Predictive value of DNA repair gene expression for response to neoadjuvant chemotherapy in breast cancer

Genome-wide analysis using microarrays has revolutionized breast cancer (BC) research. A substantial body of evidence supports the clinical utility of the 21-gene assay (Oncotype DX) and 70-gene assay (MammaPrint) to predict BC recurrence and the magnitude of benefit from chemotherapy. However, there is currently no genetic tool able to predict chemosensitivity and chemoresistance to neoadjuvant chemotherapy (NACT) during BC treatment. In this study, we explored the predictive value of DNA repair gene expression in the neoadjuvant setting. We selected 98 patients with BC treated with NACT. We assessed DNA repair expression in 98 formalin-fixed, paraffin-embedded core biopsy fragments used at diagnosis and in 32 formalin-fixed, paraffin-embedded post-NACT residual tumors using quantitative reverse transcription-polymerase chain reaction. The following genes were selected: BRCA1, PALB2, RAD51C, BRCA2, ATM, FANCA, MSH2, XPA, ERCC1, PARP1, and SNM1. Of 98 patients, 33 (33.7%) achieved pathologic complete response (pCR). The DNA expression of 2 genes assessed in pre-NACT biopsies (PALB2 and ERCC1) was lower in pCR than in non-pCR patients (P=0.005 and P=0.009, respectively). There was no correlation between molecular subtype and expression of DNA repair genes. The genes BRCA2 (P=0.009), ATM (P=0.004), FANCA (P=0.001), and PARP1 (P=0.011) showed a lower expression in post-NACT residual tumor samples (n=32) than in pre-NACT biopsy samples (n=98). The expression of 2 genes (PALB2 and ERCC1) was lower in pCR patients. These alterations in DNA repair could be considered suitable targets for cancer therapy.

Detection of mucopolysaccharidosis type I heterozygotes on the basis of the biochemical properties of plasma alpha-L-iduronidase

BACKGROUND

Mucopolysaccharidosis type I (MPS I) is a disease caused by deficiency of the enzyme alpha-L-iduronidase (IDUA). Since no treatment is currently available for this disorder, the detection of heterozygotes is very important for genetic counseling and prenatal diagnosis. The objective of the present study was to characterize plasma IDUA from MPS I heterozygotes in an attempt to distinguish it from that of normal individuals.

METHODS

We determined the optimum pH, Km, Vmax and Calpha (Vmax/Km) of the reaction and the thermal stability of IDUA at 50 degrees C.

RESULTS

MPS I heterozygotes can be separated from normal individuals on the basis of Km, Calpha and thermal stability of the enzyme.

CONCLUSIONS

Taking into consideration the clinical status of the homozygous offspring, we were able to subdivide the MPS I heterozygotes into various subgroups (Hurler, Scheie or Hurler/Scheie compound), and verified that the Hurler subgroup had a lower optimum pH for IDUA activity than controls and other MPS I subgroups, and that all MPS I subgroups had higher Km and lower Calpha when compared to controls.

Founder BRCA 1 and 2 mutations among a consecutive series of Ashkenazi Jewish ovarian cancer patients

OBJECTIVE

The purpose of this study was to describe the incidence of the three Ashkenazi Jewish founder genetic BRCA 1 and 2 mutations among an unselected, consecutive group of Ashkenazi Jewish ovarian cancer patients.

MATERIALS AND METHODS

From 7/30/96 to 4/12/99, 92 Ashkenazi Jewish patients with histologically confirmed epithelial ovarian cancer had surgery. All of these patients had DNA extracted from 5-microm sections of their paraffin-embedded surgical specimen tissue blocks using the Qiagen QIAamp tissue extraction kit. A multiplex (triplex) polymerase chain reaction was performed to amplify fragments for the 185delAG, 5382insC, and 6174delT mutations. The products were hybridized with normal and mutant probes for each of the three mutations. All clinical data were collected retrospectively and statistical significance was evaluated using the chi(2) test or a two-tailed Fisher's exact test, depending on the sample size.

RESULTS

There were 23 patients positive for one of the three founder BRCA mutations. Fourteen patients were positive for the 185delAG mutation, 2 patients were positive for the 5382insC mutation, and 7 patients were positive for the 6174 delT mutation (61, 9, and 30%, respectively). This represented a 25% incidence (95% CI: 16-34%) of one of the three founder BRCA mutations among our 92 Ashkenazi Jewish ovarian cancer patients. None of the patients was positive for more than one mutation. There was no statistically significant difference in parity, histology, grade, or stage between the BRCA founder mutation positive and negative patients. The difference between the percentage of mutation carriers among patients with one affected first-degree relative (13/22 or 59%) compared to those without at least one affected first-degree relative (10/70 or 14%) was highly significant (P = 0.001).

CONCLUSIONS

Ashkenazi Jewish ovarian cancer patients represent a group with a high likelihood of being carriers of BRCA 1 and 2 genetic mutations, regardless of family history. As a result, all ovarian cancer patients who are of Ashkenazi Jewish descent should be counseled regarding BRCA 1 and 2 genetic screening, as well as the potential implications of these results for the patient as well as her relatives in terms of prognosis, screening, chemoprevention, and consideration of prophylactic surgical procedures.