Dynamic relationship among extracellular matrix and body wall cells in Hirudo verbana morphogenesis.

A great bulk of recent experimental evidence suggests the key role of the complex crosstalk between the extracellular matrix (ECM) and the cellular component of tissues during morphogenesis and embryogenesis. In particular, remodeling of the ECM and of its physical interactions pattern with surrounding cells represent two crucial processes that might be involved in muscle development. However, little information is available on this topic, especially on invertebrate species. To obtain new insights on how tuning the ECM microenvironment might drive cellular fate during embryonic development, we used the invertebrate medicinal leech Hirudo verbana as a valuable experimental model, due to its simple anatomy and the recapitulation of many aspects of the basic biological processes of vertebrates. Our previous studies on leech post-embryonic development have already shown the pivotal role of ECM changes during the growth of the body wall and the role of Yes-associated protein 1 (YAP1) in mechanotransduction. Here, we suggest that the interactions between stromal cell telocytes and ECM might be crucial in driving the organization of muscle layers during embryogenesis. Furthermore, we propose a possible role of the pleiotropic enzyme HvRNASET2 as a possible modulator of collagen deposition and ECM remodeling not only during regenerative processes (as previously demonstrated) but also in embryogenesis.

Proline Dehydrogenase (PRODH) Is Expressed in Lung Adenocarcinoma and Modulates Cell Survival and 3D Growth by Inducing Cellular Senescence.

The identification of markers for early diagnosis, prognosis, and improvement of therapeutic options represents an unmet clinical need to increase survival in Non-Small Cell Lung Cancer (NSCLC), a neoplasm still characterized by very high incidence and mortality. Here, we investigated whether proline dehydrogenase (PRODH), a mitochondrial flavoenzyme catalyzing the key step in proline degradation, played a role in NSCLC tumorigenesis. PRODH expression was investigated by immunohistochemistry; digital PCR, quantitative PCR, immunoblotting, measurement of reactive oxygen species (ROS), and functional cellular assays were carried out. PRODH expression was found in the majority of lung adenocarcinomas (ADCs). Patients with PRODH-positive tumors had better cancer-free specific and overall survival compared to those with negative tumors. Ectopic modulation of PRODH expression in NCI-H1299 and the other tested lung ADC cell lines decreased cell survival. Moreover, cell proliferation curves showed delayed growth in NCI-H1299, Calu-6 and A549 cell lines when PRODH-expressing clones were compared to control clones. The 3D growth in soft agar was also impaired in the presence of PRODH. PRODH increased reactive oxygen species production and induced cellular senescence in the NCI-H1299 cell line. This study supports a role of PRODH in decreasing survival and growth of lung ADC cells by inducing cellular senescence.

Transmembrane Protein TMEM230, Regulator of Glial Cell Vascular Mimicry and Endothelial Cell Angiogenesis in High-Grade Heterogeneous Infiltrating Gliomas and Glioblastoma.

High-grade gliomas (HGGs) and glioblastoma multiforme (GBM) are characterized by a heterogeneous and aggressive population of tissue-infiltrating cells that promote both destructive tissue remodeling and aberrant vascularization of the brain. The formation of defective and permeable blood vessels and microchannels and destructive tissue remodeling prevent efficient vascular delivery of pharmacological agents to tumor cells and are the significant reason why therapeutic chemotherapy and immunotherapy intervention are primarily ineffective. Vessel-forming endothelial cells and microchannel-forming glial cells that recapitulate vascular mimicry have both infiltration and destructive remodeling tissue capacities. The transmembrane protein TMEM230 (C20orf30) is a master regulator of infiltration, sprouting of endothelial cells, and microchannel formation of glial and phagocytic cells. A high level of TMEM230 expression was identified in patients with HGG, GBM, and U87-MG cells. In this study, we identified candidate genes and molecular pathways that support that aberrantly elevated levels of TMEM230 play an important role in regulating genes associated with the initial stages of cell infiltration and blood vessel and microchannel (also referred to as tumor microtubule) formation in the progression from low-grade to high-grade gliomas. As TMEM230 regulates infiltration, vascularization, and tissue destruction capacities of diverse cell types in the brain, TMEM230 is a promising cancer target for heterogeneous HGG tumors.

