[Roles of clinical laboratory monitoring in bone marrow and peripheral blood stem cell transplantation]

Hematopoietic stem cell transplantation(HSCT) increase the chances of cure of many hematological malignancy. The clinical laboratory plays a major role in support of HSCT. Both transplantation-specific laboratory test(tissue typing, assessment of graft viability/rejection, evaluation of minimal residual disease, and measurement of immunosuppressive drugs) and routine clinical laboratory tests(biochemical, hematological, serological, urinary, bacteriological, and physiological examinations) are significant. Hematopoietic stem cells(HSC) are usually assessed as CD34+ cells, while immature cells determined by automated hematology analyzers can simply evaluate HCS. These automated immature cell counts are earlier markers of engraftment following transplantation than the traditional indicators(neutrophils and platelets). After transplantation, infections, regimen-related toxicities, graft-versus host disease, veno-occlusive disease, and thrombotic microangiopathy are the serious complications, which are causes of expected mortality and morbidity in HSCT. Clinical laboratory monitoring may contribute early diagnosis and treatment of the complications, resulting in prevention of the adverse events.

Enhanced apoptosis and transforming growth factor-beta1 expression in colorectal adenomas and carcinomas after Sulindac therapy

PURPOSE

We tried to elucidate the effects of sulindac on human colorectal carcinoma.

METHODS

Sulindac (300 mg/day) was administered for two weeks before operation to 33 patients with sporadic colorectal carcinoma (Sulindac Group). Resected specimens were used to detect apoptosis by terminal dUTP nick end labeling and transforming growth factor (TGF)-beta1 expression by immunohistochemistry. The results were compared with those from the historical Control Group. Twenty-nine available preoperative biopsies taken from carcinomas before sulindac prescription and 22 concurrent colorectal adenomas (9 and 13 in Sulindac and Control Groups, respectively) in the resected specimen were also examined regarding TGF-beta1 expression.

RESULTS

In the resected carcinomas and adenomas, more frequent apoptosis and higher TGF-beta1 scores were observed in the Sulindac Group than in the Control Group. Overexpression of TGF-beta1 and apoptosis occurred in the same region in adenomas but not in carcinomas. A positive correlation between TGF-beta1 scores and apoptotic frequency was found in adenomas (P = 0.01, rho = 0.91) but not in carcinomas (P = 0.89, rho = 0.03).

CONCLUSION

We conclude that sulindac induces apoptosis in human colorectal carcinomas as well as in adenomas. Also, one of the antineoplastic effects of sulindac might be mediated by upregulating TGF-beta1 expression, particularly in colorectal adenomas.

Effects of HSP-117, a novel tachykinin NK1-receptor antagonist, on cisplatin-induced pica as a new evaluation of delayed emesis in rats

The effects of a novel tachykinin NK1-receptor antagonist HSP-117 [(2S,3S)-3-[(5-isopropyl-2,3-dihydrobenzofuran-7-yl)methyl]amino-2-phenylpiperidine dihydrochloride] on cisplatin-induced pica, i.e., the eating of nonnutritive substances such as kaolin were examined in rats. HSP-117 inhibited kaolin intake in a dose-dependent manner for 2 days. The 5-HT3-receptor antagonist ondansetron inhibited only on the first day, but not on the second day. These results indicate that the cisplatin-induced kaolin intake on the first day is related to both 5-HT3- and NK1 receptors, while only the NK1 receptor is involved on the second day. Thus, cisplatin-induced continuous pica in rats represents a useful model of not only acute but also delayed emesis.

Extended repair of thoracic aorta through left thoracotomy after aortic root replacement

A patent distal false lumen after repair of type A aortic dissection often poses serious late complications. We present a successful repair of dissecting aortic aneurysm through left thoracotomy, extending from the ascending to descending thoracic aorta after composite graft replacement of the aortic root. Although staged operations, including the elephant trunk procedure, are usually chosen for remaining extensive aortic disease after replacement of the aortic root or the ascending aorta, a single-stage repair from the ascending to the descending thoracic aortas through left thoracotomy can be a favorable option to treat a patient with this type of aortic disease.

Prognostic factors in node-negative squamous cell carcinoma of the thoracic esophagus

BACKGROUND

Among several clinicopathological factors influencing the outcome of patients with esophageal carcinoma, the presence or absence of lymph node metastasis is the most important. Prognostic indicators, however, in patients without lymph node involvement have not been fully understood.

