A novel pathway activated by somatostatin receptor type 2 (SST2): Inhibition of pituitary tumor cell migration and invasion through cytoskeleton protein recruitment.

The pharmacological therapy of GH-secreting pituitary tumors is based on somatostatin (SS) analogs that reduce GH secretion and cell proliferation by binding mainly SS receptors type 2 (SST2). Antimigratory effects of SS have been demonstrated in different cell models, but no data on pituitary tumors are available. Aims of our study were to evaluate SST2 effects on migration and invasion of human and rat tumoral somatotrophs, and to elucidate the molecular mechanism involved focusing on the role of cofilin and filamin A (FLNA). Our data revealed that SST2 agonist BIM23120 significantly reduced GH3 cells migration (-22% ± 3.6%, p < 0.001) and invasion on collagen IV (-31.3% ± 12.2%, p < 0.01), both these effects being reproduced by octreotide and pasireotide. Similar results were obtained in primary cultured cells from human GH-secreting tumors. These inhibitory actions were accompanied by a marked increase in RhoA/ROCK-dependent cofilin phosphorylation (about 2.7-fold in GH3 and 2.1-fold in human primary cells). Accordingly, the anti-invasive effect of the SS analog was mimicked by the overexpression in GH3 cells of the S3D phosphomimetic cofilin mutant, and abolished by both phosphodeficient S3A cofilin and a specific ROCK inhibitor that prevented cofilin phosphorylation. Moreover, FLNA silencing and FLNA dominant-negative mutants FLNA19-20 and FLNA21-24 transfection demonstrated that FLNA plays a scaffold function for SST2-mediated cofilin phosphorylation. Accordingly, cofilin recruitment to agonist-activated SST2 was completely lost in FLNA silenced cells. In conclusion, we demonstrated that SST2 inhibits rat and human tumoral somatotrophs migration and invasion through a molecular mechanism that involves FLNA-dependent cofilin recruitment and phosphorylation.

The cytoskeleton actin binding protein filamin A impairs both IGF2 mitogenic effects and the efficacy of IGF1R inhibitors in adrenocortical cancer cells.

Adrenocortical carcinomas (ACCs) overexpress insulin-like growth factor 2 (IGF2), that drives a proliferative autocrine loop by binding to IGF1R and IR, but IGF1R/IR-targeted therapies failed in ACC patients. The cytoskeleton actin-binding protein filamin A (FLNA) impairs IR signalling in melanoma cells. Aims of this study were to test FLNA involvement in regulating IGF1R and IR responsiveness to both IGF2 and inhibitors in ACC. In ACC cells H295R and SW13 and primary cultures (1ACC, 4 adenomas) we found that IGF1R and IR interacted with FLNA, and FLNA silencing increased IGF1R and reduced IR expression, with a downstream effect of increased cell proliferation and ERK phosphorylation. In addition, FLNA knockdown potentiated antiproliferative effects of IGF1R/IR inhibitor Linsitinib and IGF1R inhibitor NVP-ADW742 in H295R. Finally, Western blot showed lower FLNA expression in ACCs (n = 10) than in ACAs (n = 10) and an inverse correlation of FLNA/IGF1R ratio with ERK phosphorylation in ACCs only. In conclusion, we demonstrated that low FLNA levels enhance both IGF2 proliferative effects and IGF1R/IR inhibitors efficacy in ACC cells, suggesting FLNA as a new factor influencing tumor clinical behavior and the response to the therapy with IGF1R/IR-targeted drugs.

Octreotide and pasireotide effects on medullary thyroid carcinoma (MTC) cells growth, migration and invasion.

