Cutaneous Human Papillomaviruses and the Risk of Keratinocyte Carcinomas

Cutaneous human papillomavirus (cuHPV) infections may be novel targets for skin cancer prevention and treatment, but critical information regarding the development of virus-positive skin cancers following cuHPV infection has been lacking. In this study, baseline cuHPV infection was measured by serology and viral DNA detection in eyebrow hairs (EBH) and forearm skin swabs (SSW) among 1,008 individuals undergoing routine skin cancer screening exams and followed for incidence of basal cell carcinoma (BCC) and cutaneous squamous cell carcinoma (cuSCC). Baseline β-HPV detection, particularly in SSW, significantly predicted cuSCC (HR = 4.32; 95% confidence interval, 1.00-18.66), whereas serologic evidence of past β-HPV infection was not associated with cuSCC. Less than 5% of baseline β-HPV types detected in SSW were present in subsequent cuSCC tumors, and cuHPV detected in SSW with higher mean fluorescence intensity values were more likely to be present in cuSCC compared with those with lower levels (P < 0.001). β-HPV-positive cuSCC occurred more often in areas of highly sun-damaged skin than did β-HPV-negative cuSCC. Overall, no clear patterns were observed between baseline β-HPV detection and subsequent development of BCC, or between baseline γ-HPV detection and either cuSCC or BCC. Collectively, these results demonstrate that β-HPV detection in SSW is a significant predictor of cuSCC risk, although evidence suggests only a small subset of cuSCC is etiologically linked to β-HPV infection. SIGNIFICANCE: β-HPV positivity may be a useful biomarker for identifying individuals who could benefit from increased screening or novel cutaneous squamous cell carcinoma prevention strategies.

The ECM Modulator ITIH5 Affects Cell Adhesion, Motility and Chemotherapeutic Response of Basal/Squamous-Like (BASQ) Bladder Cancer Cells

This study aims at characterizing the role of the putative tumor suppressor ITIH5 in basal-type bladder cancers (BLCA). By sub-classifying TCGA BLCA data, we revealed predominant loss of ITIH5 expression in the basal/squamous-like (BASQ) subtype. ITIH5 expression inversely correlated with basal-type makers such as KRT6A and CD44. Interestingly, Kaplan–Meier analyses showed longer recurrence-free survival in combination with strong CD44 expression, which is thought to mediate ITIH-hyaluronan (HA) binding functions. In vitro, stable ITIH5 overexpression in two basal-type BLCA cell lines showing differential CD44 expression levels, i.e., with (SCaBER) and without squamous features (HT1376), demonstrated clear inhibition of cell and colony growth of BASQ-type SCaBER cells. ITIH5 further enhanced HA-associated cell-matrix attachment, indicated by altered size and number of focal adhesion sites resulting in reduced cell migration capacities. Transcriptomic analyses revealed enrichment of pathways and processes involved in ECM organization, differentiation and cell signaling. Finally, we provide evidence that ITIH5 increase sensitivity of SCaBER cells to chemotherapeutical agents (cisplatin and gemcitabine), whereas responsiveness of HT1376 cells was not affected by ITIH5 expression. Thus, we gain further insights into the putative role of ITIH5 as tumor suppressor highlighting an impact on drug response potentially via the HA-CD44 axis in BASQ-type BLCA.

False-Positive Uptake of 131I From Basal Cell Papilloma in a Patient With Metastatic Papillary Thyroid Cancer

ABSTRACT

A 64-year-old woman with metastatic papillary thyroid cancer underwent a total thyroidectomy followed by 2 courses of 131I therapy. The posttherapeutic whole-body scan after the second dose of 131I therapy showed multifocal bone metastasis. In addition, there is focal abnormal intense radiotracer uptake at the right inguinal region. SPECT/CT revealed that this abnormal focal radioactivity was from a superficial skin lesion. Further physical examination revealed a raised, approximately 1-cm, irregular grayish-brown lesion on the right groin skin. Histopathological examination confirmed the diagnosis of basal cell papilloma (seborrheic keratosis).

Immunity drives TET1 regulation in cancer through NF-κB

Ten-eleven translocation enzymes (TET1, TET2, and TET3), which induce DNA demethylation and gene regulation by converting 5-methylcytosine (5mC) to 5-hydroxymethylcytosine (5hmC), are often down-regulated in cancer. We uncover, in basal-like breast cancer (BLBC), genome-wide 5hmC changes related to TET1 regulation. We further demonstrate that TET1 repression is associated with high expression of immune markers and high infiltration by immune cells. We identify in BLBC tissues an anticorrelation between TET1 expression and the major immunoregulator family nuclear factor κB (NF-κB). In vitro and in mice, TET1 is down-regulated in breast cancer cells upon NF-κB activation through binding of p65 to its consensus sequence in the TET1 promoter. We lastly show that these findings extend to other cancer types, including melanoma, lung, and thyroid cancers. Together, our data suggest a novel mode of regulation for TET1 in cancer and highlight a new paradigm in which the immune system can influence cancer cell epigenetics.

SALL4 - KHDRBS3 network enhances stemness by modulating CD44 splicing in basal-like breast cancer

Understanding the mechanism by which cancer cells enhance stemness facilitates cancer therapies. Here, we revealed that a stem cell transcription factor, SALL4, functions to enhance stemness in basal-like breast cancer cells. We used shRNA-mediated knockdown and gene overexpression systems to analyze gene functions. To evaluate stemness, we performed a sphere formation assay. In SALL4 knockdown cells, the sphere formation ability was reduced, indicating that SALL4 enhances stemness. CD44 is a membrane protein and is known as a stemness factor in cancer. CD44 splicing variants are involved in cancer stemness. We discovered that SALL4 modulates CD44 alternative splicing through the upregulation of KHDRBS3, a splicing factor for CD44. We cloned the KHDRBS3-regulated CD44 splicing isoform (CD44v), which lacks exons 8 and 9. CD44v overexpression prevented a reduction in the sphere formation ability by KHDRBS3 knockdown, indicating that CD44v is positively involved in cancer stemness. In addition, CD44v enhanced anoikis resistance under the control of the SALL4 - KHDRBS3 network. Basal-like breast cancer is an aggressive subtype among breast cancers, and there is no effective therapy so far. Our findings provide molecular targets for basal-like breast cancer therapy. In the future, this study may contribute to the establishment of drugs targeting cancer stemness.

ASCT2/SLC1A5 controls glutamine uptake and tumour growth in triple-negative basal-like breast cancer

Alanine, serine, cysteine-preferring transporter 2 (ASCT2; SLC1A5) mediates uptake of glutamine, a conditionally essential amino acid in rapidly proliferating tumour cells. Uptake of glutamine and subsequent glutaminolysis is critical for activation of the mTORC1 nutrient-sensing pathway, which regulates cell growth and protein translation in cancer cells. This is of particular interest in breast cancer, as glutamine dependence is increased in high-risk breast cancer subtypes. Pharmacological inhibitors of ASCT2-mediated transport significantly reduced glutamine uptake in human breast cancer cell lines, leading to the suppression of mTORC1 signalling, cell growth and cell cycle progression. Notably, these effects were subtype-dependent, with ASCT2 transport critical only for triple-negative (TN) basal-like breast cancer cell growth compared with minimal effects in luminal breast cancer cells. Both stable and inducible shRNA-mediated ASCT2 knockdown confirmed that inhibiting ASCT2 function was sufficient to prevent cellular proliferation and induce rapid cell death in TN basal-like breast cancer cells, but not in luminal cells. Using a bioluminescent orthotopic xenograft mouse model, ASCT2 expression was then shown to be necessary for both successful engraftment and growth of HCC1806 TN breast cancer cells in vivo. Lower tumoral expression of ASCT2 conferred a significant survival advantage in xenografted mice. These responses remained intact in primary breast cancers, where gene expression analysis showed high expression of ASCT2 and glutamine metabolism-related genes, including GLUL and GLS, in a cohort of 90 TN breast cancer patients, as well as correlations with the transcriptional regulators, MYC and ATF4. This study provides preclinical evidence for the feasibility of novel therapies exploiting ASCT2 transporter activity in breast cancer, particularly in the high-risk basal-like subgroup of TN breast cancer where there is not only high expression of ASCT2, but also a marked reliance on its activity for sustained cellular proliferation.

