Automatic lung segmentation in COVID-19 patients: Impact on quantitative computed tomography analysis

Purpose

To assess the impact of lung segmentation accuracy in an automatic pipeline for quantitative analysis of CT images.

Methods

Four different platforms for automatic lung segmentation based on convolutional neural network (CNN), region-growing technique and atlas-based algorithm were considered. The platforms were tested using CT images of 55 COVID-19 patients with severe lung impairment. Four radiologists assessed the segmentations using a 5-point qualitative score (QS). For each CT series, a manually revised reference segmentation (RS) was obtained. Histogram-based quantitative metrics (QM) were calculated from CT histogram using lung segmentationsfrom all platforms and RS. Dice index (DI) and differences of QMs (ΔQMs) were calculated between RS and other segmentations.

Results

Highest QS and lower ΔQMs values were associated to the CNN algorithm. However, only 45% CNN segmentations were judged to need no or only minimal corrections, and in only 17 cases (31%), automatic segmentations provided RS without manual corrections. Median values of the DI for the four algorithms ranged from 0.993 to 0.904. Significant differences for all QMs calculated between automatic segmentations and RS were found both when data were pooled together and stratified according to QS, indicating a relationship between qualitative and quantitative measurements. The most unstable QM was the histogram 90th percentile, with median ΔQMs values ranging from 10HU and 158HU between different algorithms.

Conclusions

None of tested algorithms provided fully reliable segmentation. Segmentation accuracy impacts differently on different quantitative metrics, and each of them should be individually evaluated according to the purpose of subsequent analyses.

Androgen-responsive and -unresponsive prostate cancer cell lines respond differently to stimuli inducing neuroendocrine differentiation

The treatment of advanced prostate cancer (CaP) with androgen deprivation therapy inevitably renders the tumours castration resistant and incurable. Under these conditions, neuroendocrine differentiation (NED) of CaP cells occurs and neuropeptides released by neuroendocrine cells facilitate tumour progression. Pharmacological strategies aiming to prevent or delay NED during androgen ablation could, therefore, increase the effectiveness of the therapy. Mechanisms and pathways inducing NED in CaP are poorly understood and data are often discordant. In the present study, we used several CaP cell lines (androgen-responsive: LNCaP, PC3-AR, 22RV1 and -irresponsive: DU145 and PC3) to evaluate NED after androgen deprivation or treatment with epidermal growth factor (EGF). NED was determined by neuron-specific enolase and chromogranin A expression and by the occurrence of morphological changes in the cells. Androgen-deprivation conditions induced NED in LNCaP and PC3-AR, but not in 22Rv1, PC3 and DU145 cells. LNCaP and PC3-AR cells also became resistant to thapsigargin-induced apoptosis. In all the AR-positive cell lines, androgen deprivation caused a decrease in androgen receptor expression indicating that it is downregulated irrespective of NED induction. Treatment with EGF induced NED in DU145 cells and the EGF receptor inhibitor gefinitib prevented the process. On the contrary, no effect of EGF was demonstrated in LNCaP or 22Rv1 cells. CaP cell lines did not respond univocally to treatments inducing NED, suggesting that studies on this topic should be performed in a wide spectrum of cell models which can be more indicative of the tumour variability in vivo.

In vivo effects of rosiglitazone in a human neuroblastoma xenograft

BACKGROUND

Neuroblastoma (NB) is the most common extra-cranial solid tumour in infants. Unfortunately, most children present with advanced disease and have a poor prognosis. There is in vitro evidence that the peroxisome proliferator-activated receptor gamma (PPARgamma) might be a target for pharmacological intervention in NB. We have previously demonstrated that the PPARgamma agonist rosiglitazone (RGZ) exerts strong anti-tumoural effects in the human NB cell line, SK-N-AS. The aim of this study was to evaluate whether RGZ maintains its anti-tumoural effects against SK-N-AS NB cells in vivo.

METHODS AND RESULTS

For this purpose, tumour cells were subcutaneously implanted in nude mice, and RGZ (150 mg kg(-1)) was administered by gavage daily for 4 weeks. At the end of treatment, a significant tumour weight inhibition (70%) was observed in RGZ-treated mice compared with control mice. The inhibition of tumour growth was supported by a strong anti-angiogenic activity, as assessed by CD-31 immunostaining in tumour samples. The number of apoptotic cells, as determined by cleaved caspase-3 immunostaining, seemed lower in RGZ-treated animals at the end of the treatment period than in control mice, likely because of the large tumour size observed in the latter group.