Medullary thyroid carcinoma (MTC) is a rare neuroendocrine neoplasm of the parafollicular thyroid C cells. Although somatostatin receptors are expressed by MTCs, treatment with octreotide has shown poor efficacy, whereas recently pasireotide has demonstrated antiproliferative effects in persistent postoperative MTCs. Aim of this study was to test the effects of octreotide and pasireotide on MTC cells proliferation, cell cycle proteins expression, MAPK activation, apoptosis, calcitonin secretion, migration and invasion in TT cell line as well as in primary MTC cultured cells. Our results showed that both octreotide and pasireotide reduced TT cell proliferation (-35.2 ± 12.1%, p < 0.001, and -25.3 ± 24.8%, p < 0.05, at 10-8 M, respectively), with concomitant inhibition of ERK phosphorylation and cyclin D1 expression. This cytostatic effect was accompanied by a proapoptotic action, with an increase of caspase3/7 activity of 1.5-fold. Moreover, both octreotide and pasireotide inhibited cell migration (-50.9 ± 11.3%, p < 0.01, and -40.5 ± 17%, p < 0.05, respectively) and invasion (-61.3 ± 35.1%, p < 0.05, and -49.7 ± 18%, p < 0.01, respectively). No effect was observed on calcitonin secretion. We then tried to extend these observations to primary cultures (n = 5). Octreotide and/or pasireotide were effective in reducing cells proliferation in 3 out of 5 tumors, and to induce cell apoptosis in 1 out of 3 MTCs. Both octreotide and pasireotide were able to reduce cell migration in all MTC tested. SST2, SST3 and SST5 were expressed in all MTC, with a tendency to increased expression of SST2 in RET mutated vs wild type MTCs. In agreement, inhibition of mutated RET in TT cells reduced SST2 expression. In conclusion, we demonstrated that octreotide and pasireotide inhibited cell proliferation and invasiveness in a subset of MTC, supporting their potential use in the control of tumor growth.

Cofilin is a mediator of RET-promoted medullary thyroid carcinoma cell migration, invasion and proliferation.

Medullary thyroid carcinoma (MTC) is a rare neuroendocrine tumor that originates from parafollicular thyroid C cells and accounts for 5% of thyroid cancers. In inherited cases of MTC, and in about 40% of sporadic cases, activating mutations of the receptor tyrosine kinase proto-oncogene RET are found. Constitutively active RET triggers signaling pathways involved in cell proliferation, survival and motility, but the mechanisms underlying malignant transformation of C-cells have been only partially elucidated. Cofilin is a key regulator of actin cytoskeleton dynamics. A crucial role of cofilin in tumor development, progression, invasion and metastasis has been demonstrated in different human cancers, but no data are available in MTC. Interestingly, RET activation upregulates cofilin gene expression. The aim of this study was to investigate cofilin contribution in invasiveness and growth of MTC cells, and its relevance in the context of mutant RET signaling. We found that cofilin transfection in human MTC cell line TT significantly increased migration (178 ±â€¯44%, p < 0.001), invasion (165 ±â€¯28%, p < 0.01) and proliferation (146 ±â€¯18%, p < 0.001), accompanied by an increase of ERK1/2 phosphorylation (2.23-fold) and cyclin D1 levels (1.43-fold). Accordingly, all these responses were significantly reduced after genetic silencing of cofilin (-55 ±â€¯10% migration, p < 0.001, -41 ±â€¯8% invasion, p < 0.001, -17 ±â€¯3% proliferation, p < 0.001). These results have been confirmed in primary cells cultures obtained from human MTCs. The inhibition of constitutively active RET in TT cells by both the RET pharmacological inhibitor RPI-1 and the transfection of dominant negative RET mutant (RETΔTK) resulted in a reduction of cofilin expression (-37 ±â€¯8%, p < 0.001 and -31 ±â€¯16%, p < 0.01, respectively). Furthermore, RPI-1 inhibitory effects on TT cell migration (-57 ±â€¯13%, p < 0.01), but not on cell proliferation, were completely abolished in cells transfected with cofilin. In conclusion, these data indicate that an unbalanced cofilin expression, induced by oncogenic RET, contributes to promote MTC invasiveness and growth, suggesting the possibility of targeting cofilin pathway for more effective treatment of MTC.

Cytoskeleton actin-binding proteins in clinical behavior of pituitary tumors.