MATERIALS AND METHODS

Out of 247 patients with primary squamous cell carcinoma of the thoracic esophagus between February 1981 and December 1998, 154 patients (62.3%) underwent esophagectomy with curative intent; 78 patients (50.6%) had no lymph node metastasis. Clinicopathological characteristics of those node-negative 78 patients were investigated.

RESULTS

Pathological tumor stages (pT) were pT1 in 44 patients, pT2 in 24 patients, pT3 in 9 patients, and pT4 in one patient. Forty-six patients are alive free of cancer and another one with pT2N0 tumor is alive with recurrence. Four patients died of recurrence; one in pT1 and three in pT3. The remaining 27 patients died of miscellaneous causes other than esophageal cancer. The 1-, 3-, 5-, and 10-year overall survival rates of all 78 patients including in-hospital mortality were 86.3%, 73%, 66.5%, and 34.6%, respectively. The 3- and 5-year survival rates were 75.4% and 67.7% for those with pT1, T2 tumor (n = 68) and 57.1% and 57.1% for those with pT3, T4 tumor (n = 10) (p = 0.0151). The factors influencing overall survival rate were patient age (< 65 vs. > or = 65), depth of invasion (pT1,T2 vs. pT3, T4), time of operation (< or = 420 min vs. > 420 min), and estimated blood loss (< or = 810 ml vs. > 810 ml). More elderly patients died of unrelated causes to esophageal cancer than younger patients. Among those four variables, the patient age (p = 0.0114) and depth of invasion (p = 0.0443) were independent prognosticators for survival determined by multivariate analysis.

CONCLUSION

For follow-up of elderly patients with node-negative esophageal cancer, evaluation of medical problems is more important than detection of recurrence. pT2N0 stage tumors should be considered a group with an excellent prognosis like pT1N0 tumors.

Comparison of mechanical properties of polyvinylidene fluoride and polypropylene monofilament sutures used for flexor tendon repair

We performed an experimental study to evaluate the mechanical properties of polyvinylidene fluoride sutures and to compare their use with that of standard polypropylene sutures for the circumferential, epitendinous suture of a flexor tendon repair. Polyvinylidene fluoride sutures had a smaller suture diameter, a greater knot pull strength and less delayed extension when under creep testing, than polypropylene sutures. Tendons repaired using polyvinylidene fluoride sutures had significantly greater gap and breaking strengths than those repaired using polypropylene sutures.

HTLV-I proviral load correlates with progression of motor disability in HAM/TSP: analysis of 239 HAM/TSP patients including 64 patients followed up for 10 years

To clarify clinical and laboratory findings that may be related to the pathomechanism of HTLV-I-associated myelopathy/tropical spastic paraparesis (HAM/TSP), we analyzed these findings in 239 patients with HAM/TSP, including 64 patients followed up for 10 years after their first examinations, with special interest in the HTLV-I proviral load in peripheral blood mononuclear cells (PBMCs). The proviral load in PBMCs did not differ in terms of modes of HTLV-I transmission. However, the proviral load in patients with age of disease onset greater than 65 years tended to be higher than those with a younger age of onset. In the 64 patients followed up for 10 years, the clinical symptoms deteriorated in 36 patients (56%), unchanged in 26 patients (41%), and improved in 2 patients (3%). HTLV-I proviral load also appeared to be related to the deterioration of motor disability in these patients. To our knowledge, the present study is the first longitudinal study concerning the relationship between the clinical course of HAM/TSP and HTLV-I proviral load. It is suggested that HTLV-I proviral load is related to the progression of motor disability and is an important factor to predict prognosis of patients with HAM/TSP.

Identification of recurrent chromosomal rearrangements and the unique relationship between low-level amplification and translocation in glioblastoma

To elucidate the structural abnormalities and the relationship between chromosome structural disorders and DNA copy number aberrations in tumor cells, we applied the techniques of spectral karyotyping (SKY), comparative genomic hybridization (CGH), and fluorescence in situ hybridization (FISH), using yeast artificial chromosome (YAC) probes for nine human glioblastoma cell lines. One striking finding was that independently derived cell lines had the same recurrent marker chromosomes. Seven recurrent chromosomes were detected by these cytogenetic methods. In particular, cell lines U251, SNB-19, and U373-MG showed very similar karyotypes. It is also interesting that regions of DNA amplification were found translocated and/or inserted at a high rate (91.7%). In all, there were 12 amplified loci in five of the nine cell lines. These amplified chromosomal bands were scattered on the chromosomes, including the normal chromosome, with one exception (7q32-qter in U373-MG). FISH with YAC clones mapping to these chromosomal regions as DNA probes often showed DNA probe signals not only at original chromosomal sites but also in translocated or inserted segments. This form of DNA amplification was characterized by low-level increases (four- to 10-fold) and by translocation or insertion of the relevant chromosomal locus. These studies shed light on typical derivative chromosomes and the relationship between DNA amplification and chromosomal translocation in glioblastoma.