The antitumorigenic function of EGFR in metastatic breast cancer is regulated by expression of Mig6

Numerous studies by our lab and others demonstrate that epidermal growth factor receptor (EGFR) plays critical roles in primary breast cancer (BC) initiation, growth and dissemination. However, clinical trials targeting EGFR function in BC have lead to disappointing results. In the current study we sought to identify the mechanisms responsible for this disparity by investigating the function of EGFR across the continuum of the metastatic cascade. We previously established that overexpression of EGFR is sufficient for formation of in situ primary tumors by otherwise nontransformed murine mammary gland cells. Induction of epithelial-mesenchymal transition (EMT) is sufficient to drive the metastasis of these EGFR-transformed tumors. Examining growth factor receptor expression across this and other models revealed a potent downregulation of EGFR through metastatic progression. Consistent with diminution of EGFR following EMT and metastasis EGF stimulation changes from a proliferative to an apoptotic response in in situ versus metastatic tumor cells, respectively. Furthermore, overexpression of EGFR in metastatic MDA-MB-231 BC cells promoted their antitumorigenic response to EGF in three dimensional (3D) metastatic outgrowth assays. In line with the paradoxical function of EGFR through EMT and metastasis we demonstrate that the EGFR inhibitory molecule, Mitogen Induced Gene-6 (Mig6), is tumor suppressive in in situ tumor cells. However, Mig6 expression is absolutely required for prevention of apoptosis and ultimate metastasis of MDA-MB-231 cells. Further understanding of the paradoxical function of EGFR between primary and metastatic tumors will be essential for application of its targeted molecular therapies in BC.

DNA Methylation Affects the SP1-regulated Transcription of FOXF2 in Breast Cancer Cells

FOXF2 (forkhead box F2) is a mesenchyme-specific transcription factor that plays a critical role in tissue homeostasis through the maintenance of epithelial polarity. In a previous study, we demonstrated that FOXF2 is specifically expressed in basal-like breast cancer (BLBC) cells and functions as an epithelial-mesenchymal transition suppressor. FOXF2 deficiency enhances the metastatic ability of BLBC cells through activation of the epithelial-mesenchymal transition program, but reduces cell proliferation. In this study, we demonstrate that CpG island methylation of the FOXF2 proximal promoter region is involved in the regulatory mechanism of the subtype-specific expression of FOXF2 in breast cancer cells. DNMT1, DNMT3A, and DNMT3B commonly or individually contributed to this DNA methylation in different breast cancer cells. SP1 regulated the transcriptional activity of FOXF2 through direct binding to the proximal promoter region, whereas this binding was abrogated through DNA methylation. FOXF2 mediated the SP1-regulated suppression of progression and promotion of proliferation of non-methylated BLBC cells. Thus, we conclude that the subtype-specific expression and function of FOXF2 in breast cancer cells are regulated through the combined effects of DNA methylation and SP1 transcriptional regulation.

Novel role of Engrailed 1 as a prosurvival transcription factor in basal-like breast cancer and engineering of interference peptides block its oncogenic function

Basal-like breast tumors are aggressive cancers associated with high proliferation and metastasis. Chemotherapy is currently the only treatment option; however, resistance often occurs resulting in recurrence and patient death. Some extremely aggressive cancers are also associated with hypoxia, inflammation and high leukocyte infiltration. Herein, we discovered that the neural-specific transcription factor, Engrailed 1 (EN1), is exclusively overexpressed in these tumors. Short hairpin RNA (shRNA)-mediated knockdown of EN1 triggered potent and selective cell death. In contrast, ectopic overexpression of EN1 in normal cells activated survival pathways and conferred resistance to chemotherapeutic agents. Exogenous expression of EN1 cDNA reprogrammed the breast epithelial cells toward a long-lived, neural-like phenotype displaying dopaminergic markers. Gene expression microarrays demonstrated that the EN1 cDNA altered transcription of a high number of inflammatory molecules, notably chemokines and chemokine receptors, which could mediate prosurvival pathways. To block EN1 function, we engineered synthetic interference peptides (iPeps) comprising the EN1-specific sequences that mediate essential protein-protein interactions necessary for EN1 function and an N-terminal cell-penetrating peptide/nuclear localization sequence. These EN1-iPeps rapidly mediated a strong apoptotic response in tumor cells overexpressing EN1, with no toxicity to normal or non EN1-expressing cells. Delivery of EN1-iPeps into basal-like cancer cells significantly decreased the fifty percent inhibitory concentrations (IC50) of chemotherapeutic drugs routinely used to treat breast cancer. Lastly, matrix-assisted laser desorption/ionization-time of flight mass spectrometry and immunoprecipitation assays demonstrated that EN1-iPeps captured targets involved in transcriptional and post-transcriptional regulation. Importantly, the EN1-iPeps bound the glutamyl-prolyl tRNA synthetase (EPRS) target, which has been associated with the transcript-specific translational control of inflammatory proteins and activation of amino-acid stress pathways. This work unveils EN1 as an activator of intrinsic inflammatory pathways associated with prosurvival in basal-like breast cancer. We further build upon these results and describe the engineering of iPeps targeting EN1 (EN1-iPeps) as a novel and selective therapeutic strategy to combat these lethal forms of breast cancer.

The co-factor of LIM domains (CLIM/LDB/NLI) maintains basal mammary epithelial stem cells and promotes breast tumorigenesis

Mammary gland branching morphogenesis and ductal homeostasis relies on mammary stem cell function for the maintenance of basal and luminal cell compartments. The mechanisms of transcriptional regulation of the basal cell compartment are currently unknown. We explored these mechanisms in the basal cell compartment and identified the Co-factor of LIM domains (CLIM/LDB/NLI) as a transcriptional regulator that maintains these cells. Clims act within the basal cell compartment to promote branching morphogenesis by maintaining the number and proliferative potential of basal mammary epithelial stem cells. Clim2, in a complex with LMO4, supports mammary stem cells by directly targeting the Fgfr2 promoter in basal cells to increase its expression. Strikingly, Clims also coordinate basal-specific transcriptional programs to preserve luminal cell identity. These basal-derived cues inhibit epidermis-like differentiation of the luminal cell compartment and enhance the expression of luminal cell-specific oncogenes ErbB2 and ErbB3. Consistently, basal-expressed Clims promote the initiation and progression of breast cancer in the MMTV-PyMT tumor model, and the Clim-regulated branching morphogenesis gene network is a prognostic indicator of poor breast cancer outcome in humans.

Recent advancements in mammary gland biology demonstrate conflicting models in maintenance of basal and luminal cell compartments by either unipotent or bipotent mammary stem cells. However, the molecular mechanisms underlying control of the basal cell compartment, including stem cells, remain poorly understood. Here we explore the currently unknown transcriptional mechanisms of basal stem cell (BSC) maintenance, in addition to addressing the role of the basal cell compartment in preserving luminal cell fate and promoting development of human breast tumors of luminal origin. We discover a novel function for the Co-factor of LIM domains (Clim) transcriptional regulator in promoting mammary gland branching morphogenesis and breast tumorigenesis through maintenance of the basal stem cell population. The transcriptional networks coordinated by Clims in basal mammary epithelial cells also preserve the identity of luminal epithelial cells, demonstrating a crosstalk between these two cellular compartments. Furthermore, we correlate developmental gene expression data with human breast cancer to investigate the role of developmental pathways during the initiation and progression of breast cancer. The gene regulatory networks identified during development, including those specifically coordinated by Clims, correlate with breast cancer patient outcome, suggesting these genes play an important role in the progression of breast cancer.

Sumoylation pathway is required to maintain the basal breast cancer subtype

The TFAP2C/AP-2γ transcription factor regulates luminal breast cancer genes, and loss of TFAP2C induces epithelial-mesenchymal transition. By contrast, the highly homologous family member, TFAP2A, lacks transcriptional activity at luminal gene promoters. A detailed structure-function analysis identified that sumoylation of TFAP2A blocks its ability to induce the expression of luminal genes. Disruption of the sumoylation pathway by knockdown of sumoylation enzymes, mutation of the SUMO-target lysine of TFAP2A, or treatment with sumoylation inhibitors induced a basal-to-luminal transition, which was dependent on TFAP2A. Sumoylation inhibitors cleared the CD44(+/hi)/CD24(-/low) cell population characterizing basal cancers and inhibited tumor outgrowth of basal cancer xenografts. These findings establish a critical role for sumoylation in regulating the transcriptional mechanisms that maintain the basal cancer phenotype.

Prognostic B-cell signatures using mRNA-seq in patients with subtype-specific breast and ovarian cancer

PURPOSE

Lymphocytic infiltration of tumors predicts improved survival in patients with breast cancer. Previous studies have suggested that this survival benefit is confined predominantly to the basal-like subtype. Immune infiltration in ovarian tumors is also associated with improved prognosis. Currently, it is unclear what aspects of the immune response mediate this improved outcome.

