4 research outputs found
The formation of vault-tubes: a dynamic interaction between vaults and vault PARP
Vaults are barrel-shaped cytoplasmic ribonucleoprotein particles that are
composed of a major vault protein (MVP), two minor vault proteins
[telomerase-associated protein 1 (TEP1), vault poly(ADP-ribose) polymerase
(VPARP)] and small untranslated RNA molecules. Not all expressed TEP1 and
VPARP in cells is bound to vaults. TEP1 is known to associate with the
telomerase complex, whereas VPARP is also present in the nuclear matrix
and in cytoplasmic clusters (VPARP-rods). We examined the subcellular
localization and the dynamics of the vault complex in a non-small cell
lung cancer cell line expressing MVP tagged with green fluorescent
protein. Using quantitative fluorescence recovery after photobleaching
(FRAP) it was shown that vaults move temperature independently by
diffusion. However, incubation at room temperature (21 degrees C) resulted
in the formation of distinct tube-like structures in the cytoplasm.
Raising the temperature could reverse this process. When the vault-tubes
were formed, there were fewer or no VPARP-rods present in the cytoplasm,
suggesting an incorporation of the VPARP into the vault-tubes. MVP
molecules have to interact with each other via their coiled-coil domain in
order to form vault-tubes. Furthermore, the stability of microtubules
influenced the efficiency of vault-tube formation at 21 degrees C. The
dynamics and structure of the tubes were examined using confocal
microscopy. Our data indicate a direct and dynamic relationship between
vaults and VPARP, providing further clues to unravel the function of
vaults
Disruption of the murine major vault protein (MVP/LRP) gene does not induce hypersensitivity to cytostatics
Vaults are ribonucleoprotein particles with a distinct structure and a
high degree of conservation between species. Although no function has been
assigned to the complex yet, there is some evidence for a role of vaults
in multidrug resistance. To confirm a direct relation between vaults and
multidrug resistance, and to investigate other possible functions of
vaults, we have generated a major vault protein (MVP/lung
resistance-related protein) knockout mouse model. The MVP(-/-) mice are
viable, healthy, and show no obvious abnormalities. We investigated the
sensitivity of MVP(-/-) embryonic stem cells and bone marrow cells derived
from the MVP-deficient mice to various cytostatic agents with different
mechanisms of action. Neither the MVP(-/-) embryonic stem cells nor the
MVP(-/-) bone marrow cells showed an increased sensitivity to any of the
drugs examined, as compared with wild-type cells. Furthermore, the
activities of the ABC-transporters P-glycoprotein, multidrug
resistance-associated protein and breast cancer resistance protein were
unaltered on MVP deletion in these cells. In addition, MVP wild-type and
deficient mice were treated with the anthracycline doxorubicin. Both
groups of mice responded similarly to the doxorubicin treatment. Our
results suggest that MVP/vaults are not directly involved in the
resistance to cytostatic agents
Defining the Critical Hurdles in Cancer Immunotherapy
ABSTRACT: Scientific discoveries that provide strong evidence of antitumor effects in preclinical models often encounter significant delays before being tested in patients with cancer. While some of these delays have a scientific basis, others do not. We need to do better. Innovative strategies need to move into early stage clinical trials as quickly as it is safe, and if successful, these therapies should efficiently obtain regulatory approval and widespread clinical application. In late 2009 and 2010 the Society for Immunotherapy of Cancer (SITC), convened an "Immunotherapy Summit" with representatives from immunotherapy organizations representing Europe, Japan, China and North America to discuss collaborations to improve development and delivery of cancer immunotherapy. One of the concepts raised by SITC and defined as critical by all parties was the need to identify hurdles that impede effective translation of cancer immunotherapy. With consensus on these hurdles, international working groups could be developed to make recommendations vetted by the participating organizations. These recommendations could then be considered by regulatory bodies, governmental and private funding agencies, pharmaceutical companies and academic institutions to facilitate changes necessary to accelerate clinical translation of novel immune-based cancer therapies. The critical hurdles identified by representatives of the collaborating organizations, now organized as the World Immunotherapy Council, are presented and discussed in this report. Some of the identified hurdles impede all investigators, others hinder investigators only in certain regions or institutions or are more relevant to specific types of immunotherapy or first-in-humans studies. Each of these hurdles can significantly delay clinical translation of promising advances in immunotherapy yet be overcome to improve outcomes of patients with cancer