NUCKS1 promotes the progression of colorectal cancer via activating PI3K/AKT/mTOR signaling pathway.

Nuclear ubiquitous casein and cyclin-dependent kinase substrate 1 (NUCKS1) is highly expressed in a variety of malignant tumors and functions as an oncogene; however, its role in colorectal cancer (CRC) remains unclear. We aimed to explore the function and regulatory mechanisms of NUCKS1 and potential therapeutic agents targeting NUCKS1 in CRC. We knocked down and overexpressed NUCKS1 in CRC cells and explored its effects in vitro and in vivo. Flow cytometry, CCK-8, Western blotting, colony formation, immunohistochemistry, in vivo tumorigenic, and transmission electron microscopy analyses were performed to determine the effects of NUCKS1 on CRC cell function. LY294002 was used to examine the mechanism of NUCKS1 expression in CRC cells. Potential therapeutic agents for NUCKS1-high CRC patients were analyzed using the CTRP and PRISM datasets, and the function of selected agents was determined by CCK-8 and Western blotting. We revealed that NUCKS1 was highly expressed in CRC tissues and clinically correlated with poor prognosis in CRC patients. NUCKS1 knockdown induces cell cycle arrest, inhibits CRC cell proliferation, and promotes apoptosis and autophagy. These results were reversed when NUCKS1 was overexpressed. Mechanistically, NUCKS1 exerts a cancer-promoting function by activating the PI3K/AKT/mTOR signaling pathway. This was reversed when LY294002 was used to inhibit the PI3K/AKT pathway. Furthermore, we determined that mitoxantrone exhibited high drug sensitivity in NUCKS1-overexpressing CRC cells. This work demonstrated NUCKS1 plays a crucial role in CRC progression via the PI3K/AKT/mTOR signaling pathway. Additionally, mitoxantrone may be a potential therapeutic agent for CRC treatment. Therefore, NUCKS1 represents a promising anti-tumor therapeutic target.

Lung Cancer Cells-Controlled Dkk-1 Production in Brain Metastatic Cascade Drive Microglia to Acquire a Pro-tumorigenic Phenotype.

OBJECTIVES: Organotropism is primarily determined by tumor-derived exosomes. To date, the role of lung cancer cells-derived exosomes underlying the pre-metastatic niche formation is unclear. MATERIALS AND METHODS: The animal models of retro-orbital and intra-ventricular injection were constructed to administrate lung cancer cells-derived exosomes. Cytokine array was used to screen the cytokines released from brain endothelium after internalization of lung cancer cells-derived exosomes. The cellular co-culture system was established to mimic microglia-vascular niche contained lung cancer cells-derived exosomes. The levels of Dkk-1 and the activities of microglia were analyzed by qRT-PCR, western blot and immunofluorescence. In vivo selections of highly brain metastatic cells were performed to analyze the direct interaction of lung cancer cells with microglia. RESULTS: Animal studies demonstrated that there was a suppressive signal transferred from brain endothelium to microglia after internalization of lung cancer cells-derived exosomes into brain endothelium, which caused an absolutely less M1 phenotypic microglia and a relatively more M2 phenotypic microglia. Further results indicated that lung cancer cells-derived exosomes induced a release of endogenous Dkk-1 from brain endothelium, which rendered microglia to acquire a pro-tumorigenic feature in pre-metastatic niche. Subsequently, the declines of Dkk-1 in metastatic lung cancer cells removed the suppression on microglia and enhanced microglial activation in metastatic niche. CONCLUSION: Our findings shed a new light on the synergistic reaction of the different cells in "neurovascular units" toward the metastatic messages from lung cancer cells and provided a potential therapeutic pathway for lung cancer metastasis to brain.

Brain microvascular endothelial cell exosome-mediated S100A16 up-regulation confers small-cell lung cancer cell survival in brain.

Small cell lung cancer (SCLC) is the most aggressive histologic subtype of lung cancer, with a strong predilection for early brain metastases. Despite efforts and advances in new therapeutics for SCLC, the prognosis of patients with SCLC with brain metastases is consistently poor. Therefore, a better understanding of the mechanisms of SCLC brain metastasis is important in improving current treatments. In this study, elevated S100A16 levels were associated with SCLC brain metastases, which was a possible secondary event arising from the brain metastatic microenvironment. Using an in vitro cell coculture system, we found that the coculturing of SCLC cells with human brain microvascular endothelial cells (HBMECs) led to an increased expression of S100A16 in SCLC cells. Conversely, treatment of HBMECs with GW4869, an inhibitor of exosome release, significantly blocked this effect in the cocultured SCLC cells. Alternatively, the results from Western blot analyses and immunofluorescence indicated that the HBMEC exosomes purified by ultracentrifugation also induced the elevation and translocation from the cytoplasm to the nucleus of S100A16 in the recipient SCLC cells. The inhibition experiments demonstrated that elevated S100A16 contributed a benefit of HBMEC exosomes for the survival of the recipient SCLC cells under stress. Moreover, the elevation of S100A16 in SCLC cells prevented the loss of mitochondrial membrane potential (Δψm) and enhanced resistance to apoptosis under stressful conditions, which were determined by Annexin V/propidium iodide and JC-1 assay. Further results showed that the S100A16-mediated protective effect was caused by the presence of an important element in Δψm, prohibitin (PHB)-1, a protein in the mitochondrial inner membrane. Conversely, the delivery of PHB-1 siRNAs into S100A16 overexpressing SCLC cells weakened these protective effects. Our findings suggest that elevated S100A16 plays an active role in facilitating the survival of SCLC cells through modulating the mitochondrial function, identifying S100A16 as an important potential target in SCLC brain metastasis.-Xu, Z.-H., Miao, Z.-W., Jiang, Q.-Z., Gan, D.-X., Wei, X.-G., Xue, X.-Z., Li, J.-Q., Zheng, F., Qin, X.-X., Fang, W.-G., Chen, Y.-H., Li. B. Brain microvascular endothelial cell exosome-mediated S100A16 up-regulation confers small cell lung cancer cell survival in brain.