Factors regulating SCC antigen expression in squamous cell carcinoma of the uterine cervix

Expression of squamous cell carcinoma (SCC) antigen emerged concurrently with squamous formation of the uterine cervix and increased during the neoplastic transformation of the cervical squamous epithelium. SCC antigen expression differed considerably among the histomorphologic cell types of cervical carcinoma. Large cell nonkeratinizing carcinoma contained high levels of the antigen. In contrast, no appreciable expression of SCC antigen was observed in small cell nonkeratinizing carcinoma. The pattern of SCC antigen expression closely coincided with EGF receptor (EGF-R) expression in cervical squamous neoplasia. This suggests that the expression of SCC and EGF-R in cervical carcinoma is related to the differentiation or dedifferentiation processes of the tumor cells. SCC production by CaSki cervical epidermoid carcinoma cells was stimulated by EGF. It seems likely that an autocrine system, in which EGF serves as the signal, may exist in cervical squamous carcinoma. 17beta-estradiol and L-triiodothyronine were found to upregulate EGF-R expression, proliferative potential and SCC production in the CaSki cervical carcinoma cells.     

Epidermal growth factor receptor expression is associated with rapid tumor cell proliferation in renal cell carcinoma

Epidermal growth factor receptor (EGF-r) expression and tumor cell proliferation rate have been proposed as potential prognostic parameters in renal cell carcinoma (RCC). In this study, immunohistochemical stains using antibodies to EGF-r and the cell proliferation marker Ki-67 (MIB-1) were used to study the relationship between EGF-r expression, tumor cell proliferation, and prognosis in 50 non-papillary RCC extending beyond the renal capsule (pT3). A high Ki-67 labeling index (LI) was associated with poor patient prognosis (P < .05). Thirty-eight cases (76%) expressed strong cell membrane immunoreactivity for EGF-r. There was a tendency toward a shortened survival for EGF-r-positive tumors (P = .08). Tumor growth fraction (Ki-67 LI) was significantly higher in EGF-r-positive tumors than in EGF-r-negative tumors (P < .05), suggesting that rapid tumor proliferation might be responsible for the poor prognosis associated with EGF-r-positive RCC.     

Differential transforming growth factor-beta secretion in adenocarcinoma and squamous cell carcinoma of the uterine cervix

Tumor cells from eight freshly isolated cervical cancers (i.e., four adenocarcinomas and four squamous carcinomas) were analyzed for their production of the immune-inhibitory cytokine transforming growth factor-beta (TGF-beta) in vitro. All fresh adenocarcinomas secreted significant levels of TGF-beta (mean 397, range between 207 and 782 pg/ml/10(5) cells/48 hr). In contrast, no detectable TGF-beta was present in the supernatants from the four fresh squamous carcinoma cultures (P < 0.001). These data suggest that major differences in the secretion of the immunoinhibitory cytokine TGF-beta exist between squamous cell carcinomas and adenocarcinomas of the uterine cervix. Furthermore, these findings suggest that at least some of the differences in the natural biologic behavior, as well as in the response to radiation treatment, between these two histologic types of cervical cancer could be related to differences in secretion of this immune-inhibitory cytokine.     

Angiogenesis in squamous cell carcinoma in situ and microinvasive carcinoma of the uterine cervix

OBJECTIVE: To evaluate angiogenesis in squamous cell carcinoma in situ (CIS) and microinvasive squamous cell carcinoma of the uterine cervix and to investigate the relations among angiogenesis, stromal inflammation, and depth of invasion. METHODS: Three groups of women were studied: 22 controls who had undergone hysterectomy for benign conditions; 18 with squamous cell CIS of the cervix who underwent cone biopsy, hysterectomy, or both; and 14 with microinvasive squamous cell carcinoma who underwent conization of the cervix and subsequent surgical management according to depth of invasion. All specimens were stained immunohistochemically for factor VIII-related antigen. Areas below the basement membrane with the highest angiogenic density were selected. The degree of stromal inflammatory reaction was assessed. Statistical analyses included Kruskal-Wallis, analyses of variance and covariance, Scheffe and Bonferroni-Dunn post hoc procedures, and Pearson correlation analysis. P < .05 was considered statistically significant. RESULTS: Microvessel counts per high-power field (x 400) of microinvasive squamous cell carcinoma of the cervix differed significantly from those of controls and squamous cell CIS (median 34.5 per high-power field, range 9-76 versus median 17, range 7-47, and median 19, range 8-39, respectively; P < .005). Microvessel counts per high-power field in squamous cell CIS did not differ significantly from those of controls (P = .91). Among patients with microinvasive squamous cell carcinoma of the cervix, no significant correlation was found between microvessel counts per high-power field and the depth of invasion (r = 0.19, P = .51). Stromal inflammatory reaction (graded 0-3) differed significantly among controls, squamous cell CIS, and microinvasive carcinoma (mean 0.40, 0.83, and 1.64, respectively; P < .005). CONCLUSIONS: Microinvasive squamous cell carcinoma of the uterine cervix is angiogenic, but depth of invasion is not associated with increased angiogenicity. Squamous cell CIS is not angiogenic.     

