Deregulation of the IGF system observed in human tumors indicates a role in malignant cell transformation and in tumor cell proliferation. Although overexpression of the IGF2 and IGF1R genes was ...described in adrenocortical tumors (ACTs), few studies reported their profiles in pediatric ACTs. In this study, the IGF2 and IGF1R expression was evaluated by RT-qPCR according to the patient’s clinical/pathological features in 60 pediatric ACT samples, and IGF1R protein was investigated in 45 samples by immunohistochemistry (IHC). Whole transcriptome and functional assays were conducted after IGF1R inhibition with OSI-906 in NCI-H295A cell line. Significant IGF2 overexpression was found in tumor samples when compared with non-neoplastic samples (P<0.001), significantly higher levels of IGF1R in patients with relapse/metastasis (P=0.031) and moderate/strong IGF1R immunostaining in 62.2% of ACTs, but no other relationship with patient survival and clinical/pathological features was observed. OSI-906 treatment downregulated genes associated with MAPK activity, induced limited reduction of cell viability and increased the apoptosis rate. After 24h, the treatment also decreased the expression of genes related to the steroid biosynthetic process, the protein levels of the steroidogenic acute regulatory protein (STAR), and androgen secretion in cell medium, supporting the role of IGF1R in steroidogenesis of adrenocortical carcinoma cells. Our data showed that the IGF1R overexpression could be indicative of aggressive ACTs in children. However, in vitro treatments with high concentrations of OSI-906 (>1μM) showed limited reduction of cell viability, suggesting that OSI-906 alone could not be a suitable therapy to abolish carcinoma cell growth.
The germline TP53-R337H mutation is strongly associated with pediatric adrenocortical tumors (ACT) in southern Brazil; it has low penetrance and limited tissue specificity in most families and ...therefore is not associated with Li-Fraumeni syndrome. However, other tumor types, mainly breast cancer, have been observed in carriers of several unrelated kindreds, raising the possibility that the R337H mutation may also contribute to breast tumorigenesis in a genetic background-specific context.
We conducted a case-control study to determine the prevalence of the R337H mutation by sequencing TP53 exon 10 in 123 women with breast cancer and 223 age- and sex-matched control subjects from southern Brazil. Fisher's test was used to compare the prevalence of the R337H.
The R337H mutation was found in three patients but in none of the controls (p = 0.0442). Among the carriers, two had familial history of cancer meeting the Li-Fraumeni-like criteria. Remarkably, tumors in each of these three cases underwent loss of heterozygosity by eliminating the mutant TP53 allele rather than the wild-type allele. Polymorphisms were identified within the TP53 (R72P and Ins16) and MDM2 (SNP309) genes that may further diminish TP53 tumor suppressor activity.
These results demonstrate that the R337H mutation can significantly increase the risk of breast cancer in carriers, which likely depends on additional cooperating genetic factors. These findings are also important for understanding how low-penetrant mutant TP53 alleles can differentially influence tumor susceptibility.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Plant aldo-keto reductases of the AKR4C subfamily play key roles during stress and are attractive targets for developing stress-tolerant crops. However, these AKR4Cs show little to no activity with ...previously-envisioned sugar substrates. We hypothesized a structural basis for the distinctive cofactor binding and substrate specificity of these plant enzymes. To test this, we solved the crystal structure of a novel AKR4C subfamily member, the AKR4C7 from maize, in the apo form and in complex with NADP+. The binary complex revealed an intermediate state of cofactor binding that preceded closure of Loop B, and also indicated that conformational changes upon substrate binding are required to induce a catalytically-favorable conformation of the active-site pocket. Comparative structural analyses of homologues (AKR1B1, AKR4C8 and AKR4C9) showed that evolutionary redesign of plant AKR4Cs weakened interactions that stabilize the closed conformation of Loop B. This in turn decreased cofactor affinity and altered configuration of the substrate-binding site. We propose that these structural modifications contribute to impairment of sugar reductase activity in favor of other substrates in the plant AKR4C subgroup, and that catalysis involves a three-step process relevant to other AKRs.
