The levonorgestrel-releasing intrauterine system for endometrial protection during estrogen replacement therapy: a clinical review.

Estrogen replacement therapy (ERT) is a well-established method of managing climacteric symptoms in women approaching the menopause, but it is associated with a significant risk of endometrial hyperplasia if unopposed by concomitant progestogen administration. The levonorgestrel-releasing intrauterine system (LNG-IUS) offers a highly effective method of minimizing this risk and has additional benefits beyond endometrial protection. The LNG-IUS provides excellent contraception, which may still be necessary in perimenopausal women, and is suitable for women with underlying conditions that may preclude their use of estrogen-containing contraceptive methods. It can effectively manage bleeding problems through the transition from perimenopause into menopause, with many women developing amenorrhea. The LNG-IUS is well tolerated with a favorable safety profile, which generally mirrors that of women of reproductive age using it for contraception only. Moreover, the LNG-IUS plus ERT combination does not appear to be associated with clinically relevant effects on plasma lipids or other markers of cardiovascular risk. Women using the LNG-IUS plus ERT also experience improvements in quality of life, and adherence and continuation rates are high. This review will summarize the clinical evidence for the use of the LNG-IUS plus ERT in peri- and postmenopausal women and present the key attributes of this combined therapy.

Bleeding pattern and user satisfaction in second consecutive levonorgestrel-releasing intrauterine system users: results of a prospective 5-year study.

STUDY QUESTION: What is the bleeding pattern during second consecutive levonorgestrel-releasing intrauterine system (LNG-IUS) use? SUMMARY ANSWER: Consecutive use of LNG-IUS is associated with a predictable bleeding pattern, characterized by the absence of the initial period of irregular bleeding seen after interval insertion of an LNG-IUS and a non-bleeding pattern in the vast majority of women. WHAT IS KNOWN ALREADY: With increased popularity of the LNG-IUS for long-term birth control and treatment of heavy menstrual bleeding (HMB), consecutive use of the system is becoming more frequent. One previous study showed 60% amenorrhea rate in consecutive IUS users; however, the sample size was small. STUDY DESIGN, SIZE, DURATION: A prospective multicenter study in four European countries recruited women who wished to continue with LNG-IUS use immediately after the first 5-year period. A total of 204 women were followed up until the end of the first year of the second IUS. Thereafter 170 women continued into the extension phase of the study up to the full 5 years of use of the second IUS and 144 women continued to the end of the study. PARTICIPANTS, SETTING, METHODS: A total of 170 women (mean age 39 years) who had been using their first LNG-IUS for between 4 years 3 months and 4 years 9 months, either for contraception or for treatment of HMB, and who planned to replace the device with a new LNG-IUS, were recruited and followed up to 5 years of the second IUS use. A total of 17 centers in four European countries were involved in the study. Bleeding patterns were analyzed using daily bleeding diaries using 90-day reference periods (RP) for the first year of the second IUS use and for the last RP of each year during Years 2-5 of use. MAIN RESULTS AND THE ROLE OF CHANCE: Approximately 70% of women were free of bleeding during Years 2-5 and up to 49% were amenorrheic. There was a slight increase in the number of bleeding/spotting days of ∼3 days during the first RP immediately after the placement of the second IUS, whereafter the number of bleeding/spotting days returned to the level preceding the second IUS insertion or below that. Absence of bleeding was associated with high overall satisfaction and continuation rates. No serious adverse events assessed as related to the LNG-IUS use occurred during the 5-year period. The cumulative expulsion rate during the 5-year study period was 1.2%. The sample size was large enough to study bleeding patterns, and subjects are likely to represent typical consecutive IUS users, and therefore, the role of chance is small. LIMITATIONS, REASONS FOR CAUTION: The women represent a selected group as they had already successfully used their first IUS for almost 5 years and were willing to continue its use-however, this is currently a common clinical situation. The results may therefore not be extrapolated to first-time users of the LNG-IUS. WIDER IMPLICATIONS OF THE FINDINGS: These data are of importance when counseling women who are making decisions concerning long-term contraception. STUDY FUNDING/COMPETING INTEREST(S): This study was funded by Bayer Pharma AG. P.I. and T.S. are full-time employees of Bayer Pharma AG. O.H. and K. G-D. have received consultancy fees from Bayer Pharma AG. The publication was developed jointly by all authors without third-party involvement and no honoraria were paid for any authors for their contribution to this manuscript. TRIAL REGISTRATION NUMBER: NCT00393198.

