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Rationale : Cancer cells reprogram cellular metabolism to fulfill their needs for rapid growth and metastasis. However, the mechanism controlling this reprogramming is poorly understood. We searched for upregulated signaling in metastatic colorectal cancer and investigated the mechanism by which Glut3 promotes tumor metastasis. Methods : We compared RNA levels and glycolytic capacity in primary and metastatic colon cancer. The expression and association of Glut3 with clinical prognosis in colon cancer tissues was determined by immunohistochemistry. Glut3 gain-of-function and loss-of-function were established using colon cancer HCT116, HT29, and metastatic 116-LM cells, and tumor invasiveness and stemness properties were evaluated. Metabolomic profiles were analyzed by GC/MS and CE-TOF/MS. The metastatic burden in mice fed a high-fat sucrose diet was assessed by intravenous inoculation with Glut3 knockdown 116-LM cells. Results : Upregulation of glycolytic genes and glycolytic capacity was detected in metastatic colorectal cancer cells. Specifically, Glut3 overexpression was associated with metastasis and poor survival in colorectal cancer patients. Mechanistically, Glut3 promoted invasiveness and stemness in a Yes-associated protein (YAP)-dependent manner. Activation of YAP in turn transactivated Glut3 and regulated a group of glycolytic genes. Interestingly, the expression and phosphorylation of PKM2 were concomitantly upregulated in metastatic colorectal cancer, and it was found to interact with YAP and enhance the expression of Glut3. Importantly, a high-fat high-sucrose diet promoted tumor metastasis, whereas the inhibition of either Glut3 or YAP effectively reduced the metastatic burden. Conclusion : Activation of the Glut3-YAP signaling pathway acts as a master activator to reprogram cancer metabolism and thereby promotes metastasis. Our findings reveal the importance of metabolic reprogramming in supporting cancer metastasis as well as possible therapeutic targets.

The tumor microenvironment plays an important role in tumor initiation and progression. It is well documented that nicotine participates in cigarette smoking-related malignancies. Previous studies focused on the effects of nicotine on tumor cells; however, the role of the microenvironment in nicotine-mediated tumorigenesis is poorly understood. Herein, we investigated the effect and molecular mechanism of nicotine on fibroblasts and its contribution to breast cancer. We found that nicotine induced the epithelial-mesenchymal transition (EMT) of breast cancer cells and promoted activation of fibroblasts. Interestingly, conditioned medium from nicotine-activated fibroblasts (Nic-CM) had a greater impact on promoting the EMT and migratory capability toward cancer cells than did treatment with nicotine alone. Production of connective tissue growth factor (CTGF) and transforming growth factor (TGF)-β by nicotine-treated fibroblasts was demonstrated to be crucial for promoting the EMT and cancer cell migration, and blocking of CTGF and TGF-β in Nic-CM-suppressed tumor motility. Moreover, nicotine induced expressions of CTGF, and TGF-β in fibroblasts as identified through α7 nicotinic acetylcholine receptor (nAChR)-dependent activation of the AKT/TAZ signaling mechanism. Together, our data showed for the first time that activation of fibroblasts is largely responsible for accelerating smoking-mediated breast cancer progression.

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Infection of the alveolar epithelium constitutes a bottleneck in the progression of COVID-19 to SARS presumably due to the paucity of viral entry receptors in alveolar epithelial type 1 and 2 cells. We have found that the male alveolar epithelial cells express twice as many ACE2 and TMPRSS2 entry receptors as the female ones. Intriguingly, IFN and TNF-α signaling are preferentially active in male alveolar cells and induce binding of the cognate transcription factors to the promoters and lung-active enhancers of ACE2 and TMPRSS2. Cotreatment with IFN-I and III dramatically increases expression of the receptors and viral entry in alveolar epithelial cells. TNFα and IFN-II, typically overproduced during the cytokine storm, similarly collaborate to induce these events. Whereas JAK inhibitors suppress viral entry induced by IFN-I/III, simultaneous inhibition of IKK/NF-κB is necessary to block viral entry induced by TNFα and IFN II. In addition to explaining the increased incidence of SARS in males, these findings indicate that SARS-Cov-2 hijacks epithelial immune signaling to promote infection of the alveolar epithelium and suggest that JAK inhibitors, singly and in combination with NF-KB inhibitors, may exhibit efficacy in preventing or treating COVID-19 SARS.