DNAJC12 as a Mediator Between ESR1 and ERBB4 in Breast Carcinoma Cells

Downregulation of DNAJC12 Expression Predicts Worse Survival for ER-Positive Breast Cancer Patients

Background

DNAJC12 (DnaJ heat shock protein family (Hsp40) member C12) encodes a member of the molecular chaperone Hsp40/DnaJ family, which are important protein folding and proteostasis regulators. Its role as a biomarker has been studied for a limited number of cancer types. Objectives: Here, we sought to investigate the potential of DNAJC12 mRNA and protein expression as a prognostic and predictive biomarker for breast cancer (BC).

Methods

Using in silico analysis and data from immunohistochemistry analysis (IHC) of 292 samples from patients with primary BC, we determined the expression pattern and prognostic value of DNAJC12 mRNA and protein expression.

Results

From online publicly available data, we were able to identify the transcripts of DNAJC12 as differentially expressed in patients with different clinicopathological characteristics, such as ER status (P < .001), PR status (P < .001), HER2 status (P < .010) and molecular subtype (P ⩽ .001). We also found DNAJC12 to be a potential prognostic predictor for overall survival, disease-free survival, and responsiveness to treatment; a low DNAJC12 mRNA expression is commonly associated with a worse prognosis. Using IHC analysis, we showed that low DNAJC12 protein-level expression is also associated with a worse prognosis in patients with all subtypes of BC and patients with Luminal BC, and its expression is significantly different between patients with different tumor size classifications (T1/T2 vs T3/T4; P = .013) or with different lymph node involvement (N0 vs N+; P = .005).

Conclusion

Our findings suggested a potential role for DNAJC12 as a prognostic and predictive biomarker for BC.

DNAJC12 causes breast cancer chemotherapy resistance by repressing doxorubicin-induced ferroptosis and apoptosis via activation of AKT

BACKGROUND

Chemotherapy is a primary treatment for breast cancer (BC), yet many patients develop resistance over time. This study aims to identify critical factors contributing to chemoresistance and their underlying molecular mechanisms, with a focus on reversing this resistance.

METHODS

We utilized samples from the Gene Expression Omnibus (GEO) and West China Hospital to identify and validate genes associated with chemoresistance. Functional studies were conducted using MDA-MB-231 and MCF-7 cell lines, involving gain-of-function and loss-of-function approaches. RNA sequencing (RNA-seq) identified potential mechanisms. We examined interactions between DNAJC12, HSP70, and AKT using co-immunoprecipitation (Co-IP) assays and established cell line-derived xenograft (CDX) models for in vivo validations.

RESULTS

Boruta analysis of four GEO datasets identified DNAJC12 as highly significant. Patients with high DNAJC12 expression showed an 8 % pathological complete response (pCR) rate, compared to 38 % in the low expression group. DNAJC12 inhibited doxorubicin (DOX)-induced cell death through both ferroptosis and apoptosis. Combining apoptosis and ferroptosis inhibitors completely reversed DOX resistance caused by DNAJC12 overexpression. RNA-seq suggested that DNAJC12 overexpression activated the PI3K-AKT pathway. Inhibition of AKT reversed the DOX resistance induced by DNAJC12, including reduced apoptosis and ferroptosis, restoration of cleaved caspase 3, and decreased GPX4 and SLC7A11 levels. Additionally, DNAJC12 was found to increase AKT phosphorylation in an HSP70-dependent manner, and inhibiting HSP70 also reversed the DOX resistance. In vivo studies confirmed that AKT inhibition reversed DNAJC12-induced DOX resistance in the CDX model.

CONCLUSION

DNAJC12 expression is closely linked to chemoresistance in BC. The DNAJC12-HSP70-AKT signaling axis is crucial in mediating resistance to chemotherapy by suppressing DOX-induced ferroptosis and apoptosis. Our findings suggest that targeting AKT and HSP70 activities may offer new therapeutic strategies to overcome chemoresistance in BC.