HMGA1 and HMGA2 rearrangements in mass-forming endometriosis

Xanthogranulomatous epithelial tumors and keratin-positive giant cell-rich soft tissue tumors: two aspects of a single entity with frequent HMGA2-NCOR2 fusions

Xanthogranulomatous epithelial tumor (XGET) and keratin-positive giant cell-rich soft tissue tumor with HMGA2-NCOR2 fusion (KPGCT) are two recently described neoplasms with both distinct and overlapping clinical and histopathologic features. We hypothesized that XGET and KPGCT may be related and represent a histologic spectrum of a single entity. To test this, we sought to characterize the clinical, radiographic, immunohistochemical, ultrastructural and molecular features of additional tumors with features of XGET and/or KPGCT, which we refer to descriptively as keratin-positive xanthogranulomatous/giant cell-rich tumors (KPXG/GCT). The archives were searched for potential cases of KPXG/GCT. Clinical and imaging features were noted. Slides were assessed for histologic and immunohistochemical findings. Ultrastructural and next generation RNA sequencing-based analysis were also performed. Nine cases were identified arising in seven women and two men [median age of 33 years (range: 12-87)]. Median tumor size was 4 cm (range: 2.4-14.0 cm) and tumors presented in the thigh (2), buttock (1), forearm (2), groin (1), cranial fossa (1), ilium (1), and tibia (1). Morphologically, tumors were most frequently characterized by a fibrous capsule, with associated lymphoid reaction, enclosing a polymorphous proliferation of histiocytes, giant cells (Touton and osteoclast-types), mixed inflammatory infiltrate, hemorrhage and hemosiderin deposition, which imparted a variably xanthogranulomatous to giant cell tumor-like appearance. One case clearly showed mononuclear cells with eosinophilic cytoplasm characteristic of XGET. All cases expressed keratin and 7 of 9 were found to harbor HMGA2-NCOR2 fusions including cases with xanthogranulomatous appearance. One patient developed local recurrence and multifocal pulmonary lesions, which were radiographically suspicious for metastases. Shared clinical, histologic and immunohistochemical features, and the shared presence of HMGA2-NCOR2 fusions supports interpretation of KPXG/GCT as a single entity which includes XGET and KPGCT. Given limited clinical follow-up to date and rare cases with apparently aggressive findings, we provisionally regard these tumors as having uncertain biologic potential.

Somatic Genomic Events in Endometriosis: Review of the Literature and Approach to Phenotyping

In this review, we provide a survey and appraisal of research into somatic genomic events in endometriosis. Methodologies have evolved from conventional cytogenetics to next-generation sequencing, with findings ranging from chromosome imbalances to recurrent somatic cancer driver mutations. Somatic cancer driver mutations have been described in a range of endometriosis lesions, dominated by recurrent mutations in KRAS and PIK3CA as well as loss of PTEN and BAF250a (ARID1A). These somatic events appear to be largely restricted to the endometriosis glandular epithelium. Somatic mutations, particularly PTEN loss, have also been observed in eutopic (uterine) endometrium, although at lower mutant allele frequencies compared with ectopic lesions. Systematic studies of the potential clinical phenotype of these somatic genomic events have yet to be performed. Thus, we propose a framework to investigate the potential clinical phenotype associated with somatic genomic events in endometriosis. Technical requirements include pathology review of histological endometriosis, microdissection for tissue enrichment, orthogonal validation of whole genome/exome sequencing, and a germline sample for confirmation of somatic origin. Clinical requirements include annotation of surgical findings; patient demographics; cross-sectional and prospective data on pain and fertility; consideration of sampling multiple lesions in each patient, mutant allele frequency, and somatic events in the eutopic endometrium; and confirmation of any associations with mechanistic studies. Given the multifactorial nature of endometriosis-associated symptoms, it is likely that somatic events have small (or at most, moderate) effect sizes, and thus careful consideration will have to be given to future study design.

Loss of stromal CD73 expression plays a role in pathogenesis of polypoid endometriosis

PURPOSE

To investigate whether CD73 had a role in the pathogenesis of polypoid endometriosis.

METHODS

Our study included 15 cases of polypoid endometriosis, which were diagnosed between 2005 and 2019. Clinical findings were gathered from archive files of relevant clinics and pathology reports. All glass slides were re-examined for confirmation of the diagnosis and the detection of additional microscopic findings. An immunohistochemical examination was performed using anti CD73 antibodies in 15 cases of polypoid endometriosis, and also in a control group that contained 9 cases of endometrial polyps and 9 cases of ovarian conventional endometriosis.

RESULTS

In addition to standard gynecologic operations, major non-gynecologic procedures had to be performed in 7 cases. In two cases, the surgical team comprised only general surgeons, and a misdiagnosis of carcinoma was made during the frozen section in one case. The majority of the cases displayed gross polypoid lesions that measured 0.7-13 cm. The most common sites were the ovary and rectosigmoid colon. Microscopically, all lesions exhibited a fibrovascular stroma reminiscent of endometrial stroma, whereas glandular features varied. Immunohistochemical examinations revealed a significant loss of CD73 expression in the stroma of polypoid endometriosis in contrast to the control cases, which retained stromal CD73 expression (p < 0.0001).

