Neural crest transcription factor Sox10 is preferentially expressed in triple-negative and metaplastic breast carcinomas

The diagnostic significance of immunohistochemical expression of SOX10 and TRPS1 in triple negative breast cancer

Triple negative breast cancer (TNBC) usually exhibits heterogeneous morphological features. The absence of a specific targeted marker for the breast origin of TNBC makes the diagnosis of metastatic TNBC challenging. TRPS1 is regarded as a diagnostic marker for breast cancer of various subtypes, including the basal type of TNBC. SOX10 has been recorded in to be highly expressed in TNBCs. Our cohort study aimed to: first, assess the diagnostic value of TRPS1 and SOX10 immunohistochemical (IHC) expression in TNBC; second, investigate if any of these two markers are related to the established pathological factors of prognostic significance. The study cohort comprised 84 TNBC cases subjected to TRPS1 and SOX10 IHC staining. TRPS1 expression was demonstrated in 86.9 % of the cases. It was expressed in 85.9 %, 83.3 %, and 100 % of invasive breast carcinoma-no special type (IBC-NST), metaplastic carcinomas, and IBC with medullary pattern, respectively. SOX10 expression was identified in 61.9 % of the cases. Most (85.7 %) of IBC with medullary pattern and 83.3 % of metaplastic carcinomas showed positive SOX10 expression. Evaluation of the combined expression of both markers revealed that 52.4 %, 34.5 %, 9.5 %, and 3.6 % of TNBC cases were SOX10+/TRPS1+, SOX10-/TRPS1+, SOX10+/TRPS1-, and SOX10-/TRPS1-, respectively. TRPS1 and SOX10 are fairly sensitive markers for the diagnosis of TNBC. Accordingly, they may be of help in the detection of metastatic TNBC. However, additional studies are required to evaluate these markers on non-breast tumor tissue to further investigate their specificity.

Diagnostic Approach to Mesenchymal and Spindle Cell Tumors of the Breast

Mesenchymal and spindle cell tumors of the breast represent a broad and heterogeneous group of lesions that may be sampled on core needle biopsy or surgical excision. Mesenchymal lesions unique to the breast are those that derive from the specialized breast myofibroblast, such as mammary myofibroblastoma and pseudoangiomatous stromal hyperplasia. However, any mesenchymal lesion arising in extramammary soft tissue may also arise in the breast, including fibroblastic, peripheral nerve sheath, adipocytic, and vascular lesions. The spindle cell lesions pose the greatest diagnostic challenge, due to the significant radiographic, morphologic, and immunophenotypic overlap within the category of mesenchymal lesions and more broadly with other nonmesenchymal breast lesions. The distinction is particularly challenging on the limited material of breast core needle biopsies, and caution should be taken before definitively classifying a breast spindle cell lesion on core needle biopsy to avoid unnecessary treatment if misdiagnosed. Consideration of a wide differential diagnosis, adequate sampling of a resection specimen, use of a targeted immunopanel, and selective use of molecular assays are essential steps for accurate classification of mesenchymal lesions in the breast. This review covers the clinical, histologic, and immunophenotypic features of mesenchymal tumors of the breast, with a special emphasis on the differential diagnoses unique to the breast and challenges encountered on breast core needle biopsy.

Utility of Wnt family member 9b (Wnt9b) immunohistochemistry in the cytologic diagnosis of metastatic breast carcinoma

Wnt family member 9b (Wnt9b) has been demonstrated as a valuable marker for breast cancer diagnosis in surgical pathology. In this study, we examined the utility of Wnt9b in diagnosing metastatic breast carcinoma in cytology samples. Cell blocks from fine needle aspirations (FNA) and fluid specimens of 96 metastatic breast carcinomas and 123 primary and metastatic non-breast neoplasms from various organ systems were evaluated by Wnt9b and GATA3 immunohistochemistry (IHC). Wnt9b and GATA3 were positive in 81.3% and 92.7% of metastatic breast carcinomas, respectively. Conversely, 93.5% and 90.0% of non-breast, non-urothelial carcinomas were negative for Wnt9b and GATA3, respectively. Wnt9b expression was positive in rare gastrointestinal, gynecological, lung, pancreas, and salivary gland tumors. All twenty-eight urothelial carcinomas were negative for Wnt9b, while twenty-six (92.9%) were positive for GATA3. Wnt9b was slightly less sensitive but more specific than GATA3 in diagnosing metastatic breast cancer in cytology samples. Particularly, Wnt9b shows higher specificity in differentiating breast and urothelial primaries. The combined use of Wnt9b and GATA3 may increase diagnostic accuracy.

Single-cell chromatin accessibility reveals malignant regulatory programs in primary human cancers

To identify cancer-associated gene regulatory changes, we generated single-cell chromatin accessibility landscapes across eight tumor types as part of The Cancer Genome Atlas. Tumor chromatin accessibility is strongly influenced by copy number alterations that can be used to identify subclones, yet underlying cis-regulatory landscapes retain cancer type-specific features. Using organ-matched healthy tissues, we identified the "nearest healthy" cell types in diverse cancers, demonstrating that the chromatin signature of basal-like-subtype breast cancer is most similar to secretory-type luminal epithelial cells. Neural network models trained to learn regulatory programs in cancer revealed enrichment of model-prioritized somatic noncoding mutations near cancer-associated genes, suggesting that dispersed, nonrecurrent, noncoding mutations in cancer are functional. Overall, these data and interpretable gene regulatory models for cancer and healthy tissue provide a framework for understanding cancer-specific gene regulation.

TRPS1 expression in MPNST is correlated with PRC2 inactivation and loss of H3K27me3

Initially described as a highly specific immunohistochemical marker for carcinomas of mammary origin, trichorhinophalangeal syndrome type 1 (TRPS1) has subsequently been detected in a variety of other non-mammary tumors. In this study, we examined the immunohistochemical expression of TRPS1 in 114 peripheral nerve sheath tumors, including 43 malignant peripheral nerve sheath tumors (MPNSTs), 58 schwannomas, including 9 cellular neurofibromas, and 13 neurofibromas, including 1 atypical neurofibroma. Notably, TRPS1 was expressed in 49% of MPNSTs and was absent in all schwannomas and neurofibromas. All MPNSTs showed TRPS1 labeling in >50% of nuclei, with 95% of cases demonstrating diffuse labeling. Most cases (67%) showed weak TRPS1 immunoreactivity, while a smaller subset showed moderate (24%) or strong (9%) intensity staining. Analysis of publicly available gene expression datasets revealed higher levels of TRPS1 mRNA in MPNSTs with PRC2 inactivation. In keeping with this finding, TRPS1 expression was more commonly observed in MPNSTs with loss of H3K27me3, suggesting a potential relationship between TRPS1 and the PRC2 complex. This study further broadens the spectrum of TRPS1-expressing tumors to include MPNST.

Metastatic triple-negative breast carcinoma mimicking melanoma: A potential diagnostic pitfall

Melanoma, with its diverse histopathologic characteristics, can mimic both benign nevi and neoplasms of various cell lineages. Immunohistochemistry (IHC) can play a vital role in melanoma diagnosis, particularly when the cell lineage is unclear on hematoxylin and eosin sections. Commonly utilized IHC stains for melanoma diagnosis include SOX10, Melan-A, and S100. A relatively novel stain, PReferentially expressed Antigen in MElanoma (PRAME), is also proving useful in accurate melanoma diagnosis. However, none of these stains are completely specific to melanocytes or melanoma, and misinterpretation can lead to incorrect diagnoses. This report presents a unique case of triple-negative breast carcinoma (TNBC) metastatic to the skin exhibiting histopathologic characteristics similar to melanoma, including positivity for SOX10 and PRAME. Our aim is to highlight TNBC metastatic to the skin as a potential diagnostic pitfall.

