p63, a p53 homologue, is a selective nuclear marker of myoepithelial cells of the human breast

Involvement of N4BP2L1, PLEKHA4, and BEGAIN genes in breast cancer and muscle cell development

Patients with breast cancer show altered expression of genes within the pectoralis major skeletal muscle cells of the breast. Through analyses of The Cancer Genome Atlas (TCGA)-breast cancer (BRCA), we identified three previously uncharacterized putative novel tumor suppressor genes expressed in normal muscle cells, whose expression was downregulated in breast tumors. We found that NEDD4 binding protein 2-like 1 (N4BP2L1), pleckstrin homology domain-containing family A member 4 (PLEKHA4), and brain-enriched guanylate kinase-associated protein (BEGAIN) that are normally highly expressed in breast myoepithelial cells and smooth muscle cells were significantly downregulated in breast tumor tissues of a cohort of 50 patients with this cancer. Our data revealed that the low expression of PLEKHA4 in patients with menopause below 50 years correlated with a higher risk of breast cancer. Moreover, we identified N4BP2L1 and BEGAIN as potential biomarkers of HER2-positive breast cancer. Furthermore, low BEGAIN expression in breast cancer patients with blood fat, heart problems, and diabetes correlated with a higher risk of this cancer. In addition, protein and RNA expression analysis of TCGA-BRCA revealed N4BP2L1 as a promising diagnostic protein biomarker in breast cancer. In addition, the in silico data of scRNA-seq showed high expression of these genes in several cell types of normal breast tissue, including breast myoepithelial cells and smooth muscle cells. Thus, our results suggest their possible tumor-suppressive function in breast cancer and muscle development.

Carrying SNP rs17506395 (T > G) in TP63 gene and CCR5Δ32 mutation associated with the occurrence of breast cancer in Burkina Faso

Genetic alterations in the TP63 (GenBank: NC_000003.12, ID: 8626) and CCR5 (receptor 5 chemokine co-receptor) (GenBank: NC_000003.12, ID: 1234) genes may increase the risk of developing breast cancer. The aim of this study was to investigate the probable involvement of polymorphisms rs17506395 in the TP63 (tumour protein 63) gene and the CCR5Δ32 mutation in the occurrence of breast cancer in Burkina Faso. This case-control study included 72 patients and 72 controls. Genotyping of SNP rs17506395 (TP63) was performed by polymerase chain reaction-restriction fragment length polymorphism, and genotyping of the CCR5Δ32 mutation was performed by allele-specific oligonucleotide polymerase chain reaction. For SNP rs17506395 (TP63), the genotypic frequencies of wild-type homozygotes (TT) and heterozygotes (TG) were, respectively, 27.72 and 72.22% in cases and 36.11 and 63.89% in controls. No mutated homozygotes (GG) were observed. For the CCR5Δ32 mutation, the genotypic frequencies of wild-type homozygotes (WT/WT) and heterozygotes (WT/Δ32) were 87.5 and 13.5%, respectively, in the cases and 89.29 and 10.71%, respectively, in the controls. No mutated homozygotes (Δ32/Δ32) were observed. None of the polymorphisms rs17506395 of the TP63 gene (OR = 1.47, 95% CI = 0.69-3.17, P = 0.284) and the CCR5Δ32 mutation (OR = 1.32, 95% CI = 0.46-3.77; P = 0.79) were associated with the occurrence of breast cancer in this study.

Tumour 63 protein (p63) in breast pathology: biology, immunohistochemistry, diagnostic applications, and pitfalls

Tumour protein 63 (p63) is a transcription factor of the p53 gene family, encoded by the TP63 gene located at chromosome 3q28, which regulates the activity of genes involved in growth and development of the ectoderm and derived tissues. p63 protein is normally expressed in the nuclei of the basal cell layer of glandular organs, including breast, in squamous epithelium and in urothelium. p63 immunohistochemical (IHC) staining has several applications in diagnostic breast pathology. It is commonly used to demonstrate myoepithelial cells at the epithelial stromal interface to differentiate benign and in situ lesions from invasive carcinoma and to characterize and classify papillary lesions including the distinction of breast intraduct papilloma from skin hidradenoma. p63 IHC is also used to identify and profile lesions showing myoepithelial cell and/or squamous differentiation, e.g. adenomyoepithelioma, salivary gland-like tumours including adenoid cystic carcinoma, and metaplastic breast carcinoma including low-grade adenosquamous carcinoma. This article reviews the applications of p63 IHC in diagnostic breast pathology and outlines a practical approach to the diagnosis and characterization of breast lesions through the identification of normal and abnormal p63 protein expression. The biology of p63, the range of available antibodies with emphasis on staining specificity and sensitivity, and pitfalls in interpretation are also discussed. The TP63 gene in humans, which shows a specific genomic structure, resulting in either TAp63 (p63) isoform or ΔNp63 (p40) isoform. As illustrated in the figure, both isoforms contain a DNA-binding domain (Orange box) and an oligomerization domain (Grey box). TAp63 contains an N-terminal transactivation (TA) domain (Green box), while ΔNp63 has an alternative terminus (Yellow box). Antibodies against conventional pan-p63 (TP63) bind to the DNA binding domain common to both isoforms (TAp63 and p40) and does not distinguish between them. Antibodies against TAp63 bind to the N-terminal TA domain, while antibodies specific to ΔNp63 (p40) bind to the alternative terminus. Each isoform has variant isotypes (α, β, γ, δ, and ε).

p63: a crucial player in epithelial stemness regulation

Epithelial tissue homeostasis is closely associated with the self-renewal and differentiation behaviors of epithelial stem cells (ESCs). p63, a well-known marker of ESCs, is an indispensable factor for their biological activities during epithelial development. The diversity of p63 isoforms expressed in distinct tissues allows this transcription factor to have a wide array of effects. p63 coordinates the transcription of genes involved in cell survival, stem cell self-renewal, migration, differentiation, and epithelial-to-mesenchymal transition. Through the regulation of these biological processes, p63 contributes to, not only normal epithelial development, but also epithelium-derived cancer pathogenesis. In this review, we provide an overview of the role of p63 in epithelial stemness regulation, including self-renewal, differentiation, proliferation, and senescence. We describe the differential expression of TAp63 and ΔNp63 isoforms and their distinct functional activities in normal epithelial tissues and in epithelium-derived tumors. Furthermore, we summarize the signaling cascades modulating the TAp63 and ΔNp63 isoforms as well as their downstream pathways in stemness regulation.

Syringomatous adenoma of the nipple: A case series and systematic review

Key Clinical Message

SAN should be considered in the setting of nipple discharge or morphology changes with typical histological findings. There are limited published cases of SAN, and workup of this pathology is still not clear to date.

Abstract

Syringomatous adenoma of the nipple (SAN) is known to be a rare benign breast neoplasm. With a few cases documented in the literature, preoperatively diagnosing this tumor is a challenge, which often leads to invasive procedure such as mass excision with nipple removal. This study was aimed at presenting a case report of SAN and to conduct a review of published cases. Literature search was conducted through PubMed databases. Articles published from year 1983 to March of 2022 were included. Only histologically confirmed cases of SAN were included. The review was performed according to the PRISMA guidelines. Twenty-eight cases, including the newly reported case, were included in the review after going through inclusion criteria. The mean age at diagnosis was 44 ± 16 years. 7% were male. The most common presentation was palpable mass. Preoperative biopsy was done for 9 cases, out of which 7 did not indicate typical histopathological characteristic of SAN. Most common treatment was wide local excision with nipple removal. Immunohistochemical staining of the resected tumor was performed in 16 cases postoperatively. 32.1% (9/28) utilized p63 in constellation with histologic findings. Five cases that utilized staining also used Estrogen Receptor (ER) marker, while three used progesterone receptor (PR) marker. SAN should be considered in the setting of nipple discharge or morphology changes with typical histological findings. There are limited published cases of SAN, and workup of this pathology is still not clear to date. The case presented here and our comprehensive literature review suggest that pathohistological findings of SAN can be heterogeneous. Clinicians would also benefit from recognizing these variances. Further research and reported cases are needed to confidently diagnose SAN, which may open doors for less aggressive surgical treatment or surveillance option for asymptomatic patients.

