Evaluation of Sleep Parameters and Sleep Staging (Slow Wave Sleep) in Athletes by Fitbit Alta HR, a Consumer Sleep Tracking Device.

Purpose: Sleep is an essential factor for athletes, and it is important to intervene in sleep to manage it. We need a device that can evaluate sleep easily and constantly. Consumer wearable devices can be useful tools for athletes. In order to use consumer wearable devices in clinical research, it is essential to conduct a validation study. Thus, we conducted a validation study to assess the Fitbit Alta HRTM (FBA)- a consumer wearable device with an accelerometer and a heart rate monitor to detect sleep stages and quality against electroencephalographic (EEG) studies in athletes. Patients and Methods: Forty college athletes participated in the study. EEG was applied to participants simultaneously while wearing FBA. Results: Regarding sleep parameters, there was a strong correlation between the total sleep time (TST)-EEG and the TST-Fitbit (r = 0.83; p < 0.001). Regarding the sleep stages, there was a modest correlation between the N3 sleep-EEG and the N3 sleep-Fitbit (r = 0.68; p < 0.001). In addition, there was a strong correlation between the percentage of N3 sleep in between sleep onset and initial rapid eye movement sleep-EEG and those on Fitbit (r = 0.73; p < 0.001). Conclusion: These results demonstrate that FBA facilitates sleep monitoring and exhibits acceptable agreement with EEG. Therefore, FBA is a useful tool in athletes' sleep management.

Alteration of ethanol tolerance caused by the deficiency in the genes associated with histone deacetylase complex in budding yeast.

Upon exposure to 8% ethanol, survival and growth of yeast strains deficient in histone deacetylase complex genes was examined. Of the 18 mutants tested, the Δsir3 and Δsir4 strains showed higher resistance to ethanol, while the Δrco1, Δhos3, Δhda2, and Δhst1 strains were more sensitive than the wild type. Furthermore, these ethanol-resistant patterns varied under aerobic and anaerobic culture conditions.

[A case of laminopathy with the mutation of LMNA gene identified by the exome analysis of disease-related genes].

Laminopathy, caused by mutations in the LMNA gene, include a variety of diseases, such as Emery-Dreifuss muscular dystrophy. A Japanese woman developed progressive muscle weakness, muscle atrophy and joint contractures of upper and lower limbs after the age of two years old. She had restrictive respiratory dysfunction, and developed both supraventricular and ventricular arrhythmias after the fourth decade of life. At 55 years old, she had tracheostomy, required mechanical ventilation and was implanted with the implantable cardioverter defibrillator. The serum level of creatine kinase was within normal range. Electromyography showed polyphasic or large motor unit potentials and reduced interference pattern, while relatively normal recruitment. The exome analysis of disease-related genes revealed a heterozygous pathogenic variant c.1072G>A (p.E358K) in the LMNA gene, which contributed to the diagnosis of laminopathy.

The relationship between body composition and sleep architecture in athletes.

Sleep is essential for athletes to recover physical fitness. It has been suggested that sleep is affected by muscle volume. Compared to female athletes, male athletes with greater muscle volume may have inferior objective sleep quality. This study aimed to assess the relationship between body composition and objective sleep parameters in male and female athletes. The body composition of 17 male and 19 female collegiate athletes were measured, and they underwent overnight home sleep monitoring. Compared with female athletes, male athletes had more muscle mass and less fat mass. Moreover, male athletes had lower sleep efficiency, longer sleep onset latency, higher arousal index, less rapid eye movement (REM) sleep, and lower percentage of slow-wave (N3) sleep in the initial non-REM sleep. Furthermore, the percentage of muscle mass was inversely related, whereas fat mass or percentage of fat mass was directly related to the percentage of N3 sleep in the initial non-REM sleep. Overall, there were no significant association between sex and sleep parameters. However, a significant correlation was found within both subgroups. Objective sleep quality was suggested to be worse in male athletes than in female athletes, implying that sleep architecture may be related to the muscle volume.

Incidence of postmolar gestational trophoblastic disease in androgenetic moles and the morphological features associated with low risk postmolar gestational trophoblastic disease.

