WNK1 Interaction with KEAP1 Promotes NRF2 Stabilization to Enhance the Oxidative Stress Response in Hepatocellular Carcinoma.

Cellular oxidative stress plays a key role in the development and progression of hepatocellular carcinoma (HCC). A better understanding of the processes that regulate reactive oxygen species (ROS) homeostasis could uncover improved strategies for treating HCC. Here, we identified WNK1 as an antioxidative factor and therapeutic target in HCC. In human HCC, WNK1 expression was increased and correlated with poor patient prognosis. WNK1 knockdown significantly inhibited cell proliferation and xenograft tumor growth. Mechanistically, WNK1 competed with NRF2 for binding to the partial Kelch domain of KEAP1, reducing NRF2 ubiquitination and promoting NRF2 accumulation and nuclear translocation to increase antioxidant response. WNK1 silencing increased H2O2-induced apoptosis and inhibited cell growth by elevating reactive oxygen species (ROS) levels, which could be rescued by treatment with the antioxidant N-acetylcysteine (NAC) and NRF2 activator tert-butylhydroquinone (tBHQ). Liver-specific WNK1 knockout mouse models of HCC substantiated that WNK1 promoted HCC development by regulating ROS levels. WNK463, an inhibitor of the WNK kinase family, suppressed HCC progression and altered the redox status. These findings suggest that WNK1 plays a critical role in HCC development and progression and that the WNK1-oxidative stress axis may be a promising therapeutic target for HCC.

SP1 Mediated PIK3CB Upregulation Promotes Gastric Carcinogenesis.

PIK3CB, one of catalytic subunits of PI3Ks kinase family, is implicated in several cellular processes such as cell growth, proliferation, mobility and neoplastic transformation. Its abnormal expression has been found in several human cancer types. However, the regulation pattern and function of PIK3CB in gastric cancer (GC) are still unclear. Here, we demonstrated that PIK3CB and SP1 (special protein 1) were both upregulated in GC samples compared to adjacent non-cancerous stomach tissues at mRNA and protein levels. The expression of the two genes also displayed a significant positive correlation in GC samples. Dual-luciferase assays and chromatin immunoprecipitation (ChIP) assays revealed that SP1 could bind to the -771~-605 region of the promoter of PIK3CB and enhance transcription. Furthermore, we discovered that SP1 induced AKT activation through PIK3CB and accelerated GC cell proliferation and migration in a PIK3CB/AKT signaling dependent manner. TGX-221, a PIK3CB-selective inhibitor, which can block this signaling transduction pathway, was found to inhibit the growth of GC cells and induce apoptosis in vitro, implying that it may act as a potential development agent for GC. These collective findings provide a new insight into PI3K/AKT signaling that SP1 may function as an upstream factor on PI3K, forming a new signaling axis to promote the progression of GC or other malignancies.

PIAS3 promotes ferroptosis by regulating TXNIP via TGF-ß signaling pathway in hepatocellular carcinoma.

Ferroptosis has been suggested to play a potential role in cancer therapy as an iron-dependent programmed cell death mechanism distinct from other forms. Hepatocellular carcinoma (HCC) remains a great threat, with high mortality and limited therapeutic options. The induction of ferroptosis has emerged as a novel and promising therapeutic strategy for HCC. In the present study, we identified protein inhibitor of activated STAT3 (PIAS3) as a driver of ferroptosis in HCC using TMT-based quantitative proteomics and ferroptosis-related functional assays. Mechanistically, thioredoxin-interacting protein (TXNIP) was confirmed to be PIAS3 in promoting ferroptotic cell death, based on RNA-seq analysis. Knockdown of TXNIP degrades ferroptotic susceptibility caused by PIAS3-overexpression, whereas transfection-forced reexpression of TXNIP restores sensitivity to ferroptosis in PIAS3-downregulated cells. PIAS3 interacts with SMAD2/3 to activate transforming growth factor (TGF)-ß signaling, leading to increased TXNIP expression. Our study revealed the critical role of PIAS3 in ferroptosis and a novel actionable axis-PIAS3/TGF-ß/TXNIP that could govern ferroptotic sensitivity, paving the path for using ferroptosis as an efficient approach in HCC therapies.

YTHDF2 exerts tumor-suppressor roles in gastric cancer via up-regulating PPP2CA independently of m6A modification.