EXPERIMENTAL DESIGN

Using The Cancer Genome Atlas mRNA-seq data and a large microarray dataset, we evaluated adaptive immune gene expression by genomic subtype in breast and ovarian cancer. To investigate B-cells observed to be prognostic within specific subtypes, we developed methods to analyze B-cell population diversity and degree of somatic hypermutation (SHM) from B-cell receptor (BCR) sequences in mRNA-seq data.

RESULTS

Improved metastasis-free/progression-free survival was correlated with B-cell gene expression signatures, which were restricted mainly to the basal-like and HER2-enriched breast cancer subtypes and the immunoreactive ovarian cancer subtype. Consistent with a restricted epitope-driven response, a subset of basal-like and HER2-enriched breast tumors and immunoreactive ovarian tumors showed high expression of a low-diversity population of BCR gene segments. More BCR segments showed improved prognosis with increased expression in basal-like breast tumors and immunoreactive ovarian tumors compared with other subtypes. Basal-like and HER2-enriched tumors exhibited more BCR sequence variants in regions consistent with SHM.

CONCLUSION

Taken together, these data suggest the presence of a productive and potentially restricted antitumor B-cell response in basal-like breast and immunoreactive ovarian cancers. Immunomodulatory therapies that support B-cell responses may be a promising therapeutic approach to targeting these B-cell infiltrated tumors.

[New aspects of the pathogenesis and classification of basal-like breast carcinoma]

New approaches to the molecular classification of breast cancer are considered. Particular emphasis is placed on its basal-like type that belongs to the most aggressive and prognostically unfavorable forms of tumor. The origin of this type of breast cancer is the subject of intense debate in the scientific community. There are three basic theories that basal-like breast carcinoma may arise from the stem or myoepithelial cells and through dedifferentiation via epithelial-mesenchymal transformation. The theory of its origin from stem/progenitor cells is most valid and proven.

Combined targeting of mTOR and AKT is an effective strategy for basal-like breast cancer in patient-derived xenograft models

Basal-like breast cancer is an aggressive disease for which targeted therapies are lacking. Recent studies showed that basal-like breast cancer is frequently associated with an increased activity of the phosphatidylinositol 3-kinase (PI3K) pathway, which is critical for cell growth, survival, and angiogenesis. To investigate the therapeutic potential of PI3K pathway inhibition in the treatment of basal-like breast cancer, we evaluated the antitumor effect of the mTOR inhibitor MK-8669 and AKT inhibitor MK-2206 in WU-BC4 and WU-BC5, two patient-derived xenograft models of basal-like breast cancer. Both models showed high levels of AKT phosphorylation and loss of PTEN expression. We observed a synergistic effect of MK-8669 and MK-2206 on tumor growth and cell proliferation in vivo. In addition, MK-8669 and MK-2206 inhibited angiogenesis as determined by CD31 immunohistochemistry. Biomarker studies indicated that treatment with MK-2206 inhibited AKT activation induced by MK-8669. To evaluate the effect of loss of PTEN on tumor cell sensitivity to PI3K pathway inhibition, we knocked down PTEN in WU-BC3, a basal-like breast cancer cell line with intact PTEN. Compared with control (GFP) knockdown, PTEN knockdown led to a more dramatic reduction in cell proliferation and tumor growth inhibition in response to MK-8669 and MK-2206 both in vitro and in vivo. Furthermore, a synergistic effect of these two agents on tumor volume was observed in WU-BC3 with PTEN knockdown. Our results provide a preclinical rationale for future clinical investigation of this combination in basal-like breast cancer with loss of PTEN.

FOXA1 represses the molecular phenotype of basal breast cancer cells

Breast cancer is a heterogeneous disease that comprises multiple subtypes. Luminal subtype tumors confer a more favorable patient prognosis, which is, in part, attributed to estrogen receptor (ER)-α positivity and antihormone responsiveness. Expression of the forkhead box transcription factor, FOXA1, similarly correlates with the luminal subtype and patient survival, but is also present in a subset of ER-negative tumors. FOXA1 is also consistently expressed in luminal breast cancer cell lines even in the absence of ER. In contrast, breast cancer cell lines representing the basal subtype do not express FOXA1. To delineate an ER-independent role for FOXA1 in maintaining the luminal phenotype, and hence a more favorable prognosis, we performed expression microarray analyses on FOXA1-positive and ER-positive (MCF7, T47D), or FOXA1-positive and ER-negative (MDA-MB-453, SKBR3) luminal cell lines in the presence or absence of transient FOXA1 silencing. This resulted in three FOXA1 transcriptomes: (1) a luminal signature (consistent across cell lines), (2) an ER-positive signature (restricted to MCF7 and T47D) and (3) an ER-negative signature (restricted to MDA-MB-453 and SKBR3). Gene set enrichment analyses revealed FOXA1 silencing causes a partial transcriptome shift from luminal to basal gene expression signatures. FOXA1 binds to a subset of both luminal and basal genes within luminal breast cancer cells, and loss of FOXA1 increases enhancer RNA transcription for a representative basal gene (CD58). These data suggest FOXA1 directly represses a subset of basal signature genes. Functionally, FOXA1 silencing increases migration and invasion of luminal cancer cells, both of which are characteristics of basal subtype cells. We conclude FOXA1 controls plasticity between basal and luminal breast cancer cells, not only by inducing luminal genes but also by repressing the basal phenotype, and thus aggressiveness. Although it has been proposed that FOXA1-targeting agents may be useful for treating luminal tumors, these data suggest that this approach may promote transitions toward more aggressive cancers.

Lack of expression of the proteins GMPR2 and PPARα are associated with the basal phenotype and patient outcome in breast cancer

Basal-like tumours (BP) are a poor prognostic class of breast cancer but remain a biologically and clinically heterogeneous group. We have previously identified two novel genes PPARα (positive) and GMPR2 (negative) whose expression was significantly associated with BP at the transcriptome level. In this study, using a large and well-characterised series of operable invasive breast carcinomas (1,043 cases) prepared as TMAs, we assessed these targets at the protein level using immunohistochemistry and investigated associations with clinicopathological variables and patient outcome.

RESULTS

Lack of PPARα and GMPR2 protein expression was associated with BP, as defined by the expression of cytokeratin (CK) 5/6 and/or CK14, (p = 0.023, p = 0.001, respectively) or as triple-negative (ER-, PR-, HER2-) phenotype (p < 0.001 for both proteins). Positive expression of both markers was associated ER and PR positive status (p < 0.05) and with the good Nottingham Prognostic Index group (p = 0.012, p < 0.001, respectively). Univariate survival analysis showed an association between lack of expression of PPARα and GMPR2 and poor outcome in terms of shorter disease-free survival and shorter breast cancer-specific survival, respectively. However, multivariate analysis showed that these associations were not independent of other prognostic variables, namely tumour size, grade, and nodal stage. In conclusion, this study demonstrates that loss of expression of GMPR2 and PPARα is associated with BP at the protein level; indicating that they may play a role in carcinogenesis of this molecularly complex and clinically important subtype. Further studies into their relevance in further classification of BP are warranted.

Calpain system protein expression in basal-like and triple-negative invasive breast cancer

BACKGROUND

Basal-like and triple-negative breast tumours encompass an important clinical subgroup and biomarkers that can prognostically stratify these patients are required.

MATERIALS AND METHODS

We investigated two breast cancer tissue microarrays for the expression of calpain-1, calpain-2 and calpastatin using immunohistochemistry. The first microarray was comprised of invasive tumours from 1371 unselected patients, and the verification microarray was comprised of invasive tumours from 387 oestrogen receptor (ER)-negative patients.

RESULTS

The calpain system contains a number of proteases and an endogenous inhibitor, calpastatin. Calpain activity is implicated in important cellular processes including cytoskeletal remodelling, apoptosis and survival. Our results show that the expression of calpastatin and calpain-1 are significantly associated with various clinicopathological criteria including tumour grade and ER expression. High expression of calpain-2 in basal-like or triple-negative disease was associated with adverse breast cancer-specific survival (P = 0.003 and <0.001, respectively) and was verified in an independent cohort of patients. Interestingly, those patients with basal-like or triple-negative disease with a low level of calpain-2 expression had similar breast cancer-specific survival to non-basal- or receptor- (oestrogen, progesterone or human epidermal growth factor receptor 2 (HER2)) positive disease.

CONCLUSIONS

Expression of the large catalytic subunit of m-calpain (calpain-2) is significantly associated with clinical outcome of patients with triple-negative and basal-like disease.