Metastatic Neoplasms to the Breast

OBJECTIVE

When the clinical presentation is related to the metastatic mass and a radiologically solitary tumor focus is detected, especially in cases where clinical information is not taken into account or is insufficient, if a possible metastatic neoplasia is not kept in mind then it is possible to evaluate the tumor as a primary breast neoplasm. In this study, it is aimed to present our cases of non-hematopoietic metastatic neoplasms and to evaluate the clinicopathological features that may aid in distinguishing metastatic from primary neoplasms.

MATERIAL AND METHODS

This study includes cases diagnosed with metastatic non-hematopoietic breast neoplasm in breast resection materials in our center, between the years 2010-2023. All cases were analyzed retrospectively by evaluating clinicopathological features.

RESULTS

Of the 15 subjects included in the study, 11 (73%) were female and 4 (27%) were male. The mean age of the patients were 46.9 ranged from 22 to 63 years. The most frequent metastatic malignancy was carcinoma (60%), followed by melanoma (33%) and sarcoma (7%). Of the 9 patients with metastatic carcinoma, the primary tumor originated from the lungs in 4, from gastrointestinal system in 2, female genital tract in 2, and kidney in 1 patient. Sarcoma diagnosis was given in a single patient and the histology was a leiomyosarcoma originating from kidney.

CONCLUSION

A careful histomorphological and immunohistochemical evaluation and a detailed examination of the clinicoradiological data are critical to establish the right course in patient management, treatment plan and to correctly predict the prognosis.

Breast Cancer Histopathology in the Age of Molecular Oncology

For more than a century, microscopic histology has been the cornerstone for cancer diagnosis, and breast carcinoma is no exception. In recent years, clinical biomarkers, gene expression profiles, and other molecular tests have shown increasing utility for identifying the key biological features that guide prognosis and treatment of breast cancer. Indeed, the most common histologic pattern-invasive ductal carcinoma of no special type-provides relatively little guidance to management beyond triggering grading, biomarker testing, and clinical staging. However, many less common histologic patterns can be recognized by trained pathologists, which in many cases can be linked to characteristic biomarker and gene expression patterns, underlying mutations, prognosis, and therapy. Herein we describe more than a dozen such histomorphologic subtypes (including lobular, metaplastic, salivary analog, and several good prognosis special types of breast cancer) in the context of their molecular and clinical features.

Pigmented Epidermotropic Breast Carcinoma: A Diagnostic Pitfall Mimicking Melanoma A Case Report and Literature Review

We report the clinical and pathologic features of a patient with breast carcinoma, who developed clinically visible pigmented skin lesions during the course of the disease. The combination of clinical pigmentation, histological pagetoid epidermal spread, and considerable melanin pigment within tumour cells lead to a misdiagnosis of melanoma. This case provides a striking example of the ability of epidermotropic breast carcinoma to mimic melanoma. A literature review is also reported.

TRPS1 is a promising marker for all subtypes of breast cancer

AIMS

Trichorhinophalangeal syndrome-1 (TRPS1) has been proposed as a novel breast marker with equally high expression in breast cancer (BC) subtypes, making it a useful diagnostic tool. Here, its expression was evaluated alongside other commonly used markers [GATA3, GCDFP15, mammaglobin (MGB) and SOX10] in a large cohort of BCs (n = 1852) and their corresponding nodal metastases. Its usefulness as a diagnostic tool and its correlation with clinicopathological features were assessed.

METHODS AND RESULTS

TRPS1 was expressed at 75.8% overall in the BC cohort, with at least 58% expression among BC subtypes. It was less sensitive than GATA3 for luminal and HER2-overexpressing (HER2-OE) cancers (luminal A: 82 versus 97%; luminal B: 80 versus 95%; HER2-OE: 62 versus 76%), but it was the most sensitive for TNBC (60 versus ≤ 41%). It showed a stable expression in nodal metastases (primary tumour 76 versus nodal metastasis 78%), unlike a reduced nodal expression for GATA3 (86 versus 77%). TRPS1 outperformed GATA3 in detecting non-luminal cancers when paired with other breast markers. TRPS1 and GCDFP15 was the most sensitive combination in TNBC detection, with a 76% detection rate. For TRPS1-negative and GCDFP15-negative TNBCs, SOX10 was more sensitive than GATA3 (29 versus 24%).

CONCLUSIONS

TRPS1 is a highly sensitive marker for all breast cancer subtypes, outperforming GATA3 in non-luminal cancers and displaying the highest sensitivity for TNBC detection when combined with GCDFP15. It is a valuable addition to the breast marker panel for accurate identification of BC.

Melanocyte colonization and pigmentation of breast carcinoma: A case report

Pigmented mammary Paget disease is a rare variant of mammary Paget disease that is often clinically misdiagnosed as a melanocytic lesion of the skin or nipple-areolar complex. Careful morphological assessment, along with the performance of adequate immunohistochemical stains, will help in achieving the right diagnosis and avoiding misdiagnosis of the entity as malignant melanoma. We report a rare case of pigmented mammary Paget disease with concomitant colonization of the underlying invasive ductal carcinoma by melanocytes mimicking melanoma.

Role of SOX10 Immunohistochemical Expression in Diagnosing Triple Negative Breast Cancer and Its Correlation With Clinicopathological Features

BACKGROUND

Triple-negative breast cancer (TNBC) poses a diagnostic challenge for histopathologists due to the reduced frequency of breast-specific markers. SOX10 has emerged as a useful diagnostic marker for TNBC. The aim of our study was to determine the frequency of SOX-10 immunohistochemical (IHC) expression in our cohort and assess its correlation with clinicopathological and histological features.

MATERIALS AND METHODS

We included 72 primary TNBC cases. Specimens included tru-cut biopsies and excision specimens. We stained whole slide sections of these specimens with SOX10 antibody and calculated its frequency (%) of expression and H-score. We applied the chi-square test to assess the correlation between SOX10 expression and clinicopathological and histological features such as the patient's age, specimen type, tumor size, histological type, histological grade, nuclear pleomorphism, mitotic count, tumor-infiltrating lymphocytes (TILs), necrosis, calcification, lymphovascular invasion (LVI), lymph node involvement, T stage, and N stage.

RESULTS

SOX10 expression was observed in 42 (58.3%) cases with a median H-score of 57.5. The expression was significantly higher in tru-cut biopsy specimens as compared to excision specimens (73.5 vs 41.7%) and TILs negative tumors as compared to TILs positive tumors (64.3% vs 27.3). Metaplastic carcinoma showed reduced expression when compared with non-metaplastic tumors (35.7% vs 63.8%), but statistical significance was not achieved. No correlation was observed with the patient's age, tumor size, histological type, histological grade, nuclear pleomorphism, mitotic count, necrosis, calcification, LVI, lymph node involvement, T stage, and N stage.

CONCLUSION

SOX10 was expressed in more than half of the TNBC cases of our study which not only highlights its diagnostic utility but advocated its application in combination with other breast-specific markers. The expression didn't correlate with the majority of clinicopathological and histological features, but correlation with tru-cut biopsy specimens and absence of TILs draws attention towards possible roles of proper fixation and host immunity, respectively.