Isogenic Mammary Models of Intraductal Carcinoma Reveal Progression to Invasiveness in the Absence of a Non-Obligatory In Situ Stage

In breast cancer, progression to invasive ductal carcinoma (IDC) involves interactions between immune, myoepithelial, and tumor cells. Development of IDC can proceed through ductal carcinoma in situ (DCIS), a non-obligate, non-invasive stage, or IDC can develop without evidence of DCIS and these cases associate with poorer prognosis. Tractable, immune-competent mouse models are needed to help delineate distinct mechanisms of local tumor cell invasion and prognostic implications. To address these gaps, we delivered murine mammary carcinoma cell lines directly into the main mammary lactiferous duct of immune-competent mice. Using two strains of immune-competent mice (BALB/c, C57BL/6), one immune-compromised (severe combined immunodeficiency; SCID) C57BL/6 strain, and six different murine mammary cancer cell lines (D2.OR, D2A1, 4T1, EMT6, EO771, Py230), we found early loss of ductal myoepithelial cell differentiation markers p63, α-smooth muscle actin, and calponin, and rapid formation of IDC in the absence of DCIS. Rapid IDC formation also occurred in the absence of adaptive immunity. Combined, these studies demonstrate that loss of myoepithelial barrier function does not require an intact immune system, and suggest that these isogenic murine models may prove a useful tool to study IDC in the absence of a non-obligatory DCIS stage-an under-investigated subset of poor prognostic human breast cancer.

ΔNp63 drives dysplastic alveolar remodeling and restricts epithelial plasticity upon severe lung injury

The lung exhibits a robust, multifaceted regenerative response to severe injuries such as influenza infection, during which quiescent lung-resident epithelial progenitors participate in two distinct reparative pathways: functionally beneficial regeneration via alveolar type 2 (AT2) cell proliferation and differentiation, and dysplastic tissue remodeling via intrapulmonary airway-resident basal p63+ progenitors. Here we show that the basal cell transcription factor ΔNp63 is required for intrapulmonary basal progenitors to participate in dysplastic alveolar remodeling following injury. We find that ΔNp63 restricts the plasticity of intrapulmonary basal progenitors by maintaining either active or repressive histone modifications at key differentiation gene loci. Following loss of ΔNp63, intrapulmonary basal progenitors are capable of either airway or alveolar differentiation depending on their surrounding environment both in vitro and in vivo. Uncovering these regulatory mechanisms of dysplastic repair and lung basal cell fate choice highlight potential therapeutic targets to promote functional alveolar regeneration following severe lung injuries.

Molecular Markers in Urinary Bladder Cancer: Applications for Diagnosis, Prognosis and Therapy

Cancer of the urinary bladder is a neoplasm with considerable importance in veterinary medicine, given its high incidence in several domestic animal species and its life-threatening character. Bladder cancer in companion animals shows a complex and still poorly understood biopathology, and this lack of knowledge has limited therapeutic progress over the years. Even so, important advances concerning the identification of tumour markers with clinical applications at the diagnosis, prognosis and therapeutic levels have recently been made, for example, the identification of pathological BRAF mutations. Those advances are now facilitating the introduction of targeted therapies. The present review will address such advances, focusing on small animal oncology and providing the reader with an update on this field. When appropriate, comparisons will be drawn with bladder cancer in human patients, as well as with experimental models of the disease.

ERAS, a Member of the Ras Superfamily, Acts as an Oncoprotein in the Mammary Gland

Simple Summary

The genes of the RAS family are among the group of genes most frequently mutated in human cancer. ERAS is a relatively unknown gene of this family. Although ERAS is overexpressed in some tumoral samples and in several cancer cell lines of human origin, it is not known if its expression drives tumor formation or if, alternatively, its expression is a secondary event in tumoral transformation. In this report, in order to clarify the role of ERAS in mammary tumorigenesis, we studied transgenic mice expressing ERAS in myoepithelial cells of mammary and other exocrine glands and in basal cells of stratified epithelia. These mice displayed an altered development and function of the mammary glands, and suffered high-frequency tumoral lesions in the mammary glands resembling a rare human breast tumor named malignant adenomyoepithelioma. Our results clearly demonstrate that ERAS is a true oncogene able to produce mammary tumors when inappropriately expressed.

Abstract

ERAS is a relatively uncharacterized gene of the Ras superfamily. It is expressed in ES cells and in the first stages of embryonic development; later on, it is silenced in the majority of cell types and tissues. Although there are several reports showing ERAS expression in tumoral cell lines and human tumor samples, it is unknown if ERAS deregulated expression is enough to drive tumor development. In this report, we have generated transgenic mice expressing ERAS in myoepithelial basal cells of the mammary gland and in basal cells of stratified epithelia. In spite of the low level of ERAS expression, these transgenic mice showed phenotypic alterations resembling overgrowth syndromes caused by the activation of the AKT-PI3K pathway. In addition, their mammary glands present developmental and functional disabilities accompanied by morphological and biochemical alterations in the myoepithelial cells. These mice suffer from tumoral transformation in the mammary glands with high incidence. These mammary tumors resemble, both histologically and by the expression of differentiation markers, malignant adenomyoepitheliomas. In sum, our results highlight the importance of ERAS silencing in adult tissues and define a truly oncogenic role for ERAS in mammary gland cells when inappropriately expressed.

Expression of LGR5 in mammary myoepithelial cells and in triple-negative breast cancers

Lineage tracing in mice indicates that LGR5 is an adult stem cell marker in multiple organs, such as the intestine, stomach, hair follicles, ovary, and mammary glands. Despite many studies exploring the presence of LGR5 cells in human tissues, little is known about its expression profile in either human mammary tissue or pathological lesions. In this study we aim to investigate LGR5 expression in normal, benign, and malignant lesions of the human breast using RNA in situ hybridization. LGR5 expression has not been observed in normal lactiferous ducts and terminal duct lobular units, whereas LGR5-positive cells have been specifically observed in the basal myoepithelium of ducts in the regenerative tissues, ductal carcinoma in situ, and in ducts surrounded by invasive cancer cells. These findings suggest LGR5 marks facultative stem cells that are involved in post injury regeneration instead of homeostatic stem cells. LGR5 positivity was found in 3% (9 of 278 cases) of invasive breast cancers (BC), and it showed positive associations with higher histologic grades (P = 0.001) and T stages (P < 0.001), while having negative correlations with estrogen receptor (P < 0.001) and progesterone receptor (P < 0.001) expression. Remarkably, all LGR5-positive BC, except one, belong to triple-negative BC (TNBC), representing 24% (9 of 38 cases) of all of them. LGR5 histoscores have no correlations with EGFR, CK5/6, Ki-67, or P53 expression. Additionally, no β-catenin nuclear localization was observed in LGR5-positive BC, indicating that canonical Wnt pathway activation is less likely involved in LGR5 expression in BC. Our results demonstrate that LGR5 expression is induced in regenerative conditions in the myoepithelium of human mammary ducts and that its expression is only observed in TNBC subtype among all invasive BC. Further studies regarding the functional and prognostic impact of LGR5 in TNBC are warranted.