Although generally benign, pituitary tumors are frequently locally invasive, with reduced success of neurosurgery and unresponsive to pharmacological treatment with somatostatin or dopamine analogues. The molecular basis of the different biological behavior of pituitary tumors are still poorly identified, but a body of work now suggests that the activity of specific cytoskeleton proteins is a key factor regulating both the invasiveness and drug resistance of these tumors. This review recapitulates the experimental evidence supporting a role for the actin-binding protein filamin A (FLNA) in the regulation of somatostatin and dopamine receptors expression and signaling in pituitary tumors, thus in determining the responsiveness to currently used drugs, somatostatin analogues and dopamine receptor type 2 agonists. Regarding the regulation of invasive behavior of pituitary tumoral cells, we bring evidence to the role of the actin-severing protein cofilin, whose activation status may be modulated by dopaminergic and somatostatinergic drugs, through FLNA involvement. Molecular mechanisms involved in the regulation of FLNA expression and function in pituitary tumors will also be discussed.

cAMP/PKA-induced filamin A (FLNA) phosphorylation inhibits SST2 signal transduction in GH-secreting pituitary tumor cells.

An efficient intracellular response to somatostatin analogs (SSA) in pituitary tumors requires filamin A (FLNA). Since cAMP pathway plays an important role in GH-secreting pituitary tumors pathogenesis and FLNA is phosphorylated by PKA on S2152, aim of this study was to investigate in tumoral somatotrophs the impact of cAMP pathway activation and SSA stimulation on FLNA phosphorylation and the consequences on SST2 function. We found a PKA-mediated increase (2-fold) and SST2 agonist-induced decrease (-50%) of FLNA phosphorylation in GH3, GH4C1 and primary somatotroph tumor cells. This modification regulates FLNA function. Indeed, phosphomimetic S2152D FLNA mutant, but not phosphodeficient S2152A, abolished the known SSA antitumoral effects, namely: 1) inhibition of cell proliferation, reduction of cyclin D3 and increase of p27; 2) increase of cell apoptosis; 3) inhibition of cell migration via RhoA activation and cofilin phosphorylation. Coimmunoprecipitation and immunofluorescence assays showed that S2152A FLNA was recruited to activated SST2, whereas S2152D FLNA constitutively bound SST2 on the plasma membrane, but prevented Gαi proteins recruitment to SST2. In conclusion, we demonstrated that FLNA phosphorylation, promoted by cAMP pathway activation and inhibited by SSA, prevented SST2 signaling in GH-secreting tumoral pituitary cells.

Integrin-dependent induction of functional urokinase receptors in primary T lymphocytes.

In order to reach the sites of inflammation, lymphocytes leave the bloodstream and migrate into peripheral tissues, in a process involving integrin-mediated adhesion to the vascular endothelium, followed by transmigration across the endothelial barrier and through the underlying interstitial matrix. We have investigated the role of the plasminogen activator/plasmin system in normal T cell migration. Receptors for urokinase plasminogen activator (uPAR) were not expressed in resting T lymphocytes, but could be efficiently induced at the mRNA and protein level by coclustering of the antigen receptor complex and beta1 or beta2 integrins, through a signalling pathway involving both protein kinase C activation and an increase in intracellular cyclic AMP. Catalytic activation of plasminogen by uPAR-expressing T cells promoted their migration through an extracellular matrix in vitro. Plasmin-induced invasion was inhibited by plasmin-and urokinase inhibitors and by anti-uPAR antibodies. Finally, cytofluorimetric and immunohistochemical analysis of primary human tumor specimens showed the presence of uPAR positive infiltrating T cells in vivo. Collectively, these findings suggest that plasminogen activation may play a role in lymphocyte migration in vivo, and that integrin-dependent expression of membrane-associated endopeptidases could represent an additional step in the regulated process of leukocyte transmigration.

Effects of octreotide treatment on the proliferation and apoptotic index of GH-secreting pituitary adenomas.