Effect of absorbable polydioxanone flexor tendon repair and restricted active mobilization in a canine model

We performed an experimental study to evaluate the mechanical and histologic healing process of flexor tendon repair using absorbable polydioxanone monofilament followed by active mobilization. Sixty-four canine flexor digitorum profundus tendons were repaired using polydioxanone monofilament or control braided polyester. Animals were evaluated 7, 14, 28, and 42 days after surgery with 12 day 0 control tendons. All repaired tendons healed without rupture or gap formation. Mechanically, all specimens had adequate tensile strength enabling active mobilization. The tendons that were repaired using braided polyester healed without initial tensile depression; however, the ultimate tensile strength values of polydioxanone specimens showed a significant decrease at day 14. Histologically, an inflammatory response was observed around the polydioxanone monofilament; this reaction increased from day 14 to day 42. However, the inflammatory response did not cause large adhesions or large tendon callus formation. This method of using absorbable suture material for tendon repair has the potential for use in the clinical setting.

Budding Yeast GCN1 Binds the GI Domain to Activate the eIF2α Kinase GCN2

When starved for a single amino acid, the budding yeast Saccharomyces cerevisiae activates the eukaryotic initiation factor 2alpha (eIF2alpha) kinase GCN2 in a GCN1-dependent manner. Phosphorylated eIF2alpha inhibits general translation but selectively derepresses the synthesis of the transcription factor GCN4, which leads to coordinated induction of genes involved in biosynthesis of various amino acids, a phenomenon called general control response. We recently demonstrated that this response requires binding of GCN1 to the GI domain occurring at the N terminus of GCN2 (Kubota, H., Sakaki, Y., and Ito, T. (2000) J. Biol. Chem. 275, 20243-20246). Here we provide the first evidence for the involvement of GCN1-GCN2 interaction in activation of GCN2 per se. We identified a C-terminal segment of GCN1 sufficient to bind the GI domain and used a novel dual bait two-hybrid method to identify mutations rendering GCN1 incapable of interacting with GCN2. The yeast bearing such an allele, gcn1-F2291L, fails to display derepression of GCN4 translation and hence general control response, as does a GI domain mutant, gcn2-Y74A, defective in association with GCN1. Furthermore, we demonstrated that phosphorylation of eIF2alpha is impaired in both mutants. Since GCN2 is the sole eIF2alpha kinase in yeast, these findings indicate a critical role of GCN1-GCN2 interaction in activation of the kinase in vivo.

Involvement of calpain for apoptosis in dysfunction of the unaffected testis in rats with experimental testicular torsion

PROBLEM

The dynamics of calpain and involvement of apoptosis in sperm formation disorder of the unaffected testis in rats with experimental testicular torsion were investigated.

METHODS OF STUDY

Using 6-week-old Wistar rats, an experimental unilateral testicular torsion model was prepared. The bilateral testes were excised 1, 3, 5, 7, 14, 35, and 70 days after the left testis was twisted, and the unaffected testes were subjected to immunohistological staining, sodium dodecyl sulfate polyacrilamide gel electrophoresis and Western blotting using anti-calpain antibodies. Apoptosis was detected by the TdT-mediated dUTP biotin nick end-labeling (TUNEL) method.

RESULTS

By immunohistological staining, positive immunostaining by anti-pro mu-calpain antibody was observed in the spermatocyte nucleus, but not with anti-pro m-calpain antibody. The staining was increased until 7 days after testicular torsion, then decreased with progression of sperm formation disorder. By Western blotting, the intensity of staining with anti-pro mu-calpain antibody was increased until 7 days after torsion of the testis. Apoptosis expression in the unaffected testis was significantly inhibited by addition of a calpain inhibitor.

CONCLUSIONS

It was suggested that mu-calpain may be involved in apoptosis expression in sperm formation disorder of the unaffected testis in unilateral testicular torsion.