Immunohistochemical Characterization of a Large Cohort of Triple Negative Breast Cancer

Introduction. Triple negative breast carcinomas are characterized by a lack of hormone receptor and HER2 expression and inconsistent expression of breast-specific immunohistochemical markers. The expression of many site-specific markers in these tumors is largely unknown. The objective of the study was to examine the expression of widely used immunohistochemical markers on a large cohort of triple negative breast cancer. Methods. Sections from tissue microarrays were stained with 47 markers using routine protocols. Most markers were scored using a modified Allred method. ATRX, BAP1, SMAD4, e-cadherin, and beta-catenin were scored as retained or lost. Mammaglobin was considered positive if there was at least moderate intensity staining in any tumor cells. P16 was scored as overexpressed or not overexpressed; p53 was scored as wildtype, overexpressed, null, or cytoplasmic. Results. The cohort consisted of 639 tumors including 601 primary and 32 metastases. Overall, 96% expressed GATA3, mammaglobin, and/or SOX10 while 97% of no special type tumors expressed this panel. Carcinoma of apocrine differentiation demonstrated an AR positive, SOX10 negative, K5 negative/focal immunophenotype. PAX8 (SP348), WT1, Napsin A, and TTF1 (8G7G3/1) were never or rarely expressed while CA9, CDX2, NKX3.1, SATB2 (SATBA410), synaptophysin, and vimentin were variably expressed. Conclusions. Almost all TNBC express at least 1 of the 3 IHC markers: GATA3, mammaglobin, and/or SOX10. Carcinoma of apocrine differentiation is characterized by an AR positive, SOX10 negative, K5 negative or focal immunophenotype. Cautious interpretation of so-called site-specific markers, with knowledge of antibody clones, is required in excluding the diagnosis of triple negative breast cancer.

Multimodality imaging review of metastatic melanoma involving the breast

Melanoma is among the most commonly reported non-mammary primary tumors to metastasize to the breast. Unfortunately, evidence of melanoma metastasis to any site portends a poor prognosis. Imaging studies can be useful in the early detection of metastatic melanoma which is essential for appropriate management of this disease. There have been very few previous studies on the imaging findings of metastatic melanoma especially across multiple imaging modalities. This review aims to describe these imaging features seen on mammography, ultrasound, magnetic resonance imaging (MRI) and fluorodeoxyglucose-positron emission tomography computed tomography (FDG PET/CT) using three case examples. Our findings, consistent with previous studies, describe melanoma metastases to the breast as largely non-specific, round or oval masses with circumscribed margins and homogeneous internal enhancement.

Carcinoma of unknown primary (CUP): an update for histopathologists

Carcinoma of unknown primary (CUP) is a heterogeneous group of metastatic cancers in which the site of origin is not identifiable. These carcinomas have a poor outcome due to their late presentation with metastatic disease, difficulty in identifying the origin and delay in treatment. The aim of the pathologist is to broadly classify and subtype the cancer and, where possible, to confirm the likely primary site as this information best predicts patient outcome and guides treatment. In this review, we provide histopathologists with diagnostic practice points which contribute to identifying the primary origin in such cases. We present the current clinical evaluation and management from the point of view of the oncologist. We discuss the role of the pathologist in the diagnostic pathway including the control of pre-analytical conditions, assessment of sample adequacy, diagnosis of cancer including diagnostic pitfalls, and evaluation of prognostic and predictive markers. An integrated diagnostic report is ideal in cases of CUP, with results discussed at a forum such as a molecular tumour board and matched with targeted treatment. This highly specialized evolving area ultimately leads to personalized oncology and potentially improved outcomes for patients.

Immunohistochemistry in the Diagnosis and Classification of Breast Tumors

CONTEXT.—

In the clinical practice of breast pathology, immunohistochemistry (IHC) of different markers is widely used for the diagnosis and classification of breast lesions.

OBJECTIVE.—

To provide an overview of currently used and recently identified IHC stains that have been implemented in the field of diagnostic breast pathology.

DATA SOURCES.—

Data were obtained from literature review and clinical experience of the authors as breast pathologists.

CONCLUSIONS.—

In the current review, we summarize the common uses of IHC stains for diagnosing different types of breast lesions, especially invasive and noninvasive breast lesions, and benign and malignant spindle cell lesions. In addition, the cutting-edge knowledge of diagnostic carcinoma markers will lead us to further understand the different types of breast carcinoma and differentiate breast carcinomas from other carcinomas of similar morphology. Knowing the strengths and limitations of these markers is essential to the clinical practice of breast pathology.

Diagnostic Pitfalls in Breast Cancer Pathology With an Emphasis on Core Needle Biopsy Specimens

CONTEXT.—

Breast pathology has many mimics and diagnostic pitfalls. Evaluation of malignant breast lesions, particularly in the biopsy setting, can be especially challenging, with diagnostic errors having significant management implications.

OBJECTIVE.—

To discuss the pitfalls encountered when evaluating ductal carcinoma in situ and invasive breast carcinomas, providing histologic clues and guidance for appropriate use and interpretation of immunohistochemistry to aid in the correct diagnosis.

DATA SOURCES.—

Data were obtained from review of pertinent literature of ductal carcinoma in situ and invasive breast carcinomas and from the experience of the authors as practicing breast pathologists.

CONCLUSIONS.—

Awareness of the pitfalls in diagnosing breast cancers is important when creating a differential diagnosis for each breast lesion evaluated. This review will cover some of these scenarios to aid in the diagnostic process.

TRPS1 expression in cytokeratin 5 expressing triple negative breast cancers, its value as a marker of breast origin

The lack of oestrogen receptor, progesterone receptor and human epidermal growth factor receptor-2 expression in breast cancer (BC) is the basis for the categorization of the tumour as triple negative breast carcinoma (TNBC). The majority of TNBCs are aggressive tumours with common metastases and decreased expression of markers that could help in identifying the metastatic lesion as of mammary origin. Breast markers, such as gross cystic disease fluid protein-15 (GCDPF-15), GATA binding protein 3 (GATA3), mammaglobin (MGB) and SOX10, are not uniquely specific to BC. Our aim was to evaluate trichorhinophalangeal syndrome type 1 (TRPS1) protein as a breast marker in a series of cytokeratin-5-expressing TNBC, mostly corresponding to basal-like TNBCs, previously characterized for the expression of other breast markers. One hundred seventeen TNBCs in tissue microarrays were immunostained for TRPS1. The cut-off for positivity was ≥ 10%. The reproducibility of this classification was also assessed. TRPS1 positivity was detected in 92/117 (79%) cases, and this exceeded the expression of previously tested markers like SOX10 82 (70%), GATA3 11 (9%), MGB 10 (9%) and GCDFP-15 7 (6%). Of the 25 TRPS1-negative cases, 11 were positive with SOX10, whereas 5 to 6 dual negatives displayed positivity for the other makers. The evaluation showed substantial agreement. Of the five markers compared, TRPS1 seems the most sensitive marker for the mammary origin of CK5-expressing TNBCs. Cases that are negative are most often labelled with SOX10, and the remainder may still demonstrate positivity for any of the 3 other markers. TRPS1 has a place in breast marker panels.

Lineage plasticity enables low-ER luminal tumors to evolve and gain basal-like traits

Stratifying breast cancer into specific molecular or histologic subtypes aids in therapeutic decision-making and predicting outcomes; however, these subtypes may not be as distinct as previously thought. Patients with luminal-like, estrogen receptor (ER)-expressing tumors have better prognosis than patients with more aggressive, triple-negative or basal-like tumors. There is, however, a subset of luminal-like tumors that express lower levels of ER, which exhibit more basal-like features. We have found that breast tumors expressing lower levels of ER, traditionally considered to be luminal-like, represent a distinct subset of breast cancer characterized by the emergence of basal-like features. Lineage tracing of low-ER tumors in the MMTV-PyMT mouse mammary tumor model revealed that basal marker-expressing cells arose from normal luminal epithelial cells, suggesting that luminal-to-basal plasticity is responsible for the evolution and emergence of basal-like characteristics. This plasticity allows tumor cells to gain a new lumino-basal phenotype, thus leading to intratumoral lumino-basal heterogeneity. Single-cell RNA sequencing revealed SOX10 as a potential driver for this plasticity, which is known among breast tumors to be almost exclusively expressed in triple-negative breast cancer (TNBC) and was also found to be highly expressed in low-ER tumors. These findings suggest that basal-like tumors may result from the evolutionary progression of luminal tumors with low ER expression.

