Slight Overexpression Research Articles

Immunologic Heterogeneity in 2 Cartilage-Hair Hypoplasia Patients With a Distinct Clinical Course.

Cartilage-hair hypoplasia (CHH) syndrome is a rare autosomal recessive syndrome associated with skeletal dysplasia, varying degrees of combined immunodeficiency (CID), short stature, hair hypoplasia, macrocytic anemia, increased risk of malignancies, and Hirschsprung disease. To provide clinical and immunological insights obtained from 2 unrelated patients who displayed clinical characteristics of CHH. Two patients with suspected CHH syndrome due to skeletal dysplasia and immunodeficiency underwent an immunological and genetic work-up using flow cytometry, next-generation sequencing (NGS) of the immune repertoire, and Sanger sequencing to identify the underlying defects. Patient 1 presented with low birth weight and skeletal dysplasia. Newborn screening was suggestive of T-cell immunodeficiency, as T-cell receptor excision circle levels were undetectable. Both the T-cell receptor (TCR) Vß and TCR-g (TRG) repertoires were restricted, with evidence of clonal expansion. Genetic analysis identified compound heterozygous RMRP variants inherited from both parents. Patient 2 presented with recurrent lung and gastrointestinal infections, skeletal dysplasia, failure to thrive, and hepatomegaly. The polyclonal pattern of the TCRß repertoire was normal, with only slight overexpression of TCR-ßV20 and restricted expression of Vßs. TRG expressed a normal diverse repertoire, similar to that of the healthy control sample. Genetic analysis identified biallelic novel regulatory variants in RMRP. Both parents are carriers of this mutation. Our findings demonstrate how the immunological work-up, supported by genetic findings, can dramatically change treatment and future outcome in patients with the same clinical syndrome.

OR04-3 Genetic Alterations of ARMC5 and KDM1A Are Associated With Different Expression Profiles of Illegitimate Receptors in Primary Bilateral Macronodular Adrenal Hyperplasia

Abstract Introduction Primary Bilateral Macronodular Adrenal Hyperplasia (PBMAH) is a heterogeneous disease characterized by bilateral adrenal macronodules responsible for adrenal Cushing. To date, two genetic causes of PBMAH are known: germline inactivating variants of the tumor suppressor genes ARMC5 identified in 2013 (Assié, N Eng J Med 2013), responsible for 20 to 25% of index cases, and KDM1A, identified recently (Vaczlavik, GIM 2021; Chasseloup, Lancet D&E 2021), responsible for the rare presentation associated with food-dependent Cushing's syndrome (FDCS) due to aberrant expression of the GIP receptor (GIPR) in adrenocortical cells. Multiple other illegitimate receptors are known to be responsible for abnormal cortisol response to various physiological stimuli in PBMAH. A recent multiomic analysis, identified three distinct molecular PBMAH groups: G1 with ARMC5-mutated tumors, G2 with KDM1A-mutated tumors from FDCS patients, and G3 with no identified genetic cause at present. We aimed to identify specific expression profiles of illegitimate receptors in the three groups. Methods Based on the transcriptome data obtained by RNA sequencing (Illumina) of the tumors from 31 patients (G1/ARMC5, 16 patients; G2/KDM1A, 6 patients; G3, 9 patients), expression of the following genes, encoding potential illegitimate receptors, were compared: ADRA1A, ADRA1B, ADRA1D, ADRA2A, ADRA2B, ADRA2C, ADRB1, ADRB2, ADRB3, AVPR1A, AVPR1B, AVPR2, GCGR, GIPR, HTR4, HTR7, LHCGR. Calculations were performed using R statistical software. The Bioconductor limma package was used to analyze mRNA differential expression. Results G1/ARMC5 tumors showed a relative overexpression of the vasopressin receptors AVPR1A and AVPR1B compared to the two other groups (fold-change [FC] =7.39, p<0.001 and 3.98, p<0.001, respectively) but a lower expression of AVPR2 (FC=0.43, p=0.015). G2/KDM1A tumors showed a dramatic overexpression of GIPR compared to the two other groups (FC=105.02, p<0.001) but also of the adrenergic receptors ADRA1D and ADRA2A (FC=2.93, p=0.027 and 9.99, p<0.001, respectively) and of the LH/hCG receptor (LHCGR) (FC=12.20, p<0.001). G3 tumors showed a slight overexpression of the adrenergic receptor ADRA1B (FC=3.49, p=0.001) and in few tumors ADRA1D, AVPR2 and LHCGR were highly expressed suggesting molecular heterogeneity in G3. Conclusion This study reveals specific expression profiles of illegitimate receptors related to the three molecular groups. ARMC5 tumors are associated with the overexpression of two vasopressin receptors, while, besides GIPR, KDM1A inactivation seems to drive the overexpression of the LH/hCG receptor, as previously suggested in patients with FDCS (Bertherat, JCE&M 2005), potentially responsible for Cushing's syndrome associated with pregnancy and menopause. These molecular patterns need to be corroborated by clinical data with a systematic testing of the aberrant cortisol responses. Additionally, further studies would be needed to investigate the clinical relevance and significance of moderate fold-changes in gene expression (e.g. <4). Presentation: Saturday, June 11, 2022 12:00 p.m. - 12:15 p.m.

