Impact of Molecular Biology in Diagnosis, Prognosis, and Therapeutic Management of BCR::ABL1-Negative Myeloproliferative Neoplasm

BCR::ABL1-negative myeloproliferative neoplasms (MPNs) include three major subgroups-polycythemia vera (PV), essential thrombocythemia (ET), and primary myelofibrosis (PMF)-which are characterized by aberrant hematopoietic proliferation with an increased risk of leukemic transformation. Besides the driver mutations, which are JAK2, CALR, and MPL, more than twenty additional mutations have been identified through the use of next-generation sequencing (NGS), which can be involved with pathways that regulate epigenetic modifications, RNA splicing, or DNA repair. The aim of this short review is to highlight the impact of molecular biology on the diagnosis, prognosis, and therapeutic management of patients with PV, ET, and PMF.

PTEN, ATM, IDH1 mutations and MAPK pathway activation as modulators of PFS and OS in patients treated by first line EGFR TKI, an ancillary study of the French Cooperative Thoracic Intergroup (IFCT) Biomarkers France project

OBJECTIVES

Tumor mutation screening is standard of care for patients with stage IV NSCLC. Since a couple of years, widespread NGS approaches used in routine diagnostics to detect driver mutations such as EGFR, KRAS, BRAF or MET allows the identification of other alterations that could modulated the intensity or duration of response to targeted therapies. The prevalence of co-occurring alterations that could affect response or prognosis as not been largely analyzed in clinical settings and large cohorts of patients. Thanks to the IFCT program "Biomarkers France", a collection of samples and data at a nation-wide level was available to test the impact of co-mutations on first line EGFR TKI in patients with EGFR mutated cancers.

MATERIALS AND METHODS

Targeted NGS was assessed on available (n = 208) samples using the Ion AmpliSeq™ Cancer Hotspot Panel v2 to screen for mutations in 50 different cancer genes.

RESULTS

This study showed that PTEN inactivating mutations, ATM alterations, IDH1 mutations and complex EGFR mutations were predictors of short PFS in patients with a stage 4 lung adenocarcinoma receiving first line EGFR TKI and that PTEN, ATM, IDH1 and KRAS mutations as well as alterations in the MAPK pathway were related to shorter OS.

CONCLUSION

These findings may lead to new treatment options in patients with unfavorable genotypes to optimize first line responses.

[Immunohistochemical hormonal mismatch and human epidermal growth factor type 2 [HER2] phenotype of brain metastases in breast cancer carcinoma compared to primary tumors]

INTRODUCTION

Phenotype changes between primary tumor and the corresponding brain metastases are recent reported data. Breast cancer, with biological markers predicting prognosis and guiding therapeutic strategy remains an interesting model to observe and evaluate theses changes. The objective of our study was to compare molecular features (estrogen receptor [ER], progesterone receptor [PR], and human epidermal growth factor receptor type 2, [HER2]) between brain metastases and its primary tumor in patients presenting with pathologically confirmed breast cancer.

MATERIAL AND METHODS

This retrospective study was based on the immunohistochemical analysis of the brain metastases paraffin embedded samples stored in our institutional tumor bank, after surgical resection. The level of expression of hormonal receptors and HER2 on brain metastases were centrally reviewed and compared to the expression status in primary breast cancer from medical records.

RESULTS

Forty-four samples of brain metastases were available for analysis. Hormonal receptor modification status was observed in 11/44 brain metastases (25%) for ER and 6/44 (13.6%) for PR. A modification of HER2 overexpression was observed in brain metastases in 6/44 (13.6%). Molecular subtype modification was shown in 17 cases (38.6%). A significant difference was demonstrated between time to develop brain metastases in cases without status modification (HER2, ER and PR) (med=49.5months [7.8-236.4]) and in cases in which brain metastases status differs from primary tumor (med=27.5months [0-197.3]), (P=0.0244, IC95=3.09-51.62, Mann and Whitney test).