Predictors of bleeding and user satisfaction during consecutive use of the levonorgestrel-releasing intrauterine system.

BACKGROUND: Consecutive use of the levonorgestrel-releasing intrauterine system (LNG-IUS) is increasing. However, little is known about factors that predict the bleeding during consecutive use. The objective of this study was to analyse the possible factors which may predict the bleeding pattern during the first year of use of a second LNG-IUS. METHODS: Fertile-aged women (n = 204) who had used their first LNG-IUS for over 4 years and who opted for a second LNG-IUS were recruited. Bleeding data were reported using 90-day reference periods (RPs) starting from the last 90 days of the first LNG-IUS use (baseline), until the end of the first year of the second LNG-IUS (RPs 1-4). RESULTS: Demographic factors such as age, parity, body mass index, indication of LNG-IUS use or smoking could not be identified as predictors for bleeding and spotting (B/S). Mean (+/-SD) number of B/S days was 8.9 (+/-9.1) at baseline. This increased slightly during RP1 and fell to 6.4 (+/-8.1) during RP4. Compared with the mean, women with uterine fibroids or a bleeding pattern of >9 days of spotting or any bleeding at RP1 had more B/S days during RP1-4. Although the number of B/S days decreased progressively from RP1 to RP4 in the group with a bleeding pattern of >9 days of spotting or any bleeding at baseline, such a phenomenon was not observed for women with fibroids. The difference for the change in B/S days between women with and without fibroids was statistically significant at RP3 and RP4. A high degree (91.7%) of satisfaction with the bleeding pattern was observed, with amenorrhoeic women being most satisfied. CONCLUSIONS: Uterine B/S is reduced during consecutive use of the LNG-IUS. Women with uterine fibroids or any bleeding at baseline continued to have more B/S than other women.

Bleeding pattern and safety of consecutive use of the levonorgestrel-releasing intrauterine system (LNG-IUS)--a multicentre prospective study.

BACKGROUND: The LNG-IUS has increasingly been used for contraception, treatment of menorrhagia and endometrial protection during hormone replacement therapy since mid-1990s. Thus, many women use the LNG-IUS consecutively. However, published data on the bleeding pattern regarding consecutive use of the LNG-IUS is scarce. METHODS: We performed a prospective 15-month multicentre study on the bleeding profile, removal and insertion procedures and safety of the second LNG-IUS in fertile-aged women who had used their first LNG-IUS between 4 years 3 months and 4 years 9 months and who opted for the insertion of a second IUS immediately after removal of the first IUS. Bleeding data were reported descriptively starting from the last 90 days of the first IUS use and continuing for up to 1 year. RESULTS: Of the 234 subjects screened, 204 (87%) entered the trial. The median number of bleeding/spotting days during the last 90 days of the first LNG-IUS was 7 (25 and 75% percentiles 0 and 15). Due to bleeding associated with the insertion procedure, this increased to 8 days (4 and 18) during the first 90-day reference period, thereafter decreasing to 4 (0 and 10) days during the second to fourth reference periods. Only one expulsion and no pregnancies, pelvic inflammatory diseases or perforations occurred. A total of 12 subjects (5.9%) prematurely discontinued the study: five due to an adverse event and seven due to other reasons (inclusive of loss to follow-up). CONCLUSIONS: This study confirms the favourable bleeding profile and safety of consecutive use of the LNG-IUS.

Comparison of ovarian cyst formation in women using the levonorgestrel-releasing intrauterine system vs. hysterectomy.