In the present study, we evaluated the incidence of postmolar gestational trophoblastic disease (GTD) in molar pregnancy. We also validated the macroscopic diagnosis based on the Japan Society of Obstetrics and Gynecology (JSOG) classification. A total of 297 samples of hydropic villi were classified according to DNA polymorphisms as androgenetic moles, dispermic triploids, or biparental diploids (hydropic abortion), clinically corresponding to complete hydatidiform mole (CHM), partial hydatidiform mole (PHM), and hydropic abortion, respectively. These samples were also classified morphologically based on the JSOG classification. A follow-up study was performed to investigate the incidence of postmolar GTD. A subset of 267 samples eligible for testing were analyzed and diagnosed as androgenetic moles (232 cases), dispermic triploids (20 cases), and biparental diploids (15 cases). Most of the macroscopically diagnosed CHM cases were genetically androgenetic in origin. The PHM cases consisted of 30 androgenetic moles and 12 dispermic triploids. We reviewed the outcomes of 200 patients (178 cases of androgenetic mole, 13 cases of dispermic triploids, and nine cases of biparental diploids). Twenty-eight cases (16%) of androgenetic moles developed postmolar GTD. None of the patients with dispermic triploids developed postmolar GTD. Among the 28 patients who developed postmolar GTD, the shortest diameter of the largest hydropic villi was significantly longer than that of patients not developing postmolar GTD. None of the patients with androgenetic moles who had hydropic villi <2 mm in their shortest diameter developed postmolar GTD. For the patients with dispermic triploids, the risk of postmolar GTD is extremely low. The risk of postmolar GTD is also low in patients with androgenetic moles with small hydropic villi. The JSOG classification based on the morphology of hydropic villi is reliable for the diagnosis of CHM, but inaccurate for the diagnosis of PHM or "microscopic" moles.

[A case of autosomal recessive hypomyelinating leukodystrophy without GJA12 mutation presenting a novel phenotype].

A 50-year-old woman, who had consanguineous parents, developed gait disturbance at age 3, and revealed nystagmus, cerebellar ataxia, peripheral neuropathy, and spastic tetraparesis. She admitted to our hospital at age 14, and the symptoms progressed very slowly. MRI of this case at age 45 showed a remarkable, diffuse hypomyelination of the cerebrum. Her older sister who already deceased at age 16 showed neurological symptoms similar to this case. The patient was found to have no proteolipid protein-1 gene duplications and deletions and base substitution. Her symptoms were considered to be different from those of typical HLD2, 3, 4 and 5. She carried no GJA12 mutations. These facts suggested that this disease is a novel, autosomal recessive hypomyelinating leukodystrophy.

Specific apoptosis induction in human papillomavirus-positive cervical carcinoma cells by photodynamic antisense regulation.

Human papillomavirus type 18 (HPV18) is frequently detected in cervical cancer cells. The viral proteins E6 and E7 are expressed consistently and have oncogenic activities. The E7 protein binds to a tumor suppressor, the retinoblastoma gene product (pRB), however, leading to the stabilization of tumor suppressor, p53 protein. On the other hand, another viral product, E6, forms complexes with p53 and abrogates its function, resulting in tumor progression. These facts imply that the E6 oncogene is one of the ideal targets for directed gene therapy in HPV-positive cervical cancer. In this study, we tried photodynamic antisense regulation of the antiapoptotic E6 expression using a photocross-linking reagent, 4,5',8-trimethylpsoralen, conjugated oligo(nucleoside phosphorothioate) (Ps-S-Oligo). This photodynamic antisense strategy effectively elicited the apoptotic death of HPV18-positive cervical cancer cells through the selective repression of E6 mRNA and consequent stabilization of p53 protein. E7-mediated signals potentially activated the p53 function and mobilized the p53 pathway to deliver pro-apoptotic signals to the cancer cells, leading to the suppression of in vivo tumorigenesis. An extremely low concentration of cisplatin in addition to Ps-S-Oligos further up-regulated p53 activity, provoking massive apoptotic induction. These results suggest that the photodynamic antisense strategy has the great therapeutic potential in HPV-positive cervical cancers.

Activation of STAT3/5 signal pathways in complete mole and repression in choriocarcinoma cell lines.

OBJECTIVE: Because our previous study of microarray suggested that STAT5 and its downstream target, survivin, were up-regulated in complete mole (CM), we clarified the status of STAT-mediated signal transduction in CM and choriocarcinoma (CC). STUDY DESIGN: Proteins from 4 CM and normal villi and from 3 CC cell lines were subjected to Western blot (WB) analysis to evaluate STAT3 and 5 activation. After STAT and MEK inhibitor were added to these cells, the change in survivin expression was analyzed. Immunohistochemical staining was also done on CM and normal villi. RESULTS: WB showed that phosphorylated STAT3 and 5, which are active forms of STAT protein, as well as survivin, were significantly up-regulated in CM. Immunohistochemistry showed positive signals of pSTATs in the cytotrophoblast and syncytiotrophoblast layer in CM but not in normal villi. In contrast, the pSTAT signal was hardly detected by WB in CC cells. However, a high level of survivin expression was maintained in CC by activation of the MEK signal pathway. CONCLUSION: An activated STAT signal may contribute to hyperplastic cell growth of trophoblasts in CM. CC cells might be obtained independently of cytokine signals for tumor cell growth during the carcinogenic process.