Pitfalls in breast pathology

Accurate pathological diagnosis is the cornerstone of optimal clinical management for patients with breast disease. As non-operative diagnosis has now become the standard of care, histopathologists encounter the daily challenge of making definitive diagnoses on limited breast core needle biopsy (CNB) material. CNB samples are carefully evaluated using microscopic examination of haematoxylin and eosin (H&E)-stained slides and supportive immunohistochemistry (IHC), providing the necessary information to inform the next steps in the patient care pathway. Some entities may be difficult to distinguish on small tissue samples, and if there is uncertainty a diagnostic excision biopsy should be recommended. This review discusses (1) benign breast lesions that may mimic malignancy, (2) malignant conditions that may be misinterpreted as benign, (3) malignant conditions that may be incorrectly diagnosed as primary breast carcinoma, and (4) some IHC pitfalls. The aim of the review is to raise awareness of potential pitfalls in the interpretation of breast lesions that may lead to underdiagnosis, overdiagnosis, or incorrect classification of malignancy with potential adverse outcomes for individual patients.

The Utility of SOX10 Immunohistochemical Staining in Breast Pathology

OBJECTIVES

SOX10 expression helps identify melanocytic lesions. Over time, novel uses have been identified, such as expression in triple-negative breast cancer (TNBC). We evaluated the usefulness of SOX10 in breast pathology-specifically, identification and subtyping of TNBC and distinction from gynecologic carcinomas, use as a myoepithelial marker, and in the distinction of usual ductal hyperplasia (UDH) from atypical ductal hyperplasia (ADH).

METHODS

Several breast and gynecologic carcinoma tissue microarrays containing a total of 492 cases were stained with SOX10. Whole sections of 34 ADH, 50 UDH, and 29 ductal carcinoma in situ (DCIS) samples were also stained with SOX10.

RESULTS

SOX10 expression was identified in 67% of consecutive TNBC cases. Expression was mostly seen in nonapocrine, androgen receptor (AR)-negative TNBCs. All gynecologic carcinomas (n = 157) were negative. All UDH cases showed mosaic SOX10 expression, while all ADH cases lacked expression. All estrogen receptor (ER)-positive DCIS (n = 19) specimens were negative for SOX10, while 2 of 10 ER-negative DCIS specimens were positive for SOX10. The latter 2 cases showed SOX10-positive invasive carcinomas.

CONCLUSIONS

SOX10 identifies nonluminal AR-type TNBC and is useful in distinguishing TNBC from gynecologic carcinomas. SOX10 can distinguish UDH from ADH. SOX10 is not useful in distinguishing ADH from DCIS.

FOXA1, FOXA2, SOX10 and GAS2 Gene Expression in Oral Squamous Cell Carcinoma and Their Relationship with Clinicopathological Indices

Background: The use of molecular methods in cancer diagnosis has led to a better prognosis. One of the important gene families in the carcinogenic pathways of various cancers is the forkhead box (FOX) family genes. Moreover, developmental transcription factors and proapoptotic proteins play critical roles in cell function and carcinogenesis. Objectives: The current study aimed to evaluate the expression of A1 FOXA1, FOXA2, SOX10, and growth arrest specific 2 (GAS2) genes in oral squamous cell carcinoma (OSCC) tumors due to biomarker discovery and early diagnosis of cancer. Methods: To evaluate the expression of FOXA1, FOXA2, SOX10, and GAS2 genes, 30 OSCC samples and 30 normal specimens were obtained from Imam Khomeini Hospital Cancer Institute. RNA extraction and cDNA synthesis were done by relevant kits. After a specific primer design for FOXA1, FOXA2, SOX10, and GAS2 genes, real-time PCR was done to evaluate the genes’ expression for molecular biomarker discovery and validation. ANOVA and independent t-test were used to analyze the data. Results: Significant differences were observed in the expression of the studied genes in tumor and control tissues (P < 0.001). The results showed that FOXA1, GAS2, and SOX10 expressions in tumor and normal cells have significant differences (P < 0.001). Regardless of FOXA1, FOXA2 and SOX10, there was a significant difference in the expression of GAS2 genes in term patients’ age (P < 0.05) and overexpressed in patients over 55 years. SOX10 gene is upregulated in grade II OSCC tumors but there is no significant difference in expression of FOXA1, FOXA2, and GAS2 in different stages and grades. The ROC curve analysis, FOXA1, and FOXA2 showed AUC = 0.66 and AUC = 0.57 respectively. Meanwhile, SOX10 and GAS2 showed AUC = 0.9 and AUC = 1 respectively. Conclusions: In general, the expression of FOXA1, GAS2, and SOX10 genes in cancer and control tissues were different, and therefore the role of these genes in OSCC is confirmed. Also, in the present study, the biomarker potential of SOX10 and GAS2 genes for OSCC diagnosis was demonstrated. In the current study, the important role of the studied genes in OSCC diagnosis was shown. However, further studies are needed to confirm this.

Epigenome erosion and SOX10 drive neural crest phenotypic mimicry in triple-negative breast cancer

Intratumoral heterogeneity is caused by genomic instability and phenotypic plasticity, but how these features co-evolve remains unclear. SOX10 is a neural crest stem cell (NCSC) specifier and candidate mediator of phenotypic plasticity in cancer. We investigated its relevance in breast cancer by immunophenotyping 21 normal breast and 1860 tumour samples. Nuclear SOX10 was detected in normal mammary luminal progenitor cells, the histogenic origin of most TNBCs. In tumours, nuclear SOX10 was almost exclusive to TNBC, and predicted poorer outcome amongst cross-sectional (p = 0.0015, hazard ratio 2.02, n = 224) and metaplastic (p = 0.04, n = 66) cases. To understand SOX10’s influence over the transcriptome during the transition from normal to malignant states, we performed a systems-level analysis of co-expression data, de-noising the networks with an eigen-decomposition method. This identified a core module in SOX10’s normal mammary epithelial network that becomes rewired to NCSC genes in TNBC. Crucially, this reprogramming was proportional to genome-wide promoter methylation loss, particularly at lineage-specifying CpG-island shores. We propose that the progressive, genome-wide methylation loss in TNBC simulates more primitive epigenome architecture, making cells vulnerable to SOX10-driven reprogramming. This study demonstrates potential utility for SOX10 as a prognostic biomarker in TNBC and provides new insights about developmental phenotypic mimicry—a major contributor to intratumoral heterogeneity.

