SMARCA4 germline gene mutation in a patient with epithelial ovarian: A case report

Diagnosis of a SMARCA4-deficient undifferentiated tumor using multigene panel testing: A case report

Key Clinical Message

SMARCA4-deficient thoracic carcinoma is a malignant tumor that may present as cancer of unknown primary. This tumor is refractory and requires a novel approach. In addition to identifying therapeutic targets, multigene panel testing can reveal novel genetic mutations, leading to more pathologically relevant diagnoses and appropriate tumor care.

Abstract

SMARCA4-deficient undifferentiated tumors are characterized by SMARCA4 inactivation. We present a case of a 74-year-old man with an undifferentiated tumor and a novel SMARCA4 mutation detected using multigene panel testing. The tumor was multiagent and refractory to three chemotherapy lines. The test results helped guide appropriate medical management.

Unfolding the rarity of SMARCA4 deficient uterine sarcoma (SDUS): A case report

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SMARCA4 deficient Uterine sarcoma is a rare but highly aggressive sarcoma.

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Diagnostic dilemma is the major hurdle.

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Germline testing warranted to identify hereditary syndrome (RTPS).

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Established chemotherapeutic guidelines for SDUS is sparse.

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Gemcitabine-taxol based regimen yielded significant clinic-radiological benefit.

Background

SMARCA4 deficient uterine sarcoma (SDUS) is a relatively new entity added to the family of uterine sarcoma characterised by SMARCA4/BRG1 deficiency.

Case

A 62 years old lady presented with abdominal pain and vaginal discharge. On evaluation, found to have a pelvic mass with lymph nodal involvement. She underwent hysterectomy with bilateral salpingo-oophorectomy and lymphadenectomy. Preliminary diagnosis made outside was endometrial stromal sarcoma. On further review, had epithelioid and rhabdoid morphology with SMARCA4 loss documented on comprehensive gene profiling. Recurrence within few months of surgery was seen. She was started on gemcitabine and taxol based chemotherapy, showing significant clinical and radiological improvement.

Conclusion

Diagnostic dilemma of this infrequent, aggressive subtype of uterine sarcoma adds to the hindrance in early recognition. Identifying histology surmounted with gene profiling is helpful in establishing diagnosis resulting in early treatment and improving outcomes.

Undifferentiated colonic neoplasm with SMARCA4 germline gene mutation and loss of SMARCA4 protein expression: a case report and literature review

Background

Nonsense mutation or inactivation of SMARCA4 (BRG1) is associated with a monomorphic undifferentiated histological appearance in tumors at different sites. The association between SMARCA4 alteration and undifferentiated colonic carcinoma needs to be further elucidated.

Methods

A 61-year-old male patient presented to the hospital with intermittent epigastric pain in the right upper abdomen and abdominal distension. The enhanced computed tomography detected a mass in the hepatic flexure of the colon and multiple liver metastases.

Results

The right hemicolectomy contained a 4.5-cm undifferentiated malignancy with cells arranged in sheets, abundant necrosis, and areas showing rhabdoid morphology. The immunohistochemistry result showed that these tumor cells were focally positive for cytokeratin (CK), CK8, and CK18; however, diffusely positive for vimentin, P53, Fli-1, and SALL-4. Notably, tumor cells showed a heterogeneous loss of SMARCA4 expression pattern and intact SMARCB1 expression. Next-generation sequencing showed a germline SMARCA4 c.3277C>T(p.R1093*)mutation, somatic APC mutation, and no abnormal SMARCB1 gene. The tumor exhibited microsatellite stability, negative PD-L1 expression, and few infiltrating CD8 + T cells. The patient died a month later after surgery.

Conclusions

We presented a rare case of undifferentiated colonic neoplasm with loss of SMARCA4 protein expression and germline SMARCA4 mutation. Moreover, the role of SMARCA4 alterations in tumor diagnosis and treatment was also summarized.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13000-021-01091-6.

SWI/SNF inactivation in the endometrial epithelium leads to loss of epithelial integrity

Although ARID1A mutations are a hallmark feature, mutations in other SWI/SNF (SWItch/Sucrose Non-Fermentable) chromatin remodeling subunits are also observed in endometrial neoplasms. Here, we interrogated the roles of Brahma/SWI2-related gene 1 (BRG1, SMARCA4), the SWI/SNF catalytic subunit, in the endometrial epithelium. BRG1 loss affects more than one-third of all active genes and highly overlaps with the ARID1A gene regulatory network. Chromatin immunoprecipitation studies revealed widespread subunit-specific differences in transcriptional regulation, as BRG1 promoter interactions are associated with gene activation, while ARID1A binding is associated with gene repression. However, we identified a physiologically relevant subset of BRG1 and ARID1A co-regulated epithelial identity genes. Mice were genetically engineered to inactivate BRG1 specifically in the endometrial epithelium. Endometrial glands were observed embedded in uterine myometrium, indicating adenomyosis-like phenotypes. Molecular similarities were observed between BRG1 and ARID1A mutant endometrial cells in vivo, including loss of epithelial cell adhesion and junction genes. Collectively, these studies illustrate overlapping contributions of multiple SWI/SNF subunit mutations in the translocation of endometrium to distal sites, with loss of cell integrity being a common feature in SWI/SNF mutant endometrial epithelia.