OTX Genes in Adult Tissues.

OTX homeobox genes have been extensively studied for their role in development, especially in neuroectoderm formation. Recently, their expression has also been reported in adult physiological and pathological tissues, including retina, mammary and pituitary glands, sinonasal mucosa, in several types of cancer, and in response to inflammatory, ischemic, and hypoxic stimuli. Reactivation of OTX genes in adult tissues supports the notion of the evolutionary amplification of functions of genes by varying their temporal expression, with the selection of homeobox genes from the "toolbox" to drive or contribute to different processes at different stages of life. OTX involvement in pathologies points toward these genes as potential diagnostic and/or prognostic markers as well as possible therapeutic targets.

Soy diet induces intestinal inflammation in adult Zebrafish: Role of OTX and P53 family.

Inflammatory bowel diseases (IBDs) are a group of inflammatory conditions of the colon and small intestine, including Crohn's disease and ulcerative colitis. Since Danio rerio is a promising animal model to study gut function, we developed a soy-dependent model of intestinal inflammation in adult zebrafish. The soya bean meal diet was given for 4 weeks and induced an inflammatory process, as demonstrated by morphological changes together with an increased percentage of neutrophils infiltrating the intestinal wall, which developed between the second and fourth week of treatment. Pro-inflammatory genes such as interleukin-1beta, interleukin-8 and tumour necrosis factor alpha were upregulated in the second week and anti-inflammatory genes such as transforming growth factor beta and interleukin-10. Interestingly, an additional expression peak was found for interleukin-8 at the fourth week. Neuronal genes, OTX1 and OTX2, were significantly upregulated in the first two  weeks, compatible with the development of the changes in the gut wall. As for the genes of the p53 family such as p53, DNp63 and p73, a statistically significant increase was observed after two weeks of treatment compared with controls. Interestingly, DNp63 and p73 were shown an additional peak after four weeks. Our data demonstrate that soya bean meal diet negatively influences intestinal morphology and immunological function in adult zebrafish showing the features of acute inflammation. Data observed at the fourth week of treatment may suggest initiation of chronic inflammation. Adult zebrafish may represent a promising model to better understand the mechanisms of food-dependent intestinal inflammation.

Spatio-Temporal Changes of Extracellular Matrix (ECM) Stiffness in the Development of the Leech Hirudo verbana.

The invertebrate leech Hirudo verbana represents a powerful experimental animal model for improving the knowledge about the functional interaction between the extracellular matrix (ECM) and cells within the tissue microenvironment (TME), and the key role played by ECM stiffness during development and growth. Indeed, the medicinal leech is characterized by a simple anatomical organization reproducing many aspects of the basic biological processes of vertebrates and in which a rapid spatiotemporal development is well established and easily assessed. Our results show that ECM structural organization, as well as the amount of fibrillar and non-fibrillar collagen are deeply different from hatching leeches to adult ones. In addition, the changes in ECM remodelling occurring during the different leech developmental stages, leads to a gradient of stiffness regulating both the path of migratory cells and their fates. The ability of cells to perceive and respond to changes in ECM composition and mechanics strictly depend on nuclear or cytoplasmic expression of Yes-Associated Protein 1 (YAP1), a key mediator converting mechanical signals into transcriptional outputs, expression, and activation.

Human RNASET2: A Highly Pleiotropic and Evolutionary Conserved Tumor Suppressor Gene Involved in the Control of Ovarian Cancer Pathogenesis.