Characterization of neoplastic cells outlining the cystic space of invasive micropapillary carcinoma of the canine mammary gland

BACKGROUND

Invasive micropapillary carcinoma (IMPC) is a rare malignant breast tumor and a variant form of invasive ductal carcinoma that is an aggressive neoplasm of the human breast and canine mammary gland. The importance of the tumor microenvironment in cancer development has gradually been recognized, but little is known about the cell types outlining the cystic space of canine IMPC. This study aimed to characterize the neoplastic cells outlining the cystic space of IMPC.

RESULTS

Immunohistochemistry (IHC), immunofluorescence (IF), superresolution and transmission electron microscopy (TEM) were used to assess the cell types in the cystic areas of IMPCs. Cells expressing the mesenchymal markers alpha-smooth muscle actin (αSMA), Vimentin, and S100A4 outlined the cystic space of IMPC. Furthermore, loss of epithelial cell polarity in IMPC was shown by the localization of MUC1 at the stroma-facing surface. This protein modulates lumen formation and inhibits the cell-stroma interaction. Immunohistochemical and IF staining for the myoepithelial cell marker p63 were negative in IMPC samples. Furthermore, associated with peculiar morphology, such as thin cytoplasmic extensions outlining cystic spaces, was observed under TEM. These observations suggested cells with characteristics of myoepithelial-like cells.

CONCLUSIONS

The cells outlining the cystic space of IMPC in the canine mammary gland were characterized using IHC, IF and TEM. The presence of cells expressing αSMA, Vimentin, and S100A4 in the IMPC stroma suggested a role for tumor-associated fibroblasts in the IMPC microenvironment. The reversal of cell polarity revealed by the limited basal localization of MUC1 may be an important factor contributing to the invasiveness of IMPC. For the first time, the cystic space of canine mammary gland IMPC was shown to be delimited by myoepithelial-like cells that had lost p63 expression. These findings may enhance our understanding of the cellular microenvironment of invasive tumors to improve cancer diagnosis and treatment.

Neural EGFL like 2 expressed in myoepithelial cells and suppressed breast cancer cell migration

Breast tissue has a branching structure that contains double-layered cells, consisting primarily of luminal epithelial cells inside and myoepithelial cells outside. Ductal carcinoma in situ (DCIS) still has myoepithelial cells surrounding the cancer cells. However, myoepithelial cells disappear in invasive ductal carcinoma. In this study, we detected expression of neural EGFL like (NELL) 2 and one of its receptors, roundabout guidance receptor (ROBO) 3, in myoepithelial and luminal epithelial cells (respectively) in normal breast tissue. NELL2 also was expressed in myoepithelial cells surrounding the non-cancerous intraductal proliferative lesions and DCIS. However, the expression level and proportion of NELL2-positive cells in DCIS were lower than those in normal and non-cancerous intraductal proliferative lesions. ROBO3 expression was decreased in invasive ductal carcinoma compared to that in normal and non-cancerous intraductal proliferative lesions. An evaluation of NELL2's function in breast cancer cell lines demonstrated that full-length NELL2 suppressed cell adhesion and migration in vitro. In contrast, the N-terminal domain of NELL2 increased cell adhesion in the early phase and migration in vitro in some breast cancer cells. These results suggested that full-length NELL2 protein, when expressed in myoepithelial cells, might serve as an inhibitor of breast cancer cell migration.

The TP63 Gene Polymorphism rs17506395 is Associated with Early Breast Cancer in Cameroon

BACKGROUND

Breast cancer (BC) is a leading female cancer worldwide and cause of cancer-related death, especially in developing countries. Genetic predispositions to BC development in African population is poorly studied, and meanwhile the SNP rs17506395 in TP63 gene locus has been associated with the development of breast cancer in Asian women, no investigation has been undertaken within African population. We investigated the impact of this polymorphism in a representative African population.

METHODS

We undertook a case-control study including 335 women, of which 111 were breast cancer patients and 224 controls. Using blood-derived germline DNA, PCR-RFLP was used to investigate the polymorphism of TP63 gene at rs17506395 locus. Unconditional logistic regression was used to study the association between the TP63 gene polymorphism and risk of BC development. After stratification into different age and ethno-linguistic groups as well as menopausal status, the Cochran-Mantel-Haenszel test was used to measure significance of the associations.

RESULTS

Comparing cases with controls, no significant associations between genotype and disease development was observed. Similarly, when cases were stratified according to menopausal status and ethno-linguistic groups, no significant association was observed between genotype and disease development. However, in women of 40 years and below, TT and TG genotypes were associated with breast cancer development. The minor G allele seems to protective against early breast cancer onset OR of 0.5 (95%CI = 0.26-0.94, p = 0.03).

CONCLUSION

Our data revealed an association between rs15706395 and the risk of early breast cancer onset. The GG genotype seems to reduce the risk of early breast cancer. Larger studies are needed to confirm the potential of this SNP as biomarker for breast cancer prognostic.
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Analysis of the Transcriptome: Regulation of Cancer Stemness in Breast Ductal Carcinoma In Situ by Vitamin D Compounds

Ductal carcinoma in situ (DCIS), which accounts for one out of every five new breast cancer diagnoses, will progress to potentially lethal invasive ductal carcinoma (IDC) in about 50% of cases. Vitamin D compounds have been shown to inhibit progression to IDC in the MCF10DCIS model. This inhibition appears to involve a reduction in the cancer stem cell-like population in MCF10DCIS tumors. To identify genes that are involved in the vitamin D effects, a global transcriptomic analysis was undertaken of MCF10DCIS cells grown in mammosphere cultures, in which cancer stem-like cells grow preferentially and produce colonies by self-renewal and maturation, in the presence and absence of 1α25(OH)₂D₃ and a vitamin D analog, BXL0124. Using next-generation RNA-sequencing, we found that vitamin D compounds downregulated genes involved in maintenance of breast cancer stem-like cells (e.g., GDF15), epithelial-mesenchymal transition, invasion, and metastasis (e.g., LCN2 and S100A4), and chemoresistance (e.g., NGFR, PPP1R1B, and AGR2), while upregulating genes associated with a basal-like phenotype (e.g., KRT6A and KRT5) and negative regulators of breast tumorigenesis (e.g., EMP1). Gene methylation status was analyzed to determine whether the changes in expression induced by vitamin D compounds occurred via this mechanism. Ingenuity pathway analysis was performed to identify upstream regulators and downstream signaling pathway genes differentially regulated by vitamin D, including TP63 and vitamin D receptor -mediated canonical pathways in particular. This study provides a global profiling of changes in the gene signature of DCIS regulated by vitamin D compounds and possible targets for chemoprevention of DCIS progression to IDC in patients.