OBJECTIVE: To analyze the effect of the levonorgestrel-releasing intrauterine system (LNG-IUS) on ovarian cyst formation, endometrial thickness and the size of uterus and uterine fibroids by ultrasonography. SUBJECTS AND METHODS: This was a prospective, randomized trial comparing the LNG-IUS and hysterectomy in 236 women (age range 35-49 years) referred for menorrhagia. Transvaginal ultrasound examination was used to study the presence of ovarian cysts, uterine size, endometrial thickness, and the size of the uterus and uterine fibroids during a 12-month follow-up period. RESULTS: At baseline examination, 12 ovarian cysts were detected, eight in the LNG-IUS group and four in the hysterectomy group. During the follow-up period, 14 new cysts had emerged at 6 months and 14 new cysts had emerged at 12 months in the LNG-IUS group, whereas the corresponding figures in the hysterectomy group were three and eight, respectively. All but one of the 14 new cysts (94.1%) detected at 6 months in the LNG-IUS group resolved spontaneously, whereas two out of the eight cysts detected at the baseline examination persisted for 12 months. Three cysts were removed at operation. The relative risk of the occurrence of ovarian cysts was significantly higher in women with LNG-IUS, compared with women who underwent hysterectomy. LNG-IUS did not affect the size of the uterus or uterine fibroids, but it was associated with a decrease in endometrial thickness. The occurrence of cysts did not correlate with age or follicle stimulating hormone levels, but a weak positive correlation between the occurrence of cysts and the presence of irregular bleeding was observed. CONCLUSIONS: LNG-IUS use in the treatment of menorrhagia was associated with the development of ovarian cysts, but these were symptomless and showed a high rate of spontaneous resolution. LNG-IUS did not affect the size of the uterus or the size of uterine fibroids, but decreased the thickness of the endometrium.

Placental expression of syndecan 1 is diminished in preeclampsia.

OBJECTIVE: Syndecan 1 is a cell surface heparan sulfate proteoglycan that binds growth factors and antithrombin III. The objective of this study was to examine whether placental expression of syndecan 1 in preeclampsia differs from that in normal pregnancy and whether gestational age and fetal growth affect syndecan 1 expression. STUDY DESIGN: An immunohistochemical analysis of 30 placentas of women with severe preeclampsia and 15 placentas of women without preeclampsia was performed with the monoclonal anti-syndecan 1 antibody B-B4. RESULTS: In 47% of preeclamptic placentas the immunoreactivity with antibody B-B4 was faint or absent, whereas 93% of the normal placentas exhibited strong immunoreactivity. The reduction in placental expression of syndecan 1 in preeclampsia was not associated with gestational age or impaired fetal growth. CONCLUSION: The expression of syndecan 1 on the chorionic villi is reduced in preeclampsia irrespective of gestational age or fetal growth.

Reduction of syndecan-1 expression is associated with dysplastic oral epithelium.

Syndecans are a family of integral membrane proteoglycans that participate in cell-matrix interactions and growth factor binding. Syndecan-1 expression is induced during keratinocyte differentiation and reduced in squamous cell carcinomas. The purpose of this study was to examine the alteration in syndecan-1 expression in dysplastic oral epithelium. Sixty-six oral biopsy specimens (43 epithelial dysplasias, 3 carcinoma in situ and 20 squamous cell carcinomas) were studied using immunohistochemical methods. The normal epithelium specimens were highly positive for syndecan-1. Fifteen of 46 dysplasias or carcinoma in situ specimens showed negative or weak staining for syndecan-1, two of which were totally negative. Intermediate and strong staining were observed in 17 and 14 dysplasias or carcinoma in situ specimens, respectively. Thirteen (65%) squamous cell carcinomas showed negative or weak staining for syndecan-1, seven of which were totally negative. Only three carcinomas had a strong syndecan-1 expression. Four of the 34 patients with dysplasia who were followed up developed squamous cell carcinoma. All these dysplasias had weak or totally negative syndecan-1 expression. The results suggest that the loss of syndecan-1 is associated with dysplastic changes in oral epithelium.