CONCLUSIONS

To our knowledge, this is the first demonstration that RGZ effectively inhibits tumour growth in a human NB xenograft and our results suggest that PPARgamma agonists may have a role in anti-tumoural strategies against NB.

The critical role of SDF-1/CXCR4 axis in cancer and cancer stem cells metastasis

Chemokines exert their multifunctional role in several physiologic and pathologic processes through interaction with their specific receptors. Much evidence have revealed that metastatic spread tumor cells may use chemokine-mediated mechanisms. In particular, an involvement of stromal cell-derived factor-1 (SDF-1) in growth of primary tumors and in metastatic process has been demonstrated. Indeed, it has been suggested that CXCR4 expression by tumor cells, plays a critical role in cell metastasis by a chemotactic gradient to organs expressing the ligand SDF-1. Moreover, CXCR4 overexpression correlated with poor prognosis in many types of cancer. In physiologic condition, SDF-1 also plays an essential role modulating stem cell proliferation, survival, and homing through its canonical receptor CXCR4. Recently, several studies have demonstrated the existence of a small subset of cancer cells which share many characteristics with stem cells and named cancer stem cells (CSC). They constitute a reservoir of self-sustaining cells with the ability to maintain the tumor growth. In particular, most of them express CXCR4 receptor and respond to a chemotactic gradient of its specific ligand SDF-1, suggesting that CSC probably represent a subpopulation capable of initiating metastasis. This review focuses on the role of SDF-1/CXCR4 axis in cancer and in the metastatic progression by tumoral cells, as well as the role of CSC in tumor pathogenesis and in metastatic process. A better understanding of migratory mechanism involving cancer cells and CSC provides a powerful tool for developing novel therapies reducing both local and distant recurrences.

Elocalcitol inhibits inflammatory responses in human thyroid cells and T cells

T-helper 1 (Th1) cell-mediated inflammatory responses predominate in the early pathogenesis of Graves' disease (GD), whereas Th2 cell-mediated immunity may play a role in later stages. The chemokine CXCL10 and its receptor CXCR3 are expressed in most thyroid glands of early GD patients. Circulating CXCL10 levels inversely correlate with disease duration; CXCL10 maximal expression also correlates with interferon (IFN)gamma levels in recent GD onset. Methimazole (MMI) reduces CXCL10 secretion by isolated thyrocytes, decreases serum CXCL10 levels, and promotes a transition from Th1 to Th2 dominance in patients in GD active phase. Vitamin D receptor agonists exhibit antiinflammatory properties and promote tolerance induction. We investigated the effects and the mechanism of action of a nonhypercalcemic vitamin D receptor agonist, elocalcitol (BXL-628), compared with MMI on CXCL10 secretion induced by proinflammatory cytokines. Furthermore, we studied the effects of both drugs on Th1, Th17, and Th2 cytokine secretion in CD4+ T cells. ELISA, cytometry, immunocytochemistry, Western blot, and quantitative real-time PCR were used for protein and gene analysis. In human thyrocytes, elocalcitol inhibited IFNgamma and TNFalpha-induced CXCL10 protein secretion more potently than MMI. Elocalcitol impaired both cytokine intracellular pathways, whereas MMI was effective only on the IFNgamma pathway. In CD4+ T cells, elocalcitol decreased Th1- and Th17-type cytokines, and promoted Th2-type cytokine secretion. Elocalcitol and MMI inhibited Th1 cytokine-mediated responses in thyrocytes and CD4+ T cells. In addition, elocalcitol promoted a shift toward a Th2 response. In conclusion, elocalcitol could represent a novel pharmacological tool in the treatment of autoimmune thyroid diseases.

