H2A.Z chaperones converge on E2F target genes for melanoma cell proliferation.

High levels of H2A.Z promote melanoma cell proliferation and correlate with poor prognosis. However, the role of the two distinct H2A.Z histone chaperone complexes SRCAP and P400-TIP60 in melanoma remains unclear. Here, we show that individual subunit depletion of SRCAP, P400, and VPS72 (YL1) results in not only the loss of H2A.Z deposition into chromatin but also a reduction of H4 acetylation in melanoma cells. This loss of H4 acetylation is particularly found at the promoters of cell cycle genes directly bound by H2A.Z and its chaperones, suggesting a coordinated regulation between H2A.Z deposition and H4 acetylation to promote their expression. Knockdown of each of the three subunits downregulates E2F1 and its targets, resulting in a cell cycle arrest akin to H2A.Z depletion. However, unlike H2A.Z deficiency, loss of the shared H2A.Z chaperone subunit YL1 induces apoptosis. Furthermore, YL1 is overexpressed in melanoma tissues, and its upregulation is associated with poor patient outcome. Together, these findings provide a rationale for future targeting of H2A.Z chaperones as an epigenetic strategy for melanoma treatment.

H2A.Z chaperones converge on histone H4 acetylation for melanoma cell proliferation.

High levels of H2A.Z promote melanoma cell proliferation and correlate with poor prognosis. However, the role of the two distinct H2A.Z histone chaperone complexes, SRCAP and P400-TIP60, in melanoma remains unclear. Here, we show that individual depletion of SRCAP, P400, and VPS72 (YL1) not only results in loss of H2A.Z deposition into chromatin, but also a striking reduction of H4 acetylation in melanoma cells. This loss of H4 acetylation is found at the promoters of cell cycle genes directly bound by H2A.Z and its chaperones, suggesting a highly coordinated regulation between H2A.Z deposition and H4 acetylation to promote their expression. Knockdown of each of the three subunits downregulates E2F1 and its targets, resulting in a cell cycle arrest akin to H2A.Z depletion. However, unlike H2A.Z deficiency, loss of the shared H2A.Z chaperone subunit YL1 induces apoptosis. Furthermore, YL1 is overexpressed in melanoma tissues, and its upregulation is associated with poor patient outcome. Together, these findings provide a rationale for future targeting of H2A.Z chaperones as an epigenetic strategy for melanoma treatment.

Racial, Ethnic, and Sex Diversity in Academic Medical Leadership.

Importance: For the past 50 years, significant gaps have existed in gender and racial diversity across various medical specialties, despite the many benefits of a diverse physician workforce. One proposed approach to increasing diversity is top-down diversification, in which diverse leadership results in increased minority and female workforce representation. Objective: To investigate the changes in academic medical leadership diversity from 2007 to 2019 and to assess the recent leadership diversity of various specialties compared with the averages across all specialties. Design, Setting, and Participants: This was a cross-sectional analysis of physicians in varying academic roles in 2007, 2019, and 2020. Demographic data were collected via specialized reports from the Association of American Medical Colleges. Included were 4 primary care specialties (internal medicine, family medicine, pediatrics, obstetrics/gynecology [OB/GYN] and 4 surgical specialties (orthopedic surgery, neurologic surgery, otolaryngology [ENT], general surgery). Study participants were faculty, program directors, and chairpersons. Data were analyzed for the years 2007, 2019, and 2020. Intervention: Self-reporting of demographic information to residency programs collected via the Graduate Medical Education Track Survey. Main Outcomes and Measures: Proportions of each race/ethnicity and sex among cohorts of participants and comparisons between them. Results: The total number of individuals investigated included 186 210 faculty from 2019 (79 441 female [42.7%]), 6417 program directors from 2020 (2392 female [37.3%]), 1016 chairpersons from 2007 (89 female [8.8%]), and 2424 chairpersons from 2019 (435 female [17.9%]). When comparing chairperson diversity from 2007 to 2019, only internal medicine and general surgery experienced significant increases in minority (aggregate category used throughout the investigation to refer to anyone who self-identified as anything other than non-Hispanic White) representation (90% increase [11.7 percentage points, from 13.0% in 2007 to 24.7% in 2019]; P = .01 and 96% increase [13.0 percentage points, from 13.5% in 2007 to 26.5% in 2019]; P < .001), respectively; meanwhile, several specialties saw significant increases in female representation during this period (family medicine by 107.4%, P =.002; pediatrics by 83.1%, P =.006; OB/GYN by 53.2%, P =.045; orthopedic surgery by +4.1 percentage points, P =.04; general surgery by 226.9%, P =.005). In general, surgical specialties had lower leadership diversity than the average diversity of all residency programs, whereas primary care specialties had similar or increased diversity. Conclusions and Relevance: Study results suggest that some specialties have made significant contributions toward bridging diversity gaps whereas others continue to lag behind. Our recommendations to improve academic medical leadership diversity include programs and institutions (1) publishing efforts and outcomes of diversity representation, (2) incorporating a representative demographic for leadership selection committees, and (3) actively promoting the importance of diversity throughout the selection process.

