growth and metastasis. Syngeneic B16F10 melanoma cells inoculated s.c. grew more rapidly in LTα−/− mice than in the wild-type littermates, and the formation of experimental pulmonary metastases was significantly enhanced in LTα−/− mice. Although LTα−/− mice exhibited almost a normal total number of NK cells in spleen, they showed an impaired recruitment of NK cells to lung and liver. Additionally, lytic NK cells were not efficiently produced from LTα−/− bone marrow cells in vitro in the presence of IL-2 and IL-15. These data suggest that LTα signaling may be involved in the maturation and recruitment of NK cells and may play an important role in antitumor surveillance.

IL-12 is a potent immunoregulatory cytokine that has been shown to mediate tumor regression in a variety of tumor models. We describe the construction of AdCMV-IL-12, a recombinant adenovirus that encodes both subunits of IL-12 under transcriptional control of the CMV promoter. This recombinant virus efficiently infects a wide variety of cell types leading to the production of high levels of biologically active IL-12. Because the liver is a primary site of infection after i.v.-administered adenovirus, we tested the therapeutic efficacy of this virus in a murine hepatic metastasis tumor model. Systemic administration of AdCMV-IL-12 dramatically inhibited the formation of 3-day Renca hepatic metastases (mean of 16 metastases per liver) compared with the control virus AdCMV-βgal (mean of 209) or vehicle alone (mean of 272). Histologic analysis indicated that metastatic growth inhibition was accompanied by a dramatic perivascular infiltrate consisting of T cells, macrophages, and neutrophils. Therapeutic efficacy was not diminished in animals depleted of CD4+ or CD8+ T cells, or in SCID mice, even after NK cell ablation. In the latter case, a hepatic perivascular infiltrate composed of macrophages and neutrophils was observed after AdCMV-IL-12-treatment, while numerous activated Kupffer cells were noted in the hepatic parenchyma. Analysis of therapy-induced changes in hepatic gene expression demonstrated increased levels of IP-10 and Mig RNAs, but no increase in iNOS, Fas, or FasL RNA levels was observed. Our data suggest a model of metastatic growth inhibition mediated by nonlymphocyte effector cells including macrophages and neutrophils and that may involve anti-angiogenic chemokines.

The Microbiota Makes for Good Therapy The gut microbiota has been implicated in the development of some cancers, such as colorectal cancer, but—given the important role our intestinal habitants play in metabolism—they may also modulate the efficacy of certain cancer therapeutics. Iida et al. (p. 967 ) evaluated the impact of the microbiota on the efficacy of an immunotherapy [CpG (the cytosine, guanosine, phosphodiester link) oligonucleotides] and oxaliplatin, a platinum compound used as a chemotherapeutic. Both therapies were reduced in efficacy in tumor-bearing mice that lacked microbiota, with the microbiota important for activating the innate immune response against the tumors. Viaud et al. (p. 971 ) found a similar effect of the microbiota on tumor-bearing mice treated with cyclophosphamide, but in this case it appeared that the microbiota promoted an adaptive immune response against the tumors.

