Mechanisms of Breast Cancer Stem Cell Specification and Self-Renewal Mediated by Hypoxia-Inducible Factor 1

Many advanced human cancers contain regions of intratumoral hypoxia, with O2 gradients extending to anoxia. Hypoxia-inducible factors (HIFs) are activated in hypoxic cancer cells and drive metabolic reprogramming, vascularization, invasion, and metastasis. Hypoxia induces breast cancer stem cell (BCSC) specification by inducing the expression and/or activity of the pluripotency factors KLF4, NANOG, OCT4, and SOX2. Recent studies have identified HIF-1-dependent expression of PLXNB3, NARF, and TERT in hypoxic breast cancer cells. PLXNB3 binds to and activates the MET receptor tyrosine kinase, leading to activation of the SRC non-receptor tyrosine kinase and subsequently focal adhesion kinase, which promotes cancer cell migration and invasion. PLXNB3-MET-SRC signaling also activates STAT3, a transcription factor that mediates increased NANOG gene expression. Hypoxia-induced NARF binds to OCT4 and serves as a coactivator by stabilizing OCT4 binding to the KLF4, NANOG, and SOX2 genes and by stabilizing the interaction of OCT4 with KDM6A, a histone demethylase that erases repressive trimethylation of histone H3 at lysine 27, thereby increasing KLF4, NANOG, and SOX2 gene expression. In addition to increasing pluripotency factor expression by these mechanisms, HIF-1 directly activates expression of the TERT gene encoding telomerase, the enzyme required for maintenance of telomeres, which is required for the unlimited self-renewal of BCSCs. HIF-1 binds to the TERT gene and recruits NANOG, which serves as a coactivator by promoting the subsequent recruitment of USP9X, a deubiquitinase that inhibits HIF-1α degradation, and p300, a histone acetyltransferase that mediates acetylation of H3K27, which is required for transcriptional activation.

Teaching Everyone Everywhere All at Once: Leveraging Social Media to Implement a Multisite Fungal Diagnostics Curriculum

Background

Environmental fungi are threats to personal and public health. Fungal in vitro diagnostics help diagnose invasive fungal infections (IFIs), but clinicians remain underinformed about their use and interpretation. Given the increasing use of social media to share infectious diseases-related content, we designed and implemented a multisite Twitter-based curriculum focused on IFIs and related diagnostics.

Methods

Questions were posted through a dedicated Twitter account twice weekly over 8 weeks. We surveyed clinicians at 3 US academic centers before and after completion of the curriculum and interviewed a subset of participants. We undertook quantitative and qualitative evaluations and reviewed Twitter analytics.

Results

We surveyed 450 participants. One hundred twenty-one participants (27%) completed the knowledge assessment precurriculum, 68 (15%) postcurriculum, and 53 (12%) pre- and postcurriculum. We found a significant increase (72% vs 80%, P = .005) in the percentage of correct answers in the pre- versus postcurriculum knowledge assessments. Perceived benefits included a well-executed curriculum that facilitated engagement with appropriately detailed tweetorials from a dedicated Twitter account. Perceived barriers included lack of awareness of tweetorial posts and timing, competing priorities, and the coronavirus disease 2019 pandemic. The Twitter account accrued 1400 followers from 65 countries during the 8-week period. Tweets with multiple-choice questions had a median of 14 904 impressions (interquartile range [IQR], 12 818-16 963), 798 engagements (IQR, 626-1041), and an engagement rate of 6.1% (IQR, 4.2%-6.6%).

Conclusions

Educators can leverage social media to share content with a large audience and improve knowledge while being mindful of the barriers associated with implementing a curriculum on social media.

Changes in Cardiovascular Health during Young Adulthood and Subclinical Atherosclerosis in Middle Age: The CARDIA Study

Background and aims

The benefits of reaching ideal cardiovascular health (CVH) are well known, but it is unclear whether positive CVH changes from young adulthood to middle age reduce subclinical atherosclerosis risk. This study examined associations of changes in CVH from young adulthood to middle age and CVH in young adulthood with subclinical atherosclerosis.

Methods

Data was analyzed from the Coronary Artery Risk Development in Young Adults (CARDIA) study. CVH was examined at years 0 and 20 using Life Simple 7 metrics from AHA guideline. Coronary artery calcium (CAC) was identified at years 20 and 25. Carotid intima-media thickness (IMT) was identified at year 20.

Results

Among 2,935 participants (56.2% women, 46.7% black), the change of CVH score was -1.26 (2.13). For per 1-unit increase in CVH at baseline, the adjusted odds ratios (ORs) of presence of CAC and IMT were 0.81 (95% CI 0.78, 0.86) and 0.85 (95% CI 0.76, 0.94), respectively. For per 1-unit increase in CVH changes, the adjusted ORs of CAC and IMT were 0.86 (95% CI 0.82, 0.90) and 0.81 (95% CI 0.73, 0.90). Compared with stable moderate CVH, improvement from moderate to high was associated with a lower risk of CAC (0.64 [95% CI 0.43, 0.96]), while retrogression from moderate to low was associated with a higher risk of CAC (1.45 [95% CI 1.19, 1.76]).

