Radiosensitivity in breast cancer assessed by the Comet and micronucleus assays.

Spontaneous and radiation-induced genetic instability of peripheral blood mononuclear cells derived from unselected breast cancer (BC) patients (n=50) was examined using the single-cell gel electrophoresis (Comet) assay and a modified G2 micronucleus (MN) test. Cells from apparently healthy donors (n=16) and from cancer patients (n=9) with an adverse early skin reaction to radiotherapy (RT) served as references. Nonirradiated cells from the three tested groups exhibited similar baseline levels of DNA fragmentation assessed by the Comet assay.

Radiation-induced DNA damage and repair in peripheral blood mononuclear cells from Nijmegen breakage syndrome patients and carriers assessed by the Comet assay.

Nijmegen breakage syndrome (NBS) patients and carriers are predisposed to malignancy and are often treated with X-irradiation. In the present study, the single-cell gel electrophoresis (Comet) assay was used to examine radiation-induced DNA damage and repair in peripheral blood mononuclear cells from NBS patients (n=13) and carriers (n=36) of six unrelated families. Cells from apparently healthy donors (n=10) and from breast cancer patients with normal clinical radiosensitivity (n=10) served as controls.

Foldase function of the cathepsin S proregion is strictly based upon its domain structure.

Folding of cathepsin S, like other cathepsin L-like proteases, depends on its proregion. The major part of the proregion forms a small domain distal from the catalytic centre, suggesting function(s) beyond active-site shielding. Using an optimised in vitro trans-refolding assay, we compared reactivation of denatured cathepsin S by the genuine propeptide, wild-type and ten selected mutants.

Folding incompetence of cathepsin L-like cysteine proteases may be compensated by the highly conserved, domain-building N-terminal extension of the proregion.

Folding of cathepsins L and S depend upon their proregion which extends the enzyme part by about 100 amino acids. Only a minority of the prosequence follows the structural template provided by the enzyme part; the majority forms an autonomous minidomain fairly distant from the active site cleft. We suggest that this prodomain may be the structural correlate of a foldase function of the proregion within the cathepsin L-like subfamily of papain-type cysteine proteases and report on a functional approach supporting this hypothesis.