Claudio Ceccarelli

Self-renewal of CD133(hi) cells by IL6/Notch3 signalling regulates endocrine resistance in metastatic breast cancer.

The mechanisms of metastatic progression from hormonal therapy (HT) are largely unknown in luminal breast cancer. Here we demonstrate the enrichment of CD133hi/ERlo cancer cells in clinical specimens following neoadjuvant endocrine therapy and in HT refractory metastatic disease. We develop experimental models of metastatic luminal breast cancer and demonstrate that HT can promote the generation of HT-resistant, self-renewing CD133hi/ERlo/IL6hi cancer stem cells (CSCs). HT initially abrogates oxidative phosphorylation (OXPHOS) generating self-renewal-deficient cancer cells, CD133hi/ERlo/OXPHOSlo. These cells exit metabolic dormancy via an IL6-driven feed-forward ERlo-IL6hi-Notchhi loop, activating OXPHOS, in the absence of ER activity. The inhibition of IL6R/IL6-Notch pathways switches the self-renewal of CD133hi CSCs, from an IL6/Notch-dependent one to an ER-dependent one, through the re-expression of ER. Thus, HT induces an OXPHOS metabolic editing of luminal breast cancers, paradoxically establishing HT-driven self-renewal of dormant CD133hi/ERlo cells mediating metastatic progression, which is sensitive to dual targeted therapy.

Evolution of Cancer Stem-like Cells in Endocrine-Resistant Metastatic Breast Cancers Is Mediated by Stromal Microvesicles

The hypothesis that microvesicle-mediated miRNA transfer converts noncancer stem cells into cancer stem cells (CSC) leading to therapy resistance remains poorly investigated. Here we provide direct evidence supporting this hypothesis, by demonstrating how microvesicles derived from cancer-associated fibroblasts (CAF) transfer miR-221 to promote hormonal therapy resistance (HTR) in models of luminal breast cancer. We determined that CAF-derived microvesicles horizontally transferred miR-221 to tumor cells and, in combination with hormone therapy, activated an ERlo/Notchhi feed-forward loop responsible for the generation of CD133hi CSCs. Importantly, microvesicles from patients with HTR metastatic disease expressed high levels of miR-221. We further determined that the IL6-pStat3 pathway promoted the biogenesis of onco-miR-221hi CAF microvesicles and established stromal CSC niches in experimental and patient-derived breast cancer models. Coinjection of patient-derived CAFs from bone metastases led to de novo HTR tumors, which was reversed with IL6R blockade. Finally, we generated patient-derived xenograft (PDX) models from patient-derived HTR bone metastases and analyzed tumor cells, stroma, and microvesicles. Murine and human CAFs were enriched in HTR tumors expressing high levels of CD133hi cells. Depletion of murine CAFs from PDX restored sensitivity to HT, with a concurrent reduction of CD133hi CSCs. Conversely, in models of CD133neg, HT-sensitive cancer cells, both murine and human CAFs promoted de novo HT resistance via the generation of CD133hi CSCs that expressed low levels of estrogen receptor alpha. Overall, our results illuminate how microvesicle-mediated horizontal transfer of genetic material from host stromal cells to cancer cells triggers the evolution of therapy-resistant metastases, with potentially broad implications for their control. Cancer Res; 77(8); 1927-41. ©2017 AACR.

Good survival outcome of metastatic SDH-deficient gastrointestinal stromal tumors harboring SDHA mutations