Conclusions

Positive changes of CVH during young adulthood are associated with negative subclinical atherosclerosis risk in middle age, indicating the importance of reaching an ideal cardiovascular health status through young adulthood.

Specialized germline P-bodies are required to specify germ cell fate in Caenorhabditis elegans embryos

In animals with germ plasm, specification of the germline involves 'germ granules', cytoplasmic condensates that enrich maternal transcripts in the germline founder cells. In Caenorhabditis elegans embryos, P granules enrich maternal transcripts, but surprisingly P granules are not essential for germ cell fate specification. Here, we describe a second condensate in the C. elegans germ plasm. Like canonical P-bodies found in somatic cells, 'germline P-bodies' contain regulators of mRNA decapping and deadenylation and, in addition, the intrinsically-disordered proteins MEG-1 and MEG-2 and the TIS11-family RNA-binding protein POS-1. Embryos lacking meg-1 and meg-2 do not stabilize P-body components, misregulate POS-1 targets, mis-specify the germline founder cell and do not develop a germline. Our findings suggest that specification of the germ line involves at least two distinct condensates that independently enrich and regulate maternal mRNAs in the germline founder cells. This article has an associated 'The people behind the papers' interview.

Impact of Asleep and 24-Hour Blood Pressure Data on the Prevalence of Masked Hypertension by Race/Ethnicity

BACKGROUND

We pooled ambulatory blood pressure monitoring data from 5 US studies, including the Jackson Heart Study (JHS), the Coronary Artery Risk Development in Young Adults (CARDIA) study, the Masked Hypertension Study, the Improving the Detection of Hypertension Study, and the North Carolina Masked Hypertension Study. Using a cross-sectional study design, we estimated differences in the prevalence of masked hypertension by race/ethnicity when out-of-office blood pressure (BP) included awake, asleep, and 24-hour BP vs. awake BP alone.

METHODS

We restricted the analyses to participants with office systolic BP (SBP) <130 mm Hg and diastolic BP (DBP) <80 mm Hg. High awake BP was defined as mean SBP/DBP ≥130/80 mm Hg, high asleep BP as mean SBP/DBP ≥110/65 mm Hg, and high 24-hour BP as mean SBP/DBP ≥125/75 mm Hg.

RESULTS

Among participants not taking antihypertensive medication (n = 1,292), the prevalence of masked hypertension with out-of-office BP defined by awake BP alone or by awake, asleep, or 24-hour BP was 34.5% and 48.7%, respectively, among non-Hispanic White, 39.7% and 67.6% among non-Hispanic Black, and 19.4% and 35.1% among Hispanic participants. After multivariable adjustment, non-Hispanic Black were more likely than non-Hispanic White participants to have masked hypertension by asleep or 24-hour BP but not awake BP (adjusted odds ratio [OR] 2.14 95% confidence interval [CI] 1.45-3.15) and by asleep or 24-hour BP and awake BP (OR 1.61; 95% CI 1.12-2.32) vs. not having masked hypertension.

CONCLUSIONS

Assessing asleep and 24-hour BP measures increases the prevalence of masked hypertension more among non-Hispanic Black vs. non-Hispanic White individuals.

Remnant cholesterol predicts cardiovascular disease beyond LDL and ApoB: a primary prevention study

AIMS

Emerging evidence suggests that remnant cholesterol (RC) promotes atherosclerotic cardiovascular disease (ASCVD). We aimed to estimate RC-related risk beyond low-density lipoprotein cholesterol (LDL-C) and apolipoprotein B (apoB) in patients without known ASCVD.

METHODS AND RESULTS

We pooled data from 17 532 ASCVD-free individuals from the Atherosclerosis Risk in Communities study (n = 9748), the Multi-Ethnic Study of Atherosclerosis (n = 3049), and the Coronary Artery Risk Development in Young Adults (n = 4735). RC was calculated as non-high-density lipoprotein cholesterol (non-HDL-C) minus calculated LDL-C. Adjusted Cox models were used to estimate the risk for incident ASCVD associated with log RC levels. We also performed discordance analyses examining relative ASCVD risk in RC vs. LDL-C discordant/concordant groups using difference in percentile units (>10 units) and clinically relevant LDL-C targets. The mean age of participants was 52.3 ± 17.9 years, 56.7% were women and 34% black. There were 2143 ASCVD events over the median follow-up of 18.7 years. After multivariable adjustment including LDL-C and apoB, log RC was associated with higher ASCVD risk [hazard ratio (HR) 1.65, 95% confidence interval (CI) 1.45-1.89]. Moreover, the discordant high RC/low LDL-C group, but not the low RC/high LDL-C group, was associated with increased ASCVD risk compared to the concordant group (HR 1.21, 95% CI 1.08-1.34). Similar results were shown when examining discordance across clinical cutpoints.

CONCLUSIONS

In ASCVD-free individuals, elevated RC levels were associated with ASCVD independent of traditional risk factors, LDL-C, and apoB levels. The mechanisms of RC association with ASCVD, surprisingly beyond apoB, and the potential value of targeted RC-lowering in primary prevention need to be further investigated.