Hypoxia inhibits invasion of extravillous trophoblast cells through reduction of matrix metalloproteinase (MMP)-2 activation in the early first trimester of human pregnancy.

During early pregnancy, extravillous trophoblast (EVT) cells are exposed to very low pO(2) values. In this study, we investigated the proteolytic functions and invasiveness of human primary EVT cells under hypoxic conditions to show the early placental pathophysiology. Placental samples (from 5 to 10 weeks gestation) were obtained at termination of pregnancy. Cytotrophoblast cells were separated by Percoll(®) gradient method and cultured on Matrigel(®) to obtain an invasive phenotype (similar to EVT). The invasion capacity (Matrigel-coated invasion assay), migration of the cells (wound healing assay), activity and expression of matrix metalloproteinase (MMP)-2 and tissue inhibitor for MMP (TIMP)-2 (gelatin gel zymography, ELISA, and quantitative RT-PCR), and expression of membrane-type (MT)1-MMP (western blot) were investigated. All cultures (except for quantitative RT-PCR) were performed under 20% oxygen, 5% oxygen, and 5% oxygen with 3 repetitions of 0.1% oxygen hypoxic stimulation for 1 h. Invasion and MMP2 activity of the cells were significantly increased in 20% and decreased in 0.1% oxygen. There was no significant difference in cell migration among the oxygen environments. Concentrations of MMP2 in the supernatant and expression of MT1-MMP were increased in both the 0.1% and 20% oxygen environments. The MMP2 mRNA level was increased after 1-h stimulation with 0.1% oxygen. The TIMP2 concentration was increased only in 20% oxygen, but the mRNA level was decreased in 0.1% oxygen. These results suggested that hypoxia might inhibit the invasive capacity and MMP2 activation of EVT cells in the early first trimester of pregnancy. Decrease in TIMP2 production may reduce the MMP2/TIMP2/MT1-MMP complex and lead to this unique behavior of EVT cells under hypoxic conditions.

A randomized study of screening for ovarian cancer: a multicenter study in Japan.

Ovarian cancer is common in women from developed countries. We designed a prospective randomized controlled trial of ovarian cancer screening to establish an improved strategy for the early detection of cancers. Asymptomatic postmenopausal women were randomly assigned between 1985 and 1999 to either an intervention group (n = 41,688) or a control group (n = 40,799) in a ratio of 1:1, with follow-up of mean 9.2 years, in Shizuoka district, Japan. The original intention was to offer women in the intervention group annual screens by gynecological examination (sequential pelvic ultrasound [US] and serum CA125 test). Women with abnormal US findings and/or raised CA125 values were referred for surgical investigation by a gynecological oncologist. In December 2002, the code was broken and the Shizuoka Cohort Study of Ovarian Cancer Screening and Shizuoka Cancer Registry were searched to determine both malignant and nonmalignant diagnoses. Twenty-seven cancers were detected in the 41,688-screened women. Eight more cancers were diagnosed outside the screening program. Detection rates of ovarian cancer were 0.31 per 1000 at the prevalent screen and 0.38-0.74 per 1000 at subsequent screens; they increased with successive screening rounds. Among the 40,779 control women, 32 women developed ovarian cancer. The proportion of stage I ovarian cancer was higher in the screened group (63%) than in the control group (38%), which did not reach statistical significance (P = 0.2285). This is to our knowledge the first prospective randomized report of the ovarian cancer screening. The rise in the detection of early-stage ovarian cancer in asymptomatic postmenopausal women is not significant, but future decisions on screening policy should be informed by further follow-up from this trial.