ABSTRACT
Glioblastoma is the most common cancer in the brain, resistant to conventional therapy and prone to recurrence. Therefore, it is crucial to explore novel therapeutics strategies for the treatment and prognosis of GBM. In this study, through analyzing online datasets, we elucidated the expression and prognostic value of POLR2J and its co-expressed genes in GBM patients. Functional experiments, including assays for cell apoptosis and cell migration, were used to explore the effects of POLR2J and vorinostat on the proliferation and migration of GBM cells. The highest overexpression of POLR2J, among all cancer types, was observed in GBM. Furthermore, high expression of POLR2J or its co-expressed genes predicted a poor outcome in GBM patients. DNA replication pathways were significantly enriched in the GBM clinical samples with high POLR2J expression, and POLR2J suppression inhibited proliferation and triggered cell cycle G1/S phase arrest in GBM cells. Moreover, POLR2J silencing activated the unfolded protein response (UPR) and significantly enhanced the anti-GBM activity of vorinostat by suppressing cell proliferation and inducing apoptosis. Additionally, POLR2J could interact with STAT3 to promote the metastatic potential of GBM cells. Our study identifies POLR2J as a novel oncogene in GBM progression and provides a promising strategy for the chemotherapeutic treatment of GBM.
ABSTRACT
BACKGROUND: According to the literatures, triacanthine is isolated from the leaves of Gleditsia triacanthos L. and acts as an anti-hypertensive agent, also cardiotonic, antispasmodic and a respiratory analeptic. The 5-fluorouracil (5-FU) is widely used to treat the patients of colorectal cancer (CRC), but the resistance to 5-FU treatment restricts the therapeutic efficacy of CRC patients. PURPOSE: This study aims to explore a novel therapeutics regimen overcoming CRC resistance to 5-FU. METHODS: The cell proliferation of CRC cells was determined by SRB and colony formation assay. Transwell and wound-healing assay were applied to explore the potential metastatic abilities of CRC cells. qRT-PCR and Western blot were performed to evaluate the level of indicated mRNAs and proteins respectively. Xenograft assay was used to explore the anti-CRC effect of triacanthine. RESULTS: Triacanthine statistically restrained CRC proliferation both in vitro and in vivo. Triacanthine induced cell cycle G1/G0 phase arrest in CRC cells. Meanwhile, triacanthine also inhibited the migrative and invasive abilities of CRC cells. A Venn diagram was generated showing that O-6-Methylguanine-DNA Methyltransferase (MGMT) might be a molecular target of triacanthine in treating CRC. Furthermore, triacanthine plus 5-FU significantly suppressed the cell proliferation of CRC cells compared with single agent treatment alone, and highly synergistic anti-cancer effects were scored when 5-FU was combined with triacanthine in CRC cells. In addition, triacanthine sensitized the anti-cancer activity of 5-FU via regulating Ribonucleotide Reductase Regulatory Subunit M2 (RRM2). MGMT or RRM2 might be novel biomarkers for evaluating the therapeutical efficiency of 5-FU in CRC patients. CONCLUSION: We firstly demonstrated triacanthine suppressed cell proliferation and metastasis abilities and found the novel molecular targets of triacanthine in CRC cells. This is the first study to evaluate the anti-cancer efficiency of triacanthine plus 5-FU. Our study has revealed triacanthine as a pertinent sensitizer to 5-FU, and provided novel strategies for predicting outcomes and reversing resistance of 5-FU therapy.