BACKGROUND Interleukin 2 (IL-2) and interleukin 12 (IL-12) are potent immunoregulatory cytokines that exhibit antitumor activity. Preliminary evidence suggests that combined administration of IL-2 and IL-12 may yield greater antitumor activity than that observed with either agent alone. PURPOSE We evaluated the ability of combination regimens of IL-2 and IL-12 to induce regression of established primary and metastatic murine renal carcinoma (Renca) tumors. METHODS BALB/c mice were given either subcutaneous or intrarenal injections of 10(5) Renca cells; tumor cell injections were given to 10-12 mice for each treatment group. Mice bearing subcutaneous primary tumors were treated with chronic IL-2 (300,000 IU given on a daily basis) or pulse IL-2 (300,000 IU given twice daily one day per week) alone, IL-12 alone (0.5 micrograms given on a daily basis), or IL-12 in combination with either chronic or pulse IL-2. Mice with metastatic tumors (arising from intrarenal implants; animals were nephrectomized to remove the primary tumors) were treated with IL-12 plus or minus pulse IL-2; in these experiments, IL-12 was given at doses of either 0.5 or 1.0 micrograms. In most experiments, treatment was continued for at least 3 weeks. Two-sided statistical tests were used to evaluate the data. RESULTS Most mice with subcutaneous Renca tumors treated with the combination of IL-12 and chronic IL-2 died of treatment-related toxic effects within 7-14 days. In contrast, treatment with IL-12 plus pulse IL-2 was well tolerated, and six of 10 mice experienced complete tumor regression; none of the mice treated with either IL-12 alone or pulse Il-2 alone experienced a curative response. Seven of eight and nine of nine mice with metastatic tumors experienced complete tumor regression after treatment with 0.5 micrograms IL-12 plus pulse IL-2 or 1.0 microgram IL-12 plus pulse IL-2, respectively; two of 12 mice treated with pulse IL-2 alone and 10% or less of mice treated with IL-12 alone were cured of metastatic tumors (with 0.5 micrograms IL-12, none of 10 mice; with 1.0 micrograms IL-12, one of 10 mice). Five of 10 mice with metastatic tumors treated with a short-course regimen of IL-12 and pulse IL-2 (two pulses of IL-2 flanking 5 days of 0.5 micrograms IL-12) experienced complete tumor regression, while only one of the 12 mice treated with IL-2 alone and none of the mice treated with IL-12 alone experienced complete tumor regression. Virtually all curative response frequencies obtained with IL-12 and pulse IL-2 combination regimens differed significantly (P < .05) from those obtained with corresponding single-agent treatments. CONCLUSIONS IL-12 administered in combination with pulse IL-2 induced rapid and complete regression of primary and metastatic Renca tumors and displayed greater antitumor activity than that observed with either IL-12 or IL-2 alone.

Treatment of mice bearing orthotopic, metastatic tumors with anti-CD40 antibody resulted in only partial, transient anti-tumor effects whereas combined treatment with IL-2/anti-CD40, induced tumor regression. The mechanisms for these divergent anti-tumor responses were examined by profiling tumor-infiltrating leukocyte subsets and chemokine expression within the tumor microenvironment after immunotherapy. IL-2/anti-CD40, but not anti-CD40 alone, induced significant infiltration of established tumors by NK and CD8 + T cells. To further define the role of chemokines in leukocyte recruitment into tumors, we evaluated anti-tumor responses in mice lacking the chemokine receptor, CCR2. The anti-tumor effects and leukocyte recruitment mediated by anti-CD40 alone, were completely abolished in CCR2 −/− mice. In contrast, IL-2/anti-CD40-mediated leukocyte recruitment and reductions in primary tumors and metastases were maintained in CCR2 −/− mice. Treatment of mice with IL-2/anti-CD40, but not anti-CD40 alone, also caused an IFN-γ-dependent increase in the expression of multiple Th1 chemokines within the tumor microenvironment. Interestingly, although IL-2/anti-CD40 treatment increased Tregs in the spleen, it also caused a coincident IFN-γ-dependent reduction in CD4 + /FoxP3 + Tregs, myeloid-derived suppressor cells and Th2 chemokine expression specifically within the tumor microenvironment that was not observed after treatment with anti-CD40 alone. Similar effects were observed using IL-15 in combination with anti-CD40. Taken together, our data demonstrate that IL-2/anti-CD40, but not anti-CD40 alone, can preferentially reduce the overall immunosuppressive milieu within the tumor microenvironment. These results suggest that the use of anti-CD40 in combination with IL-2 or IL-15 may hold substantially more promise for clinical cancer treatment than anti-CD40 alone.

Innate immune responses provide the host with its first line of defense against infections. Signals generated by subsets of lymphocytes, including NK cells, NKT cells, and APC during this early host response determine the nature of downstream adaptive immune responses. In the present study, we have examined the role of innate NK cells in an autoimmune model through the use of primary immunization with the myelin oligodendrocyte glycoprotein peptide to induce experimental autoimmune encephalomyelitis (EAE). Our studies have shown that in vivo depletion of NK cells can affect the adaptive immune responses, because NK cells were found to regulate the degree of clinical paralysis and to alter immune adaptive responses to the myelin oligodendrocyte glycoprotein peptide. The requirement for NK cells was reflected by changes in the T cell responses and diminished clinical disease seen in mice treated with anti-NK1.1, anti-asialo GM1, and selected Ly49 subtype-depleted mice. In addition to alteration in T cell responses, the maturational status of dendritic cells in lymph nodes was altered both quantitatively and qualitatively. Finally, examination of TCR Vβ usage of the brain lymphocytes from EAE mice indicated a spectra-type change in receptor expression in NK- depleted mice as compared with non-NK-depleted EAE mice. These findings further establish a recently postulated link between NK cells and the generation of autoreactive T cells.

