IntroductionUEV1A encodes a ubiquitin-conjugating enzyme variant (Ubc13), which is required for Ubc13-catalyzed Lys63-linked polyubiquitination of target proteins and nuclear factor κB (NF-кB) activation. Previous reports have correlated the level of UEV1A expression with tumorigenesis; however, the detailed molecular events leading to tumors particularly breast cancer and metastasis are unclear. This study is to investigate roles of different UEV1 splicing variants, and its close homolog MMS2, in promoting tumorigenesis and metastasis in breast cancer cells.MethodsWe experimentally manipulated the UEV1 and MMS2 levels in MDA-MB-231 breast cancer cells and monitored their effects on cell invasion and migration, as well as tumor formation and metastasis in xenograft mice. The underlying molecular mechanisms leading to metastasis were also examined.ResultsIt was found that overexpression of UEV1A alone, but not UEV1C or MMS2, is sufficient to induce cell invasion in vitro and metastasis in vivo. This process is mediated by NF-κB activation and requires functional Ubc13. Our experimental data establish that among NF-κB target genes, UEV1A-regulated matrix metalloproteinase-1 (MMP1) expression plays a critical role in cell invasion and metastasis. Interestingly, experimental depletion of UEV1 in MDA-MB-231 cells reduces MMP1 expression and prevents tumor formation and metastasis in a xenograft mouse model, while overexpression of MMP1 overrides the metastasis effects in UEV1-depleted cells.ConclusionsThese results identify UEV1A as a potential therapeutic target in the treatment of metastasic breast cancers.

Cdc25A is a cell cycle-activating phosphatase, and its overexpression in breast cancers has been shown to correlate with poor prognosis. Most recent studies related to Cdc25A and tumor progression have focused on its role in regulating cell cycle progression. However, less is known about how Cdc25A modulates the metastasis of breast cancer cells. In this study, we revealed that Cdc25A enhances Foxo1 stability by dephosphorylating Cdk2, and Foxo1 was shown to directly regulate transcription of the metastatic factor MMP1. Further studies have shown that overexpression of Cdc25A in breast cancer cells enhances metastasis, whereas its downmodulation inhibits metastasis in mouse models, and the effects of Cdc25A on breast cancer cell metastasis are independent of cell proliferation and apoptosis. Furthermore, we have demonstrated that aberrant Cdc25A in breast cancer patient samples directly correlates with the metastatic phenotype. Further insights into this critical role of Cdc25A in the metastasis of breast cancer cells and the trial of an anti-Cdc25A strategy in mouse models may reveal its therapeutic potential in prevention and treatment of breast cancer cell dissemination.Breast cancer is one of the leading causes of morbidity and mortality in women worldwide (10,30,37). The majority of breast cancer deaths result from metastasis of breast cancer to other organs (14,16,36). Breast cancer metastasis has been shown to reduce the chances of long-term survival from 90% to around 5% (22). Therefore, insight into the molecular mechanisms underlying breast cancer invasion and metastasis would enable more effective treatment for breast cancer.Cdc25 phosphatases (Cdc25A, Cdc25B, and Cdc25C) promote cell cycle progression by dephosphorylating and activating cyclin-dependent kinases (Cdks) (38). Cdc25A activates cyclin E (A)-Cdk2 during G 1 through S and also seems to be involved in activation of Cdk1 at the G 2 /M boundary, and Cdc25A plays a nonredundant role in embryogenesis and oncogenesis (4, 12, 28). Cdc25B and Cdc25C, which collaborate for activation of cyclin B-Cdk1 at the G 2 /M boundary, are dispensable for checkpoint function (11,18,34). Among the Cdc25 family, Cdc25A is highlighted as an indispensable regulator of cell development and a driver of tumorigenesis (12,28,43,55). While the known role of Cdc25A in cell cycle progression and proliferation has been studied with respect to breast cancer pathogenesis (12,20,28,43), little is understood about whether and how Cdc25A affects the metastatic potential of breast cancer cells. Although epidemiologic studies have shown that most breast cancer patients (50 to 69%) have overexpressed Cdc25A and show poor prognosis (8, 25), not much is known about its association with breast cancer metastasis. In this study, we show that Cdc25A overexpression is correlated with the metastatic phenotype in breast cancer patient samples.Foxo1, one of the mammalian Forkhead transcription factors of class O (FoxO), is involved in a wide range of biological processes (2, 24). The Foxo1...

CD8+ memory T (TM) cells play a critical role in immune defense against infection. Two common γ-chain family cytokines, IL-2 and IL-7, although triggering the same mTORC1–S6K pathway, distinctly induce effector T (TE) cells and TM cells, respectively, but the underlying mechanism(s) remains elusive. In this study, we generated IL-7R-/and AMPKα1-knockout (KO)/OTI mice. By using genetic and pharmaceutical tools, we demonstrate that IL-7 deficiency represses expression of FOXO1, TCF1, p-AMPKα1 (T172), and p-ULK1 (S555) and abolishes T cell memory differentiation in IL-7R KO T cells after Listeria monocytogenesis rLmOVA infection. IL-2– and IL-7–stimulated strong and weak S6K (IL-2/S6Kstrong and IL-7/S6Kweak) signals control short-lived IL-7R−CD62L−KLRG1+ TE and long-term IL-7R+CD62L+KLRG1− TM cell formations, respectively. To assess underlying molecular pathway(s), we performed flow cytometry, Western blotting, confocal microscopy, and Seahorse assay analyses by using the IL-7/S6Kweak–stimulated TM (IL-7/TM) and the control IL-2/S6Kstrong–stimulated TE (IL-2/TE) cells. We determine that the IL-7/S6Kweak signal activates transcriptional FOXO1, TCF1, and Id3 and metabolic p-AMPKα1, p-ULK1, and ATG7 molecules in IL-7/TM cells. IL-7/TM cells upregulate IL-7R and CD62L, promote mitochondria biogenesis and fatty acid oxidation metabolism, and show long-term cell survival and functional recall responses. Interestingly, AMPKα1 deficiency abolishes the AMPKα1 but maintains the FOXO1 pathway and induces a metabolic switch from fatty acid oxidation to glycolysis in AMPKα1 KO IL-7/TM cells, leading to loss of cell survival and recall responses. Taken together, our data demonstrate that IL-7–stimulated weak strength of mTORC1–S6K signaling controls T cell memory via activation of transcriptional FOXO1–TCF1–Id3 and metabolic AMPKα1–ULK1–ATG7 pathways. This (to our knowledge) novel finding provides a new mechanism for a distinct IL-2/IL-7 stimulation model in T cell memory and greatly impacts vaccine development.