CONCLUSION

Both pathologists and surgeons performing abdominal surgeries should be aware of polypoid endometriosis because it mimics malignancy with its clinical, gross, and microscopic features. We also conclude that loss of stromal CD73 expression, due to its effect on the extracellular ATP/adenosine balance, may contribute to the pathogenesis of this rare form of endometriosis.

Genomic profiling of pelvic genital type leiomyosarcoma in a woman with a germline CHEK2:c.1100delC mutation and a concomitant diagnosis of metastatic invasive ductal breast carcinoma

We describe a woman with the known pathogenic germline variant CHEK2:c.1100delC and synchronous diagnoses of both pelvic genital type leiomyosarcoma (LMS) and metastatic invasive ductal breast carcinoma. CHEK2 (checkpoint kinase 2) is a tumor-suppressor gene encoding a serine/threonine-protein kinase (CHEK2) involved in double-strand DNA break repair and cell cycle arrest. The CHEK2:c.1100delC variant is a moderate penetrance allele resulting in an approximately twofold increase in breast cancer risk. Whole-genome and whole-transcriptome sequencing were performed on the leiomyosarcoma and matched blood-derived DNA. Despite the presence of several genomic hits within the double-strand DNA damage pathway (CHEK2 germline variant and multiple RAD51B somatic structural variants), tumor profiling did not show an obvious DNA repair deficiency signature. However, even though the LMS displayed clear malignant features, its genomic profiling revealed several characteristics classically associated with leiomyomas including a translocation, t(12;14), with one breakpoint disrupting RAD51B and the other breakpoint upstream of HMGA2 with very high expression of HMGA2 and PLAG1. This is the first report of LMS genomic profiling in a patient with the germline CHEK2:c.1100delC variant and an additional diagnosis of metastatic invasive ductal breast carcinoma. We also describe a possible mechanistic relationship between leiomyoma and LMS based on genomic and transcriptome data. Our findings suggest that RAD51B translocation and HMGA2 overexpression may play an important role in LMS oncogenesis.

Effect of RNA interference of the expression of HMGA2 on the proliferation and invasion ability of ACHN renal cell carcinoma cells

This aim of the present study was to observe the effect of high mobility group AT-hook 2 (HMGA2) on the proliferation and invasion ability of ACHN renal cell carcinoma (RCC) cells. Human ACHN cells, an RCC cell line, and HKC normal human renal tubular epithelial cells were cultured. HMGA2 small interfering (si)RNA, Mock-siRNA and their negative control group were designed and synthesized. Subsequently, the ACHN cells were transiently transfected using RNA interference technology. Finally, the mRNA and protein expression levels of HMGA2 were detected using reverse transcription-polymerase chain reaction and western blot analyses. The proliferation ability of the ACHN cells was determined using MTT, and ACHN cell invasion ability was detected using the Transwell method. The results showed that the mRNA and protein expression levels of HMGA2 in the ACHN cells were considerably higher, compared with those in the HKC cells (P<0.01). The RCC cells, in which the expression of HMGA2 was specifically silenced, was successfully constructed. The proliferation rate of cells in the HMGA2-siRNA group was significantly lower, compared with that of cells in the Mock-siRNA group and control group at 24, 48, 72 and 96 h post-transfection (P<0.05). The invasion ability of cells in the HMGA2-siRNA group was significantly lower, compared with that of cells in the Mock-siRNA group and control group (P<0.05) 48 h following transfection. Therefore, the HMGA2 gene may function as an oncogene in the occurrence and development of RCC, and provide specific targets for the targeted therapy of RCC. Further detailed investigations of the HMGA2 gene are important for future gene therapy of RCC.

Fusion of the TBL1XR1 and HMGA1 genes in splenic hemangioma with t(3;6)(q26;p21)

RNA-sequencing of a splenic hemangioma with the karyotype 45~47,XX,t(3;6)(q26;p21) showed that this translocation generated a chimeric TBL1XR1-HMGA1 gene. This is the first time that this tumor has been subjected to genetic analysis, but the finding of an acquired clonal chromosome abnormality in cells cultured from the lesion and the presence of the TBL1XR1-HMGA1 fusion in them strongly favor the conclusion that splenic hemangiomas are of a neoplastic nature. Genomic PCR confirmed the presence of the TBL1XR1-HMGA1 fusion gene, and RT-PCR together with Sanger sequencing verified the presence of the fusion transcripts. The molecular consequences of the t(3;6) would be substantial. The cells carrying the translocation would retain only one functional copy of the wild-type TBL1XR1 gene while the other, rearranged allele could produce a putative truncated form of TBL1XR1 protein containing the LiSH and F-box-like domains. In the TBL1XR1-HMGA1 fusion transcript, furthermore, untranslated exons of HMGA1 are replaced by the first 5 exons of the TBL1XR1 gene. The result is that the entire coding region of HMGA1 comes under the control of the TBL1XR1 promoter, bringing about dysregulation of HMGA1. This is reminiscent of similar pathogenetic mechanisms involving high mobility genes in benign connective tissue tumors such as lipomas and leiomyomas.

