To determine the mechanism responsible for the in vivo production of angiostatin that inhibits growth and metastasis in Lewis lung carcinoma (3LL), we implanted 3LL variant cells into the subcutis of syngeneic C57BL/6 mice. The tumors were infiltrated by macrophages and expressed high levels of steady-state mRNA for metalloelastase (MME). Successive passages (more than three) of cultures established from the tumors resulted in complete depletion of macrophages; steady-state MME mRNA, elastinolytic activity, and production of angiostatin (in the presence of plasminogen) were correspondingly reduced. Coculture of macrophages with either 3LL cells or their conditioned media containing granulocyte-macrophage colony-stimulating factor resulted in secretion of MME and production of angiostatin by the macrophages, suggesting that angiostatin is produced by tumor-infiltrating macrophages whose MME expression is stimulated by tumor cell-derived granulocyte-macrophage colony-stimulating factor.

The INO80 (inositol requiring mutant 80) chromatin remodeling complex plays important roles in transcriptional regulation and DNA replication and repair, and consists of several functional protein subunits, including the critical Ino80 ATPase catalytic subunit. While the function of INO80 has been studied in yeast and mammalian cell lines, we do not know how mIno80 contributes to the maintenance of genome stability to prevent cancer development in mice. Here, we use a conditional knockout approach to explore the cellular and organismal functions of mIno80. Deletion of mIno80 results in profound cellular proliferative defects and activation of p21-dependent cellular senescence. While mIno80 is required for efficient repair of DNA double strand breaks, its depletion did not impact upon the formation of γ-H2AX and 53BP1 DNA damage foci, or the activation of the ATM-CHK2-dependent DNA damage response. mIno80 deletion inhibited the generation of single-strand DNA, resulting in defects in homology-directed DNA repair (HDR) at telomeres. Fragile telomeres were prominent in mIno80 ∆/∆ MEFs, suggesting that chromatin remodeling is required for efficient telomere replication. mIno80 −/− mouse embryos die early during embryogenesis, while conditional deletion of mIno80 in adult mice results in weight loss and premature death. In a p53 −/− tumorprone background, mIno80 haploinsufficiency favored the development of sarcomas. Our studies suggest that the mIno80 chromatin remodeling complex plays important roles in telomere replication, HDR-mediated repair of dysfunctional telomeres, and maintenance of genome stability.

This case study of an online graduate course determines the message characteristics of the instructor, volunteer teaching assistants, and students in online discussions, and proposes a mentoring, coaching, and facilitating model for online discussions. The researchers developed a coding system based on the literature of mentoring, coaching, and facilitating to identify the characteristics of conference discussion messages. The instructor fostered the development of volunteer teaching assistants into coaches and of student discussion facilitators into facilitators of learning. The proposed constructivist model fosters active learning, provides scaffolding for students to become facilitators of learning, and suggests creative ways for online instructors to manage different types of teaching responsibilities. Recommendations for further research are included.

Molecular targeting for apoptosis induction is being developed for better treatment of cancer. Downregulation of 15-lipoxygenase-1 (15-LOX-1) is linked to colorectal tumorigenesis. Re-expression of 15-LOX-1 in cancer cells by pharmaceutical agents induces apoptosis. Antitumorigenic agents can also induce apoptosis via other molecular targets. Whether restoring 15-LOX-1 expression in cancer cells is therapeutically sufficient to inhibit colonic tumorigenesis remains unknown. We tested this question using an adenoviral delivery system to express 15-LOX-1 in in vitro and in vivo models of colon cancer. We found that (i) the adenoviral vector 5/3 fiber modification enhanced 15-LOX-1 gene transduction in various colorectal cancer cell lines, (ii) the adenoviral vector delivery restored 15-LOX-1 expression and enzymatic activity to therapeutic levels in colon cancer cell lines, and (iii) 15-LOX-1 expression downregulated the expression of the antiapoptotic proteins X-linked inhibitor of apoptosis protein (XIAP) and BcL-XL, activated caspase-3, triggered apoptosis, and inhibited cancer cell survival in vitro and the growth of colon cancer xenografts in vivo. Thus, selective molecular targeting of 15-LOX-1 expression is sufficient to re-establish apoptosis in colon cancer cells and inhibit tumorigenesis. These data provide the rationale for further development of therapeutic strategies to target 15-LOX-1 molecularly for treating colonic tumorigenesis.

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