Biologic and clinical characteristics of adolescent and young adult cancers: Acute lymphoblastic leukemia, colorectal cancer, breast cancer, melanoma, and sarcoma.

Adolescent and young adult (AYA) patients with cancer have not attained the same improvements in overall survival as either younger children or older adults. One possible reason for this disparity may be that the AYA cancers exhibit unique biologic characteristics, resulting in differences in clinical and treatment resistance behaviors. This report from the biologic component of the jointly sponsored National Cancer Institute and LiveStrong Foundation workshop entitled "Next Steps in Adolescent and Young Adult Oncology" summarizes the current status of biologic and translational research progress for 5 AYA cancers; colorectal cancer breast cancer, acute lymphoblastic leukemia, melanoma, and sarcoma. Conclusions from this meeting included the need for basic biologic, genomic, and model development for AYA cancers as well as translational research studies to elucidate any fundamental differences between pediatric, AYA, and adult cancers. The biologic questions for future research are whether there are mutational or signaling pathway differences (for example, between adult and AYA colorectal cancer) that can be clinically exploited to develop novel therapies for treating AYA cancers and to develop companion diagnostics.

ERF, an ETS-related transcriptional repressor, can induce erythroid differentiation.

Ets-family genes have been implicated in leukemia, as well as in normal hematopoiesis. ERF is an ets-related gene that represses transcription and is regulated by MAPK phosphorylation through its effect on ERF sub-cellular localization. Using pluripotent human cell lines, we studied the effect of ERF on erythroid differentiation. K562 and HEL cells expressing ERF expressed elevated levels of the erythroid-specific markers CD71 and Glycophorin A, as well as hemoglobin and GATA1. Treatment with the Erk kinase inhibitor PD98058 further enhanced the erythroid phenotype in ERF-expressing cells and cells expressing a non-phosphorylatable ERF mutant exhibited an even more enhanced phenotype. These results are consistent with the fact that ERF function is regulated by MAPK, and suggest that the effect of the MAPK pathway in erythroid differentiation is partially mediated by ERF. The effect of ERF is similar to the one shown for ETS1 and opposite to the FLI1 function in these cells, suggesting that several ets genes may play key roles in hematopoietic differentiation.

Unique characteristics of adolescent and young adult acute lymphoblastic leukemia, breast cancer, and colon cancer.

Each year in the United States, nearly 70 000 individuals between the ages of 15 and 40 years are diagnosed with cancer. Although overall cancer survival rates among pediatric and older adult patients have increased in recent decades, there has been little improvement in survival of adolescent and young adult (AYA) cancer patients since 1975 when collected data became adequate to evaluate this issue. In 2006, the AYA Oncology Progress Review Group made recommendations for addressing the needs of this population that were later implemented by the LIVESTRONG Young Adult Alliance. One of their overriding questions was whether the cancers seen in AYA patients were biologically different than the same cancers in adult and/or pediatric patients. On June 9-10, 2009, the National Cancer Institute (NCI) and the Lance Armstrong Foundation (LAF) convened a workshop in Bethesda, MD, entitled "Unique Characteristics of AYA Cancers: Focus on Acute Lymphocytic Leukemia (ALL), Breast Cancer and Colon Cancer" that aimed to examine the current state of basic and translational research on these cancers and to discuss the next steps to improve their prognosis and treatment.

Oncogenicity of DNA in vivo: tumor induction with expression plasmids for activated H-ras and c-myc.

All vaccines and other biological products contain contaminating residual DNA derived from the production cell substrate. Whether this residual cell-substrate DNA can induce tumors in vaccine recipients and thus represent a risk factor has been debated for over 50 years without resolution. As a first step in resolving this issue, we have generated expression plasmids for the activated human H-ras oncogene and for the murine c-myc proto-oncogene. Their oncogenic activity was confirmed in vitro using the focus-formation transformation assay. Two strains of adult and newborn immune-competent mice were inoculated with different amounts of either plasmid alone or with a combination of the H-ras and c-myc plasmids. Tumors developed only in mice inoculated with both plasmids and only at the highest amount of DNA (12.5 microg of each plasmid). The NIH Swiss mouse was more sensitive than the C57BL/6 mouse, and newborn animals were more sensitive than adults. Cell lines were established from the tumors. PCR and Southern hybridization analyses demonstrated that both inoculated oncogenes were present in all of the tumor-derived cell lines and that the cells in the tumors were clonal. Western analysis demonstrated that both oncoproteins were expressed in these cell lines. These results demonstrate that cellular oncogenes can induce tumors following subcutaneous inoculation. Such information provides a possible way of evaluating and estimating the theoretical oncogenic risk posed by residual cell-substrate DNA in vaccines.

Drm/Gremlin transcriptionally activates p21(Cip1) via a novel mechanism and inhibits neoplastic transformation.

Drm/Gremlin, a member of the Dan family of BMP antagonists, is known to function in early embryonic development, but is also expressed in a tissue-specific fashion in adults and is significantly downregulated in transformed cells. In this report, we demonstrate that overexpression of Drm in the tumor-derived cell lines Daoy (primitive neuroectodermal) and Saos-2 (osteoblastic), either under ecdysone-inducible or constitutive promoters, significantly inhibits tumorigenesis. Furthermore, Drm overexpression in these cells increases the level of p21(Cip1) protein and reduces the level of phosphorylated p42/44 MAP kinase. Finally, our data indicate that Drm can induce p21(Cip1) transcriptionally via a novel pathway that is independent of p53 and the p38 and p42/44 MAP kinases. These results provide evidence that Drm can function as a novel transformation suppressor and suggest that this may occur through its affect on the levels of p21(Cip1) and phosphorylated p42/44 MAPK.

Cutting edge: bone morphogenetic protein antagonists Drm/Gremlin and Dan interact with Slits and act as negative regulators of monocyte chemotaxis.

Drm/Gremlin and Dan, two homologous secreted antagonists of bone morphogenic proteins, have been shown to regulate early development, tumorigenesis, and renal pathophysiology. In this study, we report that Drm and Dan physically and functionally interact with Slit1 and Slit2 proteins. Drm binding to Slits depends on its glycosylation and is not interfered with by bone morphogenic proteins. Importantly, Drm and Dan function as inhibitors for monocyte migration induced by stromal cell-derived factor 1alpha (SDF-1alpha) or fMLP. The inhibition of SDF-1alpha-induced monocyte chemotaxis by Dan is not due to blocking the binding of SDF-1alpha to its receptor. Thus, the results identify that Drm and Dan can interact with Slit proteins and act as inhibitors of monocyte chemotaxis, demonstrating a previously unidentified biological role for these proteins.