∆Np63/p40 correlates with the location and phenotype of basal/mesenchymal cancer stem-like cells in human ER+ and HER2+ breast cancers

ΔNp63, also known as p40, regulates stemness of normal mammary gland epithelium and provides stem cell characteristics in basal and HER2‐driven murine breast cancer models. Whilst ΔNp63/p40 is a characteristic feature of normal basal cells and basal‐type triple‐negative breast cancer, some receptor‐positive breast cancers express ΔNp63/p40 and its overexpression imparts cancer stem cell‐like properties in ER⁺ cell lines. However, the incidence of ER⁺ and HER2⁺ tumours that express ΔNp63/p40 is unclear and the phenotype of ΔNp63/p40⁺ cells in these tumours remains uncertain. Using immunohistochemistry with p63 isoform‐specific antibodies, we identified a ΔNp63/p40⁺ tumour cell subpopulation in 100 of 173 (58%) non‐triple negative breast cancers and the presence of this population associated with improved survival in patients with ER⁻/HER2⁺ tumours (p = 0.006). Furthermore, 41% of ER⁺/PR⁺ and/or HER2⁺ locally metastatic breast cancers expressed ΔNp63/p40, and these cells commonly accounted for <1% of the metastatic tumour cell population that localised to the tumour/stroma interface, exhibited an undifferentiated phenotype and were CD44⁺/ALDH⁻. In vitro studies revealed that MCF7 and T47D (ER⁺) and BT‐474 (HER2⁺) breast cancer cell lines similarly contained a small subpopulation of ΔNp63/p40⁺ cells that increased in mammospheres. In vivo, MCF7 xenografts contained ΔNp63/p40⁺ cells with a similar phenotype to primary ER⁺ cancers. Consistent with tumour samples, these cells also showed a distinct location at the tumour/stroma interface, suggesting a role for paracrine factors in the induction or maintenance of ΔNp63/p40. Thus, ΔNp63/p40 is commonly present in a small population of tumour cells with a distinct phenotype and location in ER⁺ and/or HER2⁺ human breast cancers.

Expression of Tumour Endothelial Marker 8 in Canine Mammary Gland Tumour Cells

The aim of this study was to investigate the expression of tumour endothelial marker 8 (TEM8) in canine mammary gland tumours (MGTs) by immunohistochemistry and to evaluate the association between tumour cell TEM8 expression and tumour histological features, histological grades and expression of luminal and basal/myoepithelial cell markers. TEM8 expression was detected in >60 % of neoplastic epithelial cells in all simple adenomas (n = 25), simple carcinomas (n = 43) and invasive micropapillary carcinomas (n = 5) studied. Six of the 18 solid carcinomas studied showed TEM8 expression in >60% of carcinoma cells present in solid structures and in 12 of the 18 solid carcinomas, <30% of the luminal structure-forming carcinoma cells showed TEM8 expression. TEM8 expression in the neoplastic cells was not associated with histological malignancy in canine MGTs. TEM8⁺ tumour cells frequently showed the luminal-like phenotype cytokeratin (CK)19⁺/p63^-/α-smooth muscle actin (SMA)^-, while most TEM8^- tumour cells exhibited the basal-like phenotype CK19^-/p63⁺/αSMA^-. These findings indicate that TEM8 may be involved in maintaining the characteristics of luminal cells in canine MGTs and that TEM8 would be useful in identifying the type of neoplastic epithelial cell in MGTs.

Thymidylate Synthase, a New Myoepithelial Biomarker for Breast Lesions

Background. The identification of myoepithelial cells (MECs) can facilitate the differential diagnosis of breast lesions. We previously found thymidylate synthase (TS) expression in the nuclei of MECs in breast tissues, which prompted us to investigate the usefulness of TS as a sensitive and specific biomarker in the differential diagnosis of breast lesions, similar to other MEC biomarkers (ie, tumor protein [P63] and cluster of differentiation 10 [CD10]). Methods. Immunohistochemistry for TS, P63, and CD10 was performed on paraffin sections from 189 breast specimens. Results. The results showed the intensity of the immunoreactive TS signal to be comparable with that of P63 in the nuclei of MECs. Furthermore, the nuclei of MECs stained strongly for TS and P63 in normal breast tissues (obtained adjacent to invasive breast lesions), benign breast lesions, and carcinoma in situ, whereas the cytoplasm of MECs stained strongly for CD10. The immunoreactive TS signal in the cytoplasm of MECs was variable in 22 out of 32 (65.6%) cases of invasive breast carcinoma and 4 out of 20 cases (20.0%) of ductal carcinoma in situ. We found no immunoreactive TS signal in the nuclei of luminal and stromal cells in breast lesions, although there was a weak positive signal in the cytoplasm of luminal and stromal cells. Conclusions. TS is a sensitive and specific MEC biomarker in the differential diagnosis of breast lesions.

Tissue regeneration and the epididymal stem cell

BACKGROUND

In most pseudostratified epithelia, basal cells represent a multipotent adult stem cell population. These cells generally remain in a quiescent state, until they are stimulated to respond to tissue damage by initiating epithelial regeneration. In the epididymis, cell proliferation occurs at a relatively slow rate under normal physiological conditions. Epididymal basal cells have been shown to share common properties with multipotent adult stem cells. The development of organoids from stem cells represents a novel approach for understanding cellular differentiation and characterization of stem cells.

OBJECTIVE

To review the literature on tissue regeneration in the epididymis and demonstrate the presence of an epididymal stem cell population.

METHODS

PubMed database was searched for studies reporting on cell proliferation, regeneration, and stem cells in the epididymis. Three-dimensional cell culture of epididymal cells was used to determine whether these can develop into organoids in a similar fashion to stem cells from other tissues.

RESULTS

The epididymal epithelium can rapidly regenerate following orchidectomy or efferent duct ligation, in order to maintain epithelial integrity. Studies have isolated a highly purified fraction of rat epididymal basal cells and reported that these cells displayed properties similar to those of multipotent adult stem cells. In two-dimensional cell culture conditions, these cells differentiated into cells which expressed connexin 26, a marker of columnar cells, and cytokeratin 8. Furthermore, three-dimensional cell culture of epididymal cells resulted in the formation of organoids, a phenomenon associated with the proliferation and differentiation of stem cells in vitro.

CONCLUSIONS

The rapid proliferation and tissue regeneration of the epididymal epithelium to preserve its integrity following tissue damage as well as the ability of cells to differentiate into organoids in vitro support the notion of a resident progenitor/stem cell population in the adult epididymis.

Caracterização anatomopatológica e imuno-histoquímica dos tumores das glândulas cutâneas em cães

RESUMO O presente estudo objetivou caracterizar os aspectos anatomopatológicos e imuno-histoquímicos dos tumores das glândulas cutâneas em cães. A caracterização morfológica seguiu a classificação atualizada da Organização Mundial de Saúde. Para a caracterização imuno-histoquímica, utilizaram-se anticorpos monoclonais primários anti-citoqueratina 14 (CK14), vimentina, p63, calponina, EGFR e Ki-67. Dos animais examinados, 66,67% (18/27) eram machos e 33,33% (9/27) fêmeas, 21 tinham raça definida e seis eram sem raça definida (SRD), com idade variando entre sete e 15 anos. Dos tumores caracterizados, 40,74% eram hepatoides (11/27), 29,63% sebáceos (8/27), 25,92% apócrinos (7/27) e 3,70% meibômio (1/27). Os tumores malignos representaram 55,56%, e os benignos 44,44%. Com esses resultados, foi possível demonstrar que os tumores das glândulas cutâneas em cães são frequentes, sem predileção por raça, sexo e com idade superior ou igual a sete anos. Os anticorpos CK 14, p63, vimentina e EGFR foram imunoexpressos nas células basais, células de diferenciação sebácea dos tumores hepatoides e de meibômio e células mioepiteliais. Entretanto, a vimentina e o EGFR não demonstraram imunomarcação para os tumores sebáceos. A calponina foi um bom marcador para as células mioepiteliais. O índice de Ki-67 foi mais acentuado nos tumores malignos em relação aos benignos. No entanto, estudos futuros utilizando maior número de casos se fazem necessários.

Breast adenosquamous cell carcinoma presented in an intracystic form

Intracystic carcinoma is not common seen in breast malignancy, here we showed a case of intracystic tumor presented in adenosquamoid differentiation. Negative in ER, PR, and HER2 makes treatment out of hormone and target therapy. After simple mastectomy with sentinel lymph node biopsy, we found isolated tumor cell over lymph node. Although AJCC takes ITCs as N0 category, the presence of ITCs is considered as a prognostic factor influencing both the overall and breast cancer-specific survival, thus we gave the patient with adjuvant chemotherapy as locally advanced breast cancer in the NCCN guideline.