Antiangiogenic gene therapy is a promising strategy for cancer treatment, which generally requires highly efficient delivery systems. To date, success of this strategy has depended almost exclusively on the delivery of high titers of viral vectors, which can result in effective transgene expression. However, their cytotoxicity and immunogenicity are a major concern for clinical applications. Recent advances in delivery efficiency of naked DNA could potentially meet the requirement for both high transgene expression and minimal side effects. To investigate whether naked DNA can be used for antiangiogenic cancer therapy, an expression plasmid was generated that encodes a soluble form of fetal liver kinase-1 (Flk-1) gene, a receptor for vascular endothelial growth factor (VEGF). Hydrodynamic injection of this plasmid resulted in close to 0.1 mg/ml of soluble Flk-1 protein in mouse serum and blocked VEGF-driven angiogenesis in matrigel in vivo. The same delivery significantly suppressed the growth of two different pre-existing subcutaneous tumors, Renca renal cell carcinoma and 3LL lung carcinoma. CD31 immunohistochemistry revealed that the tumor-associated angiogenesis was also highly attenuated in soluble Flk-1-treated mice. Thus, expression of genes by hydrodynamics-based gene delivery of naked DNA appears to be a promising approach for antiangiogenic cancer gene therapy.

Human neuroblastomas possess several mechanisms of self-defense that may confer an ability to resist apoptosis and contribute to the observed difficulty in treating these tumors in the clinical setting. These molecular alterations may include defects in proapoptotic genes as well as the overexpression of prosurvival factors, such as Akt among others. As a key regulator of the turnover of proteins that modulate the cell cycle and mechanisms of apoptosis, the proteasome could serve as an important target for the treatment of neuroblastoma. The present studies provide the first evidence that bortezomib, a newly approved inhibitor of proteasome function, inhibits phosphorylation of Akt, induces the translocation of proapoptotic Bid, and potently enhances the apoptosis of murine neuroblastoma tumor cells in vitro. Furthermore, in that inhibitors of the Akt pathway can sensitize otherwise resistant TBJ/Neuro-2a cells to apoptosis induced by IFN-γ plus TNF-α, we hypothesized that bortezomib also could sensitize these cells to IFN-γ plus TNF-α. We demonstrate for the first time that bortezomib not only up-regulates the expression of receptors for IFN-γ and TNF-α on both TBJ neuroblastoma and EOMA endothelial cell lines, but also markedly enhances the sensitivity of these cells to apoptosis induced by IFN-γ plus TNF-α in vitro. Furthermore, bortezomib enhances the in vivo antitumor efficacy of IFN-γ/TNF-α-inducing cytokines, including both IL-2 and IL-12 in mice bearing well-established primary and/or metastatic TBJ neuroblastoma tumors. Collectively, these studies suggest that bortezomib could be used therapeutically to enhance the proapoptotic and overall antitumor activity of systemic cytokine therapy in children with advanced neuroblastoma.

Neuroblastoma is one of the most common solid tumors in children. The prognosis of patients with advanced neuroblastoma is poor overall despite standard therapeutic modalities and has stimulated substantial interest in the potential role for biologics such as immunotherapeutic and/or antiangiogenic agents for the treatment of neuroblastoma. To facilitate preclinical investigation of the efficacy and mechanisms of action of new biologic agents for the treatment of neuroblastoma, a comprehensive panel of disease-specific fluorescence-based model systems has been developed by our group to image the growth, neovascularization, metastasis, and apoptosis of neuroblastoma tumors. These model systems use fluorescent proteins to monitor cytokine-induced alterations in the growth and metastasis of neuroblastoma and allow for monitoring and/or quantitation of even minimal residual disease that is localized to visceral organ sites such as the liver, lung, and/or bone marrow. Further, based on the differential spectra of red fluorescent protein, green fluorescent protein (GFP), and agents such as 4'-6-diamidino-2-phenylindole (DAPI) (blue) and fluorescein isothiocyanate-dextran (green), multicolor systems have now been established by our group that allow for combined assessment of parameters, including the macroscopic relation of tumors to their associated vasculature and, within tissue sections, simultaneous quantitation of tumor neovascularization and evaluation of therapy-induced apoptosis within the tumor and vascular endothelial compartments. Further, by engineering cells to express specific mediators of apoptosis that have been linked to GFP (ie, BID-EGFP), these systems can also be used to dissect mechanisms by which neuroblastoma cells are induced to undergo apoptosis in vitro as well as in vivo. Collectively, these model systems provide important tools for investigation of the biology of neuroblastoma tumors and evaluation of mechanisms that mediate the regression of these tumors in response to novel therapeutic agents, including cytokines such as interleukin-12.