Basal breast cancer: a complex and deadly molecular subtype

During the last decade, gene expression profiling of breast cancer has revealed the existence of five molecular subtypes and allowed the establishment of a new classification. The basal subtype, which represents 15-25% of cases, is characterized by an expression profile similar to that of myoepithelial normal mammary cells. Basal tumors are frequently assimilated to triple-negative (TN) breast cancers. They display epidemiological and clinico-pathological features distinct from other subtypes. Their pattern of relapse is characterized by frequent and early relapses and visceral locations. Despite a relative sensitivity to chemotherapy, the prognosis is poor. Recent characterization of their molecular features, such as the dysfunction of the BRCA1 pathway or the frequent expression of EGFR, provides opportunities for optimizing the systemic treatment. Several clinical trials dedicated to basal or TN tumors are testing cytotoxic agents and/or molecularly targeted therapies. This review summarizes the current state of knowledge of this aggressive and hard-to-treat subtype of breast cancer.

p16INK4a expression in basal-like breast carcinoma

BLBC represents a distinctive group of invasive breast carcinomas with specific genotype and immunoprofile. BLBC is usually defined by gene expression profiling and is currently associated with poor outcome. BLBCs are estrogen receptor (ER) negative, progesterone receptor (PgR) negative, HER2 negative, and usually show a variable expression of basal cytokeratins (CKs), EGFR and CD117. p16(INK4a) is a tumor suppressor protein, encoded by the CDKN2A gene, which regulates cell cycle. The reported association of abnormalities in the p16/Rb pathway with increased risk of malignancy prompted us to determine the expression of p16(INK4a) in a group of BLBC; the results were compared with a group of high-grade invasive carcinoma (HG-IC) of breast. Tissue microarrays (TMA) were constructed in triplicate including 18 BLBC and 18 HG-IC. All BLBC cases were ER-/PgR-/HER2-. Seventeen (94%) BLBC were CK 5/6+/CK 14+; 14 (78%) BLCB showed EGFR expression and 13 (72%) were CD117 positive. BLBCs showed a strong positive reaction with p16(INK4a) antibody in 16 of 18 (89%) cases. Although the significance of p16(INK4a) expression in breast cancer is not fully understood, we have shown that p16(INK4a) is strongly expressed in breast cancers with basal-like phenotype. Since it is known that p16(INK4a) is associated with aggressive behavior in human carcinomas, these data suggest that p16(INK4a) play a role in the poor prognosis of BLBC.

[Actins and keratins in the diagnosis of human basal-like breast cancer]

The most common forms of luminal breast cancer (BC) were compared with basal-like and Her2/neu3+ BC. Their primary classification was based on morphological diagnosis and the expression of estrogen receptor (ER), progesterone receptor (PR), and Her2/neu receptors. Monoclonal antibodies to actins and keratins were used for the study. Basal-like BC cells (ER/PR/Her2/ neu-) were regularly stained with antibodies to basal keratins 5/6 and 17, smooth muscle alpha-actin, and p63. Luminal keratin 8 staining was reduced. The solid regions had beta-actin staining with disappearance in the scirrhous component. beta-actin and basal keratins were also observed in metaplastic BC with ER/PR/Her2/neu3+. Immunomorphology using cytoskeletal markers along with the expression of steroid hormone and Her2/neu receptors may be used in the diagnosis of basal-like forms of BC.

Differential diagnosis of basal cell carcinoma and benign tumors of cutaneous appendages originating from hair follicles by using CD34

BACKGROUND AND AIMS

Differential diagnosis of the group of benign trichoblastomas, trichofolliculomas, trichoadenomas and trichoepitheliomas, and basal cell carcinomas (BCCs) is troublesome for the clinician as well as the pathologist, especially when only small biopsy specimens are available. Here we investigated whether CD34 expression might be of assistance.

METHODS

Thirty benign tumors of cutaneous appendages originating from hair follicles (BTCOHF) and 30 BCCs were retrieved from our archives and immunohistochemically stained. CD 34 expression was graded from [0] to [2+] and compared among the groups and subgroups.

RESULTS

There was no significant difference between the degree of expression between [0] and [1+] and [0] and [2+] for each group. However, [1+] and [2+] immunopositivity of BTCOHFs was significantly stronger than in BCCs (p= 0.014).

CONCLUSIONS

CD34 may contribute to differential diagnosis of skin lesions.

[Roles of immunohistochemistry in prognostic assessment of basal-like breast cancer]

OBJECTIVES

Basal cell-like breast cancer is one of the subtypes using molecular typing, and this subtype attracted a wide spread attention. Currently, no uniform diagnostic criteria are available. Most studies demonstrated poor outcomes, but contradictory conclusions appeared recently. The prognosis of basal cell-like breast cancer using different immunohistochemical criteria were analyzed.

METHODS

Two hundred and eighty-four invasive breast cancers with a follow-up information over 5 years were evaluated for ER, PR, HER2, CK5/6, CK14, EGFR expression on tissue microarray immunohistochemically. Based on the results, these cases using four different diagnostic criteria were categorized, namely: Nielsen (ER-/HER2-, CK5/6+ and/or EGFR+), Kim (ER-/PR-/HER2-, CK5/6+ and/or CK14+ and/or EGFR+), Triple-negative (ER-/PR-/HER2-), and basal-CK (CK5/6+ and/or CK14+). 5-year survival information was compared between groups.

RESULTS

The prevalence of basal cell-like breast cancer by Nielsen, Kim, Triple-negative and basal-CK were 15.5% (44/284), 14.8% (42/284), 43.3% (123/284) and 21.1% (60/284) respectively; the recurrence rates were 18.2% (8/44), 21.4% (9/42), 10.6% (13/123) and 11.7% (7/60) respectively. These were higher than recurrence rates for other subtypes, but only the differences by Nielsen's and Kim's criteria were significant. Using Nielsen's and Triple-negative's criteria, basal-like tumors showed shorter 5-year disease-free survival (both P < 0. 01) and overall survival (P < 0.05 and 0.01) than luminal A subtype, using Kim's criteria, basal-like tumors showed a lower 5-year disease-free but not overall survival than luminal A subtype (P < 0.01); no significant difference was found on 5-year survival between basal-like and non-basal-like tumors when typed by basal-CK.

CONCLUSION

Basal cell-like breast cancers are more likely to show more recurrence and worse outcome, but different immunohistochemical diagnostic criteria have an influence on their prognostic analysis, so a uniform diagnostic criteria is essential for the further study of basal-like breast cancers.

Frequent PTEN genomic alterations and activated phosphatidylinositol 3-kinase pathway in basal-like breast cancer cells

INTRODUCTION

Basal-like carcinomas (BLCs) and human epidermal growth factor receptor 2 overexpressing (HER2+) carcinomas are the subgroups of breast cancers that have the most aggressive clinical behaviour. In contrast to HER2+ carcinomas, no targeted therapy is currently available for the treatment of patients with BLCs. In order to discover potential therapeutic targets, we aimed to discover deregulated signalling pathways in human BLCs.

METHODS

In this study, we focused on the oncogenic phosphatidylinositol 3-kinase (PI3K) pathway in 13 BLCs, and compared it with a control series of 11 hormonal receptor negative- and grade III-matched HER2+ carcinomas. The two tumour populations were first characterised by immunohistochemistry and gene expression. The PI3K pathway was then investigated by gene copy-number analysis, gene expression profiling and at a proteomic level using reverse-phase protein array technology and tissue microarray. The effects of the PI3K inhibition pathway on proliferation and apoptosis was further analysed in three human basal-like cell lines.

RESULTS

The PI3K pathway was found to be activated in BLCs and up-regulated compared with HER2+ tumours as shown by a significantly increased activation of the downstream targets Akt and mTOR (mammalian target of rapamycin). BLCs expressed significantly lower levels of the tumour suppressor PTEN and PTEN levels were significantly negatively correlated with Akt activity within that population. PTEN protein expression correlated significantly with PTEN DNA copy number and more importantly, reduced PTEN DNA copy numbers were observed specifically in BLCs. Similar to human samples, basal-like cell lines exhibited an activation of PI3K/Akt pathway and low/lack PTEN expression. Both PI3K and mTOR inhibitors led to basal-like cell growth arrest. However, apoptosis was specifically observed after PI3K inhibition.

CONCLUSIONS

These data provide insight into the molecular pathogenesis of BLCs and implicate the PTEN-dependent activated Akt signalling pathway as a potential therapeutic target for the management of patients with poor prognosis BLCs.

