Kirsten ras mutations in patients with colorectal cancer: the 'RASCAL II' study

Researchers worldwide with information about the Kirsten ras (Ki-ras) tumour genotype and outcome of patients with colorectal cancer were invited to provide that data in a schematized format for inclusion in a collaborative database called RASCAL (The Kirsten ras in-colorectal-cancer collaborative group). Our results from 2721 such patients have been presented previously and for the first time in any common cancer, showed conclusively that different gene mutations have different impacts on outcome, even when the mutations occur at the same site on the genome. To explore the effect of Ki-ras mutations at different stages of colorectal cancer, more patients were recruited to the database, which was reanalysed when information on 4268 patients from 42 centres in 21 countries had been entered. After predetermined exclusion criteria were applied, data on 3439 patients were entered into a multivariate analysis. This found that of the 12 possible mutations on codons 12 and 13 of Kirsten ras, only one mutation on codon 12, glycine to valine, found in 8.6% of all patients, had a statistically significant impact on failure-free survival (P = 0.004, HR 1.3) and overall survival (P = 0.008, HR 1.29). This mutation appeared to have a greater impact on outcome in Dukes' C cancers (failure-free survival, P = 0.008, HR 1.5; overall survival P = 0.02, HR 1.45) than in Dukes' B tumours (failure-free survival, P = 0.46, HR 1.12; overall survival P = 0.36, HR 1.15). Ki-ras mutations may occur early in the development of pre-cancerous adenomas in the colon and rectum. However, this collaborative study suggests that not only is the presence of a codon 12 glycine to valine mutation important for cancer progression but also that it may predispose to more aggressive biological behaviour in patients with advanced colorectal cancer.

Endometrial angiogenesis throughout the human menstrual cycle

BACKGROUND

The timing and mechanisms of new blood vessel formation in the endometrium during the menstrual cycle are still largely unknown. In the present study we used the chick embryo chorioallantoic membrane (CAM) as an in-vivo assay for angiogenesis to assess the angiogenic potential of endometrium obtained at different stages of the menstrual cycle.

METHODS

Endometrial fragments were explanted onto the CAM and, after 4 days of incubation, slides of the treated area were taken in ovo through a microscope for computerized image analysis. The vascular density index (VDI), a stereological estimate of vessel number and length, was obtained by counting the intersections of vessels with five concentric circles of a circular grid superimposed on the computerized image.

RESULTS

We demonstrated that human endometrium has angiogenic potential throughout the menstrual cycle. Furthermore, there was a significant difference in angiogenic response between the stages of the menstrual cycle (P = 0.01). The VDIs of the early proliferative, early and late secretory stage were significantly higher than the VDI of the late proliferative phase.

CONCLUSIONS

Elongation of existing vessels during the early proliferative phase as well as growth and coiling of the spiral vessels during the secretory phase may demand far higher angiogenic activity than outgrowth and maintenance of vessels during the late proliferative phase.

The Mesothelium, Teflon or Velcro? Mesothelium in endometriosis pathogenesis

Sampson's transplantation theory for the pathogenesis of peritoneal endometriosis is widely accepted. The events that take place, however, on the cellular and subcellular level during the transition of endometrial tissue in the abdominal cavity into peritoneal endometriosis remain controversial. The mesothelium plays a central role in the debate on this subject. The interaction between endometrium and peritoneum has been studied in an in-vitro model using amnion, peritoneum and mesothelial cells in culture on the one hand and cyclic and menstrual endometrium on the other hand. The results of these studies indicate that (i) an intact mesothelial lining prevents adhesion of shed endometrial tissue, (ii) shed endometrial tissue adheres to the peritoneal extracellular matrix and (iii) menstrual effluent creates its own adhesion sites by damaging the mesothelial lining thus exposing the extracellular matrix. Therefore we conclude that the mesothelium has the properties of Teflon, while the extracellular matrix resembles Velcro.

Development of endometriosis-like lesions after transplantation of human endometrial fragments onto the chick embryo chorioallantoic membrane

The chick embryo chorioallantoic membrane (CAM) bioassay was used to investigate the early pathogenesis of endometriosis. Endometrial fragments were explanted onto the CAM. The grafts including the surrounding CAM were excised at 24, 48 or 72 h after explantation, fixed and embedded in paraffin. Immunohistochemical analysis was used to distinguish endometrial cells. To identify cells of human origin, in-situ hybridization was performed using a probe specific for human chromosome 1. After 24 h, direct contact between endometrial stromal as well as epithelial cells and the mesenchymal layer of the CAM was observed. Invasion of both stromal cells and intact endometrial glands into the mesenchymal layer was observed after 48 h. At 72 h, endometriosis-like lesions were observed in the mesenchymal layer. Positive staining with antibodies to vimentin and pan-cytokeratin was observed in the invading cells as well as in the lesions. In the lesions these positively stained cells showed in-situ hybridization signals for human chromosome 1, confirming their human origin. In conclusion, after 3 days of incubation, endometriosis-like lesions consisting of human endometrial glands and stromal cells were found in the mesenchymal layer of the CAM. These lesions apparently resulted from the invasion of intact human epithelial structures and stromal cells.

Molecular genetic alterations in hamartomatous polyps and carcinomas of patients with Peutz-Jeghers syndrome

AIM

To investigate whether mutations in the STK11/LKB1 gene and genes implicated in the colorectal adenoma-carcinoma sequence are involved in Peutz-Jeghers syndrome (PJS) related tumorigenesis.