Background: Patients with advanced neuroblastoma have a poor prognosis. The antiapoptotic protein Akt has been implicated as a possible mediator of the resistance of human neuroblastoma cells to apoptosis; the proapoptotic protein Bid, is inhibited by activated Akt. Neuroblastoma has demonstrated responsiveness to immunotherapeutic approaches in preclinical studies, prompting investigation of new therapeutic strategies based on potentiation of the host immune response, including the use of systemic cytokines. Methods: We examined the antitumor effi cacy and mechanisms of action of the central immunoregulatory cytokine interleukin12 (IL-12) in mice bearing established orthotopic neuroblastoma tumors derived from murine TBJ and Neuro-2a cells. Cohorts of mice (10 mice/group) bearing established orthotopic neuroblastoma tumors were injected intraperitoneally with IL-12 or vehicle and monitored for survival. IL-12 – induced apoptosis within the tumor microenvironment was investigated using ribonuclease protection assays, nuclear staining, and electron microscopy. Protein expression was de termined via Western blot analysis and enzyme-linked immunosorbent assays. Confocal microscopy was used to examine the distribution of overexpressed Bid – enhanced green fl uorescent protein fusion protein (Bid-EGFP) in TBJ cells. All statistical tests were two-sided. Results : IL-12 induced complete tumor regression and long-term survival of 8 (80%) of 10 mice bearing established neuroblastoma tumors compared with 1 (10%) of 10 control mice ( P = .0055) and profound tumor cell apoptosis in vivo despite the fact that TBJ and Neuro-2a cells were resistant to receptor- mediated apoptosis in vitro . These cells expressed high levels of phosphorylated Akt, a key prosurvival molecule, and Akt inhibitors sensitized neuroblastoma cells to apoptosis mediated by IL-12 – inducible cytokines including tumor necrosis factor- α and interferon- γ in vitro. IL-12 increased the expression of proapoptotic genes and decreased Akt phosphorylation within established TBJ tumors in conjunction with activation and subcellular translocation of Bid. Conclusions: Our results suggest that IL-12 overcomes a potentially critical mechanism of tumor self-defense in vivo by inhibiting Akt activity and imply that IL-12 may possess unique therapeutic activity against tumors that express high levels of activated Akt. [J Natl Cancer Inst 2006;98:190 – 202]

We have shown previously that IFN-γ-inducing cytokines such as IL-12 can mediate potent antitumor effects against murine solid tumors. IL-27 is a newly described IL-12-related cytokine that potentiates various aspects of T and/or NK cell function. We hypothesized that IL-27 might also mediate potent antitumor activity in vivo. TBJ neuroblastoma cells engineered to overexpress IL-27 demonstrated markedly delayed growth compared with control mice, and complete durable tumor regression was observed in >90% of mice bearing either s.c. or orthotopic intra-adrenal tumors, and 40% of mice bearing induced metastatic disease. The majority of mice cured of their original TBJ-IL-27 tumors were resistant to tumor rechallenge. Furthermore, TBJ-IL-27 tumors were heavily infiltrated by CD8+ T cells, and draining lymph node-derived lymphocytes from mice bearing s.c. TBJ-IL-27 tumors are primed to proliferate more readily when cultured ex vivo with anti-CD3/anti-CD28 compared with lymphocytes from mice bearing control tumors, and to secrete higher levels of IFN-γ. In addition, marked enhancement of local IFN-γ gene expression and potent up-regulation of cell surface MHC class I expression are noted within TBJ-IL-27 tumors compared with control tumors. Functionally, these alterations occur in conjunction with the generation of tumor-specific CTL reactivity in mice bearing TBJ-IL-27 tumors, and the induction of tumor regression via mechanisms that are critically dependent on CD8+, but not CD4+ T cells or NK cells. Collectively, these studies suggest that IL-27 could be used therapeutically to potentiate the host antitumor immune response in patients with malignancy.

