Emerging drugs for endometrial cancer

HNRNPA2B1-mediated m6A modification of FOXM1 promotes drug resistance and inhibits ferroptosis in endometrial cancer via regulation of LCN2

N6-methyladenosine (m6A) methylation is an extensive posttranscriptional RNA modification, and it is associated with various cellular responses, especially in tumor progression. An m6A "reader"-HNRNPA2B1 has been found oncogenic in multiple malignancies. As a key proliferation-related transcription factor, forkhead box protein M1 (FOXM1) is involved in tumorigenesis. Here, we elucidated the underlying mechanism by which HNRNPA2B1-mediated modification of FOXM1 promotes endometrial cancer (EC). The GSE115810 dataset was used to analyze the upregulated gene mRNA in late-stage EC tissues. The expression levels of HNRNPA2B1, FOXM1, and LCN2 in EC samples were shown by western blotting and qPCR. The interaction among HNRNPA2B1, FOXM1, and LCN2 in EC cells was detected using bioinformatics analysis, RNA immunoprecipitation (RIP), RNA pull-down, RNA decay analysis, and luciferase reporter experiments. Cisplatin (DDP)-resistant EC cells were constructed using HEC-1-A and HEC-1-B cells, named HEC-1-A/DDP and HEC-1-B/DDP, respectively. Proliferation, migration, and invasiveness in treated HEC-1-A/DDP and HEC-1-B/DDP cells were detected by EdU, wound healing, and transwell assays. Ferroptosis-resistant gene expression, MDA level, and ROS level were measured. The m6A modification level in EC tissues was elevated. HNRNPA2B1 and FOXM1 levels were upregulated in EC. HNRNPA2B1 expression was positively related to FOXM1 expression in EC samples, and HNRNPA2B1 bound to the 3'UTR of FOXM1 and stabilized FOXM1 mRNA via m6A modification. FOXM1 positively regulated LCN2 expression in EC cells by binding to the LCN2 promotor. Knockdown of FOXM1 downregulated ferroptosis-resistant gene expression and increased MDA and ROS levels in DDP-resistant EC cells. Rescue assays revealed that LCN2 overexpression eliminated the effects mediated by FOXM1 knockdown on the proliferation, migration, invasiveness, and ferroptosis in DDP-resistant EC cells. In conclusion, HNRNPA2B1-mediated mA modification of FOXM1 facilitates drug resistance and inhibits ferroptosis in EC cells by upregulating LCN2 expression.

CircRAPGEF5 interacts with RBFOX2 to confer ferroptosis resistance by modulating alternative splicing of TFRC in endometrial cancer

Endometrial cancer (EC) is one of the most common gynecological cancers. Ferroptosis is a newly identified form of cell death characterized by iron-dependent lipid peroxide accumulation. Circular RNAs (circRNAs) have emerged as critical regulators for cancer development. However, circRNA-mediated modulation of ferroptosis in EC is yet to be clarified. In this study, we found that circRAPGEF5 expression was elevated in EC tissues compared to the normal endometrial tissues. In vitro and in vivo functional analysis demonstrated that circRAPGEF5 facilitates rapid proliferation of EC cells. RNA binding protein fox-1 homolog 2 (RBFOX2), a splicing regulator, was identified as the protein interacts with circRAPGEF5. Further studies revealed that circRAPGEF5 can bind to the Fox-1 C-terminal domain of RBFOX2 and induces specific exon exclusion of TFRC through obstructing the binding of RBFOX2 to pre-mRNA. As a result, elevated levels of circRAPGEF5 lead to ferroptosis resistance via the decreased labile iron pool and attenuated lipid peroxide production in EC cells. Additionally, a series of gain- and loss-of-function experiments demonstrated that knocking down or overexpressing RBFOX2 reversed the effects of knocking down or overexpressing circRAPGEF5 in EC cells. Finally, it is revealed that circRAPGEF5 promote the formation of TFRC with exon-4 skipping and confer ferroptosis resistance in EC cells through the interaction with RBFOX2. Collectively, these findings provide new insight into the molecular mechanism in which circRNAs mediate mediates ferroptosis via modulating alternative splicing, and circRAPGEF5/RBFOX2 splicing axis could be a promising therapeutic target for treating EC.

Correlation of MACC1/c-Myc Expression in Endometrial Carcinoma with Clinical/Pathological Features or Prognosis

Background

Endometrial carcinoma (EC) is a type of female reproductive malignant tumor, the incidence of which is generally 20~30%. Multiple factors and genes are involved in the regulation of EC occurrence and progression. This study aimed to measure the expressions of MACC1 and c-Myc in EC patients to analyze their correlation with pathological features of EC.

Material/Methods

A total of 60 EC patients were recruited in the experimental group, while another cohort of 30 people with endometrial inflammatory hyperplasia was enrolled in the control group. The levels of serum MACC1 and c-Myc were measured by ELISA, and the protein expressions in EC cancer tissues, tumor-adjacent tissues, and controlled endometrial tissues were detected by immunohistochemistry (IHC). The correlation between gene expression and clinical/pathological features was then determined.

Results

Our data indicate that the level of serum MACC1 and c-Myc in the experimental group was 1.67±0.08 ng/ml and 1.78±0.07 ng/ml, respectively, both of which were significantly higher than that of the control group (p<0.05). However, no significant difference was found among levels of serum MACC1 or c-Myc at different TNM stages (p>0.05). In cancer tissues, the positive rate of MACC1 or c-Myc was 73.3% and 78.3%, respectively, which were significantly higher than that in adjacent or control tissues (p<0.05). MACC1/c-Myc expression was correlated with TNM stage, primary infiltration grade, lymph node metastasis, and distal metastasis (p<0.05).

Conclusions

MACC1 and c-Myc are highly expressed in serum and tumor tissues of EC patients. Both are correlated with TNM stage, primary infiltration, and lymph node or distal metastasis, which provides a scientific basis for the development of new biomarkers for the diagnosis of endometrial carcinoma.