Methimazole inhibits CXC chemokine ligand 10 secretion in human thyrocytes

CXC chemokine ligand 10 (CXCL10) plays a pivotal role in the self-perpetuation of the inflammatory processes in patients with autoimmune thyroid disease. Treatment with methimazole (MMI) reduces serum CXCL10 in patients with Graves' disease. In isolated human thyrocytes, tumor necrosis factor (TNF)alpha demonstrates a potent synergistic effect on interferon (IFN)gamma-induced CXCL10 secretion. We investigated the mechanism underlying the synergism between IFNgamma and TNFalpha and the effect of MMI on CXCL10 secretion in human thyrocytes. A peroxisome proliferator-activated receptor gamma agonist, rosiglitazone (RGZ), a known inhibitor of T helper 1 (Th1)-mediated responses, was also studied for comparison. Experiments were carried out in human thyrocytes isolated from internodular parenchyma of thyroid tissues derived from patients who had undergone surgery for multinodular goiter. ELISA was used to measure CXCL10 levels in culture supernatant. Flow cytometry was used to assess IFNgamma membrane receptor expression. Specific mRNA analysis was performed by Taqman real-time PCR. Immunofluorescence was performed to detect nuclear translocation of nuclear factor-kappaB (NF-kappaB). In human thyrocytes, the synergistic effect of TNFalpha with IFNgamma on CXCL10 secretion is due to the upregulation of IFNgamma receptor expression. MMI decreased cytokine-induced CXCL10 secretion by reducing TNFalpha-induced upregulation of the IFNgamma receptor. RGZ decreased the cytokine-induced CXCL10 secretion by impairing NF-kappaB translocation, without affecting IFNgamma receptor. MMI and RGZ targeted thyrocytes with the same pharmacological potency, likely acting throughout different mechanisms. Targeting T helper 1-mediated autoimmune thyroid disease with drugs that impair different intracellular pathways could be a novel pharmacological tool.

Analysis of somatostatin receptors 2 and 5 polymorphisms in patients with acromegaly

OBJECTIVE

The aim of the study was to investigate the possible correlation of single nucleotide polymorphisms in somatostatin receptor (SSTR)2 and SSTR5 genes with the responsiveness to somatostatin analogs in a cohort of acromegalic patients.

STUDY DESIGN

Three single nucleotide polymorphisms (a-83 g, c-57 g, and t80c) of SSTR2 and three (t-461c, c325t, and c1004t) of SSTR5 were analyzed in 66 acromegalic patients with different responsiveness to somatostatin analogs and 66 healthy controls.

RESULTS

Allele frequencies in patients and controls were similar. No association between SSTR2 genotypes and GH and IGF-I levels was found. When considering SSTR5 variants, patients homozygous or heterozygous for the substitution c1004 (P+) showed basal IGF-I levels significantly lower than patients homozygous for 1004t (P-). Moreover, serum GH levels were lower in patients with P+/T- haplotype (having c1004 allele and no t-461 allele) than in those with P-/T+. No correlation between SSTR2 and SSTR5 genotypes, responsiveness to somatostatin therapy, and mRNA expression in the removed adenomas (n = 10) was found.

CONCLUSIONS

These data suggest a role for SSTR5 t-461c and c1004t alleles in influencing GH and IGF-I levels in patients with acromegaly, whereas SSTR2 and SSTR5 variants seem to have a minor role in determining the responsiveness to somatostatin analogs.

Loss of heterozygosity at the SS receptor type 5 locus in human GH- and TSH-secreting pituitary adenomas

SS receptor types 2 and 5 (sst2 and sst5) are involved in the control of secretion and proliferation of normal and tumoral somatotrophs and thyrotrophs. The mechanisms leading to reduced responsiveness to SS analogues in patients with pituitary tumors are poorly understood. The aim of the study was to verify the possible loss of heterozygosity (LOH) at the sst5 gene locus in somatotroph and thyrotroph adenomas by screening leukocyte and tumor DNA for two single nucleotide polymorphisms, i.e. C1004T leading to P335L change and T-461C in the 5'-upstream region. Among the 13 informative samples, 1 GH- and 1 TSH-secreting adenoma showed LOH at sst5 gene locus with the retention of Leu335 variant. By analyzing other polymorphic markers spanning from telomere to 16p13.3-13.2 boundaries, DNA deletion of at least 1 megabase was found in both tumors. LOH in thyrotroph adenoma was associated with unusual tumor aggressiveness that required a second surgery and resistance to SS analogs, while no obvious phenotype was identified in the case of the somatotroph adenoma. In conclusions, LOH at the sst5 gene locus is a rare phenomenon, occurring in about 10% of pituitary tumors, that seems to be associated with an aggressive phenotype, at least in thyrotroph adenomas. Further studies are required to confirm this association and to identify the genes, in addition to sst5, lost in these tumors.

Measurement of somatostatin receptor subtype 2 mRNA in breast cancer and corresponding normal tissue