Small-Cell Carcinoma of the Ovary, Hypercalcemic Type-Genetics, New Treatment Targets, and Current Management Guidelines

Small-cell carcinoma of the ovary, hypercalcemic type (SCCOHT) is a rare and highly aggressive ovarian malignancy. In almost all cases, it is associated with somatic and often germline pathogenic variants in SMARCA4, which encodes for the SMARCA4 protein (BRG1), a subunit of the SWI/SNF chromatin remodeling complex. Approximately 20% of human cancers possess pathogenic variants in at least one SWI/SNF subunit. Because of their role in regulating many important cellular processes including transcriptional control, DNA repair, differentiation, cell division, and DNA replication, SWI/SNF complexes with mutant subunits are thought to contribute to cancer initiation and progression. Fewer than 500 cases of SCCOHT have been reported in the literature and approximately 60% are associated with hypercalcemia. SCCOHT primarily affects females under 40 years of age who usually present with symptoms related to a pelvic mass. SCCOHT is an aggressive cancer, with long-term survival rates of 30% in early-stage cases. Although various treatment approaches have been proposed, there is no consensus on surveillance and therapeutic strategy. An international group of multidisciplinary clinicians and researchers recently formed the International SCCOHT Consortium to evaluate current knowledge and propose consensus surveillance and therapeutic recommendations, with the aim of improving outcomes. Here, we present an overview of the genetics of this cancer, provide updates on new treatment targets, and propose management guidelines for this challenging cancer.

An In-Depth Look at Small Cell Carcinoma of the Ovary, Hypercalcemic Type (SCCOHT): Clinical Implications from Recent Molecular Findings

Small cell carcinoma of the ovary, hypercalcemic type (SCCOHT) is a highly aggressive cancer in young women. The histogenesis remains unclear although a potential origin of germ cells has been suggested recently. The high throughput next generation sequencing techniques have facilitated the identification of inactivating SMARCA4 mutations as the driver of SCCOHT. These findings may greatly impact on the prevention, diagnosis, molecular classification and treatment of SCCOHTs. The SMARCA4 mutations, typically associated with dual loss of BRG1 and BRM expression, are highly sensitive and specific for the diagnosis of SCCOHT. Germline mutations of SMARCA4 support familial SCCOHT with a critical requirement of genetic counseling and possible prophylactic surgery for carriers. SCCOHT, malignant atypical teratoid/rhabdoid tumors, thoracic sarcomas and some undifferentiated carcinomas harbor rhabdoid morphology and mutations in the SMARC genes, generating an emerging molecular classification of SMARC-mutated tumors. A multi-modality treatment approach consisting of surgery and high dose multi-agent chemotherapy in atypical teratoid/rhabdoid tumors may have potential benefits for SCCOHT patients. Preliminary studies have implicated that the inhibitors targeting EZH2 and the receptor tyrosine kinase, and anti-PD-L1 immunotherapy might be potentially effective for SCCOHT patients. These recent advances on molecular genetics, diagnosis and treatment of SCCOHT address the necessity of multiple institutional collaboration work among oncologist, pathologist, genomic scientist, geneticist, molecular biologist, and pharmacologist.

Epigenetic Crosstalk between the Tumor Microenvironment and Ovarian Cancer Cells: A Therapeutic Road Less Traveled

Metastatic dissemination of epithelial ovarian cancer (EOC) predominantly occurs through direct cell shedding from the primary tumor into the intra-abdominal cavity that is filled with malignant ascitic effusions. Facilitated by the fluid flow, cells distribute throughout the cavity, broadly seed and invade through peritoneal lining, and resume secondary tumor growth in abdominal and pelvic organs. At all steps of this unique metastatic process, cancer cells exist within a multidimensional tumor microenvironment consisting of intraperitoneally residing cancer-reprogramed fibroblasts, adipose, immune, mesenchymal stem, mesothelial, and vascular cells that exert miscellaneous bioactive molecules into malignant ascites and contribute to EOC progression and metastasis via distinct molecular mechanisms and epigenetic dysregulation. This review outlines basic epigenetic mechanisms, including DNA methylation, histone modifications, chromatin remodeling, and non-coding RNA regulators, and summarizes current knowledge on reciprocal interactions between each participant of the EOC cellular milieu and tumor cells in the context of aberrant epigenetic crosstalk. Promising research directions and potential therapeutic strategies that may encompass epigenetic tailoring as a component of complex EOC treatment are discussed.