Kruppel-like Factors 3 Regulates Migration and Invasion of Gastric Cancer Cells Through NF-κB Pathway.

Context: The poorly understood regulatory mechanisms impede gastric cancer therapy. Kruppel-like factors (KLFs) are associated with the development of various tumors, The studies on the role of the KLF transcription factor 13 (KLF13) in gastric cancer progression haven't been studied. Objective: The current study aimed to investigate the role of KLF13 in the migration and invasion of gastric cancer and the regulatory mechanism of KLF13 in gastric cancer progression. Design: The research team performed a laboratory study. Setting: The study took place at the Zengcheng District People's Hospital of Guangzhou in Zengcheng, China. Participants: In addition to using normal gastric cells, GES1, and seven gastric cancer cell lines, the research team compared the fresh, gastric cancer tissues (T) and paired, adjacent, noncancerous gastric tissues (ANT) from eight patients undergoing surgical resection at the hospital. The research team also downloaded the data for 33 gastric cancer tissues and adjacent, normal gastric tissues from the Cancer Genome Atlas' TCGA database. Intervention: The research team used: (1) short hairpin RNAs (shRNAs) to knock down KLF13, (2) wound healing and transwell invasion analyses to determine the effects of KLF13 on the migration and invasion of gastric cancer, and (3) a Luciferase reporter assay to determine the effects of KLF13 on nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) activity. Results: KLF13 was upregulated in gastric cancer cells and tissues, and the patients with a high KLF13 expression had poor outcome. Downregulation of KLF13 significantly inhibited the migration and invasion of gastric cancer cells. Mechanistically, downregulation of KLF13 significantly inhibited NF-κB activity, and its targets such as: (1) snail family transcriptional repressor 1 (SNAI1 or Snail), (2) snail family transcriptional repressor 2 (SNAI2 or Slug), (3) zinc finger e-box binding homeobox 1 (ZEB1), (4) Smad interacting protein 1 (Sip1), (5) twist family basic helix-loop-helix (BHLH) transcription factor (Twist), (6) matrix metallopeptidase 2 (MMP2), and (7) MMP9. Tumor necrosis factor alpha (TNF-α) can activate NF-κB. Treating with TNF-α can reverse the effects of KLF13 downregulation on migration and invasion, confirming that KLF13 promotes the migration and invasion of gastric cancer cells through activating the NF-κB pathway. Conclusions: KLF13 promoted the migration and invasion of gastric cancer cells through activating the NF-κB pathway, providing a new target for gastric cancer therapy.

Generation of human melanocytes from induced pluripotent stem cells.

Epidermal melanocytes play an important role in protecting the skin from UV rays, and their functional impairment results in pigment disorders. Additionally, melanomas are considered to arise from mutations that accumulate in melanocyte stem cells. The mechanisms underlying melanocyte differentiation and the defining characteristics of melanocyte stem cells in humans are, however, largely unknown. In the present study, we set out to generate melanocytes from human iPS cells in vitro, leading to a preliminary investigation of the mechanisms of human melanocyte differentiation. We generated iPS cell lines from human dermal fibroblasts using the Yamanaka factors (SOX2, OCT3/4, and KLF4, with or without c-MYC). These iPS cell lines were subsequently used to form embryoid bodies (EBs) and then differentiated into melanocytes via culture supplementation with Wnt3a, SCF, and ET-3. Seven weeks after inducing differentiation, pigmented cells expressing melanocyte markers such as MITF, tyrosinase, SILV, and TYRP1, were detected. Melanosomes were identified in these pigmented cells by electron microscopy, and global gene expression profiling of the pigmented cells showed a high similarity to that of human primary foreskin-derived melanocytes, suggesting the successful generation of melanocytes from iPS cells. This in vitro differentiation system should prove useful for understanding human melanocyte biology and revealing the mechanism of various pigment cell disorders, including melanoma.

A functional screen for Krüppel-like factors that regulate the human gamma-globin gene through the CACCC promoter element.

Krüppel-like factors (KLFs) have been systematically screened as potential candidates to regulate human gamma-globin gene expression through its CACCC element. Initially, 21 human proteins that have close sequence similarity to EKLF/KLF1, a known regulator of the human beta-globin gene, were identified. The phylogenetic relationship of these 22 KLF/Sp1 proteins was determined. KLF2/LKLF, KLF3/BKLF, KLF4/GKLF, KLF5/IKLF, KLF8/BKLF3, KLF11/FKLF, KLF12/AP-2rep and KLF13/FKLF2 were chosen for functional screening. Semi-quantitative RT-PCR demonstrated that all eight of these candidates are present in human erythroid cell lines, and that the expression of the KLF2, 4, 5 and 12 mRNAs changed significantly upon erythroid differentiation. Each of the eight KLF mRNAs is expressed in mouse erythroid tissues, throughout development. UV cross-linking assays suggest that multiple erythroid proteins from human cell lines and chicken primary cells interact with the gamma-globin CACCC element. In co-transfection assays in K562 cells, it was demonstrated that KLF2, 5 and 13 positively regulate, and KLF8 negatively regulates, the gamma-globin gene through the CACCC promoter element. The data collectively suggest that multiple KLFs may participate in the regulation of gamma-globin gene expression and that KLF2, 5, 8 and 13 are prime candidates for further study.