Association of syndecan-1 with tumor grade and histology in primary invasive cervical carcinoma.

OBJECTIVES: The expression of syndecan-1, a cell surface heparan sulfate proteoglycan, is reduced during malignant transformation of squamous cells. Studies on squamous cell carcinoma of the head and neck have shown that syndecan-1-positive tumors are associated with longer overall and recurrence-free survival. The purpose of this study was to analyze syndecan-1 expression in invasive cervical carcinoma and to examine the association of syndecan-1 expression with prognostic factors and overall survival. METHODS: The study population consisted of 124 patients treated for primary invasive carcinoma of the uterine cervix at the Turku University Central Hospital during the years 1970-1988. The material consisted of 102 (82.3%) squamous cell carcinomas, 16 (12.9%) adenocarcinomas and 1 (0.8%) adenosquamous carcinoma, 1 (0.8%) small cell carcinoma, 1 (0. 8%) adenoid basal carcinoma, 1 (0.8%) carcinosarcoma, and 2 (1.6%) unclassified cervical carcinomas. Syndecan-1 expression was determined on paraffin-embedded tissue blocks using a human syndecan-1-specific monoclonal antibody B-B4 and immunohistochemistry. The expression of syndecan-1 was classified according to staining intensity as well as the percentage of positively stained tumor cells. RESULTS: Staining intensity was strong in 44 (36%) samples, while 24 (19%) specimens remained syndecan-1-negative. In 49 (40%) samples, the percentage of syndecan-1-positive cells was >/=90%. Syndecan-1 expression, as determined by >/=50% positively stained tumor cells, was associated with the grade of differentiation (P = 0.03) and squamous histology (P < 0.001), but was not associated with clinical stage (P = 0.16) or disease-free survival (P = 0.86). Age (P = 0.003) and clinical stage (P < 0.001) were significant prognostic factors, but syndecan-1 expression determined neither by percentage of positively stained tumor cells nor by staining intensity was associated with the outcome. CONCLUSIONS: In cervical carcinoma syndecan-1 is associated with histological differentiation grade and squamous histology, but does not predict clinical outcome.

Immunohistochemical expression of syndecan-1 in human endometrial cancer cells.

There are indications of increased frequency of endometrial cancer, one of the most common malignancies in women. Tissue samples of normal and malignant endometria were obtained post operatively from 30 women. We noted expression of syndecan-1 in 40% of investigated cancers. The most differentiated cancers showed 75% of positively stained specimens, moderately differentiated 40% and poorly differentiated neoplasm did not stain at all. In normal endometrial tissue syndecan-1 expression was regular and distinct in each specimen, but immunoreactivity of the hyperplastic endometrial specimens was absent. The detection of syndecan-1 in endometrial cancer of different clinical and histological stages could be of prognostic value in clinical diagnosis.

Vaginal sonosalpingography in the evaluation of tubal patency.

BACKGROUND: During the past few years, sonosalpingography has been suggested as the first-line method to study tubal patency. This study was launched in order to study the applicability of this method at our institution. METHODS: Thirty-two patients suffering from primary or secondary infertility were evaluated for tubal patency with sonosalpingography using a pediatric Foley urinary catheter and a combination of air and saline solution as a contrast medium. The uterine tubes were evaluated separately and the results were compared to the findings at laparoscopy and chromotubation performed independently. Four patients conceived before their scheduled laparoscopy and were excluded from the study. In addition, the patency of three Fallopian tubes could not be adequately evaluated, leaving altogether 53 uterine tubes that were evaluated by both methods. RESULTS: The findings of both methods agreed in 47 out of 53 tubes (concordance, 88.7%). The sensitivity of sonosalpingography in diagnosing tubal patency was 90.2% and the specificity 83.3%. The positive predictive value for tubal patency by sonosalpingography was 94.9% and the negative predictive value 71.4%. Adverse events of sonosalpingography included moderate to severe abdominal pain in three patients, one vasovagal reaction, and one case of shoulder pain. No infectious complications were recorded. CONCLUSIONS: The results confirm that sonosalpingography utilizing air and saline as a contrast medium is a reliable, simple and well-tolerated method to assess tubal patency in an outpatient setting. In addition, the procedure can be performed without prophylactic antibiotics using a regular pediatric Foley urinary catheter instead of an expensive hysterosalpingography catheter.