METHODS

Thirty nine polyps and five carcinomas from 17 patients (from 13 families) with PJS were analysed for loss of heterozygosity (LOH) at 19p13.3 (STK11/LKB1 gene locus), 5q21 (APC gene locus), 18q21-22 (Smad4 and Smad2 gene locus), and 17p13 (p53 gene locus), and evaluated for immunohistochemical staining of p53. In addition, mutational analysis of K-ras codon 12, APC, and p53 and immunohistochemistry for Smad4 expression were performed on all carcinomas.

RESULTS

LOH at 19p was seen in 15 of the 39 polyps and in all carcinomas (n = 5). Interestingly, six of the seven polyps from patients with cancer had LOH, compared with nine of the 31 polyps from the remaining patients (p = 0.01). In one polyp from a patient without a germline STK11/LKB1 mutation, no LOH at 19p or at three alternative PJS candidate loci (19q, 6p, and 6q) was found. No LOH at 5q was observed. However, mutational analysis revealed an APC mutation in four of the five carcinomas. LOH at 17p was not seen in polyps or carcinomas; immunohistochemistry showed expression of p53 in one carcinoma and focal expression in three polyps. At subsequent sequence analysis, no p53 mutation was found. One carcinoma had an activating K-ras codon 12 mutation and another carcinoma showed 18q LOH; however, no loss of Smad4 expression was seen.

CONCLUSIONS

These results provide further evidence that STK11/LKB1 acts as a tumour suppressor gene, and may be involved in the early stages of PJS tumorigenesis. Further research is needed to see whether LOH in PJS polyps could be used as a biomarker to predict cancer. Differences in molecular genetic alterations noted between the adenoma-carcinoma sequence and PJS related tumours suggest the presence of a distinct pathway of carcinogenesis.

Tumor necrosis factor-alpha but not interleukin-1 beta or interleukin-8 concentrations correlate with angiogenic activity of peritoneal fluid from patients with minimal to mild endometriosis

OBJECTIVE

To assess the angiogenic activity of peritoneal fluid in women with minimal to mild endometriosis and to investigate the relationship between this activity and the concentration of macrophage-derived angiogenic factors and clinical variables, such as phase of menstrual cycle, type of lesion, and revised American Society for Reproductive Medicine classification.

DESIGN

In vivo bioassay.

SETTING

Tertiary-care university medical center.

PATIENT(S)

Fifty-two female volunteers with laparoscopic findings indicating minimal to mild endometriosis.

INTERVENTION(S)

Peritoneal fluid was collected at the start of laparoscopy. A standard amount of peritoneal fluid was applied to a chick embryo chorioallantoic membrane assay.

MAIN OUTCOME MEASURE(S)

Angiogenic response was assessed by determining the vascular density index.

RESULT(S)

85% of the peritoneal fluid samples induced angiogenesis in the chick embryo chorioallantoic membrane bioassay. Tumor necrosis factor-alpha and total protein were significantly related to the vascular density index, whereas interleukin-1beta, interleukin-8, and clinical variables appeared to not affect the angiogenic response.

CONCLUSION(S)

The results confirms previous findings of peritoneal fluid angiogenic activity in women with minimal to mild endometriosis and indicate involvement of tumor necrosis factor-alpha.

Amniotic membrane as an in vitro model for endometrium-extracellular matrix interactions

The aim of the study was to develop an in vitro model to study the interaction between endometrial cells and extracellular matrix (ECM) and to evaluate the expression of cell adhesion molecules in endometrial cells and tissue fragments under in vitro conditions. Endometrial biopsies were collected from 32 patients. Samples were either digested using collagenase type I, or dissected mechanically. Adhesion of isolated cells and tissue fragments to stripped amniotic membranes and to coverslips coated with ECM components was studied. The expression of beta1 integrins and cadherins was assessed using immunohistochemistry. Collagenase digestion of endometrial biopsies yielded viable single cells. These cells did not adhere to either side of stripped amniotic membranes, and did not show expression of the cell adhesion molecules. In contrast, mechanically fragmented endometrium samples adhered to both sides of stripped amniotic membranes and showed immunohistochemical expression of E- and P-cadherin and integrin subunits alpha2, alpha3, alpha4, alpha5 and alpha6. Amniotic membranes, after stripping of epithelial lining, are suitable to study interactions between endometrial tissue and ECM in functional and structural studies. Endometrial cells after collagenase type I digestion do not adhere to stripped amniotic membrane and have lost expression of beta1 integrins and E- and P-cadherin.

Menstruum induces changes in mesothelial cell morphology

In previous studies, we have shown that menstrual endometrium preferentially adheres to the subepithelial lining of the peritoneum. It remains to be elucidated, however, whether this damage is preexisting or inflicted by the menstrual tissue itself. We hypothesized that the menstrual tissue itself damages the peritoneum. To investigate this, the viability of menstrual endometrial tissue in peritoneal fluid (PF) was evaluated and the morphologic changes in the mesothelial cells were studied by in vitro cocultures of menstruum with mesothelial cell monolayers. Menstruum was collected with a menstrual cup. Endometrial tissue was isolated from the menstruum, resuspended in culture medium or in the cell-free fraction of PF and cultured for 24, 48 or 72 h. A 3(4, 5-dimethylthiazolyl-2)-2,5-diphenyl tetrazolium bromide (MTT) assay was performed to obtain a relative measure of viable adhered endometrial cells. Mesothelial cells isolated from human omental tissue were cultured on Matrigel or uncoated plastic. At confluence, overnight cocultures were performed and scanning electron microscopy was used to evaluate the morphologic changes. The viability of endometrial fragments was 84% (n = 36, p < 0.05), 82% (n = 27, not significant) and 104% (n = 14, not significant) when cultured in the cell-free fraction of PF for 24, 48 and 72 h, respectively, when compared to medium with 10% fetal calf serum. Menstrual endometrial fragments or menstrual serum added to and cocultured with mesothelial cells induced severe morphologic alterations of the latter, including retraction, shrinking and gap formation. Similar morphologic changes were observed when mesothelial cells were cocultured with menstrual endometrial fragments in PF or in culture inserts. Incubation with conditioned medium from cultured menstrual endometrium induced similar but less pronounced changes in morphology. In conclusion, menstrual endometrial fragments remain viable in PF in vitro for at least 72 h. Antegradely shed menstruum induces changes in mesothelial cell morphology, including retraction and shrinking with exposure of the underlying surface. These findings suggest that menstruum is harmful to the peritoneal lining. Therefore, by local destruction of the mesothelial layer, menstrual endometrium is able to create sites for adhesion.