Ovarian cancer represents one of the most malignant gynecological cancers worldwide, with an overall 5-year survival rate, being locked in the 25-30% range in the last decade. Cancer immunotherapy is currently one of the most intensively investigated and promising therapeutic strategy and as such, is expected to provide in the incoming years significant benefits for ovarian cancer treatment as well. Here, we provide a detailed survey on the highly pleiotropic oncosuppressive roles played by the human RNASET2 gene, whose protein product has been consistently reported to establish a functional crosstalk between ovarian cancer cells and key cellular effectors of the innate immune system (the monocyte/macrophages lineage), which is in turn able to promote the recruitment to the cancer tissue of M1-polarized, antitumoral macrophages. This feature, coupled with the ability of T2 ribonucleases to negatively affect several cancer-related parameters in a cell-autonomous manner on a wide range of ovarian cancer experimental models, makes human RNASET2 a very promising candidate to develop a "multitasking" therapeutic approach for innovative future applications for ovarian cancer treatment.

Hypoxia Enhances the Expression of RNASET2 in Human Monocyte-Derived Dendritic Cells: Role of PI3K/AKT Pathway.

Hypoxia is a key component of the tumor microenvironment (TME) and promotes not only tumor growth and metastasis, but also negatively affects infiltrating immune cells by impairing host immunity. Dendritic cells (DCs) are the most potent antigen-presenting cells and their biology is weakened in the TME in many ways, including the modulation of their viability. RNASET2 belongs to the T2 family of extracellular ribonucleases and, besides its nuclease activity, it exerts many additional functions. Indeed, RNASET2 is involved in several human pathologies, including cancer, and it is functionally relevant in the TME. RNASET2 functions are not restricted to cancer cells and its expression could be relevant also in other cell types which are important players in the TME, including DCs. Therefore, this study aimed to unravel the effect of hypoxia (2% O2) on the expression of RNASET2 in DCs. Here, we showed that hypoxia enhanced the expression and secretion of RNASET2 in human monocyte-derived DCs. This paralleled the HIF-1α accumulation and HIF-dependent and -independent signaling, which are associated with DCs' survival/autophagy/apoptosis. RNASET2 expression, under hypoxia, was regulated by the PI3K/AKT pathway and was almost completely abolished by TLR4 ligand, LPS. Taken together, these results highlight how hypoxia- dependent and -independent pathways shape RNASET2 expression in DCs, with new perspectives on its implication for TME and, therefore, in anti-tumor immunity.

Recombinant HvRNASET2 protein induces marked connective tissue remodelling in the invertebrate model Hirudo verbana.

The RNASET2 ribonuclease, belonging to the highly conserved RH/T2/s RNase gene family, has been recently shown to modulate inflammatory processes in both vertebrates and invertebrates. Indeed, the RNASET2 protein acts as a chemoattractor for macrophages in both in vitro and in vivo experimental settings and its expression significantly increases following bacterial infections. Moreover, we recently observed that injection of human recombinant RNASET2 protein in the body wall of the medicinal leech (a consolidated invertebrate model for both immune response and tissue regeneration) not only induced immune cell recruitment but also apparently triggered massive connective tissue remodelling as well. Based on these data, we evaluate here a possible role of leech recombinant RNASET2 protein (rHvRNASET2) in connective tissue remodelling by characterizing the cell types involved in this process through histochemical, morphological and immunofluorescent assays. Moreover, a time-course expression analysis of newly synthesized pro-collagen1α1 (COL1α1) and basic FGF receptor (bFGFR, a known fibroblast marker) following rHvRNASET2 injection in the leech body wall further supported the occurrence of rHvRNASET2-mediated matrix remodelling. Human MRC-5 fibroblast cells were also investigated in order to evaluate their pattern of collagen neosynthesis driven by rHvRNASET2 injection.Taken together, the data reported in this work provide compelling evidence in support of a pleiotropic role for RNASET2 in orchestrating an evolutionarily conserved crosstalk between inflammatory response and regenerative process, based on macrophage recruitment and fibroblast activation, coupled to a massive extracellular reorganization.

Expression and purification of the human tumor suppressor protein RNASET2 in CHO-S cells.

