A Comparison of Clear Cell Sarcoma to Jaw and Salivary Tumors Bearing EWS Fusions.

OBJECTIVE: To review tumors identified as "clear cell sarcoma" in order to determine similarities to the rare EWS fusion positive jaw and salivary gland tumors clear cell odontogenic carcinoma (CCOC) and clear cell carcinoma of the salivary gland (CCC). METHODS: PubMed was used to collect all reports of clear cell sarcoma (CCS). Search parameters were "clear cell sarcoma" and "CCS." References in the publications were screened and cross-referenced. Data extracted included demographic characteristics, presenting signs and symptoms, radiographic findings, histological and immunohistochemical features and known molecular/genetic aberrations. RESULTS: Clear cell sarcoma has several similarities to CCOC and CCC. All three tumor types have similar histologic appearances including the presence of clear cells, as well as similar genetic profiles in that all harbor an EWSR1-CREB family fusions. Additionally, these tumors appear in soft tissue as well as bone, and can have a prolonged clinical course. CCS can appear anywhere in the body, including the head and neck region. All three tumors appear to have a predilection to women, although CCS may have a slight younger age of onset as compared to CCOC and CCC (3rd vs 5th decade of life, respectively). CONCLUSION: Gaining a better understanding of the similarities and differences between these three tumors may lead to a better understanding of each one.

MYB alternative promoter activity is increased in adenoid cystic carcinoma metastases and is associated with a specific gene expression signature.

OBJECTIVE: Adenoid cystic carcinoma (ACC) is a head and neck cancer with a poor long-term prognosis that shows frequent local recurrences and distant metastases. The tumors are characterized by MYB oncogene activation and are notoriously unresponsive to systemic therapies. The biological underpinnings behind therapy resistance of disseminated ACC are largely unknown. Here, we have studied the molecular and clinical significance of MYB alternative promoter (TSS2) usage in ACC metastases. MATERIALS AND METHODS: MYB TSS2 activity was investigated in primary tumors and metastases from 26 ACC patients using RNA-sequencing and quantitative real-time PCR analysis. Differences in global gene expression between MYB TSS2 high and low cases were studied, and pathway analyses were performed. RESULTS: MYB TSS2 activity was significantly higher in ACC metastases than in primary tumors (median activity 15.1 vs 3.0, P = 0.0003). MYB TSS2 high ACC metastases showed a specific gene expression signature, including increased expression of multi-drug resistance genes and canonical MYB target genes, and suppression of the p53 and NOTCH pathways. CONCLUSIONS: Collectively, our findings indicate that elevated MYB TSS2 activity is associated with metastases, potential drug resistance, and augmented MYB-driven gene expression in ACC. Our study advocates the need for new therapies that specifically target MYB and drug resistance mechanisms in disseminated ACC.

Characterization of a Molecularly Distinct Subset of Oncocytic Pleomorphic Adenomas/Myoepitheliomas Harboring Recurrent ZBTB47-AS1::PLAG1 Gene Fusion.

Recurrent gene fusions are common in salivary gland tumors including benign tumors, such as pleomorphic adenoma (PA) and myoepithelioma (ME). In cases where chromosomal rearrangement is identified in the pleomorphic adenoma gene 1 (PLAG1) gene, different gene partners are found. Oncocytic metaplasia, characterized by oncocytes with abundant eosinophilic granular cytoplasm and hyperchromatic nuclei, is a well-known phenomenon in salivary gland neoplasms. However, the pure oncocytic variant of PA/ME showed PLAG1 gene rearrangements involving various gene partners at the molecular level, without any recurrent fusion being found. Our study includes 20 cases of PA/ME, with 11 females and 9 males. The age of patients ranged from 37 to 96 years, with a median age of 62.8 years. Most tumors originate from the parotid gland. The median size of the tumor was 26.5 mm (range: 13 to 60 mm). Among the 20 cases, 14 were a pure oncocytic variant of PA/ME, whereas 6 cases showed focal oncocytic or oncocytic-like aspects. Molecular studies on 20 cases of PA/ME were conducted. A novel recurrent ZBTB47-AS1::PLAG1 fusion was identified in 6 of 12 cases with pure oncocytic metaplasia, whereas the other cases had PLAG1 gene fusion with different gene partners. The transcriptomic analysis of the cases harboring ZBTB47-AS1::PLAG1 fusion demonstrated that these tumors have a distinct molecular profile from conventional PA/ME. This study reveals a unique subset in the oncocytic PA/ME spectrum characterized by pure oncocytic morphology with larger oncocytic cells and recurrent ZBTB47-AS1::PLAG1 fusion. It also highlights the transcriptomic distinctness of salivary gland adenomas with pure oncocytic metaplasia in the spectrum of salivary gland neoplasms. Further studies are needed to better understand the oncocytic variant of PA/ME and to determine the true nature of oncocytic cells in PA/ME.

