YTHDF1 shapes "cold" tumor and inhibits CD8+ T cells infiltration and function in breast cancer.

While YTH N6-methyladenosine RNA binding protein 1 (YTHDF1) was recognized as a crucial contributor in the development and immune-related regulation of various types of tumors, its function in the immune response of breast cancer has largely remained uninvestigated. Through analysis of public databases, we found YTHDF1 as a highly expressed gene in breast cancers and confirmed this finding in breast cancer cells and clinical specimens from our center. Subsequently, we examined the link between YTHDF1 expression and immune cells and molecules by utilizing immune-related public databases and algorithm. We further validated our findings through cellular and animal experiments, as well as RNA sequencing. YTHDF1 was found highly expressed in tumor tissues of breast cancer, which negatively correlated with patient survival. The downregulation of YTHDF1 promoted the expression of pro-inflammatory markers and improved the anti-cancer ability of immune cells in breast cancer. RNA sequencing analysis revealed that YTHDF1 knockdown resulted in enrichment of differential genes in signal transduction pathways. Additionally, in vitro experiments showed that immune cells had higher cytotoxicity against breast cancer cells with decreased YTHDF1 expression. Moreover, in vivo studies indicated that YTHDF1 promoted breast cancer growth while inhibiting CD8+ T cell infiltration and function. Our study demonstrates that YTHDF1 plays a crucial role in establishing a "cold" tumor microenvironment in breast cancer by inhibiting the release of pro-inflammatory cytokines from cancer cells. As a result, the infiltration and functional differentiation of anti-tumor CD8+ T cells are hindered, ultimately resulting in the immune evasion of breast cancer.

The Efficacy of Low-Kilovoltage X-Rays Intraoperative Radiation as Boost for Breast Cancer: A Systematic Review and Meta-Analysis.

Background: Intraoperative radiotherapy (IORT) is a novel promising technology that may replace external beam radiation therapy (EBRT) as boost for patients receiving breast-conserving surgery. To better evaluate the efficacy of IORT using low-kilovoltage (low-kV) X-rays as boost, we presented this meta-analysis according to the PRISMA checklist. Methods: Studies reported survival outcomes of intraoperative radiation using low-kilovoltage X-rays system (Intrabeam®, Carl Zeiss Meditec, Dublin, CA, USA) as boost were identified through electronic bibliographic database: PUBMED. The meta-analysis module in Stata (16.0) is used to pool the studies. A Poisson regression model is used to predict a 5-year local recurrence rate. Results: Twelve studies including 3006 cases were included in the final analysis, with a median follow-up of 55 months weighted by sample size. The pooled local recurrence rate is 0.39% per person-year (95% CI: 0.15%-0.71%), with a low degree of heterogeneity (I2 = 0%). The predicted 5-year local recurrence rate was 3.45%. No difference in pooled local recurrence rate was found between non-neoadjuvant patients studies and neoadjuvant patients studies (0.41% per person-year vs. 0.58% per person-year, P = 0.580). Conclusions: This study shows that low-kV IORT is an effective method as boost in breast cancer patients, with a low pooled local recurrence rate and low predicted 5-year local recurrence rate. Besides, no difference in the local recurrence rate was found between non-neoadjuvant patients studies and neoadjuvant patients studies. Low-kV IORT boost may be a promising alternative to EBRT boost in the future, which is being tested in the ongoing TARGIT-B trial.

The application of contrast-enhanced ultrasound for sentinel lymph node evaluation and mapping in breast cancer patients.