Members of the T2 extracellular ribonucleases family have long been reported as stress response proteins, often involved in host defence, in many different taxonomic groups. In particular, the human RNASET2 protein (hRNASET2) has been reported as an extracellular tumor suppressor protein, endowed with the ability to act as an "alarmin" signalling molecule following its expression and secretion in the tumor microenvironment by cancer cells and the subsequent recruitment and activation of cells belonging to the host innate immune system. Many in vitro and in vivo assays have been recently reported in support of the oncosuppressive role of hRNASET2: most of them relied on genetically engineered cell lines and the use of recombinant proteins from non-mammalian sources. In order to ensure a human-like glycosylation pattern, here we report for the first time the expression of recombinant hRNASET2 in the CHO-S cell line. We established a simple one-step chromatographic purification procedure that resulted in the production of 5 mg of endotoxin-free hRNASET2 per liter of culture, with a >95% purity degree. hRNASET2 expressed in CHO-S cells displayed a high degree of glycosylation homogeneity and a secondary structure content in agreement with that determined from the crystal structure. Indeed, recombinant hRNASET2 was active at both enzymatic and functional level, as stated by a biological activity assay. The availability of a pure, homogeneous recombinant human RNASET2 would provide a key tool to better investigate its non cell-autonomous roles in the context of cancer development and growth.

3D Reconstruction of HvRNASET2 Molecule to Understand Its Antibacterial Role.

Recent studies performed on the invertebrate model Hirudo verbana (medicinal leech) suggest that the T2 ribonucleic enzyme HvRNASET2 modulates the leech's innate immune response, promoting microbial agglutination and supporting phagocytic cells recruitment in challenged tissues. Indeed, following injection of both lipoteichoic acid (LTA) and Staphylococcus aureus in the leech body wall, HvRNASET2 is expressed by leech type I granulocytes and induces bacterial aggregation to aid macrophage phagocytosis. Here, we investigate the HvRNASET2 antimicrobial role, in particular assessing the effects on the Gram-negative bacteria Escherichia coli. For this purpose, starting from the three-dimensional molecule reconstruction and in silico analyses, the antibacterial activity was evaluated both in vitro and in vivo. The changes induced in treated bacteria, such as agglutination and alteration in wall integrity, were observed by means of light, transmission and scanning electron microscopy. Moreover, immunogold, AMPs (antimicrobial peptides) and lipopolysaccharide (LPS) binding assays were carried out to evaluate HvRNASET2 interaction with the microbial envelopes and the ensuing ability to affect microbial viability. Finally, in vivo experiments confirmed that HvRNASET2 promotes a more rapid phagocytosis of bacterial aggregates by macrophages, representing a novel molecule for counteracting pathogen infections and developing alternative solutions to improve human health.

MCF7 Spheroid Development: New Insight about Spatio/Temporal Arrangements of TNTs, Amyloid Fibrils, Cell Connections, and Cellular Bridges.

Human breast adenocarcinoma cells (MCF7) grow in three-dimensional culture as spheroids that represent the structural complexity of avascular tumors. Therefore, spheroids offer a powerful tool for studying cancer development, aggressiveness, and drug resistance. Notwithstanding the large amount of data regarding the formation of MCF7 spheroids, a detailed description of the morpho-functional changes during their aggregation and maturation is still lacking. In this study, in addition to the already established role of gap junctions, we show evidence of tunneling nanotube (TNT) formation, amyloid fibril production, and opening of large stable cellular bridges, thus reporting the sequential events leading to MCF7 spheroid formation. The variation in cell phenotypes, sustained by dynamic expression of multiple proteins, leads to complex networking among cells similar to the sequence of morphogenetic steps occurring in embryogenesis/organogenesis. On the basis of the observation that early events in spheroid formation are strictly linked to the redox homeostasis, which in turn regulate amyloidogenesis, we show that the administration of N-acetyl-l-cysteine (NAC), a reactive oxygen species (ROS) scavenger that reduces the capability of cells to produce amyloid fibrils, significantly affects their ability to aggregate. Moreover, cells aggregation events, which exploit the intrinsic adhesiveness of amyloid fibrils, significantly decrease following the administration during the early aggregation phase of neutral endopeptidase (NEP), an amyloid degrading enzyme.