Morphological changes in mesothelial cells induced by shed menstrual endometrium in vitro are not primarily due to apoptosis or necrosis

In a previous study on the pathogenesis of endometriosis, we observed that constituents of menstrual effluent induce morphological alterations in human mesothelial cells. In this study, we investigated whether these alterations were associated with apoptosis or necrosis or were the result of cellular remodelling. After overnight incubation of confluent monolayers of human omental mesothelial cells (HOMEC) with conditioned media prepared from menstrual effluent shed anterogradely, severe alterations in morphology were observed. Typical polygonal mesothelial cell cultures at confluency acquired elongated spindle morphology, resulting in gaps between the cells. In contrast, mesothelial cells from the control groups receiving culture medium only, retained a normal morphology. Immunofluorescence staining revealed that cytokeratin, vimentin and actin filaments were still present, homogeneously distributed in the cell cytoplasm following changes in morphology. To evaluate whether the morphological alterations were associated with apoptosis and/or necrosis, the cells were stained with the M30 CytoDeath antibody or annexin V with propidium iodide and analysed using flow cytometry. The results showed that only a small percentage (1-7%) of the affected HOMEC were undergoing apoptosis or necrosis. We conclude that the profoundly altered morphology of HOMEC is a result of cellular remodelling and that the role of apoptosis and necrosis is negligible. Soluble paracrine factors released by cells isolated from menstrual effluent shed anterogradely may induce a reorganization of the cytoskeleton. As a result, the underlying basement membrane will be exposed and the mesothelium may no longer prevent implantation of endometrium shed retrogradely into the peritoneum, thus facilitating the development of endometriosis.

Matrix metalloproteinases and their tissue inhibitors in antegradely shed menstruum and peritoneal fluid

OBJECTIVE

To investigate the expression of matrix metalloproteinases (MMPs) and their tissue inhibitors (TIMPs) in antegradely shed menstruum and peritoneal fluid.

DESIGN

A cell biological and immunohistochemical study.

SETTING

Tertiary care university medical center.

INTERVENTION(S)

Immunohistochemistry was performed on cryostat sections and cultures of menstrual endometrium. Zymography was used to characterize MMP activity in peritoneal fluid, in menstrual serum, and in conditioned medium. Western blot analysis was used to further identify the MMPs in these fluids.

MAIN OUTCOME MEASURE(S)

Staining of MMPs and TIMPs in cryostat sections and cultures and MMP expression and activity in peritoneal fluid and menstrual blood serum.

RESULT(S)

Strong staining for MMP-1 and MMP-3 was observed in stroma and for MMP-7 in epithelium. Matrix metalloproteinase-2 and MMP-9 were weakly expressed in stroma. Both TIMP-1 and TIMP-2 were expressed in menstrual endometrium. Menstrual serum showed a pattern of MMP activity on zymography different from peritoneal fluid. Western blot analysis showed the presence of MMP-7 and MMP-9 in menstrual serum.

CONCLUSION(S)

Antegradely shed menstrual endometrium expresses several MMPs and TIMPs, even after culturing for 24 hours. MMP activity in menstrual serum is different from and more intense than MMP activity in peritoneal fluid. These enzymes may be involved in the early invasion of menstrual endometrium into the extracellular matrix of the peritoneum.

Adhesion of menstrual endometrium to extracellular matrix: the possible role of integrin alpha(6)beta(1) and laminin interaction

Previous in-vitro studies have shown that the endometrium preferentially adheres to the extracellular matrix (ECM) of the amnion and peritoneum. This interaction probably involves adhesion molecules, e.g. integrins. We evaluated the expression of integrins in naturally shed menstrual endometrium and the adhesion pattern of this tissue to different components of the ECM. To identify integrins and matrix components involved, blocking studies were performed. Most of the 15 menstrual tissue samples showed positive staining for each of the integrins investigated, except alpha(4)beta(1). Compared with binding to collagen IV, which was set at 100%, adhesion to collagen I was 93% (not significant), to fibronectin 87% (P < 0.05), and to laminin 74% (P < 0.05). Scanning electron micoscopy showed that endometrium adhered to laminin but hardly spread, whereas spreading was observed when layered on the other coatings. Compared with the control (which was set at 100%), incubation with 4B4, a monoclonal antibody against the integrin beta(1) subunit, showed a significant reduction of adhesion (to approximately 50%; P < 0.05) when layered on laminin and a smaller reduction (to 82-86%; P < 0.05) when layered on the other three coatings. Incubation with antibody GOH3 against integrin alpha(6)beta(1) resulted in a similar reduction in adhesion to laminin. Incubation with an RGD peptide significantly reduced adhesion (to 84%; P < 0.05) when plated on fibronectin. In conclusion, antegradely shed menstrual endometrium expresses various integrins. It shows preferential attachment to collagen IV and collagen I, when compared with fibronectin and laminin. Blockage of the integrin beta(1) subunit resulted in greatest disruption to adhesion when layered on laminin, implying that the interaction was mediated by the alpha(6)beta(1) integrin. Since this adhesion was not completely blocked, other mechanisms are likely to be involved.

