The Role of the CREB Protein Family Members and the Related Transcription Factors in Radioresistance Mechanisms

PFDN4 as a Prognostic Marker Was Associated with Chemotherapy Resistance through CREBP1/AURKA Pathway in Triple-Negative Breast Cancer

Breast cancer is the most common malignancy and its incidence is increasing. It is currently mainly treated by clinical chemotherapy, but chemoresistance remains poorly understood. Prefolded proteins 4 (PFDN4) are molecular chaperone complexes that bind to newly synthesized polypeptides and allow them to fold correctly to stabilize protein formation. This study aimed to investigate the role of PFDN4 in chemotherapy resistance in breast cancer. Our study found that PFDN4 was highly expressed in breast cancer compared to normal tissues and was statistically significantly associated with stage, nodal status, subclasses (luminal, HER2 positive and triple negative), triple-negative subtype and disease-specific survival by TCGA database analysis. CRISPR knockout of PFDN4 inhibited the growth of 89% of breast cancer cell lines, and the triple-negative cell line exhibited a stronger inhibitory effect than the non-triple-negative cell line. High PFDN4 expression was associated with poor overall survival in chemotherapy and resistance to doxorubicin and paclitaxel through the CREBP1/AURKA pathway in the triple-negative MDAMB231 cell line. This study provides insightful evidence for the value of PFDN4 in poor prognosis and chemotherapy resistance in breast cancer patients.

mTORC2 orchestrates monocytic and granulocytic lineage commitment by an ATF5-mediated pathway

Myeloid hematopoiesis is a finely controlled consecutive developmental process, which is essential to maintain peripheral innate immune homeostasis. Herein, we found that Rictor deletion caused the remarkable reduction of granulocyte-monocyte progenitors (GMPs), monocytes, and macrophages, while the levels of neutrophils were unaffected. Adoptive transfer of Rictor-deleted GMPs or common myeloid progenitors (CMPs) in syngeneic mice showed poor re-constitution of monocytes compared to wild-type GMPs or CMPs. In addition to decreasing the proliferation of CMPs/GMPs, Rictor deletion preferentially inhibited Ly6C+ monocyte differentiation, while enhancing neutrophil differentiation, as determined by colony formation assays. mTORC2 promotes monocyte development by downregulation of the AKT-Foxo4-activating transcription factor 5 (ATF5)-mitochondrial unfolded protein response (mtUPR) pathway. Genetic overexpression of ATF5 or exposure to ethidium bromide significantly rescued monocyte/macrophage differentiation defects of Rictor-deficient myeloid progenitors. Therefore, Rictor is required for CMP/GMP proliferation and acts as an important switch to balance monocytic and granulocytic lineage commitment in bone marrow.

The Role of Krüppel-like Factors in Pancreatic Physiology and Pathophysiology

Krüppel-like factors (KLFs) belong to the family of transcription factors with three highly conserved zinc finger domains in the C-terminus. They regulate homeostasis, development, and disease progression in many tissues. It has been shown that KLFs play an essential role in the endocrine and exocrine compartments of the pancreas. They are necessary to maintain glucose homeostasis and have been implicated in the development of diabetes. Furthermore, they can be a vital tool in enabling pancreas regeneration and disease modeling. Finally, the KLF family contains proteins that act as tumor suppressors and oncogenes. A subset of members has a biphasic function, being upregulated in the early stages of oncogenesis and stimulating its progression and downregulated in the late stages to allow for tumor dissemination. Here, we describe KLFs' function in pancreatic physiology and pathophysiology.

CRISPR/Cas9-mediated mutations in both a cAMP response element and an ETS-binding site suppress FLT1 gene expression

The Fms-like tyrosine kinase-1 (FLT1) gene is expressed in various types of cells, including vascular endothelial cells and placental trophoblasts, and regulates angiogenesis, inflammation, and pregnancy. However, the basal transcriptional machinery of FLT1 is still not well understood. In this study, we first examined FLT1 promoter activity in three different types of cells, that is, trophoblast-derived cells, vascular endothelial-related cells, and HEK293 cells, using plasmid-based luciferase reporter assays, and showed that a cAMP-response element (CRE) and an ETS-binding site (EBS) are important for FLT1 expression in all cell types. To further examine the importance of these sites at the chromosomal level using HEK293 cells, we introduced CRISPR/Cas9-mediated mutations in these sites on the genomic DNA. HEK293 cells carrying these mutations clearly showed a significant decrease in endogenous FLT1 gene expression. These results suggest that CRE and EBS transcription regulatory elements are crucial for FLT1 gene expression in human tissues.