K-Ras and H-Ras activation promote distinct consequences on endometrial cell survival.

A considerable amount of evidence indicates that Ras signaling contributes to the development of endometrial cancer. We previously demonstrated that endometrial cancer cells carrying oncogenic [(12)Val]K-ras were susceptible to apoptosis. The present study examined the role of K-and H-Ras in the induction of apoptosis using rat endometrial cells (RENT4 cells). We found that constitutively activated K-Ras promoted apoptotic cell death, whereas the H-Ras mutant rescued rat endometrial cells from apoptosis. Expression of a constitutively active form of Raf-1 (Raf-CAAX) promoted apoptosis, whereas expression of a constitutively active catalytic subunit of phosphoinositide 3-kinase, p110K227E, allowed cells to escape from apoptosis. Moreover, inhibition of the MEK-MAPK pathway by the specific inhibitor, UO126, rescued the cells from apoptosis, whereas the inhibition of phosphoinositide 3-kinase by its specific inhibitor, LY294002, promoted apoptosis in RENT4 cells expressing activated K-Ras. However, both inhibitors promoted apoptosis in RENT4 cells expressing activated H-Ras. This difference in the regulation of apoptosis by the MEK inhibitor between K-Ras- and H-Ras-expressing cells depended on the interaction of effector proteins downstream of each Ras isoform. Finally, to elucidate the role of downstream K-Ras signal pathways, we generated K-Ras effector domain mutants (K12V35S, K12V40C). We examined the incidence of apoptotic cell death induced by the K-Ras effector domain mutants (K12V35S, K12V40C). The relative ratio of phospho-MAPK to phospho-Akt compared with that of mock cells was higher in K12V35S cells than in K12V40C cells. Ectopic expression of K12V35S protein increased the proportion of apoptotic cells, and in turn, the expression of K12V40C protein decreased compared with the expression of K12V protein without the effector domain mutant. These results demonstrate that K- and H-Ras-mediated signaling pathways exert distinct effects on apoptosis and that K-Ras downstream Raf/MEK/MAPK pathway is required for the induction of apoptosis in endometrial cells. Coordination of the two pathways contributes to endometrial cell survival.

Differential diagnosis between complete and partial mole by TSSC3 antibody completely correlates to DNA diagnosis.

Complete hydatidiform moles (CHMs) are a type of androgenetic fertilization without an ovum. Cases of CHM exhibit a generalized swelling of the villi and are known to be highly associated with persistent disease or carcinoma. In contrast, partial hydatidiform moles (PHMs) also show characteristic hydropic changes among the villi, but the incidence of secondary disease is relatively low. Because PHMs are fertilized by one ovum and two sperm and CHMs are fertilized by one or two sperm alone, we considered whether or not maternally imprinted genes might be useful for achieving a differential diagnosis. The validity of the imprinted genes in CHMs was assessed by implementation of a microarray technique. Among the genes examined, TSSC3, SLC22A1L, KCNQ1, and Decorin were shown to be down-regulated, and TSSC3 was the most markedly suppressed of these genes. In this study, 20 cases of CHM, the diagnosis of which was confirmed by DNA polymorphism, were investigated. In all of these cases, the expression of TSSC3 was completely absent, as determined by Western blot analysis. Conversely, 12 cases of PHM, also diagnosed by DNA polymorphism, were examined here; in all of these 12 cases, TSSC3 was found to be expressed normally. Immunohistochemical (IHC) analysis also produced the same results. The complete silencing of TSSC3 in cases of CHM will provide a novel, convenient strategy for the diagnosis of molar lesions in the placenta.

Genetics and molecular markers in gestational trophoblastic disease with special reference to their clinical application.

