Barriers to hydroxyurea use from the perspectives of providers, individuals with sickle cell disease, and families: Report from a U.S. regional collaborative.

Sickle cell disease (SCD) is an inherited blood disorder that affects about 100,000 people in the U.S., primarily Blacks/African-Americans. A multitude of complications negatively impacts quality of life. Hydroxyurea has been FDA approved since 1998 as a disease-modifying therapy for SCD, but is underutilized. Negative and uninformed perceptions of hydroxyurea and barriers to its use hinder adherence and promotion of the medication. As the largest real-world study to date that assessed hydroxyurea use for children and adults with SCD, we gathered and analyzed perspectives of providers, individuals with SCD, and families. Participants provided information about socio-demographics, hospital and emergency admissions for pain, number of severe pain episodes interfering with daily activities, medication adherence, and barriers to hydroxyurea. Providers reported on indications for hydroxyurea, reasons not prescribed, and current laboratory values. We found that hydroxyurea use was reported in over half of eligible patients from this large geographic region in the U.S., representing a range of sickle cell specialty clinical settings and practices. Provider and patient/caregiver reports about hydroxyurea use were consistent with one another; adults 26 years and older were least likely to be on hydroxyurea; and the likelihood of being on hydroxyurea decreased with one or more barriers. Using the intentional and unintentional medication nonadherence framework, we found that, even for patients on hydroxyurea, challenges to taking the medicine at the right time and forgetting were crucial unintentional barriers to adherence. Intentional barriers such as worry about side effects and "tried and it did not work" were important barriers for young adults and adults. For providers, diagnoses other than HgbSS or HgbS-ß0 thalassemia were associated with lower odds of prescribing, consistent with evidence-based guidelines. Our results support strengthening provider understanding and confidence in implementing existing SCD guidelines, and the importance of shared decision making. Our findings can assist providers in understanding choices and decisions of families; guide individualized clinical discussions regarding hydroxyurea therapy; and help with developing tailored interventions to address barriers. Addressing barriers to hydroxyurea use can inform strategies to minimize similar barriers in the use of emerging and combination therapies for SCD.

ProteinInferencer: Confident protein identification and multiple experiment comparison for large scale proteomics projects.

Shotgun proteomics generates valuable information from large-scale and target protein characterizations, including protein expression, protein quantification, protein post-translational modifications (PTMs), protein localization, and protein-protein interactions. Typically, peptides derived from proteolytic digestion, rather than intact proteins, are analyzed by mass spectrometers because peptides are more readily separated, ionized and fragmented. The amino acid sequences of peptides can be interpreted by matching the observed tandem mass spectra to theoretical spectra derived from a protein sequence database. Identified peptides serve as surrogates for their proteins and are often used to establish what proteins were present in the original mixture and to quantify protein abundance. Two major issues exist for assigning peptides to their originating protein. The first issue is maintaining a desired false discovery rate (FDR) when comparing or combining multiple large datasets generated by shotgun analysis and the second issue is properly assigning peptides to proteins when homologous proteins are present in the database. Herein we demonstrate a new computational tool, ProteinInferencer, which can be used for protein inference with both small- or large-scale data sets to produce a well-controlled protein FDR. In addition, ProteinInferencer introduces confidence scoring for individual proteins, which makes protein identifications evaluable. This article is part of a Special Issue entitled: Computational Proteomics.

The butterfly effect in cancer: a single base mutation can remodel the cell.

We have compared the proteome, transcriptome, and metabolome of two cell lines: the human breast epithelial line MCF-10A and its mutant descendant MCF-10A-H1047R. These cell lines are derived from the same parental stock and differ by a single amino acid substitution (H1047R) caused by a single nucleotide change in one allele of the PIK3CA gene, which encodes the catalytic subunit p110α of PI3K (phosphatidylinositol 3-kinase). They are considered isogenic. The H1047R mutation of PIK3CA is one of the most frequently encountered somatic cancer-specific mutations. In MCF-10A, this mutation induces an extensive cellular reorganization that far exceeds the known signaling activities of PI3K. The changes are highly diverse, with examples in structural protein levels, the DNA repair machinery, and sterol synthesis. Gene set enrichment analysis reveals a highly significant concordance of the genes differentially expressed in MCF-10A-H1047R cells and the established protein and RNA signatures of basal breast cancer. No such concordance was found with the specific gene signatures of other histological types of breast cancer. Our data document the power of a single base mutation, inducing an extensive remodeling of the cell toward the phenotype of a specific cancer.

Membrane protein CNNM4-dependent Mg2+ efflux suppresses tumor progression.

Intracellular Mg(2+) levels are strictly regulated; however, the biological importance of intracellular Mg(2+) levels and the pathways that regulate them remain poorly understood. Here, we determined that intracellular Mg(2+) is important in regulating both energy metabolism and tumor progression. We determined that CNNM4, a membrane protein that stimulates Mg(2+) efflux, binds phosphatase of regenerating liver (PRL), which is frequently overexpressed in malignant human cancers. Biochemical analyses of cultured cells revealed that PRL prevents CNNM4-dependent Mg(2+) efflux and that regulation of intracellular Mg(2+) levels by PRL and CNNM4 is linked to energy metabolism and AMPK/mTOR signaling. Indeed, treatment with the clinically available mTOR inhibitor rapamycin suppressed the growth of cancer cells in which PRL was overexpressed. In ApcΔ(14/+) mice, which spontaneously form benign polyps in the intestine, deletion of Cnnm4 promoted malignant progression of intestinal polyps to adenocarcinomas. IHC analyses of tissues from patients with colon cancer demonstrated an inverse relationship between CNNM4 expression and colon cancer malignancy. Together, these results indicate that CNNM4-dependent Mg(2+) efflux suppresses tumor progression by regulating energy metabolism.