Inhibition of FBP1 expression by KMT5A through TWIST1 methylation is one of the mechanisms leading to chemoresistance in breast cancer.

Lysine methyltransferase 5A (KMT5A) is the sole mammalian enzyme known to catalyse the mono­methylation of histone H4 lysine 20 and non­histone proteins such as p53, which are involved in the occurrence and progression of numerous cancers. The present study aimed to determine the function of KMT5A in inducing docetaxel (DTX) resistance in patients with breast carcinoma by evaluating glucose metabolism and the underlying mechanism involved. The upregulation or downregulation of KMT5A­related proteins was examined after KMT5A knockdown in breast cancer (BRCA) cells by Tandem Mass Tag proteomics. Through differential protein expression and pathway enrichment analysis, the upregulated key gluconeogenic enzyme fructose­1,6­bisphosphatase 1 (FBP1) was discovered. Loss of FBP1 expression is closely related to the development and prognosis of cancers. A dual­luciferase reporter gene assay confirmed that KMT5A inhibited the expression of FBP1 and that overexpression of FBP1 could enhance the chemotherapeutic sensitivity to DTX through the suppression of KMT5A expression. The KMT5A inhibitor UNC0379 was used to verify that DTX resistance induced by KMT5A through the inhibition of FBP1 depended on the methylase activity of KMT5A. According to previous literature and interaction network structure, it was revealed that KMT5A acts on the transcription factor twist family BHLH transcription factor 1 (TWIST1). Then, it was verified that TWSIT1 promoted the expression of FBP1 by using a dual­luciferase reporter gene experiment. KMT5A induces chemotherapy resistance in BRCA cells by promoting cell proliferation and glycolysis. After the knockdown of the KMT5A gene, the FBP1 related to glucose metabolism in BRCA was upregulated. KMT5A knockdown expression and FBP1 overexpression synergistically inhibit cell proliferation and block cells in the G2/M phase. KMT5A inhibits the expression of FBP1 by methylating TWIST1 and weakening its promotion of FBP1 transcription. In conclusion, KMT5A was shown to affect chemotherapy resistance by regulating the cell cycle and positively regulate glycolysis­mediated chemotherapy resistance by inhibiting the transcription of FBP1 in collaboration with TWIST1. KMT5A may be a potential therapeutic target for chemotherapy resistance in BRCA.

GnRHa protects the ovarian reserve by reducing endoplasmic reticulum stress during cyclophosphamide-based chemotherapy.

Chemotherapy-induced ovarian dysfunction is a serious adverse effect in premenopausal patients with cancer. Gonadotrophin-releasing hormone analogs (GnRHa) protect ovarian function, but its molecular mechanisms have not yet been determined. In this study, we attempted to determine the previously unknown molecular mechanism by which such protection occurs. Serum anti-Müllerian hormone (AMH) levels were tested in tumor-bearing nude mice, a series of exploratory experiments were conducted. We discovered that GnRHa protects granulosa cells from chemotherapeutic toxicity in vivo and in vitro. We also showed that CTX-induced endoplasmic reticulum stress inhibits the secretion of AMH, and treatment with GnRHa relieves ER stress and the subsequent unfolded-protein response by modulating mTOR signaling to induce autophagy. The results of mechanistic studies indicated that GnRHa-modulated mTOR signaling to induce autophagy, which alleviated CTX-induced ER stress and promoted the secretion of AMH.

Can Anti-Müllerian Hormone Be a Reliable Biomarker for Assessing Ovarian Function in Women Postchemotherapy?

PURPOSE: The predictive value of anti-Müllerian hormone (AMH) for ovarian dysfunction postchemotherapy is controversial. This study aimed to evaluate the value of serum AMH levels clinically and theoretically. PATIENTS ANIMALS AND METHODS: We detected the serum estradiol, follicular stimulating hormone (FSH), luteinizing hormone (LH), and AMH levels in 144 premenopausal women with breast cancer receiving cyclophosphamide-based chemotherapy. The hormone levels before and postchemotherapy were compared; the correlations among the hormones and amenorrhea and menstrual recovery were analyzed. In addition, the serum AMH levels were detected randomly in 177 normal healthy women and 36 normal female C57BL/6J mice of different ages; meanwhile, the status of ovarian follicles was also examined. Furthermore, 72 Balb/c nude mice with breast cancer were randomly assigned to three groups that received different doses of cyclophosphamide (CTX) (control, 100 mg/kg, and 200 mg/kg), and the alterations in serum AMH levels and ovarian follicles were recorded and analyzed. RESULTS: Chemotherapy-induced amenorrhea was associated with prechemotherapy AMH levels, E2 levels, and FSH levels (P < 0.0001). The recovery of menstruation was associated with prechemotherapy AMH levels (P < 0.0001), but not with E2 and FSH levels (P > 0.05). In patients with breast cancer treated with chemotherapy, the serum AMH levels did not differ significantly between the pre- and post-chemotherapy periods in patients aged <35 years (P > 0.05), whereas a dramatic reduction was detected in patients aged >35 years (P < 0.0001). In healthy women, the serum AMH levels declined sharply after 35 years of age (P < 0.0001) and remained relatively stable at a younger age. Similar results were obtained in experiments using normal mice. The cancer-bearing mice exposed to 200 mg/kg CTX exhibited a significant decline in AMH levels and a remarkable decrease in the number of primordial and growing follicles (P < 0.0001). CONCLUSION: Our results indicate that AMH is an efficient marker for predicting postchemotherapy ovarian function exclusively in premenopausal female patients with breast cancer aged >35 years.

