The activity of the catalytic domain of the orphan MAP kinase ERK5 is increased by Ras but not Raf-1 in cells, which suggests that ERK5 might mediate Raf-independent signaling by Ras. We found that ...Raf-1 does contribute to Ras activation of ERK5 but in a manner that does not correlate with Raf-1 catalytic activity. A clue to the mechanism of action of Raf-1 on ERK5 comes from the observation that endogenous Raf-1 binds to endogenous ERK5, suggesting the involvement of regulatory protein-protein interactions. This interaction is specific because Raf-1 binds only to ERK5 and not ERK2 or SAPK. Finally, we demonstrate the ERK5/MEK5 pathway is required for Raf-dependent cellular transformation and that a constitutively active form of MEK5, MEK5DD, synergizes with Raf to transform NIH 3T3 cells. These observations suggest that ERK5 plays a large role in Raf-1-mediated signal transduction.
Background: The recently identified RASSF1 locus is located within a 120-kilobase region of chromosome 3p21.3 that frequently undergoes allele loss in lung and breast cancers. We explored the ...hypothesis that RASSF1 encodes a tumor suppressor gene for lung and breast cancers. Methods: We assessed expression of two RASSF1 gene products, RASSF1A and RASSF1C, and the methylation status of their respective promoters in 27 non-small-cell lung cancer (NSCLC) cell lines, in 107 resected NSCLCs, in 47 small-cell lung cancer (SCLC) cell lines, in 22 breast cancer cell lines, in 39 resected breast cancers, in 104 nonmalignant lung samples, and in three breast and lung epithelial cultures. We also transfected a lung cancer cell line that lacks RASSF1A expression with vectors containing RASSF1A complementary DNA to determine whether exogenous expression of RASSF1A would affect in vitro growth and in vivo tumorigenicity of this cell line. All statistical tests were two-sided. Results: RASSF1A messenger RNA was expressed in nonmalignant epithelial cultures but not in 100% of the SCLC, in 65% of the NSCLC, or in 60% of the breast cancer lines. By contrast, RASSF1C was expressed in all nonmalignant cell cultures and in nearly all cancer cell lines. RASSF1A promoter hypermethylation was detected in 100% of SCLC, in 63% of NSCLC, in 64% of breast cancer lines, in 30% of primary NSCLCs, and in 49% of primary breast tumors but in none of the nonmalignant lung tissues. RASSF1A promoter hypermethylation in resected NSCLCs was associated with impaired patient survival (P = .046). Exogenous expression of RASSF1A in a cell line lacking expression decreased in vitro colony formation and in vivo tumorigenicity. Conclusion: RASSF1A is a potential tumor suppressor gene that undergoes epigenetic inactivation in lung and breast cancers through hypermethylation of its promoter region.
While an overwhelming majority of patients diagnosed with cancer express willingness to participate in clinical trials, only a fraction will enroll onto a research protocol.
To identify critical ...barriers to trial enrollment to translate findings into actionable practice changes that increase cancer clinical trial enrollment.
This survey study included designated site contacts at oncology practices with teams who were highly involved with the Association of Community Cancer Centers (ACCC) Community Oncology Research Institute (ACORI) clinical trials activities, all American Society of Clinical Oncology (ASCO)-ACCC collaboration pilot sites, and/or sites providing care to at least 25% African American and Hispanic residents. To determine participation trends among health care practices in oncology-focused research, identify barriers to clinical trial implementation and operation, and establish unmet needs for cancer clinics interested in trial participation, a 34-question survey was designed. Survey questions were defined within 3 categories: cancer center demographic characteristics, clinical trial characteristics, and referral practices. The survey was distributed through email and was open from June 20 through October 5, 2022.
Participation in and barriers to conducting oncology trials in different community oncology settings.