von Hippel-Lindau (VHL) disease is a multisystem inherited cancer syndrome characterized by the development of highly vascular tumors including hemangioblastomas of the retina and central nervous system, pheochromocytomas, and clear cell renal carcinoma, which result from somatic inactivation of the wild-type VHL allele in cells harboring a germ-line VHL mutation. Homozygous inactivation of the VHL gene in mice resulted in embryonic lethality. To produce a mouse model that closely mimics human VHL disease and avoids embryonic lethality, we used Cre/lox site-specific recombination technology. We generated mice carrying conditional VHL alleles and a cre transgene under the control of the human beta-actin promoter, which directs cre expression in a mosaic pattern in multiple organs. VHL(f/d)/Cre mice developed multiple, hepatic hemangiomas that led to premature death, as well as angiectasis and angiogenesis in multiple organs. Interestingly, testes of male VHL(f/d)/Cre mice were unusually small with severely reduced sperm count resulting in infertility. Loss of pVHL function in this VHL conditional knockout mouse model results in an extensive abnormal vascular phenotype in multiple mouse organs, which will provide a useful animal model for testing potential antiangiogenic therapies for VHL disease treatment. Importantly, the phenotypic defects in sperm development observed in these mice support a novel role for VHL in spermatogenesis. This VHL conditional knockout mouse model will provide an in vivo system for studying the functional requirement of the VHL gene in reproductive biology.

In cancer, the coordinate engagement of professional APC and Ag-specific cell-mediated effector cells may be vital for the induction of effective antitumor responses. We speculated that the enhanced differentiation and function of dendritic cells through CD40 engagement combined with IL-2 administration to stimulate T cell expansion would act coordinately to enhance the adaptive immune response against cancer. In mice bearing orthotopic metastatic renal cell carcinoma, only the combination of an agonist Ab to CD40 and IL-2, but neither agent administered alone, induced complete regression of metastatic tumor and specific immunity to subsequent rechallenge in the majority of treated mice. The combination of anti-CD40 and IL-2 resulted in significant increases in dendritic cell and CD8+ T cell number in advanced tumor-bearing mice compared with either agent administered singly. The antitumor effects of anti-CD40 and IL-2 were found to be dependent on CD8+ T cells, IFN-γ, IL-12 p40, and Fas ligand. CD40 stimulation and IL-2 may therefore be of use to promote antitumor responses in advanced metastatic cancer.

Kidney cancer is a devastating disease; however, biological therapies have achieved some limited success. The murine renal cancer Renca has been used as a model for developing new preclinical approaches to the treatment of renal cell carcinoma. Successful cytokine-based approaches require CD8+ T cells, but the exact mechanisms by which T cells mediate therapeutic benefit have not been completely identified. After successful biological therapy of Renca in BALB/c mice, we generated CTLs in vitro using mixed lymphocyte tumor cultures. These CTL mediated tumor-specific H-2Kd-restricted lysis and production of IFN-γ, TNF-α, and Fas ligand (FasL) in response to Renca. CTL used both granule- and FasL-mediated mechanisms to lyse Renca, although granule-mediated killing was the predominant lytic mechanism in vitro. The cytokines IFN-γ and TNF-α increased the sensitivity of Renca cells to CTL lysis by both granule- and FasL-mediated death pathways. Adoptive transfer of these anti-Renca CTL into tumor-bearing mice cured most mice of established experimental pulmonary metastases, and successfully treated mice were immune to tumor rechallenge. Interestingly, we were able to establish Renca-specific CTL from mice gene targeted for perforin (pfp−/−) mice. Although these pfp−/− CTL showed reduced cytotoxic activity against Renca, their IFN-γ production in the presence of Renca targets was equivalent to that of wild-type CTL, and adoptive transfer of pfp−/− CTL was as efficient as wild-type CTL in causing regression of established Renca pulmonary metastases. Therefore, although granule-mediated killing is of paramount importance for CTL-mediated lysis in vitro, some major in vivo effector mechanisms clearly are independent of perforin.