Androgen Receptor Signalling Promotes a Luminal Phenotype in Mammary Epithelial Cells

Androgens influence mammary gland development but the specific role of the androgen receptor (AR) in mammary function is largely unknown. We identified cell subsets that express AR in vivo and determined the effect of AR activation and transgenic AR inhibition on sub-populations of the normal mouse mammary epithelium by flow cytometry and immunohistochemistry. Immunolocalisation of AR with markers of lineage identity was also performed in human breast tissues. AR activation in vivo significantly decreased the proportion of basal cells, and caused an accumulation of cells that expressed a basal cell marker but exhibited morphological features of luminal identity. Conversely, in AR null mice the proportion of basal mammary epithelial cells was significantly increased. Inhibition of AR increased basal but not luminal progenitor cell activity in vitro. A small population of AR-positive cells in a basal-to-luminal phenotype transition was also evident in human breast lobules. Collectively, these data support a role for AR in promoting a luminal phenotype in mammary epithelial cells.

Limbal Stem Cell Transplantation: Clinical Results, Limits, and Perspectives

Limbal stem cell deficiency (LSCD) is a clinical condition characterized by damage of cornea limbal stem cells, which results in an impairment of corneal epithelium turnover and in an invasion of the cornea by the conjunctival epithelium. In these patients, the conjunctivalization of the cornea is associated with visual impairment and cornea transplantation has poor prognosis for recurrence of the conjunctivalization. Current treatments of LSCD are aimed at replacing the damaged corneal stem cells in order to restore a healthy corneal epithelium. The autotransplantation of limbal tissue from the healthy, fellow eye is effective in unilateral LSCD but leads to depauperation of the stem cell reservoir. In the last decades, novel techniques such as cultivated limbal epithelial transplantation (CLET) have been proposed in order to reduce the damage of the healthy fellow eye. Clinical and experimental evidence showed that CLET is effective in inducing long-term regeneration of a healthy corneal epithelium in patients with LSCD with a success rate of 70%–80%. Current limitations for the treatment of LSCD are represented by the lack of a marker able to unequivocally identify limbal stem cells and the treatment of total, bilateral LSCD which requires other sources of stem cells for ocular surface reconstruction.

Co-expression network analysis of gene expression profiles of HER2+ breast cancer-associated brain metastasis

Brain metastasis occurs in ~30% of patients with breast cancer, and patients with human epidermal growth factor receptor 2 (HER2)⁺ breast cancer have a particularly high frequency of brain metastasis. Weighted gene co-expression network analysis was conducted to identify the hub differentially expressed genes from patients with HER2⁺ breast cancer between brain metastases and primary tumors. The potential candidate genes were investigated in another set of patient samples to confirm their relevance. The results indicated that a number of pathways altered significantly when breast cancer metastasized to the brain. Cyclophilin A (CypA) and ribosomal protein L17 (RPL17) were overexpressed in breast cancer-associated brain metastases, whereas tumor protein 63 (TP63) and von Willebrand factor A domain-containing 8 (VWA8) were significantly downregulated in breast cancer brain metastases. Furthermore, the expression of CypA and RPL17 in brain metastases were significantly increased compared with that in primary breast tumors, and the expression of TP63 and VWA8 in brain metastases were significantly decreased. This result indicated that the significant differences in expression observed between primary breast tumors and brain metastases were derived from significantly altered systems, including gene modules rather than single genes.

p73 Is Required for Ovarian Follicle Development and Regulates a Gene Network Involved in Cell-to-Cell Adhesion

We report that p73 is expressed in ovarian granulosa cells and that loss of p73 leads to attenuated follicle development, ovulation, and corpus luteum formation, resulting in decreased levels of circulating progesterone and defects in mammary gland branching. Ectopic progesterone in p73-deficient mice completely rescued the mammary branching and partially rescued the ovarian follicle development defects. Performing RNA sequencing (RNA-seq) on transcripts from murine wild-type and p73-deficient antral follicles, we discovered differentially expressed genes that regulate biological adhesion programs. Through modulation of p73 expression in murine granulosa cells and transformed cell lines, followed by RNA-seq and chromatin immunoprecipitation sequencing, we discovered p73-dependent regulation of a gene set necessary for cell adhesion and migration and components of the focimatrix (focal intra-epithelial matrix), a basal lamina between granulosa cells that promotes follicle maturation. In summary, p73 is essential for ovarian folliculogenesis and functions as a key regulator of a gene network involved in cell-to-cell adhesion and migration.

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p73 is required for murine ovarian folliculogenesis and proper corpus luteum formation

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p73 loss leads to defects in progesterone signaling and mammary gland branching

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In murine ovaries, p73 is expressed specifically in granulosa cells

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p73 regulates components of the granulosa cell focimatrix and migration

Technical note: p40 antibody as a replacement for p63 antibody in bovine mammary immunohistochemistry

Tumor protein 63 (p63) is a nuclear antigen found in basal epithelial cells. To date, 10 isoforms of p63 have been identified, falling into 2 major groups identified by presence or absence of an N-terminal transactivation domain (TAp63 and ΔNp63, respectively). Literature suggests that ΔNp63 is the predominant form expressed in basal epithelial cells and myoepithelial cells (MYEC). The mouse anti-p63 antibody, clone 4B1E12, has been used as a specific nuclear marker for bovine MYEC. Unfortunately, this antibody is no longer commercially available. A new mouse monoclonal antibody, clone BC28, specific to ΔNp63 (designated p40) has been developed. We hypothesized that the p40 antibody would be an appropriate substitution as a MYEC and epithelial basal cell marker. An array of archived formalin-fixed, paraffin-embedded bovine tissues were subjected to immunohistochemical staining for either p40 or p63, with a subset being dual stained for direct comparison. Positive staining for p40 and p63 was observed in serial sections of mammary, skin, rumen, salivary gland, ureter, and bladder. As predicted, negative staining for p40 and p63 was observed in testis and intestine. Dual staining for p40 and p63 in calf mammary (n = 4), lactating mammary (n = 4), rumen (n = 4), and skin (n = 4) showed nearly 100% agreement. Thus, we established that the mouse monoclonal antibody, clone BC28, is a suitable replacement for anti-p63, clone 4B1E12, as a marker of MYEC and basal epithelial cells in bovine tissues.

Low Expression of P63 and P73 in Osteosarcoma

Background

The recent discovery of two p53-related genes, p63 and p73, has revealed an additional level of complexity to the study of p53 function. Both genes encode multiple proteins arising from alternative promoter usage and splicing, with transactivation, DNA-binding, and tetramerization domains. Recent data support a role for p63 in squamous and transitional cell carcinomas, as well as in certain lymphomas and thymomas.

Methods

To characterize the involvement of p63 and p73 in the development of osteosarcoma, we analyzed the expression and mutation of TAp63 and TAp73 in six osteosarcoma cell lines and twelve osteosarcoma specimens.

Results

Semiquantitative DNA/PCR analysis revealed that eight (67%) and six (50%) out of twelve osteosarcoma specimens showed significantly reduced levels of p63 and p73 transcription, respectively. Direct sequencing of the entire coding region detected no mutations in cell lines or osteosarcoma specimens.

Conclusions

Our data suggest that low expression of p63 and p73 is relatively common in osteosarcomas and might contribute to their molecular pathogenesis.

Adenomyoepithelioma of the Breast, Presenting as a Cancer

Aims and background

Adenomyoepithelioma is a rare lesion that can involve the breast tissue. The diagnostic appearance of the lesion can give raise to a difficult differential diagnosis with breast carcinoma.