Y-box binding protein-1 serine 102 is a downstream target of p90 ribosomal S6 kinase in basal-like breast cancer cells

INTRODUCTION

Basal-like breast cancers (BLBC) frequently overexpress the epidermal growth factor receptor (EGFR) and subsequently have high levels of signaling through the MAP kinase pathway, which is thought to contribute to their aggressive behavior. While we have previously reported the expression of Y-box binding protein-1 (YB-1) in 73% of BLBC, it is unclear whether it can be regulated by a component of the MAP kinase signaling pathway. Phosphorylation of YB-1 at the serine 102 residue is required for transcriptional activation of growth-enhancing genes, such as EGFR. Using Motifscan we identified p90 ribosomal S6 kinase (RSK) as a potential candidate for activating YB-1.

METHODS

Inhibition of RSK1 and RSK2 was achieved using siRNA and the small molecule SL0101. RSK1, RSK2, activated RSK and kinase-dead RSK were expressed in HCC1937 cells. Kinase assays were performed to illustrate direct phosphorylation of YB-1 by RSK. The impact of inhibiting RSK on YB-1 function was measured by luciferase assays and chromatin immunoprecipitation.

RESULTS

Using an in vitro kinase assay, RSK1 and RSK2 were shown to directly phosphorylate YB-1. Interestingly, they were more effective activators of YB-1 than AKT or another novel YB-1 kinase, PKC alpha. Phosphorylation of YB-1 (serine 102 residue) is blocked by inhibition of the MAP kinase pathway or by perturbing RSK1/RSK2 with siRNA or SL0101. In immortalized breast epithelial cells where RSK is active yet AKT is not, YB-1 is phosphorylated. Supporting this observation, RSK2-/- mouse embryo fibroblasts lose the ability to phosphorylate YB-1 in response to epidermal growth factor. This subsequently interfered with the ability of YB-1 to regulate the expression of EGFR. The RSK inhibitor SL0101 decreased the ability of YB-1 to bind the promoter, transactivate and ultimately reduce EGFR expression. In concordance with these results the expression of constitutively active RSK1 increased YB-1 phosphorylation, yet the kinase-dead RSK did not.

CONCLUSIONS

We therefore conclude that RSK1/RSK2 are novel activators of YB-1, able to phosphorylate the serine 102 residue. This provides a newly described mechanism whereby YB-1 is activated in breast cancer. This implicates the EGFR/RSK/YB-1 pathway as an important component of BLBC, providing an important opportunity for therapeutic intervention.

The phenotypic spectrum of basal-like breast cancers: a critical appraisal

There are 2 well-recognized cell populations lining the mammary duct system: the epithelial cells lining the lumen and the myoepithelial cells surrounding them. The mammary stem cell, a putative third cell type, has not yet been well characterized. It is not established whether the putative stem cell expresses the full complement, a subset, or none of the markers of normal epithelial and/or myoepithelial cells. However, it is likely that they would have distinctive markers of their own; whether these are retained or lost in their neoplastic progeny is unknown. All 3 cell types may theoretically undergo malignant transformation. Until recently, however, nearly all attention has been focused on carcinomas of epithelial derivation/differentiation. The advent of oligonucleotide and cDNA microarrays has facilitated gene expression profiling of breast cancers, revealing molecular subclasses that may be prognostically relevant. One such subclass, the basal-like breast carcinomas, has been found in numerous independent datasets to be associated with a comparatively worse overall and disease-free survival. These cancers show expression of molecules characteristic of the normal myoepithelial cell, such as basal cytokeratins, and reduced expression of estrogen receptor-related and Erb-B2-related genes and proteins. The classifier genes that formed the basis for the delineation of basal-like carcinomas were derived from datasets that were composed predominantly of ductal type cancers. Therefore, the clinical significance of a basal-like gene expression or immunohistochemical profile in the other breast cancer subtypes is presently unknown. Herein, we evaluate in detail the current state of knowledge on the pathologic features of breast carcinomas classified as basal-like by immunohistochemical and/or gene expression profiling criteria, with an emphasis on their full phenotypic spectrum and also previously underemphasized areas of heterogeneity and ambiguity where present. There seems to be a phenotypic and biologic spectrum of basal-like or myoepithelial-type carcinomas, just as there is a wide range among tumors of luminal epithelial derivation/differentiation. It is critical to promote lucid morphologic definitions of the molecular subtypes, if this information is intended for use in targeted therapies and patient management.

Poor prognosis in breast carcinomas correlates with increased expression of targetable CD146 and c-Met and with proteomic basal-like phenotype

Genomic studies have led to new taxonomic classifications of breast carcinomas. Proteomic investigations using tissue microarrays have yielded complementary results and are useful in identifying potential molecular targets for specific therapies. Searching for new drug targets is particularly important for tumors of poor prognosis, such as breast tumors that lack estrogen receptors and HER2 amplification; in these tumors, certain molecules probably play a significant role in tumor spreading through the stromal microvasculature. We investigated 930 breast carcinomas categorized according to patients' survival (range of follow-up = 4-10 years; median follow-up = 6.5 years) using (1) automated immunohistochemical procedures (Ventana, Cedex, France) with tissue microarrays (Alphelys, Plaisir, France) and (2) quantification of immunoprecipitates assessed by automated image analysis densitometry (SAMBA, Meylan, France). Expression of c-Met and CD146 and that of signaling transducers PI3K, FAK, and FYN were compared in living and deceased patients. Expression of some proteins recently reported to be characteristic of basal cell carcinomas was also assessed, namely, CK5-6, caveolin-1, carbonic anhydrase IX, p63, and CD117; these also constitute potential targets for therapies for aggressive tumors. Overexpression of these proteins was observed in deceased or metastatic patients (P < .01 to P < .00001), particularly node-negative patients (except for FYN, p63, and CD146). c-Met and CD146 are involved in tumor spreading, and our results suggest that they probably play an important role in patients' death, along with other proteins involved in hypoxia (carbonic anhydrase IX) and other cell functions or structures (caveolin-1, CD117, CK5-6, and p63) that are expressed in an aggressive subtype of basal cell carcinoma for which no specific therapy is available.

Demystifying basal-like breast carcinomas

"Basal" breast cancers are dominating the breast research literature at present and pathologists are under increasing pressure to evaluate for such a phenotype by their surgical and oncological colleagues. There is also much confusion about how to assess cancers, which immunohistochemical markers to use, what meaning and benefit this provides, and what the surgeons and oncologists will do with the information. Much remains to be done to answer all these questions but here we try to shed light on some of the issues and suggest what is still to come.

Sox2: a possible driver of the basal-like phenotype in sporadic breast cancer

Tumours arising in BRCA1 mutation carriers and sporadic basal-like breast carcinomas have similar phenotypic, immunohistochemical and clinical characteristics. SOX2 is an embryonic transcription factor located at chromosome 3q, a region frequently gained in sporadic basal-like and BRCA1 germline mutated tumours. The aim of the study was to establish whether sox2 expression was related to basal-like sporadic breast tumours. Two hundred and twenty-six sporadic node-negative invasive breast carcinomas were immunohistochemically analysed for oestrogen receptor (ER), progesterone receptor (PR), CK5/6, EGFR, vimentin, HER2, ki67, p53 and sox2 using tissue microarrays. Tumours were considered to have basal-like phenotype if they were ER/HER2-negative and CK5/6 and/or EGFR-positive. Thirty cases of this series (13.7%) displayed a basal-like phenotype. Sox2 expression was observed in 16.7% of cases and was significantly more frequently expressed in basal-like breast carcinomas (43.3% in basal-like, 10.6% in luminal and 13.3% in HER2+ tumours, P<0.001). Moreover, Sox2 showed a statistically significant inverse association with ER and PR (P=0.001 and 0.017, respectively) and direct association with CK5/6, EGFR and vimentin (P=0.022, 0.005 and <0.001, respectively). Sox2 is preferentially expressed in tumours with basal-like phenotype and may play a role in defining their less differentiated/'stem cell' phenotypic characteristics.

Relationship of P-cadherin expression to basal phenotype of breast carcinoma

BACKGROUND

P-cadherin (P-CD) is a molecule expressed mainly by basal cells involved in cell adhesion. We evaluated expression of P-CD in operable breast carcinomas and its relationship with immunohistochemical markers of the basal-like phenotype and with clinical outcome.

MATERIAL AND METHODS

Expression of P-CD was analyzed by immunohistochemistry in 194 tissue specimens of invasive operable ductal breast cancer.

RESULTS

112 cases (57.7%) were identified as being P-CD-positive. P-CD-positive tumors usually lacked steroid receptors (p = 0.042), expressed basal type cytokeratins (p = 0.001), and were positive for cyclin E (p = 0.039). In a univariate analysis of cancer-specific survival with a median follow-up period of 58 months, P-CD expression was not associated with prognosis (5-year survival rate for positive vs. negative patients 67.0 vs. 77.0%, log rank p = 0.121).