Molecular testing in salivary gland cytopathology: A practical overview in conjunction with the Milan system.

Recently, significant advances in the molecular characterization of salivary gland neoplasms have facilitated the classification and diagnosis of specific diagnostic entities. In the highly challenging diagnostic scenario of salivary malignancies, molecular testing is increasingly being adopted in routine practice to refine the cytological diagnosis of salivary lesions. Here, we reviewed the most recent evidence in the field of salivary glands molecular cytopathology.

Pleomorphic Adenoma with a Novel Gene Rearrangement-LINC01606::PLAG1.

BACKGROUND: Pleomorphic adenoma is a well-known benign salivary gland neoplasm characterized by the presence of varying proportions of three different components, including bi-layered ducts, myoepithelial cells, and admixed within a chondromyxoid/fibrous stroma. METHOD: We report an interesting case of an adult male who presented with bleeding from an extensively degenerated parotid gland mass, concerning for a vascular neoplasm versus primary malignant tumor. Microscopically, majority of the viable tumor exhibited diffuse proliferation of spindle to epithelioid cells, with focal areas depicting cribriform glands, ducts, and scant chondromyxoid stroma. RESULT: Next-generation sequencing (NGS) RNA-based fusion panel analysis identified a gene rearrangement involving the pleomorphic adenoma gene 1 (PLAG1), with a novel, cryptogenic fusion partner known as LINC01606; [LINC01606::PLAG1; inv(8;8)(8q12.1;8q12.1)]. CONCLUSION: To the best of our knowledge, this is the first documented case of a long non-coding RNA (lnc-RNA) serving as a rearrangement partner with the PLAG1 gene. We reviewed the molecular characteristics of this entity and explored the potential role of LINC01606::PLAG1 in the tumorigenesis of pleomorphic adenoma.

Pulmonary salivary gland tumor-hyalinizing clear cell carcinoma: a literature review.

Primary pulmonary hyalinizing clear cell carcinoma (HCCC) is a very rare lung tumor that accounts for less than 0.09% of all primary lung tumors and has no specific epidemiology. The correct diagnosis requires imaging, laboratory, pathological, immunohistochemical, and molecular examination. The most typical feature of pulmonary HCCC is the clear cell component with clear stroma. In addition, the fusion gene EWSR1::ATF1 due to t(12;22)(q13;q12) is essential for the pathological diagnosis of pulmonary HCCC. The main treatment for pulmonary HCCC is surgery. This review focus on the pathological features, immunohistochemical examination, mutation analysis and treatment of pulmonary HCCC.

Salivary gland carcinoma: Towards a more personalised approach.