The chick embryo chorioallantoic membrane as a model to investigate the angiogenic properties of human endometrium

The chick embryo chorioallantoic membrane (CAM) is an established in vivo angiogenesis assay. The aim of our study was to assess the angiogenic properties of endometrium and to quantitate the vascular response in an accurate way. Samples of proliferative endometrium (n = 17) and control mouse skin tissue (n = 8) were explanted onto the CAM at day 10 of incubation. Additional controls consisted of normal unmanipulated CAM (n = 12). Four days after grafting, photographs of the explant and the surrounding area were taken in ovo to measure the vascular density index (VDI). The VDI is a stereological estimate of vessel number and length, which was obtained by counting the intersections of vessels with a circular grid superimposed on a computerized image. Endometrium caused a significant increase in VDI as compared to both unmanipulated CAM (p < 0.001) and skin tissue as a control (p < 0.007). The intra-observer variability was 5.2%. This study demonstrates that the CAM assay is a suitable model to assess the angiogenic properties of endometrium. Furthermore, it allows detailed quantitation of the vascular response in an objective and reproducible way. Our findings suggest the CAM to be a promising model to study the role of angiogenesis in both normal human endometrium and diseases involving the endometrium.

Adhesion of human endometrial fragments to peritoneum in vitro

OBJECTIVE

To evaluate the adhesion of endometrial fragments obtained during the proliferative phase of the menstrual cycle to fresh human peritoneum obtained during abdominal surgery.

DESIGN

A prospective, descriptive, morphologic and cell biologic study.

SETTING

Tertiary care university medical center.

PATIENT(S)

Six female volunteers.

INTERVENTION(S)

After endometrial biopsies performed during diagnostic laparoscopy, endometrial fragments were generated by enzymatic digestion and mechanical separation. Peritoneum was obtained during abdominal operations for benign indications.

MAIN OUTCOME MEASURE(S)

Adhesion of endometrial fragments was studied by histologic examination and scanning and transmission electron microscopy.

RESULT(S)

After incubation, the mesothelium was intact in some areas, whereas in other areas mesothelial cells were damaged or absent. Adhesion of endometrial fragments was observed only at locations where the basement membrane was exposed. In areas largely denuded of mesothelial cells, endometrial fragments spread over the basement membrane to form monolayers.

CONCLUSION(S)

Human peritoneum is suitable for studying the adhesion of endometrial fragments. Intact mesothelium prevents the adhesion of endometrial fragments, suggesting that trauma to the mesothelial lining is a prerequisite for endometrial cell adhesion.

Adhesion of shed menstrual tissue in an in-vitro model using amnion and peritoneum: a light and electron microscopic study

We have investigated the adhesion of endometrial tissue isolated from antegradely shed menstrual effluent to amnion and peritoneum. This endometrial tissue was cultured overnight on either side of intact and stripped amnion and on the mesothelial side of peritoneum. Light and electron microscopy were applied to evaluate adhesion. With light microscopy adhesion of endometrial fragments to stripped membranes was observed in nine out of 12 specimens and in 12 out of 13 specimens when layered on the extracellular matrix side of amnion. Adhesion when layered on the epithelial side was seen in only four out of 13 specimens. However, when using scanning electron microscopy adhesion of menstrual endometrial tissue could be visualized in all samples. Numerous adhering fragments were seen when layered on the extracellular matrix side of untreated amnion. On several occasions not only adhesion but also spreading of cells was observed. When layered on the epithelial side of untreated amnion or peritoneum, adhesion was exclusively seen at locations where the epithelium was damaged or absent. These findings were confirmed by transmission electron microscopy. These observations indicate that endometrial tissue isolated from antegradely shed menstrual effluent preferentially adheres to subepithelial structures of amnion and peritoneum. The lack of adhesion to epithelial cells suggests that an intact mesothelial lining prevents adhesion of menstrual endometrial tissue.

Adhesion of human endometrium to the epithelial lining and extracellular matrix of amnion in vitro: an electron microscopic study

One of the first steps in the pathogenesis of endometriosis is the attachment of the endometrium to the peritoneal lining. Since the peritoneum is extremely fragile and hard to obtain, amnion has been used as an in-vitro model to study adhesion. Scanning and transmission electron microscopy was applied to evaluate the adhesion of endometrial cells isolated in the proliferative and secretory phases of the menstrual cycle. Endometrial fragments obtained in either phase of the cycle were able to adhere to the extracellular matrix of the amnion. Fragments from proliferative phase endometrium showed active spreading and growth over the matrix surface, whereas fragments from secretory phase endometrium did not. Fragments from proliferative as well as secretory phase endometrium were able to adhere to the epithelial side of the amnion, but only at locations where the amniotic epithelium was damaged or partly absent. These observations indicate that the basement membrane and extracellular matrix provide a suitable substrate for endometrial cell attachment and growth and that endometrial cell adhesion occurs preferentially to subepithelial structures, whereas an intact epithelium prevents the adhesion of endometrial fragments to the amnion.

Evaluation of a menstrual cup to collect shed endometrium for in vitro studies

OBJECTIVE

To evaluate whether a menstrual cup is a suitable instrument to collect antegradely shed endometrium for in vitro studies.

DESIGN

A prospective, descriptive, cell biological and immunohistochemical study.

