B7-H4, a member of B7 family, is a transmembrane protein and inhibits T-cells immunity. However, in a variety of tumor cells, B7-H4 was detected predominantly in intracellular compartments with unknown mechanism and functions. In this study, we analyzed B7-H4 expression and subcellular distribution by immunohistochemistry in renal cell carcinoma (RCC) tissues. B7-H4 protein was detected on the membrane, in the cytosol and/or in the nucleus in tumor tissues. The membrane and nuclear expression of B7-H4 was significantly correlated with the tumor stages of RCC. Moreover, the membrane localization of B7-H4 was inversely correlated with the intensity of tumor infiltrates lymphocyte (TILs), whereas no association was observed between nuclear expression of B7-H4 and the density of TILs status. We further identified that B7-H4 is a cytoplasmic-nuclear shuttling protein containing a functional nuclear localization sequence (NLS) motif. A point mutation of B7-H4 NLS motif blocked the leptomycin B -induced nuclear accumulation of B7-H4. HEK293 cells stably expressing B7-H4 NLS mutant exhibited more potent inhibition in T-cell proliferation and cytokine production through increasing its surface expression compared with wild-type B7-H4 transfected cells owing to their increased surface expression. Most importantly, overexpression of wild-type B7-H4 in HEK293 cells enhanced tumor cell proliferation in vitro and tumorigenicity in vivo, promoted G1/S phase transition. The regulation of cell cycle by wild-type B7-H4 was partialy due to upregulation of Cyclin D 1 and Cyclin E. A mutation of B7-H4 NLS motif abolished the B7-H4-mediated cell proliferation and cell cycle regulation. Furthermore, B7-H4 wild-type confers chemoresistance activity to RCC cell lines including Caki-1 and ACHN. Our study provides a new insight into the functional implication of B7-H4 in its subcellular localization.

In mammals, embryonic development are highly regulated morphogenetic processes that are tightly controlled by genetic elements. Failure of any one of these processes can result in embryonic malformation. The lysyl oxidase (LOX) family genes are closely related to human diseases. In this study, we investigated the essential role of lysyl oxidase-like 3 (LOXL3), a member of the LOX family, in embryonic development. Mice lacking LOXL3 exhibited perinatal lethality, and the deletion of the Loxl3 gene led to impaired development of the palate shelves, abnormalities in the cartilage primordia of the thoracic vertebrae and mild alveolar shrinkage. We found that the obvious decrease of collagen cross-links in palate and spine that was induced by the lack of LOXL3 resulted in cleft palate and spinal deformity. Thus, we provide critical in vivo evidence that LOXL3 is indispensable for mouse palatogenesis and vertebral column development. The Loxl3 gene may be a candidate disease gene resulting in cleft palate and spinal deformity.

Osteosarcoma (OS) is the most common malignant bone tumor in children and young adults, the early symptoms and signs of which are non-specific. The discovery of microRNAs (miRNAs) provides a new avenue for the early diagnosis and treatment of OS. miR-126 has been reported to be highly expressed in vascularized tissues, and is recently widely studied in cancers. Herein, we explored the expression and significance of miR-126 in OS. Using TaqMan RT-PCR analysis, we analyzed the expression of miR-126 in 32 paired OS tumor tissues and 4 OS cell lines and found that miR-126 was consistently under-expressed in OS tissues and cell lines compared with normal bone tissues and normal osteoblast cells (NHOst), respectively. As miR-126 is significantly decreased in OS tissues and cell lines, we sought to compensate for its loss through exogenous transfection into MG-63 cells with a miR-126 mimic. Ectopic expression of miR-126 inhibited cell proliferation, migration and invasion, and induced apoptosis of MG-63 cells. Moreover, bioinformatic prediction suggested that the sex-determining region Y-box 2 (Sox2) is a target gene of miR-126. Using mRNA and protein expression analysis, luciferase assays and rescue assays, we demonstrate that restored expression of Sox2 dampened miR-126-mediated suppression of tumor progression, which suggests the important role of miR-126/Sox2 interaction in tumor progression. Taken together, our data indicate that miR-126 functions as a tumor suppressor in OS, which exerts its activity by suppressing the expression of Sox2.

Although microRNAs (miRNAs or miRs) are able to function as oncogenes or tumor suppressors, the role of miR-326 in regulating human cervical cancer cells remains unclear. In the present study, the expression of miR-326 was identified to be downregulated in cervical cancer cell lines and primary tumor samples, and the overexpression of miR-326 decreased cell proliferation, migration and invasion in cervical cell lines. Bioinformatics prediction and experimental validation results revealed that the function of miR-326 was achieved by targeting and repressing ETS domain-containing protein Elk-1 (ELK1) expression. ELK1 was targeted directly by miR-326, which was downregulated in human cervical cancer tissues compared with that in adjacent normal tissues. The results of the present study suggest that miR-326, a potential tumor suppressor, may be used in the treatment of cervical cancer.

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