Salivary Gland carcinomas (SGCs) are rare tumors accounting for less than 1% of all cancers with 21 histologically diverse subtypes. The rarity of the disease presents a challenge for clinicians to conduct large size randomized controlled trials. Surgery and radiotherapy remain the only curative treatment for localized disease, whereas treatments for recurrent and metastatic disease remain more challenging with very disappointing results for chemotherapy. The different histological subtypes harbor various genetic alterations, some pathognomonic with a diagnostic impact for pathologists in confirming a difficult diagnosis and others with therapeutic implications regardless of the histologic subtype. Current international guidelines urge pathologists to identify androgen receptor status, HER-2 expression that could be determined by immunohistochemistry, and TRK status in patients with non-adenoid cystic salivary gland carcinoma that are eligible to initiate a systemic treatment, in order to offer them available targeted therapies or refer them to clinical trials based on their mutational profile. A more advanced molecular profiling by next generation sequencing would offer a larger panel of molecular alterations with possible therapeutic implications such as NOTCH, PI3K, BRAF, MYB, and EGFR. In the following review, we present the most common genetic alterations in SGCs as well as actionable mutations with the latest available data on therapeutic options and upcoming clinical trials.

SOX10-Internal Tandem Duplications and PLAG1 or HMGA2 Fusions Segregate Eccrine-Type and Apocrine-Type Cutaneous Mixed Tumors.

Cutaneous mixed tumors exhibit a wide morphologic diversity and are currently classified into apocrine and eccrine types based on their morphologic differentiation. Some cases of apocrine-type cutaneous mixed tumors (ACMT), namely, hyaline cell-rich apocrine cutaneous mixed tumors (HCR-ACMT) show a prominent or exclusive plasmacytoid myoepithelial component. Although recurrent fusions of PLAG1 have been observed in ACMT, the oncogenic driver of eccrine-type cutaneous mixed tumors (ECMT) is still unknown. The aim of the study was to provide a comprehensive morphologic, immunohistochemical, and molecular characterization of these tumors. Forty-one cases were included in this study: 28 cases of ACMT/HCR-ACMT and 13 cases of ECMT. After morphologic and immunohistochemical characterization, all specimens were analyzed by RNA sequencing. By immunohistochemistry, all cases showed expression of SOX10, but only ACMT/HCR-ACMT showed expression of PLAG1 and HMGA2. RNA sequencing confirmed the presence of recurrent fusion of PLAG1 or HMGA2 in all cases of ACMT/HCR-ACMT, with a perfect correlation with PLAG1/HMGA2 immunohistochemical status, and revealed internal tandem duplications of SOX10 (SOX10-ITD) in all cases of ECMT. Although TRPS1::PLAG1 was the most frequent fusion, HMGA2::WIF1 and HMGA2::NFIB were detected in ACMT cases. Clustering analysis based on gene expression profiling of 110 tumors, including numerous histotypes, showed that ECMT formed a distinct group compared with all other tumors. ACMT, HCR-ACMT, and salivary gland pleomorphic adenoma clustered together, whereas myoepithelioma with fusions of EWSR1, FUS, PBX1, PBX3, POU5F1, and KLF17 formed another cluster. Follow-up showed no evidence of disease in 23 cases across all 3 tumor types. In conclusion, our study demonstrated for the first time SOX10-ITD in ECMT and HMGA2 fusions in ACMT and further refined the prevalence of PLAG1 fusions in ACMT. Clustering analyses revealed the transcriptomic distance between these different tumors, especially in the heterogenous group of myoepitheliomas.

Genomics and tumor microenvironment of breast mucoepidermoid carcinoma based on whole-exome and RNA sequencing.