Tumor Microenvironment Stimuli-Responsive Single-NIR-Laser Activated Synergistic Phototherapy for Hypoxic Cancer by Perylene Functionalized Dual-Targeted Upconversion Nanoparticles.

Although synergistic therapy has shown great promise for effective treatment of cancer, the unsatisfactory therapeutic efficacy of photothermal therapy/photodynamic therapy is resulted from the absorption wavelength mismatch, tumor hypoxia, photosensitizer leakage, and inability in intelligent on‐demand activation. Herein, based on the characteristics of tumor microenvironment (TME), such as the slight acidity, hypoxia, and overexpression of H2O2, a TME stimuli‐responsive and dual‐targeted composite nanoplatform (UCTTD‐PC4) is strategically explored by coating a tannic acid (TA)/Fe3+ nanofilm with good biocompatibility onto the upconversion nanoparticles in an ultrafast, green and simple way. The pH‐responsive feature of UCTTD‐PC4 remains stable during the blood circulation, while rapidly releases Fe3+ in the slightly acidic tumor cells, which results in catalyzing H2O2 to produce O2 and overcoming the tumor hypoxia. Notably, the emission spectrum of the UCTTD perfectly matches the absorption spectrum of the photosensitizer (perylene probe (PC4)) to achieve the enhanced therapeutic effect triggered by a single laser. This study provides a new strategy for the rational design and development of the safe and efficient single near‐infrared laser‐triggered synergistic treatment platform for hypoxic cancer under the guidance of multimodal imaging.

PKM2 Is Overexpressed in Glioma Tissues, and Its Inhibition Highly Increases Late Apoptosis in U87MG Cells With Low-density Specificity.

Pyruvate kinase M2 (PKM2) functions as an important rate-limiting enzyme in aerobic glycolysis and is involved in tumor initiation and progression. However, there are few studies on the correlation between PKM2 expression and its role in glioma. PKM2 expression was immunohistochemically examined in human brain tumor samples. Furthermore, we studied the effects of two PKM2 inhibitors (shikonin and compound 3K) on the U87MG glioma cell line. PKM2 was overexpressed in most glioma tissues when compared to controls. Interestingly, glioma-adjacent tissues from showed slight PKM2 overexpression. This suggests that PKM2 overexpression maybe an important trigger factor for glioma tumorigenesis. We found that the PKM2 inhibitor shikonin was effective against U87MG cells at a relatively low dose and was largely dependent on low cellular density compared to the effects of the anticancer drug vincristine. Shikonin highly increased late-apoptosis of U87MG cells. We also demonstrated that autophagy was involved in the increase in late-apoptosis levels caused by shikonin. Although vincristine treatment led to a high level of G2-phase arrest in U87MG cells, shikonin did not increase G2 arrest. Co-treatment with two PKM2 inhibitors, shikonin and compound 3K, increased the inhibitory effects. Combination therapy with PKM2 inhibitors together might be more effective than combination therapy with anticancer drugs. Our findings encourage the application of PKM2-targeting in gliomas, and lay the foundation for the development of PKM2 inhibitors as promising antitumor agents for glioma.