Somatostatin analogs are effective in inhibiting growth of human breast cancer cell lines. These antiproliferative effects are mediated by specific receptors located on cell membranes. The somatostatin receptor subtype 2 (sst2) is the principal mediator of somatostatin effects in normal and cancer cells, and its presence has already been demonstrated in breast cancer. The purpose of our study was to evaluate the clinical relevance of the expression of sst2 by quantifying its mRNA in a large group of infiltrating breast cancers and their corresponding normal tissues. The expression of sst2 mRNA was measured with quantitative real time RT-PCR in 169 breast cancers and in their corresponding unaffected tissues. We evaluated the association of sst2 expression with the commonest clinical-pathologic features of breast cancer. The correlation with a marker of cell proliferation (Ki-67) and with receptor concentration was also evaluated. In cancer tissues, we found that the absolute concentrations of sst2 mRNA were significantly higher in estrogen receptor (ER)-positive samples (P=0.002) as well as in lymph-node-negative cancers (P=0.04) (Student's t-test or one-way ANOVA). In addition, sst2 mRNA was significantly higher in breast cancers than in corresponding unaffected tissues (P=0.0002). However, when the clinical-pathologic parameters were considered, this gradient maintained its statistical significance only in tumors expressing positive prognostic markers, such as the presence of ER (P=0.0005) and progesterone receptors (PgR) (P=0005), and the lack of lymph-node involvement (P=0.0003). The same difference was also significant in postmenopausal women (P=0.001) and in T1 patients (P=0.001). In addition, sst2 mRNA expression was significantly higher (P=0.008) in low-proliferating breast cancers. Finally, we found that the quantitative expression of sst2 mRNA was directly related to the PgR concentration in breast cancer tissues (P<0.001). Our data seem to indicate that an upregulation of sst2 gene expression is a common feature of breast cancers which, on the basis of conventional predictive parameters, are expected to have a better prognosis. Featuring a possible role of somatostatin analogs in combined endocrine therapies for breast cancer, our results seem to confirm that the sst2 status of the tumor should be previously investigated.

Inhibition of prostate cell growth by BXL-628, a calcitriol analogue selected for a phase II clinical trial in patients with benign prostate hyperplasia

OBJECTIVE

Calcitriol analogues might represent an interesting new therapy for benign prostate hyperplasia (BPH). We here report the preclinical characterization of BXL-628, an analogue selected for an ongoing double-blind, randomized, placebo-controlled phase II trial in BPH.

DESIGN

Experiments with BXL-628 were carried out in human BPH cells and in the ventral prostate of intact and castrated rats.

METHODS

BPH cell and rat prostate growth were evaluated along with morphological and biochemical hallmarks of apoptosis.

RESULTS

BXL-628 inhibited human BPH cell proliferation and induced apoptosis even in the presence of androgens or growth factors. It also decreased prostate growth to an extent similar to finasteride, inducing DNA fragmentation and apoptosis, both in intact and in testosterone-supplemented castrated rats. Accordingly, BXL-628, like finasteride, increased the expression of clusterin, a prostatic atrophy marker. However, BXL-628 did not inhibit 5 alpha-reductase 1 and 2, did not bind to the androgen receptor (AR) in BPH homogenates and did not affect AR-coupled luciferase activity. In addition, BXL-628 did not affect rat pituitary and testis activity or calcemia.

CONCLUSIONS

BXL-628 inhibited in vitro and in vivo prostate cell proliferation, and therefore might represent a novel, interesting option for the treatment of BPH.

Variable expression of the transcription factors cAMP response element-binding protein and inducible cAMP early repressor in the normal adrenal cortex and in adrenocortical adenomas and carcinomas

The molecular mechanisms leading to adrenocortical tumorigenesis have been only partially elucidated so far. Because the pituitary hormone ACTH, via activation of the cAMP pathway, regulates both cell proliferation/differentiation and steroid synthesis in the adrenal cortex, in this study we focused on the cAMP-dependent transcription factors cAMP responsive element modulator (CREM) and cAMP responsive element binding protein (CREB). We studied CREM and CREB expression by RT-PCR in human normal adrenal cortex (n = 3), adrenocortical adenomas (n = 8), and carcinomas (n = 8). We found transcripts corresponding to the isoforms alpha, beta, gamma, and tau2 of the CREM gene in all of the normal adrenal tissues, in the adenomas, and in seven of eight carcinomas. On the other hand, mRNA for the inducible cAMP early repressor isoforms, which derive from an internal promoter of CREM gene, was detected in the normal adrenal and in seven of eight adenomas, but in only three of eight carcinomas. Similarly, CREB transcripts were readily detectable in all normal adrenals and adenomas, whereas they were not found in four of eight adrenal carcinomas. To further characterize the carcinomas, telomerase activity and the expression of the ACTH receptor gene were determined. Telomerase activity in the carcinomas resulted in levels significantly higher than in the adenomas, whereas the levels of ACTH receptor mRNA were lower in the carcinomas. No correlation was found in the carcinomas between the levels of the ACTH receptor transcript and the loss of expression of CREB/inducible cAMP early repressor, suggesting that this alteration is not secondary to an upstream disregulation at the receptor level. In conclusion, our results suggest that an alteration in cAMP signaling may be associated with malignancies of the adrenal cortex.