SETTING

Tertiary care university medical center.

PATIENT(S)

Nine female volunteers with regular cycles.

INTERVENTION(S)

Menstrual effluent was collected with a menstrual cup. Experience with the menstrual cup was described. Cytospin specimens, frozen sections, and cultures were prepared from the obtained menstrual tissue.

MAIN OUTCOME MEASURE(S)

The acceptability of the menstrual cup. The presence and viability of endometrial tissue was evaluated using immunohistochemical staining and culture outcome.

RESULT(S)

All women except one described the menstrual cup as acceptable. Menstrual effluent contained single cells, clumps of cells, and glandlike structures. After 5 days of culture, the endometrial tissue appeared to be viable. Immunohistochemistry showed positive staining for vimentin in most cytospin specimens, in all cryostat specimens, and in 10 of 17 cultures. Cytokeratin 18 stained most cytospin specimens, all cryostat specimens, and 10 of 17 cultures. Positive staining for BW495/36 was observed in most cytospin specimens, all cryostat specimens, and 11 of 17 cultures.

CONCLUSION

A menstrual cup in an acceptable instrument to collect antegradely shed menstrual tissue. Menstruum contains viable endometrial tissue that can be used for in vitro studies of endometrium and endometriosis.

Endometrial cell adhesion in an in vitro model using intact amniotic membranes

OBJECTIVE

To study adhesion between endometrial tissue and peritoneum using intact amniotic membranes as an in vitro model.

DESIGN

A cell biologic and immunohistochemical study.

SETTING

Tertiary-care university medical center.

PATIENTS

Ten patients with regular and ovulatory cycles.

INTERVENTIONS

Mechanically dissected tissue fragments from endometrial biopsies were cultured on either side of intact amniotic membranes. Also, the carcinoma cell lines RL95-2 and AN3CA were used.

MAIN OUTCOME MEASURES

The adhesion of endometrial fragments and of endometrial carcinoma cell lines to amniotic membrane was studied in vitro and evaluated using frozen sections. The composition of the extracellular matrix and the presence of intermediate filament proteins of amniotic membrane were determined using immunohistochemistry and compared with those of normal peritoneum.

RESULTS

Peritoneum and amniotic membrane were similar with respect to expression of cytokeratins in epithelial lining and of extracellular matrix (ECM) components. The endometrial fragments did not adhere to the intact epithelial side of the amniotic membrane. In contrast, adhesion did occur to the nonepithelial side of the amnion. The carcinoma cell lines RL95-2 and AN3CA adhered to either side of intact amniotic membranes.

CONCLUSIONS

An intact epithelial lining prevents adhesion of endometrial fragments to the ECM of amniotic membranes in vitro. An intact epithelium could be important defense mechanism in preventing initial adhesion of retrogradely shed endometrium fragments to peritoneum.

Epithelial cells in peritoneal fluid--of endometrial origin?

OBJECTIVE

Our purpose was to examine the immunohistochemical properties of epithelial cells in peritoneal fluid and to compare the staining characteristics with cells of endometrium, menstrual effluent, peritoneum, and endometriotic lesions.

STUDY DESIGN

Samples of menstrual effluent, endometrium, and peritoneal fluid and biopsy specimens of endometriotic lesions and peritoneum from 16 patients were examined. Monoclonal antibodies against vimentin, cytokeratin 18 and 19, and the monoclonal antibody BW495/36, staining an epithelial marker present in endometrium and absent in peritoneal epithelium, were used.

RESULTS

All but one sample of menstrual effluent and peritoneal fluid cells stained positively with antibodies against vimentin and cytokeratin 18 and 19. BW495/36 stained 14 of 16 menstrual effluent samples and nine of 16 peritoneal fluid cell samples. Endometriotic specimens showed staining with all markers. No major differences in staining properties were observed in menstrual effluent, endometrium, and peritoneal fluid cells between patients with or without endometriosis.

CONCLUSION

These results support the contention of transport of menstrual detritus to the peritoneal cavity in women with patent fallopian tubes.

Expression of cadherins and integrins in human endometrium throughout the menstrual cycle

OBJECTIVE

To detect cadherin and integrin expression in biopsies of endometrium in the phases of the cycle. Cell adhesion molecules may be involved in endometrial shedding during menstruation and attachment of shed endometrial tissue to the peritoneal lining in endometriosis patients.

DESIGN

An immunohistochemical study on fresh frozen sections.

SETTING

Tertiary-care university medical center.

PATIENTS

Sixteen patients undergoing monitoring of their cycle as part of a subfertility workup. All patients had regular and ovulatory cycles.

INTERVENTIONS

Endometrium samples were obtained at well-defined phases of the cycle. Simultaneously, blood samples were collected for E2 and P assay.

MAIN OUTCOME MEASURES

The expression of cell adhesion molecules, including E- and P-cadherin and the integrins alpha 2 beta 1, alpha 3 beta 1, alpha 4 beta 1, alpha 5 beta 1, and alpha 6 beta 1, and the expression of estrogen receptor (ER) and P receptor (PR).

RESULTS

E- and P-cadherin expression was demonstrated in all endometrium samples. Integrins alpha 3 beta 1, alpha 4 beta 1, alpha 5 beta 1, and alpha 6 beta 1 were detected in samples from all cycle phases, whereas integrin alpha 2 beta 1 was not detected in midluteal samples. The serum levels of E2 were 24.7 pg/mL (range: 10.9 to 35.4 pg/mL) in the early follicular phase and 190.7 pg/mL (range: 152.5 to 256.1 pg/mL) in the preovulatory phase (conversion factor to SI unit, 3.671). Serum P was 13.7 ng/mL (range: 10.3 to 16.7 ng/mL) in the midluteal phase and 6.4 ng/mL (range: 1.2 to 13.7 ng/mL) in the premenstrual phase (conversion factor to SI unit, 3.180). The portion of cells staining for ER and PR was at a maximum during the preovulatory phase, both for epithelial and stromal cells.