Papillary squamous cell carcinoma of the uterine cervix: diagnostic pitfalls

BACKGROUND: In 1989, a Boeing 737-400 aircraft crashed at Kegworth, near Nottingham, England. The survivors suffered a large number of pelvic and lower limb injuries, and approximately one-third of the passengers died. Subsequent research has suggested that the "brace-for-impact" position that passengers are advised to adopt prior to a crash landing might be modified in order to reduce the incidence of such injuries. The aim of this research was to evaluate biomechanically such a modified crash brace position. HYPOTHESIS: A modified brace position would help to prevent injuries to some passengers in the event of an impact aircraft accident. METHODS: Impact testing on forward-facing seats was performed at the Royal Air Force Institute of Aviation Medicine, Farnborough, England. Aircraft seats, mounted on a sled, were propelled down a track to impact at -16 Gx. A test dummy was used as the experimental model. Four dummy positions were investigated: a) upper torso braced forward and lower legs inclined slightly rearward of the vertical; b) upper torso braced forward and lower legs inclined forward; c) upper torso upright and lower legs inclined slightly rearward of the vertical; and d) upper torso upright and lower legs inclined forward. The impact pulses used were based on Federal Aviation Administration guidelines. Transducers located in the head, spine, and lower limbs of the dummy recorded the forces to which each body segment was exposed during the impact. These forces were compared for each brace position. RESULTS: Impact testing revealed that the risk of a head injury as defined by the head injury criterion was greater in the upright position than in the braced forward position. The risk of injury to the lower limbs was dependent in part on the flailing behavior of the limbs. Flailing did not occur when the dummy was placed in a braced, legs-back position. CONCLUSIONS: A modified brace position would involve passengers sitting with the upper torso inclined forward so that the passenger's head rested against the structure in front, if possible. The legs would be positioned with the feet resting on the floor in a position slightly behind the knee. The position differs from those previously recommended in that the feet are positioned behind the knee. This study suggests that such a position would reduce the potential for head and lower limb injury in some passengers, given that only a single seat type and single size of occupant have been evaluated. Standardization to such a position would improve passenger understanding and compliance. Such a recommendation should not obscure the fact that an occupant seated in a forward-facing aircraft seat, restrained only by a lap belt, is exposed to considerable forces during an impact accident. Such forces are capable of producing injuries in the femur, pelvis, and lumbar spine.     

Intestinal adaptation is enhanced by epidermal growth factor independent of increased ileal epidermal growth factor receptor expression