[Somatostatin receptors in non-endocrine tumours]

The study of the antiproliferative action of somatostatin (ss) is important not only to understand the regulation of neuroendocrine tumours that express receptors (sst), but also non-endocrine tumours which express these receptors. We previously demonstrated the presence of sst2 in a wide panel of cell lines from human neuroblastoma. Although hypotheses have been put forward that treatment with ss or its analogs may be beneficial in oncological patients, this does not appear to be the case in neuroblastoma; patients with high sst2 levels (who are therefore sensitive to ss treatment) have per se a relatively positive outcome. Therefore, adjuvant treatment with ss is not necessary. Viceversa, patients with a poor prognosis are essentially characterized by a low expression of sst2 (and therefore are insensitive to a therapy with ss). In these patients adjuvant treatment with ss might be indicated, but would have little chance of success. Although the majority of neuroendocrine tumours expresses sst2, pancreas and prostate cancer express sst1 but not sst2, and are therefore insensitive to octreotide treatment which binds preferentially to sst2. Tumours like colorectal carcinoma and breast cancer also express sst2 in their more favourable forms. However, the concentration of sst2 in colorectal cancer is similar, if not lower than that in the surrounding normal tissue. Therefore, the probability of successful adjuvant therapy with ss is relatively low. In breast cancer, it is possible that sensitivity to estrogens may have a positive influence on the expression of sst2. This might justify clinical trials with ss in breast cancer.

Telomerase in endocrine and endocrine-dependent tumors

Telomerase, the ribonucleoprotein enzyme that elongates chromosomal ends, or telomeres, is repressed in most normal somatic cells but reactivated in transformed cells to compensate for the progressive erosion of the telomeres during cell divisions. In accordance with this hypothesis, the presence of telomerase activity has been reported in more than 90% of human cancers, whereas most normal tissues or benign tumors contain low or undetectable telomerase activity. Reactivation of telomerase has also been widely reported in endocrine neoplasms and in hormone-related cancers. In the present study, we review the most recent publications on telomerase in these types of tumors. The hormonal regulation of telomerase activity and the possible strategies for cancer therapy based on the inhibition of telomerase has also been discussed.

Telomerase in urological malignancy

PURPOSE

Telomerase is a ribonucleoprotein enzyme that compensates for the progressive erosion of chromosomal ends, called telomeres. In most somatic cells telomerase expression is repressed and telomeres progressively shorten after each cell division, causing cell senescence. Conversely telomerase is active in most human cancers, maintaining the integrity of chromosome ends and representing an important step in cell immortalization and carcinogenesis. The large and increasing interest in telomerase was motivated by the demonstration that more than 90% of human cancers are telomerase positive, whereas most normal tissues or benign tumors contained low or undetectable telomerase activity. We addressed the most recent data on telomerase detection in urological malignancy. Approaches to telomerase inhibition as a future anti-cancer therapy are also discussed.

MATERIALS AND METHODS

We comprehensively reviewed the most recent and significant publications in this field using current issues of specific journals and a MEDLINE search.

RESULTS

Telomerase is often expressed in bladder (90%), prostate (80%) and renal (69%) carcinoma. A variable but significant percent of normal tissues from tumor adjacent zones or noncancer samples are positive for telomerase. The clinical role of telomerase is still questionable in renal cancer, while important insights into the diagnostic role of telomerase in bladder and prostate carcinoma are increasing. Telomerase detection in exfoliated cells collected with urine or bladder washings seems a promising tool for the diagnosis and management of bladder cancer.

CONCLUSIONS

Larger perspective studies of larger groups of patients are required to discover an appropriate role for telomerase when assessing these tumors. The improvement of quantitative methods to evaluate the expression of telomerase is a cornerstone in the complete clarification of the clinical relevance of telomerase.