•AKR4C7·NADP+ complex reveals an intermediate state of cofactor binding.•Substrate binding induces a catalytically-favorable conformation of the active-site pocket.•Comparative structural analyses support a three-step mechanism for NADPH attachment.•Molecular adaptations associated with Loop B affect cofactor affinity and substrate-binding site.•Plant AKR4Cs provide a mechanistic basis for the impairment of glucose-reductase activity in this subfamily.
Supratentorial RELA fusion (ST-RELA) ependymomas (EPNs) are resistant tumors without an approved chemotherapeutic treatment. Unfortunately, the molecular mechanisms that lead to chemoresistance ...traits of ST-RELA remain elusive. The aim of this study was to assess RELA fusion-dependent signaling modules, specifically the role of the Hedgehog (Hh) pathway as a novel targetable vulnerability in ST-RELA.
Gene expression was analyzed in EPN from patient cohorts, by microarray, RNA-seq, qRT-PCR, and scRNA-seq. Inhibitors against Smoothened (SMO) (Sonidegib) and Aurora kinase A (AURKA) (Alisertib) were evaluated. Protein expression, primary cilia formation, and drug effects were assessed by immunoblot, immunofluorescence, and immunohistochemistry.
Hh components were selectively overexpressed in EPNs induced by the RELA fusion. Single-cell analysis showed that the Hh signature was primarily confined to undifferentiated, stem-like cell subpopulations. Sonidegib exhibited potent growth-inhibitory effects on ST-RELA cells, suggesting a key role in active Hh signaling; importantly, the effect of Sonidegib was reversed by primary cilia loss. We, thus, tested the effect of AURKA inhibition by Alisertib, to induce cilia stabilization/reassembly. Strikingly, Alisertib rescued ciliogenesis and synergized with Sonidegib in killing ST-RELA cells. Using a xenograft model, we show that cilia loss is a mechanism for acquiring resistance to the inhibitory effect of Sonidegib. However, Alisertib fails to rescue cilia and highlights the need for other strategies to promote cilia reassembly, for treating ST-RELA tumors.
Our study reveals a crucial role for the Hh pathway in ST-RELA tumor growth, and suggests that rescue of primary cilia represents a vulnerability of the ST-RELA EPNs.
Summary
Lymphotoxin‐mediated activation of the lymphotoxin‐β receptor (LTβR; LTBR) has been implicated in cancer, but its role in T‐cell acute lymphoblastic leukaemia (T‐ALL) has remained elusive. ...Here we show that the genes encoding lymphotoxin (LT)‐α and LTβ (LTA, LTB) are expressed in T‐ALL patient samples, mostly of the TAL/LMO molecular subtype, and in the TEL‐JAK2 transgenic mouse model of cortical/mature T‐ALL (Lta, Ltb). In these mice, expression of Lta and Ltb is elevated in early stage T‐ALL. Surface LTα1β2 protein is expressed in primary mouse T‐ALL cells, but only in the absence of microenvironmental LTβR interaction. Indeed, surface LT expression is suppressed in leukaemic cells contacting Ltbr‐expressing but not Ltbr‐deficient stromal cells, both in vitro and in vivo, thus indicating that dynamic surface LT expression in leukaemic cells depends on interaction with its receptor. Supporting the notion that LT signalling plays a role in T‐ALL, inactivation of Ltbr results in a significant delay in TEL‐JAK2‐induced leukaemia onset. Moreover, young asymptomatic TEL‐JAK2;Ltbr−/− mice present markedly less leukaemic thymocytes than age‐matched TEL‐JAK2;Ltbr+/+ mice and interference with LTβR function at this early stage delayed T‐ALL development. We conclude that LT expression by T‐ALL cells activates LTβR signalling in thymic stromal cells, thus promoting leukaemogenesis.
