Multiple mutation in an extended Duchenne muscular dystrophy family.

We have investigated an extended pedigree with three cousins affected by Duchenne muscular dystrophy with apparent transmission through the male line. However, molecular studies have shown that one boy has a de novo duplication, another has a deletion, and the molecular mutation has yet to be defined in the third boy. All three X chromosomes in the affected boys appear to have a different origin. We speculate on the mechanisms by which the Duchenne locus may be particularly prone to mutation in this family and the possible involvement of transposons is discussed. Whatever the mechanism involved, the occurrence of three different mutations in one pedigree is a rare event.     

A phase I pharmacokinetic and pharmacodynamic study of TKI258, an oral, multitargeted receptor tyrosine kinase inhibitor in patients with advanced solid tumors.

PURPOSE: To determine the maximum tolerated dose (MTD) dose-limiting toxicity, and pharmacokinetic and pharmacodynamic profile of TKI258 (formerly CHIR-258). EXPERIMENTAL DESIGN: A phase I dose escalating trial in patients with advanced solid tumors was performed. Treatment was initially as single daily doses on an intermittent 7-day on/7-day off schedule. Following a protocol amendment, a second schedule comprised, during cycle 1, 7-day on/7-day off treatment followed by 14 days of continuous daily dosing; subsequent cycles comprised 28 days of daily dosing. Pharmacokinetics and evaluation of phosphorylated extracellular signal-regulated kinase (ERK) in peripheral blood mononuclear cells were done during the first 28 days of each schedule. RESULTS: Thirty-five patients were treated in four intermittent (25-100 mg/d) and three continuous (100-175 mg/d) dosing cohorts. Observed drug-related toxicities were nausea and vomiting, fatigue, headache, anorexia, and diarrhea. Dose-limiting toxicities were grade 3 hypertension in one patient at 100 mg continuous dosing, grade 3 anorexia in a second patient at 175 mg, and grade 3 alkaline phosphatase elevation in a third patient at 175 mg. One patient had a partial response (melanoma) and two patients had stable disease >6 months. TKI258 pharmacokinetics were linear over the dose range of 25 to 175 mg. Five of 14 evaluable patients had modulation of phosphorylated ERK levels. CONCLUSIONS: The MTD was defined as 125 mg/d. Evidence of antitumor activity in melanoma and gastrointestinal stromal tumors warrants further investigation, and other phase I studies are ongoing. Further pharmacodynamic evaluation is required in these studies to evaluate the biological effects of TKI258.     

Expression of BCL-2 in primary breast cancer and its correlation with tumour phenotype

BACKGROUND:: The role of apoptosis (programmed cell death) in the developmentand progression of breast cancer is unknown. Recently the bcl-2gene has been shown to block apoptosis and thus may promotetumour development. BCL-2 is localised to the luminal cellsof the normal breast, which are considered to be the originof malignant breast disease. PATIENTS AND METHODS:: Immunocytochemistry using anti bcl-2-antibody was performedon 107 breast cancer specimens belonging to node-positive patientsfrom the Ludwig Breast Cancer Studies I-IV and the results werecorrelated with survival, tumour grade, S-phase, oestrogen andprogesterone receptor status and c-erb B-2 expression. Westernand Southern blotting together with immunofluorescence wereperformed on the breast cancer cell lines BT-20, BT-474, MDA-MB-361,T47-D and MCF-7. RESULTS:: In the breast cancer derived cell line MCF-7 BCL-2 is expressedto a level similar to that of the B-lym-phoma cell line Karpas231 with t(14;18)(q32.3; q21.3), but no evidence of a rearrangementor gene amplification was identified. In a study of 107 breastcancers from the International Breast Cancer Study Group TrialsI-IV we have demonstrated a very significant inverse correlationof BCL-2 with c-erbB-2 expression (p = 0.002), and a positivecorrelation with oestrogen receptors (p = 0.001) and progesteronereceptors (p – 0.05). In this study there was no correlationof expression with S-phase fraction in the tumours or with anystage in the cell cycle as assessed in MCF-7 cells. CONCLUSION:: We conclude that BCL-2 might contribute to the malignant phenotypeof breast cancer by modulation of biological behaviour of cancercells. BCL-2, breast cancer, apoptosis     