CONCLUSION

the main interest of this study was to focus on the molecular feature changes between primary tumor and their brain metastases. Time to develop brain metastases was correlated to phenotypic changes in brain metastases.

[Oncogenic drivers in daily practice improve overall survival in patients with lung adenocarcinoma]

BACKGROUND

EGFR tyrosine kinase inhibitors and crizotinib are nowadays the optimal treatment for metastatic lung cancer with activation of EGFR mutations and ALK rearrangement. In addition, several targeted agents are in development for lung cancer with other oncodrivers. In France, since 2011, six oncodrivers are routinely tested in patients with stage IV. The aim of this study was to assess whether systematic detection of oncodrivers and matched targeted therapy improve overall survival in patients with advanced lung adenocarcinoma.

METHODS

This study included all consecutive patients treated in our department for advanced lung adenocarcinoma from January 2012 to December 2013. We studied the impact in survival according to the presence of the driver and the targeted therapy.

RESULTS

Among the 261 patients included, oncodrivers alterations were found in 43.5% of patients: EML4-ALK fusion genes (2.1%), EGFR (10.3%), KRAS (27.7%), BRAF (2.5%), HER2 (0.8%), and PI3KCA (0.8%) mutations. Twenty-nine percent of patients (n=32) with oncodrivers received matched targeted therapy. Patient treated by targeted agent appropriate to an oncogenic driver had a median survival of 21.1 months (95% CI: 14.7-27.5). The patients (n=79) who did not receive targeted therapy had a median survival of 6.6 months (95% CI: 4.3-8.9). The patients (n=150) without identified driver had a median survival of 9.7 months (95% CI: 6.7-11.7); P<0.001.

CONCLUSION

An actionable oncodriver was routinely detected in nearly half of patients with advanced lung adenocarcinoma. This systematic detection may influence treatment outcomes, notably with matched targeted therapy.

P4-09-29: A Nomogram To Predict Prognosis in Node-Negative Breast Carcinoma

Background: Currently, the usefulness of conventional markers for breast carcinoma is limited to assess individual outcome. A statistical model was developed to improve the prognostic accuracy using multiple conventional and emerging prognostic biomarkers.

Methods: A total of 305 node-negative breast carcinomas who underwent surgery (+/− radiotherapy) but no adjuvant treatment was selected. Putative prognosis factors including age, tumor size, ER, PR, SBR grading, urokinase plasminogen activator (uPA), plasminogen activator inhibitor type 1 (PAI-1) and thymidine kinase (TK) were evaluated. The developed model was internally validated using Harrell's concordance index and calibrated. An external validation of the new model is warranted.

Results: Age (p&lt;0.001), PR (p= 0.02), and PAI-1(p=&lt;0.001) were included in the Cox regression model predicting overall survival at 5-years. Internal validation revealed a concordance index of 0.711 to 0.694 before and after calibration.

Conclusion: A nomogram can be used to predict probability survival curves for individual breast cancer patients and the effect of treatment options can be evaluated using these models.

Citation Information: Cancer Res 2011;71(24 Suppl):Abstract nr P4-09-29.

Epstein-Barr virus as a marker of biological aggressiveness in breast cancer

Purpose:

Although a potential role of the Epstein-Barr virus (EBV) in the pathogenesis of breast cancer (BC) has been underlined, results remain conflicting. Particularly, the impact of EBV infection on biological markers of BC has received little investigation.

Methods:

In this study, we established the frequency of EBV-infected BC using real-time quantitative PCR (RT–PCR) in 196 BC specimens. Biological and pathological characteristics according to EBV status were evaluated.

Results:

EBV DNA was present in 65 of the 196 (33.2%) cases studied. EBV-positive BCs tended to be tumours with a more aggressive phenotype, more frequently oestrogen receptor negative (P=0.05) and with high histological grade (P=0.01). Overexpression of thymidine kinase activity was higher in EBV-infected BC (P=0.007). The presence of EBV was weakly associated with HER2 gene amplification (P=0.08).