BACKGROUND/PURPOSE: Intestinal adaptation after massive small bowel resection (SBR) is augmented by epidermal growth factor (EGF) via an unknown mechanism. We recently have observed that EGF increases the expression of EGF receptor mRNA and protein content in the remnant ileum after SBR. The purpose of this study was to determine whether the magnitude of EGF-induced receptor expression correlates with intestinal adaptation. METHODS: A 50% proximal SBR or sham operation (bowel transection with reanastomosis) was performed on male ICR mice. Animals from each group were then selected randomly to receive either human recombinant EGF (150 microg/kg/d) or saline by twice daily intraperitoneal injections. The remnant ileum was harvested at 1 week, and parameters of adaptation measured as changes in protein content. Ileal EGF receptor mRNA was quantitated using a ribonuclease protection assay. Changes in the expression ileal EGF receptor protein were determined by Western blot after immunoprecipitation. Comparisons of mean values between groups was performed using analysis of variance (ANOVA) and a P value of less than .05 was considered significant. Values are presented as mean +/- SEM. RESULTS: EGF was mitogenic to the ileum after sham operation as monitored by increases in ileal protein content (2.21 +/- 0.002 mg/cm Sham v 2.97 +/- 0.25 mg/cm Sham +/- EGF; P < .05). After SBR, adaptation resulted in increased ileal protein content (4.45 +/- 0.27 mg/cm), which was substantially boosted by EGF (5.98 +/- 0.39 mg/cm; P < .05). No differences were detected in ileal EGF receptor mRNA or protein expression between Sham or SBR groups that did not receive EGF. However, EGF significantly enhanced the expression of ileal EGF receptor mRNA to an equal extent after both sham and SBR (approximately threefold). The magnitude of this increase in EGF receptor protein (four- to sixfold) was similar in both EGF groups as shown by Western blotting. CONCLUSIONS: Changes in ileal EGF receptor expression are not mandatory for adaptation to occur. EGF upregulates the expression of mRNA and protein for its own intestinal receptor in vivo. Because EGF-induced receptor expression was comparable after both SBR and Sham operation, the beneficial effect of EGF during adaptation is likely caused by other factors in addition to increased receptor expression.     

Fibroblast growth factor receptor expression reflects cellular differentiation in human oral squamous carcinoma cell lines

This study examined the expression of fibroblast growth factor receptor 2 (FGFR 2) splice variants, IIIb and IIIc, in normal and malignant human oral keratinocytes and in normal oral fibroblasts by RT-PCR using both exon-specific primers and primers common to both FGFR 2 isoforms. Fibroblasts expressed exclusively FGFR 2/IIIc whilst the normal and malignant keratinocytes co-expressed FGFR 2/IIIb and FGFR 2/IIIc. Well-differentiated keratinocytes expressed proportionally more FGFR 2/IIIb than IIIc whereas the poorly-differentiated cells expressed more FGFR 2/IIIc than IIIb. The normal and malignant keratinocytes, but not fibroblasts, expressed an additional amplification product, which consisted of both IIIb and IIIc of FGFR 2 joined by an extra base pair and with the intronic sequence removed. The results indicate that the expression of FGFR 2 isoforms reflects the degree of cellular differentiation in normal and malignant human oral keratinocytes and that receptor complexes of FGFR 2/IIIb and IIIc may regulate ligand-receptor interactions.     

Prognostic value of epidermal growth factor receptor expression in endometrioid endometrial carcinoma

We report here a retrospective study of epidermal growth factor receptor (EGFR) expression in 140 patients with human endometrioid endometrial carcinoma (median period of follow-up, 43.8 months; ranging from 1 to 155 months). Tumor specimens were immunohistochemically examined for the overexpression of EGFR, and the correlation among EGFR status, various clinicopathologic parameters, and prognosis was statistically evaluated. Monoclonal antibody (clone 31 G 7), which recognizes the extracellular domain of the EGFR molecule, was used for immunostaining. Ninety-four of 140 cases were immunohistochemically positive for EGFR (67.1%). The presence or absence of EGFR did not correlate with surgical stage, depth of myometrial invasion (DI), or lymph node involvement, but did correlate with histological grade and patient's age. Furthermore, patients with EGFR-positive endometrial carcinoma had a statistically significant shorter length of survival than those with EGFR-negative tumors (P = .018). This trend is more apparent among the patients more than 50 years old (P = .003). When adjusted for surgical stage, DI, and patient age, EGFR status retained prognostic value by multivariate analysis. However, when adjusted for surgical stage, histological grade, DI, and patient age, EGFR status failed to retain prognostic value by multivariate analysis. The results of this study suggest that EGFR expression is correlated with histological grade and greater invasiveness of human endometrioid endometrial carcinoma.     

