Infection of cells with replication deficient adenovirus induces cell cycle alterations and leads to downregulation of E2F-1

IGFBP3 inhibits tumor growth and invasion of lung cancer cells and is associated with improved survival in lung cancer patients

The insulin-like growth factor (IGF)-pathway is involved in tumor cell proliferation, metastasis, and survival. We aimed to find out what effects IGF binding protein 3 (IGFBP3) exerted on H1299 lung cancer (LC) cells in terms of tumor growth and invasion and whether IGFBP3 was associated with clinical and pathological parameters in a prospective cohort of LC patients. H1299 cells were transfected with an IGFBP3-expressing vector. Its influence on apoptosis induction via flow cytometry annexin V FITC assay, cell proliferation in 2D and 3D cell culture, and invasion were examined. Expression of several matrix metalloproteinases (MMPs) and inhibitors (TIMP-1) were also investigated in IGFBP3-transfected LC cells. Further, data on LC patients (n = 131), tumor characteristics, and survival were prospectively collected and correlated with IGFBP3 plasma levels. IGFBP3 did not influence apoptosis induction and 2D cell proliferation. However, both spheroid growth (3D proliferation) and invasion of IGFBP3-transfected cells planted in an extracellular matrix-based gel were significantly inhibited. IGFBP3 inhibited MMP-1 release, and the total MMP activity. In LC patients, higher IGFBP3 plasma levels correlated with both lower clinical tumor stage, grading, Ki-67 staining, and the absence of necrosis (P < 0.05, respectively). Increased IGFBP3 plasma levels were associated with improved overall survival (hazard ratio 0.37, P = 0.01). In conclusion, overexpressed IGFBP3 in a LC cell line inhibited tumor growth and invasion. Translating from bench to bedside, investigation of clinicopathological parameters confirmed these experimental results showing that higher IGFBP3 plasma levels were associated with less aggressive tumor growth, reduced tumor spread, and improved survival of LC patients.

Identification and isolation of embryonic stem cell-derived target cells by adenoviral conditional targeting

The technical limitations of isolating target cells have restricted the utility of pluripotent embryonic stem (ES) cells. For example, early cardiac (i.e., precontractile) cells have not been isolated from ES cells. Here, we find that direct expression of reporter genes under cell-specific promoters-the currently available strategy for isolating cells lacking cell-specific surface markers-is ineffective for isolating progenitor cells. This was due to the weak activity of cell-specific promoters, particularly in ES cells at early stages. We show that adenoviral conditional targeting efficiently isolates viable ES cell-derived target cells without harmful effects. In this strategy, we employ the alpha-myosin heavy chain and Nkx2.5 promoter to visualize and purify efficiently differentiated and primitive cells of the cardiac lineage, respectively. While the former cells predominantly expressed sarcomeric proteins and maintained contractile function, the latter demonstrated neither of these features, but rather exhibited expression patterns characteristic of a mixture of primitive cells and cardiomyocytes. Interestingly, smooth muscle actin was predominantly expressed in the latter cells, and both functionally known and unknown genes were systematically identified, demonstrating the benefits of this system. Thus, our method facilitates molecular and cellular studies of development and ES cell-derived cell therapy.