| 1. |
- Hedberg, Ylva, 1975-
(författare)
-
Cell Cycle Regulation in Human Renal Cell Carcinoma
- 2003
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- ABSTRACTCell cycle regulation in human renal cell carcinomaYlva Hedberg, Departments of Medical Biosciences, Pathology, and Surgical andPerioperative Sciences, Urology Andrology, Umeå University, SwedenDeregulated growth control is a hallmark of neoplasia potentially caused by aberrant expression of cell cycle regulatory proteins. The importance of such aberrations in human renal cell carcinoma (RCC) has not been fully clarified. Therefore, the protein expressions of several G1/S regulatory proteins in human RCC were evaluated and their relation to clinico-pathological data was examined.Western blotting and immunohistochemistry were used to detect the proteinexpression of cyclin D1, D3, and E in 80 RCCs. Most tumors expressed higher levels of cyclin D1 (75%) and cyclin E (65%) compared to corresponding normal kidney cortex. In contrast, only 16 % of the tumors had high levels of cyclin D3. In conventional RCCs, low levels of cyclin D1 were associated with large tumor size, aneuploidy and a poor outcome for the patients. High expression of cyclin D3 and Ewere associated with aneuploidy, high proliferation, high TNM-stage, and high nuclear grade. Cyclin E was positively correlated to cyclin D3 but inversely associated with cyclin D1. Cyclin D3 and E were not associated with survival. The majority of RCCs had normal p27 levels, determined by immunohistochemistry, whereas the few tumors with low p27 levels were associated with large tumor size and poor survival.In order to confirm and extend our initial studies, a tissue microarray consisting of 218 RCCs was constructed and cyclin D1, D3, E, p27 were detected by immunohistochemistry. The tissue microarray results were validated by comparing the array data with western analyzes. Due to the large number of tumors analyzed we could evaluate potential differences in expression patterns of cell cycle regulators between conventional, papillary, and chromophobe RCCs. Interestingly, the protein expression differed between RCC types, showing that the conventional tumors generally had high cyclin D1 expression. In contrast, papillary and chromophobe RCCs had high cyclin E expression. Downregulation of p27 was found mostly in chromophobe RCCs. The retinoblastoma protein (pRb) was detected in all RCCs. Phosphorylation of pRb, detected by western blotting or immunohistochemistry and phospho-specific antibodies, was observed in approximately 50% of the tumors. The cdk-inhibitor p16 was not overexpressed suggesting that pRb was functional in the majority of RCCs.In summary, abnormal expression of G1-cyclins and the CDK-inhibitor p27 was common in RCC whereas the main G1/S-substrate, pRb, seemed to be functional. The aberrations further differed between the separate RCC subtypes and were linked to clinical behavior.
|
|
| 2. |
|
|
| 3. |
|
|
| 4. |
|
|
| 5. |
|
|
| 6. |
|
|
| 7. |
|
|
| 8. |
|
|
| 9. |
- Descamps, D, et al.
(författare)
-
Two- and three-photon ionization of rare gases using femtosecond harmonic pulses generated in a gas medium
- 2001
-
Ingår i: Physical Review A (Atomic, Molecular and Optical Physics). - 1050-2947. ; 64:3
-
Tidskriftsartikel (refereegranskat)abstract
- The fifth harmonic of a 60-fs 10-Hz terawatt titanium:sapphire laser generated in Xe gas is used to ionize Xe and Kr atoms by nonresonant two-photon absorption and At atoms through a quasiresonant three-photon process. At relatively low harmonic yields, the variation of the number of Kr and Xe ions with the number of harmonic photons is quadratic. At high harmonic yields, it deviates from a quadratic behavior, which we attribute to the influence of ionization in the harmonic process distorting the harmonic wave front. The two-photon ionization cross sections in Xe and Kr at 160 nm are found to be comparable.
|
|
| 10. |
- Fuxe, J, et al.
(författare)
-
Adenovirus-mediated overexpression of p15INK4B inhibits human glioma cellgrowth, induces replicative senescence, and inhibits telomerase activitysimilarly to p16INK4A
- 2000
-
Ingår i: Cell growth & differentiation. - 1044-9523. ; 11:7, s. 373-384
-
Tidskriftsartikel (refereegranskat)abstract
- The genes encoding the cyclin-dependent kinase inhibitors p16INK4A (CDKN2A) and p15INK4B (CDKN2B) are frequently homozygously deleted in a variety of tumor cell lines and primary tumors, including glioblastomas in which 40-50% of primary tumors display homozygous deletions of these two loci. Although the role of p16 as a tumor suppressor has been well documented, it has remained less well studied whether p15 plays a similar growth-suppressing role. Here, we have used replication-defective recombinant adenoviruses to compare the effects of expressing wild-type p16 and p15 in glioma cell lines. After infection, high levels of p16 and p15 were observed in two human glioma cell lines (U251 MG and U373 MG). Both inhibitors were found in complex with CDK4 and CDK6. Expression of p16 and p15 had indistinguishable effects on U251 MG, which has homozygous deletion of CDKN2A and CDKN2B, but a wild-type retinoblastoma (RB) gene. Cells were growth-arrested, showed no increased apoptosis, and displayed a markedly altered cellular morphology and repression of telomerase activity. Transduced cells became enlarged and flattened and expressed senescence-associated beta-galactosidase, thus fulfilling criteria for replicative senescence. In contrast, the growth and morphology of U373 MG, which expresses p16 and p15 endogenously, but undetectable levels of RB protein, were not affected by exogenous overexpression of either inhibitor. Thus, we conclude that overexpression of p15 has a similar ability to inhibit cell proliferation, to cause replicative senescence, and to inhibit telomerase activity as p16 in glioma cells with an intact RB protein pathway.
|
|