Inhibition of human squamous cell carcinoma growth in vivo by epidermal growth factor receptor antisense RNA transcribed from the U6 promoter

BACKGROUND: Squamous cell carcinomas of the head and neck (SCCHN), unlike normal mucosal squamous epithelial cells, overexpress epidermal growth factor receptor (EGFR) messenger RNA and protein. EGFR protein is required to sustain the proliferation of SCCHN cells in vitro. To determine whether EGFR expression contributes to tumor growth, we investigated the effect of suppressing EGFR expression in tumor xenografts through in situ expression of antisense oligonucleotides. METHODS: Intratumoral cationic liposome-mediated gene transfer was used to deliver plasmids capable of expressing sense or antisense EGFR sequences into human head and neck tumors, which were grown as subcutaneous xenografts in nude mice. The oligonucleotides were expressed under the control of the U6 RNA promoter. RESULTS: Direct inoculation of the EGFR antisense (but not the corresponding sense) plasmid construct into established SCCHN xenografts resulted in inhibition of tumor growth, suppression of EGFR protein expression, and an increased rate of apoptosis (programmed cell death). Sustained antitumor effects were observed for up to 2 weeks after the treatments were discontinued. CONCLUSION: These results suggest that interference with EGFR expression, using an antisense-based gene therapy approach, may be an effective means of treating EGFR-overexpressing tumors, including SCCHN.     

Coexpression of cholesterol sulfate and cytokeratin as tumor markers in well-differentiated squamous cell carcinoma of the human uterine cervix

The expression of cholesterol sulfate (CS) is known to increase during squamous differentiation of keratinocytes and to activate the epsilon, eta, and zeta forms of protein kinase C as a signal transduction molecule for the subsequent expression of transglutaminase-1 (TG-1) and cytokeratins. To gain further insight into the regulation of cellular differentiation and tumorigenesis by CS, we examined the concentration and the potential for synthesis of CS in seven and four surgical specimens from human ovarian and uterine cervical cancer patients, respectively, and eight cell lines established from human uterine cervical cancer patients and compared them for the rate of expression of cytokeratin. CS was present in all of the uterine cervical cancer tissue specimens but only in the mucinous type of cystadenocarcinoma among ovarian cancer tissue specimens, and cytokeratin was highly expressed in the tissues with a high concentration of CS, which were classified as well-differentiated on the basis of morphological examination. Similarly, cells derived from a keratinizing type of well-differentiated cervical carcinoma demonstrated strong potential for synthesis of CS, stained positive with anti-cytokeratin antibody, and exhibited a higher specific activity of TG-1, whereas the cells without CS did not stain positive with anti-cytokeratin antibody and exhibited a lower specific activity of TG-1. These findings indicate that CS is coexpressed with TG-1 and cytokeratin in the well-differentiated types of squamous cell cancers as a tumor marker.     

Epidermal growth factor receptor ectodomain in the urine of patients with squamous cell carcinoma

Female Sprague-Dawley rats were ovariectomized (OVX) or sham-operated at 3 months of age and maintained untreated for 1 year after surgery. Baseline control and OVX rats were killed at the beginning of treatment when the rats were 15 months of age and 1 year postovariectomy. The remaining rats were treated with hPTH 1-34 (80 micrograms/kg BW, 5 days/week) or vehicle for 10 weeks. Quantitative bone histomorphometry was performed on undecalcified longitudinal sections of the proximal femur from each rat. Baseline OVX rats exhibited cancellous and cortical osteopenia at the femoral neck as their mean cancellous bone volume and cortical width were significantly decreased compared to the means for baseline control rats. In addition, baseline OVX rats had increased osteoblast and osteoclast surfaces and a greater cancellous bone formation rate than baseline control rats. OVX rats remained osteopenic with no further bone loss from the femoral neck after 10 weeks of vehicle treatment. In contrast, cancellous bone volume and cortical width in OVX rats treated with PTH were increased to the level of vehicle-treated control rats. The hormone restored lost bone in the femoral neck of OVX rats by markedly stimulating both cancellous and cortical bone formation. These histomorphometric findings in concert with recent biomechanical studies of bone strength indicate that the femoral neck of aged OVX rats is a promising sample site for studies of the prevention and treatment of bone loss induced by estrogen depletion.     