Purpose:A subset of patients with KIT/PDGFRA wild-type gastrointestinal stromal tumors show loss of function of succinate dehydrogenase, mostly due to germ-line mutations of succinate dehydrogenase subunits, with a predominance of succinate dehydrogenase subunit A. The clinical outcome of these patients seems favorable, as reported in small series in which patients were individually described. This work evaluates a retrospective survival analysis of a series of patients with metastatic KIT/PDGFRA wild-type succinate dehydrogenase–deficient gastrointestinal stromal tumors.Methods:Sixty-nine patients with metastatic gastrointestinal stromal tumors were included in the study (11 KIT/PDGFRA wild-type, of whom 6 were succinate dehydrogenase deficient, 5 were non–succinate dehydrogenase deficient, and 58 were KIT/PDGFRA mutant). All six succinate dehydrogenase–deficient patients harbored SDHA mutations. Kaplan–Meier curves and log-rank tests were used to compare the survival of patients with succinate dehydrogenase subunit A–mutant gastrointestinal stromal tumors with that of KIT/PDGFRA wild-type patients without succinate dehydrogenase deficiency and patients with KIT/PDGFRA-mutant gastrointestinal stromal tumors.Results:Follow-up ranged from 8.5 to 200.7 months. The difference between succinate dehydrogenase subunit A–mutant gastrointestinal stromal tumors and KIT/PDGFRA-mutant or KIT/PDGFRA wild-type non–succinate dehydrogenase deficient gastrointestinal stromal tumors was significant considering different analyses (P = 0.007 and P = 0.033, respectively, from diagnosis of gastrointestinal stromal tumor for the whole study population; P = 0.005 and P = 0.018, respectively, from diagnosis of metastatic disease for the whole study population; P = 0.007 for only patients who were metastatic at diagnosis).Conclusion:Patients with metastatic KIT/PDGFRA wild-type succinate dehydrogenase–deficient gastrointestinal stromal tumors harboring succinate dehydrogenase subunit A mutations present an impressively long survival. These patients should be identified in clinical practice to better tailor treatments and follow-up over time.Genet Med 17 5, 391–395.

A mutation screening of oncogenes, tumor suppressor gene TP53 and nuclear encoded mitochondrial complex I genes in oncocytic thyroid tumors

BackgroundThyroid neoplasias with oncocytic features represent a specific phenotype in non-medullary thyroid cancer, reflecting the unique biological phenomenon of mitochondrial hyperplasia in the cytoplasm. Oncocytic thyroid cells are characterized by a prominent eosinophilia (or oxyphilia) caused by mitochondrial abundance. Although disruptive mutations in the mitochondrial DNA (mtDNA) are the most significant hallmark of such tumors, oncocytomas may be envisioned as heterogeneous neoplasms, characterized by multiple nuclear and mitochondrial gene lesions. We investigated the nuclear mutational profile of oncocytic tumors to pinpoint the mutations that may trigger the early oncogenic hit.MethodsTotal DNA was extracted from paraffin-embedded tissues from 45 biopsies of oncocytic tumors. High-resolution melting was used for mutation screening of mitochondrial complex I subunits genes. Specific nuclear rearrangements were investigated by RT-PCR (RET/PTC) or on isolated nuclei by interphase FISH (PAX8/PPARγ). Recurrent point mutations were analyzed by direct sequencing.ResultsIn our oncocytic tumor samples, we identified rare TP53 mutations. The series of analyzed cases did not include poorly- or undifferentiated thyroid carcinomas, and none of the TP53 mutated cases had significant mitotic activity or high-grade features. Thus, the presence of disruptive TP53 mutations was completely unexpected. In addition, novel mutations in nuclear-encoded complex I genes were identified.ConclusionsThese findings suggest that nuclear genetic lesions altering the bioenergetics competence of thyroid cells may give rise to an aberrant mitochondria-centered compensatory mechanism and ultimately to the oncocytic phenotype.

Genome-Wide Analysis Identifies MEN1 and MAX Mutations and a Neuroendocrine-Like Molecular Heterogeneity in Quadruple WT GIST

Quadruple wild-type (WT) gastrointestinal stromal tumor (GIST) is a genomic subgroup lacking KIT/PDGFRA/RAS pathway mutations, with an intact succinate dehydrogenase (SDH) complex. The aim of this work is to perform a wide comprehensive genomic study on quadruple WT GIST to improve the characterization of these patients. We selected 14 clinical cases of quadruple WT GIST, of which nine cases showed sufficient DNA quality for whole exome sequencing (WES). NF1 alterations were identified directly by WES. Gene expression from whole transcriptome sequencing (WTS) and miRNA profiling were performed using fresh-frozen, quadruple WT GIST tissue specimens and compared with SDH and KIT/PDGFRA-mutant GIST. WES identified an average of 18 somatic mutations per sample. The most relevant somatic oncogenic mutations identified were in TP53, MEN1, MAX, FGF1R, CHD4, and CTDNN2. No somatic alterations in NF1 were identified in the analyzed cohort. A total of 247 mRNA transcripts and 66 miRNAs were differentially expressed specifically in quadruple WT GIST. Overexpression of specific molecular markers (COL22A1 and CALCRL) and genes involved in neural and neuroendocrine lineage (ASCL1, Family B GPCRs) were detected and further supported by predicted miRNA target analysis. Quadruple WT GIST show a specific genetic signature that deviates significantly from that of KIT/PDGFRA-mutant and SDH-mutant GIST. Mutations in MEN1 and MAX genes, a neural-committed phenotype and upregulation of the master neuroendocrine regulator ASCL1, support a genetic similarity with neuroendocrine tumors, with whom they also share the great variability in oncogenic driver genes. Implications: This study provides novel insights into the biology of quadruple WT GIST that potentially resembles neuroendocrine tumors and should promote the development of specific therapeutic approaches. Mol Cancer Res; 15(5); 553–62. ©2017 AACR.

