Essential roles of Jab1 in cell survival, spontaneous DNA damage and DNA repair

Jun activation domain-binding protein 1 (JAB1) is a multifunctional protein that participates in the control of cell proliferation and the stability of multiple proteins. JAB1 overexpression has been implicated in the pathogenesis of human cancer. JAB1 regulates several key proteins and thereby produces varied effects on cell cycle progression, genome stability and cell survival. However, the biological significance of JAB1 activity in these cellular signaling pathways is unclear. Therefore, we developed mice that were deficient in Jab1 and analyzed the null embryos and heterozygous cells. This disruption of Jab1 in mice resulted in early embryonic lethality due to accelerated apoptosis. Loss of Jab1 expression sensitized both mouse primary embryonic fibroblasts and osteosarcoma cells to γ-radiation-induced apoptosis, with an increase in spontaneous DNA damage and homologous recombination (HR) defects, both of which correlated with reduced levels of the DNA repair protein Rad51 and elevated levels of p53. Furthermore, the accumulated p53 directly binds to Rad51 promoter, inhibits its activity and represents a major mechanism underlying the HR repair defect in Jab1-deficient cells. These results indicate that Jab1 is essential for efficient DNA repair and mechanistically link Jab1 to the maintenance of genome integrity and to cell survival.

Detection of lung, breast, colorectal, and prostate cancers from exhaled breath using a single array of nanosensors

Background:

Tumour growth is accompanied by gene and/or protein changes that may lead to peroxidation of the cell membrane species and, hence, to the emission of volatile organic compounds (VOCs). In this study, we investigated the ability of a nanosensor array to discriminate between breath VOCs that characterise healthy states and the most widespread cancer states in the developed world: lung, breast, colorectal, and prostate cancers.

Methods:

Exhaled alveolar breath was collected from 177 volunteers aged 20–75 years (patients with lung, colon, breast, and prostate cancers and healthy controls). Breath from cancerous subjects was collected before any treatment. The healthy population was healthy according to subjective patient's data. The breath of volunteers was examined by a tailor-made array of cross-reactive nanosensors based on organically functionalised gold nanoparticles and gas chromatography linked to the mass spectrometry technique (GC-MS).

Results:

The results showed that the nanosensor array could differentiate between ‘healthy’ and ‘cancerous’ breath, and, furthermore, between the breath of patients having different cancer types. Moreover, the nanosensor array could distinguish between the breath patterns of different cancers in the same statistical analysis, irrespective of age, gender, lifestyle, and other confounding factors. The GC-MS results showed that each cancer could have a unique pattern of VOCs, when compared with healthy states, but not when compared with other cancer types.

Conclusions:

The reported results could lead to the development of an inexpensive, easy-to-use, portable, non-invasive tool that overcomes many of the deficiencies associated with the currently available diagnostic methods for cancer.

Abstract 57: Inhibition of human melanoma proliferation by combination treatment with ODC inhibitor and mTOR inhibitor

Recent reports have demonstrated that polyamine synthesis is critical for tumor cell growth. Furthermore, mTOR was also shown to be critical for tumor cell growth. We hypothesized that inhibition of key polyamine synthesis enzyme, ornithine decarboxylase (ODC), and mTOR would have growth inhibitory effect on human melanoma cells.

ODC expression was evaluated in human melanoma and human melanoma cell lines by Western blot using polyclonal goat anti-ODC and quantitative real-time PCR using TaqMan Gene Expression Assay Applied Biosystems). The siRNA duplexes targeting ODC and a scrambled control siRNA were designed and synthesized (Santa Cruz, CA) and transient transfections were performed. Cell proliferation assay was performed using Cell Titer Blue cell proliferation assay according to the manufacturer's protocol. The cells were treated with or without various concentrations of DFMO or rapamycin or combination then incubated up to 96 hours. For comparison between groups, the Student's t test were used and p<0.05 was considered to be statistically significant.

Over-expression of ODC was observed in human melanoma cells compared with tumor asssociated fibroblasts as well as human melanoma cells. Over-expression of ODC was observed in six of the ten human melanoma cell lines on Western blot analysis and RT-PCR analysis. Dose-dependent growth inhibition of human melanoma cells were observed following DFMO treatment (p<0.05) in melanoma cell lines with over expression of ODC and correlated with suppression of ODC expression levels. Grow inhibition was also observed folllowing Rapamycin treatment in the melanoma cell lines. Treatment with ODC-siRNA also resulted in significant growth inhibition of melanoma cell lines. Effects of DFMO induced growth inhibition of melanoma cells were further enhanced with combined treatment with rapamycin.