Intrahepatic cholangiocarcinoma (ICC) is the second most common primary liver cancer after hepatocellular carcinoma (HCC). The risk of ICC is higher in patients with primary sclerosing cholangitis (PSC). To date, the cellular and molecular mechanism underlying the pathological progression of PSC and ICC is poorly understood. IKKα is part of the IκB kinase (IKK) complex, which plays an important role in regulating inflammation- associated carcinogenesis through both NF-κB-dependent and independent pathways. Here, we show that IKKα mutant mice developed very serious PSC as early as four weeks of age. The ALT/AST and bilirubin levels were significantly increased in the serum of IKKα mutant mice along with lymphocytic and eosinophilic infiltration into the liver. Liver inflammation in the IKKα mutant mice, mediated by macrophages, neutrophils and CD4+ T cells, was associated with the death of cholangiocytes and hepatocytes, and obstruction of intrahepatic and extrahepatic bile ducts, which impeded bile flow and ultimately led to biliary fibrosis and cirrhosis. Additionally, upon activation of NOTCH signaling in the liver via hydrodynamic shear, we observed that NOTCH-induced ICC, with the PSC, developed significantly faster in IKKα mutant mice. To identify whether intrinsic IKKα dysfunction in hepatocytes promotes the NOTCH-induced ICC in IKKα mutant mice, we generated IKKα hep KO mice, in which IKKα is conditionally knocked out in hepatocytes. No biliary disease or liver injury was observed in these mice. We then established an accelerated ICC model utilizing hydrodynamic delivery of NICD and AKT expression vectors. Unexpectedly, ICC development was remarkably slower in the IKKα hep KO mice compared to the IKKα floxed control mice, and this delayed ICC development was associated with reduced activation or levels of AKT, NOTCH, MAPK/ERK and c-Myc. These data suggest that IKKα may play a protective role in PSC, while promote ICC derived from hepatocytes. In contrast to ICC, we also established the cMET/β-catenin-induced HCC model in the IKKα hep KO mice, which did not reveal any difference in tumor development between IKKα hep KO and control mice. Taken together, our findings suggest that IKKα plays complicated and important roles in PSC and ICC pathological progression. Citation Format: Qun Jiang, Zuoxiang Xiao, Timothy Back, Anthony Scarzello, Scott Roan, Jami Willette-Brown, Feng Zhu, Yinling Hu, Robert H. Wiltrout. Ikkα modulates primary sclerosing cholangitis and intrahepatic cholangiocarcinoma. [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 3618. doi:10.1158/1538-7445.AM2014-3618

IKKα has emerged as a tumor suppressor in squamous cell carcinomas (SCCs) of skin, head and neck, and lung. Our recent studies indicate that inflammation is involved in lung SCCs in kinase-dead knock-in IkkαKA/KA mice. However, how IKKα prevents inflammation has not been fully understood yet. In the present studies, we showed that IkkαKA/KA mice developed reduced thymic medullary regions, systemic inflammation, and severe skin damage, indicating that IKKα plays an essential role linking central tolerance to innate immunity and inflammation. In line with previous studies of the role of NF-κB pathway in thymic medulla formation and the establishment of central tolerance, we found that NF-κB pathway was inactivated in the presence of kinase inactive form of IKKα in thymic epithelial cells. Depleting the lymphocytes, thymus, T cells, macrophages, and/or reintroducing transgenic IKKα into the skin or thymus rescued the severe skin phenotypes. Transferring IkkαKA/KA T cells, but not wild-type T cells, reconstituted the severe skin phenotypes and SCCs in the lungs and forestomach of IkkαKA/KA/Rag-/- mice. We found that the self-reactive T cells provided TGFβ signaling, which enhanced the expression of monocyte chemoattractant protein-1 (MCP-1) in keratinocytes. As a result, increased level of MCP-1 led to robust recruitment of macrophages to the skin, resulting in skin inflammation and hyperproliferation. This study reveals an important IKKα/TGFβ/MCP-1 signaling axis that orchestrates central tolerance and inflammation in the maintenance of tissue homeostasis. Citation Format: Feng Zhu, Zhisong Chen, Jami Willette-Brown, Dakshayani Lomada, Sean R. Davis, Timothy Back, Teizo Yoshimura, Zhonghe Sun, Xiaolin Wu, Robert Wiltrout, Ellen Richie, Ulrich Siebenlist, Giorgio Trichieri, Yinling Hu. IKKα bridges central tolerance to innate immunity and inflammation. [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 4873. doi:10.1158/1538-7445.AM2014-4873