Real-Time quantitative reverse transcriptase-polymerase chain reaction (RT-PCR) for the measurement of prostate-specific antigen mRNA in the peripheral blood of patients with prostate carcinoma using the taqman detection system

Circulating prostate cells can be detected in peripheral blood of patients with clinically localized or advanced prostate carcinoma. Traditionally, nested reverse transcriptase-polymerase chain reaction (RT-PCR) is used for this as a sensitive, but qualitative only, detection system. We developed a quantitative real-time RT-PCR method for measuring prostate-specific antigen (PSA) mRNA in peripheral blood of prostate cancer patients. A quantitative assay was developed using an external standard reference curve generated with RNA from the human prostate cell line LNCaP. Basal blood samples were collected from 44 patients without evidence of distant metastases and from 30 healthy controls. In 29 patients surgically treated with radical prostatectomy, the measurement of PSA mRNA was performed in blood samples collected before, at the end and 6 days after surgery. In 14 patients treated with radiotherapy, the measurements were repeated at 3-month intervals to evaluate time-related changes during therapy. The measurements were also performed for one year at 3-month intervals in one patient treated with anti-androgen therapy. We found detectable PSA mRNA in 14/44 (32%) basal blood samples. A wide range of values were observed in these patients, ranging from 0.5 to 1724 pg of total LNCaP RNA/ml blood. In patients undergoing radical prostatectomy, circulating PSA mRNA was detectable in eight patients in basal samples, and in seven of them also in blood specimens collected at the end of surgery, showing an increase in only two patients. In blood samples collected 6 days later, PSA mRNA was dramatically reduced in all patients, but still present in seven of them. In four patients, whose basal samples were negative, PSA mRNA was detectable in samples collected at the end of surgery and three of them were negative after 6 days. In patients who did not receive surgical treatment, a rapid decrease in PSA mRNA was demonstrated in five patients treated with radiotherapy and in one patient undergoing androgen deprivation. No detectable PSA mRNA was found in healthy controls. The levels of PSA mRNA in peripheral blood from patients with prostate carcinoma can be easily measured by this sensitive, quantitative and reliable procedure. This assay is a promising tool for the detection and follow-up of these patients.

Evidence for elevated telomerase activity in small cell carcinoma of the bladder

Telomerase activity was found to be elevated using a quantitative assay on snap-frozen protein extracts of exfoliated cells in urine and bladder washings and tumor tissue obtained from a male patient with small cell carcinoma of the bladder. To the best of our knowledge, this is the first demonstration of elevated values of telomerase activity in genitourinary small cell carcinoma and is in keeping with the findings in primary lung locations.

Comparison of telomerase activity in bladder carcinoma and exfoliated cells collected in urine and bladder washings, using a quantitative assay

Telomerase activity was measured with a quantitative assay, based on a modification of telomeric repeat amplification protocol method, in bladder cancers and apparently normal mucosa in 33 patients. In the same patients, the enzyme was also measured in exfoliated cells collected both with voided urine and bladder washings. Results obtained in urine were compared with those from 20 healthy subjects. Telomerase activity was present in 31 (94%) bladder cancer tissues and in 23 (72%) apparently normal mucosa samples. However, the levels of enzyme activity were significantly higher in cancer tissues in comparison with normal mucosa (mean +/- SD, 47.3 +/- 23.2 and 14.9 +/- 6.1 ng DNA/microg protein, respectively; P < 0.0001). Telomerase activity in bladder cancer tissues was not related to tumor stage and grade. Enzyme activity was present in 27 urine samples and in 27 (82%) bladder washings collected from cancer patients. We did not find correlation between the activity in urine and washings, and their mean levels were not different (22.2 +/- 10.1 and 20.7 +/- 8.0, respectively). Telomerase activity in bladder cancer tissues was correlated to its activity in urine (r = 0.650, P < 0.001) and in bladder washings (r = 0.410, P < 0.05). Only 2 of 20 urine samples from control subjects were found to express telomerase activity at a very low level. This was the first attempt to correlate telomerase activity in exfoliated cells from urine and bladder washings with the activity in corresponding bladder cancers. According to these results we postulate that telomerase activity in urine sediment reflects the activity in bladder cancers better than bladder washings and, for its easy collection, is to be preferred as diagnostic marker in this tumor.

Telomerase activity is significantly enhanced in malignant adrenocortical tumors in comparison to benign adrenocortical adenomas

Telomerase is an enzyme that causes short repeated sequence addition to the ends of chromosomes, thereby preventing their shortening during cell division and counteracting cell senescence. Telomerase activity is generally absent in adult differentiated cells, whereas it has been demonstrated in tumor cells, suggesting that its presence might be considered an index of malignancy. To evaluate whether telomerase might be considered a good predictive index of malignancy in adrenocortical tumors, we measured telomerase activity in 11 adrenal adenomas and 7 carcinomas obtained at surgery, using an original quantitative method. Telomerase activity was significantly higher (P<0.001) in carcinomas than in adenomas (median, 15.2 ng DNA/microg protein; range, 9.0-27.6 vs. 2.0; range, 0-8.3), and no overlap was observed between the 2 groups. In carcinomas, telomerase activity was significantly correlated with tumor diameter (r = 0.939; P<0.0001), whereas in adenomas it was not. The results of this study suggest that quantitative telomerase measurement may represent a useful tool to differentiate malignant from benign adrenocortical tumors.