Mammary mucoepidermoid carcinoma (MEC) is a rare entity. The molecular characteristics of breast MEC have not been fully investigated due to its rarity. We performed a retrospective study among 1000 patients with breast carcinomas and identified four cases of breast MEC. Clinical and demographic data were collected. Immunohistochemistry panels which were used to diagnose salivary gland MEC and breast carcinomas were also performed. MAML2 rearrangements were detected by FISH and fusion partners were identified by RNA sequencing. Whole-exome sequencing (WES) was used to reveal the genomes of these four breast MEC. Then, the biological functions and features of breast MEC were further compared with those of invasive breast carcinomas and salivary gland MEC.According to Ellis and Auclair's methods, these four breast MEC could be classified as low-grade breast MEC. All the patients were alive, and disease-free survival (PFS) ranged from 20 months to 67 months. Among these four breast MEC, two cases were triple-negative, and the other two cases were found to be ER positive, with one also showing HER2 equivocal by immunohistochemical staining, but no amplification in FISH. FISH analysis confirmed the presence of the MAML2 translocation in three of four tumors, and CRTC1-MAML2 fusion was confirmed in two of them by RNA-sequencing. The average coverage size of WES for the tumor mutation burden estimation was 32 Mb. MUC4, RP1L1 and QRICH2 mutations were identified in at least three tumors, and these mutation also existed in breast invasive carcinoma databases (TCGA, Cell 2015; TCGA, Nature 2012). The results showed that there were many genes in breast MEC overlapping with the breast invasive carcinoma databases mentioned above, range from 5 to 63 genes (median:21 genes). Next, we assessed immune cell infiltration levels in these tumors. In all these tumors, M2 macrophages and plasma cell were in the high infiltration group. Our breast MEC showed different results from the salivary gland MEC, whose plasma cells were in the low infiltration group. Overall, we first analyzed the genomics and tumor microenvironment of breast mucoepidermoid carcinoma and proposed our hypothesis that although MECs arising in the breast resemble their salivary gland counterparts phenotypically, our findings indicate that breast MECs probably resemble invasive breast carcinomas at the genetic level and immune cell infiltration levels. More cases and in deep research need to be done to further understand this rare carcinoma.

[Correlation of MYB/NFIB gene fusion with the grade and prognosis of head and neck adenoid cystic carcinoma and the concordance of two detection methods].

Objective: To explore the correlation between MYB/NFIB gene fusion and clinicopathological features such as tumor grade and prognosis of head and neck adenoid cystic carcinoma (ACC), and to assess the concordant rate of fluorescent in situ hybridization (FISH) with MYB and NFIB immunohistochemistry. Methods: FISH detection of MYB/NFIB gene fusion was performed on 48 head and neck ACC cases and 15 non-ACC salivary gland tumors at National Cancer Center/National Clinical Research Center for Cancer/Cancer Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China during April 2014 and January 2020. ACC cases were divided into grade Ⅰ-Ⅱ, grade Ⅲ and high-grade transformation, according to pathological grading criteria. Prognosis, FISH results and other clinicopathological characteristics were analyzed. MYB and NFIB immunohistochemistry was performed on the 48 ACC and 15 non-ACC cases. The diagnostic accuracy of FISH and immunohistochemistry was compared. Results: FISH detected MYB/NFIB gene fusion in 41.7% (20/48) of the ACC. Its positive rate was inversely correlated with higher pathological grades (P=0.036). The higher histological grade was linked to worse progression-free survival (P=0.024), whereas there was no correlation between the status of gene fusion detected by FISH and progression-free survival (P=0.536). FISH didnot detect MYB/NFIB gene fusion in 15 non-ACC salivary gland tumors The specificity of diagnosing ACC is 100% for both FISH detection of gene fusion and immunohistochemical detection of MYB expression. However, the sensitivity for both methods was only about 41.7%, respectively. By combining FISH and MYB immunohistochemistry, the sensitivity for diagnosing ACC was increased to 66.7%. Conclusions: MYB/NFIB gene fusion has a lower detection rate in grade Ⅲ ACC and high-grade transformation ACC. Meanwhile gene fusion status is not correlated with prognosis. The sensitivity for diagnosing ACC can be improved by combining FISH and MYB immunohistochemistry.

A phase 2 study of MK-2206 in patients with incurable adenoid cystic carcinoma (Alliance A091104).