Patients and methods

We report our experience with a case of adenomyoepithelioma whose differential diagnosis with a breast carcinoma was particularly difficult, leading to surgery for definitive histology.

Discussion

Few papers are available with evidence about adenomyoepithelioma. The difficult differential diagnosis and the potentiality of malignant evolution of this lesion could in principle justify a conservative surgical approach for final histology.

Expression of c-kit in Common Benign and Malignant Breast Lesions

Aims and background

c-kit (CD117) is a transmembrane tyrosine kinase that acts as a type III receptor for mast cell growth factor. In recent years, the role of c-kit in the development of preinvasive and invasive breast carcinomas has been investigated. The aim of our study was to detect c-kit expression in the entire spectrum of common benign and malignant breast lesions in correlation with a well-studied myoepithelial or stem-cell like marker (p63).

Methods and study design

We evaluated 270 cases of benign and malignant breast lesions including fibrocystic disease, fibroadenoma, sclerosing adenosis, atypical ductal hyperplasia, ductal/lobular carcinoma in situ, and ductal/lobular/mixed type carcinoma. C-kit staining was evaluated in the cytoplasm/cell membrane in epithelial and myoepithelial cells and p63 in the nuclei of myoepithelial cells.

Results

c-kit was highly expressed (85.3%) in benign lesions (fibrocystic disease, sclerosing adenosis, fibroadenoma), and p63 expression was 95.5% in the aforementioned lesions. c-kit distribution in preinvasive and invasive lesions was as follows: ductal/lobular carcinoma in-situ, 43%/35%; ductal/lobular carcinoma, 36%/39%; and mixed type carcinoma, 20%. c-kit was highly expressed in myofibroblast/fibroblast cells only in grade III ductal/lobular carcinomas. c-kit was totally absent in stromal cells in benign lesions and in situ carcinomas whereas expression was weak in grade I and II carcinomas.

Conclusions

Combined overexpression of c-kit and p63 is indicative of benign breast lesions. In contrast, there is reduced expression of c-kit in in situ and invasive breast carcinomas, with simultaneous overexpression in the stromal cells. This suggests that c-kit may play a role in breast cancer progression. Free full text available at www.tumorionline.it

A double dealing tale of p63: an oncogene or a tumor suppressor

As a member of tumor suppressor p53 family, p63, a gene encoding versatile protein variant, has been documented to correlate with cancer formation and progression, though it is rarely mutated in cancer patients. However, it has long been controversial on whether p63 is an oncogene or a tumor suppressor. Here, we comprehensively reviewed reports on roles of p63 in development, tumorigenesis and tumor progression. According to data from molecular cell biology, genetic models and clinic research, we conclude that p63 may act as either an oncogene or a tumor suppressor gene in different scenarios: TA isoforms of p63 gene are generally tumor-suppressive through repressing cell proliferation, survival and metastasis; ΔN isoforms, however, may initiate tumorigenesis via promoting cell proliferation and survival, but inhibit tumor metastasis and progression; effects of p63 on tumor formation and progression depend on the context of the whole p53 family, and either amplification or loss of p63 gene locus can break the balance to cause tumorigenesis.

A functional interplay between Δ133p53 and ΔNp63 in promoting glycolytic metabolism to fuel cancer cell proliferation

Although ΔNp63 is known to promote cancer cell proliferation, the underlying mechanism behind its oncogenic function remains elusive. We report here a functional interplay between ΔNp63 and Δ133p53. These two proteins are co-overexpressed in a subset of human cancers and cooperate to promote cell proliferation. Mechanistically, Δ133p53 binds to ΔNp63 and utilizes its transactivation domain to upregulate GLUT1, GLUT4, and PGM expression driving glycolysis. While increased glycolysis provides cancer cells with anabolic metabolism critical for proliferation and survival, it can be harnessed for selective cancer cell killing. Indeed, we show that tumors overexpressing both ΔNp63 and Δ133p53 exhibit heightened sensitivity to vitamin C that accumulate to a lethal level due to accelerated uptake via overexpressed GLUT1. These observations offer a new therapeutic avenue that could be exploited for clinical applications.

34BetaE12 and Alfa-Methylacyl Coenzyme A Racemase (AMACR) Antibodies Better Than p63 Antibody Distinguish Normal and Neoplastic Glands in Prostatic Tissue With Thermal Artifacts

The occurrence of inked margins with crush artifact derived from the electrocauterization in radical prostatectomy and/or the presence of crushed areas with distorted glands in prostatic samples after transurethral resection of prostate (TURP) can induce a significant interobserver variability during histopathologic evaluation of specimens. The specific immunostaining for basal cell markers 34BetaE12 and p63 and for alfa-methylacyl coenzyme A racemase (AMACR) in neoplastic cells is commonly used as an ancillary tool to establish benign and malignant glands. In this study we carried out the immunohistochemical reactions for p63, 34BetaE12, and AMACR on 3 different and successive paraffin sections to discriminate malignant and benign prostatic glands, distorted and crushed by the thermal artifacts in 60 radical prostatectomies and 50 TURP samples. All prostatic acinar adenocarcinoma showed the loss of basal cell markers and expression of AMACR, whereas p63 failed to stain the basal cell layer in benign crushed prostatic glands. The same cauterized glands were steadily positive for 34BetaE12. The high percentage of p63 false negative cases in benign distorted and crushed glands could be explained by the thermal artifacts which might cause lack of p63 antigenicity. In contrast, the antigenicity of 34BetaE12 and AMACR seem not to be affected by cautery artifacts. Thus, in cauterized suspicious prostatic glands an immunohistochemistry panel including, p63, 34BetaE12, and AMACR or only 34BetaE12 is recommended. In addition, after the first evaluation with only p63, we suggest that a separate and confirmatory staining for 34BetaE12 is strongly recommended.

The Differential Regulation of Human Telomerase Reverse Transcriptase and Vascular Endothelial Growth Factor May Contribute to the Clinically More Aggressive Behavior of P63-Positive Breast Carcinomas

p63, a p53 homologue, is a myoepithelial cell marker in the normal mammary gland but p63-positive neoplastic cells may be found in up to 11% of invasive breast carcinomas. This study aims to verify the relationship between p63 expression and several clinicopathological features and tumor markers of clinical significance in breast pathology including key regulators of the cell cycle, oncogenes, apoptosis-related proteins, metalloproteinases and their inhibitors. Immunohistochemistry with 27 primary antibodies was performed in 100 formalin-fixed paraffin-embedded samples of invasive ductal carcinomas. p63-positive cells were found in 16% of carcinomas. p63-positive carcinomas were poorly differentiated, hormone receptor-negative neoplasms with a high proliferation rate. p63 also correlated with advanced pathological stage, tumor size, and the expression of human telomerase reverse transcriptase (hTERT), tissue inhibitor of matrix metalloproteinase 1 (TIMP1) and vascular endothelial growth factor (VEGF). The expression of TIMP1 suggests that the anti-proteolytic stimuli may be preponderant in p63-positive carcinomas. hTERT activity is associated with nodal metastases and cellular proliferation. VEGF regulates angiogenesis, which is also a fundamental event in the process of tumor growth and metastatic dissemination. Thus, the differential regulation of hTERT and VEGF in p63-positive breast carcinomas may contribute to the clinically more aggressive behavior of these neoplasms.