To investigate the effects of octreotide administration on the growth rate of GH-secreting pituitary adenomas, we measured both the Ki-67 labeling index (LI) and the apoptotic index in tumor specimens from octreotide-treated or matched untreated acromegalic patients. Thirty-nine patients who received octreotide until the day of or the day before surgery and 39 untreated patients matched for sex, age, tumor size, extension, and invasiveness were studied. Immunocytochemical analysis was performed on paraffin-embedded material using a monoclonal antibody (MIB-1) directed against a proliferation-associated nuclear antigen, Ki-67, to measure the growth fraction. Apoptosis was assessed by the terminal deoxynucleotidyl transferase-mediated deoxy-UTP nick endlabeling method, using a monoclonal antibody recognizing areas of DNA fragmentation. The Ki-67 LI and apoptosis were counted on separate slides in at least 1000 evaluable cells. Octreotide-treated patients showed a lower Ki-67 LI (1.8 +/- 0.3%) than untreated controls (3.8 +/- 0.7%; P < 0.02). Overall, the mean Ki-67 LI of treated patients was 53% lower than that in untreated patients. The antiproliferative effect of octreotide occurred independently of tumor extension and invasiveness. Octreotide-treated and untreated patients showed similar apoptotic indexes (0.6 +/- 0.2% and 0.8 +/- 0.3%, respectively). There was a positive correlation between the Ki-67 LI and the apoptotic index (r = 0.29; P < 0.03). Our study demonstrates that acromegalic patients receiving chronic octreotide treatment have a lower value of the proliferation marker Ki-67, but no significant difference in the apoptotic index compared with matched untreated patients. The antiproliferative effect of octreotide on GH-secreting adenomas should imply a lower risk of tumor growth during long-term chronic treatment with the drug.

In vivo evaluation of timing, degree, and distribution of bacterial translocation following experimental small bowel transplantation.

These studies were designed to evaluate the correlation between morphologic and functional changes after heterotopic auxiliary small bowel isograft with systemic venous drainage and two ostomies in 20 Lewis rats. Morphologic damage of the graft was scored by full-thickness biopsies before surgery and 1, 3, 5, and 7 days after transplant. Functional evaluation of the graft was done, at the same time points, by urinary excretion of lactulose and mannitol injected in the proximal ostomy. The intestinal permeability was also studied by injecting Escherichia coli labeled with indium-111 oxine in the proximal ostomy. Translocation of radiolabeled bacteria was quantitated in extraintestinal tissues by radionuclide counts and number of viable organisms and in vivo by scintigraphic imaging. One day after transplant, significant graft damage (score 17.2 +/- 4.2) was observed when compared with the pretransplant value (7.3 +/- 2.6). The degree of tissue injury was similar on days 3 (15.8 +/- 3.5) and 5 (16.1 +/- 3.9) after transplant and remained high on day 7 (11.8 +/- 2.8). The lactulose to mannitol ratio showed a significantly increased permeability on day 1 (17.5) versus pretransplant values (2.6), remained high on day 3 (8.6), and returned to normal values on day 5 (2.8). Translocation of bacteria to distant organs, as measured by both radionuclide counts and number of viable organisms, was strikingly enhanced on day 1 after transplantation, compared with control animals, but returned to the pretransplant value on day 3. A good qualitative and quantitative correlation was observed between radionuclide counts in the extraintestinal organs and in vivo images obtained by scintigraphic scanning. In conclusion, in this model, timing and degree of bacterial translocation do not seem to correlate well, with the exception of the acute post-transplantation phase, with morphologic and permeability changes of the graft. Evaluation of translocation by scintigraphic imaging appears a suitable approach to study in vivo the kinetics and distribution of this process.

Radioimmunoguided surgery using iodine-125-labeled biotinylated monoclonal antibodies and cold avidin.

UNLABELLED: One of the limitations of intraoperative tumor detection with radiolabeled monoclonal antibody (Mab), by means of a gamma-detecting probe (GDP), is the long time interval needed between Mab injection and surgery to obtain low blood-pool activity. Such an interval can be shortened considerably, exploiting the high affinity between avidin and biotin. METHODS: Twenty patients with colorectal cancer were injected with 1 mg of biotinylated 125I monoclonal antibodies followed, 48 hr later, by a chase of cold avidin. During surgery, the GDP was used to detect radioactive emissions from the tumor and normal tissue. Tumor tissue samples were analyzed in vitro by immunohistochemical tests for the presence of tumor antigens and in vivo antibody localization. RESULTS: At the time of surgery (average 7 days postinjection), the mean value of circulating radioactivity was 6% +/- 3% of the injected dose. Of 20 patients studied, tumors were localized in 13 cases (65%). Subclinical tumors were detected in 3 patients (15%). CONCLUSION: The use of 125I-labeled biotinylated Mabs followed by avidin as a chase enhances the applicability and effectiveness of radioimmunoguided surgery technology and will allow the use of radioisotopes with a shorter half-life than 125I.

