Detection and screening of chromosomal rearrangements in uterine leiomyomas by long-distance inverse PCR

Sarcomas With RAD51B Fusions Are Associated With a Heterogeneous Phenotype

RAD51B-rearranged sarcomas are rare neoplasms that exhibit a heterogeneous morphology. To date, 6 cases have been reported, all involving the uterus, including 4 perivascular epithelioid cell tumors (PEComas) and 2 leiomyosarcomas (LMS). In this study, we describe the morphologic, immunohistochemical, and molecular features of 8 additional sarcomas with RAD51B rearrangement, including the first extrauterine example. All patients were women with a median age of 57 years at presentation. Seven tumors originated in the uterus, and one in the lower extremity soft tissue, with a median tumor size of 12 cm. Histologically, 4 tumors showed predominantly spindle cell morphology with eosinophilic fibrillary cytoplasm, with or without nuclear pleomorphism, whereas 2 tumors exhibited pleomorphic epithelioid cells, featuring clear to eosinophilic, granular cytoplasm. Two neoplasms exhibited undifferentiated cytomorphology, including one with uniform small blue round cells. All tumors showed high-grade cytologic atypia and high mitotic activity (median: 30/10 high-power fields), whereas coagulative necrosis was noted in 6 cases and lymphovascular invasion in 2. By immunohistochemistry, 2 showed myoid and melanocytic markers in keeping with PEComa, whereas 4 cases were only positive for smooth muscle markers consistent with LMS (including 3 myxoid). The remaining 2 cases had a nonspecific immunoprofile. Five cases tested by targeted RNA sequencing (Archer FusionPlex, Illumina TruSight) showed different fusion partners (HMGA2, PDDC1, and CEP170). RAD51B rearrangements were identified by FISH in the remaining 3 cases. Targeted DNA sequencing in 2 cases was negative for TSC gene alterations. Clinical outcome, available in 5 patients (median follow-up, 19 months), revealed 3 local recurrences, 2 lung metastases, and 4 deaths due to disease. Our results expand the spectrum of sarcomas with RAD51B fusions, demonstrating variable clinical presentations, morphologic spectrum, and fusion partners. These tumors have a predilection for a uterine location, with either LMS, PEComa, or undifferentiated phenotypes, and are associated with an aggressive clinical course.

Novel Approaches to Possible Targeted Therapies and Prophylaxis of Uterine Fibroids

Uterine leiomyomas are the most common benign tumors in women of childbearing age. They may lead to problems of conception or complications during the gestational period. The methods of treatment include surgical (myomectomy and hysterectomy, embolization of arteries) and therapeutic treatment (ulipristal acetate, leuprolide acetate, cetrorelix, goserelin, mifepristone). Both approaches are efficient but incompatible with pregnancy planning. Therefore, there is a call for medical practice to develop therapeutical means of preventing leiomyoma onset in patients planning on becoming pregnant. Based on the analysis of GWAS data on the search for mononucleotide polymorphisms associated with the risk of leiomyoma, in meta-transcriptomic and meta-methylomic studies, target proteins have been proposed. Prospective therapeutic treatments of leiomyoma may be based on chemical compounds, humanized recombinant antibodies, vaccines based on markers of the uterine leiomyoma cells that are absent in the adult organism, or DNA and RNA preparations. Three different nosological forms of the disease associated with driver mutations in the MED12, HMGA2, and FH genes should be considered when developing or prescribing drugs. For example, synthetic inhibitors and vaccines based on matrix metalloproteinases MMP11 and MMP16 are expected to be effective only for the prevention of the occurrence of MED12-dependent nodules.

A View on Uterine Leiomyoma Genesis through the Prism of Genetic, Epigenetic and Cellular Heterogeneity

Uterine leiomyomas (ULs), frequent benign tumours of the female reproductive tract, are associated with a range of symptoms and significant morbidity. Despite extensive research, there is no consensus on essential points of UL initiation and development. The main reason for this is a pronounced inter- and intratumoral heterogeneity resulting from diverse and complicated mechanisms underlying UL pathobiology. In this review, we comprehensively analyse risk and protective factors for UL development, UL cellular composition, hormonal and paracrine signalling, epigenetic regulation and genetic abnormalities. We conclude the need to carefully update the concept of UL genesis in light of the current data. Staying within the framework of the existing hypotheses, we introduce a possible timeline for UL development and the associated key events—from potential prerequisites to the beginning of UL formation and the onset of driver and passenger changes.