CONCLUSION

P-CD may be regarded as an additional immunohistochemical marker of basal-like breast carcinomas. However, P-CD expression is not an adverse prognostic factor.

Metaplastic breast carcinomas are basal-like tumours

AIMS

Recently, an immunohistochemical panel comprising antibodies against HER2, oestrogen receptor (ER), epidermal growth factor receptor (EGFR) and cytokeratin (CK) 5/6 was reported to identify basal-like breast carcinomas, as defined by cDNA microarrays. Our aim was to analyse a series of metaplastic breast carcinomas (MBCs) using this panel plus two other basal markers (CK14 and p63) and progesterone receptor (PR), to define how frequently MBCs show a basal-like immunophenotype.

METHODS AND RESULTS

Sixty-five cases were retrieved from the pathology archives of the authors' institutions and reviewed by three of the authors. Immunohistochemistry with antibodies for HER2, ER, EGFR, CK5/6, CK14 and p63 was performed according to standard methods. All but six cases (91%) showed the typical immunoprofile of basal-like tumours (ER- and HER2-, EGFR+ and/or CK5/6+). When CK14 and p63 were added to the panel, two additional cases could be classified as basal-like. The majority of MBCs lacked PR, except 4/19 (21%) carcinomas with squamous metaplasia.

CONCLUSIONS

Our results demonstrate that MBCs show a basal-like phenotype, regardless of the type of metaplastic elements. Moreover, as these neoplasms frequently overexpress EGFR (57%), patients with MBC may benefit from treatment with anti-EGFR drugs.

A subset of prostate basal cells lacks the expression of corresponding phenotypic markers

Immunohistochemical staining for cytokeratin (CK) 34ssE12 has been routinely used to elucidate prostate basal cells for differentiation between non-invasive and invasive lesions. Our previous studies, however, revealed that some morphologically distinct basal cells observed on H&E-stained sections completely lacked CK34ssE12 expression. Our current study attempted to assess whether these basal cells would also lack the expression of other phenotypic markers, and whether basal cell alterations would affect the proliferation status of the associated tumor cells. Consecutive sections from prostate tumors with large basal cell clusters that were morphologically distinct in H&E sections but were completely negative for CK 34ssE12 were morphologically and immunohistochemically assessed with a panel of basal cell phenotypic and other markers. In addition to CK 34ssE12, these basal cells also completely lacked the expression of other phenotypic markers, including CK5, CK14, p63, and maspin, in contrast to adjacent basal cells, which were strongly positive for these markers. Tumors surrounded by basal cell layers that lack the expression of basal cell phenotypic markers showed a significantly higher rate of cell proliferation and mast cell infiltration than their counterparts. These findings suggest that basal cells might be targets of a variety of pathological alterations, which could significantly impact biological presentations of associated tumor cells.

Specific morphological features predictive for the basal phenotype in grade 3 invasive ductal carcinoma of breast

AIMS

Cytokeratin (CK) 14, a myoepithelial marker, is also expressed in a proportion of breast carcinomas. There is evidence that these tumours show a differing metastatic pattern and clinical outcome from other invasive ductal carcinomas (IDCs) and may need different management. Currently, they are not identified in routine practice and no morphological guidelines exist to aid their identification. The aim of this study was to analyse the histological features of CK14+ IDC.

METHODS AND RESULTS

A detailed histological review of 453 grade 3 IDCs revealed 88 (19.4%) that expressed CK14. Assessment was made independently by two pathologists using a standardized 'tick-box' proforma covering grade, architectural and cytological features. The results were analysed using logistic regression to identify features that predicted for basal phenotype. Concordance between the two pathologists was fair to good for most parameters (kappa 0.4-0.6). On multiple logistic regression, the basal phenotype was highly significantly associated with the presence of a central scar (P = 0.005), tumour necrosis (P < 0.0001), presence of spindle cells (P = 0.006) or squamous metaplasia (P < 0.0001), high total mitotic count (> 40 per 10 high-power field) (P = 0.0002) and high nuclear-cytoplasmic ratio (P = 0.0002).

CONCLUSIONS

Specific morphological features are strongly associated with basal-like breast carcinoma. These could be used in routine diagnostic practice to identify this important subset of tumours.

Prognostic significance of basal-like phenotype and fascin expression in node-negative invasive breast carcinomas

PURPOSE

Basal-like phenotype tumors are frequently found among BRCA1 germ-line mutated breast carcinomas. They are biologically aggressive and have a tendency towards visceral metastasis when untreated. Nevertheless, it has been suggested that they respond to chemotherapy better than other types of tumors. Fascin expression has been associated with lung metastasis in breast cancer. The aim of this study was to determine whether basal-like phenotype and fascin were related in both sporadic and familial tumors and with prognosis in node-negative sporadic breast cancers.

EXPERIMENTAL DESIGN

230 nonfamilial and 28 hereditary node-negative invasive breast carcinomas were immunohistochemically analyzed using tissue microarrays. Tumors that were estrogen receptor/HER2 negative and cytokeratin 5/6 and/or epidermal growth factor receptor positive were considered to have a basal-like phenotype.

RESULTS

A basal-like phenotype was found in 11.9% of sporadic cancers. Among patients not receiving adjuvant chemotherapy, a basal-like phenotype was associated with poor prognosis (P = 0.001, log-rank test) whereas no such association was found in patients receiving it. Tumors with a basal-like phenotype showed local recurrence (17.4%) or visceral metastasis (13%) but not bone metastasis (P = 0.001). Fascin expression was observed in 25.1% of sporadic invasive breast carcinomas and was associated with the basal-like phenotype, but not with prognosis or recurrence pattern. Fascin was expressed in 83.3% and 16.7% BRCA1- and BRCA2-associated carcinomas, respectively (P = 0.048).

CONCLUSIONS

Basal-like tumors had a tendency towards visceral metastasis and their prognosis was dependent on the use of postoperative chemotherapy. Although fascin expression was associated with the basal-like phenotype, it was not associated with their metastatic behavior. Fascin expression is frequent in BRCA1-associated tumors.

CD10 expression in trichoepithelioma and basal cell carcinoma

BACKGROUND

Trichoepithelioma (TE) is a benign neoplasm that shares both clinical and histologic features with basal cell carcinoma (BCC). However, it is important to distinguish these neoplasms. Limited immunohistochemical stains are available to separate these two tumors.

METHODS

CD10 protein immunohistochemistry was performed on paraffin-embedded biopsies of 13 TE and 23 BCC diagnosed by routine microscopy. Cases were analyzed for pattern of CD10 expression by tumor cells and surrounding stroma.

RESULTS

Twelve of 13 (92%) TE showed positive stromal immunoreactivity. Of these, eight cases also demonstrated positivity of the papilla, and two also showed positivity of the basaloid cells. No TE demonstrated epithelial expression alone. On the other hand, expression of CD10 by basaloid cells was identified in 20 (87%) cases of BCC. Stromal positivity was also identified in three cases of BCC. Condensation of CD10-positive stromal cells around basaloid nests was statistically significant in differentiating TE from BCC (p < 0.0001). Conversely, CD10-positive basaloid cells were seen predominantly in BCC (p < 0.0001).

CONCLUSIONS

This study demonstrates a statistically significant difference in CD10 staining pattern between TE and BCC. Thus, CD10 may be a useful adjunct marker in distinguishing these tumors.

Myoepithelial cells: pathology, cell separation and markers of myoepithelial differentiation

Until recently the myoepithelial cell has been studied relatively little in terms of its role in breast cancer. A number of malignancies showing myoepithelial differentiation have been reported in the literature, although they are still thought to be relatively rare and only limited studies are published. As a result of recent expression profiling experiments, one type of tumor with myoepithelial features, the so-called 'basal' breast cancer, has received a renewed interest, although it has been known to pathologists for more than two decades. These tumors, which express markers of both luminal and myoepithelial cells, are now being studied using antibodies against some new molecules that have emerged from studies of sorted normal luminal and myoepithelial cells. These immunohistochemical data, combined with genomic studies, may lead to better identification and management of patients with 'basal' tumors.

