No abstract

PANDER (PANcreatic DERived factor, FAM3B), a newly discovered secreted cytokine, is specifically expressed at high levels in the islets of Langerhans of the endocrine pancreas. To evaluate the role of PANDER in ␤-cell function, we investigated the effects of PANDER on rat, mouse, and human pancreatic islets; the ␤-TC3 cell line; and the ␣-TC cell line. PANDER protein was present in ␣-and ␤-cells of pancreatic islets, insulinsecreting ␤-TC3 cells, and glucagon-secreting ␣-TC cells. PANDER induced islet cell death in rat and human islets. Culture of ␤-TC3 cells with recombinant PANDER had a dose-dependent inhibitory effect on cell viability. This effect was also time-dependent. PANDER caused apoptosis of ␤-cells as assessed by electron microscopy, annexin V fluorescent staining, and flow-cytometric terminal deoxynucleotidyl transferase-mediated dUTP nickend labeling assay. PANDER did not affect cytosolic Ca 2؉ levels or nitric oxide levels. However, PANDER activated caspase-3. Hence, PANDER may have a role in the process of pancreatic ␤-cell apoptosis.

Rapamycin (sirolimus) is a macrolide fungicide with immunosuppressant properties that is used in human islet transplantation. Little is known about the effects of rapamycin on MIN-6 cells and islets. Rapamycin had a dose-dependent, time-dependent, and glucose-independent deleterious effect on MIN-6 cell viability. At day 1, using the MTT method, 0.01 nmol/l rapamycin reduced cell viability to 83 ؎ 6% of control (P < 0.05). Using the calcein AM method, at day 2, 10 nmol/l rapamycin caused a reduction in cell viability to 73 ؎ 5% of control (P < 0.001). Furthermore, 10 and 100 nmol/l rapamycin caused apoptosis in MIN-6 cells as assessed by the transferase-mediated dUTP nick-end labeling assay. Compared with control, there was a 3.1 ؎ 0.6-fold increase (P < 0.01) in apoptosis in MIN-6 cells treated with 10 nmol/l rapamycin. A supra-therapeutic rapamycin concentration of 100 nmol/l significantly impaired glucose-and carbachol-stimulated insulin secretion in rat islets and had a deleterious effect on the viability of rat and human islets, causing apoptosis of both ␣-and ␤-cells.

Osteosarcoma (OS) is the primary bone tumor in children and young adults. Currently, there are no reliable, noninvasive biologic markers to detect the presence or progression of disease, assess therapy response, or provide upfront prognostic insights. MicroRNAs (miRNAs) are evolutionarily conserved, stable, small noncoding RNA molecules that are key posttranscriptional regulators and are ideal candidates for circulating biomarker development due to their stability in plasma, ease of isolation, and the unique expressions associated with specific disease states. Using a qPCR-based platform that analyzes more than 750 miRNAs, we analyzed control and diseased-associated plasma from a genetically engineered mouse model of OS to identify a profile of four plasma miRNAs. Subsequent analysis of 40 human patient samples corroborated these results. We also identified disease-specific endogenous reference plasma miRNAs for mouse and human studies. Specifically, we observed plasma miR-205-5p was decreased 2.68-fold in mice with OS compared to control mice, whereas, miR-214, and miR-335-5p were increased 2.37- and 2.69-fold, respectively. In human samples, the same profile was seen with miR-205-5p decreased 1.75-fold in patients with OS, whereas miR-574-3p, miR-214, and miR-335-5p were increased 3.16-, 8.31- and 2.52-fold, respectively, compared to healthy controls. Furthermore, low plasma levels of miR-214 in metastatic patients at time of diagnosis conveyed a significantly better overall survival. This is the first study to identify plasma miRNAs that could be used to prospectively identify disease, potentially monitor therapeutic efficacy and have prognostic implications for OS patients.

The outcome of patients with metastatic osteosarcoma has not improved since the introduction of chemotherapy in the 1970s. Development of therapies targeting the metastatic cascade is a tremendous unmet medical need. The Wnt signaling pathway has been the focus of intense investigation in osteosarcoma because of its role in normal bone development. Although the role of Wnt signaling in the pathogenesis of osteosarcoma is controversial, there are several reports of dickkopf-1 (DKK-1), a Wnt signaling antagonist, possibly playing a pro-tumorigenic role. In this work we investigated the effect of anti-DKK-1 antibodies on the growth and metastasis of patient-derived osteosarcoma xenografts. We were able to detect human DKK-1 in the blood of tumor-bearing mice and found a correlation between DKK-1 level and tumor proliferation. Treatment with the anti-DKK-1 antibody, BHQ880, slowed the growth of orthotopically implanted patient-derived osteosarcoma xenografts and inhibited metastasis. This effect was correlated with increased nuclear beta-catenin staining and increased expression of the bone differentiation marker osteopontin. These findings suggest that Wnt signaling is anti-tumorigenic in osteosarcoma, and support the targeting of DKK-1 as an anti-metastatic strategy for patients with osteosarcoma.