Expression of syndecan-1 in human placenta and decidua.

Syndecan-1 is a cell surface heparan sulphate proteoglycan, which binds to the extracellular matrix (ECM), growth factors and antithrombin III. The early expression of syndecan-1 during mouse embryonic development suggests a potential role in the communication between the embryo and the ECM of decidua. Using immunohistochemical methods, the present study showed that the expression of syndecan-1 in the trophoblast cells changes along trophoblast differentiation. The syncytiotrophoblasts in the chorionic villi exhibited an apical expression of syndecan-1. This suggests that the expression is restricted to non-migrating, non-proliferating trophoblasts. The mode of syndecan-1 expression by human placental trophoblasts is independent of gestational age. The expression is not changed in miscarriages. In pre-eclampsia, the staining for syndecan-1 on the villous syncytiotrophoblast is weaker compared to normal pregnancy, but in placental bed the expression is similar. The unique apical localization of syndecan-1 in chorionic villi, not detected in any other tissues, suggests a potential role in fetomaternal communication probably via growth factor binding and in anticoagulation of intervillous circulation.

Expression of syndecan-1 in female reproductive tract tissues and cultured keratinocytes.

The syndecans form a family of cell surface heparan sulphate proteoglycans, which participate in cell-matrix interaction and growth factor binding. The expression of syndecan-1 was studied in tissues of the female reproductive tract with respect to the menstrual cycle, and in cultured vaginal and ectocervical keratinocytes. Immunohistochemical localization of syndecan-1 showed a clear biphasic pattern, with intense staining in the basal cell layer of vaginal and ectocervical epithelium in the proliferative phase, and minimal staining in the secretory phase. Low concentrations of syndecan-1 protein and mRNA were expressed in endometrium throughout the cycle. In cultured keratinocytes isolated from vaginal and ectocervical epithelium, the addition of physiological amounts of 17 beta-oestradiol or progesterone, alone or in combination, failed to produce significant changes in syndecan-1 expression. The cyclic changes of syndecan-1 localization in stratified epithelia of vagina and ectocervix observed in this study may be a result of growth factor action rather than a direct sex steroid regulation.

The role of syndecan-1 in malignancies.

Syndecans form a family of cell surface proteoglycans, which can interact with various effector molecules, such as extracellular matrix (ECM) molecules and growth factors. Syndecan-1 is the most extensively studied member of the syndecan family. It is found mainly in epithelial cells, but its expression is developmentally regulated during embryonic development. It has been shown to mediate cell adhesion to several ECM molecules, and to act as a coreceptor for fibroblast growth factors, potent angiogenic growth factors involved also in differentiation. Syndecan-1 expression is reduced during malignant transformation of various epithelia, and this loss correlates with the histological differentiation grade of squamous cell carcinomas, lacking from poorly differentiated tumours. In squamous cell carcinomas of the head and neck, positive syndecan-1 expression correlates with a more favourable prognosis. Recent experimental studies on the role of syndecan-1 in malignant transformation have shown that syndecan-1 expression is associated with the maintenance of epithelial morphology, anchorage-dependent growth and inhibition of invasiveness in vitro. This review will focus on the biological role of syndecan-1 in normal epithelial differentiation and malignant transformation.

Expression of proteoglycans and hyaluronan during wound healing.