Clinical-pathologic characteristics and response to neoadjuvant chemotherapy in triple-negative low Ki-67 proliferation (TNLP) breast cancers

Triple-negative breast cancers (TNBCs) often have a high Ki-67 proliferation index and respond favorably to neoadjuvant chemotherapy (NACT) with pathologic complete response (pCR) resulting in ~40% of cases. Nevertheless, morbidity/mortality remain high, mostly due to recurrence in patients with residual disease. In contrast, the incidence and clinical features of TNBC with low proliferation (TNLP), defined as TNBC with a Ki-67 index of ≤30% remains unknown. We report 70 cases of TNLP identified at our center from 2008 to 2018, including 18 treated with NACT. TNLP tumors represent <1% of all breast cancers, and ~5-10% of TNBCs. Ninety percent of carcinomas were grade I/II and 70% were either pure apocrine or showed apocrine differentiation. Fifty cases had available immunohistochemistry results; 80%, 84%, 22%, and 20% were positive for AR, INPP4B, nestin, and SOX10, respectively. With a median follow-up of 72 months, 14% experienced recurrence, and 11% died of breast cancer. The tumor stage was prognostic. Among 39 stage-I patients, 18 (46%) received chemotherapy, but this did not impact survival. There was a trend for improved recurrence-free survival with chemotherapy in stage-II patients. Of the 18 patients treated with NACT, 2 (11%) showed pCR; these were notable for either high stromal TILs or a high mitotic count despite a low Ki-67 index. TNLPs are enriched in low to intermediate-grade carcinomas with apocrine features. Due to overall good prognosis of stage-I TNLP and the lack of clear benefit of chemotherapy, de-escalation of chemotherapy may be considered in select patients with stage-I TNLP.

High-Grade Spindle Cell Lesions of the Breast: Key Pathologic and Clinical Updates

Most of the high-grade spindle cell lesions of the breast are malignant phyllodes tumors (MPTs), spindle cell carcinomas (SpCCs), and matrix-producing metaplastic breast carcinomas (MP-MBCs). MPTs have neoplastic spindle stromal cells and a classic leaf-like architecture with subepithelial stromal condensation. MPTs are often positive for CD34, CD117, and bcl-2 and are associated with MED12, TERT, and RARA mutations. SpCCs and MP-MBCs are high-grade metaplastic carcinomas, whereas neoplastic epithelial cells become spindled or show heterologous mesenchymal differentiation, respectively. The expression of epithelial markers must be evaluated to make a diagnosis. SAS, or rare metastatic spindle cell tumors, are seen in the breast, and clinical history is the best supporting evidence. Surgical resection is the standard of care.

Are Transcription Factors Plausible Oncotargets for Triple Negative Breast Cancers?

Simple Summary

Triple negative breast cancer is a type of breast cancer that does not have a selective and effective therapy. It is known that this cancer possesses high abundance of certain proteins called transcription factors, which are essential for their growth. However, inhibiting transcription factors is very difficult with common therapeutics due to their inaccessibility inside the cell and their molecular structure. In this work, we identified the most important transcription factors for the growth of triple negative breast cancers, and that can predict worse clinical outcome. Moreover, we described different strategies that have been utilised to inhibit them. A successful inhibition of these transcription factors could reduce the mortality and convalescence associated with triple negative breast cancers.

Abstract

Breast cancer (BC) is the most diagnosed cancer worldwide and one of the main causes of cancer deaths. BC is a heterogeneous disease composed of different BC intrinsic subtypes such as triple-negative BC (TNBC), which is one of the most aggressive subtypes and which lacks a targeted therapy. Recent comprehensive analyses across cell types and cancer types have outlined a vast network of protein–protein associations between transcription factors (TFs). Not surprisingly, protein–protein networks central to oncogenesis and disease progression are highly altered during TNBC pathogenesis and are responsible for the activation of oncogenic programs, such as uncontrollable proliferation, epithelial-to-mesenchymal transition (EMT) and stemness. From the therapeutic viewpoint, inhibiting the interactions between TFs represents a very significant challenge, as the contact surfaces of TFs are relatively large and featureless. However, promising tools have emerged to offer a solution to the targeting problem. At the clinical level, some TF possess diagnostic and prognostic value in TNBC. In this review, we outline the recent advances in TFs relevant to TNBC growth and progression. Moreover, we highlight different targeting approaches to inhibit these TFs. Furthermore, the validity of such TFs as clinical biomarkers has been explored. Finally, we discuss how research is likely to evolve in the field.

Combination of GATA3, SOX-10, and PAX8 in a Comprehensive Panel to Diagnose Breast Cancer Metastases

BACKGROUND/AIM

It can be difficult to establish the origin of a tumor in metastatic breast cancer (MBC), especially with triple-negative breast cancer (TNBC) or high-grade features. We evaluated the diagnostic utility of GATA3, SOX10, and PAX8 panels in MBC by comparing their expression in each molecular subtype of MBC.

PATIENTS AND METHODS

We evaluated 84 MBC and 37 primary TNBC cases using GATA3, SOX10, and PAX8 staining in whole tissue sections.

RESULTS

GATA3 was least sensitive in the detection of metastatic TNBC (metastatic non-TNBC, 0.95; metastatic TNBC, 0.37). SOX10 had the lowest overall sensitivity (0.12) but was elevated in metastatic TNBC, even higher than GATA3 (0.59 vs. 0.37). The combination of GATA3, SOX10, and PAX8 expression showed the highest detection rate (MBC, 0.94; metastatic non-TNBC, 0.95; metastatic TNBC, 0.93).

CONCLUSION

We recommend combining GATA3, SOX10, PAX8 expression profiling to confirm breast as the site of origin in metastatic MBC.

FOXC1

CONTEXT.—

Few studies have investigated the features of FOXC1 protein expression in invasive breast cancer subtypes as defined by immunohistochemistry (IHC)-based surrogate molecular classification.

OBJECTIVE.—

To investigate the diagnostic utility of the IHC-based FOXC1 test in breast cancer subtyping and to evaluate the correlation between FOXC1 expression and clinicopathologic parameters in triple-negative breast cancer (TNBC).

DESIGN.—

FOXC1 expression was evaluated with IHC in a large cohort of 2443 patients with breast cancer. Receiver operating characteristic (ROC) curves were used to assess the diagnostic ability of FOXC1 expression to predict the triple-negative phenotype and to identify the best cutoff value. FOXC1 expression was correlated with the clinicopathologic parameters of TNBC.

RESULTS.—

The expression rate of FOXC1 in TNBC was significantly higher than in other subtypes. The area under the ROC curve confirmed the high diagnostic value of FOXC1 for the prediction of the triple-negative phenotype. The cutoff value of 1% showed a maximized sum of sensitivity and specificity. In TNBC, FOXC1 expression was significantly associated with aggressive tumor phenotypes. Furthermore, FOXC1 expression was primarily observed in invasive breast carcinoma of no special type and metaplastic carcinoma but rarely in invasive carcinoma with apocrine differentiation. Correspondingly, FOXC1 expression was significantly associated with the expression of basal markers but was negatively correlated with apocrine-related markers in TNBC.

CONCLUSIONS.—

In conclusion, FOXC1 is a highly specific marker for the triple-negative phenotype. Moreover, immunohistochemical detection of FOXC1 expression can be used as an additional diagnostic tool for the triple-negative phenotype and subclassification in TNBC.

SOX10 regulates melanoma immunogenicity through an IRF4-IRF1 axis

Loss-of-function mutations of JAK1/2 impair cancer cell responsiveness to IFN-γ and immunogenicity. Therefore, an understanding of compensatory pathways to activate IFN-γ signaling in cancer cells is clinically important for the success of immunotherapy. Here we demonstrate that the transcription factor SOX10 hinders immunogenicity of melanoma cells through the IRF4-IRF1 axis. Genetic and pharmacological approaches revealed that SOX10 repressed IRF1 transcription via direct induction of a negative regulator, IRF4. The SOX10-IRF4-IRF1 axis regulated PD-L1 expression independently of JAK-STAT pathway activity, and suppression of SOX10 increased the efficacy of combination therapy with an anti-PD-1 antibody and HDAC inhibitor against a clinically relevant melanoma model. Thus, the SOX10-IRF4-IRF1 axis serves as a potential target that can bypass JAK-STAT signaling to immunologically warm up melanoma with a "cold" tumor immune microenvironment.