Patients and families affected by sarcomas often ask, "What is cancer?" Answers frequently portray cancer as mutant cells gone rogue with rapid, uncontrolled, and even zombie-like growth. This analogy may be helpful for encouraging compliance during chemotherapy, when cure requires enduring significant toxicity. However, this "zombie" paradigm understates cancer's most lethal and sophisticated property-its ability to evolve. [1][2][3][4] In contrast, viewing cancer as an invasive and evolving species may provide a more accurate and accessible analogy. This model "normalizes" cancer cells by emphasizing their obedience to the same laws of ecology and evolution that govern all living systems. Within this framework, the Darwinian dynamics of evolution can be leveraged to improve understanding of tumor growth and resistance.Normal mammalian cells do not evolve because their fates are determined by collective tissue controls, making their fitness (for a Glossary of Terms, see Table 1) identical to that of the host organism. Fundamentally, cancer is a shift in the order of natural selection from the host level to that of an individual cancer cell. This new, "self-defined" fitness function of the cancer cell can be considered a speciation event. 3 In becoming a singular unit of natural selection, a cancer cell must respond to external influences from the host environment. To understand malignancy as a complex, adapting system of cancer cells, we introduce key terms and emerging theories from evolutionary biology that may translate into novel clinical trials. Although evolutionary principles are applicable to many cancer types across adult and pediatric oncology, here, we apply these concepts to pediatric sarcoma, using an evolution-inspired clinical trial in metastatic fusion-positive rhabdomyosarcoma (FPRMS) as an illustration. PEDIATRIC SARCOMASSarcomas, such as osteosarcoma, Ewing sarcoma, and rhabdomyosarcoma, collectively make up 10% of malignancies in children and young adults. Even when disease is clinically localized at presentation, surgery and/or radiation alone is usually insufficient for cure, as a majority of patients will relapse, frequently through development of distant metastases. Because there are no current ways to identify patients who can be cured by local control alone, chemotherapy is recommended for all patients. Cure rates increase up to 65% to 80% for localized disease with the addition of combination chemotherapy. [5][6][7][8][9] Although there is a growing understanding of the genetic features distinguishing sarcoma cells from somatic cells, the most successful treatments target pathways common to tumor and normal cells alike, so-called "never mutated pathways," such as DNA synthesis and replication, topoisomerase-mediated DNA repair, and microtubule function. 2,10-15 Unfortunately, outcomes for metastatic pediatric sarcomas have changed little over the past 2 decades, and the prognosis for metastatic pediatric sarcomas remains dismal. [16][17][18] The application of evolutionary concepts to ...

There are few effective therapies for high-risk sarcomas. Initial chemosensitivity is often followed by relapse. In vitro, mTOR inhibition potentiates the efficacy of chemotherapy on resistant sarcoma cells. Although sarcoma trials using mTOR inhibitors have been disappointing, these drugs were used as maintenance. We conducted a Phase I/II clinical trial to test the ability of temsirolimus to potentiate the cytotoxic effect of liposomal doxorubicin and present here the dose-finding portion of this study. Adult and pediatrics patients with recurrent or refractory sarcomas were treated with increasing doses of liposomal doxorubicin and temsirolimus using a continual reassessment method for escalation, targeting a dose-limiting toxicity rate of 20%. Blood samples were drawn before and after the first dose of temsirolimus in Cycles 1 and 2 for pharmacokinetic analysis. The maximally tolerated dose combination was liposomal doxorubicin 30 mg/m2 monthly with temsirolimus 20 mg/m2 weekly. Hematologic toxicity was common but manageable. Dose-limiting toxicities were primarily renal. Concurrent administration of liposomal doxorubicin resulted in increased exposure to sirolimus, the active metabolite of temsirolimus. Thus, the combination of liposomal doxorubicin and temsirolimus is safe for heavily pretreated sarcoma patients. Coadministration with liposomal doxorubicin did not alter temsirolimus pharmacokinetics, but increased exposure to its active metabolite.

The VXLD with metformin was tolerable with a RP2D for metformin of 1,000 mg/m /day and yielded responses in a heavily pretreated population. ER stress was induced and toxicities attributable to metformin occurred in all dose levels.