PATZ1 Research Articles

Emerging round cell sarcomas in children.

Several distinctive round cell sarcomas have emerged by leveraging new testing modalities to include immunohistochemistry, next-generation sequencing, methylation array, and others. While Ewing sarcoma has led the way as the prototypic round cell sarcoma, more recently described round cell sarcomas of bone and soft tissue are now recognized which have unique clinical, morphologic, immunophenotypic, and genetic signatures. While each of these entities is less common than Ewing sarcoma, it is important to distinguish these tumors for correct diagnosis, prognostication, and potential treatment management. The focus of this review will cover CIC-rearranged sarcoma, BCOR-altered sarcomas, and EWSR1-non-ETS sarcomas to include recent developments in desmoplastic small round cell tumor as well as sarcomas with EWSR1/FUS::NFATc2 and EWSR1::PATZ1 gene fusions, highlighting the clinical, morphologic, and immunophenotypic clues to the diagnosis with recognition of each molecular diagnostic hallmark.

The Imaging Appearance of EWSR1::PATZ1 Gene Fusion Central Nervous System Tumors.

Ewing Sarcoma Breakpoint Region 1 and POZ/BTB And AT Hook Containing Zinc Finger 1 (EWSR1::PATZ1) gene fusion central nervous system (CNS) tumors are increasingly recognized as a potential distinct entity, with only limited reported cases. The imaging characteristics of these tumors have not been well established. In this study, we provide a detailed radiological description of a case in a 24‑year‑old man and conduct a literature review to identify common imaging features. A total of seven cases, including our own, were evaluated. Histopathological diagnoses included two ependymomas, an infantile glioblastoma, an astroblastoma, a ganglioglioma, and two gliomas not otherwise specified. Common imaging patterns included avid contrast enhancement, intratumoral cysts, intraventricular location or extension leading to hydrocephalus, and sharp delineation. Additional frequently observed features included calcifications and hemorrhagic foci. In conclusion, although the histopathological appearance of EWSR1::PATZ1 gene fusion CNS tumors is diverse, there are consistent imaging features. Recognition of these features can be valuable in the diagnostic process, as radiologists can be the first to suggest the diagnosis.

OS11.5.A PATZ1 fusions define a novel molecularly distinct CNS tumor entity with a broad histological spectrum

Abstract BACKGROUND DNA methylation profiling has emerged as a useful tool for robust classification of rare CNS tumors with a broad morphological spectrum. Routine diagnostic molecular profiling performed in Heidelberg and at international collaborating centers revealed a small but recurring number of CNS tumors with fusions of the PATZ1 gene coupled to either MN1 or EWSR1, displaying a distinct genome-wide methylation profile; indicating that these tumors could form a seperate biological entity. MATERIAL AND METHODS We obtained genome-wide DNA-methylation array profiling of 68 primary CNS tumors. RNA-sequencing was perfomed on (n=23/68, 34%) of the tumor samples, including (n=6) from fresh frozen tissue used for gene expression profiling. For n=3 cases, whole exome sequencing (WES) data was generated, and gene panel sequencing data was available for n=13 cases, We systematically reevaluated the histopahthological features of 14 tumors, while immunohistochemical (IHC) staining with Ki-67, GFAP, MAP2, NeuN, Olig-2, Synaptophysin, S-100 and Vimentin was performed for (n=12) tumors. We finally collected clinical data to preliminarily characterize this novel tumor entity. RESULTS A selected analysis of the tumors in this novel cohort (n=68), compared with a reference cohort consisting of 15 other low- and high-grade glial and glioneuronal tumor classes, confirmed a clearly distinct grouping. No similarity was seen with the MN1:BEND2 and MN1:CXXC5-fused CNS-tumors. Analysis of Copy number profiles derived from the DNA-methylation data showed a mostly quite genome, with (n=64/65, 98%) of tumors showing copy number variations on Chromosome 22. RNA-sequencing detected PATZ1 fusions in all tumors sequenced (n=12; MN1:PATZ1, n=11; EWSR1:PATZ1). IGF2, PAX2 and GATA2, all genes involved in brain stem cell biology, were upregulated compared to a combined reference cohort of other glioma subtypes. DNA-sequencing showed no relevant alterations at the level of point mutations or small insertions/deletions. The tumors in our cohort showed polyphenotypic histologies along the glial spectrum, with a subset of tumors being diagnosed as Gliobastoma, WHO Grade 4 and bi- and multiphasic differentaion patterns being evident. IHC performed on tissue available did not favor a particular lineage, with most tumors showing immunopositivity to GFAP. Reverse translation of the gene expression data showed a potential role for NG2 as immunostaining marker. The median age was 11.0 years (0–80), (MN1:PATZ1 manifested at a younger age (median = 4 years) vs EWSR1:PATZ1 (median = 14 years)). Median PFS was 12 months. CONCLUSION We describe here a novel, molecularly distinct CNS tumor class with strikingly variable histopathologic morphology. We postulate that the PATZ1 fusions are a key driver of tumor initiation. Preliminary indications suggest an intermediate prognosis.