Monitoring and molecular profiling of contemporary insecticide resistance status of malaria vectors in Guinea–Bissau

Despite reduction in the prevalence of malaria, Guinea-Bissau (GB) is still widely affected by the disease that is primarily vectored by Anopheles gambiae s.l. mosquitoes. Monitoring mosquito susceptibility and investigating the insecticide resistance status is an integral part of malaria control actions. Here, mosquito populations from five regions of GB: Bafatá, Bissau, Buba, Cacheu and Gabu were monitored for species ID and insecticide resistance, using diagnostic and intensity WHO bioassays, as well as molecular assays. Phenotypic and molecular identification of species showed the presence of An. gambiae s.s. (S form), An. coluzzii (M form) and An. arabiensis, as well as rare An. arabiensis/ An. gambiae hybrids. Resistance to permethrin and deltamethrin was found in all Anopheles populations assayed, with the intensity of resistance for permethrin being moderate to high, as confirmed by bioassays performed at concentration intensities of 5X and 10X. Consistent to these findings, molecular analysis showed a higher frequency of knock-down resistance (kdr) mutations (L1014F, L1014S, reaching > 90% in some areas) compared to previous studies in the same region, as well as detected for the first time the presence of the super kdr mutation (N1575Y) in GB. The “iAche” (G119S) resistance mutation was also found in GB in low frequencies (up to 12.41%). Additionally, the synergistic PBO-permethrin bioassays suggested partial involvement of non target (metabolic and/or reduced penetration) resistance mechanism. Expression analysis of known pyrethroid metabolisers indicated the slight overexpression and possible association of the cytochrome P450s CYP6Z1, CYP4G16 with the pyrethroid resistance phenotype. The findings should guide future evidence-based resistance management strategies in GB.

Functional characterization and subcellular distribution of two recombinant cytosolic HSP70 isoforms from Entamoeba histolytica under normal and stress conditions.

Amoebiasis is a human intestinal disease caused by the parasite Entamoeba histolytica. It has been previously demonstrated that E. histolytica heat shock protein 70 (EhHSP70) plays an important role in amoebic pathogenicity by protecting the parasite from the dangerous effects of oxidative and nitrosative stresses. Despite its relevance, this protein has not yet been characterized. In this study, the EhHSP70 genes were cloned, and the two recombinant EhHSP70 proteins were expressed, purifying and biochemically characterized. Additionally, after being subjected to some host stressors, the intracellular distribution of the proteins in the parasite was documented. Two amoebic HSP70 isoforms, EhHSP70-A and EhHSP70-B, with 637 and 656 amino acids, respectively, were identified. Kinetic parameters of ATP hydrolysis showed low rates, which were in accordance with those of the HSP70 family members. Circular dichroism analysis showed differences in their secondary structures but similarities in their thermal stability. Immunocytochemistry in trophozoites detected EhHSP70 in the nuclei and cytoplasm as well as a slight overexpression when the parasites were subjected to oxidants and heat. The structural differences of amoebic HSP70s with their human counterparts may be used to design specific inhibitors to treat human amoebiasis.

Xist noncoding RNA could act as a tumor suppressor gene in patients with classical Hodgkin's disease

Xist is a long noncoding RNA involved in the X chromosome inactivation in females. It may act as an onco-suppressor gene in hematologic malignancies, and its activity is strongly dependent from SATB1 gene expression. However, its potential role in Hodgkin's disease (HD) onset and progression is unknown. Three gene expression microarray datasets were analyzed for the expression of Xist and SATB1 in patients with classical HD, namely, GDS4222 (130 patients and 54,000 gene features), GSE39134 (29 patients and 54,000 features), and E-MEXP-507 (29 patients and 27,648 probes). The first two were oligonucleotide arrays (platform: Affymetrix gene chip HG-U133-Plus2), whereas the latter was a cDNA two-channel array (platform: OncoChip. v2). Summary and time-dependent receiver operating characteristic (ROC) analysis were applied to obtain a summary measure (summary area under the ROC curve [sAUC]) of association between gene expression and unfavorable patient outcome in each probe set. Xist was overexpressed among females in each data set. A slight overexpression was associated with a good prognosis both in males (sAUC = 0.75, 95% confidence interval [CI]: 0.70-0.80) and at a lesser extent, in females (sAUC = 0.64, 95% CI: 0.59-0.69). However, this finding was limited to the analysis of the biggest database (GDS4222). No association was found between Xist and SATB1 expression. A reactivation of Xist might act as an onco-suppressor gene in male patients with HD, which seems independent from SATB1 expression. The possibility that Xist could contribute to the better survival of female patients should also be investigated.