SOX10 is a highly specific biomarker of basal-like breast cancer

AIMS

Basal-like breast cancer is an aggressive molecular subtype associated with younger age and early relapse. Most cases lack expression of estrogen receptor (ER), progesterone receptor, and human epidermal growth factor receptor 2, limiting targeted therapeutic options. Basal-like breast cancer is defined by expression of genes in the outer/basally-located epithelial layer of mammary glands including those encoding cytokeratins 5 and 14, and epidermal growth factor receptor (EGFR). SOX10, a readily available immunohistochemical stain, is expressed in a subset of breast cancers, particularly triple-negative carcinomas. In this study, we sought to (i) assess the association between SOX10 expression and intrinsic molecular subtypes as defined by PAM50 gene expression and (ii) compare the performance of SOX10 to other surrogate markers of basal-like subtype, including CK5, EGFR, nestin and INPP4b.

METHODS AND RESULTS

SOX10 immunostaining was performed on tissue microarrays constructed from a contemporary series enriched for ER negative and weakly positive cancers, which had also undergone PAM50 gene profiling. A total of 211 cases were informative for both SOX10 immunohistochemistry (IHC) and PAM50 subtype, including 103 basal-like. Staining for SOX10 was positive in 73/103 basal-like cancers and only 2/108 other subtypes (p<0.001), resulting in a sensitivity of 70.9% and a specificity of 98.1%. SOX10 was more specific than the other tested basal-markers and the results were independent of estrogen receptor status.

CONCLUSIONS

SOX10 is a moderately sensitive, but highly specific IHC biomarker for the basal-like intrinsic subtype of breast cancer, which unlike other commonly used IHC biomarkers, is independent of hormone receptor status.

Triple-negative breast lobular carcinoma: a luminal androgen receptor carcinoma with specific ESRRA mutations

Primary triple-negative invasive lobular breast carcinomas (TN-ILCs), which do not express hormone receptors and HER2 at diagnosis, are rare and poorly known. In this study, we analyzed the largest TN-ILC series ever reported in the literature, in comparison to phenotypically similar breast tumor subtypes: triple-negative invasive ductal carcinoma (TN-IDC) and hormone receptor-positive invasive lobular carcinoma (HR + ILC). All primary TN-ILCs registered in our database between 2000 and 2018 (n = 38) were compared to tumors from control groups, matched by stage and Elston/Ellis grade, with regard to clinical, pathologic, and immunohistochemical characteristics. A comparative molecular analysis (whole-exome and RNA sequencing using next-generation technology) was also performed. We found that TN-ILC patients were older than those with HR + ILC (P = 0.002) or TN-IDC (P < 0.001). Morphologically, TN-ILCs had aggressive phenotypes, with more pleomorphism (P = 0.003) and higher nuclear grades than HR + ILCs (P = 0.009). Immunohistochemistry showed that TN-ILCs less frequently expressed basal markers (CK5/6, EGFR and SOX10) than TN-IDCs (P < 0.001), while androgen receptor (AR) positivity was more prevalent (P < 0.001). Survival curves analysis did not show differences between TN-ILC and TN-IDC patients, while overall and distant metastasis-free survival were significantly worse compared to those with HR + ILCs (P = 0.047 and P = 0.039, respectively). At a molecular level, we found that TN-ILCs had particular transcriptomic profiles, characterized by increased AR signaling, and associated with frequent alterations in the PI3K network and ERBB2. Interestingly, whole-exome analysis also identified three specific recurrent ESRRA hotspot mutations in these tumors, which have never been described in breast cancer to date and which were absent in the other two tumor subtypes. Our findings highlight that TN-ILC is a unique aggressive breast cancer associated with elderly age, which belong to the luminal androgen receptor subtype as determined by immunohistochemistry and transcriptomic profiling. Moreover, it harbors specific molecular alterations (PI3K, ERBB2 and ESRRA) which may pave the way for new targeted therapeutic strategies.

AKT-mediated phosphorylation of Sox9 induces Sox10 transcription in a murine model of HER2-positive breast cancer

Background

Approximately 5–10% of HER2-positive breast cancers can be defined by low expression of the Ste20-like kinase, SLK, and high expression of SOX10. Our lab has observed that genetic deletion of SLK results in the induction of Sox10 and significantly accelerates tumor initiation in a HER2-induced mammary tumor model. However, the mechanism responsible for the induction of SOX10 gene expression in this context remains unknown.

Methods

Using tumor-derived cell lines from MMTV-Neu mice lacking SLK and biochemical approaches, we have characterized the signaling mechanisms and relevant DNA elements driving Sox10 expression.

Results

Biochemical and genetic analyses of the SOX10 regulatory region in SLK-deficient mammary tumor cells show that Sox10 expression is dependent on a novel −7kb enhancer that harbors three SoxE binding sites. ChIP analyses demonstrate that Sox9 is bound to those elements in vivo. Our data show that AKT can directly phosphorylate Sox9 in vitro at serine 181 and that AKT inhibition blocks Sox9 phosphorylation and Sox10 expression in SLK(-/-) tumor cells. AKT-mediated Sox9 phosphorylation increases its transcriptional activity on the Sox10 −7kb enhancer without altering its DNA-binding activity. Interestingly, analysis of murine and human mammary tumors reveals a direct correlation between the levels of active phospho-Sox9 S181 and Sox10 expression.

Conclusions

Our results have identified a novel Sox10 enhancer and validated Sox9 as a direct target for AKT. As Sox10 is a biomarker for triple-negative breast cancers (TNBC), these findings might have major implications in the targeting and treatment of those cancers.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13058-021-01435-6.

SOX factors as cell-state regulators in the mammary gland and breast cancer

Emerging evidence has shown that several SOX family transcription factors are key regulators of stem/progenitor cell fates in the mammary gland. These cell-fate regulators are often upregulated in breast cancer and contribute to tumor initiation and progression. They induce lineage plasticity and the epithelial-mesenchymal transition, which promotes tumor invasion, metastasis, and therapeutic resistance. SOX factors act through modulating multiple oncogenic signaling pathways in breast cancer. In addition to the cell-autonomous functions, new evidence suggests they can shape the tumor immune microenvironment. Here, we will review the molecular and functional evidence linking SOX factors with mammary gland development and discuss how these cell-fate regulators are co-opted in breast cancer.

The Added Value of SOX10 Immunohistochemistry to Other Breast Markers in Identifying Cytokeratin 5-Positive Triple Negative Breast Cancers as of Mammary Origin

AIMS

Triple-negative breast cancer (TNBC) represents a specific group that lacks the expression of estrogen receptors, progesterone receptors, and human epidermal growth factor receptor-2 and might also lack the expression other breast markers like GATA3, mammaglobin (MG), GCDFP15 (growth cystic disease fluid protein 15), and NYBR1; when this occurs, proving the breast origin of a metastasis is a challenging task. In the present study, we assessed the added value of SOX10 immunohistochemistry to known GATA3, MG, GCDFP15, and NY-BR-1 statuses in a series of CK5-positive primary TNBCs.

METHODS

Tissue microarrays were made from the formalin-fixed and paraffin-embedded blocks of 120 TNBCs, and 3-4-mm-thick sections were immunostained for SOX10. The cut-off for a positive reaction was at least 10% of tumor cells staining.

RESULTS

In our cohort, SOX10 positivity was seen in 82/119 cases, 61, 74, 76, and 82 all of which were GATA3, MG, GCDFP15, and NY-BR-1 negative, respectively. Of the SOX10 negative cases, 12 stained with at least another breast marker. Nevertheless, 25/119 (21%) cases remained negative with all markers assessed.

DISCUSSION

SOX10 proved to be the most commonly positive breast marker in our CK5 expressing TNBCs, but the other markers also had some additive value to SOX10.