The survey was distributed to 100 cancer centers, with completion by 58 centers (58%) across 25 states. Fifty-two centers (88%) reported that they conduct therapeutic clinical trials, of which 33 (63%) were from urban settings, 11 (21%) were from suburban settings, and 8 (15%) were from rural settings. Only 25% of rural practices (2 of 8) offered phase 1 trials, compared with 67% of urban practices (22 of 33) (P = .01). Respondents noted challenges in conducting research, including patient recruitment (27 respondents 52%), limited staffing (27 52%), and nonrelevant trials for their patient population (25 48%). Among sites not offering therapeutic trials, barriers to research conduct included limited infrastructure, funding, and staffing. Most centers (46 of 58 79%) referred patients to outside centers for clinical trial enrollment, particularly in the context of late-stage disease and/or disease progression. Only 17 of these sites (37%) had established protocols for patient follow-up subsequent to outside referral.
In this national survey study of barriers to clinical trial implementation, most sites offered therapeutic trials, but there were significant disparities in trial availability across care settings. Furthermore, fundamental deficiencies in trial support infrastructure limited research activity, including within programs currently conducting research as well as at sites interested in future clinical research opportunities. These results identify crucial unmet needs for oncology clinics to effectively offer clinical trials to patients seeking care.
B-lymphocyte stimulator/B-cell activating factor (BLyS/BAFF) and a proliferation-inducing ligand (APRIL), members of the tumor necrosis family of ligands, are expressed by monocytes, macrophages, and ...dendritic cells, and increased expression of these ligands is noted in lymphomas and plasma cell malignancies. BLyS and APRIL are essential for the survival of normal and malignant B lymphocytes, and altered expression of BLyS or APRIL or the receptors B-cell maturation, transmembrane activator and calcium-modulating cyclophilin ligand interactor, or BAFF-R have been reported in various B-cell malignancies, including B-cell non-Hodgkin's lymphoma, chronic lymphocytic leukemia, Hodgkin's lymphoma, multiple myeloma, and Waldenström's macroglobulinemia. Levels of BLyS (in the tumor and in the serum) increased with the transformation of the tumors to a more aggressive phenotype. A high BLyS level inversely correlated with a poor median overall survival, presence of constitutional symptoms, and increased levels of lactate dehydrogenase in patients with non-Hodgkin's lymphoma. Additionally, patients who responded to therapy had a lower BLyS level than those with progressive disease. Several agents targeting BLyS and APRIL are currently being pursued in phase I clinical studies in patients with B-cell malignancies.
Vascular endothelial growth factor (VEGF), a key regulator of angiogenesis, is critical for growth of human pancreatic adenocarcinoma. Preclinical studies demonstrate that blockade of VEGF activity ...can control the growth of pancreatic tumors in mice. In this study, we evaluated the efficacy of 2C3, an antibody that inhibits VEGF receptor 2 activation by human VEGF, to inhibit the growth of human pancreatic adenocarcinoma in mice.
Human pancreatic cancer cell lines (MiaPaca-2, Panc-1, and Capan-1) were used to establish xenografts in nu/nu mice. The expression of VEGF and its receptors was determined in each cell line. Proliferation of tumor cells in vitro and tumor growth in vivo in the presence of 2C3 or a control antibody was evaluated. The effect of 2C3 on tumor weight, total vessel density, number of pericyte-associated vessels, and tumor perfusion was determined, and the level of 2C3 in the serum of animals was measured by enzyme-linked immunosorbent assay.
2C3 did not affect the proliferation of cells in culture. 2C3 was present and active in the serum of tumor-bearing animals treated with 2C3, and these animals showed a decrease in tumor burden compared with control-treated mice. Therapy with 2C3 resulted in reduced vascular function, measured by a decrease in vessel density and in the percentage of vessels associated with pericytes. Furthermore, tumors derived from Capan-1 cells demonstrated decreased perfusion after treatment with 2C3.
Blockade of VEGF receptor 2 activation by tumor-derived VEGF decreases tumor vessel function and growth of some human pancreatic adenocarcinoma cell lines in mice.
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