BACKGROUND: YTHDF2 is one of important readers of N6-methyladenosine (m6A) modification on RNA. Growing evidence implicates that YTHDF2 takes an indispensable part in the regulation of tumorigenesis and metastasis in different cancers, but its biological functions and underlying mechanisms remain elusive in gastric cancer (GC). AIM: To investigate the clinical relevance and biological function of YTHDF2 in GC. RESULTS: Compared with matched normal stomach tissues, YTHDF2 expression was markedly decreased in gastric cancer tissues. The expression level of YTHDF2 was inversely associated with gastric cancer patients' tumor size, AJCC classification and prognosis. Functionally, YTHDF2 reduction facilitated gastric cancer cell growth and migration in vitro and in vivo, whereas YTHDF2 overexpression exhibited opposite phenotypes. Mechanistically, YTHDF2 enhanced expression of PPP2CA, the catalytic subunit of PP2A (Protein phosphatase 2A), in an m6A-independent manner, and silencing of PPP2CA antagonized the anti-tumor effects caused by overexpression of YTHDF2 in GC cells. CONCLUSION: These findings demonstrate that YTHDF2 is down-regulated in GC and its down-regulation promotes GC progression via a possible mechanism involving PPP2CA expression, suggesting that YTHDF2 may be a hopeful biomarker for diagnosis and an unrevealed treatment target for GC.

UHMK1 aids colorectal cancer cell proliferation and chemoresistance through augmenting IL-6/STAT3 signaling.

UHMK1, a serine/threonine kinase with a U2AF homology motif, is implicated in RNA processing and protein phosphorylation. Increasing evidence has indicated its involvement in tumorigenesis. However, it remains to be elucidated whether UHMK1 plays a role in the development of colorectal cancer (CRC). Here, we demonstrated that UHMK1 was frequently upregulated in CRC samples compared with adjacent normal tissue and high expression of UHMK1 predicted poor outcomes. Knockdown of UHMK1 by siRNAs restrained CRC cell proliferation and increased oxaliplatin sensitivity, whereas overexpression of UHMK1 promoted CRC cell growth and oxaliplatin resistance, suggesting that UHMK1 plays important oncogenic roles in CRC. Mechanistically, we showed that UHMK1 had a significant effect on IL6/STAT3 signaling by interacting with STAT3. The interaction of UHMK1 with STAT3 enhanced STAT3 activity in regulating gene transcription. Furthermore, we found that STAT3 could in turn transcriptionally activate UHMK1 expression in CRC cells. The complementary experiments for cell growth and oxaliplatin resistance indicated the interdependent relationship between UHMK1 and STAT3. Thus, these collective findings uncovered a new UHMK1/STAT3 positive feedback regulatory loop contributing to CRC development and chemoresistance.

A Genome-Scale CRISPR Knock-Out Screen Identifies MicroRNA-5197-5p as a Promising Radiosensitive Biomarker in Colorectal Cancer.

Radioresistance is one of the main reasons causing unsatisfactory curative effects of ionizing radiation (IR) against colorectal cancer (CRC). However, its underlying mechanisms remain unclear yet. In the present study, we applied a genome-scale CRISPR knockout screen in combination of NGS sequencing upon CRC cell lines to explore regulatory factors involved radioresistance of CRC, and 3 candidate genes were identified. Cytotoxicity of IR was determined by Cell Counting Kit-8 (CCK-8) assay, colony formation assay and apoptosis assay, and microRNA-5197-5p (miR-5197) was found to significantly enhance the cytotoxicity of IR to CRC cells. By further mechanistic investigation, we demonstrated that miR-5197 directly targeted CDK6 and inhibited its expression in RKO cells, which induced cell cycle arrest at G1/S phase and inhibited cell division, thereby radiosensitivity was enhanced by miR-5197. Our findings revealed that miR-5197 might be a critical factor regulating CRC cell radiosensitivity and provided novel insights into the development of therapeutic strategies for CRC patients who are resistant to IR.

CSNK2B contributes to colorectal cancer cell proliferation by activating the mTOR signaling.

The function of Casein kinase 2 beta (CSNK2B) in human malignancies has drawn increasing attention in recent years. However, its role in colorectal cancer (CRC) remains unclear. In the present study, we aimed to explore the expression and biological functions of CSNK2B in CRC. Public gene expression microarray data from online database and immunohistochemistry analysis demonstrated that CSNK2B was highly expressed in CRC tissues than in normal tissues. In vitro and in vivo cellular functional experiments showed that increased CSNK2B expression promoted CRC cell viability and tumorigenesis of CRC. Further western blots and rescue experiments confirmed that CSNK2B promoted CRC cell proliferation mainly by activating the mTOR signaling pathway. These findings identified CSNK2B as a novel oncogene contributing to the development of CRC.