S100A2 is strongly expressed in airway basal cells, preneoplastic bronchial lesions and primary non-small cell lung carcinomas

S100A2 gene products were shown to be frequently and dramatically over-represented in non-small cell lung cancer (NSCLC) lesions over normal tissue by microarray analysis. We have now analysed an independent series of NSCLC tumours and multiple matched normal bronchial epithelial sites by RT–PCR and immunohistochemistry to investigate: whether this expression pattern can be confirmed and whether elevated expression is associated with tumour histology, clinical outcome or preneoplasia. In this second series, S100A2 was strongly expressed in 76% (35 out of 46) of tumours, more frequently in squamous cell than adenocarcinomas (P<0.002). This strong expression was not related to high-level gene amplification, but was associated in one of five informative cases with an allele-specific imbalance in transcript levels. Most tumours strongly expressed the ΔNp63 transcript, the product of which is a putative regulator of S100A2 transcription and while all but one of the tumours positive for ΔNp63 expressed S100A2, others negative for this regulator also expressed the gene. Contrary to the hypothesis that S100A2 is a tumour suppressor, no somatic mutations were identified in the coding sequence in 44 tumours. Furthermore, an examination of multiple tumour-free epithelial sites from 20 patients showed that strong expression was often associated with increasing levels of disorder in preinvasive bronchial lesions (P<0.0001).

Pathways sufficient to induce epidermal carcinogenesis

Abnormal epidermal proliferation is characteristic of a number of disorders, including the two most common cancers in the United States, basal cell carcinoma (BCC) and squamous cell carcinoma (SCC). Both cancers display a disruption in the normal homeostatic balance between cell division and programmed cell death. While abnormal activation of the sonic hedgehog/patched pathway has been established as sufficient to induce hallmark features of BCC in both human and murine epidermis, pathways sufficient to convert normal epidermis into SCC have been less well defined. Building on findings that indicate a potent role for Ras and NF-kappaB in normal epidermal growth regulation, recent work indicates that activation of Ras signaling in concert with inhibition of NF-kappaB function is entirely sufficient to transform normal human epidermis into tumor tissue with all the cardinal features of SCC.

p53 Gene mutation and genetic instability in superficial multifocal esophageal squamous cell carcinoma

Tumor multicentricity is occasionally observed in esophageal squamous cell carcinoma (SCC). We studied five surgically resected superficial multifocal esophageal SCCs for p53 gene mutation and genetic instability, using DNA extracted from microdissected areas. A total of 38 target areas (TAs) were analyzed in SCC, dysplasia, basal cell hyperplasia (BCH) and normal squamous epithelium. Analysis of the replication error (RER) at 10 microsatellite loci showed microsatellite instability in all TAs, as well as in normal squamous epithelium. p53 gene mutation was identified in 28.9% (11/38 TAs). All cases showed a common missense mutation in exon 8 at codon 273 (CGT-->CAT, Arg-->His), which was DNA contact mutation in the S10 beta strand. In association with microsatellite alterations, 7 of 9 TAs with p53 mutation in exon 8 at codon 273 also showed loss of heterozygosity (LOH) of p53 gene. LOH of p53 gene was detected in 83.8% (31/37 TAs). LOH at D2S123 on 2p16 near MSH2 gene and at D3S1611 on 3p22 near MLH1 gene was detected in 65.4% (17/26) and 71.4% (10/14) TAs, respectively. Frequencies of LOH at p53 and D2S123 were similar in non-cancerous areas and SCCs. LOH of p53 and D2S123 were found in 50% (5/10 TAs) of non-cancerous areas and 60% (9/15 TAs) of SCCs. Our results suggest that genetic instability induces esophageal tumor multicentricity, and that p53 gene contact mutation together with LOH are early events of the multistage carcinogenesis of multifocal primary esophageal SCC.

Craniopharyngioma: a case report and comparative galectin histochemical analysis

Craniopharyngioma is a rare benign tumour originating from Rathke's pouch. This paper reports a tumour case studied with a set of markers defining protein-carbohydrate recognition. Expression of endogenous lectins and their reactive glycoligands is under differentiation-dependent control in many cell types. These parameters can be related to the degree of cell differentiation in tumours. Therefore, the expression patterns of endogenous lectins, namely galectins-1, -3, and -7, in the craniopharyngioma case were determined. Galectins-1 and -3 were also used to reveal glycoconjugates in cells and extracellular matrices, an approach that has heretofore relied largely on plant lectins. The staining pattern of craniopharyngioma is compared with that of two other types of ectodermally derived tumours, namely basal and squamous cell carcinomas. Clusters of polygonal and flattened cells with morphological characteristics of differentiated cells in the craniopharyngioma and the majority of poorly differentiated cells in squamous cell carcinomas were reactive with galectin-3. No binding of this probe was observed in cells of basal cell carcinomas and the majority of craniopharyngioma cells. In view of the lack of accessible binding in the basal layer of normal squamous epithelia where proliferative cells (including stem cells) are located, galectin-3 binding could be used to distinguish basal from suprabasal cells of squamous epithelial cells.

Immunohistochemical and ultrastructural observations of desmoplastic trichoepithelioma with a special reference to a morphological comparison with normal apocrine acrosyringeum

BACKGROUND

Desmoplastic trichoepithelioma is a benign neoplasm considered to have follicular differentiation. Its sweat gland- or sebaceous-lines of differentiation have been also reported. There have been, however, only a few reports regarding extensive immunohistochemical and ultrastructural investigations of this neoplasm.

METHODS

Histopathological and immunohistochemical studies were performed on three cases of desmoplastic trichoepithelioma, comparing it with normal skin. One of these cases was ultrastructurally investigated.

RESULTS

The cord-like basaloid nests were reacted with the anti-cytokeratin (CK)1/5/10/14, -CK5/8, -CK14 and -CK15 antibodies, but not with the anti-CK6 antibody. Similar findings were observed in the outer layers of the normal follicular outer root sheath. Basaloid cell nests in one case, which showed ductal structures in the nests, also expressed CK7, CK8/18 and CK19. These keratins were also detected in the normal sweat glands. In addition, CK8/18 and CK19 were expressed in the basal cells of the outer root sheath. Keratinous cysts had inner reactions with the anti-CK10/11 and -CK6 antibodies, and outer reactions with anti-CK5/8 and -CK14 antibodies. Ultrastructurally, the cells in the cord-like nests were basically immature and basaloid in appearance. A few cells contained Odland bodies, which were also observed in the normal apocrine acrosyringeum. The ductal structure was lined by the cells which bore numerous microvilli in the luminal surface.

CONCLUSION

The cells in desmoplastic trichoepithelioma are suggested to be in close association with the basal cells in the outer root sheath, which can differentiate into various parts of the folliculosebaceous apocrine unit.

Expression of type I hair keratins in follicular tumours

BACKGROUND

Hair keratins are specifically expressed in hair and nails. We previously demonstrated the expression of hair keratin basic 1 mRNA in pilomatrixomas. We recently developed a method for immunohistochemical staining of the group of acidic keratins, which have not yet been investigated in human tumours.

OBJECTIVES

To study the expression of eight members of the type I hair keratin subfamily in pilomatrixomas and other skin tumours of follicular origin.

METHODS

We performed immunohistochemistry on paraffin sections of formalin-fixed pilomatrixomas (40), trichoepitheliomas (10), trichoblastomas (10), desmoplastic trichoepitheliomas (10) and basal cell carcinomas (10), using antibodies against type I hair keratins hHa1, hHa2, hHa3-II, hHa4, hHa5, hHa6, hHa7 and hHa8 as well as cytokeratin CK17.

RESULTS

While CK17 was found in almost all tumours investigated, hair keratins were exclusively expressed in pilomatrixomas. Their expression was restricted to areas of transitional cells, located between outer basophilic matricial cells and an inner zone of eosinophilic shadow cells. The most frequently and most strongly expressed hair keratins were hHa1, hHa2, hHa5 and hHa8, whereas hHa4 and hHa6 were only weakly expressed. No positive staining was observed with anti-hHa3-II and anti-hHa7 antibodies. Hair keratin expression in intermediate maturation stage pilomatrixomas resembled that of normal hair follicles, with early matricial and cuticular keratins hHa5 and hHa2 being expressed in lower transitional cells, followed by expression of early cortex keratins hHa1 and hHa8 in intermediate transitional cells and the late cortex keratins hHa4 and hHa6 in upper transitional cells. The latter were, however, seen only in a few intermediate maturation stage pilomatrixomas and were generally absent in late-stage pilomatrixomas.

CONCLUSIONS

These changes in hair keratin expression patterns indicate that the maturation of pilomatrixomas towards large areas of shadow cells is associated with a gradual loss of differentiation-specific hair keratins. The complex hair keratin expression in pilomatrixomas is a further argument in favour of a hair matrix origin of this tumour.

