Dynamic relocalization of NHERF1 mediates chemotactic migration of ovarian cancer cells toward lysophosphatidic acid stimulation

NHERF1/EBP50 (Na⁺/H⁺ exchanger regulating factor 1; Ezrin-binding phosphoprotein of 50 kDa) organizes stable protein complexes beneath the apical membrane of polar epithelial cells. By contrast, in cancer cells without any fixed polarity, NHERF1 often localizes in the cytoplasm. The regulation of cytoplasmic NHERF1 and its role in cancer progression remain unclear. In this study, we found that, upon lysophosphatidic acid (LPA) stimulation, cytoplasmic NHERF1 rapidly translocated to the plasma membrane, and subsequently to cortical protrusion structures, of ovarian cancer cells. This movement depended on direct binding of NHERF1 to C-terminally phosphorylated ERM proteins (cpERMs). Moreover, NHERF1 depletion downregulated cpERMs and further impaired cpERM-dependent remodeling of the cell cortex, suggesting reciprocal regulation between these proteins. The LPA-induced protein complex was highly enriched in migratory pseudopodia, whose formation was impaired by overexpression of NHERF1 truncation mutants. Consistent with this, NHERF1 depletion in various types of cancer cells abolished chemotactic cell migration toward a LPA gradient. Taken together, our findings suggest that the high dynamics of cytosolic NHERF1 provide cancer cells with a means of controlling chemotactic migration. This capacity is likely to be essential for ovarian cancer progression in tumor microenvironments containing LPA.

Differential Skeletal Response to Ovariectomy in Young and Old Rats

OBJECTIVE: The purpose of this study is to evaluate the loss of bone mineral density on ovariectomized (ovx) rat in young and old rats. METHOD: Total 110 Sprague-Dawley female rats which composed of 3 months aged 88 rats and 12 months aged 22 rats were used. They were divided randomly into 5 ovx groups (15 rats for each group) and 5 sham operation group (7 rats for each group). The bone mineral density was measured by Hologic 4,500 Fan Beam bone densitometry at the time of second postoperation week, 4th week, 8th week, and 16th week in young aged group and 4th, 8th week in old aged group. RESULTS: The bone mineral density in young ovx rats was decreased measured at 2 week, 4 week and 8 week, but not 16 week compared with that of sham operation rats (p0.05). CONCLUSION: For the purpose of osteoporosis inducing experiment, young aged rat is more reliable for the detection of bone density change than old aged rat and the bone mineral density change will be continued at least 16 week postovariectomy period.

The Effect of Leg Length Discrepancy on the Strength of Ankle Muscle

OBJECTIVE: This study was designed to evaluate the relation of leg length discrepancy on ankle muscle strength. METHOD: Twenty four adult women were tested (12 leg length equality and 12 leg length discrepancy). Leg length was measured by tape ruler from anterior superior iliac spine to medial malleolus, three times by three different trained examiners. The muscle strength (bilateral ankle dorsiflexors and plantarflexors) was measured by using Cybex 340 dynamometer at 30 degree/sec and 120 degree/sec. RESULTS: The mean value of leg length discrepancy was 0.89+/-0.24 cm. In leg length discrepancy group, the peak torque of ankle plantarflexor were 44.50+/-20.94 Nm in long leg and 51.83+/-12.75 Nm in short leg at 30 degree/sec angular velocity (p<0.05). CONCLUSION: We concluded that there were significant increase in plantar flexor peak torques of short leg than those of long legs at 30 degree/sec (P<0.05). Perhaps the difference of the muscle strength might be due to compensatory mechanism of short leg in propulsion during gait.

Prevalence of Physically Disabled Students in Rural Community

OBJECTIVE: To compare key-person method with census method on the prevalence of physically disabled students and to obtain the prevalence of the physically disabled students in rural community. METHOD: Total 4,890 students of 20 schools in Kyungaido province were surveyed in 1997. Two-thousands and twenty-two students of 8 schools were surveyed by a census method and 2,868 students of 12 schools by a key-person method. RESULTS: The prevalence of the physically disabled students in rural community was 0.53% of the population. The prevalence of the physically disabled students was 0.69% by a census method and 0.42% by a key-person method. This result suggests that there is no significant difference in the prevalence of physically disabled students between the two survey methods (p>0.05). CONCLUSION: A key-person method is as effective as a census method for prevalence survey of physically disabled students in rural communities because of cost effectiveness and less personnel.

The Effect of Growth Hormone on Bone Mineral Density of the Corticosteroid-Induced Osteoporosis in Rat

OBJECTIVE: This study was designed to evaluate the effect of growth hormone on bone mineral density of corticosteoid-induced osteoporosis in male rat. METHOD: Twenty Sprague-Dwaley male rats was studied, divided into four group, each group has 5 rats. The group 1 was treated with saline. The group 2 was treated with corticosteroid (Methylprednisolone 10 mg/kg). The group 3 was treated with corticosteroid and growth hormone (recombinant human growth hormone 0.5 IU/kg). The group 4 was treated with growth hormone after corticosteroid treatment. The treatment duration was 6 weeks for each group. After six weeks of hormone administration, the animals were sacrificed, the bilateral femur were removed and tested for bone mineral density using dual energy X-ray absorptiometry and examined histomorphometrically. RESULTS: Administration of growth hormone after corticosteroid therapy, the growth hormone could reverse the decrease in body weight and bone mineral density induced by corticosteroid therapy (p<0.05). CONCLUSION: When growth hormone is administrated after corticosteroid therapy, the growth hormone can protect the osteoporosis in male rats induced by a high dose of corticosteroid.

The Location of the Center of Pressure in Foot during Stance Phase of Normal Gait by Plantar Pressure Measurement

The purpose of this study was to detect where the center of pressure in foot would be located at the end point of loading response and the terminal stance by the dynamic plantar pressure measurement. Seventeen adults who had the usual feet without a pathologic gait were evaulated simultaneously by the motion analysis using VICON 370, and the plantar pressure measurement using EMED-SF. Two devices were set in the 60 Hz frame. The foot was divided into 3 different zones; hindfoot, midfoot, and forefoot. The end point of loading response was located at the 1.92+/-1.46 frame distal to the hindfoot- midfoot borderline. The end point of terminal response was located at the 2.27+/-1.96 frame distal to the maximal pressure points of metatarsal head. Authors could differentiate each period of stance phase; the initial contact, loading response, mid-stance, terminal stance, and preswing, using the analysis of center of pressure by the dynamic plantar pressure measurement.