Human recombinant RNASET2-induced inflammatory response and connective tissue remodeling in the medicinal leech.

In recent years, several studies have demonstrated that the RNASET2 gene is involved in the control of tumorigenicity in ovarian cancer cells. Furthermore, a role in establishing a functional cross-talk between cancer cells and the surrounding tumor microenvironment has been unveiled for this gene, based on its ability to act as an inducer of the innate immune response. Although several studies have reported on the molecular features of RNASET2, the details on the mechanisms by which this evolutionarily conserved ribonuclease regulates the immune system are still poorly defined. In the effort to clarify this aspect, we report here the effect of recombinant human RNASET2 injection and its role in regulating the innate immune response after bacterial challenge in an invertebrate model, the medicinal leech. We found that recombinant RNASET2 injection induces fibroplasias, connective tissue remodeling and the recruitment of numerous infiltrating cells expressing the specific macrophage markers CD68 and HmAIF1. The RNASET2-mediated chemotactic activity for macrophages has been further confirmed by using a consolidated experimental approach based on injection of the Matrigel biomatrice (MG) supplemented with recombinant RNASET2 in the leech body wall. One week after injection, a large number of CD68+ and HmAIF-1+ macrophages massively infiltrated MG sponges. Finally, in leeches challenged with lipopolysaccharides (LPS) or with the environmental bacteria pathogen Micrococcus nishinomiyaensis, numerous macrophages migrating to the site of inoculation expressed high levels of endogenous RNASET2. Taken together, these results suggest that RNASET2 is likely involved in the initial phase of the inflammatory response in leeches.

Loss of function of Ribonuclease T2, an ancient and phylogenetically conserved RNase, plays a crucial role in ovarian tumorigenesis.

In recent years, the role played by the stromal microenvironment has been given growing attention in order to achieve a full understanding of cancer initiation and progression. Because cancer is a tissue-based disease, the integrity of tissue architecture is a major constraint toward cancer growth. Indeed, a large contribution of the natural resistance to cancer stems from stromal microenvironment components, the dysregulation of which can facilitate cancer occurrence. For instance, recent experimental evidence has highlighted the involvement of stromal cells in ovarian carcinogenesis, as epitomized by ovarian xenografts obtained by a double KO of the murine Dicer and Pten genes. Likewise, we reported the role of an ancient extracellular RNase, called Ribonuclease T2 (RNASET2), within the ovarian stromal microenvironment. Indeed, hyperexpression of RNASET2 is able to control tumorigenesis by recruiting macrophages (mostly of the anticancer M1 subtype) at the tumor sites. We present biological data obtained by RNASET2 silencing in the poorly tumorigenetic and highly RNASET2-expressing human OVCAR3 cell line. RNASET2 knockdown was shown to stimulate in vivo tumor growth early after microinjection of OVCAR3 cells in nude mice. Moreover, we have investigated by molecular profiling the in vivo expression signature of human and mouse cell xenografts and disclosed the activation of pathways related to activation of the innate immune response and modulation of ECM components. Finally, we provide evidence for a role of RNASET2 in triggering an in vitro chemotactic response in macrophages. These results further highlight the critical role played by the microenvironment in RNASET2-mediated ovarian tumor suppression, which could eventually contribute to better clarify the pathogenesis of this disease.

Microenvironmental control of malignancy exerted by RNASET2, a widely conserved extracellular RNase.