Gestational trophoblastic disease (GTD) encompasses a diverse group of lesions with specific cytogenetic and molecular pathogenesis. Although cytogenetic studies have been extensively reported, the molecular pathogenesis is poorly understood. We will summarize some of the recent molecular observations and correlate them with the pathology of GTD. Complete mole is androgenetic in origin. Thus, if a monoallelic contribution can be shown in complete mole, this would render the gene susceptible to functional inactivation by 'one-hit' kinetics. Alternatively, uniparental transmission of genes that are subject to parental imprinting in humans would impair their regulation. Loss of NECC1 expression, biallelic deletions at the critical (7p12-7q11.23) region and enhanced H19 expression in choriocarcinoma would reflect the genetic features exhibited by the putative forerunner, complete mole. In addition to the unique genetic features shown in GTD, alterations in gene expression profiles accompanied by malignant conversion of trophoblasts would facilitate the development of choriocarcinogenesis from complete mole. With recent advances in molecular techniques, further work is still necessary to provide a better understanding and useful markers for persistent trophoblastic disease. These may provide useful prognostic indications that may guide the different diagnosis of GTD.

Analysis of a candidate gene associated with growth suppression of choriocarcinoma and differentiation of trophoblasts.

OBJECTIVE: To isolate a choriocarcinoma suppressor gene and analyze its structure and function. STUDY DESIGN: We constructed a polymerase chain reaction-based subtracted fragmentary cDNA library between normal placental villi and choriocarcinoma cell line CC1. A novel homeobox gene, designated NECC1 (not expressed in differ choriocarcinoma clone 1), is included in this library. We analyzed the structure and function of NECC1 with molecular biology. RESULTS: NECC1 comprises an open reading frame of 219 nucleotides encoding 73 amino acids and contains a homeodomain as a consensus motif. NECC1 is located on human chromosome 4q11-q12, and its expression is ubiquitous in the brain, placenta, lung, smooth muscle, uterus, bladder, kidney and spleen. Normal placental villi abundantly expressed NECC1, but all choriocarcinoma cell lines examined and most surgically removed choriocarcinoma tissue samples failed to express it. We transfected this gene into choriocarcinoma cell lines and observed remarkable alterations in cell morphology and suppression of in vivo tumorigenesis. Induction of chorionic somatomammotropin hormone 1 by NECC1 transfection suggested differentiation of choriocarcinoma cells to syncytiotrophoblast-like cells. CONCLUSION: Our results suggest that loss of NECC1 expression is involved in malignant conversion of placental trophoblasts.

Complete hydatidiform mole with coexisting dichorionic diamniotic twins following testicular sperm extraction and intracytoplasmic sperm injection.

We present the first report of complete hydatidiform mole (HM) with coexisting dichorionic diamniotic twins. This pregnancy was achieved after testicular sperm extraction and intracytoplasmic sperm injection (ICSI) for azoospermia in the woman's husband. Standard in vitro fertilization may cause multisperm fertilization and increase triploid partial HM and complete HM, which arise from dispermic fertilization. In contrast, ICSI can avoid multisperm fertilization. In our case, paternal isodisomy in the molar tissue was confirmed by microsatellite analysis suggesting that it resulted from duplication of a haploid paternal genome following monospermic fertilization of an inactivated oocyte or from monospermic fertilization of an inactivated oocyte with a diploid sperm. Although the patient was eager to continue the pregnancy, the size of the HM component increased rapidly and termination of the pregnancy was required for pre-eclampsia-like symptoms at 15 weeks of gestation. After the operation, chemotherapy was initiated for persistent trophoblastic disease.

Induction of human endometrial cancer cell senescence through modulation of HIF-1alpha activity by EGLN1.

Previous observations indicate that transfer of human chromosome (chr.) 1 induces senescence of endometrial cancer cells. To identify the gene(s) responsible for the senescence, we first analyzed the structural integrity of the introduced chr. 1 in immortal revertant from chr.1-transferred HHUA cells. The data demonstrated a correlation between nonrandom deletions within the 1q31-qter region and reversion to immortality. Next, by using a panel of 12 microsatellite markers, we found high frequencies of loss of heterozygosity in the particular 1q region (1q41-42), in surgically removed samples. Then, we screened the genetic mutation of the genes involved in this region, with endometrial cancer panel. Among them, EGLN1, that is a member of prolyl hydroxylase and can facilitate HIF-1 degradation by ubiquitination through the hydroxylation of HIF-1, was mutated at significantly higher frequencies (12/20, 60%). Introduction of wild-type EGLN1 into endometrial cancer cell lines (HHUA, Ishikawa and HWCA), that carry EGLN1 gene mutations induced senescence. This was invoked through the negative regulation of HIF-1 expression. In addition, alternative way of negative regulation of HIF-1 by Factor inhibiting HIF-1(FIH), SiRNA against HIF-1, and HIF-1 inhibitor, YC-1, could also induce senescence. Thus, EGLN1 can be considered as a candidate tumor suppressor on chr. 1q, and our observation could open the new aspect in exploring the machinery of senescence induction associated with HIF-1 signal transduction. These results also suggested the availability of negative regulation of HIF-1 signals for uterine cancer treatment, especially for uterine sarcomas that have worse prognosis and show a high frequency of EGLN1 gene abnormality.