Shifting meiotic to mitotic spindle assembly in oocytes disrupts chromosome alignment

Mitotic spindles assemble from two centrosomes, which are major microtubule‐organizing centers (MTOCs) that contain centrioles. Meiotic spindles in oocytes, however, lack centrioles. In mouse oocytes, spindle microtubules are nucleated from multiple acentriolar MTOCs that are sorted and clustered prior to completion of spindle assembly in an “inside‐out” mechanism, ending with establishment of the poles. We used HSET (kinesin‐14) as a tool to shift meiotic spindle assembly toward a mitotic “outside‐in” mode and analyzed the consequences on the fidelity of the division. We show that HSET levels must be tightly gated in meiosis I and that even slight overexpression of HSET forces spindle morphogenesis to become more mitotic‐like: rapid spindle bipolarization and pole assembly coupled with focused poles. The unusual length of meiosis I is not sufficient to correct these early spindle morphogenesis defects, resulting in severe chromosome alignment abnormalities. Thus, the unique “inside‐out” mechanism of meiotic spindle assembly is essential to prevent chromosomal misalignment and production of aneuploidy gametes.

Functional assessment of the BMPR2 gene in lymphoblastoid cell lines from Graves' disease patients.

In this study, we analysed the possible influence of the c.419‐43delT BMPR2 variant in patients with Graves’ disease (GD), in a molecular basis, focusing our efforts on possible alterations in the mRNA processing and synthesis. The molecular assessment of this variant in patients with GD would shed light on the association between the BMPR2 gene and the disease. The variant was detected in 18%, 55% and 10% of patients with pulmonary arterial hypertension, GD and in general population, respectively. Patients with GD fold change showed increased BMPR2 expression when matched against the controls, with a mean of 4.21 ± 1.73 (P = 0.001); BMPR2 was overexpressed in the analysed cell cycle stages. Fold change analysis of variant carriers and non‐carriers showed slight overexpression and differences between phases, but none of them were statistically significant. BMPR2 expression was confirmed in the lymphoblastoid cell lines (LCLs) with a molecular weight of 115 kD, and no differences between variant carriers and non‐carriers were detected. To conclude, the BMPR2 variant c.419‐19delT appears in high frequency in patients with GD, and independently of its presence, BMPR2 is overexpressed in the LCLs from the GD patients tested. This increase could be paired with the described decreased expression of transforming growth factor‐β1 in thyroid tissue from patients with GD.

Absence of Relationship between Mitochondrial DNA Haplogroups and Cisplatin-Induced Hearing Loss.

Background Many drugs used for cancer chemotherapy produce reactive oxygen species, thus leading to various complications including nephrotoxicity, cardiotoxicity, and ototoxicity. Objective We have provided a haplogroup analysis of a cohort of cancer patients treated with chemotherapy and compared factors associated with associated hearing loss. Study Design and Methods This observational cohort study includes a pure-tone audiometry of the patients who underwent chemotherapeutic treatment. Medical history, presence of risk factors for hearing loss, toxic habits, and association with haplogroups have been determined. Results 40% of patients developed hearing loss after administration of cisplatin, which was bilateral and symmetrical and of high frequencies. The most frequent haplogroup was H with a slight overexpression of groups V and K and a low frequency of groups J and T. No association of the haplogroup types with the hearing loss has been found; however age was revealed as an important determining factor. Conclusions Ototoxicity caused by cisplatin is manifested as bilateral, symmetrical, and predominantly high frequency hearing loss. Although we did not find a strong correlation of haplogroups with ototoxicity, our results revealed the existence of a risk group of elderly patients over 60, which are more susceptible to hearing loss induced by cisplatin, than young adults, regardless of preexisting hearing loss.

The Gene Expression Status of the PI3K/AKT/mTOR Pathway in Gastric Cancer Tissues and Cell Lines.