Overexpression of ODC was observed in human melanoma cells. Inhibition of polyamine synthesis and mTOR can have significant growth inhibitory effects on human melanoma.

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 57.

Tumor microenvironments direct the recruitment and expansion of human Th17 cells (100.28)

Although Th17 cells play critical roles in the pathogenesis of many inflammatory and autoimmune diseases, their prevalence among tumor-infiltrating lymphocytes (TILs) and function in human tumor immunity remains largely unknown. We have recently demonstrated high percentages of Th17 cells in TILs from ovarian cancer patients, but the mechanisms of accumulation of these Th17 cells in the tumor microenvironment are still unclear. In this study, we further showed elevated Th17 cell populations in the TILs obtained from melanoma, breast and colon cancers, suggesting that development of tumor-infiltrating CD4+ Th17 cells may be a general feature in cancer patients. We then demonstrated that tumor microenvironmental RANTES and MCP-1 secreted by tumor cells and tumor-derived fibroblasts mediate the recruitment of Th17 cells. In addition, we found that tumor cells and tumor-derived fibroblasts produce a proinflammatory cytokine milieu as well as provide cell-to-cell contact engagement that facilitates the generation and expansion of Th17 cells. We also showed that inflammatory TLR and NOD2 signaling promote the attraction and generation of Th17 cells induced by tumor cells and tumor-derived fibroblasts. These results identify Th17 cells as an important component of human TILs, demonstrate mechanisms involved in the recruitment and regulation of Th17 cells in tumor microenvironments, and provide new insights relevant for the development of novel cancer immunotherapeutic approaches.

Characterization of regulatory T cells in tumor suppressive microenvironments

Increasing evidence suggests that immunotherapy is a promising strategy for treating patients with invasive and metastatic cancers, but clinical trails are discouraging so far. Recent studies showed that several subsets of regulatory tumor-infiltrating lymphocytes (TILs), such as naturally occurring CD4(+)CD25(+) regulatory T cells (Treg), and adaptively induced Treg cells of Tr1, Th3, CD8(+), as well as gammadelta Treg cells, have been identified in human cancers. These Treg-cell subsets form a tumor suppressive microenvironment that presents a major barrier to successful anti-tumor immunotherapy. Thus, how to modulate the Treg-cell function in tumor microenvironments is essential for cancer treatment and elimination. To date, there is no unique and selective marker for all subsets of Treg cells, and a combination of assays for Treg-associated markers and suppressive activity is still the most common way used to define these tumor-associated Treg cells. In this chapter, we describe protocols to purify and characterize tumor-associated Treg cells from peripheral blood and TILs of cancer patients, which is critical for predicting clinical outcomes and monitoring the effects of tumor immunotherapy.

The structure of eukaryotic and prokaryotic complex I

The structures of the NADH dehydrogenases from Bos taurus and Aquifex aeolicus have been determined by 3D electron microscopy, and have been analyzed in comparison with the previously determined structure of Complex I from Yarrowia lipolytica. The results show a clearly preserved domain structure in the peripheral arm of complex I, which is similar in the bacterial and eukaryotic complex. The membrane arms of both eukaryotic complexes show a similar shape but also significant differences in distinctive domains. One of the major protuberances observed in Y. lipolytica complex I appears missing in the bovine complex, while a protuberance not found in Y. lipolytica connects in bovine complex I a domain of the peripheral arm to the membrane arm. The structural similarities of the peripheral arm agree with the common functional principle of all complex Is. The differences seen in the membrane arm may indicate differences in the regulatory mechanism of the enzyme in different species.

Tumor microenvironments direct the recruitment and expansion of human Th17 cells

Although Th17 cells play critical roles in the pathogenesis of many inflammatory and autoimmune diseases, their prevalence among tumor-infiltrating lymphocytes (TILs) and function in human tumor immunity remains largely unknown. We have recently demonstrated high percentages of Th17 cells in TILs from ovarian cancer patients, but the mechanisms of accumulation of these Th17 cells in the tumor microenvironment are still unclear. In this study, we further showed elevated Th17 cell populations in the TILs obtained from melanoma and breast and colon cancers, suggesting that development of tumor-infiltrating CD4(+) Th17 cells may be a general feature in cancer patients. We then demonstrated that tumor microenvironmental RANTES and MCP-1 secreted by tumor cells and tumor-derived fibroblasts mediate the recruitment of Th17 cells. In addition to their recruitment, we found that tumor cells and tumor-derived fibroblasts produce a proinflammatory cytokine milieu as well as provide cell-cell contact engagement that facilitates the generation and expansion of Th17 cells. We also showed that inflammatory TLR and nucleotide oligomerization binding domain 2 signaling promote the attraction and generation of Th17 cells induced by tumor cells and tumor-derived fibroblasts. These results identify Th17 cells as an important component of human TILs, demonstrate mechanisms involved in the recruitment and regulation of Th17 cells in tumor microenvironments, and provide new insights relevant for the development of novel cancer immunotherapeutic approaches.