WNTinib is a multi-kinase inhibitor with specificity against ß-catenin mutant hepatocellular carcinoma.

Hepatocellular carcinoma (HCC) is a leading cause of cancer-related deaths worldwide. ß-Catenin (CTNNB1)-mutated HCC represents 30% of cases of the disease with no precision therapeutics available. Using chemical libraries derived from clinical multi-kinase inhibitor (KI) scaffolds, we screened HCC organoids to identify WNTinib, a KI with exquisite selectivity in CTNNB1-mutated human and murine models, including patient samples. Multiomic and target engagement analyses, combined with rescue experiments and in vitro and in vivo efficacy studies, revealed that WNTinib is superior to clinical KIs and inhibits KIT/mitogen-activated protein kinase (MAPK) signaling at multiple nodes. Moreover, we demonstrate that reduced engagement on BRAF and p38α kinases by WNTinib relative to several multi-KIs is necessary to avoid compensatory feedback signaling-providing a durable and selective transcriptional repression of mutant ß-catenin/Wnt targets through nuclear translocation of the EZH2 transcriptional repressor. Our studies uncover a previously unknown mechanism to harness the KIT/MAPK/EZH2 pathway to potently and selectively antagonize CTNNB1-mutant HCC with an unprecedented wide therapeutic index.

Racial, Ethnic, and Gender Diversity in Academic Orthopaedic Surgery Leadership.

BACKGROUND: Multiple investigations in the past 50 years have documented a lack of racial/ethnic and gender diversity in the orthopaedic surgery workforce when compared with other specialties. Studies in other industries suggest that diversification of leadership can help diversify the underlying workforce. This study investigates changes in racial/ethnic and gender diversity of orthopaedic surgery leadership from 2007 to 2019 and compares leadership diversity to that of other surgical and nonsurgical specialties, specifically in terms of chairpersons and program directors. METHODS: Demographic data were collected from The Journal of the American Medical Association and the Association of American Medical Colleges. Aggregate data were utilized to determine the racial, ethnic, and gender composition of academic leadership for 8 surgical and nonsurgical specialties in 2007 and 2019. Comparative analysis was conducted to identify changes in diversity among chairpersons between the 2 years. Furthermore, current levels of diversity in orthopaedic leadership were compared with those of other specialties. RESULTS: A comparative analysis of diversity among program directors revealed that orthopaedic surgery had significantly lower minority representation (20.5%) when compared with the nonsurgical specialties (adjusted p < 0.01 for all) and, with the exception of neurological surgery, had the lowest proportion of female program directors overall, at 9.0% (adjusted p < 0.001 for all). From 2007 to 2019, orthopaedic surgery experienced no change in minority representation among chairpersons (adjusted p = 0.73) but a significant increase in female representation among chairpersons, from 0.0% (0 of 102) to 4.1% (5 of 122) (adjusted p = 0.04). Lastly, a significant decrease in minority and female representation was observed when comparing the diversity of 2019 orthopaedic faculty to orthopaedic leadership in 2019/2020 (p < 0.05 for all). CONCLUSIONS: Diversity in orthopaedic surgery leadership has improved on some key fronts, specifically in gender diversity among chairpersons. However, a significant decrease in minority and gender representation was observed between 2019 orthopaedic faculty and 2019/2020 orthopaedic leadership (p < 0.05), which was a trend shared by other specialties. These findings may suggest a more pervasive problem in diversity of medical leadership that is not only limited to orthopaedic surgery.