Computed cell cycle and DNA histogram analyses in image cytometry in breast cancer.

AIMS: To analyse the cell cycle and DNA histogram components in data from DNA static cytometry and, in particular, to investigate the influence of the length of time the slides are exposed to the light of the cytophotometer in evaluating the G0/G1 peak. METHODS: DNA static cytometry was performed on 18 Feulgen stained imprints and six histological sections taken from six breast carcinomas. The total optical density values obtained were analysed using software commercially available as Multicycle. DNA flow cytometry was performed on the same cases. RESULTS: The proportions of nuclei related to the cell cycle components from DNA static cytometric data, obtained from Feulgen stained cytological smears, were almost identical with those obtained from DNA flow cytometric data. Moreover, additional information was obtained from the DNA static cytometry frequency histogram and the proportions of nuclei below the diploid G0/G1 peak and above the G2 phase. Discrepancies between DNA static cytometry and DNA flow cytometry were seen in the large coefficients of variation of the G0/G1 peaks obtained with the former method of analysis, even though a better correspondence was found when the exposure time of the slides to the light of the cytophometer was conspicuously shortened. The information obtained from histological sections seemed to be similar to that obtained from DNA flow cytometry when a single cell population was present; a single cell population was detected in two out of the three cases in which two distinct populations had been present in DNA flow cytometry. CONCLUSIONS: The computer analysis of DNA static cytometric data obtained from Feulgen stained cytological specimens provides the type of information on the cell cycle which is usually obtainable only from DNA flow cytometry. Correspondence with the DNA data from histological sections, however, was poor.

Proliferation index of nonfunctioning pituitary adenomas: correlations with clinical characteristics and long-term follow-up results.

OBJECTIVE: The recurrence of nonfunctioning pituitary adenomas (NFPAs) after surgical removal is common. The aim of our study was to investigate and correlate the growth fraction of NFPAs with clinical characteristics and long-term follow-up results. METHODS: Tumor specimens were obtained from 101 consecutive patients with NFPAs (48 female patients and 53 male patients; mean age, 52.0 +/- 1.5 yr). Specimens were immediately fixed in 10% buffered formalin and then embedded in paraffin. The Ki-67 antigen was assessed by immunocytochemical analysis using the monoclonal antibody MIB-1. The Ki-67 antigen labeling index (LI) was determined by counting a total of at least 1,000 neoplastic nuclei. RESULTS: The mean Ki-67 LI for the 101 patients was 2.4 +/- 0.3% (range, 0-23.0%). Only age at surgery was inversely correlated with the Ki-67 LI; sex, maximal tumor diameter, and invasiveness into the cavernous sinuses did not significantly affect the Ki-67 LI. The mean follow-up period was 39.7 +/- 2.1 months. During follow-up monitoring, 23 patients experienced tumor recurrence, after a mean period of 28.6 +/- 4.8 months. Invasiveness of the tumor on preoperative magnetic resonance imaging scans was the strongest predictor of late tumor recurrence, followed by previous pituitary surgery, younger age, and lack of postoperative radiotherapy. The Ki-67 LI had no independent prognostic value. CONCLUSION: Our study suggests that the clinical characteristics of patients with NFPAs, except for age at surgery, are not correlated with the Ki-67 LI. Moreover, the Ki-67 LI does not seem to provide independent information to identify patients at high risk for tumor recurrence.

Adjuvant role of MIB1 index in differentiating serous ovarian tumors-preliminary report.