Uterine PEComas: A Morphologic, Immunohistochemical, and Molecular Analysis of 32 Tumors

Uterine perivascular epithelioid cell tumors (PEComas) are rare neoplasms that may show overlapping morphology and immunohistochemistry with uterine smooth muscle tumors. In this study, we evaluated the morphologic, immunohistochemical, and molecular features of 32 PEComas, including 11 with aggressive behavior. Two distinct morphologies were observed: classic (n=30) and those with a lymphangioleiomyomatosis appearance (n=2). In the former, patients ranged from 32 to 77 (mean: 51) years and 13% had tuberous sclerosis. Tumors ranged from 0.2 to 17 (mean: 5.5) cm with 77% arising in the corpus. Epithelioid cells were present in 100% and a spindled component was seen in 37%. Nuclear atypia was low (53%), intermediate (17%), or high (30%). Mitoses ranged from 0 to 36 (mean: 6) and 0 to 133 (mean: 19) per 10 and 50 high-power fields, with atypical mitoses present in 30%. Thin and delicate vessels were noted in 100%, clear/eosinophilic and granular cytoplasm in 93%, stromal hyalinization in 73%, necrosis in 30%, and lymphovascular invasion in 10%. All tumors were positive for HMB-45, cathepsin K, and at least one muscle marker, with most expressing melan-A (77%) and/or MiTF (79%). A PSF-TFE3 fusion was identified in one while another showed a RAD51B-OPHN1 fusion. Follow-up ranged from 2 to 175 (mean: 41) months, with 63% of patients alive and well, 20% dead of disease, 13% alive with disease, and 3% dead from other causes. In the latter group (n=2), patients were 39 and 49 years old, one had tuberous sclerosis, while the other had pulmonary lymphangioleiomyomatosis. Both tumors expressed HMB-45, cathepsin K, and muscle markers, but lacked TFE3 and RAD51B rearrangements. The 2 patients are currently alive and well. Application of gynecologic-specific criteria (≥4 features required for malignancy: size ≥5 cm, high-grade atypia, mitoses >1/50 high-power fields, necrosis, and lymphovascular invasion) for predicting outcome misclassified 36% (4/11) of aggressive tumors; thus, a modified algorithm with a threshold of 3 of these features is recommended to classify a PEComa as malignant.

Detection of subclonal L1 transductions in colorectal cancer by long-distance inverse-PCR and Nanopore sequencing

Long interspersed nuclear elements-1 (L1s) are a large family of retrotransposons. Retrotransposons are repetitive sequences that are capable of autonomous mobility via a copy-and-paste mechanism. In most copy events, only the L1 sequence is inserted, however, they can also mobilize the flanking non-repetitive region by a process known as 3' transduction. L1 insertions can contribute to genome plasticity and cause potentially tumorigenic genomic instability. However, detecting the activity of a particular source L1 and identifying new insertions stemming from it is a challenging task with current methodological approaches. We developed a long-distance inverse PCR (LDI-PCR) based approach to monitor the mobility of active L1 elements based on their 3' transduction activity. LDI-PCR requires no prior knowledge of the insertion target region. By applying LDI-PCR in conjunction with Nanopore sequencing (Oxford Nanopore Technologies) on one L1 reported to be particularly active in human cancer genomes, we detected 14 out of 15 3' transductions previously identified by whole genome sequencing in two different colorectal tumour samples. In addition we discovered 25 novel highly subclonal insertions. Furthermore, the long sequencing reads produced by LDI-PCR/Nanopore sequencing enabled the identification of both the 5' and 3' junctions and revealed detailed insertion sequence information.

Riemerella anatipestifer M949_1360 Gene Functions on the Lipopolysaccharide Biosynthesis and Bacterial Virulence

Riemerella anatipestifer causes septicemic and exudative diseases in poultry, resulting in major economic losses to the duck industry. Lipopolysaccharide (LPS), as an important virulence factor in Gram-negative bacteria, can be recognized by the immune system and plays a crucial role in many interactions between bacteria and animal hosts. In this study, we screened out one LPS defective mutant strain RAΔ604 from a random transposon mutant library of R. anatipestifer serotype 1 strain CH3, which did not react with the anti-CH3 LPS monoclonal antibody 1C1 in an indirect enzyme-linked immunosorbent assay. Southern blot analysis confirmed that the genome of RAΔ604 contained a single Tn4351 insert. Then, we found that the M949_1360 gene was inactivated by insertion of the transposon. Using silver staining and western blot analyses, we found that the LPS pattern of RAΔ604 was defective, as compared with that of the wild-type (WT) strain CH3. The mutant strain RAΔ604 showed no significant influence on bacterial growth, while bacterial counting and Live/dead BacLight Bacterial Viability staining revealed that bacterial viability was decreased, as compared with the WT strain CH3. In addition, the abilities of the mutant strain RAΔ604 to adhere and invade Vero cells were significantly decreased. Animal studies revealed that the virulence of the mutant strain RAΔ604 was decreased by more than 200-fold in a duck infection model, as compared with the WT strain CH3. Furthermore, immunization with live bacteria of the mutant strain RAΔ604 protected 87.5% ducks from challenge with R. anatipestifer serotype 1 strain WJ4, indicating that the mutant strain RAΔ604 could be used as a potential vaccine candidate in the future.