CONCLUSIONS

E- and P-cadherin expression was detected in all samples and did not vary throughout the menstrual cycle. If their expression is involved functionally in the cyclic menstrual shedding, the loss of expression is limited to a short period of time. Of the beta 1 integrins, only alpha 2 beta 1 expression was modulated during the menstrual cycle and found to be absent in the midluteal phase. No relation was found between the expression of cell adhesion molecules and the expression of ER and PR. Because the cadherins and beta 1 integrins could be detected in late luteal phase endometrium, these cell adhesion molecules could be involved in the attachment of endometrial fragments to the peritoneal lining as a result of retrograde menstruation. The potential function in the pathogenesis of endometriosis remains to be elucidated.

P-cadherin expression in human endometrium and endometriosis

The objective of the present study was to detect the expression of P-cadherin in human endometrium and endometriosis and to compare this expression to that of E-cadherin. To this end immunohistochemistry with monoclonal antibodies specific for P-cadherin and E-cadherin was applied to endometrium and endometriotic lesions obtained in the early follicular phase of the menstrual cycle from 10 patients. P-cadherin was detected in epithelial cells in all ten endometrial samples and in all glandular structures of endometriotic lesions. The staining characteristics for P-cadherin and E-cadherin were similar. P-cadherin may play a role in the maintenance of the proliferative compartment of endometrium and could have a comparable function in endometriotic lesions.

Expression of integrins and E-cadherin in cells from menstrual effluent, endometrium, peritoneal fluid, peritoneum, and endometriosis

OBJECTIVE

To detect the expression of integrins and E-cadherin in cells from peritoneal fluid (PF), endometrium, menstrual effluent, peritoneum, and endometriotic lesions during the early follicular phase of the menstrual cycle.

DESIGN

An immunohistochemical study.

SETTING

Tertiary care university medical center.

PATIENTS

Sixteen patients undergoing a diagnostic laparoscopy as part of a subfertility work-up. All patients had regular and ovulatory cycles.

INTERVENTIONS

A laparoscopy was performed in the early follicular phase (days 2 to 5). Simultaneously, samples were taken from endometrium, menstrual effluent, and PF, and a representative biopsy of an endometriotic lesion was obtained. If endometriosis was not noted, a peritoneal biopsy was obtained instead.

MAIN OUTCOME MEASURES

The expression of cell adhesion molecules, including the integrin alpha 2 beta 1, alpha 3 beta 1, alpha 4 beta 1, alpha 5 beta 1, and alpha 6 beta 1 and E-cadherin, as determined by immunohistochemistry on frozen sections.

RESULTS

All integrins tested could be detected in the endometrium samples and in endometriotic lesions. In menstrual effluent samples, positive staining for the integrins alpha 2 beta 1 and alpha 3 beta 1 was found in epithelial cells in 13 of 16 cases. Integrin alpha 5 beta 1 was detected in 11 of 16 samples, and integrins alpha 4 beta 1 and alpha 6 beta 1 were detected in 5 of 16 samples. In PF, integrin alpha 3 beta 1 was found in epithelial cells in 12 of 16 samples, integrin alpha 5 beta 1 in 5 of 16, and integrins alpha 4 beta 1 in 2 of 16. The antibody for E-cadherin showed positive staining of epithelial cells in 6 of 16 menstrual effluent samples. All endometrial tissue samples showed positive staining for E-cadherin. In PF, E-cadherin was detected in the epithelial cells of one sample. One peritoneum biopsy revealed positive staining for E-cadherin.

CONCLUSION

Integrins alpha 2 beta 1, alpha 3 beta 1, alpha 4 beta 1, alpha 5 beta 1, and E-cadherin, important cell adhesion molecules, are expressed in endometriotic lesions and in cells and tissues that are potentially involved in the development of endometriosis. These cell adhesion molecules could be involved in the shedding of endometrial tissue during menstruation and the attachment of endometrial tissue fragments to the peritoneum.

K-ras point mutations in routinely processed tissues: non-radioactive screening by single strand conformational polymorphism analysis

AIMS

To develop a non-radioactive method to screen routinely fixed, paraffin wax embedded specimens for the occurrence of point mutations; to evaluate the single strand conformational polymorphism (SSCP) analysis technique for the detection of K-ras point mutations as a result of electrophoretic mobility shifts.

METHODS

DNA was extracted from archival specimens of colon cancer and from established colon cancer cell lines with known point mutations. A K-ras gene fragment containing codons 12 and 13 of exon 1 was amplified with the polymerase chain reaction (PCR). Denatured DNA fragments were run on 10% polyacrylamide gels under non-denaturing conditions. After electrophoresis DNA was blotted and the single stranded DNA was detected using a digoxigenin labelled ras probe. The nature of the detected point mutations was identified and confirmed by sequencing and hybridisation with oligonucleotides using 32P labelling.

RESULTS

Wild type and aberrant alleles were detected caused by mobility shifts after electrophoresis of the PCR products. Commonly occurring mutations in the K-ras gene--in the first two positions of codon 12--could easily be detected in DNA from archival paraffin wax embedded colon cancer tissue. In all the colon tumour samples studied wild type gene alleles were also found, presumably derived from normal cells in the specimen.