Cytokeratin 7, GATA3, and SOX-10 is a Comprehensive Panel in Diagnosing Triple Negative Breast Cancer Brain Metastases

Following lung cancer, breast cancer is the second most common metastatic tumor to the brain, of which triple-negative breast cancer (TNBC) and human epidermal growth factor receptor 2+ (HER2+) breast cancer are the most common subtypes. TNBC does not have standard immunoprofiles and can be difficult to distinguish from other metastases. A tissue microarray was created from 47 patients with breast cancer metastases to the brain and 12 paired breast primaries. Of 47 breast cancer metastases, 24 were HER2+, 14 were TNBC, and 9 were luminal. Forty-five were cytokeratin 7 (CK7) positive, 36 were GATA-binding protein 3 (GATA3) positive, 7 were Sry-related HMg-Box gene 10 (SOX-10) positive, 20 were mammaglobin positive, and 19 were gross cystic disease fluid protein 15 positive. At least one of the CK7, GATA3, or SOX-10 was positive in all TNBC metastases. A panel of CK7, GATA3, and SOX-10 is complementary in the diagnosis of breast cancer brain metastasis. SOX-10 appears to be a specific but not particularly sensitive marker in this context.

Novel uses of immunohistochemistry in breast pathology: interpretation and pitfalls

Immunohistochemistry is an essential component of diagnostic breast pathology. The emergence of novel assays and applications is accompanied by new interpretation criteria and potential pitfalls. Immunohistochemistry assists in supporting breast origin for primary or metastatic carcinomas and identifying non-mammary metastases to the breast; however, no single immunostain is perfectly sensitive nor specific. GATA3 and Sox10 are particularly useful immunostains to identify triple negative breast carcinoma, which are often negative for other markers of mammary differentiation. Sox10 labeling is a major potential diagnostic pitfall, as Sox10 and S-100 label both triple negative breast carcinoma and metastatic melanoma; a pan-cytokeratin immunostain should always be included for this differential diagnosis. Novel immunohistochemistry serves as surrogates for the molecular alterations unique to several of special-type breast carcinomas, including the use of MYB in adenoid cystic carcinoma, pan-TRK in secretory carcinoma, and mutant IDH2 in tall cell carcinoma with reversed polarity (TCCRP). In addition, PD-L1 immunohistochemistry is an emerging, albeit imperfect, biomarker for breast cancer immunotherapy, with different assay parameters and scoring criteria in breast carcinoma compared to other tumor types. The expanding repertoire of novel immunohistochemistry provides additional diagnostic tools and biomarkers that improve diagnostic breast pathology and patient care.

Sex-Determining Region Y Chromosome-Related High-Mobility-Group Box 10 in Cancer: A Potential Therapeutic Target

Sex-determining region Y-related high mobility group-box 10 (SOX10), a member of the SOX family, has recently been highlighted as an essential transcriptional factor involved in developmental biology. Recently, the functionality of SOX 10 has been increasingly revealed by researchers worldwide. It has been reported that SOX10 significantly regulates the proliferation, migration, and apoptosis of tumors and is closely associated with the progression of cancer. In this review, we first introduce the basic background of the SOX family and SOX10 and then discuss the pathophysiological roles of SOX10 in cancer. Besides, we enumerate the application of SOX10 in the pathological diagnosis and therapeutic potential of cancer. Eventually, we summarize the potential directions and perspectives of SOX10 in neoplastic theranostics. The information compiled herein may assist in additional studies and increase the potential of SOX10 as a therapeutic target for cancer.

The transcription factor Sox10 is an essential determinant of branching morphogenesis and involution in the mouse mammary gland

The high mobility group-domain containing transcription factor Sox10 is an essential regulator of developmental processes and homeostasis in the neural crest, several neural crest-derived lineages and myelinating glia. Recent studies have also implicated Sox10 as an important factor in mammary stem and precursor cells. Here we employ a series of mouse mutants with constitutive and conditional Sox10 deficiencies to show that Sox10 has multiple functions in the developing mammary gland. While there is no indication for a requirement of Sox10 in the specification of the mammary placode or descending mammary bud, it is essential for both the prenatal hormone-independent as well as the pubertal hormone-dependent branching of the mammary epithelium and for proper alveologenesis during pregnancy. It furthermore acts in a dosage-dependent manner. Sox10 also plays a role during the involution process at the end of the lactation period. Whereas its effect on epithelial branching and alveologenesis are likely causally related to its function in mammary stem and precursor cells, this is not the case for its function during involution where Sox10 seems to work at least in part through regulation of the miR-424(322)/503 cluster.

Predictive markers for pathological complete response after neo-adjuvant chemotherapy in triple-negative breast cancer

A combination of Sox10 and GATA3 was previously identified as a marker for metastatic triple-negative breast cancer (TNBC), but it is uncertain whether their expression is associated with pathological complete response (pCR) after neoadjuvant chemotherapy (NAC). This study investigates the predictive value of clinicopathological characteristics, as well as protein expression of Sox10, GATA3, p53 and p63, in a consecutive series of TNBC patients treated with NAC. Archived hematoxylin & eosin stained slides of core biopsies and resection specimens from 35 TNBC patients were reviewed. The following clinicopathological characteristics were determined at the biopsy level: age at diagnosis, cancer type, Nottingham grade, lympho-vascular invasion, syncytial growth, necrosis, clear cell differentiation, myxoid peritumor stroma, stromal tumor-infiltrating lymphocytes (sTILs) and presence of an in situ component. The MD Anderson residual cancer burden (RCB) score and corresponding RCB class were determined. Immunohistochemistry for Sox10, p53, GATA3 and p63 was performed at the biopsy level. sTILs, either as a continuous or as a dichotomous variable, were the only parameter that was significantly associated with pCR in univariable and multivariable analyses. Assessment of sTILs showed moderate to good interobserver agreement. High sTILs (≥40%) were significantly associated with increased pCR rates, and this association was observer-independent. This retrospective study of a consecutive community-based cohort of TNBC patients confirms that sTILs are a robust, observer-independent predictor for therapeutic response after NAC. The combination of Sox10, GATA3 and p53 immunoreactivity is unlikely to harbor any predictive value for pCR in TNBC.

S-100 protein and SOX10-positive breast carcinoma mimicking metastatic melanoma

We present a case detailing a 70-year-old female with a history of triple-negative breast carcinoma (TNBC) of the left breast and contralateral stage pT2a nodular melanoma of the right upper arm who underwent sentinel lymph node biopsy of the right axilla demonstrating a metastatic epithelioid tumor that was strongly positive for S-100 protein and SOX10. The tumor cells were negative for HMB-45 and Melan-A and positive for CK7 and other breast markers (GCDFP15, mammaglobin, and GATA3). While concerning for metastatic melanoma based on clinical history and initial immunohistochemistry, tumor morphology and subsequent immunohistochemistry was supportive of metastatic breast adenocarcinoma. This case demonstrates a rare but perilous diagnostic pitfall of triple-negative breast carcinomas that strongly and diffusely express S-100 protein and SOX10 mimicking melanoma.

Sry-related high-mobility-group/HMG box 10 (SOX10) as a sensitive marker for triple-negative breast cancer

AIMS

Confirmation of a breast origin for triple-negative breast cancer (TNBC) is sometimes problematic. The traditional breast markers GATA-binding protein 3 (GATA3), mammaglobin (MGB) and gross cystic disease fluid protein 15 (GCDFP15) have shown limitations in identifying TNBC. Here, we aimed to examine the diagnostic potential of the newly proposed TNBC marker, Sry-related high-mobility-group/HMG box 10 (SOX10).