Conclusion:

Our study provides evidence for EBV-associated BC undergoing distinct carcinogenic processes, with more aggressive features.

Correlation of serum urokinase plasminogen activator (uPA) to progression of recurrent malignant glioma during bevacizumab treatment: A marker of invasive phenotype and a candidate to monitor therapy

2059

Background: Identification of circulating markers that predict tumor response or reflect progression is of crucial importance when using antiangiogenic agents. However, to date, no such parameters have been identified particularly for bevacizumab, for which, recently, increasing data have supported a role in patient with recurrent malignant glioma. Methods: Serial serum levels of VEGF, VEGFR2, FGF, SDFα, urokinase plasminogen activator (uPA), plasminogen activator inhibitor type I (PAI-1), and metalloprotesase type 9 (MMP9) were determined in a cohort of 32 patients treated with bevacizumab and irinotecan for recurrent malignant glioma. Samples were collected at the start of treatment and then at 4 weeks intervals until progression. Serum levels were measured using an enzyme-linked immunosorbent assay. Progression was defined by MacDonald's criteria, modified by integrating increase of infiltration as measured on MRI by Flair sequence. All subjects were followed for PFS and OS. Cox model analysis is used for correlation between markers and clinical outcome. Results: This preliminary analysis is restricted to pre-treatment (D0; n = 32), day 30 (D30; n = 27), and at progression time (DP; n = 15). None of the pretreatment serum level (n = 32) significantly affect PFS or OS although uPA and MMP9 tend to influence OS. Decrease of median level of all serum markers except PAI1 and VEGFR2 is observed from D0 to D30 under bevacizumab therapy, but only uPA and FGF variations tend to impact clinical outcome. From D30 to DP, increase of uPA is correlated to PFS (p = 0.028) while the observed increased of FGF and SDFα fail to reach significant correlation to PFS and OS. Conclusions: Increase of uPA serum level appear to be correlated to disease progression for patients with recurrent malignant glioma treated with bevacizumab and may reflect the invasive phenotype of glioma progression. Serum uPA may help in assessing treatment response under bevacizumab and warrant further studies.

No significant financial relationships to disclose.

Adrenomedullin and its receptors expression in renal tumors

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Background: Adrenomedullin (AM) is a 52 amino acid peptide that has an important role on tumor cell proliferation and neoangiogenesis through its receptors CRLR/RAMP2 and CRLR/RAMP3. AM gene expression is stimulated by Hypoxia Inductible Factor-1 (HIF- 1) and 60–80% of the human conventional renal carcinomas (cRCC) display mutations in the tumor suppressor protein von Hippel-Lindau, which leads to constitutively elevated HIF-1. Methods: Tumors and non-malignant kidney tissues were obtained from patients who underwent unilateral nephrectomy. We studied VEGFA, AM and its receptors expression by quantitative RT-PCR in 62 frozen renal tumors including: 40 cRCC; 5 cRCC metastasis; 5 chromophobe carcinomas; 5 Papillary carcinomas; 2 oncocytomas; 2 collecting duct carcinomas; 2 normal adjacent renal tissue; 1 unclassified renal tumor. AM and AM-receptors expression was studied in 42 paraffin-embedded renal tumors by immunohistochemistry using rabbit anti-AM, anti-CRLR, anti-RAMP2 and anti-RAMP3 polyclonal antibodies. Effects of these anti AM or anti AM- receptors antibodies on cell proliferation were examined in vitro on BIZ cell line (cRCC cells). Results: VEGFA, AM and AM-receptors genes were overexpressed in cRCC compared to other renal tumors (Except AM gene in chromophobe carcinoma). Their expressions were independent of classical prognostic factors (such as Fuhrman Grade and pT status). In cRCC, there was a strong positive correlation between VEGF-A gene expression and AM (r=0.7; p=0.01) and AM-receptors genes expressions (RAMP2 r=0.61; p= 0.01 and RAMP3 r=0.58; p= 0.01). Immunohistochemistry confirmed a tumor expression of CRLR, RAMP2 and AM in more than 80% cRCC. RAMP3 was expressed by inflammatory cells but not by tumoral cells. The cell proliferation assay showed a significant inhibition of BIZ cell proliferation by AM antibody or AM-receptors antibodies. Conclusion: AM and its receptor CRLR/RAMP2 are overexpressed in cRCC. In vitro cell proliferation assay results support that AM inhibition may suppress cRCC growth, independently of potential antiangiogenic effects. Further studies on animal models are needed but AM pathway may be a potential therapeutic target in cRCC.