PATZ1 Is Overexpressed in Pediatric Glial Tumors and Correlates with Worse Event-Free Survival in High-grade Gliomas.

Glial tumors are the leading cause of cancer-related death and morbidity in children. Their diagnosis, mainly based on clinical and histopathological factors, is particularly challenging because of their high molecular heterogeneity. Thus, tumors with identical histotypes could result in variable biological behaviors and prognoses. The PATZ1 gene has been recently shown to be expressed in adult gliomas, including glioblastomas, where it correlates with the proneural subtype and with a better prognosis. Here, we analyzed the expression of PATZ1 in pediatric gliomas, first at mRNA level in a public database, and then at protein level, by immunohistochemistry, in a cohort of 52 glial brain tumors from young patients aged from 6 months to 16 years. As for adult tumors, we show that PATZ1 is enriched in glial tumors compared to the normal brain, where it correlates positively and negatively with a proneural and mesenchymal signature, respectively. Moreover, we show that PATZ1 is expressed at variable levels in our cohort of tumors. Higher expression was detected in high-grade than low-grade gliomas, suggesting a correlation with the malignancy. Among high-grade gliomas, higher levels of PATZ1 have consistently been found to correlate with worse event-free survival. Therefore, our study may imply new diagnostic opportunities for pediatric gliomas.

Loss of One or Two PATZ1 Alleles Has a Critical Role in the Progression of Thyroid Carcinomas Induced by the RET/PTC1 Oncogene.

POZ/BTB and AT-hook-containing zinc finger protein 1 (PATZ1) is an emerging cancer-related gene that is downregulated in different human malignancies, including thyroid cancer, where its levels gradually decrease going from papillary thyroid carcinomas (PTC) to poorly differentiated and undifferentiated highly aggressive anaplastic carcinomas (ATC). The restoration of PATZ1 expression in thyroid cancer cells reverted their malignant phenotype by inducing mesenchymal-to-epithelial transition, thus validating a tumor suppressor role for PATZ1 and suggesting its involvement in thyroid cancer progression. Here, we investigated the consequences of the homozygous and heterozygous loss of PATZ1 in the context of a mouse modeling of PTC, represented by mice carrying the RET/PTC1 oncogene under the thyroid specific control of the thyroglobulin promoter RET/PTC1 (RET/PTC1TG). The phenotypic analysis of RET/PTC1TG mice intercrossed with Patz1-knockout mice revealed that deficiency of both Patz1 alleles enhanced thyroid cancer incidence in RET/PTC1TG mice, but not the heterozygous knockout of the Patz1 gene. However, both RET/PTC1TG;Patz1+/− and RET/PTC1TG;Patz1−/− mice developed a more aggressive thyroid cancer phenotype—characterized by higher Ki-67 expression, presence of ATCs, and increased incidence of solid variants of PTC—than that shown by RET/PTC1TG; Patz1+/+ compound mice. These results confirm that PATZ1 downregulation has a critical role in thyroid carcinogenesis, showing that it cooperates with RET/PTC1 in thyroid cancer progression.

PATZ1 is a new prognostic marker of glioblastoma associated with the stem-like phenotype and enriched in the proneural subtype.

Glioblastoma (GBM), the most malignant of the brain tumors, has been classified on the basis of molecular signature into four subtypes: classical, mesenchymal, proneural and neural, among which the mesenchymal and proneural subtypes have the shortest and longest survival, respectively. Here we show that the transcription factor PATZ1 gene is upregulated in gliomas compared to normal brain and, among GBMs, is particularly enriched in the proneural subtype and co-localize with stemness markers. Accordingly, in GBM-derived glioma-initiating stem cells (GSCs) PATZ1 is overexpressed compared to differentiated tumor cells and its expression significantly correlates with the characteristic stem cell capacity to grow as neurospheres in vitro. Interestingly, survival analysis demonstrated that PATZ1 lower levels informed poor prognosis in GBM and, specifically, in the proneural subgroup, suggesting it may serve a role as diagnostic and prognostic biomarker for intra-subtype heterogeneity of proneural GBM. We also show that PATZ1 suppresses the expression of the mesenchyme-inducer CXCR4, and that PATZ1 and CXCR4 are inversely correlated in GSC and proneural GBM. Overall these findings support a central role of PATZ1 in regulating malignancy of GBM.