Rapid, quantitative nonisotopic assay for telomerase activity in human tumors

Telomerase is a ribonucleoprotein enzyme that adds TTAGGG repeats onto human telomeres, preventing their shortening. The activation of this enzyme is an important step in cell immortalization and carcinogenesis and seems to represent a new and promising marker in cancer diagnosis and management. Telomerase activity is usually detected in cellular protein extract by the telomeric repeat amplification protocol (TRAP) assay, which can provide only a qualitative (presence/absence) evaluation. Here we present a modification of this method that can provide quantitative information without requiring time-consuming post-PCR procedures such as gel electrophoresis with radioactive materials and autoradiography. The detection and measurement of telomerase activity is performed by evaluating the amount of double-stranded DNA generated in the telomerase reaction and PCR amplification, with the use of the sensitive DNA fluorescent dye PicoGreen. In a subset of tumors, the presence of telomerase activity was confirmed by the conventional TRAP assay. By this method we evaluated telomerase activity in unselected groups of breast (n = 15), ovarian (n = 12), endometrial (n = 12), gastric (n = 20), and renal (n = 12) carcinomas, in meningiomas (n = 8), and in pheochromocitomas (n = 10). The results indicate substantial differences of telomerase activity among cancer groups; however, a large variability among patients of the same group is observed. Kidney, ovarian, and breast carcinomas showed the highest mean values (31.8 +/- 28.9, 29.2 +/- 26.7, and 35.3 +/- 15.9 ng DNA/microg protein, respectively, mean +/- SD), whereas gastric and endometrial cancers had a lower activity (17.2 +/- 8.8 and 13.5 +/- 7.9 ng DNA/microg protein, respectively). Very low or no detectable telomerase activity was found in meningiomas (with the exception of one malignant atypical variant) and pheochromocitomas (9.7 +/- 12.9 and 2.8 +/- 2.1 ng DNA/microg protein, respectively). In conclusion, our method seems to be an accurate and reasonable procedure for measuring telomerase activity in human cancers.

Quantitative polymerase chain reaction-based homogeneous assay with fluorogenic probes to measure c-erbB-2 oncogene amplification

We describe a PCR-based assay for determining c-erbB-2 oncogene amplification in breast cancer in which we use the TaqMan system. Two fluorogenic probes anneal to the target between primers for c-erbB-2 and beta-globin genes and contain both a reporter dye (6-carboxy-fluorescein) and a quencher dye (6-carboxy-tetramethyl-rhodamine). During the extension phase of the PCR cycle, the 5'-->3' exonuclease activity of Taq polymerase cleaves the hybridized fluorogenic probe, resulting in an increase of fluorescence emission of the reporter dye that is quantitative for the amount of PCR product and, under appropriate conditions, for the amount of template. Assay performance showed adequate precision and a lower detection limit and good correlation with the results obtained in the same samples by a competitive PCR assay (n = 25, r = 0.94, P < 0.01). This homogeneous assay is time-saving, avoids usually cumbersome postamplification procedures (that can be additional sources of inaccuracy and contamination), and seems suitable for determination of c-erbB-2 oncogene amplification in tumor specimens.

Gene amplification for c-erbB-2, c-myc, epidermal growth factor receptor, int-2, and N-myc measured by quantitative PCR with a multiple competitor template

We recently proposed a quantitative PCR procedure for the absolute measurement of c-erbB-2 oncogene amplification, based on the simultaneous polymerase chain reaction (PCR) amplification of the target gene and of a competitor DNA molecule acting as internal standard. To increase the number of assayable oncogenes and the accuracy of the quantitative comparison of gene amplification degree within the same tumor, we have now constructed a single synthetic competitor for int-2, c-myc, N-myc epidermal growth factor receptor, and c-erbB-2 genes, and for the reference gene beta-globin. This competitor was constructed by a two-step recombinant PCR procedure and inserted as a 297-bp sequence in a plasmid. The order of primer insertion was designed to obtain competitors of comparable sizes to those of the respective genomic targets, but still easily recognizable from the latter ones by gel electrophoresis. The clone competitor was tested to evaluate the linearity range for each assay. The present application of quantitative PCR based on a multiple competitor represents the first approach for the achievement of a single reagent for the evaluation of a panel of genes potentially amplified in human tumors.