We investigated the expression of proteoglycans (PGs) and hyaluronan (HA) during healing of human mucosal wounds. Biopsy specimens of experimental wounds were taken 1, 3, and 7 days after wounding. Frozen sections were used for immunolocalization of CD44, syndecan-1, basement membrane-associated heparan sulfate proteoglycan (BM-HSPG), decorin, and biglycan. HA was localized in paraffin sections with a specific HA-binding probe. Epithelium showed first signs of migration on Day 1, more progressive migration on Day 3, and epithelial sheets confronted on Day 7. CD44 surrounded migrating keratinocytes at all stages of wound healing. In epithelium, CD44 and HA remarkably localized to the same region. Expression of syndecan-1 was switched from the suprabasal cell layer of unwounded epithelium to the basal cell layer of the migrating wound epithelium. BM-HSPG was absent under migrating keratinocytes. It started to reappear at the basement membrane zone on Day 7. The area under the wound epithelium containing newly synthesized collagen fibers first became positive for decorin on Day 7, whereas staining of biglycan was negative. Granulation tissue was also strongly positive for CD44 and hyaluronan. Our results indicate that migrating keratinocytes express both CD44 and syndecan-1 but not BM-HSPG. During differentiation of keratinocytes, expression of CD44 preceded that of syndecan-1. The results suggest that different HSPGs have multiple functions in keratinocyte migration and differentiation during reepithelialization.

Association between syndecan-1 expression and clinical outcome in squamous cell carcinoma of the head and neck.

Syndecans are a family of cell-surface heparan sulphate proteoglycans which are involved in cell-matrix interactions and growth factor binding. Syndecan-1 binds basic fibroblast growth factor (bFGF) and several components of the extracellular matrix. Syndecan-1 expression is induced during keratinocyte differentiation and reduced during the formation of squamous cell carcinomas (SCCs). The purpose of this study was to examine the association of syndecan-1 expression with prognostic factors and clinical outcome in SCC of the head and neck. Frozen sections of 29 primary SCCs were analysed for syndecan-1 expression using immunohistochemical methods. Intermediate or strong staining for syndecan-1 was associated with a smaller primary tumour size (P = 0.0005) and higher histological grade of differentiation (P = 0.006) than negative or weakly positive staining. In a univariate analysis, syndecan-1-positive tumours were associated with higher overall (P = 0.001) and recurrence-free survival (P = 0.003) than those tumours with no or little syndecan-1 expression. The results suggest that syndecan-1 could be an important prognostic factor of SCC of the head and neck. Further studies on the prognostic significance of syndecan-1 expression in SCCs are warranted.

Immunohistochemical localization of syndecan-1 in normal and pathological human uterine cervix.

Expression of syndecan-1, a cell surface proteoglycan that binds growth factors and extracellular matrix components, was studied in normal and pathological human uterine cervix using immunohistochemical methods. Normal cervical squamous epithelium showed positive staining for syndecan-1 in all cell layers, except the basal cell layer, whereas endocervical columnar epithelium stained weakly. In non-neoplastic reactive lesions, metaplastic squamous cells were positive for syndecan-1, whereas columnar cells showed weak or negative staining. In cervical condylomas, cells showing koilocytotic atypia were positive for syndecan-1. The progression of cervical intraepithelial neoplasia (CIN) grade I to grade III was associated with reduced syndecan-1 expression and localization of syndecan-1 to more superficial cell layers. In squamous cell carcinomas (SCCs), syndecan-1 expression correlated with histological differentiation, being absent from most poorly differentiated tumours. The results suggest that loss of syndecan-1 from atypical cells is an early event during cervical carcinogenesis and show a close association of syndecan-1 expression with preserved epithelial morphology and differentiation.

Expression of syndecan-1 is induced by differentiation and suppressed by malignant transformation of human keratinocytes.