PATZ1 downregulation promotes proliferation and migration in Ras-driven thyroid transformation

PATZ1 downregulation promotes proliferation and migration in Ras-driven thyroid transformation

Embryonic defects and growth alteration in mice with homozygous disruption of thePatz1gene

PATZ1 is an emerging cancer-related gene coding for a POZ/AT-hook/kruppel Zinc finger transcription factor, which is lost or misexpressed in human neoplasias. Here, we investigated its role in development exploring wild-type and Patz1-knockout mice during embryogenesis. We report that the Patz1 gene is ubiquitously expressed at early stages of development and becomes more restricted at later stages, with high levels of expression in actively proliferating neuroblasts belonging to the ventricular zones of the central nervous system (CNS). The analysis of embryos in which Patz1 was disrupted revealed the presence of severe defects in the CNS and in the cardiac outflow tract, which eventually lead to a pre-mature in utero death during late gestation or soon after birth. Moreover, the Patz1-null mice showed a general growth retardation, which was consistent with the slower growth rate and the increased susceptibility to senescence of Patz1(-/-) mouse embryonic fibroblasts (MEFs) compared to wild-type controls. Therefore, these results indicate a critical role of PATZ1 in the control of cell growth and embryonic development.

POZ-, AT-hook-, and Zinc Finger-containing Protein (PATZ) Interacts with Human Oncogene B Cell Lymphoma 6 (BCL6) and Is Required for Its Negative Autoregulation

The PATZ1 gene encoding a POZ/AT-hook/Kruppel zinc finger (PATZ) transcription factor, is considered a cancer-related gene because of its loss or misexpression in human neoplasias. As for other POZ/domain and Kruppel zinc finger (POK) family members, the transcriptional activity of PATZ is due to the POZ-mediated oligomer formation, suggesting that it might be not a typical transactivator but an architectural transcription factor, thus functioning either as activator or as repressor depending on the presence of proteins able to interact with it. Therefore, to better elucidate PATZ function, we searched for its molecular partners. By yeast two-hybrid screenings, we found a specific interaction between PATZ and BCL6, a human oncogene that plays a key role in germinal center (GC) derived neoplasias. We demonstrate that PATZ and BCL6 interact in germinal center-derived B lymphoma cells, through the POZ domain of PATZ. Moreover, we show that PATZ is able to bind the BCL6 regulatory region, where BCL6 itself acts as a negative regulator, and to contribute to negatively modulate its activity. Consistently, disruption of one or both Patz1 alleles in mice causes focal expansion of thymus B cells, in which BCL6 is up-regulated. This phenotype was almost completely rescued by crossing Patz1(+/-) with Bcl6(+/-) mice, indicating a key role for Bcl6 expression in its development. Finally, a significant number of Patz1 knock-out mice (both heterozygous and homozygous) also develop BCL6-expressing lymphomas. Therefore, the disruption of one or both Patz1 alleles may favor lymphomagenesis by activating the BCL6 pathway.

Association of single nucleotide polymorphisms of PATZ1 gene with azoospermia

To study the relationship between the polymorphisms of single nucleotide polymorphisms(SNPs) in rs2240424, rs2057951, rs2240427 and rs714909 loci in the PATZ1 gene and azoospermia. The allele and genotype frequencies of the four SNPs were investigated in 180 patients with azoospermia and 190 normal men as controls by polymerase chain reaction and restriction fragment length polymorphism (PCR-RFLP) analysis. The allele and genotype frequencies of the four SNPs were investigated in 180 patients with azoospermia and 190 normal men as controls by polymerase chain reaction and restriction fragment length polymorphism (PCR-RFLP) analysis. The frequencies of allele C (35.0% vs. 27.6%, P=0.031) and individuals with allele C (TC+CC) (57.8% vs. 46.3%, P=0.027) at the rs2057951 locus in azoospermic patients were significantly higher than that in normal men. There was a significant difference in distribution of haplotypes of the four SNPs between the two groups (P=0.01). Hapoltypes ACAC (11.1% vs. 6.6%, P=0.029) and ACGC (11.2% vs. 5.2%, P=0.003) increased significantly in azoospermic patients compared with controls. The allele C of rs2057951 locus and haplotypes ACAC and ACGC of the four SNPs in PTAZ1 gene increased the susceptibility to azoospermia, suggesting that PATZ1gene may be associated with azoospermia.

PATZ1 gene has a critical role in the spermatogenesis and testicular tumours

PATZ1 is a recently discovered zinc finger protein that, due to the presence of the POZ domain, acts as a transcriptional repressor affecting the basal activity of different promoters. To gain insights into its biological role, we generated mice lacking the PATZ1 gene. Male PATZ1(-/-) mice were unfertile, suggesting a crucial role of this gene in spermatogenesis. Consistently, most of adult testes from these mice showed only few spermatocytes, associated with increased apoptosis, and complete absence of spermatids and spermatozoa, with the subsequent loss of tubular structure. The analysis of PATZ1 expression, by northern blot, western blot and immunohistochemistry, revealed its presence in Sertoli cells and, among the germ cells, exclusively in the spermatogonia. Since PATZ1 has been indicated as a potential tumour suppressor gene, we also looked at its expression in tumours deriving from testicular germ cells (TGCTs). Although expression of PATZ1 protein was increased in these tumours, it was delocalized in the cytoplasm, suggesting an impaired function. These results indicate that PATZ1 plays a crucial role in normal male gametogenesis and that its up-regulation and mis-localization could be associated to the development of TGCTs.