Evaluation of the safety and pharmacokinetics of the multi-targeted receptor tyrosine kinase inhibitor sunitinib during embryo-fetal development in rats and rabbits

BACKGROUND

Angiogenesis plays a key role in embryo-fetal development and, based on nonclinical safety data, the majority of vascular endothelial growth factor (VEGF)-targeted antiangiogenic agents used in cancer therapy are not recommended during pregnancy. We investigated the effects of sunitinib (an oral inhibitor of multiple receptor tyrosine kinases [RTKs] including VEGF-receptors) on embryo-fetal development.

METHODS

Presumed-pregnant Sprague-Dawley rats and New Zealand White rabbits received repeated daily oral doses of sunitinib (0-30 mg/kg/day), during the major period of organogenesis. Clinical/physical examinations were performed throughout the gestation phase, and blood samples were collected to determine systemic exposure. Necropsy (including uterine examination) was performed on all animals and fetal morphology was examined.

RESULTS

The no-observed-adverse-effect level was 1-5 mg/kg/day for maternal toxicity and 3 mg/kg/day for developmental toxicity in rats; 1 and 0.5 mg/kg/day, respectively, in rabbits. Embryo-fetal toxicity included decreases in the number of live fetuses and increases in the numbers of resorptions and post-implantation/complete litter losses; these were observed at doses of > or =5 mg/kg/day in rats and 5 mg/kg/day in rabbits. Malformations included fetal skeletal malformations (generally thoracic/lumbar vertebral alterations) in rats and cleft lip/palate in rabbits. These developmental effects were observed at approximately 5.5- (rats) and approximately 0.3-times (rabbits) the human systemic exposure at the approved sunitinib dose (50 mg/day).

CONCLUSIONS

Similar effects have been reported with the prototype monoclonal antibody bevacizumab. As is typically observed for potent inhibitors of RTKs involved in angiogenesis, sunitinib was associated with embryo-fetal developmental toxicity in rats and rabbits at clinically relevant dose levels.

A phase I study of pemetrexed plus carboplatin or cisplatin with concurrent chest radiation therapy (CRT) for patients with locally advanced non-small cell lung cancer (LANSCLC)

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Background: Pemetrexed is a multi-targeted antifolate that inhibits the synthesis of both pyrimidines and purines. Pemetrexed is an effective new chemotherapeutic agent in advanced non-small cell lung cancer. Pemetrexed has also shown preclinical activity as a radiosensitizer in lung cancer. A phase I study was performed to establish the maximum tolerated dose (MTD) and phase 2 dose of carboplatin or cisplatin given with pemetrexed and CRT in LANSCLC. Methods: Patients (pts) with LANSCLC were enrolled. Initial intent was to establish the MTD of both weekly cisplatin and weekly carboplatin in combination with pemetrexed and CRT as an alternating two-arm phase I trial. Subsequently and based on early results from the CALGB 30407 trial (also evaluating the MTD of carboplatin), the protocol was amended to establish the safety of the planned phase II doses of cisplatin and carboplatin combined with pemetrexed 500 mg/m2 and given every 3 weeks with concurrent CRT. Dose limiting toxicity (DLT) was defined as ≥ Grade 3 hematologic or nonhematologic toxicity based on Common Terminology Criteria for Adverse Events (CTCAE) version 3.0. MTD was determined by occurrence of 2 DLTs among 6 pts in each cohort. Results: 22 pts were enrolled on 3 cohorts. All pts received pemetrexed, 9 with carboplatin AUC=2, 9 with cisplatin 30 mg/m2, and 4 with cisplatin 75 mg/m2. One DLT occurred in each of the carboplatin and cisplatin 30 mg/m2 cohorts, prompting enrollment of 3 additional patients. No DLTs were seen in the cisplatin 75 mg/m2 cohort. Conclusions: The MTD of cisplatin in combination with pemetrexed and CRT was not reached. Based on these results and those from CALGB 30407, either carboplatin AUC=5 or cisplatin 75 mg/m2 in combination with pemetrexed 500 mg/m2 given every 3 weeks with CRT appears to be well tolerated, and are currently being studied in a randomized phase II trial in pts with LANSCLC.