[Assessment of intra and extrahepatic perfusion during hepatic artery infusion chemotherapy using slow-injected gadolinium-enhanced MR imaging through implanted catheter-port-system]

Twenty-four studies of intra-arterially slow-injected gadolinium-enhanced MR imaging through an implanted catheter-port system (reservoir-MR) were carried out in 15 patients with liver tumor. The flow rate of gadolinium injection was 0.1 ml/sec and a total of 3 mL was injected. Six consecutive phases, each with an acquisition time of 14 seconds, were obtained every 30 seconds. In all studies, the signal intensity of the drug delivery portion became very high. Twenty-three of 24 studies showed intrahepatic perfusion in the first phase. The hepatic vein was enhanced at the first phase in 10 and the second phase in 14. The abdominal aorta was enhanced at the second phase in all 24 studies. The portal vein was enhanced at the first phase in 4, the second phase in 13, and the third phase in 7 studies. Both intra- and extrahepatic perfusion were more clearly demonstrated by reservoir-MRI than by digital subtraction angiography through an implanted catheter-port system (reservoir-DSA); however, morphological changes in the hepatic artery were better demonstrated by reservoir-DSA than by reservoir-MRI.

Perioperative management protocols for children with moyamoya disease

Protocols for prevention of cerebral ischemic attacks caused by hyperventilation resulting from crying, as observed in perioperative pediatric moyamoya patients, were evaluated. The first protocol involved the use of sedation when staff were setting up the intravenous lines, performing neuroimaging studies, and controlling postoperative pain. The second involved the use of wound-handling techniques designed to ease postoperative wound care; these included steristrip closure, use of paraffin gauze and not using adhesive tapes. We compared 14 and 11 surgical cases handled before and after the protocols were introduced, respectively. The number of patients with perioperative cerebral infarction decreased from 2 to 0. Appropriate sedation reduced the incidence of transient ischemic attacks from 28.6% to 3.7%. The average postoperative hospital stay was similarly reduced, from 21.3 days to 16.1 days, as a consequence of the reduced incidence of complications. It is concluded that the perioperative risks can be minimized when invasive procedures are managed according to our protocols.

Prognosis of T4 gastric carcinoma patients: an appraisal of aggressive surgical treatment

BACKGROUND AND OBJECTIVES

Despite precipitous drop in the incidence of gastric carcinoma in Japan, it is still one of the leading causes of death associated with malignant disease. Once the contiguous organs are involved the prognosis becomes dismal. Prognostic factors governing the survival of patients with T4 gastric carcinoma remain unclear.

METHODS

Between 1980 and 1998, 150 patients were treated for T4 gastric carcinoma. Results and prognostic factors were evaluated by univariate and multivariate analyses.

RESULTS

With a 73% resectability, patients with tumor resection had a significantly (P < 0.0001) improved survival rate. Within an acceptable operative mortality (2.6%), apparently curative cases had survival benefit (P < 0.0001) over noncurative cases. In the multivariate analysis, the death risk increased by 2.18 (relative risk) when splenectomy was spared from the operative procedure (P < 0.0071). Presence of esophageal invasion was the other independent prognostic factor in T4 gastric carcinoma patients (relative risk 2.11). Conventional prognostic factors along with the type of organs invaded by the carcinoma had no impact on prognosis.

CONCLUSIONS

Patients with T4 gastric carcinoma might be benefited from aggressive surgery with a curative intent. Whenever possible, splenectomy should be done along with invaded organ resection.

Novel hydroxyphenylurea dual inhibitor against Acyl-CoA

Novel hydroxyphenylurea derivatives were synthesized and their inhibitory potency evaluated against acyl-CoA: cholesterol acyltransferase (ACAT). Quantitative structure activity relationship analysis revealed that their ACAT inhibitory activities were controlled by the hydrophobicity of the whole molecule. the substitution pattern of urea moiety, and the existence of carboxylic acid. The derivatives with strong activities inhibited foam cell formations. Moreover, these compounds showed antioxidative effects against low density lipoprotein (LDL), owing to their characteristic 3-lert-butyl-2-hydroxy-5-methoxyphenyl substructure. Based on the mechanism of atherosclerosis generation, this hydroxyphenylurea-type dual inhibitor against both ACAT and LDL oxidation is expected to be a promising drug for atherosclerosis.