Vascular endothelial growth factor expression in head and neck squamous cell carcinoma

BACKGROUND: Angiogenesis is an essential process required for growth and metastasis in cancer. In breast, gastric, and prostate cancer, vascular endothelial growth factor (VEGF) has been implicated in angiogenesis; however, little is known about VEGF in HNSCC. In this study, we hypothesize that VEGF is present in elevated levels in HNSCC and may therefore play a role in promoting angiogenesis. METHODS: We obtained tumor tissue from 63 HNSCC patients undergoing primary resection. All tissue samples were analyzed by immunohistochemistry (IHC) techniques for the presence and localization of VEGF; however, only 36 had sufficient amounts of tissue for quantitative analysis of VEGF by ELISA. Nine control specimens taken from patients undergoing uvulopalatopharyngoplasty were also analyzed. RESULTS: In all 63 of our patient samples we found VEGF to be present and localized to the cancer cells and endothelial cells. The poorly differentiated cancer cells stained more intensely in comparison with the well-differentiated ones. There was a 20-fold increase in the patient levels when compared with controls levels (P > or =0.05). Analysis by enzyme-linked immunosorbent assay revealed elevated mean levels of VEGF (241 +/- 326 pg/mg total protein [TP]) with a range of 2 to 1484 pg/mg TP. The control specimens had mean levels of 13 +/- 11 pg/mg TP and a range of 1 to 78 pg/mg TP. Patients who exhibited higher levels of VEGF tended to have a higher rate of disease recurrence (P < or =0.048) and shorter disease-free interval (P < or =0.05). CONCLUSIONS: The expression of VEGF in elevated levels in the HNSCC tumor microenvironment appears to be associated with more aggressive disease. Based on our results, VEGF may be an important angiogenic factor associated with cancer cells and endothelial cells in HNSCC. Further studies are needed to better define the role of VEGF in HNSCC and its role as a potential target for therapeutic intervention.     

Coexistence of endometrioid ovarian tumor and squamous cell carcinoma of the cervix

A case of the coexistence of the endometrioid ovary carcinoma and frank cervical carcinoma was shown. The diagnostic procedure, surgery and complementary therapy were described. On the basis of the follow-up of the patient it seams that the coexistence of these carcinomas neither accelerate the development of disease nor make worse the prognosis.     

Small-cell neuroendocrine carcinoma of the uterine cervix associated with micro-invasive squamous cell carcinoma and adenocarcinoma in situ

A case of small-cell neuroendocrine carcinoma of the uterine cervix associated with squamous cell carcinoma and adenocarcinoma in situ is reported. The tumor consisted mainly of uniform small cells with a population of intermediate cells that resembled carcinoid tumor cells. Foci of micro-invasive squamous cell carcinoma and adenocarcinoma in situ were recognized separately, adjacent to the main tumor. Both Grimelius stain and immunostaining of serotonin were positive for small-cell and intermediate-cell carcinoma. Neurosecretory granules were demonstrated by electron microscopy. Microacini with positive mucin staining and microvilli-like structures suggested glandular or exocrine differentiation of the tumor. Three distinctive types of differentiation, neuroendocrine, exocrine and squamous characteristics, were expressed in the tumor.     

Invasive squamous cell carcinoma of the cervix: is HLA-DQ a disease marker in Jewish patients?

HLA class I and class II were investigated in 30 Israeli patients with invasive squamous cell carcinoma of the cervix and compared to healthy controls. None of the studied serological specificities were found to be associated with the disease. Genomic DNA from the patients was amplified by PCR, dot-blotted and hybridized with sequence specific oligonucleotide probes defining the known DQA1 and DQB1 allelic variants. Fifteen out of the 30 patients tested (50%) were found to carry the DQA1*0501 allelic variant, which is common in the local healthy population (67%). DQB1*0302 was found in eight out of 30 patients (27%) while this allele was present in 17% of the healthy population, a difference which is not statistically significant. Our data indicate that there is no apparent association between invasive squamous cell carcinoma of the cervix and the HLA antigens and alleles studied including the alleles of the DQA and DQB loci in the Israeli population. Our findings indicate that MHC genes could not be useful in the diagnosis of squamous cell carcinoma of the cervix.     