HMGA2 Expression in Renal Carcinoma and its Clinical Significance

Background

The objective of this study is to detect HMGA2 expression in renal carcinoma to explore its relationship with clinicopathology and its significance in prognosis.

Methods

Expressions of HMGA2 mRNA and protein were detected in 50 renal carcinoma specimens, 50 corresponding adjacent normal kidney tissue samples and 40 renal benign tumour specimens via reverse transcription polymerase chain reaction and immunohistochemical assay. Expression analysis was performed along with clinical data analysis.

Results

The relative expression levels of HMGA2 mRNA in renal carcinoma, renal benign tumour tissues and adjacent normal renal tissues were 0.84±0.23, 0.19±0.06 and 0.08±0.04, respectively. HMGA2 protein positive rates were 68.0%, 7.5% and 2.0%, with a significant difference (P<0.05). HMGA2 expression was not significantly correlated with gender, age, tumour size and histological type (P>0.05), but was significantly correlated with TNM stages and lymph node metastasis (P<0.05).

Conclusions

The expressions of HMGA2 gene and protein in renal carcinoma were closely correlated with tumour formation, progression and metastasis. HMGA2 may become a powerful new pathological marker and prognostic factor for renal carcinoma.

Stromal epigenetic dysregulation is sufficient to initiate mouse prostate cancer via paracrine Wnt signaling

Carcinomas most often result from the stepwise acquisition of genetic alterations within the epithelial compartment. The surrounding stroma can also play an important role in cancer initiation and progression. Given the rare frequencies of genetic events identified in cancer-associated stroma, it is likely that epigenetic changes in the tumor microenvironment could contribute to its tumor-promoting activity. We use Hmga2 (High-mobility group AT-hook 2) an epigenetic regulator, to modify prostate stromal cells, and demonstrate that perturbation of the microenvironment by stromal-specific overexpression of this chromatin remodeling protein alone is sufficient to induce dramatic hyperplasia and multifocal prostatic intraepithelial neoplasia lesions from adjacent naïve epithelial cells. Importantly, we find that this effect is predominantly mediated by increased Wnt/β-catenin signaling. Enhancement of Hmga2-induced paracrine signaling by overexpression of androgen receptor in the stroma drives frank murine prostate adenocarcinoma in the adjacent epithelial tissues. Our findings provide compelling evidence for the critical contribution of epigenetic changes in stromal cells to multifocal tumorigenesis.

Genomic imbalances in benign metastasizing leiomyoma: characterization by conventional karyotypic, fluorescence in situ hybridization, and whole genome SNP array analysis

Benign metastasizing leiomyoma, a rare condition of controversial origin, is characterized by the occurrence of extrauterine smooth muscle tumors primarily affecting the lungs of women with a history of uterine leiomyomas. Numerous genetic studies of uterine leiomyoma with rearrangements of the HMGA2 and HMGA1 loci defined in prominent subgroups have been conducted. In contrast, cytogenetic and molecular descriptions of benign metastasizing leiomyoma are few, and, in particular, this entity has not been previously subjected to single nucleotide polymorphism (SNP) array analysis. In this study, conventional karyotypic, and/or molecular cytogenetic, and SNP array characterization of a pleuropulmonary benign mestasizing leiomyoma and a synchronous deep soft tissue leiomyoma of the thigh, which arose in a 56-year-old female with a remote history of uterine leiomyomata, revealed rearrangement of the HMGA1 (6p21) locus and nearly identical genomic profiles, including loss of chromosome 7 material in both lesions. These findings suggest that both the deep soft tissue and pleuropulmonary lesions were derived from the same abnormal clone and are genetically related to uterine leiomyomata.

Silencing of HMGA1 expression by RNA interference suppresses growth of osteogenic sarcoma

The expression of high mobility group protein A1 (HMGA1) protein has been closely related to various malignant and prognostic degrees of tumor. To investigate the influence of down-regulating HMGA1 on the tumor and the mechanism underlying antitumor of HMGA1, we transfected the HMGA1 shRNA vector into the osteogenic sarcoma MG-63 cell and observed the changes of cell proliferation, invasion abilities, and the tumor growth. HMGA1 gene expression could be efficiently inhibited, and cell proliferation, migration, invasion, and matrix metalloprotease level were also decreased. BALB/C nude mice injected with the MG-63 cells transfected HMGA1 shRNA showed the significant lower tumor weight, tumor volume, and longer tumor-forming time compared with the control group. Our results suggest that knockdown of HMGA1 could inhibit growth and metastasis potentials of MG-63 cells, which may be a therapeutic target protein for osteogenic sarcoma and may be of biological importance.