Urinary 8-oxo-7, 8-dihydro-2'-deoxyguanosine and biopyrrins levels among construction workers with asbestos exposure history

It has been suggested that oxidative stress is associated with the cancers caused by asbestos. Since construction workers are sometimes exposed to low levels of asbestos, we investigated whether oxidative stress was elevated in construction workers who had been exposed to low levels of asbestos. The subjects were 48 Japanese construction workers. The defined asbestos-exposed group consisted of subjects who had the history of suspected exposure to asbestos and were diagnosed to have irregular opacities or pleural plaques. We measured the amount of 8-oxo-7, 8-dihydro-2'-deoxyguanosine (8-oxodG) and biopyyrins in the urine of the subjects. The results showed that 8-oxodG and biopyyrins levels in the defined asbestos-exposed group were higher, although they were not statistically significant, than those in the control group. In addition, the urinary 8-oxodG levels tended to correlate positively with the duration of suspected exposure to asbestos. These results suggest that even low-level asbestos exposure may induce oxidative stress and that the resulting's the oxidative stress might be related to lung cancer in construction workers.

Flexor digitorum longus accessorius in the club foot of an infant with Nager syndrome

The case of a male infant is reported who had club foot on the right side and pes adductus on the left side in combination with acrofacial dysostosis; he also demonstrated preaxial anomalies of the upper limbs indicative of Nager syndrome. In addition, an unusual aberrant muscle was discovered during surgical correction of the right club foot.

Significance of clinical risk factors of cystic periventricular leukomalacia in infants with different birthweights

Fifteen appropriate-for-date premature low-birthweight infants with cystic periventricular leukomalacia (PVL) were studied. The infants were stratified into three birthweight groups: less than 1000 g, 1000 g and greater but less than 1500 g, and 1500 g or greater. Reported and new risk factors for PVL were compared with control patients for all patients and each birthweight group. Hypocarbia was significantly related to cystic PVL, especially in infants with birthweight 1000 g or greater (p < 0.03). Sensitivity to hypocarbia might be decreased in infants with birthweight less than 1000 g due to therapy or prematurity. In the group with birthweight less than 1000 g, the proportion of cystic PVL infants on continuous intra-arterial blood-pressure monitoring tended to be lower than the controls, with an almost significant difference (p = 0.05). The duration of tocolysis was significantly longer in the cystic PVL infants than in the controls when the birthweight was greater than 1500 g (p < 0.04). For some risk factors, a significant difference or a tendency of difference was demonstrated only after stratifying the birthweight. For others, the difference became insignificant after stratification. Assessing risk factors after stratifying by birthweight or degree of prematurity is therefore useful.

CONCLUSION

The results suggest that hypocarbia should be avoided to prevent cystic PVL, especially in infants with birthweight of 1000 g or greater, continuous intra-arterial blood-pressure monitoring may be important in infants with birthweight less than 1000 g, and fetal status should be monitored carefully when the duration of tocolysis is prolonged, especially in infants with birthweight of 1500 g or more.

Q fever encephalitis with cytokine profiles in serum and cerebrospinal fluid

A 7-year-old boy with acute encephalitis was proved to have Coxiella burnetii infection. Cerebrospinal fluid but not serum had elevated values of interleukins 1-beta and 6, but not of tumor necrosis factor.

Sulindac inhibits growth of rat colon carcinoma by inducing apoptosis

Sulindac possesses an inhibitory effect on colorectal cancer development. Rat colon cancer cells, ACL-15, inoculated subcutaneously in F344 rats were used. Sulindac was administered at 8 mg/kg twice daily for 7 consecutive days. Sulindac group and control group were compared regarding tumor volume and body weight. At sacrifice, the tumors were collected and examined for tumor-infiltrating lymphocytes, apoptotic index, and microvessel density. The tumor volume in the sulindac group was significantly smaller than that in the control group. Body weight, microvessel density, and tumor-infiltrating lymphocyte score were not significantly different between the two groups. The apoptotic index was significantly higher in the sulindac group than in the control group. Sulindac inhibited tumor growth by inducing apoptosis. These findings may be helpful in designing new treatment strategies in colorectal cancer patients.

Dukes' classification as a useful staging system in resectable squamous cell carcinoma of the esophagus