No significant financial relationships to disclose.

Identification of genes differentially expressed in glioblastoma versus pilocytic astrocytoma using Suppression Subtractive Hybridization

Glioblastoma (GBM) is a highly malignant glioma, which has the propensity to infiltrate throughout the brain in contrast to pilocytic astrocytoma (PA) of the posterior fossa, which does not spread and can be cured by surgery. We have used Suppression Subtractive Hybridization to define markers that better delineate the molecular basis of brain invasion and distinguish these tumor groups. We have identified 106 genes expressed in PA versus GBM and 80 genes expressed in GBM versus PA. Subsequent analysis identified a subset of 20 transcripts showing a common differential expression pattern for the two groups. GBM differs from PA by the expression of five genes involved in invasion and angiogenesis: fibronectin, osteopontin, chitinase-3-like-1 (YKL-40), keratoepithelin and fibromodulin. PA differs from GBM by the expression of genes related to metabolism (apolipoprotein D), proteolysis (protease-serine-11), receptor and signal transduction (PLEKHB1 for Pleckstrin-Homology-domain-containing-protein-family-B-member-1), transcription/translation (eukaryotic-translation-elongation-factor-1-alpha1) processes and cell adhesion (SPOCK1 for SPARC/Osteonectin-CWCV-kazal-like-domains-proteoglycan). The expression of these genes was confirmed by real-time quantitative RT-PCR and immunohistochemistry. This study highlights the crucial role of brain invasion in GBM and identifies specific molecules involved in this process. In addition, it offers a restricted list of markers that accurately distinguish PA from GBM.

Characterisation of the gene encoding the alpha-toxin Amm V from the scorpion Androctonus mauretanicus mauretanicus

The full-length cDNA encoding the scorpion alpha-toxin Amm V was amplified from a cDNA library produced from the venom glands of the scorpion Androctonus mauretanicus mauretanicus from Morocco. We deduced the amino acid sequence of the encoded precursor protein and found that the mature toxin was similar to the previously characterised toxin. The genomic DNA sequence encoding the toxin was also amplified, subcloned and sequenced. This also led to the isolation of a new Amm V related-gene. Then, for the first time, we studied changes in the level of toxin mRNA synthesis over time.

The ovine somatostatin receptor subtype 1 (osst1): partial cloning and tissue distribution

The sheep is a valuable model to study GH neuroregulation since its GH secretion pattern is close to that in human. Somatostatin receptor subtype 1 (sst1) appears to be important in central regulation of GH but ovine sst1 (osst1) has not yet been cloned. We report here the cloning of the major part of sst1 in that species. Using human primers from transmembrane domain 2 and 7, we amplified from sheep tissue by RT-PCR a 700 bp fragment. By screening a cDNA sheep library with this fragment, we isolated a 1.4 kb cDNA which contained the major part of the coding cDNA of osst1. The partial predicted protein consists of 347 amino acids exhibiting a putative seven transmembrane domain topology typical of G protein-coupled receptors. Nucleotide sequence comparisons with that of other species showed that osst1 displays 88% homology with human sst1, 84% with rat sst1 and 87% with mouse sst1. Southern blot analysis of ovine cortex DNA demonstrated that osst1 is encoded by a single gene. Northern blot studies evidenced a 3.9 kb transcript highly expressed in the cortex and the hippocampus. This transcript was also present in hypothalamus, striatum, cerebellum, olfactory bulb, spinal cord, brain stem, the lung, kidney, liver, adrenal glands and at a low level in the pituitary gland. No signal was noticeable in the pineal gland. The sequence homology, the tissue distribution, the length of the transcript link this cDNA to the somatostatin receptor family and particularly to sst1.