[Table: see text]

Sniffing out cancer from real breath samples by means of nanomaterial-based electronic nose device

e17552

Background: Several studies have shown that characteristic patterns of volatile organic compounds (VOCs) appear to be elevated in the alveolar breath of cancer patients, as compared to healthy controls. It has been shown, that VOCs’ composition acts as a fingerprint for the distinction of a certain cancer from other cancers, including the cases where various cancers have similar type of biomarkers. The goal of the current study is to establish a background to ultimately achieve a simple-to-use device that can detect such patterns of cancer when exhaling into it. Methods: Breath samples were collected from 40 healthy volunteers and 75 patients having known conditions in six main categories: (I) 40 healthy controls; (II) 30 patients with lung cancer; (III) 15 patients with breast cancer; (IV) 20 patients with colon cancer; (V) 5 patients with prostate cancer; and (VI) 5 patients with head and neck cancer. The breath of the volunteers was examined by means of gas chromatography linked with mass spectrometry technique (GC-MS) as well as by an electronic nose device that is based on molecularly modified Au nanoparticles to check the feasibility of the electronic nose in cancer detection via breath samples Results: GC-MS results showed that each category of cancer has a unique pattern (or mixture) of VOCs. In parallel to these findings, results indicate the ability of nanomaterial-based electronic nose devices to differentiate between “healthy” and “cancerous” breath, and, furthermore, between the breath of patients with different cancer types, with >92% sensitivity. Conclusions: The electronic nose technology has a high potential for assessing various types of cancer via simple exhalation procedure. The results provide a launching pad towards obtaining an inexpensive, compact tool that is amenable to widespread screening and that has a potential for direct and real-time monitoring (2–3 minutes only).

No significant financial relationships to disclose.

Tumor-associated galectin-3 modulates the function of tumor-reactive T cells

T cells play an important role in cancer immunosurveillance and tumor destruction. However, tumor cells alter immune responses by modulating immune cells through antigen stimulation and immunoregulatory cytokines. A better understanding of the interplay between tumor cells and T cells might provide new strategies to enhance antitumor immunity. Through an antigen-screening approach using colorectal tumor-reactive T cells, we identified an HLA-DR11-restricted T-cell epitope encoded by KIAA0040 as well as MHC-unrestricted human galectin-3 (Gal-3) expressed by tumor cells. Although the biological function of KIAA0040 remains to be determined, we found that Gal-3 functioned as an immune regulator for direct T-cell activation and function. T-cell activation induced by Gal-3 resulted in T-cell apoptosis. We showed that a high level of expression of Gal-3 promoted tumor growth in vitro and in vivo. Using a mouse tumor model, we showed that delivery of high doses of Gal-3 inhibited tumor-reactive T cells and promoted tumor growth in mice receiving tumor-reactive CD8(+) T cells. These findings suggest that Gal-3 may function as an immune regulator to inhibit T-cell immune responses and promote tumor growth, thus providing a new mechanism for tumor immune tolerance.

Salacia oblonga root decreases cardiac hypertrophy in Zucker diabetic fatty rats: inhibition of cardiac expression of angiotensin II type 1 receptor

AIMS

We investigated the effect of the water extract of Salacia oblonga (SOE), an ayurvedic antidiabetic and antiobesity medicine, on obesity and diabetes-associated cardiac hypertrophy and discuss the role of modulation of cardiac angiotensin II type 1 receptor (AT(1)) expression in the effect.

METHODS

SOE (100 mg/kg) was given orally to male Zucker diabetic fatty (ZDF) rats for 7 weeks. At the end-point of the treatment, the hearts and left ventricles were weighed, cardiomyocyte cross-sectional areas were measured, and cardiac gene profiles were analysed. On the other hand, angiotensin II-stimulated embryonic rat heart-derived H9c2 cells and neonatal rat cardiac fibroblasts were pretreated with SOE and one of its prominent components mangiferin (MA), respectively. Atrial natriuretic peptide (ANP) mRNA expression and protein synthesis and [(3)H]thymidine incorporation were determined.

RESULTS

SOE-treated ZDF rats showed less cardiac hypertrophy (decrease in weights of the hearts and left ventricles and reduced cardiomyocyte cross-sectional areas). SOE treatment suppressed cardiac overexpression of ANP, brain natriuretic peptide (BNP) and AT(1) mRNAs and AT(1) protein in ZDF rats. SOE (50-100 microg/ml) and MA (25 micromol) suppressed angiotensin II-induced ANP mRNA overexpression and protein synthesis in H9c2 cells. They also inhibited angiotensin II-stimulated [(3)H]thymidine incorporation by cardiac fibroblasts.