Sialidase gene transfection enhances epidermal growth factor receptor activity in an epidermoid carcinoma cell line, A431

Glycosphingolipids expressed in cancer cells have been implicated in the modulation of tumor cell growth through their interaction with transmembrane signaling molecules such as growth factor receptors. For glycosphingolipids to interact with growth factor receptors, the presence of sialic acid seems to be essential. Stable transfection of a gene encoding a soluble Mr 42,000 sialidase into a human epidermoid carcinoma cell line (A431) provided an approach by which the level of terminal lipid-bound sialic acid on the cell surface could be altered. In the sialidase-positive clones, the level of ganglioside GM3 was diminished, and little change was observed in protein sialylation. Sialidase-transfected cells grew faster than control cells. Sialidase expression did not modify the binding of epidermal growth factor (EGF) to its receptor but enhanced EGF receptor (EGFR) tyrosine autophosphorylation as compared to that of parental cells or cells transfected with the vector (pcDNA3) alone. Moreover, the phosphorylation of the EGFR, as well as other protein substrates, was observed at low EGF concentrations, suggesting an increase in the receptor kinase sensitivity. These data provided evidence that changes in ganglioside expression in cancer cells by appropriate gene transfection can dramatically affect EGFR kinase activity. Hence, the modulation of ganglioside expression may represent an approach to alter tumor cell growth.     

Vascular endothelial growth factor expression is increased in renal cell carcinoma

PURPOSE: To compare the expression of VEGF in renal cell carcinoma (RCC) and normal kidney. MATERIALS AND METHODS: RT-PCR and Western blot analysis were performed on tumour and normal adjacent kidney collected from 31 patients (29 RCC and 2 oncocytomas) as well as proliferating vascular endothelial cells (VEC) in culture. RESULTS: Expression of 3 VEGF isoforms was detected in normal renal parenchyma and all ROC by RT-PCR, but was not apparent in proliferating VEC. In 27 RCC, Western blot analysis demonstrated 3-37 fold increases in VEGF expression when compared to normal parenchyma. Immunohistochemistry demonstrated VEGF staining of both tumour cells and adjacent vascular endothelium. Normal kidney showed no staining for VEGF. In the 2 remaining RCC and both oncocytomas VEGF was not increased. CONCLUSIONS: VEGF expression is increased in RCC and may have a paracrine effect in these tumours in stimulating angiogenesis.     

Increased epidermal growth factor receptor expression in metaplastic bronchial epithelium

Epidermal growth factor receptor (EGFr) is expressed in human bronchial epithelial cells, and non-small cell lung cancers express increased EGFr. Squamous metaplasia of the bronchial epithelium occurs in chronic smokers and is considered an early premalignant change. In this study, EGFr expression was examined in biopsies of histologically normal and metaplastic bronchial tissues obtained from 69 smokers who were enrolled in a randomized placebo-controlled chemoprevention trial. This trial tested the effects of 6 months of treatment with 13-cis retinoic acid (13cRA) on bronchial metaplasia. EGFr expression was examined as a marker of bronchial metaplasia and response to 13cRA treatment. In bronchial biopsies obtained from patients in this study, EGFr expression was higher in metaplastic biopsies than in normal biopsies (P = 0.02). Smoking cessation during treatment correlated with reduced metaplasia (P < 0.001) and EGFr expression (P = 0.02), but multivariate analysis suggested that this effect of smoking cessation on EGFr expression was dependent upon reversal of bronchial metaplasia. 13cRA treatment did not alter EGFr expression (P = 0.23). Baseline EGFr expression levels in metaplastic biopsies did not predict metaplasia reversal. This study demonstrated that increased EGFr expression is a biomarker of bronchial metaplasia, but it did not support the hypothesis that EGFr is a biomarker of retinoid response in lung cancer chemoprevention trials.     

Inhibition of parietal cell acid secretion is mediated by the classical epidermal growth factor receptor