Syndecans comprise a family of integral membrane proteoglycans that presumably participate in cell-matrix interactions and the modulation of growth factor response. Expression of syndecan-1, a cell surface proteoglycan that binds basic fibroblast growth factor (bFGF) and extracellular matrix components, was studied in cultured human keratinocytes from the oral mucosa and in tissue sections derived from various epithelia and carcinomas of the head and neck. For the study, polyclonal antibodies were raised against the core protein of human syndecan-1. The affinity-purified antibody (designated anti-P117) was shown to react specifically with syndecan-1. Abundant expression of syndecan-1 was detected in frozen sections of various stratified epithelia as well as in cultured keratinocytes. Keratinocytes located in the spinous cell layers showed intense immunoreactivity for syndecan-1, while basal cells stained rather weakly, suggesting that the expression of syndecan-1 could be stimulated during the differentiation of keratinocytes. Cultured human keratinocytes were induced to terminally differentiate by increasing the extracellular calcium concentration of the medium. Parallel to the induction of involucrin expression, the mRNA levels of syndecan-1 were found to increase, suggesting that syndecan-1 is indeed induced during keratinocyte differentiation. The molecular mass and glycosaminoglycan composition of syndecan-1 did not change markedly during calcium-induced differentiation. Malignant transformation was associated with marked reduction of syndecan-1 expression, based on the immunoreactivity of anti-P117 in frozen sections from squamous cell carcinomas (SCCs) of the head and neck.(ABSTRACT TRUNCATED AT 250 WORDS)

Expression of syndecan in transformed mouse keratinocytes.

BACKGROUND: Malignant transformation is frequently associated with altered behavior of cells, a phenomenon that also suggests changes in cell-matrix interactions. We have studied expression of syndecan, a cell surface proteoglycan that binds extracellular matrix components and growth factors, in various chemically transformed mouse keratinocyte cell lines that differ in their morphology and tumorigenicity. EXPERIMENTAL DESIGN: A monoclonal antibody, specific for mouse syndecan, and a cDNA clone for mouse syndecan, were used to detect syndecan in seven different keratinocyte cell lines. The glycosaminoglycan composition of syndecan was studied using differential digestions of heparan sulfate and chondroitin sulfate chains. RESULTS: In general, the tumorigenic cells were found to express lower amounts of syndecan, both at protein and mRNA levels, than the nontumorigenic cells. The most tumorigenic cell line CarC revealed barely detectable syndecan expression. Also, molecular polymorphism of syndecan was observed, as three forms of syndecan with different molecular weights appeared on the surfaces of different keratinocytes. The highly tumorigenic cells, that expressed low amounts of syndecan, expressed syndecan with the largest molecular weight. The different molecular weights were shown to reflect an increased amount of both heparan and chondroitin sulfate chains attached to the core protein. An increased shedding of syndecan ectodomain from the membrane-associated domain was observed in cells that express high amounts of mutated Ha-ras p21. CONCLUSIONS: The results suggest, that transformed epithelial cells can modulate the appearance of syndecan on the cell-surface by at least two ways: (a) by altering its glycosylation or (b) by increasing its shedding from the cell surface. These modulations, together with overall suppression of syndecan expression, could be associated with malignant transformation of keratinocytes.

Syndecan in carcinomas produced from transformed epithelial cells in nude mice.

Expression of syndecan, a cell surface proteoglycan, was studied in carcinomas induced by implanting chemically transformed keratinocytes and mammary epithelial cells into nude mice. By immunohistochemistry and in situ hybridization, syndecan was localized in keratinizing cells within moderate- to well-differentiated squamous cell carcinomas in a pattern resembling that of normal epidermis, whereas almost total loss of expression was detected in poorly-differentiated areas within these tumors. In anaplastic spindle cell carcinomas, syndecan expression was barely detectable. In biphasic tumors, induced by mammary epithelial cells, and consisting of cysts overlaying an adenocarcinoma, syndecan was unquely localized to differentiated epithelial structures such as secretory epithelial lining of the cysts as well as aberrant glands and ducts within the carcinoma. Based on the expression pattern of syndecan in the tumors studied, we conclude that the expression of this developmentally regulated molecule is associated with epithelial differentiation also during neoplastic growth.