Frequency and genome load of Epstein-Barr virus in 509 breast cancers from different geographical areas

Since the few data exploring a possible association between Epstein-Barr virus (EBV) and breast cancer are conflicting, we investigated this association together with the influences of geographical areas. 509 breast cancers were sampled from areas with varying risks of nasopharynx carcinoma (NPC) such as North Africa (Algeria and Tunisia, high-risk area); southern France (Marseille, intermediate-risk area); and northern Europe (northern France, the Netherlands and Denmark; low-risk areas). Polymerase chain reaction (PCR) of a subregion of EBV BamHIC encoding the EBERs demonstrated that 31.8% of the tumours contained the viral genome. No significant differences were observed among the geographical areas. However, positive samples showed higher loads of the EBV genome in the NPC high- and intermediate-risk areas than in the low-risk areas. EBV type 1 was the dominant strain. In situ hybridization studies using a(35)S-labelled riboprobe for EBER1 and a laser capture microdissection, combined with quantitative PCR, showed that EBV localization was restricted to some tumour epithelial cell clusters. EBV could not be detected in the stroma. Considering the whole population covered, the presence of the EBV genome was not correlated with age, menopausal status, tumour, size, nodal status or histological grade.

Differential expression and regulation of the vascular endothelial growth factor receptors neuropilin-1 and neuropilin-2 in rat uterus

Vascular endothelial growth factor (VEGF) is a potent modulator of vascular remodeling and angiogenesis in the uterus. Recently, neuropilins (Npn), semaphorin receptors associated with neuronal guidance, were demonstrated to bind VEGF isoforms with high affinity, facilitating VEGF(165) binding to the tyrosine kinase receptor VEGFR2. The current studies examined rat uterus neuropilin expression and regulation. Npn-1 and Npn-2 transcripts and 135-kDa proteins were observed in uterine extracts. Both uterine vascular endothelial cells and glandular epithelium expressed Npn-1 immunoreactivity, whereas Npn-2 was restricted to the glandular epithelium. In hormone-replaced ovariectomized animals, progesterone increased uterine 6.5-kb Npn-1 messenger RNA (mRNA) expression approximately 2-fold compared with that in tissues from ovariectomized controls. 17ss-Estradiol alone had no effect, but blunted the progesterone response; by contrast, Npn-2 mRNA expression was decreased by estrogen. VEGFR2 mRNA was coregulated with Npn-1. Consistent with these results, Npn-1 mRNA expression was augmented nearly 7- and 4-fold at metestrus and diestrus, respectively, during periods of high progesterone; Npn-2 mRNA expression was not significantly altered during the estrous cycle. The regulated expression and differential localization of neuropilins in the rat uterus suggest that these receptors may participate in hormonally regulated changes occurring throughout the female reproductive cycle.

