In 2008 we published the first set of guidelines for standardizing research in autophagy. Since then, research on this topic has continued to accelerate, and many new scientists have entered the field. Our knowledge base and relevant new technologies have also been expanding. Accordingly, it is important to update these guidelines for monitoring autophagy in different organisms. Various reviews have described the range of assays that have been used for this purpose. Nevertheless, there continues to be confusion regarding acceptable methods to measure autophagy, especially in multicellular eukaryotes. A key point that needs to be emphasized is that there is a difference between measurements that monitor the numbers or volume of autophagic elements (e.g., autophagosomes or autolysosomes) at any stage of the autophagic process vs. those that measure flux through the autophagy pathway (i.e., the complete process); thus, a block in macroautophagy that results in autophagosome accumulation needs to be differentiated from stimuli that result in increased autophagic activity, defined as increased autophagy induction coupled with increased delivery to, and degradation within, lysosomes (in most higher eukaryotes and some protists such as Dictyostelium) or the vacuole (in plants and fungi). In other words, it is especially important that investigators new to the field understand that the appearance of more autophagosomes does not necessarily equate with more autophagy. In fact, in many cases, autophagosomes accumulate because of a block in trafficking to lysosomes without a concomitant change in autophagosome biogenesis, whereas an increase in autolysosomes may reflect a reduction in degradative activity. Here, we present a set of guidelines for the selection and interpretation of methods for use by investigators who aim to examine macroautophagy and related processes, as well as for reviewers who need to provide realistic and reasonable critiques of papers that are focused on these processes. These guidelines are not meant to be a formulaic set of rules, because the appropriate assays depend in part on the question being asked and the system being used. In addition, we emphasize that no individual assay is guaranteed to be the most appropriate one in every situation, and we strongly recommend the use of multiple assays to monitor autophagy. In these guidelines, we consider these various methods of assessing autophagy and what information can, or cannot, be obtained from them. Finally, by discussing the merits and limits of particular autophagy assays, we hope to encourage technical innovation in the field

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Both stem cells and cancer cells are thought to be capable of unlimited proliferation. Paradoxically, however, some cancers seem to contain stem-like cells (cancer stem cells). To help resolve this paradox, we investigated whether established malignant cell lines, which have been maintained for years in culture, contain a subpopulation of stem cells. In this article, we show that many cancer cell lines contain a small side population (SP), which, in many normal tissues, is thought to contain the stem cells of the tissue. We demonstrate that in the absence of serum the combination of basic fibroblast growth factor and platelet-derived growth factor maintains SP cells in the C6 glioma cell line. Moreover, we show that C6 SP cells, but not non-SP cells, can generate both SP and non-SP cells in culture and are largely responsible for the in vivo malignancy of this cell line. Finally, we provide evidence that C6 SP cells can produce both neurons and glial cells in vitro and in vivo. We propose that many cancer cell lines contain a minor subpopulation of stem cells that is enriched in an SP, can be maintained indefinitely in culture, and is crucial for their malignancy.

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The study shows constitutive activation of the Notch pathway in various types of malignancies. However, it remains unclear how the Notch pathway is involved in the pathogenesis of osteosarcoma. We investigated the expression of the Notch pathway molecules in osteosarcoma biopsy specimens and examined the effect of Notch pathway inhibition. Real-time PCR revealed overexpression of Notch2, Jagged1, HEY1, and HEY2. On the other hand, Notch1 and DLL1 were downregulated in biopsy specimens. Notch pathway inhibition using g-secretase inhibitor and CBF1 siRNA slowed the growth of osteosarcomas in vitro. In addition, g-secretase inhibitortreated xenograft models exhibited significantly slower osteosarcoma growth. Cell cycle analysis revealed that g-secretase inhibitor promoted G1 arrest. Real-time PCR and western blot revealed that g-secretase inhibitor reduced the expression of accelerators of the cell cycle, including cyclin D1, cyclin E1, E2, and SKP2. On the other hand, p21cip1 protein, a cell cycle suppressor, was upregulated by g-secretase inhibitor treatment. These findings suggest that inhibition of Notch pathway suppresses osteosarcoma growth by regulation of cell cycle regulator expression and that the inactivation of the Notch pathway may be a useful approach to the treatment of patients with osteosarcoma.

BackgroundThe Hedgehog signaling pathway functions as an organizer in embryonic development. Recent studies have demonstrated constitutive activation of Hedgehog pathway in various types of malignancies. However, it remains unclear how Hedgehog pathway is involved in the pathogenesis of osteosarcoma. To explore the involvement of aberrant Hedgehog pathway in the pathogenesis of osteosarcoma, we investigated the expression and activation of Hedgehog pathway in osteosarcoma and examined the effect of SMOOTHENED (SMO) inhibition.ResultsTo evaluate the expression of genes of Hedgehog pathway, we performed real-time PCR and immunohistochemistry using osteosarcoma cell lines and osteosarcoma biopsy specimens. To evaluate the effect of SMO inhibition, we did cell viability, colony formation, cell cycle in vitro and xenograft model in vivo. Real-time PCR revealed that osteosarcoma cell lines over-expressed Sonic hedgehog, Indian hedgehog, PTCH1, SMO, and GLI. Real-time PCR revealed over-expression of SMO, PTCH1, and GLI2 in osteosarcoma biopsy specimens. These findings showed that Hedgehog pathway is activated in osteosarcomas. Inhibition of SMO by cyclopamine, a specific inhibitor of SMO, slowed the growth of osteosarcoma in vitro. Cell cycle analysis revealed that cyclopamine promoted G1 arrest. Cyclopamine reduced the expression of accelerators of the cell cycle including cyclin D1, cyclin E1, SKP2, and pRb. On the other hand, p21cip1 wprotein was up-regulated by cyclopamine treatment. In addition, knockdown of SMO by SMO shRNA prevents osteosarcoma growth in vitro and in vivo.ConclusionsThese findings suggest that inactivation of SMO may be a useful approach to the treatment of patients with osteosarcoma.

Neural stem cell (NSC) differentiation is precisely controlled by a network of transcription factors, which themselves are regulated by extracellular signals (Bertrand et al., 2002; Shirasakiand and Pfaff, 2002). One way that the activity of such transcription factors is controlled is by the regulation of their movement between the cytosol and nucleus (Vandromme et al., 1996. Lei and Silver, 2002). Here we show that the basic helix–loop–helix transcription factor OLIG2, which has been shown to be required for motor neuron and oligodendrocyte development, is found in the cytoplasm, but not the nucleus, of astrocytes in culture and of a subset of astrocytes in the subventricular zone. We demonstrate that the accumulation of OLIG2 in the nucleus of NSCs blocks the CNTF-induced astrocyte differentiation and that the translocation of OLIG2 to the cytoplasm is promoted by activated AKT. We propose that the AKT-stimulated export of OLIG2 from the nucleus of NSCs is essential for the astrocyte differentiation.

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