Loss of Myeloid-Specific TGF-ß Signaling Decreases CTHRC1 to Downregulate bFGF and the Development of H1993-Induced Osteolytic Bone Lesions.

The role of myeloid cell-specific TGF-ß signaling in non-small-cell lung cancer (NSCLC)-induced osteolytic bone lesion development is unknown. We used a genetically engineered mouse model, Tgfbr2LysMCre knockout (KO), which has a loss of TGF-ß signaling specifically in myeloid lineage cells, and we found that the area of H1993 cell-induced osteolytic bone lesions was decreased in Tgfbr2LysMCre KO mice, relative to the area in control littermates. The bone lesion areas were correlated with tumor cell proliferation, angiogenesis, and osteoclastogenesis in the microenvironment. The smaller bone lesion area was partially rescued by bFGF, which was expressed by osteoblasts. Interestingly, bFGF was able to rescue the osteoclastogenesis, but not the tumor cell proliferation or angiogenesis. We then focused on identifying osteoclast factors that regulate bFGF expression in osteoblasts. We found that the expression and secretion of CTHRC1 was downregulated in osteoclasts from Tgfbr2LysMCre KO mice; CTHRC1 was able to promote bFGF expression in osteoblasts, possibly through the Wnt/ß-catenin pathway. Functionally, bFGF stimulated osteoclastogenesis and inhibited osteoblastogenesis, but had no effect on H1993 cell proliferation. On the other hand, CTHRC1 promoted osteoblastogenesis and H1993 cell proliferation. Together, our data show that myeloid-specific TGF-ß signaling promoted osteolytic bone lesion development and bFGF expression in osteoblasts; that osteoclast-secreted CTHRC1 stimulated bFGF expression in osteoblasts in a paracrine manner; and that CTHRC1 and bFGF had different cell-specific functions that contributed to bone lesion development.

Click Chemistry Approaches to Expand the Repertoire of PEG-based Fluorinated Surfactants for Droplet Microfluidics.

We report the novel and simplified synthesis of fluorinated surfactants for droplet microfluidics. The range of applications of droplet microfluidics has greatly expanded during the last decade thanks to its ability to manipulate and process tiny amount of sample and reagents at high throughput in independent reactors. A critical component of the technology is the formulation of the immiscible oil phase that contains surfactants to stabilize droplets. The success of droplet microfluidics relies mostly on a single fluorinated formulation that uses a PFPE-PEG tri-block surfactant. The synthesis of this surfactant is laborious and requires skills in synthetic chemistry preventing the wider community to explore the synthesis of alternate surfactants. We sought to provide a simplified synthesis for novel PFPE-PEG surfactants based on click chemistry approaches such as copper-catalyzed azide-alkyne cycloaddition (CuAAC) and UV-activated thiol-yne reactions. Our strategy is based on converting a moisture sensitive intermediate typically used in the synthesis of the tri-block PFPE-PEG surfactant into a stable and click ready molecule. We successfully combined that fluorinated tail with differently functionalized PEG and glycerol ethoxylate molecules to generate surfactants with diverse structures via CuACC and thiol-yne reactions. We report the characterization, biocompatibility and ability to stabilize emulsions of those surfactants, as well as the unique advantages and challenges of the strategy.

Correction: Click chemistry approaches to expand the repertoire of PEG-based fluorinated surfactants for droplet microfluidics.

[This corrects the article DOI: 10.1039/C8RA01254G.].