Using a novel transgenic mouse model of spontaneous mammary carcinoma, we show here that the IL-12/pulse IL-2 combination can induce rapid and complete regression of well-established autochthonous tumor in a setting where the host immune system has been conditioned by the full dynamic process of neoplastic progression and tumorigenesis. Further, this regimen inhibits neovascularization of established mammary tumors, and does so in conjunction with potent local induction of genes encoding the IFN-γ- and TNF-α-inducible antiangiogenic chemokines IFN-inducible protein 10 and monokine induced by IFN-γ. In contrast to untreated juvenile C3(1)TAg mice in which histologically normal mammary epithelium predictably undergoes progressive hyperplasia, atypical changes, and ultimately transition to overt carcinoma, the current studies also demonstrate a unique preventative therapeutic role for IL-12/pulse IL-2. In juvenile mice, early administration of IL-12/pulse IL-2 markedly limits the expected genetically programmed neoplastic transition within the mammary epithelium and does so in conjunction with enhancement of constitutive Fas and pronounced induction of local Fas ligand gene expression, T cell infiltration, and induction of apoptosis within the mammary epithelium. These events occur in the absence of a durable Ag-specific memory response. Thus, this novel model system demonstrates that the potent therapeutic activity of the IL-12/pulse IL-2 combination rapidly engages potent apoptotic and antiangiogenic mechanisms that remain active during the delivery of IL-12/pulse IL-2. The results also demonstrate that these mechanisms are active against established tumor as well as developing preneoplastic lesions.

During the last decades lung cancer has become the leading cause of cancer deaths in the world, and the need to develop better diagnostic techniques and therapies is urgent. To advance the understanding of this disease, various genetically engineered and chemical induced mouse models have been established. However, there are no robust animal models of lung squamous cell carcinomas (SCCs), one of the major types of lung cancer. Here, we generated Ikkα-KA/KA knock-in mice (KA/KA) in which an ATP binding site of IKKα, Lys 44 was replaced by alanine. All the knock-in mice at 4 to 6 months of age developed spontaneous lethal lung SCCs associated with markedly increased leukocyte infiltration and expression of cytokines, and chemokines in the lungs. Furthermore, we identified deregulated c-myc, Nanog, Oct3/4, p53, Rb, EGFR, MAPK, Jun-B, p63, Trim29, Rhov, CDK1, and IGF1 in mouse lung SCCs, and identified reduced IKKα and IκBα and increased ROS1 in mutant lungs and SCCs, some of which were found in human lung SCCs. Lung cancers were prevented by reintroducing epithelial-cell IKKα, depleting macrophages or depleting lymphocytes. This study not only provides a novel model for studying the pathogenesis, treatment, early detection, and prevention of human lung SCCs, but also demonstrates how a single mutation in IKKα elicits malignancy through the combined epithelial-cell-autonomous and immune mechanisms. Citation Format: Zuoxiang Xiao, Qun Jiang, Jami Willette-Brown, Feng Zhu, Sichuan Xi, Sandra Burkett, Fanching Lin, Timothy Back, Mahesh Datla, Zhonghe Sun, Romina Goldszmid, Xiaolin Wu, David Schrump, Howard Young, Georgio Trinchieri, Robert Wiltrout, Yinling Hu. The pivotal role of IKKalpha in the development of spontaneous lung squamous cell carcinomas. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 1083. doi:10.1158/1538-7445.AM2013-1083

NF-kB plays critical roles in linking inflammation and carcinogenesis. The activation of NF-kB is regulated by the IkB Kinase Complex (IKK), composed of IKKα, IKKα, and NF-κB essential modulator (NEMO). We have established a mouse model of lung squamous cell carcinoma (SCC) by inactivating IKKα in vivo. However, IKKα's attributes relating to linkage between inflammation and lung SCC have not yet been well-defined. We now show that inactivation of IKKα in mice causes systemic chronic inflammation, which consequently promotes lung SCC initiation and progression. In mice with mutated IKKα, CD4 T cells, dendritic cells, and macrophages are all significantly increased in the spleen and lung. Proinflammatory cytokines and chemokines are also remarkably elevated in the lungs of these mice. An M2 macrophage phenotype is observed only in the lungs of old IKKα mutant mice, not in younger mice, suggesting the M1/M2 polarization may be driven by the proinflammatory microenvironment in these mice. Production of Th2 cytokines and IL-10 are elevated in CD4 T cells from the lungs of mice with mutated IKKα, and may contribute to M2 polarization during the chronic inflammation. In addition, depletion of macrophages in these mice can significantly reduce Th2 cytokine production, oxidative DNA damage, and shut down SCC development in the lungs, suggesting their important roles in inflammation-associated lung carcinogenesis. Together, our data suggest that IKKα may play important roles in linking inflammation and lung SCC tumorigenesis. 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 2561. doi:1538-7445.AM2012-2561