Expression of adrenomedullin and peptide amidation activity in human prostate cancer and in human prostate cancer cell lines

After therapeutic hormone deprivation, prostate cancer (CaP) cells often develop androgen-independent growth through not-well-defined mechanisms. The presence of neuroendocrine (NE) cells is often greater in prostate carcinoma than in normal prostate, and the frequency of NE cells correlates with tumor malignancy, loss of androgen sensitivity, increase of autocrine-paracrine activity, and poor prognosis. In some CaPs, neuropeptides have been previously implicated as growth factors. Peptidylglycine alpha-amidating monooxygenase (PAM) is the enzyme producing alpha-amidated bioactive peptides from their inactive glycine-extended precursors. In the present work, we demonstrate that androgen-independent PC-3 and DU145 cell lines, derived from human CaP, express PAM in vitro and in xenografts implanted in athymic nude mice, indicating that they are able to produce alpha-amidated peptides. Contrarily, barely detectable levels of PAM were found in the androgen-sensitive LNCaP cell line. We also show that whereas PC-3 and DU145 cells produce and secrete adrenomedullin (AM), a multifunctional amidated peptide, no expression was found in LNCaP cells. We further demonstrate that AM acts as a growth factor for DU145 cells, which suggests the existence of an autocrine loop mechanism that could potentially drive neoplastic growth. PAM mRNA levels were found to be 3-fold higher in prostate adenocarcinomas compared with that of human benign prostate hyperplasia (BPH) as demonstrated by real-time quantitative reverse transcription-PCR. The analysis of AM message expression in BPH and CaP (Gleason's score, 6-9) shows a clear distinction between benign and CaP. The expression was detected only in adenocarcinomas tissues with a marked increase in samples with a high Gleason's score. Immunocytochemically, AM was localized in the carcinomatous epithelial compartment. NE phenotype, assessed after the immunocytochemical localization of neuron-specific enolase (NSE), was found in both the epithelial and the stromal compartments of cancers; in BPH, only some spare basal cells were NSE-labeled. Cancer progression could be accelerated by peptides secreted by a population of cells capable of inducing androgen-independent tumoral growth via autocrine-paracrine mechanisms.

Bim-23244, a somatostatin receptor subtype 2- and 5-selective analog with enhanced efficacy in suppressing growth hormone (GH) from octreotide-resistant human GH-secreting adenomas

Although both somatostatin receptor subtype 2 (SSTR2) and SSTR5 messenger ribonucleic acid (mRNA) are consistently expressed in GH-secreting adenomas, SSTR2 has been believed to be the key modulator of somatostatin-mediated inhibition of GH release. The somatostatin agonists currently in clinical use, octreotide and lanreotide, are directed mainly to SSTR2 (IC(50) 12- to 18-fold higher than for SSTR5). Recently, however, it was demonstrated that an SSTR5 preferential agonist, BIM-23268, not only suppressed PRL release from prolactinomas and mixed GH-PRL adenomas, but also inhibited GH release in about half of GH adenomas. In addition, the SSTR5-preferring analog showed a slight additive effect when used in combination with SSTR2 preferential drugs at submaximal concentrations in octreotide partially sensitive adenomas. In the present study we quantified SSTR2 and SSTR5 mRNA expression and the GH-suppressive effects of somatostatin-14; octreotide; a SSTR2-preferential compound, BIM-23197; a SSTR5-preferential compound, BIM-23268; and a new SSTR2- and SSTR5-bispecific compound, BIM-23244, in GH-secreting tumors classified as either full responders to octreotide (n = 5) or partially sensitive to octreotide (n = 5). The octreotide-sensitive GH secretory adenomas presented with a high level of both SSTR2 and SSTR5 mRNA expression [222 +/- 61 and 327 +/- 136 pg/pg glyceraldehyde-3-phosphate dehydrogenase (GAPDH), respectively]. In these tumors the suppression of GH release was similarly achieved at picomolar ranges by octreotide, BIM-23197, and BIM-23244 (EC(50) = 25 +/- 15, 3 +/- 2, and 3 +/- 3 pmol/L, respectively). The compounds preferential for only SSTR5 were unable to inhibit GH release in such tumors. Among the octreotide partially responsive tumors, SSTR2 mRNA expression was 9-fold lower than in the octreotide-sensitive tumors (25 +/- 12 vs. 222 +/- 61 pg/pg GAPDH; P < 0.015), whereas SSTR5 mRNA expression was approximately 7-fold higher than in the octreotide-sensitive tumors (2271 +/- 1197 pg/pg GAPDH). In these octreotide partially responsive tumors, the SSTR5-preferential compound, BIM-23268, and the SSTR2- and SSTR5-bispecific compound, BIM-23244, were quite effective in suppressing GH secretion (EC(50) = 25 +/- 13 and 50 +/- 31 pmol/L, respectively). Similarly, BIM-23244, was able to suppress by 51 +/- 5% PRL release from five mixed GH- and PRL-secreting adenomas. These data indicate that due to heterogeneous expression of SSTR2 and SSTR5 receptor subtypes, in GH-secreting tumors, a bispecific analog, such as BIM-23244, that can activate both receptors could achieve better control of GH hypersecretion in a larger number of acromegalic patients.

