hMSH2 is the most commonly mutated MMR gene in a cohort of Greek HNPCC patients

Germline mutations in genes encoding proteins involved in DNA mismatch repair are responsible for the autosomal dominantly inherited cancer predisposition syndrome hereditary nonpolyposis colorectal cancer (HNPCC). We describe here analysis of hMLH1 and hMSH2 in nine Greek families referred to our centre for HNPCC. A unique disease-causing mutation has been identified in seven out of nine (78%) families. The types of mutations identified are nonsense (five out of seven) (hMLH1: E557X, R226X; hMSH2: Q158X, R359X and R711X), a 2 bp deletion (hMSH2 1704_1705delAG) and a 2.2 kb Alu-mediated deletion encompassing exon 3 of the hMSH2 gene. The majority of mutations identified in this cohort are found in hMSH2 (77.7%). Furthermore, four of the mutations identified are novel. Finally, a number of novel benign variations were observed in both genes. This is the first report of HNPCC analysis in the Greek population, further underscoring the differences observed in the various geographic populations.

Angiogenesis and p53 expression in the colorectal adenoma-carcinoma sequence

Angiogenesis, the formation of new vessels, is essential for tumor growth and metastasis. Mutations of p53 tumor suppressor gene are frequent and play an important role in colorectal oncogenesis. A role of p53 as an angiogenesis inhibitor has also been proposed. We evaluated angiogenesis and p53 expression in 16 hyperplastic polyps, 35 solitary tubular and tubulovillous adenomas, and 47 cases of sporadic colorectal carcinomas arising on the basis of preexisting adenomas, with standard immunohistochemical techniques. The mean microvessel density (MVD) in carcinomas was significantly higher compared with the respective adenomatous part of the same tumor (27.9 vs. 7; P=0.0001). Linear regression analysis of MVD between cancerous and adenomatous areas showed a significant correlation (P = 0.0001, r = 0.56), raising the possibility that carcinomas arising from better vascularized adenomas might show increased vascularity. The MVD was significantly higher in stage C compared with stage A cases (P=0.04). p53 positivity was detected in 26 of 47 cancerous (55%) and in 14 of 47 adenomatous areas (30%; P = 0.0002). All carcinomas arising from p53-positive adenomas were also p53 positive. p53 positivity associated with a higher MVD in adenomas (P = 0.02), but not in carcinomas (P = 0.78). We conclude that angiogenesis and p53 play a critical role in colorectal neoplasia, and the process of malignant transformation in tumors arising from highly angiogenic adenomas, particularly those carrying p53 mutations, is accelerated with rapid tumor progression from stage to stage, indicating a more aggressive tumor phenotype.

Docetaxel/gemcitabine: salvage chemotherapy in anthracycline-pretreated patients with advanced breast cancer

Docetaxel (Taxotere) and gemcitabine (Gemzar) are active agents against breast cancer. Several phase I studies evaluated different schedules of their combination and clearly demonstrated that docetaxel and gemcitabine can be safely combined in either an every 3-week schedule or in a weekly and biweekly schedule. The toxicity profiles of these combinations were mainly grade 3 and 4 neutropenia and asthenia. Phase I studies also suggested that the docetaxel/gemcitabine combinations are active regimens in pretreated patients with advanced breast cancer. Three phase II studies of patients previously treated with anthracycline-based chemotherapy reported a mean objective response rate of 46% and a mean overall survival of 13.5 months. Two of these trials enrolled patients with anthracycline-resistant or anthracycline-refractory disease; the objective responses using docetaxel/gemcitabine combination were 36% to 55% and 54%, respectively. It is noteworthy that objective responses were also achieved with this regimen in some patients who progressed while receiving taxane-based, front-line chemotherapy. These efficacy results were obtained with a mild toxicity profile. Adverse events were of short duration and easily manageable. Further studies are needed to evaluate this combination as front-line chemotherapy as well as second-line in well-defined subgroups of patients with advanced breast cancer. Furthermore, the combination should be compared with other more standard or investigational regimens.

Indeterminate human immunodeficiency virus type 1 western blot may indicate an abortive infection in some low-risk blood donors

BACKGROUND

The infectious status of persons with an indeterminate human immunodeficiency virus type 1 (HIV-1) Western blot must be established.

STUDY DESIGN AND METHODS

Evaluation of the CD4 and CD8 T-cell subsets and the expression of HIV-1-integrated sequences by Southern blot and polymerase chain reaction were studied in a group of low-risk subjects with an indeterminate Western blot.

RESULTS

From a total of 45,000 blood donors and 50 patients with chronic renal failure on hemodialysis who were tested during the period of 1985 through 1990, 50 sera (0.1%) had an indeterminate Western blot. A low CD4:CD8 ratio (0.7-1.2) was detected in 14 of 24 tested subjects, whereas the unfractionated and adherence-enriched cells of 7 (32%) and 5 (23%) of 22 patients, respectively, could be stained with a p24 monoclonal antibody. A transient positive culture was detected in 3 of 20 subjects, but these viral isolates could not be transmitted to CEM-A310 cells. Ultracentrifuged culture supernatants hybridized under high-stringency conditions with genomic gag-pol (4 cases), env (3 cases), and tat (1 case) cDNA fragments of the HXB2 HIV-1 clone. In one case, DNA obtained from adherent but not unfractionated mononuclear cells contained 3.3- and 3.9-kb env- and gag-pol-related HIV-1 sequences, respectively; these sequences were heavier than expected. Polymerase chain reaction analysis for gag and pol but not env sequences was positive in 1 and 2 of 7 cases, respectively. A female patient with a positive viral culture and who was positive for pol in polymerase chain reaction demonstrated a full seroconversion 19 months later.

CONCLUSION

The results strongly suggest that, rarely, some low-risk subjects with indeterminate Western blot results might be infected with low-level replicative strains or HIV-related viruses; thus, an exhaustive immunologic and virologic workup is needed for the investigation of these subjects.