The PI3K/AKT/mTOR pathway plays a crucial role in the regulation of multiple cellular functions including cell growth, proliferation, metabolism and angiogenesis. Emerging evidence has shown that deregulation of this pathway has a role promoting gastric cancer (GC). The aim was to assess the expression of genes involved in this pathway by qPCR in 23 tumor and 23 non-tumor gastric mucosa samples from advanced GC patients, and in AGS, MKN28 and MKN45 gastric cancer cell lines. Results showed a slight overexpression of PIK3CA, PIK3CB, AKT1, MTOR, RPS6KB1, EIF4EBP1 and EIF4E genes, and a slightly decreased PTEN and TSC1 expression. In AGS, MKN28 and MKN45 cells a significant gene overexpression of PIK3CA, PIK3CB, AKT1, MTOR, RPS6KB1 and EIF4E, and a significant repression of PTEN gene expression were observed. Immunoblotting showed that PI3K-β, AKT, p-AKT, PTEN, mTOR, p-mTOR, P70S6K1, p-P70S6K1, 4E-BP1, p-4E-BP1, eIF4E and p-eIF4E proteins were present in cell lines at different levels, confirming activation of this pathway in vitro. This is the first time this extensive panel of 9 genes within PI3K/AKT/mTOR pathway has been studied in GC to clarify the biological role of this pathway in GC and develop new strategies for this malignancy.

A 1 MDa protein complex containing critical components of the Escherichia coli divisome.

Cell division in bacteria is an essential process that is carried out at mid-cell by a group of cell division proteins referred to as the divisome. In Escherichia coli, over two dozen cell division proteins have been identified of which ten are essential. These division proteins localize sequentially and interdependently to the division site, after which constriction eventually produces two daughter cells. Various genetic and biochemical techniques have identified many interactions amongst cell division proteins, however the existence of the divisome as a large multi-protein complex has never been shown. Here, we identify a 1 MDa protein complex by native page that contains seven essential cell division proteins (FtsZ, ZipA, FtsK, FtsQ, FtsB, FtsL, and FtsN). The 1 MDa complex is present in rapidly dividing cells, but absent when cultures enter the stationary growth phase. Slight overexpression of the ftsQ D237N mutation that blocks cell division prevents formation of this 1 MDa complex. In cells depleted of FtsN, the 1 MDa complex is not assembled. Combined, our findings indicate that a large protein complex containing many different cell division proteins indeed exists. We note that this complex is very fragile and sensitive to the expression of tagged versions of FtsQ.

Resistance mechanisms of cancer cells to the novel vacuolar H(+)-ATPase inhibitor archazolid B.

Resistance of cancer cells towards chemotherapy is the major cause of therapy failure. Hence, the evaluation of cellular defense mechanisms is essential in the establishment of new chemotherapeutics. Archazolid B, a novel vacuolar H(+)-ATPase inhibitor, displayed cytotoxicity in the low nanomolar range on a panel of different tumor cell lines. First, we investigated tumor-specific cytotoxicity of archazolid B by comparing cancer to non-cancer cells. Breast, liver and colon cancer cells displayed higher drug sensitivity than corresponding non-tumorous cells, whereas leukemia cell lines were as sensitive as peripheral mononuclear blood cells. Investigating classical drug resistance mechanisms, archazolid B was identified as a possible substrate of the ABC transporters ABCB1 (P-glycoprotein) and ABCG2 (BCRP), whereas collateral sensitivity was observed in ABCB5-expressing cells. Our results pointed to a possible binding competition of archazolid B with verapamil on P-glycoprotein. However, archazolid B did not reverse resistance towards doxorubicin indicating that it might be a substrate but not an inhibitor of P-glycoprotein mediated transport. Furthermore, the cytotoxicity of archazolid B was independent of the p53 status of the cell. Mechanisms of aquired resistance were investigated establishing an archazolid B-resistant MCF-7 cell line. Interestingly, drug resistance was not conferred by aberrant expression or DNA mutations of the gene encoding vacuolar H(+)-ATPase subunit c, the direct target of archazolids. Instead, long-term treatment with archazolid B led to a slight overexpression of ABCB1 and a significant overexpression of the epidermal growth factor receptor and reduced cell growth, all of which can be assumed to contribute to archazolid B resistance.

Tracking of the dynamic localization of the Rab-specific HOPS subunits reveal their distinct interaction with Ypt7 and vacuoles.