Increased expression of the mRNA encoding the somatostatin receptor subtype five in human colorectal adenocarcinoma

Numerous studies have suggested that the antiproliferative potency of somatostatin (SS) analogues may be an efficient tool to improve the prognosis of colorectal cancer. In order to facilitate current efforts to design potent antitumour SS analogues, we studied the distribution of human SS receptors (hsst1-5) mRNAs in a large set of tumoural and normal colonic tissues. Localisation of hsst1-5 mRNAs in normal and tumoural tissues was performed by in situ hybridisation using radioactive antisense or sense riboprobes. Semi-quantitative analysis of hsst5 mRNA was performed using a computerised image analysis system. Hsst binding sites were characterised by studying the relative potency of SS14, SS28 or SS analogues in displacing [(125)I]Tyr degrees -d-Trp(8)-SS14 bound to HT29-D4 cells. Hsst5 mRNA was by far the most expressed subtype in both normal and transformed epithelial cells as well as in the HT29-D4 cell line. An increased expression of hsst5 mRNA was found in tumours. Hsst1 mRNA was expressed preferentially as clusters in immune cells in lamina propria and in stroma close to the tumour. A low expression of hsst4, hsst3 and hsst2 was seen in normal and tumoural tissue. In HT29-D4, binding experiments with SS14 demonstrated the existence of one SS binding class (K(d)=524 nM, B(max)=1fmol/10(6 )cells). In competition binding studies, SS28 and BIM23268 (an analogue that shows preferential specificity towards hsst5) effectively inhibited binding of [(125)I]Tyr degrees -d-Trp(8)-SS14 (IC(50)=15 and 157 nM respectively), while BIM23197 (an analogue that shows preferential affinity for hsst2) was ineffective. Our results show a high expression of hsst5 mRNA in human tumoural colonic tissue, while hsst5 protein is the predominant hsst protein subtype in a tumoural colonic cell line.

Effect of hibernation, thyroid hormones and dexamethasone on cytosolic and mitochondrial glycerol-3-phosphate dehydrogenase from jerboa (Jaculus orientalis)

Tissue distribution of the cytosolic and mitochondrial glycerol-3-phosphate dehydrogenase (cGPDH and mGPDH) activities in jerboa (Jaculus orientalis), a hibernator, shows the highest level of enzyme activity in skeletal muscle and brown adipose tissue, respectively. The effect of hibernation on cGPDH indicates an increase of activity in all tissues examined. In contrast, hibernation decreases mGPDH activity in all tissues, except skeletal muscle. The effect of thyroid hormones on GPDH activity was tissue specific: in kidneys, cGPDH activity doubled in euthermic jerboas treated with T4. In contrast, 6-n-propyl-2-thiouracil treatment provokes an increase of enzyme activity in brown adipose tissue, liver and brain. T4 treatment leads to a 2.7-fold increase in liver mGPDH activity. 6-n-propyl-2-thiouracil treatment decreases mGPDH activity in the skeletal muscle whereas the opposite effect was observed in brain. Dexamethasone stimulates cGPDH in all tissues examined, except skeletal muscle and kidneys. In the case of mGPDH activity, this increase was observed only for brown adipose tissue and brain. Our results suggest that hibernation, thyroid hormones and dexamethasone probably play a role in the regulation of cGPDH and mGPDH activities in jerboa. Our findings confirm that these enzymes are involved in metabolic adaptation to thermal stress in Jaculus orientalis.