CONCLUSIONS

The SSCP method permits rapid non-radioactive screening of adenomas or carcinomas for the occurrence of point mutations in the K-ras gene. But if a mutation is detected by an electrophoretic mobility shift, its identification requires confirmation by sequencing or oligonucleotide hybridisation.

NCI-H716 cells as a model for endocrine differentiation in colorectal cancer

In colonic neoplasms, endocrine differentiation is encountered not only in carcinoid tumors but also in adenocarcinomas, where endocrine cells may represent a distinct line of differentiation in the tumor. The significance of endocrine differentiation in colorectal cancer is not well established, partly because of the paucity of tumor cell lines which can serve as a model for studying endocrine differentiation. In this report we describe the properties of NCI-H716 cells, a cell line derived from a poorly differentiated adenocarcinoma of the caecum, under various in vitro conditions and as xenografts in athymic mice. Phenotypical properties were immunohistochemically assessed using a panel of differentiation related antibodies, and also by Northern blot analysis and by electron microscopy. Receptors for biogenic amines and peptide hormones were analyzed by ligand binding assay. These studies show that: 1. NCI-H716 cells can be undifferentiated, or show endocrine, mucin-producing or "amphicrine" properties. 2. Endocrine differentiation of NCI-H716 cells preferentially occurs in xenografts in athymic mice, which suggests that mesenchymal elements induce endocrine differentiation. 3. NCI-H716 cells express large amounts of high affinity receptors for gastrin, serotonin and somatostatin and these substances can regulate growth. Thus, NCI-H716 cells form a suitable model for the study of endocrine differentiation in intestinal epithelium and of auto- or paracrine growth regulation in intestinal neoplasia.

Immunocytochemical analysis of oestrogen receptors and progesterone receptors in the human uterus throughout the menstrual cycle and after the menopause

To obtain more insight into the relationship between cyclic and regional changes in steroid receptor expression and function-related changes in the various types of cell of the normal human uterus, we performed an immunocytochemical study on paraffin-embedded sections. The distribution and intensity of immunostaining for the oestrogen receptor and the progesterone receptor in the various types of cell were semiquantitatively scored. The data were statistically compared for the different phases of the menstrual cycle and after the menopause, and for the different regions of the corpus and (endo)cervix uteri. During the menstrual cycle, significant changes in oestrogen receptor score were observed in glandular and stromal cells of endometrium basalis and functionalis and in smooth muscle cells of the myometrium. In all types of cell, oestrogen receptor expression reached a maximum in the late proliferative phase. During the early secretory phase, oestrogen receptor staining declined sharply in stromal and smooth muscle cells, whereas, in glandular epithelium, oestrogen receptor expression decreased more gradually. During mid- and late-secretory phases, an increase in oestrogen receptor staining was also observed in predecidualizing stromal cells and smooth muscle cells. Progesterone receptor numbers changed significantly in glandular epithelium but not in stromal and smooth muscle cells. Glandular progesterone receptor expression reached a maximum in the early secretory phase and was then drastically reduced. During mid- and late-secretory phases stromal cells were moderately stained for progesterone receptor in contrast to epithelial gland cells which showed no or very weak staining. No regional variations in steroid receptor distribution in endometrium and myometrium were found.(ABSTRACT TRUNCATED AT 250 WORDS)

Oestrogen and progesterone receptor immunocytochemistry in human hyperplastic and neoplastic endometrium

Proliferative disorders of the endometrium may be associated with autocrine and paracrine actions between stromal and epithelial cells. To determine whether the stromal-epithelial relation with respect to oestrogen receptor (OR) and progesterone receptor (PR) is disturbed in (pre)malignant endometrium immunocytochemical OR and PR expression was quantitated by computerized image analysis. This was studied in the stromal and epithelial cells of endometrial specimens diagnosed as hyperplasia (n = 14), atypical hyperplasia (n = 16), and adenocarcinoma (n = 33). Paraffin sections were used for optimal preservation of histomorphology. A progressive loss of OR and PR content occurred with increasing malignant transformation. Stromal cells in atypical hyperplasia (P = 0.0007) and well-differentiated adenocarcinoma (P = 0.0008) exhibited a relative loss of PR content as compared with epithelial cells (P = 0.036 and P = 0.17, respectively). In atypical hyperplasia, the decrease in stromal PR content was not in parallel with persistent stromal OR immunostaining. Furthermore, stromal PR expression in atypical hyperplasia was significantly (P = 0.004) lower than in the surrounding hyperplasia, whereas the stromal OR staining as well as the epithelial OR and PR staining did not differ significantly. These observations may reflect a disturbance in hormonal interrelationships between endometrial cells in the development of endometrial neoplasia, indicating that stroma may modulate epithelial growth by paracrine mechanisms.

Quality control in immunocytochemistry: experiences with the oestrogen receptor assay

AIMS

To evaluate the feasibility of an interlaboratory quality control programme in immunohistochemistry.

METHODS

Several pathology laboratories were asked to carry out immunohistochemical oestrogen receptor staining on a set of freeze dried cryostat sections of breast cancer tissue. The sections and protocols for staining and semi-quantitative scoring were mailed to the participating laboratories in two trials. The oestrogen receptor content of the breast cancer samples was determined by radioligand binding assay on the tumour cytosol.

RESULTS

In the first trial 11 laboratories (response rate 60%) participated. Eight (73%) of the participants scored within a 95% confidence interval and all but one correctly classified the tumour as receptor positive. In the second trial all 20 participating laboratories (response rate 55%) correctly scored one tumour sample as negative and 18 of them (90% of respondents) correctly classified the two other tumour samples as receptor positive. In a quantitative evaluation a histochemical score within 95% confidence interval limits was provided by eight (40%) and 12 (60%) of the participants.