Endosomal and vacuole fusion depends on the two homologous tethering complexes CORVET and HOPS. HOPS binds the activated Rab GTPase Ypt7 via two distinct subunits, Vps39 and Vps41. To understand the participation and possible polarity of Vps41 and Vps39 during tethering, we used an in vivo approach. For this, we established the ligand-induced relocalization to the plasma membrane, using the Mon1-Ccz1 GEF complex that activates Ypt7 on endosomes. We then employed slight overexpression to compare the mobility of the HOPS-specific Vps41 and Vps39 subunits during this process. Our data indicate an asymmetry in the Rab-specific interaction of the two HOPS subunits: Vps39 is more tightly bound to the vacuole, and relocalizes the entire vacuole to the plasma membrane, whereas Vps41 behaved like the more mobile subunit. This is due to their specific Rab binding, as the mobility of both subunits was similar in ypt7∆ cells. In contrast, both HOPS subunits were far less mobile if tagged endogenously, suggesting that the entire HOPS complex is tightly bound to the vacuole in vivo. Similar results were obtained for the endosomal association of CORVET, when we followed its Rab-specific subunit Vps8. Our data provide in vivo evidence for distinct Rab specificity within HOPS, which may explain its function during tethering, and indicate that these tethering complexes are less mobile within the cell than previously anticipated.

ABCG2/BCRP gene expression is related to epithelial–mesenchymal transition inducer genes in a papillary thyroid carcinoma cell line (TPC-1)

Tumor malignancy is associated with the epithelial-mesenchymal transition (EMT) process and resistance to chemotherapy. However, little is known about the relationship between the EMT and the multidrug-resistance gene in thyroid tumor progression. We investigated whether the expression of the ABCG2/BCRP gene is associated with ZEB1 and other EMT inducer genes involved in tumor dedifferentiation. We established a subpopulation of cells that express the ABCG2/BCRP gene derived from the thyroid papillary carcinoma cell line (TPC-1), the so-called TPC-1 MITO-resistant subline. The most relevant findings in these TPC-1 selected cells were a statistically significant upregulation of ZEB1 and TWIST1 (35- and 15-fold change respectively), no changes in the relative expression of vimentin and SNAIL1, and no expression of E-cadherin. The TPC-1 MITO-resistant subline displayed a faster migration and greater invasive ability than parental cells in correlation with a significant upregulation of the survivin (BIRC5) gene (twofold change, P<0.05). The knockdown of ZEB1 promoted nuclear re-expression of E-cadherin, reduced expression of vimentin, N-cadherin, and BIRC5 genes, and reduced cell migration (P<0.05). Analysis of human thyroid carcinoma showed a slight overexpression of the ABCG2/BCRP at stages I and II (P<0.01), and a higher overexpression at stages III and IV (P<0.01). SNAIL1, TWIST1, and ZEB1 genes showed higher expression at stages III and IV than at stages I and II. E- and N-cadherin genes were upregulated at stages I and II of the disease (ninefold and tenfold change, respectively, P<0.01) but downregulated at stages III and IV (fourfold lower, P<0.01). These results could be a promising starting point for further study of the role of the ABCG2/BCRP gene in the progression of thyroid tumor.

Quantitative hormone therapy follow-up in an ER+/ERαKD mouse tumor model using FDG and [11C]-methionine PET imaging

BackgroundThe estrogen receptor α (ERα) is known to play an important role in the modulation of tumor response to hormone therapy. In this work, the effect of different hormone therapies on tumors having different ERα expression levels was followed up in vivo in a mouse model by PET imaging using 2-deoxy-2-[18F]fluoro-d-glucose (FDG) and [11C]-methionine ([11C]-MET). A new model of MC7-L1 ERα-knockdown (ERαKD) tumor cell lines was designed as a negative estrogen receptor control to follow up the effects of changes in ERα expression on the early metabolic tumor response to different hormone therapies.MethodsMC7-L1 (ER+) and MC7-L1 ERα-knockdown cell lines were implanted subcutaneously in Balb/c mice and allowed to grow up to 4 mm in diameter. Animals were separated into 4 groups (n = 4 or 5) and treated with a pure antiestrogen (fulvestrant), an aromatase inhibitor (letrozole), a selective estrogen receptor modulator (tamoxifen), or not treated (control). Tumor metabolic activity was assessed by PET imaging with FDG and [11C]-MET at days 0 (before treatment), 7, and 14 after the treatment. Tumor uptake of each radiotracer in %ID/g was measured for each tumor at each time point and compared to tumor growth. Quantitative PCR (qPCR) was performed to verify the expression of breast cancer-related genes (ERα, ErbB2, progesterone receptor (PR), and BRCA1) in each tumor cell lines.ResultsWhile both ER+ and ERαKD tumors had similar uptake of both radiotracers without treatment, higher uptake values were generally seen in ERαKD tumors after 7 and 14 days of treatment, indicating that ERαKD tumors behave in a similar fashion as hormone-unresponsive tumors. Furthermore, the ERα-specific downregulation induced a slight PR expression decrease and overexpression of BRCA1 and ErbB2.ConclusionThe results indicate that the proposed ER+/ERαKD tumor-bearing mouse model is suitable to test pure antiestrogen and aromatase inhibitor therapies in vivo in a preclinical setting and could help to elucidate the impact of ERα levels on tumor response to hormone therapy.

