Selected features of breast and peritoneal cancers diagnosed in BRCA1 carriers after risk-reducing salpingo-oophorectomy.

BACKGROUND: Since more than two decades Risk-reducing salpingo-oophorectomy (RRSO) is recommended and widely accepted by BRCA1/2 carriers as a method reducing ovarian cancer risk and improving survival rate. After RRSO, there remains a risk of breast cancer and peritoneal cancer. The characteristics of these neoplasms are not well known. In this study, we determined the selected parameters such as age at cancer diagnosis, time from RRSO to the diagnosis of cancer, and significance of BRCA1 mutation type in patients diagnosed with breast or peritoneal cancer during postoperative follow-up. METHODS: The material comprised of 195 BRCA1 carriers who performed RRSO between years 1999-2012. In this period, 16 patients developed cancer (6-primary breast cancer, 3-contralateral breast cancer, 5-relapse of breast cancer, 2-peritoneal cancer). They were subject of the further analysis. RESULTS: During the follow-up period mean age of patients after RRSO at the time of cancer diagnosis was 53.19. The mean age of patients diagnosed with primary breast cancer was 50, contralateral breast cancer - 58.67, recurrence of breast cancer - 51 and peritoneal cancer 60. The mean time periods from RRSO to the diagnosis of primary, contralateral, recurrence breast cancer were 53, 58.67 and 25,4 months respectively and of peritoneal cancer 46 months. BRCA1 c.5266dupC mutation carriers demonstrated significantly shorter time of cancer development compared to patients carrying c.181T > G and c.4035delA mutations. Peritoneal cancer was only observed in two c.181T > G BRCA1 mutation carriers. CONCLUSIONS: The mean age of cancer diagnosis and the mean time periods from RRSO to the diagnosis of cancer are similar to those observed by other researchers. The carriers of c.181T > G and c.5266dupC BRCA1 mutation should be the subject further studies in context of breast and peritoneal cancer risk or time of cancer development after RRSO, respectively.

Thermostability enhancement of an endo-1,4-ß-galactanase from Talaromyces stipitatus by site-directed mutagenesis.

Enzymatic conversion of pectinaceous biomasses such as potato and sugar beet pulp at high temperatures is advantageous as it gives rise to lower substrate viscosity, easier mixing, and increased substrate solubility and lowers the risk of contamination. Such high-temperature processing requires development of thermostable enzymes. Talaromyces stipitatus was found to secrete endo-1,4-ß-galactanase when grown on sugar beet pectin as sole carbon source. The mature protein contained 353 AA and the MW was estimated to 36.5 kDa. It was subjected to codon optimization and produced in Pichia pastoris in 2 l scale yielding 5.3 g. The optimal reaction condition for the endo-1,4-ß-galactanase was determined to be 46 °C at pH 4.5 at which the specific activity was estimated to be 6.93 µmol/min/mg enzyme with half-lives of 13 and 2 min at 55 and 60 °C, respectively. For enhancement of the half-life of TSGAL, nine single amino acid residues were selected for site-directed mutagenesis on the basis of semi-rational design. Of these nine mutants, G305A showed half-lives of 114 min at 55 °C and 15 min at 60 °C, respectively. This is 8.6-fold higher than that of the TSGAL at 55 °C, whereas the other mutants displayed moderate positive to negative changes in their half-lives.

Prophylactic salpingo-oophorectomy in BRCA1 mutation carriers and postoperative incidence of peritoneal and breast cancers.

BACKGROUND: There are no effective methods of diagnosis of early-stage ovarian cancer. Conservative care over patients at high risk of ovarian and breast cancers is ineffective. Prophylactic surgery is considered the best prophylaxis among BRCA1/BRCA2 carriers. METHODS: One hundred ninety-five patients, carriers of one of three most common mutations of the BRCA1 gene (Am J Hum Genet: 66: (6)1963-1968, 2000) in the Polish population (5382insC, 4153delA and C61G), who undergone prophylactic salpingo-oophorectomy. The study group consisted of consecutive mutation carriers living in Poland, in the West Pomeranian province. Histopathological examination of the surgical material failed to reveal presence of malignancy. RESULTS: During follow-up we diagnosed two peritoneal cancers and 14 breast cancers. Diagnosis of breast cancer before prophylactic surgery increased the risk of peritoneal cancer almost three times. Time from diagnosis of breast cancer to prophylactic surgery increased the risk of peritoneal cancer after prophylactic surgery. This was strongly expressed (HR = 5.0; p = 0.030) in cases of over five-year-long delay in prophylactic surgery. Diagnosis of breast cancer before prophylactic surgery correlated with the risk of death (p = 0.00010). Presence of 5382insC mutation decreased and C61G mutation increased the risk of peritoneal cancer (p = 0.049 vs. p = 0.013). CONCLUSIONS: Occurrence of primary peritoneal cancer after prophylactic surgery is similar to that reported in international literature. Primary breast cancer occurred less often than in international literature. We suspect that the risk of development of breast cancer among BRCA1 carriers undergoing prophylactic surgery can differ in a population. The next goal should be to study the molecular basis for the risk of development of malignancies in any population. Carriers of BRCA1 gene diagnosed with breast cancer should undergo prophylactic surgery within five years from the diagnosis of breast cancer.