Epidermal growth factor (EGF) and transforming growth factor-alpha (TGF-alpha) inhibit gastric acid secretion both in vivo and in vitro. Previous studies have indicated that EGF and TGF-alpha bind to the same EGF/TGF-alpha receptor. Nevertheless, we and others have previously demonstrated that inhibition of acid secretion by these growth factors requires concentrations of the peptides that are 10-fold higher than those necessary for induction of mitogenesis. Therefore, we have sought to investigate whether gastric parietal cells may possess a second EGF/TGF-alpha receptor class. Two systems were studied: First, [125I]TGF-alpha was cross-linked to the receptor in isolated rabbit parietal cell membranes, and labeled species were resolved on SDS-PAGE. Second, acid secretion was evaluated in pylorus-ligated waved-2 mutant mice, which carry a disabling point mutation in their classical EGF/TGF-alpha receptor. In isolated parietal cells, [125I]TGF-alpha was cross-linked into a single species of 170 kDa. Cross-linking was inhibited in the presence of unlabeled TGF-alpha with an IC50 of 80 nM. In the pylorus-ligated mice, control littermate mice demonstrated a dose-dependent inhibition of acid secretion by EGF with an IC50 of 20 micrograms/kg. In contrast, EGF had no inhibitory effect on acid secretion in waved-2 mice at concentrations up to 100 micrograms/kg. No alterations in parietal cell or gastrin cell numbers were observed. These results in both isolated rabbit parietal cells and waved-2 mice support the existence of only a single class of EGF/TGF-alpha receptors in parietal cells. Differences in growth factor affinity are likely due to the modification of the receptor or one of its coordinate regulators.     

Up-regulation by progesterone of proliferating cell nuclear antigen and epidermal growth factor expression in human uterine leiomyoma

Uterine leiomyoma is the most common smooth muscle cell tumor of the myometrium. Estrogen and progesterone (P4) are believed to be physiological regulators of leiomyoma growth. We recently showed that Bcl-2 protein, an apoptosis-inhibiting gene product, was abundantly expressed in leiomyoma relative to its expression in the normal myometrium and that Bcl-2 protein expression in cultured leiomyoma cells was up-regulated by P4, but down-regulated by 17 beta-estradiol (E2). To further characterize the molecular mechanism of sex steroidal regulation of leiomyoma growth, we examined the effect of menstrual phase on proliferating cell nuclear antigen (PCNA) expression in leiomyoma and investigated whether sex steroids could influence PCNA expression in leiomyoma cells cultured under serum-free conditions by immunoblot and immunohistochemical analyses. As epidermal growth factor (EGF) has been shown to mediate estrogen action and to play a crucial role in regulating leiomyoma growth, we also investigated the effects of sex steroids on the expression of EGF and EGF receptor (EGF-R) in cultured leiomyoma cells. The PCNA labeling index in leiomyomas was much greater in the secretory, P4-dominated, phase than in the proliferative phase of the menstrual cycle and was significantly higher than that in the adjacent normal myometrium throughout the menstrual cycle. In monolayer cultures of leiomyoma cells, the addition of either E2 (10 ng/mL) or P4 (100 ng/mL) resulted in an increase in PCNA expression in the cells compared to that in control cultures, whereas in monolayer cultures of myometrial cells, the addition of E2 augmented PCNA expression in the cells, but P4 did not. Immunoblot analysis of proteins extracted from cultured leiomyoma cells revealed that leiomyoma cells contained immunoreactive EGF with a molecular mass of 133 kDa and that the addition of P4 resulted in a remarkable increase in the expression of 133- and 71-kDa immunoreactive EGF in the cells compared to that in control cultures, whereas the addition of E2 resulted in a somewhat lower expression of immunoreactive EGF in the cells. Furthermore, immunocytochemical analysis with a monoclonal antibody to human EGF-R demonstrated that the treatment with E2 augmented EGF-R expression in the cells compared to that in untreated cells, but P4 did not. The concentrations of sex steroids used were within the physiological tissue concentrations found in leiomyomas and myometria. These results indicate that P4 up-regulates the expression of PCNA and immunoreactive EGF in leiomyoma cells, whereas E2 up-regulates the expression of PCNA and EGF-R in those cells. As it is evident that EGF plays a crucial role as a local factor in regulating leiomyoma growth, the P4-induced increase in PCNA expression in leiomyoma cells may be mediated by P4-induced enhanced expression of EGF-like proteins in the cells, whereas the E2-induced increase in PCNA expression in leiomyoma cells may be mediated by E2-induced enhanced expression of EGF-R in those cells. It is, therefore, conceivable that P4 and E2 act in combination to stimulate the proliferative potential of leiomyoma cells through the induction of EGF-like proteins and EGF-R expression in uterine leiomyoma.