Dukes' classification for colorectal cancer is simple and has been widely used as a valuable prognostic indicator. It has been used as an assessment of gastric cancer, but it has not been evaluated for esophageal cancer. Of 251 patients with primary squamous cell carcinoma of the thoracic esophagus between February 1981 and April 1999, 155 patients underwent esophagectomy with a curative intent. Clinicopathologic characteristics of those 155 patients were retrospectively investigated according to the Dukes', tumor node metastasis (TNM) and Japanese staging systems. Dukes' classification showed a clear correlation between tumor stage and survival. The 3-year and 5-year survival rates of 64 Dukes' A cases were excellent (97.4% and 93.7%), good for 12 Dukes' B (75% and 75%), and poor for 79 Dukes' C (50.5% and 43.4%), respectively (P < 0.05; Dukes' A vs B, P < 0.0001; Dukes' A vs C, P < 0.10; Dukes' B vs C). TNM stage classification also showed a good correlation between tumor stage and survival, but there were no significant differences between stage 0, I and stage IIA cases (P = 0.2678) and between stage III and stage IV cases (P = 0.8298). In the Japanese staging system, there were no significant differences among stage 0, stage 1, and stage 2 cases (P = 0.4093). Dukes' classification was significantly correlated with tumor size, Borrmann type, histological type, and vessel invasion. Subdivision of Dukes' C according to the number of positive lymph nodes (1-4 vs > or = 5) showed a clearer correlation with survival rather than other subdivisions, such as the metastatic lymph node ratio (< 1.0 vs > 1.0) or the site of lymph node metastasis. Dukes' classification, which incorporates the number of positive lymph nodes, correlates well with tumor progression and provides a simple useful staging system after curative esophagectomy for esophageal cancer. Dukes' A tumor could be proposed as a criterion of early esophageal carcinoma.

Upregulation of HSP47 and collagen type III in the dermal fibrotic disease, keloid

Keloid is a dermal fibrotic disease characterized by excessive accumulation of mainly type I collagen in extracellular matrix of the dermis. We have studied the expression levels of collagen types I and III, and its molecular chaperone HSP47 in keloid lesions and surrounding unaffected skin using Northern and Western blotting and immunohistochemical analyses. Collagen types I and III mRNA levels were found to be upregulated 20-fold in keloid tissues, contradicting previous reports of nearly normal type III collagen levels in this disease. HSP47 expression in keloid lesions was also highly upregulated; eightfold at mRNA level and more than 16-fold at the protein level. Strong upregulation of these three proteins in keloid was confirmed by immunohistochemical staining. These results suggest that accumulation of both type I and type III collagen is important for the development of keloid lesions, and that HSP47 plays a role in the rapid and extensive synthesis of collagen in keloid tissues.

Esophageal resection in elderly esophageal carcinoma patients: improvement in postoperative complications

BACKGROUND

Advanced age is considered to be a relative contraindication for radical esophagectomy with a three-field lymph node dissection.

METHODS

Preoperative risks, postoperative morbidity and mortality, and long-term survival in 55 elderly patients (> or =70 years) who had undergone extensive esophagectomy for esophageal carcinoma were compared with those of 149 younger patients (<70 years).

RESULTS

Elderly patients had worse preoperative cardiopulmonary function and had more frequent postoperative cardiopulmonary complications compared with younger patients (p < 0.05). The postoperative death rate was not statistically different between the elderly (10.9%) and younger groups (5.4%). When the study period was divided into an early and a late phase, the postoperative death rate dropped significantly (p < 0.05) in recent years (1.4%) when compared with the previous era (10.0%). The overall survival rates were not different between elderly and younger patients.

CONCLUSIONS

Preoperative cardiopulmonary risk factors and postoperative complications after esophagectomy were more frequently noticed in elderly patients than in younger patients. A dramatic improvement in postoperative death was noticed in recent years. The long-term survival of elderly patients after extended esophagectomy was almost similar to that in younger patients.

Retinoid X receptor alpha and retinoic acid receptor gamma mediate expression of genes encoding tight-junction proteins and barrier function in F9 cells during visceral endodermal differentiation

Retinoids are critical for differentiation of columnar epithelial cells and for preventing metaplasia of these cells into stratified squamous epithelial cells, in which tight junctions (TJs) are essentially absent. This implies that retinoids might play important roles in regulating the structures and functions of TJs of columnar epithelium. F9 murine embryonal carcinoma cells differentiate into epithelial cells resembling visceral endoderm bearing TJs, when grown in suspension as aggregates in the presence of retinoic acid (RA). We show that RA induces the TJ structure and expression of several TJ-associated molecules, such as ZO-1, occludin, claudin-6, and claudin-7, as well as a barrier function in the genetically engineered cell line F9:rtTA:Cre-ER(T) L32T2, which allows sophisticated genetic manipulations simply by addition of ligands (H. Chiba et al., 2000, Exp. Cell Res. 260, 334-339). Interestingly, our data indicate that a barrier for small substances is generated after that for large ones during de novo formation of TJs. We also compared the RA-induced expression of TJ components and barrier function in RXRalpha(-/-)-RARgamma(-/-) F9 cells with those in wild-type cells and show that the retinoid signals for transduction of these events are mediated by specific RXR-RAR pairs.