JHDM1B expression regulates ribosome biogenesis and cancer cell growth in a p53 dependent manner.

Tumors characterized by an intense ribosome biogenesis often display a more aggressive behavior. Ribosomal RNA (rRNA) synthesis is controlled at several levels, including the epigenetic regulation of the condensation of chromatin portions containing rRNA genes. JHDM1B (Jumonji C histone demethylase 1B) is a histone demethylase able to regulate the accessibility of rRNA genes. In this study, we aimed to define the contribution of JHDM1B expression to the features of breast cancer, a tumor type whose behavior is related to the rate of ribosome biogenesis. We show that, in breast cancer‐derived cell lines, the increase in rRNA transcription that follows JHDM1B knock‐down is mirrored by an augmented cell proliferation only in p53 compromised cells, while p53 competent cells undergo cellular senescence and death. The latter effect appears to be mediated by a p38‐dependent phosphorylation of p53, inducing the expression of p15Ink4b and p21Waf1. In breast cancers, lower JHDM1B expression correlates with an increased size of specifically stained nucleolar organized regions, a morphological parameter directly related to the rate of ribosome biogenesis and with a poorer prognosis. In addition, in tumors lacking the controller function of p53, a lower expression of JHDM1B is associated with an increased tumor size at diagnosis. Altogether, our data indicate that epigenetic activation of rDNA genes induced by JHDM1B depletion is associated with a p53‐dependent growth arrest, but may promote cancer cell growth when p53 is lacking.

HER2 isoforms co-expression differently tunes mammary tumor phenotypes affecting onset, vasculature and therapeutic response

Full-length HER2 oncoprotein and splice variant Delta16 are co-expressed in human breast cancer. We studied their interaction in hybrid transgenic mice bearing human full-length HER2 and Delta16 (F1 HER2/Delta16) in comparison to parental HER2 and Delta16 transgenic mice. Mammary carcinomas onset was faster in F1 HER2/Delta16 and Delta16 than in HER2 mice, however tumor growth was slower, and metastatic spread was comparable in all transgenic mice. Full-length HER2 tumors contained few large vessels or vascular lacunae, whereas Delta16 tumors presented a more regular vascularization with numerous endothelium-lined small vessels. Delta16-expressing tumors showed a higher accumulation of i.v. injected doxorubicin than tumors expressing full-length HER2. F1 HER2/Delta16 tumors with high full-length HER2 expression made few large vessels, whereas tumors with low full-length HER2 and high Delta16 contained numerous small vessels and expressed higher levels of VEGF and VEGFR2. Trastuzumab strongly inhibited tumor onset in F1 HER2/Delta16 and Delta16 mice, but not in full-length HER2 mice. Addiction of F1 tumors to Delta16 was also shown by long-term stability of Delta16 levels during serial transplants, in contrast full-length HER2 levels underwent wide fluctuations. In conclusion, full-length HER2 leads to a faster tumor growth and to an irregular vascularization, whereas Delta16 leads to a faster tumor onset, with more regular vessels, which in turn could better transport cytotoxic drugs within the tumor, and to a higher sensitivity to targeted therapeutic agents. F1 HER2/Delta16 mice are a new immunocompetent mouse model, complementary to patient-derived xenografts, for studies of mammary carcinoma onset, prevention and therapy.Full-length HER2 oncoprotein and splice variant Delta16 are co-expressed in human breast cancer. We studied their interaction in hybrid transgenic mice bearing human full-length HER2 and Delta16 (F1 HER2/Delta16) in comparison to parental HER2 and Delta16 transgenic mice. Mammary carcinomas onset was faster in F1 HER2/Delta16 and Delta16 than in HER2 mice, however tumor growth was slower, and metastatic spread was comparable in all transgenic mice. Full-length HER2 tumors contained few large vessels or vascular lacunae, whereas Delta16 tumors presented a more regular vascularization with numerous endothelium-lined small vessels. Delta16-expressing tumors showed a higher accumulation of i.v. injected doxorubicin than tumors expressing full-length HER2. F1 HER2/Delta16 tumors with high full-length HER2 expression made few large vessels, whereas tumors with low full-length HER2 and high Delta16 contained numerous small vessels and expressed higher levels of VEGF and VEGFR2. Trastuzumab strongly inhibited tumor onset in F1 HER2/Delta16 and Delta16 mice, but not in full-length HER2 mice. Addiction of F1 tumors to Delta16 was also shown by long-term stability of Delta16 levels during serial transplants, in contrast full-length HER2 levels underwent wide fluctuations. In conclusion, full-length HER2 leads to a faster tumor growth and to an irregular vascularization, whereas Delta16 leads to a faster tumor onset, with more regular vessels, which in turn could better transport cytotoxic drugs within the tumor, and to a higher sensitivity to targeted therapeutic agents. F1 HER2/Delta16 mice are a new immunocompetent mouse model, complementary to patient-derived xenografts, for studies of mammary carcinoma onset, prevention and therapy.