BACKGROUND: Recurrent/metastatic adenoid cystic carcinoma (ACC) is a rare, incurable disease. MYB is a putative oncogenic driver in ACC that is often overexpressed through an MYB-NFIB rearrangement. The authors hypothesized that AKT inhibition with the allosteric inhibitor MK-2206 could decrease MYB expression and induce tumor regression in patients with incurable ACC (ClinicalTrials.gov identifier NCT01604772). METHODS: Patients with progressive, incurable ACC were enrolled and received MK-2206 150 mg weekly; escalation to 200 mg was allowed. The primary end point was confirmed response. Secondary end points were progression-free survival, overall survival, and safety. An exploratory analysis evaluating the effect of MK-2206 on MYB expression was conducted in a subset of patients. RESULTS: Sixteen patients were enrolled, and 14 were evaluable for efficacy. No confirmed responses were observed. Thirteen patients had stable disease, and one had disease progression as their best response. The median progression-free survival was 9.7 months (95% CI, 3.8-11.8 months), and the median overall survival was 18.0 months (95% CI, 11.8-29.9 months). Nine of 16 patients (56%) had at least one grade 3 treatment-related adverse event, and the most common were rash (38%), fatigue (19%), decreased lymphocyte count (13%), and hyperglycemia (13%). Twelve of 14 tumors (86%) had detectable MYB expression by immunohistochemistry, and seven of 14 tumors (50%) had an MYB-NFIB gene rearrangement. Serial biopsies revealed decreased MYB levels with MK-2206 in four of five patients. CONCLUSIONS: MK-2206 failed to induce clinical responses in patients with incurable ACC. AKT inhibition may diminish MYB protein levels, although the effect was highly variable among patients. Novel approaches to target MYB in ACC are needed.

Sialadenoma papilliferum-like intraductal papillary tumour: an emerging entity with intercalated duct differentiation showing MAPK pathway activation in both ductal and myoepithelial cells.

Sialadenoma papilliferum-like intraductal papillary tumour (SP-IPT) is a recently described salivary gland tumour that shows identical morphology to sialadenoma papilliferum (SP) except for the lack of an exophytic papillary component. However, the immunohistochemical phenotypes and molecular profiles of SP-IPT remain unclear. This study aims to report new cases of SP-IPT and to determine its cellular differentiation and molecular basis. After histopathological review, four cases of SP-IPT were retrieved. Immunohistochemical staining was performed to analyse the expression patterns of cytokeratin 7 (CK7), p63, smooth muscle actin (SMA), vimentin, S100, mammaglobin, androgen receptor, SOX10, BRAF V600E-mutated protein, and phosphorylated ERK. Sanger sequencing was performed to determine the mutation status of the BRAF, KRAS, NRAS, and HRAS genes. All four cases affected the posterior mandible with a mean age of 62 years and a male-to-female ratio of 3:1. Histologically, all cases consisted of multiple tubular and cystic structures with varying sizes and shapes. The tubulocystic components were lined by a double or few-layered epithelium frequently showing a micropapillary pattern. The outer layer consisted of a rim of myoepithelial cells, which were CK7+/p63+/SMA+/vimentin+/S100+/SOX10+. The inner ductal cells were CK7+/S100+/SOX10+, consistent with intercalated duct differentiation. All cases harboured BRAF V600E mutations, but no other mutations were detected. The BRAF V600E-mutated protein and phosphorylated ERK were expressed in both ductal and myoepithelial cells. These findings demonstrate the immunohistochemical and molecular similarities between SP-IPT and SP and the role and extent of MAPK pathway activation in the pathogenesis of SP-IPT.

Silencing geranylgeranyltransferase I inhibits the migration and invasion of salivary adenoid cystic carcinoma through RhoA/ROCK1/MLC signaling and suppresses proliferation through cell cycle regulation.