The liver is an immunologically unique organ containing tolerogenic dendritic cells (DC) that maintain an immunosuppressive microenvironment. Although systemic IL-12 administration can improve responses to tumors, the effects of IL-12-based treatments on DC, in particular hepatic DC, remain incompletely understood. In this study, we demonstrate systemic IL-12 administration induces a 2–3 fold increase in conventional, but not plasmacytoid, DC subsets in the liver. Following IL-12 administration, hepatic DC became more phenotypically and functionally mature, resembling the function of splenic DC, but differed as compared to their splenic counterparts in the production of IL-12 following co-stimulation with toll-like receptor (TLR) agonists. Hepatic DCs from IL-12 treated mice acquired enhanced T cell proliferative capabilities similar to levels observed using splenic DCs. Furthermore, IL-12 administration preferentially increased hepatic T cell activation and IFNγ expression in the RENCA mouse model of renal cell carcinoma. Collectively, the data shows systemic IL-12 administration enables hepatic DCs to overcome at least some aspects of the inherently suppressive milieu of the hepatic environment that could have important implications for the design of IL-12-based immunotherapeutic strategies targeting hepatic malignancies and infections.

The antitumor properties of recombinant human IL-7 (rhIL-7) on a human tumor was evaluated by engrafting a human colon carcinoma into immunodeficient mice and then treating the mice with rhIL-7 and adoptively transferred human peripheral blood T cells. It was found that rhIL-7 alone had no effect on the survival of the tumor-bearing recipients. However, the combination of rhIL-7 and human T cells significantly promoted the survival of the recipients compared with mice receiving either treatment by itself. When the surviving mice were analyzed 6 mo later for the degree of human cell engraftment, the recipients receiving both rhIL-7 and human T cells had greater numbers of human CD8+ T cells in the spleens. However, the human T cells recovered from the surviving mice showed low lytic activity against the tumor in vitro. Supernatants from human T cells cultured with the tumor and rhIL-7 in vitro were found to inhibit tumor growth and were demonstrated to contain high levels of IFN-gamma. Antibodies to IFN-gamma neutralized the growth inhibition of the tumor both in vitro and in vivo demonstrating that the in vivo mechanism underlying the antitumor effects of this regimen was partly dependent on the production of IFN-gamma by the T cells and not their cytolytic capability. Interestingly, systemic administration of rhIFN-gamma to tumor-bearing mice yielded little antitumor effect suggesting that adoptive immunotherapy with rhIL-7 was superior possibly because of the continuous local release of the cytokines. Therefore, rhIL-7 may be of clinical use as an antineoplastic agent and the human/mouse model is a potentially important preclinical model for in vivo evaluation of the efficacy of this and other immunotherapies.

mTOR signaling, which plays a central role in controlling cell cell proliferation, survival, mobility and angiogenesis, is considered an important target for new anticancer drugs development. The involvement of the CD40/CD154 signaling pathway has also been reported to play an important role in regulating anti-tumor immune responses. In this study, using a first-in-class orally bioavailable mTOR kinase inhibitor, AZD8055, which, unlike rapamycin, can inhibit both mTORC1 and mTORC2, we evaluated the anti-tumor efficacy of mTOR kinase inhibitor treatment alone in a murine model of metastatic renal cell carcinoma (Renca) and compared biological responses achieved by administering AZD8055 as a single agent to those obtained in combination with agonistic anti-CD40 antibody. In vitro survival assays showed that Renca cell apoptosis could be induced by AZD8055. In vivo, although both agents administered alone had some anti-tumor efficacy, the combination of AZD8055 and CD40 Ab induced a significant anti-tumor response in both intra-renal and intra-splenic inoculations model of renal cell carcinoma, as compared to single agent treatments. The combination treatment, also resulted in an increase and activation of tumor- and liver-associated macrophages, NK cells and CD8 T cells in vivo. AZD8055/anti-CD40 treatment also increased the level of systemic Th1 cytokines, including IL-12, IFN-γ, TNFα. IFN-γ production by CD8+ T cells and TNFα production by macrophages were also found to be elevated in the AZD8055/anti-CD40 combination treated-group, compared with any single treatment group. Furthermore, the expression of Th1-associated chemokines, RANTES and IP10, were significantly induced in the combination treated-group. These data suggest that the combination of mTOR kinase targeting agents with immunotherapy could be an area of further development in renal cancer therapy. 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 5596.