Epigenetic silencing of the imprinted gene ZAC by DNA methylation is an early event in the progression of human ovarian cancer.

ZAC is a paternally expressed, imprinted gene located on chromosome 6q24, within a region known to harbor a tumor suppressor gene for several types of neoplasia, including human ovarian cancer (HOC). We have failed to identify genetic mutations in the ZAC gene in tumor material. Many imprinted genes contain differentially allele-specific-methylated regions (DMR) and harbor promoter activity that is regulated by the DNA methylation. Aberrant DNA methylation is a common feature of neoplasia and changes in DNA methylation at the ZAC locus have been reported in some cases of HOC. We investigated the DNA methylation and ZAC mRNA expression levels in a larger sample of primary HOC material, obtained by laser capture microdissection. ZAC mRNA expression was reduced in the majority of samples and this correlated with hypermethylation of the ZAC-DMR. Treatment of hypermethylated cells lines with a demethylating agent restored ZAC expression. Our studies indicate that transcriptional silencing of ZAC is likely to be caused by DNA methylation in HOC. Forced expression of ZAC resulted in a reduction in proliferation and marked induction of apoptotic cell death. The ZAC-mediated apoptosis signal is p53-independent and eliminated by inhibitors of caspase 3, 8 and 9. Reduced expression of ZAC would therefore favor tumor progression. As there were no significant differences in either DNA methylation or expression of ZAC mRNA between localized and advanced tumors, our data indicates that loss of ZAC is a relatively early event in HOC. (Supplementary material for this article can be found on the International Journal of Cancer website at http://www.interscience.wiley.com/jpages/0020-7136/suppmat/index.html.)

Genome-wide definitive haplotypes determined using a collection of complete hydatidiform moles.

We present genome-wide definitive haplotypes, determined using a collection of 74 Japanese complete hydatidiform moles, each carrying a genome derived from a single sperm. The haplotypes incorporate 281,439 common SNPs, genotyped with a high throughput array-based oligonucleotide hybridization technique. Comparison of haplotypes inferred from pseudoindividuals (constructed from randomized mole pairs) with those of moles showed some switch errors in resolution of phases by the computational inference method. The effects of these errors on local haplotype structure and selection of tag SNPs are discussed. We also show that definitive haplotypes of moles may be useful for elucidation of long-range haplotype structure, and should be more effective for detecting extended haplotype homozygosity indicative of positive selection.

Involvement of IGF2 and H19 imprinting in choriocarcinoma development.

Complete hydatidiform mole is an abnormal pregnancy characterized by grossly swollen villi in the absence of a fetus (Kajii and Ohama 1997, Wake et al., 1978, Jacobs et al., 1980). It is well known that this abnormal pregnancy product is androgenetic in origin. The entire genome of the molar conceptus is paternally derived. The majority of moles result from fertilization of an empty egg by haploid sperm. The paternally derived haploid set then duplicated without cytokinesis and restores diploidy. Invariably, this class of moles has a 46, XX karyotype and is completely homozygous for genetic markers. Fertilization of an empty egg by two sperms is responsible for the remaining case. These moles show a mixture of homozygous and heterozygous patterns of paternally derived genetic markers. Although complete mole is usually a benign process, 10 to 20 percent of cases leads to either invasive mole or choriocarcinoma. This propensity to malignancy has to associate with the genetic features shown in the mole, that imply the formation of homozygosity and the selective inheritance of paternal genome. It has been described in various human malignancies that both genetic features associate with the inactivation of tumor suppressor genes. Homozygosity would lead to the inactivation of tumor suppressor gene in the mole by a signal event occurred on sperm DNAs. In turn, paternal transmission would result in the silencing of particular tumor suppressor genes. Thus, tumor suppressor genes inactivated either by homozygosity formation or by paternal transmission would be involved in the pathogenesis of choriocarcinoma. Both the maternal and paternal genomes are necessary for normal embryonic development in mammals. Parental-origin-specific functional differences between two alleles, known as genomic imprinting, seem to be exploited for a regulatory mechanism crucial for the proper development of both embryonic and extraembryonic tissues. The list of imprinted genes identified is growing rapidly lately in mouse and man (DeChiara TM et al., 1991, Barlow et al., 1991, Bartolomei MS et al., 1991, Leff SE et al., 1992, Hatada I et al., 1993, Giddings SJ et al., 1994, Hayashizaki Y et al., 1994, Villar AJ et al., 1994, Guillemot F et al., 1995). Among these, IGF2 and H19 tightly linked on human chromosome 11 are of special interest because of their reciprocal imprinting and possible association with certain malignancy and congenital abnormalies. The IGF2 gene expressed from the paternally derived allele (Ohlsson et al., 1993, Giannoukalis et al., 1993), whereas the H19 gene is expressed from the maternally derived allele (Rachmilewitz et al., 1992, Zhang et al 1993, Ferguson-Smith et al., 1993).