Metalloproteases Could Be Involved in Erythroid Differenciation in MPN

Abstract 5161 BackgroundSeveral hypotheses have been developed to explain how a unique mutation is related to three different phenotypes in Philadephia negative myeloproliferative neoplasms (MPN). Metalloproteases are a group of proteins involved in matrix remodelling, migration and differentiation processes. Although their role has never been studied in MPN, our group has found a differential expression of Matrix metalloproteinase-14 (MMP14) and CD44 between PV and ET JAK2V617F patients (E. Albizua et al, Ann Hematol. 2011Feb). AimsThe purpose of the present study is to validate MMP14 and CD44 differential gene expression profile between PV and ET using a proteomic-based approach and an in vitro model, with the aim of confirming MMP14 and CD44 as MPN biomarkers as well as novel targeted therapy. MethodsSeventy MPN patients diagnosed by WHO criteria were included in the study: 24 Polycythemia Vera (PV) 24 Essential Thrombocythemia (ET) JAK2V617F, 11 ET JAK2 wild type (JAK2WT) and 11 Primary Myelofibrosis (PMF). In addition 24 healthy donors were used as controls.Peripheral blood was analyzed by flow cytometry (FCM) using anti-CD44 and anti-CD45 antibodies in 10 PV and 10 ET. Fifty-five bone marrow biopsies (11 PV, 11 ET JAK2V617F, 11 ET JAK2WT, 11 PMF and 11 healthy controls) were processed to perform immunohistochemistry (IHC) with anti-MMP14 and anti-CD44 antibodies (R&D). Finally an in vitro MPN model was performed. Mononuclear cells from 10 MPN (5 PV and 5 ET) and 5 healthy controls were extracted and seeded in Methocult with IL-3, SCF and EPO. MMP14 was inhibited by Marimastat at 50μM, 25μM and 10μM; and CD44, with anti-CD44 antibody at 10mg/ml, 1mg/ml and 0.1mg/ml. Results were analyzed by BFU-E count, viability study by trypan blue and FCM employing anti-CD45, anti-CD41, anti-CD34, anti-CD71, anti-CD44, and Annexin antibodies. BFU-E DNA was extracted to analyze JAK2V617F allele burden by RT-PCR.Intracellular proteins, including phospho-proteins p38, P-p38, MEK, P-MEK, STAT1, P-STAT1, AKT and P-AKT were studied by cytometric bead array multiplexed bead-based immunoassay (CBAs) technique.The Mann-Whitney non-parametrical statistical hypothesis test was used to assess the statistical significance of our results. ResultsFirst of all, FCM of the granulocytes showed a slight over-expression of CD44 in PV population versus ET.Secondly, IHC also showed MMP14 over-expression in megakaryocites of PV (100% positive patients, 60% positive megakaryocites), and ET (100% positive patients 73% positive megakaryocites) compared to controls (36% positive subjects, 2% positive megakaryocites). Additionally 45% ET JAK2WT were MMP14 positive (20% positive megakaryocites).Significant differences in inhibition of BFU-E growth and cell proliferation were found comparing cultures either under anti-MMP14, Marimastat (50 μM and 25 μM) or under anti-CD44 (10 mg/ml and 1 mg/ml-) to cultures under no inhibitory treatment (P=0.05 and P=0.037 respectively). FCM of BFU-E cultures pointed to a significant decrease of CD71 (erythroid population) with any of the inhibitors.Over-expression of CD44 in PV compared to ET was observed and confirmed in BFU-E by FCM.All phospho-proteins studied halved after anti-CD44 (1 mg/ml) and Marimastat treatments (25 μM). ConclusionsOur results suggest that MMP14 and CD44 could play a role in erythroid differentiation by JAK-STAT, MAPK and AKT pathways. Differences between ET and PV may be caused by both molecules, which may contribute to phenotypic divergence. Additionally, MMP14 IHC could become a useful diagnostic tool in, at least, 45% of ET JAK2WT. Our results suggest that MMP14 and CD44 could become future therapeutic targets and could help to MPN diagnosis. Disclosures:No relevant conflicts of interest to declare.