Bax/bcl-2: cellular modulator of apoptosis in feline skin and basal cell tumours

Bcl-2 and bax are two members of the BCL-2 gene family that play a prominent role in the regulation of apoptosis. Bax and bcl-2 expression were examined immunohistochemically in normal (healthy) feline skin and in 24 benign feline cutaneous basal cell tumours. The tumours were also examined for cellular proliferation by measurement of reactivity for the proliferation marker Ki-67, and for apoptosis by in-situ labelling for fragmented DNA. Bcl-2 was detected in normal basal epithelium and in 23 of 24 basal cell tumours. Bax was detected in both basal and suprabasal epithelium, but in only seven of 24 tumours. For tumours that expressed both bax and bcl-2, the bax:bcl-2 ratio was low. Neither bax nor bcl-2 expression was detected in 14 feline cutaneous squamous cell carcinomas. Basal cell tumours showed modest cellular proliferation (median, 17.5% Ki-67- reactive cells), but few (less than 1%) apoptotic cells. The slow, indolent growth of feline cutaneous basal cells in these benign skin tumours may be a response, at least in part, to opposing regulatory expressions of bcl-2 and bax.

Immunohistochemical evaluation of basal cell carcinoma and trichepithelioma using Bcl-2, Ki67, PCNA and P53

Most basal cell neoplasms with follicular differentiation represent a heterogenous group of tumors. Although may arise anywhere in the skin, these neoplasms commonly occur on the head and neck regions. The majority of these neoplasms are basal cell carcinomas (BCC) and trichoepitheliomas (TE). Overlapping histopathologic features between these benign and malignant tumors are occasionally seen which may create problems in rendering a definitive diagnosis. The intent of this investigation was two-fold: 1) to examine whether there are quantitative differences of the cellular expression of Bcl-2, Ki67, PCNA and P53 between BCC and TE; and 2) to examine the value of these immunostains in differentiating between BCC and TE. Twenty cases of BCC were stained with antibodies for Bcl-2, Ki67, PCNA and P53. The positive cell indices and staining characteristic of these immunostains were compared with those of 20 cases of TE. The cell indices for each group were analyzed statistically utilizing the analysis of variance (ANOVA) technique. Intensity and patterns of Bcl-2 and P53 expression were similar between BCC and TE. The ANOVA analysis showed no statistically significant differences between cell indices for cases stained with antibodies for Bcl-2 and P53 (p=0.49 and p=0.87 respectively) in the two neoplastic groups. There were intense labelling and generalized patterns of Ki67 and PCNA expression in BCC. Conversly, Ki67- and PCNA-labelled cells were much fewer in TEs than those noted in BCCs. Additionally, Ki67- and PCNA-positive cells were limited to the peripheral layers of the neoplastic islands of TEs. There were statistically significant differences between cell indices for cases stained with antibodies for Ki67 and PCNA (p=0.02 and p=0.05 respectively) in the two neoplastic groups. BCC and TE exhibited comparable expressions of Bcl-2 and P53 with similar intensity of labelling and patterns of distribution. This suggests possible similar mechanisms of growth regulation in both neoplasms. However, Ki67 and PCNA labelling was noted with significantly increased numbers and recognizably different patterns in BCCs compared to TEs. This may help explain the significant capabilities in tumor proliferation and the aggressive behavior of BCC compared to the limited growth potential of TE. Additionally, Ki67 and PCNA staining intensity and characteristics may have some value in differentiating between BCC and TE.

CD40 ligation inhibits trichilemmoma cell proliferation and induces IL-6 production

CD40 is a member of the tumor necrosis factor receptor superfamily expressed by B cells, monocytes, dendritic cells, epithelial cells, and hematopoietic progenitor cells. Recently, CD40 has been reported to also be expressed on human epidermal cells. We have elucidated the function of CD40 on epidermal tumor cells and have found that trichilemmoma (KTL-1) cells constitutively express CD40 and respond to CD40 ligation by anti-CD40 mAb (EA-5) with a significant decrease in proliferation. We were also able to demonstrate that KTL-1 cells respond to CD40 ligation by EA-5 with the up-regulation of interleukin-6 (IL-6) mRNA expression. Together, the results suggest that CD40 on KTL-1 cells may function to regulate their proliferation associated with the induction of IL-6 production.

Trichoepithelioma: a 19-year clinicopathologic re-evaluation

Accurate histopathologic distinction between trichoepithelioma (TE) and basal cell carcinoma (BCC) may be challenging. From 97 cases diagnosed as TE during the period 1979-1997, 73 available cases were studied with regard to: 1) stroma; 2) retraction effect; 3) papillary-mesenchymal bodies (PMB); 4) amyloid; 5) mitotic figures; 6) apoptotic cells; 7) inflammation; 8) granuloma; and 9) calcification. A judgment was made regarding diagnosis. The patients' medical records were subsequently reviewed for clinical features and possible recurrence. The diagnosis of TE was confirmed histologically in 48 (65%) of 73 cases. Fifteen cases (21%) were reclassified as BCC (RC-BCC), eight other cases (11%) were reclassified as other lesions, and two additional cases (3%) could not be confidently classified as either TE or BCC. The most helpful differentiating features were the presence of retraction effect (in 100% of RC-BCC vs. 37% of TE), myxoid stroma (in 80% of RC-BCC vs. 12% of TE) and PMB (in 20% of RC-BCC vs. 81% of TE). Unexpected findings in TE were detection of amyloid in 33%, apoptotic cells in 100%, and mitotic figures in 46%. Five of the 15 RC-BCC have recurred (33%), whereas there have been no recurrences in the confirmed TE group. A constellation of histopathologic criteria may help to discriminate problematic examples of trichoepithelioma from basal cell carcinoma.

Analysis of 1,25-dihydroxyvitamin D(3) receptors (VDR) in basal cell carcinomas

We have analyzed expression of 1,25-dihydroxyvitamin D(3) receptor (VDR) protein and mRNA in basal cell carcinomas (BCC) of human skin. VDR immunoreactivity in BCCs was compared with the staining pattern of the proliferation marker Ki-67 in the same tumors. Additionally, VDR staining was compared to staining pattern of apoptotic cells by terminal UTP nucleotide end labeling assay. Frozen sections of superficial type, nodular type, and fibrosing type BCCs were consistently immunoreactive for VDR (mAb 9A7gamma) with almost every tumor cell labeled (n = 15). In general, VDR staining was pronounced in peripheral tumor cells. VDR immunoreactivity was consistently stronger in tumor cells than in adjacent or unaffected epidermis. No visual correlation was found in BCCs comparing labeling patterns of Ki-67-positive or apoptotic cells and mAb 9A7gamma. VDR mRNA was increased in BCCs (n = 6) compared to normal human skin (n = 5), as revealed by reverse transcription-polymerase chain reaction analysis. Our findings indicate that VDR is strongly expressed in BCCs and may be involved in the growth regulation of this tumour, and VDR mRNA and protein are increased in BCCs as compared to normal human epidermis.

Immunohistochemical staining for Ber-EP4, p53, proliferating cell nuclear antigen, Ki-67, bcl-2, CD34, and factor XIIIa in nevus sebaceus

Increased expression of p53 has been found in the majority of basal cell carcinomas (BCCs). The pattern and intensity of this staining, as well as staining for proliferation antigens, seems to correlate with behavior of histologic subtypes of BCC. Nevus sebaceus (NS) is considered a hamartoma. Multiple epithelial neoplasms do arise in NS, and, rarely, they show an aggressive biologic behavior. Significant numbers of these neoplasms, however, have areas of basaloid hyperplasia that are often reported as BCC. Although morphologically similar to BCC, the mechanism underlying the development of these areas has not been investigated, so we sought to evaluate the expression of Ber-EP4, p53, proliferating cell nuclear antigen, Ki-67, bcl-2, Factor XIIIa, and CD34 in areas showing basaloid hyperplasia, arising in NS. We performed immunohistochemical stains for Ber-EP4, p53, proliferating cell nuclear antigen, Ki-67, bcl-2, Factor XIIIa, and CD34 on seven cases of NS with areas of basaloid hyperplasia. All of the eight cases of NS showed diffuse positive membrane staining for Ber-EP4 and negative nuclear staining for p53. Proliferating cell nuclear antigen and Ki-67 staining was only slightly increased in the areas of basaloid hyperplasia, compared with the surrounding epidermis and with areas of the epidermis peripheral to the hamartomatous proliferation, and bcl-2 was only focally positive. Factor XIIIa-positive cells and CD34-positive vascular endothelial cells were increased within the subjacent dermis, a pattern suggestive of follicular differentiation. Our findings suggest that even though areas of basaloid hyperplasia in NS are morphologically similar to BCC, they are induced by different stimulatory and molecular mechanisms. These different mechanisms result in expression of immunohistochemical markers more characteristic of benign follicular tumors than of BCC.