Gene amplification for c-erbB-2, c-myc, epidermal growth factor receptor, int-2, and N-myc measured by quantitative PCR with a multiple competitor template

We recently proposed a quantitative PCR procedure for the absolute measurement of c-erbB-2 oncogene amplification, based on the simultaneous polymerase chain reaction (PCR) amplification of the target gene and of a competitor DNA molecule acting as internal standard. To increase the number of assayable oncogenes and the accuracy of the quantitative comparison of gene amplification degree within the same tumor, we have now constructed a single synthetic competitor for int-2, c-myc, N-myc epidermal growth factor receptor, and c-erbB-2 genes, and for the reference gene beta-globin. This competitor was constructed by a two-step recombinant PCR procedure and inserted as a 297-bp sequence in a plasmid. The order of primer insertion was designed to obtain competitors of comparable sizes to those of the respective genomic targets, but still easily recognizable from the latter ones by gel electrophoresis. The clone competitor was tested to evaluate the linearity range for each assay. The present application of quantitative PCR based on a multiple competitor represents the first approach for the achievement of a single reagent for the evaluation of a panel of genes potentially amplified in human tumors.

Chimeric receptors as a tool for luminescent measurement of biological activities of steroid hormones

Some applications of chimeric cellular models are presented to study the biological activities of steroid hormones. We have used several chimeric constructs encoding the DNA binding domain of Gal4 yeast protein fused to the hormone binding domain of various steroid receptors (MR, PR, GR and ER). Interactions of these chimeric receptors with a 17-mer DNA sequence, specific for Gal-4, control expression of the firefly luciferase as a reporter gene. Stable transfected cell lines expressing the firefly luciferase under the control of different steroids were established and an efficient and easy sub-cloning was allowed with the help of an imaging system using a single-photon-counting camera. In the cell lines obtained, the bioluminescent response can be easily measured and thus used to measure specific biological activities of steroid agonists or antagonists. We observed that the responses are effector-concentration-dependent and their biological activities will be compared to those of native receptors.

Image analysis in quantitative PCR. An application for the measurement of c-erbB-2 oncogene amplification in DNA from human tumours

We present an application of image analysis for the direct quantification of PCR products after gel electrophoresis and ethidium bromide staining of DNA. This procedure has been applied to the development of an assay based on competitive PCR for the measurement of the degree of amplification of c-erbB-2 oncogene in DNA from human tumours. In this method two DNA species (genomic and competitor) compete for PCR amplification. Since results are calculated from the final competitor/genomic ratio any variable affecting the rate of PCR amplification has no effect on the accuracy of the ratio measurement. Results are reported which show that even large variations in the experimental conditions (number of PCR cycles, sample volumes and extracted DNA quality) did not interfere with the precision of the measurement of the competitor/genomic ratio.

Measuring c-erbB-2 oncogene amplification in fresh and paraffin-embedded tumors by competitive polymerase chain reaction

We present an original application of competitive polymerase chain reaction (PCR) for measuring oncogene amplification in DNA from human tumors by simultaneous PCR amplification of genomic DNA with fixed amounts of an internal standard (competitor DNA). Competitors share the same sequence as the target genes but contain an additional 15- to 20-base-pair insert, which allows resolution of the amplified products after polyacrylamide gel electrophoresis and ethidium bromide staining. The gene copy number is derived from the ratio between the intensities of the bands corresponding to the amplified products. Using this procedure, we measured c-erbB-2 amplification in breast and bladder carcinomas in both fresh tumor tissues and paraffin-embedded tissue samples and assessed the precision, sensitivity, and accuracy of the assay. Competitive PCR is a simple, reliable, and accurate method for the evaluation of c-erbB-2 amplification and is potentially suitable for use in the clinical laboratory.

Measuring c-erbB-2 oncogene amplification in fresh and paraffin-embedded tumors by competitive polymerase chain reaction

We present an original application of competitive polymerase chain reaction (PCR) for measuring oncogene amplification in DNA from human tumors by simultaneous PCR amplification of genomic DNA with fixed amounts of an internal standard (competitor DNA). Competitors share the same sequence as the target genes but contain an additional 15- to 20-base-pair insert, which allows resolution of the amplified products after polyacrylamide gel electrophoresis and ethidium bromide staining. The gene copy number is derived from the ratio between the intensities of the bands corresponding to the amplified products. Using this procedure, we measured c-erbB-2 amplification in breast and bladder carcinomas in both fresh tumor tissues and paraffin-embedded tissue samples and assessed the precision, sensitivity, and accuracy of the assay. Competitive PCR is a simple, reliable, and accurate method for the evaluation of c-erbB-2 amplification and is potentially suitable for use in the clinical laboratory.