Atypically proliferating serous tumors (APST) account for 15% of all ovarian serous epithelial neoplasms. The differences between benign, borderline and malignant ovarian tumors is principally due to their cellular proliferative potential. By means of MIB1 expression we could recognize differences in proliferation among serous ovarian tumors, overcoming interobserver variability. Thirty-three patients with serous ovarian tumors, treated at S. Raffaele Hospital, University of Milan between November 1, 1992 and July 31, 1994 were used as study the population: 9 patients had serous cystoadenocarcinoma, 14 patients had APST and 10 patients had serous cystoadenoma. Pathological slides of all the cases were reviewed and immunohistochemical analysis was performed on formalin fixed, paraffin was embedded tissue. Pearson's Chi-square test and Fisher's exact test were performed for statistical evaluation. The percentage of MIB1 positive neoplastic cells ranged from, 0% to 2.1% (median 0.45%; mean 0.69%) in cystoadenomas, 1.3% to 7% (median 2.9%; mean 3.98%) in APSTs and 4.7% to 20.3% (median 6.95%; mean 9.51%) in cystoadenocarcinomas (p < 0.0001; F = 47.7). A High percentage expression of MIB1 in a serous tumor, initially diagnosed as APST, promoted a wider sampling of the surgical specimen confirming the presence of a carcinomatous component. MIB1 index is reported as representative of cellular proliferative potential. The analysis of MIB1 index provided valuable information in addition to that gained by conventional microscopic study in all cases where diagnostic difficulties arose in assessing APST.

Coexpression of insulin and somatostatin in single secretory granules of a pancreatic endocrine tumor.

Pancreatic endocrine tumors, examined by immunohistochemistry, were found to be associated with multihormonal production, and recent studies, performed by employing double immunostaining methods, reported the coexpression of hormones in single cells or in single secretory granules. These findings have been attributed to the heterogeneity of the neoplastic cell population, characterized by the emergence of clones with different phenotypes, and were considered a sign of cell dedifferentiation or malignancy. In this study we describe a case of pancreatic endocrine tumor that showed focal colocalization of insulin and somatostatin in single secretory granules, by means of double labelling immunoelectron microscopy. We think that this observation can be linked to the hypothesis of those authors who speculated upon the appearance of polycrine cells in human fetal pancreas during embryogenesis.

Morphometric evaluation of fine needle biopsy of single thyroid nodules.

Area, perimeter, maximum diameter and form factors of nuclei of FNABs of thyroid nodules were measured with a MOP Videoplan. 23 cases were selected from patients with a scintigraphically cold single thyroid nodule. The mean values of area, perimeter and maximum diameter were significantly different (p less than 0.001) between the adenoma and carcinoma cases; no differences were found for the form factors. Although the analyses gave significant results, a certain amount of overlap of the benign and malignant populations was present; therefore the significance of the standard deviation, assumed to be an index of variability of the nuclear area, was evaluated and this parameter was found to discriminate the two populations. The standard deviation of the nuclear area measured in 14 cases diagnosed as suspicious gave 77% accuracy in discriminating benign from malignant cases.

Flow cytometric diagnosis of partial mole.

To differentiate histologically partial hydatidiform moles (PM) and complete hydatidiform moles (CM) may be difficult. Cytogenetic studies have shown that PMs often had a triploid karyotype while CMs were always diploid. We assessed the DNA content of 31 paraffin-embedded cases of trophoblastic disease with flow cytometry. Twenty-four cases were histologically diagnosed as PM, 3 cases as CM; the others as hydropic abortion (2 cases), choriocarcinoma (1 case), and persistent trophoblastic disease (1 case). Four normal term placentas were used as diploidy controls. In 9 cases the results of the cytogenetic analysis were available. All placental specimens included also maternal tissue as an internal control. Eight of the 24 histologically diagnosed PMs were triploid; there was agreement in 8 cases out of 9 (90%) between the flow cytometric analysis and the karyotypic determination of ploidy. All normal controls as well as the hydropic abortion, the CM and the persistent trophoblastic disease were diploid. Abnormal content of DNA (DI = 1.3) was observed in the choriocarcinoma. Our results show that flow cytometric analysis of DNA content is a reliable and fast method of diagnosing PM on paraffin-embedded material.