Metabolic Symbiosis in Chemoresistance: Refocusing the Role of Aerobic Glycolysis.

Cellular metabolic reprogramming is now recognized as a hallmark of tumors. Altered tumor metabolism determines the malignant biological behaviors and phenotypes of cancer. More recently, studies have begun to reveal that cancer cells generally exhibit increased glycolysis or oxidative phosphorylation (OXPHOS) for Adenosine Triphosphate(ATP)generation, which is frequently associated with drug resistance. The metabolism of drug-resistant cells is regulated by the PI3K/AKT/mTOR pathway which ultimately confer cancer cells drug resistance phenotype. The key enzymes involved in glycolysis and the key molecules in relevant pathways have been used as targets to reverse drug resistance. In this review, we highlight our current understanding of the role of metabolic symbiosis in therapeutic resistance and discuss the ongoing effort to develop metabolic inhibitors as anti-cancer drugs to overcome drug resistance to classical chemotherapy.

Locoregional surgical treatment improves the prognosis in primary metastatic breast cancer patients with a single distant metastasis except for brain metastasis.

BACKGROUND: We aimed to validate the clinical significance of locoregional surgery in improving the prognosis of primary metastatic breast cancer (pMBC). METHODS: We conducted a population-based retrospective study by analyzing clinical data obtained from the National Cancer Institute's Surveillance, Epidemiology, and End Results (SEER) database. Stratification analysis was employed to assess the effect of breast surgery on breast cancer-specific survival and overall survival. Then propensity score matching and COX regression models were employed to evaluate the survival advantages of breast surgery, if any in patients with pMBC. RESULTS: The median BCSS and OS in the surgery group were almost twice of that in the group without surgery. Breast surgery provided a survival advantage for patients with a single metastasis in the bone, liver or lung, but not in the brain. We found that axillary lymph node dissection performed in combination with specific breast surgical procedures did not result in a significant improvement in survival. Additionally, when combined with radiotherapy and/or chemotherapy, surgery significantly improved the survival and was not influenced by the molecular subtype and tumor size. Finally, using COX regression models before and after propensity score matching, breast surgery was found to reduce the risk of mortality in patients with MBC by more than 40%. CONCLUSIONS: The effect of locoregional surgery has been underestimated in pMBC patients. Surgical procedures should be seriously considered when planning combination treatments for pMBC patients with a single metastasis except for brain metastasis.

SETD7 is a prognosis predicting factor of breast cancer and regulates redox homeostasis.

SETD7 is a methyltransferase that specifically catalyzes the monomethylation of lysine 4 on histone H3. A variety of studies has revealed the role of SETD7 in posttranslational modifications of non-histone proteins. However, the prognostic value of SETD7 on breast cancer and the ability of SETD7 of regulating intrinsic redox homeostasis has never been investigated. In this study, using The Cancer Genome Atlas (TCGA) database, we revealed that SETD7 was a potential prognostic marker of breast cancer. Median survival time of patients with low SETD7 expression (18.1 years) was twice than that of SETD7 low-expressed patients (9.5 years). We demonstrated that SETD7 promoted tumor cell proliferation and prevented cell apoptosis and that SETD7 delicately maintained the redox homeostasis through regulating the levels of GSH/GSSG and ROS. Further studies indicated that SETD7 was a positive activator of KEAP1-NRF2 pathway. Using dual luciferase assay, we revealed the role of SETD7 as a transcriptional activator of antioxidant enzymes. Downregulation of SETD7 in MCF7 and MDA-MB-231 cells impaired the expression of antioxidant enzymes and induces imbalance of redox status. Together, we proposed SETD7 as a prognostic marker of breast cancer and a novel antioxidant promoter under oxidative stress in breast cancer.

Monomethyltransferase SETD8 regulates breast cancer metabolism via stabilizing hypoxia-inducible factor 1α.

SETD8 is a methyltransferase that specifically catalyzes the monomethylation of lysine 20 on histone H4. Previous studies have demonstrated that SETD8 is associated with proper cell cycle progression, DNA damage response, and transcriptional regulation. A recent study revealed that SETD8 played an important role in epithelial-mesenchymal transition (EMT) in association with TWIST and enhanced metastatic potential of breast cancer cells. However, the contribution of SETD8 to metabolism reprogramming, one hallmark of cancer, has never been reported. In this study, we report that SETD8 was a positive regulator of anabolic metabolism. SETD8 reprograms breast cancer cell metabolism through hypoxia-inducible factor 1α (HIF1α) mediated process. Mechanistic studies indicated that SETD8 stabilized HIF1α protein level through post-transcriptional regulation. Moreover, we demonstrated that SETD8 was a HIF1α transcription target. In clinical breast cancer patient tissues, we observed a positive correlation of SETD8 with HIF1α and HIF1α target genes. Taken together, we validated SETD8 as a novel metabolic reprogramming regulator, and our mechanistic studies shed light on a novel function of SETD8 in breast cancer malignant properties maintenance.