Reduced myofilament component in primary Sjögren's syndrome salivary gland myoepithelial cells

Primary Sjögren's syndrome (pSS) is a solitary poorly understood autoimmune inflammatory disease by involvement of the salivary and lacrimal glands resulting in dry mouth and dry eyes. Myoepithelial cells (MECs) are cells knowing for its hybrid epithelial and mesenchymal phenotype that are important components of the salivary gland (SGs) structure aiding the expulsion of saliva from acinar lobules. In this study we investigate possible alteration in the myofilament component of MECs in SGs specimens obtained from pSS patients in comparison with healthy subjects, to evaluate MECs hypothetical involvement in the pathogenesis of pSS. The expression of alpha-smooth muscle actin (α-SMA) and p63, as MECs markers, was evaluated in bioptic specimens from pSS and healthy labial SGs through immunohistochemistry and immunofluorescence analyses; the distribution of MECs markers was quantified using Aperio ScanScope and ImageScope software to provide quantitative assessments of staining levels. Our observations demonstrated that p63 nuclear labeling in pSS MECs is preserved whereas α-SMA cytoplasmic staining is strongly and significantly reduced when compared with healthy SGs; the digital images analysis quantification of the expression of labeled α-SMA and p63 protein in the healthy and pSS MECs salivary tissues, led to results suggesting a loss of mechanical support for acini and ducts in pSS, correlated, probably, with the reduction of salivary flow that features one important aspect of pSS disease.

Obesity reversibly depletes the basal cell population and enhances mammary epithelial cell estrogen receptor alpha expression and progenitor activity

Background

Obesity is correlated with an increased risk for developing postmenopausal breast cancer. Since obesity rates continue to rise worldwide, it is important to understand how the obese microenvironment influences normal mammary tissue to increase breast cancer risk. We hypothesized that obesity increases the proportion of luminal progenitor cells, which are thought to be the cells of origin for the most common types of breast cancer, potentially leading to an increased risk for breast cancer.

Methods

To study the obese microenvironment within the mammary gland, we used a high-fat diet mouse model of obesity and human breast tissue from reduction mammoplasty surgery. We identified changes in breast epithelial cell populations using flow cytometry for cell surface markers, in vitro functional assays and expression of markers on breast tissue sections.

Results

In both obese female mice and women, mammary epithelial cell populations demonstrated significant decreases in basal/myoepithelial cells, using either flow cytometry or cell-type-specific markers (SMA and p63). Estrogen receptor alpha (ERα) expression was significantly increased in luminal cells in obese mammary tissue, compared with control mice or breast tissue from lean women. Functional assays demonstrated significantly enhanced mammary epithelial progenitor activity in obese mammary epithelial cells and elevated numbers of ERα-positive epithelial cells that were co-labeled with markers of proliferation. Weight loss in a group of obese mice reversed increases in progenitor activity and ERα expression observed in obese mammary tissue.

Conclusions

Obesity enhances ERα-positive epithelial cells, reduces the number of basal/myoepithelial cells, and increases stem/progenitor activity within normal mammary tissue in both women and female mice. These changes in epithelial cell populations induced by obesity are reversible with weight loss. Our findings support further studies to examine how obesity-induced changes in stem/progenitor cells impact breast tumor incidence and histologic tumor types.

Electronic supplementary material

The online version of this article (doi:10.1186/s13058-017-0921-7) contains supplementary material, which is available to authorized users.

Quantitative diagnosis of breast tumors by morphometric classification of microenvironmental myoepithelial cells using a machine learning approach

Machine learning systems have recently received increased attention for their broad applications in several fields. In this study, we show for the first time that histological types of breast tumors can be classified using subtle morphological differences of microenvironmental myoepithelial cell nuclei without any direct information about neoplastic tumor cells. We quantitatively measured 11661 nuclei on the four histological types: normal cases, usual ductal hyperplasia and low/high grade ductal carcinoma in situ (DCIS). Using a machine learning system, we succeeded in classifying the four histological types with 90.9% accuracy. Electron microscopy observations suggested that the activity of typical myoepithelial cells in DCIS was lowered. Through these observations as well as meta-analytic database analyses, we developed a paracrine cross-talk-based biological mechanism of DCIS progressing to invasive cancer. Our observations support novel approaches in clinical computational diagnostics as well as in therapy development against progression.

ΔNp63α expression induces loss of cell adhesion in triple-negative breast cancer cells

Background

p63, a member of the p53 protein family, plays key roles in epithelial development and carcinogenesis. In breast cancer, p63 expression has been found predominantly in basal-A (epithelial-type) triple-negative breast carcinomas (TNBC). To investigate the functional role of p63 in basal-A TNBC, we created MDA-MB-468 cell lines with inducible expression of the two major N-terminal p63 isoforms, TAp63α and ∆Np63α.

Results

TAp63α did not have significant effect on gene expression profile and cell phenotype, whilst the main effect of ΔNp63α was reduction of cell adhesion. Gene expression profiling revealed genes involved in cell adhesion and migration whose expression relies on overexpression of ΔNp63α. Reduced cell adhesion also led to decreased cell proliferation in vitro and in vivo. Similar data were obtained in another basal-A cell line, BT-20, but not in BT-549 basal-B (mesenchymal-like) TNBC cells.

Conclusions

In basal-A TNBC cells, ∆Np63α has much stronger effects on gene expression than TAp63α. Although p63 is mentioned mostly in connection with breast cell differentiation and stem cell regulation, we showed that a major effect of p63 is regulation of cell adhesion, a process important in metastasis and invasion of tumour cells. That this effect is not seen in mesenchymal-type TNBC cells suggests lineage-dependent functions, mirroring the expression of ∆Np63α in primary human breast cancers.

Electronic supplementary material

The online version of this article (doi:10.1186/s12885-016-2808-x) contains supplementary material, which is available to authorized users.

Repression of p63 and induction of EMT by mutant Ras in mammary epithelial cells

The p53-related transcription factor p63 is required for maintenance of epithelial cell differentiation. We found that activated forms of the Harvey Rat Sarcoma Virus GTPase (H-RAS) and phosphatidylinositol-4,5-bisphosphate 3-kinase catalytic subunit alpha (PIK3CA) oncogenes strongly repress expression of ∆Np63α, the predominant p63 isoform in basal mammary epithelial cells. This regulation occurs at the transcriptional level, and a short region of the ∆Np63 promoter is sufficient for repression induced by H-RasV12. The suppression of ∆Np63α expression by these oncogenes concomitantly leads to an epithelial-to-mesenchymal transition (EMT). In addition, the depletion of ∆Np63α alone is sufficient to induce EMT. Both H-RasV12 expression and ∆Np63α depletion induce individual cell invasion in a 3D collagen gel in vitro system, thereby demonstrating how Ras can drive the mammary epithelial cell state toward greater invasive ability. Together, these results suggest a pathway by which RAS and PIK3CA oncogenes induce EMT through regulation of ∆Np63α.

Expression of p40 (∆Np63) protein in meningiomas, an unexpected finding: immunohistochemical study and evaluation of its possible prognostic role

According to the 2007 WHO (World Health Organization) Classification, meningiomas are divided into three grades of malignancy, with different recurrence rate, based exclusively on histopathological parameters. Loss/reduction of PgR (Progesterone Receptor) expression and increased Ki67 L.I. (Labeling Index) have been proven as possible prognostic factors able to predict the relapse of the disease. However, they sometimes result unreliable, especially when discordant. p40 is the short form of the p53 homologue gene p63, also named ∆Np63, and its antibody has recently been introduced as a highly specific diagnostic marker of the squamous cell carcinoma of the lung. Nevertheless its expression has been found in many other unconventional sites (e.g. placenta, urotheluim, etc). Herein we assessed the immuno-expression of p40 protein in a series of 72 meningiomas (35 grade I and 37 grade II) and analyzed its correlation with clinicopathological parameters, overall survival and recurrence free interval. We found that a high p40 score correlated with high histological grade, presence of recurrence, increased Ki67 L.I. and loss/reduction of PgR signal. Moreover, a higher expression of p40 was shown to be a significant prognostic factor for the development of recurrences and resulted a prognostic independent variable in multivariate analysis. Overall, for the first time, we investigated the expression of p40 protein in meningiomas and explored its usefulness as prognostic marker in addition to PgR and Ki67 L.I.