Deletions and rearrangement of CDKN2 in lymphoid malignancy

Recurrent abnormalities of the short arm of chromosome 9, including translocations and interstitial deletions, have been reported in both leukemia and lymphoma. The pathologic consequences of these abnormalities remain unknown. The cyclin-dependent kinase 4 inhibitor (CDKN2) gene, which maps to 9p21, has been implicated by the finding of a high frequency of biallelic deletions in leukemic cell lines. We have determined the incidence of structural abnormalities affecting CDKN2 by DNA blot in a panel of 231 cases of leukemia and lymphoma and 66 cell lines derived from patients with lymphoid malignancies with defined cytogenetic abnormalities. Structural alterations of CDKN2 were seen in 20 (8.3%) of all fresh cases and 10 (15.1%) of all cell lines. Biallelic CDKN2 deletions were seen in 11 of 53 (21%) cases of B-cell precursor acute lymphoblastic leukemia (BCP-ALL). There was no association with any particular cytogenetic abnormality. Biallelic deletions were also found in high-grade and transformed non-Hodgkin's lymphoma (NHL) of both B- and T-cell lineages. In two cases of transformed NHL, analysis of sequential samples showed loss of CDKN2 with transformation. Neither deletions nor rearrangements of the CDKN2 gene were seen in any of the 119 leukemias of mature B or T cells analyzed. Biallelic deletions of CDKN2 were observed in 6 of 13 NHL cell lines. Three of the 6 cases had undergone transformation from low- to high-grade disease: in 2 of these cases it was possible to show that the CDKN2 deletions were present in fresh material from the patient and were therefore not an artifact of in vitro culture. Rearrangements of CDKN2 were seen in 2 cases (4%) of BCP-ALL, in 1 case of B-NHL, and in 1 Burkitt's lymphoma cell line and suggest the presence of a "hot spot" for recombination in the vicinity of the CDKN2 gene. These data indicate that the loss of CDKN2 expression may be involved in the pathogenesis of a subset of BCP-ALL, some high-grade NHL, and in the transformation of NHL from low- to high-grade disease. CDKN2 deletions and rearrangements occurred in the absence of detectable cytogenetic changes of chromosome 9p in 25 of 30 (83%) cases. Finally, of 10 cases of BCP-ALL that produced overt, transplantable leukemia in mice with severe combined immunodeficiency (SCID), seven showed biallelic CDKN2 deletions. In contrast, none of 11 cases that failed to engraft showed biallelic CDKN2 deletions. BCP-ALL cases that lack CDKN2 expression may have a particular propensity to grow in SCID mice.     

BCL2 translocations in leukemias of mature B cells

Although translocations of the BCL2 gene are frequent in B-cell non- Hodgkin's lymphomas (B-NHL) the incidence, nature, and prognostic significance of similar translocations in the phenotypically related chronic leukemias of mature B cells are unknown. Therefore, we examined 170 cases of B-cell chronic lymphocytic leukemia (B-CLL), 7 cases of B- cell prolymphocytic leukemia (B-PLL), 25 cases of hairy cell leukemia (HCL) and 22 cases of splenic lymphoma with villous lymphocytes (SLVL) with defined cytogenetic abnormalities by DNA blot using both 5' and 3' BCL2 probes to search for rearrangement of the BCL2 locus. Translocation t(14;18) (q32.3;q21.3) was detected cytogenetically in 3 cases of B-CLL. All had breakpoints in the 3' region of BCL2, mapping between the major breakpoint region (MBR) and the minor cluster region (mcr), the breakpoint clusters commonly detected in B-NHL. In 2 of the 3 cases, the breakpoint within BCL2 was mapped to a 1.0-kb EcoRI- HindIII fragment indicating a clustering of breakpoints. Two cases of B- CLL had cytogenetically detectable t(2;18)(p11;q21.3) or t(18;22)(q21.3;q11). Both had rearranged the 5' region of the BCL2 gene to the corresponding lg light-chain gene. Molecular cloning of the t(18;22)(q21.3;q11) showed that the translocation disrupted the BCL2 promoter region and the first untranslated BCL2 exon. Nevertheless, high levels of BCL2 protein were seen in this case. Only 2 other cases in whom cytogenetic analysis was not successful showed rearrangement of the 5' region of BCL2, an overall incidence of 2.3%. No cases of B-PLL, HCL, or SLVL showed either 5' or 3' BCL2 rearrangement. These data confirm the cytogenetic observations that translocations involving the BCL2 locus in all forms of leukemia of mature B cells are rare, and limited to a minor subset of B-CLL. BCL2 translocations in B-CLL involve hot spots of recombination of both the 5' and 3' regions of the BCL2 gene, which are distinct from those commonly seen in B-NHL, suggesting distinct pathogenic mechanisms.