Geranylgeranyltransferase type I (GGTase-I) significantly affects Rho proteins, such that the malignant progression of several cancers may be induced. Nevertheless, the effect and underlying mechanism of GGTase-I in the malignant progression of salivary adenoid cystic carcinoma (SACC) remain unclear. This study primarily aimed to investigate the role and mechanism of GGTase-I in mediating the malignant progression of SACC. The level of GGTase-I gene in cells was stably knocked down by short hairpin RNA-EGFP-lentivirus. The effects of GGTase-I silencing on the migration, invasion, and spread of cells were examined, the messenger RNA levels of GGTase-I and RhoA genes of SACC cells after GGTase-I knockdown were determined, and the protein levels of RhoA and RhoA membrane of SACC cells were analyzed. Moreover, the potential underlying mechanism of silencing GGTase-I on the above-mentioned aspects in SACC cells was assessed by examining the protein expression of ROCK1, MLC, p-MLC, E-cadherin, Vimentin, MMP2, and MMP9. Furthermore, the underlying mechanism of SACC cells proliferation was investigated through the analysis of the expression of cyclinD1, MYC, E2F1, and p21CIP1/WAF1 . Besides, the change of RhoA level in SACC tissues compared with normal paracancer tissues was demonstrated through quantitative reverse-transcription polymerase chain reaction and western blot experiments. Next, the effect after GGTase-I silencing was assessed through the subcutaneous tumorigenicity assay. As indicated by the result of this study, the silencing of GGTase-I significantly reduced the malignant progression of tumors in vivo while decreasing the migration, invasion, and proliferation of SACC cells and RhoA membrane, Vimentin, ROCK1, p-MLC, MMP2, MMP9, MYC, E2F1, and CyclinD1 expression. However, the protein expression of E-cadherin and p21CIP1/WAF1 was notably upregulated. Subsequently, no significant transform of RhoA and MLC proteins was identified. Furthermore, RhoA expression in SACC tissues was significantly higher than that in paracancerous tissues. As revealed by the results of this study, GGTase-I shows a correlation with the proliferation of SACC through the regulation of cell cycle and may take on vital significance in the migration and invasion of SACC by regulating RhoA/ROCK1/MLC signaling pathway. GGTase-I is expected to serve as a novel exploration site of SACC.

Defining the relationship of salivary gland malignancies to novel cell subpopulations in human salivary glands using single nucleus RNA-sequencing.

Salivary glands have essential roles in maintaining oral health, mastication, taste and speech, by secreting saliva. Salivary glands are composed of several types of cells, and each cell type is predicted to be involved in the carcinogenesis of different types of cancers including adenoid cystic carcinoma (ACC), acinic cell carcinoma (AciCC), salivary duct carcinoma (SDC), myoepithelial carcinoma (MECA) and other histology. In our study, we performed single nucleus RNA-seq on three human salivary gland samples to clarify the gene expression profile of each complex cellular component of the salivary glands and related these expression patterns to expression found in salivary gland cancers (SGC) to infer cell of origin. By single nucleus RNA-seq, salivary gland cells were stratified into four clusters: acinar cells, ductal cells 1, ductal cells 2 and myoepithelial cells/stromal cells. The localization of each cell group was verified by IHC of each cluster marker gene, and one group of ductal cells was found to represent intercalated ductal cells labeled with HES1. Furthermore, in comparison with SGC RNA-seq data, acinar cell markers were upregulated in AciCC, but downregulated in ACC and ductal cell markers were upregulated in SDC but downregulated in MECA, suggesting that markers of origin are highly expressed in some SGC. Cell type expressions in specific SGC histology are similar to those found in normal salivary gland populations, indicating a potential etiologic relationship.

Cell-type-specific tumour sensitivity identified with a bromodomain targeting PROTAC in adenoid cystic carcinoma.

Salivary gland adenoid cystic carcinoma (ACC) is a rare malignancy with limited treatment options. The development of novel therapies is hindered by a lack of preclinical models. We have generated ACC patient-derived xenograft (PDX) lines that retain the physical and genetic properties of the original tumours, including the presence of the common MYB::NFIB or MYBL1::NFIB translocations. We have developed the conditions for the generation of both 2D and 3D tumour organoid patient-derived ACC models that retain MYB expression and can be used for drug studies. Using these models, we show in vitro and in vivo sensitivity of ACC cells to the bromodomain degrader, dBET6. Molecular studies show a decrease in BRD4 and MYB protein levels and target gene expression with treatment. The most prominent effect of dBET6 on tumours in vivo was a change in the relative composition of ACC cell types expressing either myoepithelial or ductal markers. We show that dBET6 inhibits the progenitor function of ACC cells, particularly in the myoepithelial marker-expressing population, revealing a cell-type-specific sensitivity. These studies uncover a novel mechanistic effect of bromodomain inhibitors on tumours and highlight the need to impact both cell-type populations for more effective treatments in ACC patients. © 2023 The Authors. The Journal of Pathology published by John Wiley & Sons Ltd on behalf of The Pathological Society of Great Britain and Ireland.