CONCLUSIONS

Our findings demonstrate that SOE decreases cardiac hypertrophy in ZDF rats, at least in part by inhibiting cardiac AT(1) overexpression. These studies provide insights into a potential cardioprotective role of a traditional herb, which supports further clinical evaluation in obesity and diabetes-associated cardiac hypertrophy.

CD8+ Foxp3+ regulatory T cells mediate immunosuppression in prostate cancer

PURPOSE

Although elevated proportions of CD4(+)CD25(+) regulatory T (Treg) cells have been shown in several types of cancers, very little is known about the existence and function of CD8(+) Treg cells in prostate cancer. In this study, we investigated prostate tumor-derived CD8(+) Treg cells and their function.

EXPERIMENTAL DESIGN

Tumor-infiltrating lymphocytes (TIL) from fresh tumor specimens of patients with prostate cancer were generated and subjected to phenotypic and suppressive function analyses. In particular, we investigated the role and function CD8(+) Treg cells in prostate cancer.

RESULTS

We show that high percentages of CD4(+)CD25(+) T cells are probably present in the majority (70%) of prostate TILs. Remarkably, both CD4(+) and CD8(+) T-cell subpopulations possessed potent suppressive activity. T-cell cloning and fluorescence-activated cell sorting analyses showed the presence of CD8(+)CD25(+) Treg cell clones that expressed FoxP3 and suppressed naïve T-cell proliferation, in addition to the previously known CD4(+)CD25(+) Treg cells. These CD8(+) Treg cells suppressed naïve T-cell proliferation mainly through a cell contact-dependent mechanism. Importantly, the suppressive function of CD8(+) Treg cells could be reversed by human Toll-like receptor 8 (TLR8) signaling.

CONCLUSION

Our study shows that like CD4(+)CD25(+) Treg cells, CD8(+) Foxp3(+) Treg cells present in prostate tumor-derived TILs suppress immune responses and that their suppressive function can be regulated by TLR8 ligands, raising the possibility that the manipulation of Treg cell function by TLR8 ligands could improve the efficacy of immunotherapy for prostate cancer patients.

Engineering human tumor-specific cytotoxic T cells to function in a hypoxic environment

Hypoxia occurs in many tumors and reduces the effectiveness of radio- and chemotherapy. Hypoxia also impedes immune responses to tumors, reducing T lymphocyte production of cytokines such as interleukin-2 (IL-2) and interferon gamma, as well as the survival and proliferation of these cells. We constructed a lentiviral vector encoding a bidirectional hypoxia-inducible responsive element (HRE) derived from human vascular endothelial growth factor, which drives the hIL-2 gene and a marker gene. We used a model of human B cell lymphoma to show that tumor-specific T cells modified with this vector upregulate hIL-2 expression when oxygen tension is low in vitro and in vivo. The consequence of this effect is to increase T-cell survival and proliferation whilst sustaining effector function, even in O(2) concentrations as low as 1%. The phenotype of the transduced cells is unchanged, as is their ability to migrate to tumor. HRE-IL-2-modified cytotoxic T lymphocytes (CTLs) produce faster and more complete tumor regression than parental CTLs and increase overall survival. Hypoxia-resistant T cells may thus be of value in the treatment of human tumors in which areas of hypoxia may otherwise account for resistance to this therapeutic strategy.

Tumor-infiltrating gammadelta T cells suppress T and dendritic cell function via mechanisms controlled by a unique toll-like receptor signaling pathway

gammadelta T cells are important contributors to innate immunity against cancer, but their regulatory role in controlling immune responses remains largely unknown. Here we report that a dominant gammadelta1 T cell population among lymphocytes infiltrating breast tumors possessed a potent ability to suppress naive and effector T cell responses and to block the maturation and function of dendritic cells. Adoptive cotransfer experiments demonstrated their in vivo suppressive activity. However, their immunosuppressive activity could be reversed by human Toll-like receptor (TLR) 8 ligands both in vitro and in vivo. siRNA-mediated knockdown experiments revealed that MyD88, TRAF6, IKKalpha IKKbeta, and p38alpha molecules in gammadelta1 cells were required for these cells to respond to TLR8 ligands, whereas TAK1, JNK, and ERK molecules did not appear to be involved in functional regulation. These results provide new insights into the regulatory mechanisms of tumor-specific gammadelta T cells and identify a unique TLR8 signaling pathway linking to their functional regulation.