Insulin and insulin-like growth factors (IGFs) are mitogenic and prosurvival factors to many different cell types, including acute lymphoblastic leukemia (ALL). Circulating IGFs are bound by IGF ...binding proteins (IGFBPs) that regulate their action. IGFBP7 is an IGFBP-related protein (IGFBP-rP) that in contrast to other IGFBPs/IGFBP-rPs features higher affinity for insulin than IGFs and was shown to bind the IGF1 receptor (IGF1R) as well. The role of IGFBP7 in cancer is controversial: on some tumors, it functions as an oncogene, whereas in others, it functions as a tumor suppressor. In childhood ALL, higher IGFBP7 expression levels were associated with worse prognosis. Here we show that IGFBP7 exerts mitogenic and prosurvival autocrine effects on ALL cells that were dependent on insulin/IGF. IGFBP7 knockdown or antibody-mediated neutralization resulted in significant attenuation of ALL cell viability in vitro and leukemia progression in vivo. IGFBP7 was shown to prolong the surface retention of the IGF1R under insulin/IGF1 stimulation, resulting in sustained IGF1R, insulin receptor substrate 1 (IRS-1), protein kinase B (AKT), and extracellular signal-regulated kinase (ERK) phosphorylation. Conversely, the insulin receptor was readily internalized and dephosphorylated on insulin stimulation, despite IGFBP7 addition. The affinity of homodimeric IGF1R for insulin is reportedly >100 times lower than for IGF1. In the presence of IGFBP7, however, 25 ng/mL insulin resulted in IGF1R activation levels equivalent to that of 5 ng/mL IGF1. In conclusion, IGFBP7 plays an oncogenic role in ALL by promoting the perdurance of IGF1R at the cell surface, prolonging insulin/IGF stimulation. Preclinical data demonstrate that IGFBP7 is a valid target for antibody-based therapeutic interventions in ALL.
•Physiologic levels of extracellular IGFBP7 prolong the surface expression and activation of IGF1R by insulin/IGF in ALL.•Knockdown or antibody neutralization of IGFBP7 decrease ALL progression in vivo.
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Background
Oral mucositis is a common collateral effect among the secondary complications resulting from chemotherapy. The objective of this study was to prospectively evaluate the association of
...HSV-1
,
Candida
spp., and oral bacteria on the severity of oral mucositis in pediatric acute lymphoblastic leukemia (ALL).
Procedure
Seventy-one prospective patients were included. Analyses of oral microbiota were conducted on days 14 (D14) and 56 (D56) of the Brazilian GBTLI-99 treatment protocol.
Herpes simplex
virus (
HSV
) identification was performed by PCR followed by DNA sequencing analysis. Bacteria and fungi identification was obtained by standard microbiological culture tests.
Results
HSV-1
was found in 10.37% of individual patient samples. One sample was positive for
HSV-4
. On D14, we found an association between the severity of mucositis and the presence of
HSV
(
p =
0.0347) and
Candida
spp. (
p
= 0.0078). At D56, we found an association between the severity of mucositis and the presence of
HSV
on D14 (
p
< 0.0001) and
HSV
presence (
p =
0.0317).
Conclusion
The presence of
HSV
, mainly
HSV-1
, and
Candida
spp. was associated with mucositis severity in pediatric ALL. No association could be found between bacterial CFU and severity of mucositis.
Glioblastoma (GBM) is the most common primary malignant neoplasm of the central nervous system and, despite the standard therapy; the patients’ prognoses remain dismal. The miRNA expression profiles ...have been associated with patient prognosis, suggesting that they may be helpful for tumor diagnosis and classification as well as predictive of tumor response to treatment. We described the microRNA expression profile of 29 primary GBM samples (9 pediatric GBMs) and 11 non-neoplastic white matter samples as controls (WM) by microarray analysis and we performed functional in vitro assays on these 2 most differentially expressed miRNAs. Hierarchical clustering analysis showed 3 distinct miRNA profiles, two of them in the GBM samples and a group consisting only of cerebral white matter. When adult and pediatric GBMs were compared to WM, 37 human miRNAs were found to be differentially expressed, with miR-10b-5p being the most overexpressed and miR-630 the most underexpressed. The overexpression of miR-630 was associated with reduced cell proliferation and invasion in the U87 GBM cell line, whereas the inhibition of miR-10b-5p reduced cell proliferation and colony formation in the U251 GBM cell line, suggesting that these miRNAs may act as tumor-suppressive and oncogenic miRNAs, respectively. The present study highlights the distinct epigenetic profiling of adult and pediatric GBMs and underscores the biological importance of mir-10b-5p and miR-630 for the pathobiology of these lethal tumors.
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