A recent body of evidence indicates an active role for stromal (mis)-regulation in the progression of neoplasias. Within this conceptual framework, genes belonging to the growing but still poorly characterized class of tumor antagonizing/malignancy suppressor genes (TAG/MSG) seem to play a crucial role in the regulation of the cross-talk between stromal and epithelial cells by controlling malignant growth in vivo without affecting any cancer-related phenotype in vitro. Here, we have functionally characterized the human RNASET2 gene, which encodes the first human member of the widespread Rh/T2/S family of extracellular RNases and was recently found to be down-regulated at the transcript level in several primary ovarian tumors or cell lines and in melanoma cell lines. Although we could not detect any activity for RNASET2 in several functional in vitro assays, a remarkable control of ovarian tumorigenesis could be detected in vivo. Moreover, the control of ovarian tumorigenesis mediated by this unique tumor suppressor gene occurs through modification of the cellular microenvironment and the induction of immunocompetent cells of the monocyte/macrophage lineage. Taken together, the data presented in this work strongly indicate RNASET2 as a previously unexplored member of the growing family of tumor-antagonizing genes.

Intracellular trafficking of RNASET2, a novel component of P-bodies.

BACKGROUND INFORMATION: The ribonucleases (RNases) constitute a heterogeneous group of enzymes, which exert diverse and specific biological functions. Several RNases have been shown to control gene expression and cell differentiation. RNASET2, a novel member of the Rh/T2/S family of RNases, exerts micro-environmental control of malignancy in different experimental models with a general onco-suppressor activity, since it prevents cancer proliferation. Indeed, RNASET2 was found to be downregulated at the transcript level in several primary ovarian tumours or cell lines and in melanoma cell lines. Although recent works shed light on the biological role of RNASET2 in delaying tumour growth, its trafficking within the cell is still poorly understood. RNASET2 seems to play diverse biological roles including turnover of tRNA in yeast as well as rRNA degradation in zebrafish. RESULTS: Here, we have studied the intracellular trafficking of RNASET2 in mammalian cells. RNASET2 co-localizes with markers for the trans-Golgi network (TGN), which is the central sorting and processing station of the secretory pathway. Moreover, using the temperature-sensitive vesicular stomatitis glycoprotein, we demonstrate that RNASET2 undergoes delivery to the plasma membrane. In contrast to other RNA-interacting proteins, RNASET2 does not accumulate in stress granules upon metabolic stress in mammalian cells. Surprisingly, RNASET2 shows co-localization with processing bodies (P-bodies), which increases upon metabolic stress. Finally, cells lacking RNASET2 show a reduced numbers of P-bodies. CONCLUSIONS: In this study, we have identified two distinct cellular pools of RNASET2-containing granules. One pool undergoes membrane delivery using the TGN, and it is released to the extracellular environment. The second pool is recruited into P-bodies, suggesting a possible involvement of RNASET2 in P-body formation in mammalian cells.

The Potential Role of the T2 Ribonucleases in TME-Based Cancer Therapy.

In recent years, there has been a growing interest in developing innovative anticancer therapies targeting the tumor microenvironment (TME). The TME is a complex and dynamic milieu surrounding the tumor mass, consisting of various cellular and molecular components, including those from the host organism, endowed with the ability to significantly influence cancer development and progression. Processes such as angiogenesis, immune evasion, and metastasis are crucial targets in the search for novel anticancer drugs. Thus, identifying molecules with "multi-tasking" properties that can counteract cancer cell growth at multiple levels represents a relevant but still unmet clinical need. Extensive research over the past two decades has revealed a consistent anticancer activity for several members of the T2 ribonuclease family, found in evolutionarily distant species. Initially, it was believed that T2 ribonucleases mainly acted as anticancer agents in a cell-autonomous manner. However, further investigation uncovered a complex and independent mechanism of action that operates at a non-cell-autonomous level, affecting crucial processes in TME-induced tumor growth, such as angiogenesis, evasion of immune surveillance, and immune cell polarization. Here, we review and discuss the remarkable properties of ribonucleases from the T2 family in the context of "multilevel" oncosuppression acting on the TME.

A potential role of human RNASET2 overexpression in the pathogenesis of Graves' disease.