Role of DNA ploidy and ERB-B2 oncogene expression in the prognosis of endometrial carcinoma.

Seventy-three patients with endometrial carcinoma have been retrospectively evaluated in this paper. Stage, grade, depth of myometrial invasion, flow cytometric DNA ploidy and ERB-B2 oncogene expression by immunohistochemical method have been analyzed on paraffin embedded tissue. Results showed the existence of a significant correlation between stage and grade of neoplasia and between DNA ploidy and course of disease; it has been observed that patients with aneuploid tumor tend to have a shorter time before relapse of disease. No significant correlation between depth of myometrial invasion and survival was found. Besides, it has been shown that tumours with ERB-B2 oncogene hyperexpression seem to have a more aggressive evolution.

Heterogeneity and susceptibility to apoptosis of human renal carcinoma cells in vitro.

Tumors are heterogeneous in terms of morphology and susceptibility to drugs or radiation. Among primary and metastatic cells of a human renal carcinoma, a population (type II) of larger cells with prominent nucleoli, eosinophilic globules of intermediate filaments in paranuclear bundles, margination of subcellular organelles and peripheral pools of glycogen was evident. Paranuclear structures were recognized by monoclonal antibodies specific for cytokeratin 8, 18 and 19, but not by vimentin specific antibodies. We propagated a cell line in vitro (referred to as BKR cells), and observed culture in vitro, the almost complete disappearance of the type II cells. Pharmacological agents that influence cell differentiation, such as retinoic acid, rescued the expression of type II cells in vitro. Long-term treatments with insulin or alpha-interferon, but not with the epithelial growth factor (EGF), similarly differentiated BKR cells and abated their susceptibility to spontaneous and actinomycin-D induced apoptosis. These data support the contention that differentiation of tumor cells is actively maintained in vivo and further strengthen the caveat on tumor lines stabilized in vitro, that poorly represent the morphologic and antigenic heterogeneity of neoplasms in vivo.

Localization of biotinylated monoclonal antibodies (B72.3 and F023C5) in patients with colorectal cancer.

The recognition and treatment of neoplastic lesions in early phases are among the most important aims of research using monoclonal antibodies (MoAb). Recent studies have demonstrated that the use of radiolabelled MoAb directed against tumor associated antigens and hand-held gamma detecting probe (GDP) could help in the recognition of primary tumors and metastases. The goal of this study was to investigate the in vivo antibody reaction as shown by histologic preparations after injection of 125I biotinylated MoAb (B72.3 or F023C5) before surgery and to compare the immunohistochemical results with those obtained with GDP in colorectal cancer. We studied 15 cases of patients with primary or recurrent colorectal cancer. The biotinylated, radiolabelled antibody administered in vivo could be seen in frozen sections with streptoavidin peroxidase complex. In 14 cases there was agreement between GDP observations and detection of the in vivo injected biotinylated MoAb with direct staining using streptoavidin peroxidase conjugate. The use of MoAbs thus provides a means of correlating the intraoperative signal with the presence of the injected antibodies on the tumor.

Cell loss and proliferation in non-small cell lung carcinoma: correlation with histological subtype.

BACKGROUND: Cell kinetic data are important indicators of the aggressiveness of tumor and treatment response. The size of a neoplasm depends on the balance between cell proliferation and death. Thus, the analysis of the kinetics of cell proliferation and death may explain differences in the rates of tumour progression. METHODS: We studied apoptosis and proliferative indices in 95 cases of non-small cell lung carcinomas. The analysis was performed on paraffin-embedded tissue, by both MIB-1 immunocytochemical detection to establish the proliferation index and the in-situ end labelling method for the apoptosis index. The two indices were related. RESULTS: Our results showed a high proliferative index and cell loss rate in squamous cell carcinoma, and a low proliferative index and cell loss rate in adenocarcinoma, suggesting two different growth patterns. CONCLUSION: These findings could explain the different biological behaviour and treatment response of the tumours. The tendency of a cancer cell to undergo apoptosis may be especially important for the chemotherapy of malignant tumours with a low growth rate, which are typically resistant to cytostatic agents.