NMNAT1 Is a Survival Factor in Actinomycin D-Induced Osteosarcoma Cell Death

SLC12A8 upregulation promotes colorectal cancer progression and chemoresistance

Background

Colorectal cancer (CRC), a prevalent gastrointestinal malignant disease, causes substantial morbidity and mortality. Identification of novel prognostic biomarkers and therapeutic targets is critically needed to improve patient outcomes. Although solute carrier family 12 member 8 (SLC12A8) has high expression in various tumors and affects tumor progression, its role in CRC remains unclear. The aim of this study was to investigate the functions of SLC12A8 in CRC.

Methods

SLC12A8 expression and its association with clinical significance in CRC patients were explored via multiple public databases, including The Cancer Genome Atlas (TCGA), Genotype-Tissue Expression (GTEx), The Human Protein Atlas (HPA), The University of ALabama at Birmingham CANcer data analysis Portal (UALCAN), and Kaplan-Meier plotter. The effects of SLC12A8 on the CRC cell apoptosis, epithelial-mesenchymal transition (EMT), reactive oxygen species (ROS) production, and sensitivity to oxaliplatin were verified by in vitro experiments.

Results

SLC12A8 expression was upregulated in CRC tissues compared with normal colorectal tissues. Furthermore, high expression of SLC12A8 was associated with poorer prognosis in CRC patients. Pathway enrichment analyses revealed SLC12A8 involvement in oxidative stress and transforming growth factor-beta (TGF-β) signaling. Experiments in CRC cells showed that SLC12A8 upregulation promoted apoptosis resistance, EMT, and inhibited ROS production. Moreover, SLC12A8 knockdown enhanced the sensitivity of CRC cells to oxaliplatin chemotherapy.

Conclusions

Our integrative analyses identify SLC12A8 as a candidate biomarker for CRC progression. Targeting SLC12A8 may improve patient responses to oxaliplatin-based treatment regimens.

Tanshinol suppresses osteosarcoma by specifically inducing apoptosis of U2-OS cells through p53-mediated mechanism

ETHNOPHARMACOLOGICAL RELEVANCE

Radix Salviae miltiorrhizae (also called Danshen in traditional Chinese medicine) is a famous herbal medicine, which has been frequently used to treat blood stasis syndrome including osteosarcoma (OS) in traditional Chinese medicine. Main components of Danshen have been assumed to exhibit anti-OS capacity. Nevertheless, tanshinol (TS, main component of Danshen)'s efficacy and mechanism in OS hasn't been clearly described ever since. This drew our attention, since OS is the most frequent primary bone carcinomas in children and adolescents, with a high incidence and fatality rate. Unfortunately, chemotherapy for OS has faced many clinical challenges due to the increasing chemoresistance and recurrence. This study was then designed to deeply explore TS's role in OS therapy.

AIM OF THE STUDY

To explore the anti-OS efficacy and mechanism of TS, we conducted in vivo and in vitro experiments by using a zebrafish xenograft model and U2-OS cells.

MATERIALS AND METHODS

CCK-8 assay, DAPI and γ-H2A.X immunofluorescence staining, and flow cytometry (apoptosis verification) were employed to determine the anti-proliferative and pro-apoptotic effects of TS. qPCR and Western blot were used to examine TS's molecular actions and mechanism on apoptosis of U2-OS cells.

RESULTS

The in vivo data showed that TS significantly inhibited U2-OS tumor growth in larval zebrafish from 2 to 20 ng/mL. In vitro data indicated that TS exerted significant anti-proliferative and pro-apoptotic effects on U2-OS cells in a dose-dependent manner. Moreover, TS has no inhibitory effect on bMSCs, suggesting its safety on normal bone-forming cells. Molecular data illustrated that TS obviously activated the p53 signaling-related proteins (p-p53, Bax, CASP3, CASP9) and its upstream JNK (p-JNK, p-c-JUN) and ATM (p-ATM) signaling molecules through phosphorylation and cleavage, followed by up-regulation of the pro-apoptotic genes, NOXA, PUMA, TP53, BAX, and BIM, and down-regulation of Bcl-2 protein.

CONCLUSION

In sum, TS specifically induced apoptosis of U2-OS cells by activating p53 signaling pathways, indicating TS as a promising candidate for OS treatment.

KDM3A-mediated SP1 activates PFKFB4 transcription to promote aerobic glycolysis in osteosarcoma and augment tumor development

BACKGROUND

Lysine-specific histone demethylase 3A (KDM3A) is a potent histone modifier that is frequently implicated in the progression of several malignancies. However, its role in aerobic glycolysis of osteosarcoma (OS) remains unclear.

METHODS

KDM3A expression in OS tissues was determined by immunohistochemistry, and that in acquired OS cells was determined by RT-qPCR and western blot assays. KDM3A was silenced in OS cells to examine cellular behaviors and the aerobic glycolysis. Stably transfected cells were injected into nude mice for in vivo experiments. The downstream targets of KDM3A were predicted by bioinformatics systems and validated by ChIP-qPCR. Rescue experiments of SP1 and PFKFB4 were performed to examine their roles in the KDM3A-mediated events.

RESULTS

KDM3A was highly expressed in OS tissues and cells. Knockdown of KDM3A weakened OS cell growth and metastasis in vivo and in vitro, and it suppressed the aerobic glycolysis in OS cells. KDM3A enhanced the transcription of SP1 by demethylating H3K9me2 on its promoter. Restoration of SP1 rescued growth and metastasis of OS cells and recovered the glycolytic flux in cells suppressed by knockdown of KDM3A. SP1 bound to the PFKFB4 promoter to activate its transcription and expression. PFKFB4 expression in OS cells was suppressed by KDM3A silencing but increased after SP1 restoration. Overexpression of PFKFB4 significantly promoted OS cell growth and metastasis as well as the glycolytic flux in cells.

CONCLUSION

This paper elucidates that upregulation of PFKFB4 mediated by the KDM3A-SP1 axis promotes aerobic glycolysis in OS and augments tumor development.