SGK2 is overexpressed in colon cancer and promotes epithelial-mesenchymal transition in colon cancer cells

Overexpression of TSPAN8 in consensus molecular subtype 3 colorectal cancer

BACKGROUND

Recently, consensus molecular subtypes (CMSs) have been proposed as a robust transcriptome-based classification system for colorectal cancer (CRC). Tetraspanins (TSPANs) are transmembrane proteins. They have been associated with the development of numerous malignancies, including CRC, through their role as "master organizers" for multi-molecular membrane complexes. No previous study has investigated the correlation between TSPANs and CMS classification. Herein, we investigated the expression of TSPANs in patient-derived primary CRC tissues and their CMS classifications.

METHODS

RNA samples were derived from primary CRC tissues (n = 100 patients diagnosed with colorectal adenocarcinoma) and subjected to RNA sequencing for transcriptome-based CMS classification and TSPAN-relevant analyses. Immunohistochemistry (IHC) and immunofluorescence (IF) stains were conducted to observe the protein expression level. To evaluate the relative biological pathways, gene-set enrichment analysis was performed.

RESULTS

Of the highly expressed TSPAN genes in CRC tissues (TSPAN8, TSPAN29, and TSPAN30), TSPAN8 was notably overexpressed in CMS3-classified primary tissues. The overexpression of TSPAN8 protein in CMS3 CRC was also observed by IHC and IF staining. As a result of gene-set enrichment analysis, TSPAN8 may potentially play a role in organizing signaling complexes for kinase-based metabolic deregulation in CMS3 CRC.

CONCLUSIONS

The present study reports the overexpression of TSPAN8 in CMS3 CRC. This study proposes TSPAN8 as a subtype-specific biomarker for CMS3 CRC. This finding provides a foundation for future CMS-based studies of CRC, a complex disease and the second leading cause of cancer mortality worldwide.

SGK2 promotes prostate cancer metastasis by inhibiting ferroptosis via upregulating GPX4

Recent research has shown that ferroptosis, the iron-dependent accumulation of lipid peroxides that leads to cell death, suppresses cancer metastasis. However, the role of ferroptosis in prostate cancer metastasis has not been completely elucidated. In the current study, we identified the essential role of serum/glucocorticoid regulated kinase 2 (SGK2) in promoting prostate cancer metastasis by inhibiting ferroptosis. We found that the expression of SGK2 was higher in metastatic prostate cancer and predicted poor clinical outcomes. SGK2 knockdown inhibited the metastatic capacity of prostate cancer cells in vivo and in vitro, while SGK2 overexpression inhibited ferroptosis and facilitated prostate cancer metastasis by phosphorylating the Thr-24 and Ser-319 sites of forkhead box O1 (FOXO1). This process induced the translocation of FOXO1 from the nucleus to the cytoplasm, relieving the inhibitory effect of FOXO1 on glutathione peroxidase 4 (GPX4). These findings delineated a novel role of SGK2 in ferroptosis regulation of prostate cancer metastasis, identifying a new key pathway driving prostate cancer metastasis and potentially providing new treatment strategies for metastatic prostate cancer.

Revealing the Potential Application of EC-Synthetic Retinoid Analogues in Anticancer Therapy

(1) Background and Aim: All-trans retinoic acid (ATRA) induces differentiation and inhibits growth of many cancer cells. However, resistance develops rapidly prompting the urgent need for new synthetic and potent derivatives. EC19 and EC23 are two synthetic retinoids with potent stem cell neuro-differentiation activity. Here, these compounds were screened for their in vitro antiproliferative and cytotoxic activity using an array of different cancer cell lines. (2) Methods: MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay, AV/PI (annexin V-fluorescein isothiocyanate (FITC)/propidium iodide (PI)), cell cycle analysis, immunocytochemistry, gene expression analysis, Western blotting, measurement of glutamate and total antioxidant concentrations were recruited. (3) Results: HepG2, Caco-2, and MCF-7 were the most sensitive cell lines; HepG2 (ATRA; 36.2, EC19; 42.2 and EC23; 0.74 µM), Caco-2 (ATRA; 58.0, EC19; 10.8 and EC23; 14.7 µM) and MCF-7 (ATRA; 99.0, EC19; 9.4 and EC23; 5.56 µM). Caco-2 cells were selected for further biochemical investigations. Isobologram analysis revealed the combined synergistic effects with 5-fluorouracil with substantial reduction in IC50. All retinoids induced apoptosis but EC19 had higher potency, with significant cell cycle arrest at subG0-G1, -S and G2/M phases, than ATRA and EC23. Moreover, EC19 reduced cellular metastasis in a transwell invasion assay due to overexpression of E-cadherin, retinoic acid-induced 2 (RAI2) and Werner (WRN) genes. (4) Conclusion: The present study suggests that EC-synthetic retinoids, particularly EC19, can be effective, alone or in combinations, for potential anticancer activity to colorectal cancer. Further in vivo studies are recommended to pave the way for clinical applications.