Transient uterine myometrial contraction associated with moles.

PURPOSE: To examine the incidence of transient distortion of uterine central tissue and myometrial hypointense areas observed on MR images in women with clinically suspicious moles. MATERIALS AND METHODS: The study population consisted of six women aged 15-47 years with clinically suspicious moles (hydatidiform mole in four, invasive mole in one, and microscopic mole in one). The control study population was 105 reproductive-age women (18-52 years) without uterine malignancy, gestational trophoblastic disease, or pregnancy. MR images were analyzed to check for discrepancies of the uterine central tissue configuration. If a discrepancy was observed, the myometrial hypointense area, its diameter, and changes in its shape and location were analyzed. RESULTS: Differences in uterine central tissue configuration and hypointense areas were observed in all six patients. In the control study, only seven cases showed uterine endometrial distortion, and five exhibited hypointense areas. These areas disappeared, changed in shape, or other hypointense areas appeared on subsequent MR images. Significant differences (P < 0.01) in the incidence of uterine central tissue distortion and hypointense areas, and in their maximum diameter between the study and the control groups were observed. CONCLUSION: Uterine myometrial hypointense areas with central tissue distortion, most likely due to transient myometrial contraction, are frequently seen in women with clinically suspicious moles.

Identification of FOXC1 as a TGF-beta1 responsive gene and its involvement in negative regulation of cell growth.

We cloned the forkhead box C1 (FOXC1) gene, a member of the forkhead/winged-helix transcription factor family, as a transforming growth factor-beta1 (TGF-beta1) responsive gene. We showed that TGF-beta1 upregulated transcription of FOXC1 in several human cancer cell lines. Ectopic expression of FOXC1 cDNA in HeLa cells, which lack both copies of the FOXC1 allele, restores the potential of TGF-beta1 to inhibit cell growth by arresting cells in the G0/G1 phase. In addition, screens of primary endometrial and ovarian cancers revealed homozygous deletion of FOXC1 in 6.7% of them, one nonsense and one missense mutation of FOXC1, and transcriptional silencing in 11.7% of primary cancers. Evidence that a significant fraction of primary cancers exhibited somatic mutations suggests that FOXC1 functions as a tumor suppressor through TGF-beta1 mediated signals.

NECC1, a candidate choriocarcinoma suppressor gene that encodes a homeodomain consensus motif.

We isolated a candidate choriocarcinoma suppressor gene from a PCR-based subtracted fragmentary cDNA library between normal placental villi and the choriocarcinoma cell line CC1. This gene comprises an open reading frame of 219 nt encoding 73 amino acids and contains a homeodomain as a consensus motif. This gene, designated NECC1 (not expressed in choriocarcinoma clone 1), is located on human chromosome 4q11-q12. NECC1 expression is ubiquitous in the brain, placenta, lung, smooth muscle, uterus, bladder, kidney, and spleen. Normal placental villi expressed NECC1, but all choriocarcinoma cell lines examined and most of the surgically removed choriocarcinoma tissue samples failed to express it. We transfected this gene into choriocarcinoma cell lines and observed remarkable alterations in cell morphology and suppression of in vivo tumorigenesis. Induction of CSH1 (chorionic somatomammotropin hormone 1) by NECC1 expression suggested differentiation of choriocarcinoma cells to syncytiotrophoblasts. Our results suggest that loss of NECC1 expression is involved in malignant conversion of placental trophoblasts.