American Society of Clinical Oncology Road to Recovery Report: Learning From the COVID-19 Experience to Improve Clinical Research and Cancer Care.

This report presents the American Society of Clinical Oncology's (ASCO's) evaluation of the adaptations in care delivery, research operations, and regulatory oversight made in response to the coronavirus pandemic and presents recommendations for moving forward as the pandemic recedes. ASCO organized its recommendations for clinical research around five goals to ensure lessons learned from the COVID-19 experience are used to craft a more equitable, accessible, and efficient clinical research system that protects patient safety, ensures scientific integrity, and maintains data quality. The specific goals are: (1) ensure that clinical research is accessible, affordable, and equitable; (2) design more pragmatic and efficient clinical trials; (3) minimize administrative and regulatory burdens on research sites; (4) recruit, retain, and support a well-trained clinical research workforce; and (5) promote appropriate oversight and review of clinical trial conduct and results. Similarly, ASCO also organized its recommendations regarding cancer care delivery around five goals: (1) promote and protect equitable access to high-quality cancer care; (2) support safe delivery of high-quality cancer care; (3) advance policies to ensure oncology providers have sufficient resources to provide high-quality patient care; (4) recognize and address threats to clinician, provider, and patient well-being; and (5) improve patient access to high-quality cancer care via telemedicine. ASCO will work at all levels to advance the recommendations made in this report.

Novel characteristics of the biological properties of the yeast Saccharomyces cerevisiae eukaryotic initiation factor 2A.

Eukaryotic initiation factor 2A (eIF2A) has been shown to direct binding of the initiator methionyl-tRNA (Met-tRNA(i)) to 40 S ribosomal subunits in a codon-dependent manner, in contrast to eIF2, which requires GTP but not the AUG codon to bind initiator tRNA to 40 S subunits. We show here that yeast eIF2A genetically interacts with initiation factor eIF4E, suggesting that both proteins function in the same pathway. The double eIF2A/eIF4E-ts mutant strain displays a severe slow growth phenotype, which correlated with the accumulation of 85% of the double mutant cells arrested at the G(2)/M border. These cells also exhibited a disorganized actin cytoskeleton and elevated actin levels, suggesting that eIF2A might be involved in controlling the expression of genes involved in morphogenic processes. Further insights into eIF2A function were gained from the studies of eIF2A distribution in ribosomal fractions obtained from either an eIF5BDelta (fun12Delta) strain or a eIF3b-ts (prt1-1) strain. It was found that the binding of eIF2A to 40 and 80 S ribosomes was not impaired in either strain. We also found that eIF2A functions as a suppressor of Ure2p internal ribosome entry site-mediated translation in yeast cells. The regulation of expression from the URE2 internal ribosome entry site appears to be through the levels of eIF2A protein, which has been found to be inherently unstable with a half-life of approximately 17 min. It was hypothesized that this instability allows for translational control through the level of eIF2A protein in yeast cells.

p53 activation results in rapid dephosphorylation of the eIF4E-binding protein 4E-BP1, inhibition of ribosomal protein S6 kinase and inhibition of translation initiation.

p53 is an important regulator of cell cycle progression and apoptosis, and inactivation of p53 is associated with tumorigenesis. Although p53 exerts many of its effects through regulation of transcription, this protein is also found in association with ribosomes and several mRNAs have been identified that are translationally controlled in a p53-dependent manner. We have utilized murine erythroleukemic cells that express a temperature-sensitive p53 protein to determine whether p53 also functions at the level of translation. The data presented here demonstrate that p53 causes a rapid decrease in translation initiation. Analysis of several potential mechanisms for regulating protein synthesis shows that p53 has selective effects on the phosphorylation of the eIF4E-binding protein, 4E-BP1, and the activity of the p70 ribosomal protein S6 kinase. These data provide evidence that modulation of translational activity constitutes a further mechanism by which the growth inhibitory effects of p53 may be mediated.

Characterization of mammalian eIF2A and identification of the yeast homolog.

To begin the physical characterization of eukaryotic initiation factor (eIF) 2A, a translation initiation factor that binds Met-tRNA(i), tryptic peptides from rabbit reticulocyte eIF2A were analyzed to obtain amino acid sequence information. Sequences for 8 peptides were matched to three different expressed sequence tag clones. The sequence predicted for eIF2A is 585 amino acids. Matching of the cDNA sequence to the human genome revealed that the eIF2A mRNA is made up of 15 or 16 exons, and the gene is contained on chromosome 3. A homolog in Saccharomyces cerevisiae was identified, YGR054W, which is a non-essential gene. Hemagglutinin-tagged yeast eIF2A localizes on both 40 S and 80 S ribosomes. A knockout of both eIF2A and eIF5B yielded a "synthetically sick" yeast strain with a severe slow growth phenotype. The phenotype of this double mutant and the biochemical localization suggest that eIF2A participates in translation initiation. eIF2A does not appear to participate in re-initiation as the DeltaeIF2A strain shows the same level of GCN4 induction with amino acid starvation as seen in wild type yeast. The lack of any apparent phenotype in the DeltaeIF2A strain suggests that eIF2A functions in a minor pathway, perhaps internal initiation or in the translation of a small number of specific mRNAs.

S6 phosphorylation-independent pathways regulate translation of 5'-terminal oligopyrimidine tract-containing mRNAs in differentiating hematopoietic cells.

Synthesis of new ribosomes is an energy costly and thus highly regulated process. Ribosomal protein synthesis is controlled by regulating translation of the corresponding ribosomal protein (rp)mRNAs. In mammalian cells a 5'-terminal oligopyrimidine tract (TOP) is a conserved feature of these mRNAs that has been demonstrated to be essential for their translational regulation. Translation of TOP mRNAs has been proposed to be regulated by phosphorylation of ribosomal protein S6, which is a common effect of mitogenic stimulation of cells. However, as demonstrated here, S6 phosphorylation is not detectable in murine erythroleukemia (MEL) or other hematopoietic cells. The absence of S6 phosphorylation appears to be due to the action of a phosphatase that acts downstream of S6 kinase, presumably on S6 itself. Despite the absence of changes in S6 phosphorylation, translation of TOP mRNAs is repressed during differentiation of MEL cells. These data demonstrate the existence of a mechanism for regulating S6 phosphorylation that is distinct from kinase activation, as well as the existence of mechanisms for regulating translation of TOP mRNAs that are independent of S6 phosphorylation.