Characterization and regulation of peptidylglycine alpha-amidating monooxygenase (PAM) expression in H9c2 cardiac myoblasts

Peptidylglycine alpha-amidating monooxygenase (PAM), which catalazyes the two-step formation of bioactive alpha-amidated peptides from their glycine-extended precursors, has been found in H9c2 myoblasts. The expression of PAM has been evaluated in H9c2 cells. Northern blot analysis and amplification of fragments derived from rat PAM by the reverse transcription/polymerase chain reaction method has demonstrated the presence of rPAM-1, -2, -3, -3a and -3b mRNA transcripts. These forms of PAM mRNA may be generated by alternative splicing. PAM mRNA levels are increased to 160 +/- 12% of control values by treatment with dexamethasone but are unchanged during triiodothyronine incubation of the cells. PAM activity is very low, which is not comparable to the high levels found in adult atrium tissue. Western blot analysis has demonstrated 86-, 76-, and 46-kDa PAM proteins in the particulate fraction. The soluble fraction contains major PAM proteins of 110, 86, and 46 kDa. In situ hybridization studies with 35S-labeled full length RNA antisense transcripts of rat PAM-1 cDNA have localized autoradiographic grains around the nucleus. Our data clearly demonstrate PAM expression in H9c2 rat heart cells, suggesting the ability of these cardiac cells to make bioactive alpha-amidated hormones and/or neuropeptides.

Quantitative and functional expression of somatostatin receptor subtypes in human prolactinomas

Recently, it was demonstrated that somatostatin analogs preferential for the SSTR5 subtype suppress PRL release from prolactinoma cell cultures by 30-40%. These data supported the idea of somatostatin receptor subtype-specific control of PRL secretion in such tumors. The present study examines the quantitative profile of SSTRs messenger ribonucleic acid (mRNA) in 10 PRL-secreting tumors and correlates the expression with the ability of native somatostatins (SS14 and SS28), SSTR2 preferential analogs (octreotide and BIM-23197), and the SSTR5 preferential analog BIM-23268 to suppress PRL secretion. RT-PCR quantitative analysis showed a large predominance of SSTR5 mRNA [5648 +/- 1918 pg/pg glyceraldehyde-3-phosphate dehydrogenase (GAPDH)] vs. SSTR2 mRNA (148 +/- 83 pg/pg GAPDH). The SSTR1 transcript was also highly expressed in prolactinomas (1296 +/- 669 pg/pg GAPDH). SSTR5 mRNA expression correlated with PRL inhibition induced by both SRIF14 and SRIF28. Among the different analogs tested, only BIM-23268 produced inhibition of PRL release similar to that achieved with the native peptides. Its EC50 for PRL suppression was 0.28 +/- 0.10 nmol/L. No additive effects on PRL suppression were achieved by cotreatment of the tumor cells with SSTR2 and SSTR5 preferential analogs. In the same tumor cell cultures, quinagolide, a potent dopamine agonist, produced a dose-dependent inhibition of PRL with an EC50 at least 10 times lower than that of BIM-23268. Coincubation of quinagolide and BIM-23268, particularly in tumor cells resistant to dopamine agonist treatment, did not produce additive effects on PRL suppression. In conclusion, prolactinomas have a specific pattern of SSTR subtype mRNA expression (SSTR5 and SSTR1). SSTR5 expression is correlated to PRL regulation. These inhibitory effects are superimposable, at a higher concentration, to those of the dopamine agonists, but are not additive, particularly in the adenomas resistant to dopaminergic suppression of PRL release.