Secretory Carcinoma with ETV6-NTRK3 Gene Fusion and Lymph Node Metastasis in Maxillary Gingiva: A Case Report with Pathological and Molecular Correlative Studies.

Secretory carcinoma (SC), also known as mammary analogue secretory carcinoma (MASC), is a rare salivary gland neoplasm with distinctive morphology that harbors a diagnostic ETV6 gene rearrangement. MASC was first described as a type of salivary gland neoplasm in 2010 and resembles breast secretory carcinoma. It is often mistaken for other neoplasms. It usually acts as an indolent tumor but can occasionally behave in an aggressive manner. We present a rare case of a patient with an aggressive SC/MASC of maxillary gingivobuccal sulcus with microcystic, solid and papillary patterns that showed ETV6 gene rearrangement by fluorescence in situ hybridization. Next-generation sequencing revealed t(12;15)(p13;q25) ETV6-NTRK3 translocation. Because SC/MASCs harbor the ETV6-NTRK3 translocation, molecular studies and immunostains are crucial to confirm the diagnosis and direct therapy.

Induction of perineural invasion in salivary adenoid cystic carcinoma by circular RNA RNF111

Objective Local recurrence, distant metastasis, and perineural invasion (PNI) viciously occur in salivary adenoid cystic carcinoma (SACC), resulting in a poor prognosis. This study aimed to explore the mechanism by which circular RNA RNF111 (circ-RNF111) regulates PNI in SACC by targeting the miR-361-5p/high mobility group box 2 (HMGB2) axis. Method Circ-RNF111 and HMGB2 were highly expressed in SACC specimens, while miR-361-5p was underexpressed. Functional experiments showed that ablating circ-RNF111 or promoting miR-361-5p hindered the biological functions and PNI of SACC-LM cells. Results HMGB2 overexpression induced the reversal of SACC-LM cell biological functions and PNI caused by circ-RNF111 knockout. Furthermore, reduction of circ-RNF111 suppressed PNI in a SACC xenograft model. Circ-RNF111 regulated HMGB2 expression through targeted modulation of miR-361-5p. Conclusion Taken together, circ-RNF111 stimulates PNI in SACC by miR-361-5p/HMGB2 axis and may serve as a potential therapeutic target for SACC (AU)

Extracting Potential New Targets for Treatment of Adenoid Cystic Carcinoma using Bioinformatic Methods.

Background: Adenoid cystic carcinoma is a slow-growing malignancy that most often occurs in the salivary glands. Currently, no FDA-approved therapeutic target or diagnostic biomarker has been identified for this cancer. The aim of this study was to find new therapeutic and diagnostic targets using bioinformatics methods. Methods: We extracted the gene expression information from two GEO datasets (including GSE59701 and GSE88804). Different expression genes between adenoid cystic carcinoma (ACC) and normal samples were extracted using R software. The biochemical pathways involved in ACC were obtained by using the Enrichr database. PPI network was drawn by STRING, and important genes were extracted by Cytoscape. Real-time PCR and immunohistochemistry were used for biomarker verification. Results: After analyzing the PPI network, 20 hub genes were introduced to have potential as diagnostic and therapeutic targets. Among these genes, PLCG1 was presented as new biomarker in ACC. Furthermore, by studying the function of the hub genes in the enriched biochemical pathways, we found that insulin-like growth factor type 1 receptor and PPARG pathways most likely play a critical role in tumorigenesis and drug resistance in ACC and have a high potential for selection as therapeutic targets in future studies. Conclusion: In this study, we achieved the recognition of the pathways involving in ACC pathogenesis and also found potential targets for treatment and diagnosis of ACC. Further experimental studies are required to confirm the results of this study.