CONCLUSIONS

Semiquantitative scoring of immunocytochemical staining is valuable for performing correlative inter-laboratory studies, although this scoring protocol may not be required for diagnosis or prognosis. Significant inter-laboratory variability exists, leading to qualitatively correct receptor classification in 100% of receptor negative and 80% of receptor positive cases, and quantitative agreement in only about half of the cases. The perceived variability is not caused by systematic differences in the choice of the immunocytochemical technique, or the mailing of freeze dried sections. Quality control programmes should be included in the standard procedures of each diagnostic immunohistochemistry laboratory.

Southern and dot blot analysis of DNA from formalin-fixed, paraffin-embedded tissue samples from colonic carcinomas

Two extraction methods for the isolation of DNA from formalin-fixed, paraffin-embedded tissue samples from colonic carcinomas were compared. The processed DNAs were compared with DNAs from fresh specimens of the same tumors. The two extraction methods gave similar results. Formalin-fixation and paraffin-embedding irreversibly denatured DNA and consequently decreased the extraction yield and interfered with the quantitative measurement of DNA. Southern blot and dot blot analysis of processed and native DNA was performed using a c-myc and an actin probe. The results show that for Southern analysis processed DNA can be used but, due to the generation of random breaks, the restriction fragments have to be small. Furthermore, the fixation-induced crosslinking of DNA appears to hamper hybridization. For these reasons processed DNA can be analyzed better by dot blot rather than Southern blot hybridization.

Patterns of basement membrane deposition in benign and malignant breast tumours

We have examined epithelial basement membranes in tissue samples of seven normal breasts, 64 benign breast lesions and 63 malignant breast tumours by immunocytochemistry, using polyclonal antisera specific for type IV collagen. In normal breast tissue as well as in all benign tumours a continuous basement membrane was found at the epithelial stromal interface. In benign proliferative lesions, epitheliosis and papillomatosis could be more accurately distinguished with basement membrane staining. This approach also facilitated the differentiation between sclerosing adenosis and tubular carcinoma, since the tubules in sclerosing adenosis are surrounded by a continuous basement membrane whereas in tubular carcinoma basement membranes are almost entirely absent. In radial scar lesions the tubules were always surrounded by intact basement membranes, which underlines the fact that these are benign lesions. In breast carcinoma we could not detect a relationship between histological grade and the extent of basement membrane deposition. However, in different tumour types the basement membrane alterations varied. In infiltrating lobular carcinoma of the alveolar type, fragments of basement membrane were found, whereas in the classic and trabecular type, basement membranes were absent, suggesting that the alveolar type may be an intermediate phase in the progression of lobular carcinoma in situ to infiltrating lobular carcinoma. It is concluded that basement membrane immunocytochemistry, using antibodies to type IV collagen, is useful in the differentiation between benign and malignant breast lesions and in the classification of breast neoplasms.

Photodynamic effects of protoporphyrin on human erythrocytes. Nature of the cross-linking of membrane proteins

Protoporphyrin-sensitized photooxidation in human red blood cell membranes leads to severe deterioration of membrane structure and function. The membrane damage is caused by direct oxidation of amino acid residues, with subsequent cross-linking of membrane proteins. The chemical nature of these cross-links was studied in model systems, isolated spectrin and red cell ghosts. Cysteine and methionine are not involved in the cross-linking reaction. Further it could be shown that dityrosine formation, the crucial mechanism in oxidative cross-linking of proteins by peroxidase-H2O2 treatment, plays no role in photodynamic cross-linking. Experimental evidence indicated that a secondary reaction between free amino groups and a photooxidation product of histidine, tyrosine or tryptophan is involved in photodynamic cross-linking. This was deduced from the reaction observed between compounds containing a free amino group and photooxidation products of these amino acids, both in model systems, isolated spectrin and erythrocyte ghosts. In accordance, succinylation of free amino groups of membrane proteins or addition of compounds with free amino groups protected against cross-linking. Quantitative data and consideration of the reaction mechanisms of photodynamic oxidation of amino acids make it highly probable that an oxidation product of histidine rather than of tyrosine or tryptophan is involved in the cross-linking reaction, via a nucleophilic addition by free amino groups.

Binding of Protoporphyrin to hemoglobin in red blood cells of patients with erythropoietic protoporphyria

Virtually all protoporphyrin in erythrocytes of patients with erythropoietic protoporphyria is bound to hemoglobin. The maximum of the fluorescence excitation spectrum of this protoporphyrin-hemoglobin complex shifted, with increasing concentration, from 405 nm to 389 nm. A similar shift was observed when titrating a solution of free protoporphyrin with hemoglobin. The Soret maximum of free protoporphyrin itself, on the other hand, was not concentration-dependent. These observations indicate that spectrofluorometric measurements do not allow conclusions concerning the mode of protoporphyrin binding to hemoglobin. Experiments on protoporphyrin exchange between the hemoglobins A, F and S reinforced the previously drawn conclusion that protoporphyrin is bound to hemoglobin at the heme-binding sites.

Decreased haem synthetase activity in blood cells of patients with erythropoietic protoporphyria

A constant finding in erythropoietic protoporphyria (E.P.P.) is a raised protoporphyrin content of the erythrocytes. It has been shown before that the biosynthesis of this protoporphyrin takes place in the erythroid cell. In circulating blood cells of patients with E.P.P. the haem synthetase activity is significantly decreased. This observation and the increased protoporphyrin concentration in the cells can be explained by assuming a decreased stability of haem synthetase in the red blood cells of E.P.P. patients.