The Expression of p63 and Cytokeratin 5 in Mixed Tumors of the Canine Mammary Gland Provides New Insights into the Histogenesis of These Neoplasms

Cytokeratin 5 and p63 have been described as basal and myoepithelial cell markers in human breast. Mixed tumors of the canine mammary gland have been associated with a myoepithelial origin. Cytokeratin 5 expression has not been evaluated in these tumors. We investigated the relation between cytokeratin 5 and p63 double-immunohistochemical expression in 23 mixed tumors of the canine mammary gland (10 benign mixed tumors and 13 carcinomas arising from benign mixed tumors) and their origin. Cytokeratin 5 and p63 co-expression was observed in myoepithelial cells of benign mixed tumors, as well as in squamous differentiation of carcinoma arising from benign mixed tumors. Though a few interstitial spindle cells of the mesenchymal components expressed both p63 and cytokeratin 5, the basal epithelial cells were labeled only by cytokeratin 5. The co-expression of p63 and cytokeratin 5 in myoepithelial cells and squamous differentiation suggest that, like in human breast, cytokeratin 5 can also be considered a myoepithelial- and squamous-cell differentiating marker in canine tumors. The presence of some interstitial spindle cells stained for p63 and cytokeratin 5 might be associated with a myoepithelial origin of the mesenchymal component of mixed tumors of the canine mammary gland. Moreover, contrary to p63, basal epithelial cells were labeled by cytokeratin 5, indicating that cytokeratin 5 may not represent an exclusive myoepithelial cell marker but also a basal epithelial cell marker in canine mixed tumors. According to these data, basal epithelial cells may be related to the origin of the epithelial component of mixed tumors of the canine mammary gland.

Prognostic factors in the myoepithelial-like spindle cell type of metaplastic breast cancer

Metaplastic breast carcinoma (MBC) comprises a heterogeneous group of tumors with difficult to predict biological behavior. A subset of MBC, characterized by spindle-shaped tumor cells with a myoepithelial-like immunophenotype, was entered into a retrospective study (n = 42, median follow-up time 43 months). Molecular parameters (DNA sequences of mutation hot spots in AKT1, ALK, APC, BRAF, CDH1, CTNNB1, EGFR, ERBB2, FBXW7, FGFR2, FOXL2, GNAQ, GNAS, KIT, KRAS, MAP2K1, MET, MSH6, NRAS, PDGFRA, PIK3CA, PTEN, SF3B1, SMAD4, SRC, SRSF2, STK11, TP53, and U2AF1; copy numbers for EGFR, c-myc, FGFR, PLAG, c-met) were assessed. None of the patients had axillary lymph node involvement. In 13 cases, local recurrence developed after surgery (30.9 %). Distant metastasis occurred in seven patients (17 %; four after local recurrence). The most frequent genetic alteration was PIK3CA mutation (50 % of cases). None of the pathological parameters (size, grade, stage, Ki-67 labeling index) was significantly associated with disease-free survival (DFS) or overall survival (OS). PIK3CA mutation, especially the H1047R type, tended to adversely affect OS. Type of resection (mastectomy vs. breast-conserving therapy, width of margins) or adjuvant radiotherapy had no influence on DFS or OS, whereas in the group treated with radio-/chemotherapy, no local recurrence or metastasis and no death occurred. We conclude that the spindle cell type of MBC with myoepithelial features exhibits a higher frequency of PIK3CA mutation than other types of metaplastic or basal-like breast cancer and may benefit from combined radio-/chemotherapy. Classical pathological parameters are not helpful in identifying the high-risk tumors among this subgroup of MBC.

Novel Use for DOG1 in Discriminating Breast Invasive Carcinoma from Noninvasive Breast Lesions

Aims. DOG1 has proven to be a useful marker of gastrointestinal stromal tumors (GISTs). Recently, DOG1 expression has also been reported in some non-GIST malignant tumors, but the details related to DOG1 expression in breast tissue remain unclear. The aim of this study was to detect the expression of DOG1 in the human breast and to evaluate the feasibility of using DOG1 to discriminate between invasive breast carcinoma and noninvasive breast lesions. Methods and Results. A total of 210 cases, including both invasive and noninvasive breast lesions, were collected to assess DOG1 expression immunohistochemically. DOG1 expression was consistently positive in breast myoepithelial cells (MECs), which was similar to the results obtained for three other MEC markers: calponin, smooth muscle myosin heavy chain (SMMHC), and P63 (P > 0.05 in all). Importantly, DOG1 was useful in discriminating invasive breast carcinoma from noninvasive breast lesions (P < 0.05). Conclusions. DOG1 is a useful marker of breast MECs, and adding DOG1 to the MEC identification panel will provide more sophisticated information when diagnosing uncertain cases in the breast.

An oncogenic MYB feedback loop drives alternate cell fates in adenoid cystic carcinoma

Translocation events are frequent in cancer and may create chimeric fusions or ‘regulatory rearrangements’ that drive oncogene overexpression. Here we identify super-enhancer translocations that drive overexpression of the oncogenic transcription factor MYB as a recurrent theme in adenoid cystic carcinoma (ACC). Whole-genome sequencing data and chromatin maps reveal distinct chromosomal rearrangements that juxtapose super-enhancers to the MYB locus. Chromosome conformation capture confirms that the translocated enhancers interact with the MYB promoter. Remarkably, MYB protein binds to the translocated enhancers, creating a positive feedback loop that sustains its expression. MYB also binds enhancers that drive different regulatory programs in alternate cell lineages in ACC, cooperating with TP63 in myoepithelial cells and a Notch program in luminal epithelial cells. Bromodomain inhibitors slow tumor growth in ACC primagraft models in vivo. Thus, our study identifies super-enhancer translocations that drive MYB expression and provides insight into downstream MYB functions in the alternate ACC lineages.

ΔNp63 regulates cell proliferation, differentiation, adhesion, and migration in the BL2 subtype of basal-like breast cancer

Triple-negative breast cancers (TNBC) comprise a heterogeneous subgroup of tumors with a generally poor prognosis. Subclassification of TNBC based on genomic analyses shows that basal-like TNBCs, specifically the basal A or BL2 subtype, are characterized by the expression of ΔNp63, a transcription factor that has been attributed a variety of roles in the regulation of proliferation, differentiation, and cell survival. To investigate the role(s) of p63 in basal-like breast cancers, we used HCC1806 cells that are classified as basal A/BL2. We show that these cells endogenously express p63, mainly as the ΔNp63α isoform. TP63 gene knockout by CRISPR resulted in viable cells that proliferate more slowly and adhere less tightly, with an increased rate of migration. Analysis of adhesion-related gene expression revealed a complex set of alterations in p63-depleted cells, with both increased and decreased adhesion molecules and adhesion substrates compared to parental cells expressing p63. Examination of the phenotype of these cells indicated that endogenous p63 is required to suppress the expression of luminal markers and maintain the basal epithelial phenotype, with increased levels of both CK8 and CK18 and a reduction in N-cadherin levels in cells lacking p63. On the other hand, the level of CK5 was not decreased and ER was not increased, indicating that p63 loss is insufficient to induce full luminal-type differentiation. Taken together, these data demonstrate that p63 exerts multiple pro-oncogenic effects on cell differentiation, proliferation and adhesion in basal-like breast cancers.