Different dosage forms of gonadotropin-releasing hormone agonist with endocrine therapy in premenopausal hormone receptor-positive breast cancer.

BACKGROUND: Despite the wide use of a 3-month gonadotropin-releasing hormone (GnRH) agonist for ovarian function suppression in premenopausal breast cancer patients, it remains unclear whether it is as effective and safe as a 1-month GnRH agonist regimen when combined with selective estrogen receptor modulators or aromatase inhibitors, especially in younger patients. METHODS: This retrospective cohort study included 1109 premenopausal hormone receptor-positive breast cancer patients treated with GnRH agonist plus selective estrogen receptor modulator or aromatase inhibitor. The estradiol (E2) inhibition rate within 1-24 months after treatment with 1-month or 3-month GnRH agonist in cohorts and different subgroups was analyzed. RESULTS: Following 1:1 propensity score matching, 950 patients with a mean age of 39 years and a median follow-up of 46 months were included. Both the 1-month and 3-month groups achieved more than 90% E2 inhibition within 24 months (94.53% vs 92.84%, with a 95% confidence interval for the difference ranging from -4.78% to 1.41%), confirming the noninferiority of 3-month GnRH agonist. Both 1-month and 3-month GnRH agonist rapidly and consistently reduced E2 levels. Of the patients, 60 (6.3%) experienced incomplete ovarian function suppression, with similar rates in the 1-month and 3-month groups (5.5% vs 7.2%). Incomplete ovarian function suppression mainly occurred within the first 12 months, with age younger than 40 years and no prior chemotherapy being the risk factors. Similar disease-free survival and overall survival were found in the 1-month and 3-month groups and in patients with complete and incomplete ovarian function suppression (P > .05). CONCLUSIONS: The ovarian function suppression with 3-month GnRH agonist was not inferior to that with 1-month GnRH agonist, regardless of age or combination with a selective estrogen receptor modulator or an aromatase inhibitor.

LncRNA EILA promotes CDK4/6 inhibitor resistance in breast cancer by stabilizing cyclin E1 protein.

CDK4/6 inhibitors (CDK4/6i) plus endocrine therapy are now standard first-line therapy for advanced HR+/HER2- breast cancer, but developing resistance is just a matter of time in these patients. Here, we report that a cyclin E1-interacting lncRNA (EILA) is up-regulated in CDK4/6i-resistant breast cancer cells and contributes to CDK4/6i resistance by stabilizing cyclin E1 protein. EILA overexpression correlates with accelerated cell cycle progression and poor prognosis in breast cancer. Silencing EILA reduces cyclin E1 protein and restores CDK4/6i sensitivity both in vitro and in vivo. Mechanistically, hairpin A of EILA binds to the carboxyl terminus of cyclin E1 protein and hinders its binding to FBXW7, thereby blocking its ubiquitination and degradation. EILA is transcriptionally regulated by CTCF/CDK8/TFII-I complexes and can be inhibited by CDK8 inhibitors. This study unveils the role of EILA in regulating cyclin E1 stability and CDK4/6i resistance, which may serve as a biomarker to predict therapy response and a potential therapeutic target to overcome resistance.

HDAC7 inhibits cell proliferation via NudCD1/GGH axis in triple-negative breast cancer.

Triple-negative breast cancer (TNBC) is the most malignant subtype of breast cancer. In the absence of effective molecular markers for TNBC, there is an urgent clinical need for promising therapeutic target for TNBC. Histone deacetylases (HDACs), key regulators for chromatin remodeling and gene expression, have been suggested to play critical roles in cancer development. However, little is known ~the functions and implications of HDACs in TNBC treatment in the future. By analyzing the expression and prognostic significance of HDAC family members in TNBC through TCGA and METABRIC databases, HDAC7 was found to be downregulated in TNBC samples and the survival of patients with lower expression of HDAC7 was shorter. Furthermore, HDAC7 was negatively associated with NudC domain containing 1 (NudCD1) and γ-glutamyl hydrolase (GGH). Loss of NudCD1 or GGH predicted improved overall survival time (OS) of patients with TNBC. In vitro experiments showed that silencing of HDAC7 enhanced TNBC cell proliferation, while overexpression HDAC7 inhibited TNBC cell proliferation. The results of functional experiments confirmed that HDAC7 negatively modulated GGH and NudCD1 expression. Furthermore, decrease of NudCD1 or GGH inhibited cell proliferation. Notably, the HDAC7-NudCD1/GGH axis was found to be associated with NK cell infiltration. Overall, the present study revealed a novel role of HDAC7-NudCD1/GGH axis in TNBC, which might provide a promising treatment strategy for patients with TNBC.