Background: To retrospectively investigate the application of contrast-enhanced ultrasound on sentinel lymph node (SLN-CEUS) for SLN evaluation and mapping in breast cancer patients. Methods: Patients diagnosed with breast cancer at the First Affiliated Hospital of Sun Yat-sen University from June 2019 to March 2021 were conveniently evaluated by SLN-CEUS. The results of SLN-CEUS and B mode-ultrasound (BUS) were collected and compared. For patients who only underwent SLN-CEUS, we conducted a 1:1 propensity score matching (PSM). The diagnostic parameters, including sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), false negative rate (FNR), false positive rate (FPR), and proportion of undetermined diagnoses were compared between the SLN-CEUS and BUS cohorts. The identification rate and FNR of sentinel lymph node biopsy (SLNB) were also assessed. Results: There were 327 patients in each of the SLN-CEUS and BUS cohorts. Among the entire cohort, both NPV [90.2% (95% CI, 85.4-93.5%) vs. 83.5% (95% CI, 77.8-88.0%), P=0.048] and accuracy [80.7% (95% CI, 76.5-85.0%) vs. 73.7% (95% CI, 68.9-78.5%), P<0.001] of SLN-CEUS were significantly higher than those of BUS. In non-neoadjuvant treatment (NAT) patients, the NPV [94.7% (95% CI, 89.9-97.4%) vs. 85.5% (95% CI, 79.1-90.2%), P=0.007] and accuracy [87.6% (95% CI, 83.2-92.0%) vs. 76.0% (95% CI, 70.4-81.5%), P<0.001] of SLN-CEUS were significantly higher than those of BUS. In NAT patients, no difference in diagnostic efficacy was found. The proportion of undetermined diagnoses of SLN-CEUS was significantly lower than that of BUS (5.8% vs. 15.3%, P<0.001). The identification rate of SLN-CEUS in overall patients, non-NAT patients, and NAT patients was 94.2%, 96.3%, and 89.9%, respectively. The FNR of SLNB with the blue-dye tracer in combination with SLN-CEUS in overall patients, non-NAT patients, and NAT patients was 7.3%, 4.0%, and 12.5%, respectively. Conclusions: Compared to BUS, SLN-CEUS is a better technique for diagnosing SLNs in early breast cancer patients, showing superiority in multiple diagnostic parameters. However, the diagnostic value of SLN-CEUS in NAT patients is still undetermined. SLN-CEUS is a promising mapping method in SLNB, with a high identification rate and a low FNR when used in combination with a blue-dye tracer.

The Synergistic Effect of Proanthocyanidin and HDAC Inhibitor Inhibit Breast Cancer Cell Growth and Promote Apoptosis.

Histone deacetylase inhibitor (HDACi) is a drug mainly used to treat hematological tumors and breast cancer, but its inhibitory effect on breast cancer falls short of expectations. Grape seed proanthocyanidin extract (GSPE) with abundant proanthocyanidins (PAs) has been explored for its inhibition of HDAC activity in vitro and in vivo. To enhance HDACi's effectiveness, we investigated the potential of PA to synergistically enhance HDACi chidamide (Chi), and determined the underlying mechanism. We evaluated the half-inhibitory concentration (IC50) of PA and Chi using the cell counting kit 8 (CCK8), and analyzed drugs' synergistic effect with fixed-ratio combination using the software Compusyn. Breast cancer cell's phenotypes, including short-term and long-term proliferation, migration, invasion, apoptosis, and reactive oxygen species (ROS) levels, were assessed via CCK8, clone-formation assay, wound-healing test, Transwell Matrigel invasion assay, and flow-cytometry. Protein-protein interaction analysis (PPI) and KEGG pathway analysis were used to determine the underlying mechanism of synergy. PA + Chi synergistically inhibited cell growth in T47D and MDA-MB-231 breast cancer cell lines. Short-term and long-term proliferation were significantly inhibited, while cell apoptosis was promoted. Ten signaling pathways were identified to account for the synergistic effect after RNA sequencing. Their synergism may be closely related to the steroid biosynthesis and extracellular matrix (ECM) receptor interaction pathways. PA + Chi can synergistically inhibit breast cancer cell growth and proliferation, and promote apoptosis. These effects may be related to steroid biosynthesis or the ECM receptor pathway.