The RNA Activator ds-p21 Potentiates the Cytotoxicity Induced by Fludarabine in Dohh2 Cells

Recently, it has been reported that, in several tumor cell lines, short double-stranded RNAs tailored for promoter regions of specific genes are able to activate their transcription. Such molecules (named RNA activators) act opposite to other double-stranded RNA molecules (named RNA inhibitors) in that the overexpression instead of underexpression of a given gene is triggered. In Dohh2 non-Hodgkin lymphoma cells, the transcriptional repressor BCL6, which negatively controls both p53 and p21, is overexpressed, so that the cells can escape the check point governed by p53 and proliferate. The aim of this work was to investigate whether the RNA activator p21 can represent a tool to circumvent the transcriptional control of BCL6 and induce the blockage of cell proliferation in Dohh2 non-Hodgkin lymphoma cells. For that, Dohh2 cells were transfected with either a control RNA activator (ds-NC) or an RNA activator specific for human p21 promoter (ds-p21). At various time points after transfection, the cells were collected and p21 was measured. Dohh2 cells transfected with ds-p21 showed a slight but significant overexpression of p21 at both mRNA and protein levels. Nonetheless, cell proliferation, cell cycle, and apoptosis were not significantly modified. In contrast, the exposure of Dohh2 cells transfected with ds-p21 to fludarabine potentiates the cytotoxicity of the drug, suggesting the RNA activator p21 complements the fludarabine-dependent cell death pathways.

Tricellulin, a tight junction protein which reduces permeability for macromolecules or ions depending on its localization in tricellular or bicellular tight junctions

The tight junction protein tricellulin‐a (TRIC‐a) is preferentially localized in tricellular (tTJ), but also in bicellular tight junctions (bTJ). TRIC‐a was cloned and gradually overexpressed into MDCK II cells. Methods included two‐path impedance spectroscopy, permeability measurements for ions and paracellular markers, confocal microscopy, and freeze fracture EM. After slight overexpression, TRIC‐a was localized mainly in tTJ. There, it did not alter paracellular resistance and permeability for mid‐sized solutes, but substantially reduced permeability for macromolecules between 4 and 10 kDa. As demonstrated by life cell imaging microscopy, macromolecular passage occurred across tTJ. In contrast, strong overexpression led to TRIC‐a localization in both, tTJ and bTJ, as a result of which also the paracellular resistance was increased and the permeability for mono‐ and divalent ions was decreased without charge preference. Ultrastructurally, TRIC‐a overexpression in bTJ led to linear bTJ strands and reduced the number of strand breaks. In conclusion, TRIC‐a proves to be a barrier‐forming TJ protein which, if localized in bTJ, consolidates the bTJ strand meshwork and reduces the permeability for ions and mid‐size solutes. However, at its predominant location, the tTJ, the main effect of TRIC‐a is to impede the passage of macromolecules. (Supported by DFG FOR 721)

The gene encoding the splicing factor SF2/ASF is a proto-oncogene

Alternative splicing modulates the expression of many oncogene and tumor-suppressor isoforms. We have tested whether some alternative splicing factors are involved in cancer. We found that the splicing factor SF2/ASF is upregulated in various human tumors, in part due to amplification of its gene, SFRS1. Moreover, slight overexpression of SF2/ASF is sufficient to transform immortal rodent fibroblasts, which form sarcomas in nude mice. We further show that SF2/ASF controls alternative splicing of the tumor suppressor BIN1 and the kinases MNK2 and S6K1. The resulting BIN1 isoforms lack tumor-suppressor activity; an isoform of MNK2 promotes MAP kinase-independent eIF4E phosphorylation; and an unusual oncogenic isoform of S6K1 recapitulates the transforming activity of SF2/ASF. Knockdown of either SF2/ASF or isoform-2 of S6K1 is sufficient to reverse transformation caused by the overexpression of SF2/ASF in vitro and in vivo. Thus, SF2/ASF can act as an oncoprotein and is a potential target for cancer therapy.