Mitochondrial DNA sequencing demonstrates clonality of peritoneal implants of borderline ovarian tumors

Borderline ovarian tumors are rare low malignant potential neoplasms characterized by the absence of stromal invasion, whose main prognostic factors are stage and type of peritoneal implants. The latter are defined as invasive when cell proliferation invades the underlying tissue (peritoneal surface, omentum and intestinal wall), or noninvasive. It is still unknown if these implants are metastatic spread from the primary ovarian mass or a neoplastic transformation de novo of the peritoneal surface. Mitochondrial DNA sequencing was performed to assess clonality in eight patients presenting both borderline ovarian tumors and implants. In 37.5% of the cases, the same mitochondrial DNA mutation was present in both borderline ovarian tumors and the peritoneal implant, being this evidence that implants may arise as a consequence of a spread from a single ovarian site.

Determination of Mammalian Target of Rapamycin Hyperactivation as Prognostic Factor in Well-Differentiated Neuroendocrine Tumors

Purpose To evaluate the role of the activation of mTOR (phosphorylated mTOR, p-mTOR) and the expression SSTR2A and IGF-1R as prognostic factor in well-differentiated neuroendocrine tumors. Methods A retrospective study was conducted on data from patients with diagnosis of neuroendocrine tumor originated from pancreas (pNET) or gastrointestinal tract (stomach, appendix, and ileus; GI-NET) made between January 2003 and December 2004 and followed up at our institution. Archival material should be available for revision according to WHO 2010 neuroendocrine tumor classification and for p-mTOR, SSTR2A, and IGF-1R immunostaining, calculating a quantitative score (QS). We evaluated clinical, pathological, and immunohistochemistry features for association with the presence of advanced disease at diagnosis and disease relapse in patients who have undergone radical surgery. Results Archival material from 64 patients was analyzed (37 pNETs and 27 GI-NETs). In these patients, G2 grading, low SSTR2A QS, and high p-mTOR QS were associated with advanced disease at diagnosis at multivariate analysis. Risk of recurrence in 49 patients with R0-resected tumors was higher for G2 grading, stage IIIB-IV, low IGF-1R QS, and high p-mTOR QS at univariate analysis. Conclusions With the limits of retrospective data, activation of m-TOR is correlated with advanced disease at diagnosis and with shorter disease-free survival after R0 resection. Validation through prospective studies is needed.

Successful treatment with personalized dosage of imatinib in elderly patients with gastrointestinal stromal tumors.

Imatinib is the standard first-line therapy for metastatic gastrointestinal stromal tumors. It has markedly improved the prognosis and outcome of patients affected by gastrointestinal stromal tumors, especially in the case of exon 11 KIT mutations. Imatinib-associated adverse events are generally mild to moderate; however, in clinical practice, intolerance caused by chronic toxicities frequently leads to breaks in treatment. This is particularly true in elderly patients in whom age, decline in drug metabolism, and polypharmacy, with a possible drug–drug interaction, may influence the tolerability of imatinib. In the present article, we report our extensive experience with the management of imatinib therapy in a ‘real’ population, in particular in very elderly patients, discussing whether the use of personalized imatinib dosage could be a safe and advantageous option, enabling continuous administration, thus ensuring effective treatment. Only a few case reports in the literature provide data on outcome with low tailored dosage of imatinib and none of them has been carried out on a Western population. Here, we report four cases treated with low imatinib dosage as a safe and useful option enabling continued treatment with imatinib, improving tolerance, and maintaining good and lasting disease control.