Genetic variation of the gene encoding for the only human enzyme of the T2 ribonucleases family (RNASET2) emerged in genome-wide association studies as a putative risk hotspot for Graves' disease (GD). T2 ribonucleases activities include immune regulation, induction of cell apoptosis and differentiation. Several reports supported the hypothesis that RNASET2 represents a "danger" message addressed to the innate immune system in peculiar conditions. This was a longitudinal, case-control study. RNASET2 protein levels were assessed in blood samples from 34 consecutive newly diagnosed GD patients and in healthy controls. At enrollment, RNASET2 levels were significantly higher in GD patients (98.5 ± 29.1 ng/ml) compared to healthy controls (72.5 ± 27.9 ng/ml, p = 0.001). After 6 months of methimazole treatment, RNASET2 levels significantly decrease and return to levels similar to healthy controls (62.4 ± 22 ng/ml, p = 0.69). These preliminary results suggest that RNASET2 is overexpressed in patients with GD and might represent an "alarm signal" generated by thyroid cells in response to endogenous or environmental stress to alert the immune system.

Occurrence of L1M Elements in Chromosomal Rearrangements Associated to Chronic Myeloid Leukemia (CML): Insights from Patient-Specific Breakpoints Characterization.

Chronic myeloid leukemia (CML) is a rare myeloproliferative disorder caused by the reciprocal translocation t(9;22)(q34;q11) in hematopoietic stem cells (HSCs). This chromosomal translocation results in the formation of an extra-short chromosome 22, called a Philadelphia chromosome (Ph), containing the BCR-ABL1 fusion gene responsible for the expression of a constitutively active tyrosine kinase that causes uncontrolled growth and replication of leukemic cells. Mechanisms behind the formation of this chromosomal rearrangement are not well known, even if, as observed in tumors, repetitive DNA may be involved as core elements in chromosomal rearrangements. We have participated in the explorative investigations of the PhilosoPhi34 study to evaluate residual Ph+ cells in patients with negative FISH analysis on CD34+/lin- cells with gDNA qPCR. Using targeted next-generation deep sequencing strategies, we analyzed the genomic region around the t(9;22) translocations of 82 CML patients and one CML cell line and assessed the relevance of interspersed repeat elements at breakpoints (BP). We found a statistically higher presence of LINE elements, in particular belonging to the subfamily L1M, in BP cluster regions of both chromosome 22 and 9 compared to the whole human genome. These data suggest that L1M elements could be potential drivers of t(9;22) translocation leading to the generation of the BCR-ABL1 chimeric gene and the expression of the active BCR-ABL1-controlled tyrosine kinase chimeric protein responsible for CML.

Donor Cell Acute Myeloid Leukemia after Hematopoietic Stem Cell Transplantation for Chronic Granulomatous Disease: A Case Report and Literature Review.

The patient reported here underwent hematopoietic stem cell transplantation (HSCT) due to chronic granulomatous disease (CGD) caused by biallelic mutations of the NCF1 gene. Two years later, he developed AML, which was unexpected and was recognized via sex-mismatched chromosomes as deriving from the donor cells; the patient was male, and the donor was his sister. Donor cell leukemia (DCL) is very rare, and it had never been reported in patients with CGD after HSCT. In the subsequent ten years, the AML relapsed three times and the patient underwent chemotherapy and three further HSCTs; donors were the same sister from the first HSCT, an unrelated donor, and his mother. The patient died during the third relapse. The DCL was characterized since onset by an acquired translocation between chromosomes 9 and 11, with a molecular rearrangement between the MLL and MLLT3 genes-a quite frequent cause of AML. In all of the relapses, the malignant clone had XX sex chromosomes and this rearrangement, thus indicating that it was always the original clone derived from the transplanted sister's cells. It exhibited the ability to remain quiescent in the BM during repeated chemotherapy courses, remission periods and HSCT. The leukemic clone then acquired different additional anomalies during the ten years of follow-up, with cytogenetic results characterized both by anomalies frequent in AML and by different, non-recurrent changes. This type of cytogenetic course is uncommon in AML.