METHODS AND RESULTS

We analysed and compared SOX10 expression with GATA3, MGB and GCDFP15 expression in a test cohort of 1838 invasive breast cancers (IBCs) by using tissue microarrays. The findings from the test cohort were further examined with a validation cohort of 42 TNBCs in whole sections. The overall expression rates of SOX10, GATA3, MGB and GCDFP15 were 6.9%, 83.1%, 47.0%, and 34.8%, respectively. Among the TNBCs within this cohort, the expression rates of SOX10, GATA3, MGB and GCDFP15 were 31.3%, 34.5%, 27.9%, and 25.2%, respectively. SOX10 was strongly associated with TNBC (P < 0.001), whereas all other traditional markers were associated with non-TNBC (P < 0.001 for all). In addition, SOX10 was more correlated to basal-like breast cancer (BLBC) (P = 0.001) than five-marker-negative subtype among the TNBCs. A high expression rate of SOX10 (81%) was confirmed in the validation cohort. Additionally, SOX10 expression was inversely correlated with GATA3 and GCDFP15 expression, so they may complement each other in TNBC detection. The SOX10-GATA3 combination yielded a sensitivity of 60.3% for TNBC detection in the test cohort.

CONCLUSION

SOX10 is a reliable marker for identifying TNBC, and complements GATA3. The SOX10-GATA3 combination may be used as a sensitive TNBC marker.

Immunohistological Expression of SOX-10 in Triple-Negative Breast Cancer: A Descriptive Analysis of 113 Samples

Background: SRY-related HMG-box 10 (SOX-10) is commonly expressed in triple negative breast cancer (TNBC). However, data on the biological significance of SOX-10 expression is limited. Therefore, we investigated immunhistological SOX-10 expression in TNBC and correlated the results with genetic alterations and clinical data. Methods: A tissue microarray including 113 TNBC cases was stained by SOX-10. Immunohistological data of AR, BCL2, CD117, p53 and Vimentin was available from a previous study. Semiconductor-based panel sequencing data including commonly altered breast cancer genes was also available from a previous investigation. SOX-10 expression was correlated with clinicopathological, immunohistochemical and genetic data. Results: SOX-10 was significantly associated with CD117 and Vimentin, but not with AR expression. An association of SOX-10 with BCL2, EGFR or p53 staining was not observed. SOX-10-positive tumors harbored more often TP53 mutations but less frequent mutations of PIK3CA or alterations of the PIK3K pathway. SOX-10 expression had no prognostic impact either on disease-free, distant disease-free, or overall survival. Conclusions: While there might be a value of SOX-10 as a differential diagnostic marker to identify metastases of TNBC, its biological role remains to be investigated.

Cancer and SOX proteins: New insight into their role in ovarian cancer progression/inhibition

Transcription factors are potential targets in disease therapy, particularly in cancer. This is due to the fact that transcription factors regulate a variety of cellular events, and their modulation has opened a new window in cancer therapy. Sex-determining region Y (SRY)-related high-mobility group (HMG) box (SOX) proteins are potential transcription factors that are involved in developmental processes such as embryogenesis. It has been reported that abnormal expression of SOX proteins is associated with development of different cancers, particularly ovarian cancer (OC). In the present review, our aim is to provide a mechanistic review of involvement of SOX members in OC. SOX members may suppress and/or promote aggressiveness and proliferation of OC cells. Clinical studies have also confirmed the potential of transcription factors as diagnostic and prognostic factors in OC. Notably, studies have demonstrated the relationship between SOX members and other molecular pathways such as ST6Ga1-I, PI3K, ERK and so on, leading to more complexity. Furthermore, SOX members can be affected by upstream mediators such as microRNAs, long non-coding RNAs, and so on. It is worth mentioning that the expression of each member of SOX proteins is corelated with different stages of OC. Furthermore, their expression determines the response of OC cells to chemotherapy. These topics are discussed in this review to shed some light on role of SOX transcription factors in OC.

Combined SOX10 GATA3 is most sensitive in detecting primary and metastatic breast cancers: a comparative study of breast markers in multiple tumors

PURPOSE

For invasive breast cancer (IBC), high SOX10 expression was reported particularly in TNBC. This raised the possibility that SOX10 may complement other breast markers for determining cancers of breast origin.

METHODS

Here, we compared the expression of SOX10 with other breast markers (GATA3, mammaglobin and GCDFP15) and their combined expression in a large cohort of IBC together with nodal metastases. We have also evaluated the expression of GATA3 and SOX10 in a wide spectrum of non-breast carcinomas to assess their value as breast specific markers.

RESULTS

Compared with other markers, SOX10 showed lower overall sensitivity (6.5%), but higher sensitivity in TNBC (31.4%) than other breast markers including GATA3 (29.7% for TNBC). Its expression demonstrated the highest concordance between the paired IBC and nodal metastases (96.4%, κ = 0.663) among all the breast markers. More importantly, SOX10 identified many GATA3-negative TNBC, thus the SOX10/GATA3 combination was the most sensitive marker combination for IBC (86.6%). For non-breast carcinoma, a high SOX10/GATA3 expression rate was found in melanoma (77.9%, predominately expressed SOX10), urothelial carcinoma (82.0%, predominately expressed GATA3) and salivary gland tumors (69.4%). Other carcinomas, including cancers from lungs, showed very low expression for the marker combination.

CONCLUSIONS

The data suggested that SOX10/GATA3 combination can be used for differentiating metastases of breast and multiple non-breast origins. However, the differentiation with melanoma and urothelial tumors required more careful histologic examination, thorough clinical information and additional site-specific IHC markers. For salivary gland tumors, the overlapping tumor types with IBC renders the differentiation difficult.

High frequency of p16 and SOX10 coexpression but not androgen receptor expression in triple-negative breast cancers

Triple-negative breast cancers (TNBCs) represent approximately 12-17% of all breast cancers and have distinctively aggressive clinical courses. Because routine biomarkers for breast cancer do not apply for TNBCs, it is essential to find novel prognostic markers and potential targets for therapeutic agents. p16 and SOX10 are emerging biomarkers with relatively unexplored expressions in TNBCs. We present an analysis of the expression of p16 and SOX10 in combination with that of androgen receptor (AR) and cytokeratin (CK) 5/6 in TNBCs. In addition, we used tissue microarrays (TMAs) to compare frequencies of p16 and SOX10 between TNBCs and non-TNBCs. Fifty-six TNBC samples with clinical data were stained immunohistochemically with p16, SOX10, AR, and CK5/6. Fifty-four cases (96.4%) were invasive ductal carcinoma, not otherwise specified, and 46 cases (82.1%) were Nottingham histologic grade 3. The majority of TNBC cases were positive for p16 (n = 44; 78.6%) and SOX10 (n = 48; 85.7%). AR was positive in 15 cases (26.8%). CK5/6 was positive in 24 cases (42.9%), which were classified as basal-like breast cancer (BLBC) subtype. The frequencies of p16 and SOX10 expression in BLBC and non-BLBC subtypes did not reveal significant statistical difference in a separate analysis. Using archived TNBC and non-TNBC TMAs, we observed that 56% of TNBC cases were positive for p16 compared with 16% of non-TNBC cases (p-value <0.0001). SOX10 was positive in 80% of TNBC cases compared with 35% of non-TNBC cases (p-value <0.0001). A significant correlation was observed between p16 and SOX10 coexpression in TNBC cases (n = 56/80, p = 0.02) but not in non-TNBC cases (n = 23/348; p = 0.626). In conclusion, p16 and SOX10 are frequently expressed in TNBC, regardless of CK5/6 expression. Furthermore, p16 and SOX10 are often coexpressed in TNBCs compared with non-TNBCs.