Side population (SP) cells within tumors are a small fraction of cancer cells with stem-like properties that can be identified by flow cytometry analysis based on their high ability to export certain compounds such as Hoechst 33342 and chemotherapeutic agents. The existence of stem-like SP cells in tumors is considered as a key factor contributing to drug resistance, and presents a major challenge in cancer treatment. Although it has been recognized for some time that tumor tissue niches may significantly affect cancer stem cells (CSCs), the role of key nutrients such as glucose in the microenvironment in affecting stem-like cancer cells and their metabolism largely remains elusive. Here we report that SP cells isolated from human cancer cells exhibit higher glycolytic activity compared to non-SP cells. Glucose in the culture environment exerts a profound effect on SP cells as evidenced by its ability to induce a significant increase in the percentage of SP cells in the overall cancer cell population, and glucose starvation causes a rapid depletion of SP cells. Mechanistically, glucose upregulates the SP fraction through ATP-mediated suppression of AMPK and activation of the Akt pathway, leading to elevated expression of the ATP-dependent efflux pump ABCG2. Importantly, inhibition of glycolysis by 3-BrOP significantly reduces SP cells in vitro and impairs their ability to form tumors in vivo. Our data suggest that glucose is an essential regulator of SP cells mediated by the Akt pathway, and targeting glycolysis may eliminate the drug-resistant SP cells with potentially significant benefits in cancer treatment. Accumulating evidence suggests that tumors of various tissue origins, including the brain, breast, and lung, contain a small subpopulation of special cells with stem-like properties, often referred to as cancer stem cells (CSCs) or tumor-initiating cells. [1][2][3][4][5][6][7] In addition to the ability of CSCs to self-renew and initiate tumor formation, one important biochemical feature of CSCs is their ability to export certain toxic compounds and resistance to many chemotherapeutic agents due in part to their high expression of ATP-dependent efflux pump ABCG2, their increased DNA repair capacity, and activation of survival pathways. [8][9][10] The increase in expression of ABCG2 also confers CSCs the ability to effectively export the DNA-binding dye Hoechst 33342 out of the cells, leading to a low retention of the fluorescent signal in these cells, which appear at the low-left corner in flow cytometry analysis and thus are known as 'side population' or SP cells. 2,11 As SP cells can be readily identified by flow cytometry in a quantitative manner, the measurement of SP cells has been widely used as a quantitative assay for the relative number (%) of stem-like cancer cells in the bulk of the overall cancer cell population. Importantly, as this assay is functionally based on the ability of SP cells to export Hoechst 33342 and certain toxic compounds, it is also a quantitative analysis of the subpopulatio...

Background: The prognosis of human astrocytoma is poor, and the molecular alterations underlying its pathogenesis still needed to be elucidated. Nucleolar and spindle associated protein 1 (NUSAP1) was observed in several types of cancers, but its role in astrocytoma remained unknown. Methods:The expression of NUSAP1 in astrocytoma cell lines and tissues were measured with western blotting and Real-Time PCR. Two hundred and twenty-one astrocytoma tissue samples were analyzed by immunochemistry to demonstrate the correlation between the NUSAP1 expression and clinicopathological characteristics. 3-(4,5-dimethylthiazol-2-yl) 2,5-diphenyltetrazolium bromide (MTT) assay, colony formation, transwell matrix penetration assay, wound healing assay and anchorage-independent growth assay were used to investigate the biological effect of NUSAP1 in astrocytoma. An intracranial brain xenograft tumor model was used to confirm the oncogenic role of NUSAP1 in human astrocytoma. Luciferase reporter assay was used to investigate the effect of NUSAP1 on Hedgehog signaling pathway.Results: NUSAP1 was markedly overexpressed in astrocytoma cell lines and tissues compared with normal astrocytes and brain tissues. NUSAP1 was found to be overexpressed in 152 of 221 (68.78%) astrocytoma tissues, and was significantly correlated to poor survival. Further, ectopic expression or knockdown of NUSAP1 significantly promoted or inhibited, respectively, the invasive ability of astrocytoma cells. Moreover, intracranial xenografts of astrocytoma cells engineered to express NUSAP1 were highly invasive compared with the parental cells. With regard to its molecular mechanism, upregulation of NUSAP1 in astrocytoma cells promoted the nuclear translocation of GLI family zinc finger 1 (GLI1) and upregulated the downstream genes of the Hedgehog pathway.Conclusion: These findings indicate that NUSAP1 contributes to the progression of astrocytoma by enhancing tumor cell invasiveness via activation of the Hedgehog signaling pathway, and that NUSAP1 might be a potential prognostic biomarker as well as a target in astrocytoma.

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Long noncoding RNAs (lncRNAs), once considered to be nonfunctional relics of evolution, are emerging as essential genes in tumor progression. However, the function and underlying mechanisms of lncRNAs in glioma remain unclear. This study aimed to investigate the role of LINC00998 in glioma progression. Through screening using TCGA database, we found that LINC00998 was downregulated in glioblastoma tissues and that low expression of LINC00998 was associated with poor prognosis. Overexpression of LINC00998 inhibited glioma cell proliferation in vitro and in vivo and blocked the G1/S cell cycle transition, which exerted a tumor-suppressive effect on glioma progression. Mechanistically, RNA pull-down and mass spectrometry results showed an interaction between LINC00998 and CBX3. IP assays demonstrated that LINC00998 could stabilize CBX3 and prevent its ubiquitination degradation. GSEA indicated that LINC00998 could regulate the c-Met/Akt/mTOR signaling pathway, which was further confirmed by a rescue assay using siRNA-mediated knockdown of CBX3 and the Akt inhibitor MK2206. In addition, dual-luciferase assays showed that miR-34c-5p could directly bind to LINC00998 and downregulate its expression. Our results identified LINC00998 as a novel tumor suppressor in glioma, and LINC00998 could be a novel prognostic biomarker, providing a strategy for precision therapy in glioma patients.

In conclusion, we found that several radiographic and sonographic parameters were associated with the prognosis of patients with NEC. The AUS model based on the logistic regression analysis was significant superior to the AR model in the prognostic prediction of NEC.