Expression of p63 in reactive hyperplasias and malignant lymphomas

Prognostic Significance of p53 and p63 in Diffuse Large B-Cell Lymphoma: A Single-Institution Experience

Diffuse large B-cell lymphoma (DLBCL) is the most common lymphoma in adults. We evaluated the immunohistochemical (IHC) expression of p63 and p53 in DLBCL and their significance on overall survival (OS) and progression-free survival (PFS). We conducted a retrospective cohort study of 177 patients with DLBCL who presented to Mount Sinai Medical Center of Florida (Miami Beach, Florida) between 2010 and 2020. IHC staining for p63 and p53 protein expression was performed. A significant correlation was found between p63 positivity and p53 expression, p53/p63 co-positivity, Ki-67 proliferation index, MYC expression, and MYC/BCL2 double expression. Regardless of the germinal center B-cell like (GCB) subgrouping, there was a trend among p53+ patients to have MYC/BCL2 double expression, positive MYC expression, and lower OS and PFS. A tendency of poor OS was seen in p53⁺ patients in the non-GCB, GCB, and double expressors subgroups and poor PFS in p53⁺ patients regardless of the subgrouping. In conclusion, our results suggest that p63 and p53 may represent potential additional prognostic biomarkers in DLBCL and may be included in the initial diagnostic work up of patients with DLBCL.

The TΑp63/BCL2 Axis Represents A Novel Mechanism Of Clinical Aggressiveness In Chronic Lymphocytic Leukemia

High expression of TAp63 is linked to adverse clinical outcomes in CLL.

TAp63 contributes to the antiapoptotic phenotype of CLL cells, likely through modulating BCL2 protein expression.

The TA-isoform of the p63 transcription factor (TAp63) has been reported to contribute to clinical aggressiveness in chronic lymphocytic leukemia (CLL) in a hitherto elusive way. Here, we sought to further understand and define the role of TAp63 in the pathophysiology of CLL. First, we found that elevated TAp63 expression levels are linked with adverse clinical outcomes, including disease relapse and shorter time-to-first treatment and overall survival. Next, prompted by the fact that TAp63 participates in an NF-κB/TAp63/BCL2 antiapoptotic axis in activated mature, normal B cells, we explored molecular links between TAp63 and BCL2 also in CLL. We documented a strong correlation at both the protein and the messenger RNA (mRNA) levels, alluding to the potential prosurvival role of TAp63. This claim was supported by inducible downregulation of TAp63 expression in the MEC1 CLL cell line using clustered regularly interspaced short palindromic repeats (CRISPR) system, which resulted in downregulation of BCL2 expression. Next, using chromatin immunoprecipitation (ChIP) sequencing, we examined whether BCL2 might constitute a transcriptional target of TAp63 and identified a significant binding profile of TAp63 in the BCL2 gene locus, across a genomic region previously characterized as a super enhancer in CLL. Moreover, we identified high-confidence TAp63 binding regions in genes mainly implicated in immune response and DNA-damage procedures. Finally, we found that upregulated TAp63 expression levels render CLL cells less responsive to apoptosis induction with the BCL2 inhibitor venetoclax. On these grounds, TAp63 appears to act as a positive modulator of BCL2, hence contributing to the antiapoptotic phenotype that underlies clinical aggressiveness and treatment resistance in CLL.

p63 expression in human tumors and normal tissues: a tissue microarray study on 10,200 tumors

Background

Tumor protein 63 (p63) is a transcription factor of the p53 gene family involved in differentiation of several tissues including squamous epithelium. p63 immunohistochemistry is broadly used for tumor classification but published data on its expression in cancer is conflicting.

Methods

To comprehensively catalogue p63 expression, tissue microarrays (TMAs) containing 12,620 tissue samples from 115 tumor entities and 76 normal tissue types were analyzed.

Results

p63 expression was seen in various normal tissues including squamous epithelium and urothelium. At least occasional weak p63 positivity could be detected in 61 (53%) of 115 different tumor types. The frequencies of p63 positivity was highest in squamous cell carcinomas irrespective of their origin (96–100%), thymic tumors (100%), urothelial carcinomas (81–100%), basal type tumors such as basal cell carcinomas (100%), and various salivary gland neoplasias (81–100%). As a rule, p63 was mostly expressed in cancers derived from p63 positive normal tissues and mostly not detectable in tumors derived from p63 negative cancers. However, exceptions from this rule occurred. A positive p63 immunostaining in cancers derived from p63 negative tissues was unrelated to aggressive phenotype in 422 pancreatic cancers, 160 endometrium cancers and 374 ovarian cancers and might be caused by aberrant squamous differentiation or represent stem cell properties. In 355 gastric cancers, aberrant p63 expression occurred in 4% and was linked to lymph node metastasis (p = 0.0208). Loss of p63 in urothelial carcinomas - derived from p63 positive urothelium - was significantly linked to advanced stage, high grade (p < 0.0001 each) and poor survival (p < 0.0001) and might reflect clinically relevant tumor dedifferentiation.

Conclusion

The high prevalence of p63 expression in specific tumor types makes p63 immunohistochemistry a suitable diagnostic tool. Loss of p63 expression might constitute a feature of aggressive cancers.

Supplementary Information

The online version contains supplementary material available at 10.1186/s40364-021-00260-5.

Microsecretory adenocarcinoma of the hard palate: A case report of a recently described entity

We report a case of microsecretory adenocarcinoma of the hard palate. The patient is a 37-year-old woman with a 15 mm submucosal tumor, which was incidentally found by her primary care dentist, in her hard palate. Preoperative magnetic resonance imaging revealed a tumor exhibiting high signal on T2-weighted image, which was gradually enhanced on dynamic study. Histologically, the tumor border was ill-defined without fibrous capsule and adjoined minor salivary gland with permeative infiltration at the tumor periphery. The tumor comprised intercalated duct-like cells with polygonal narrow eosinophilic to clear cytoplasm and small, uniform oval nuclei. These cells formed small infiltrative microcysts, tubules and fascicular cords collecting pale basophilic secretions and small vacuoles setting in an abundant fibromyxoid stroma. The tumor cells were positive for CK AE1+AE3, S-100 protein, and p63, while are completely negative for p40, alpha-SMA, and calponin. The MEF2C-SS18 fusion was identified by reverse transcriptase-polymerase chain reaction followed by Sanger sequencing. The combination of characteristic histology, immunophenotype, and presence of MEF2C-SS18 fusion indicated the diagnosis of microsecretory adenocarcinoma of the hard palate, an entity described only recently. Post-operative course was uneventful and there was no evidence of disease at 4 months after surgery.

An Algorithmic Immunohistochemical Approach to Define Tumor Type and Assign Site of Origin

Immunohistochemistry represents an indispensable complement to an epidemiology and morphology-driven approach to tumor diagnosis and site of origin assignment. This review reflects the state of my current practice, based on 15-years' experience in Pathology and a deep-dive into the literature, always striving to be better equipped to answer the age old questions, "What is it, and where is it from?" The tables and figures in this manuscript are the ones I "pull up on the computer" when I am teaching at the microscope and turn to myself when I am (frequently) stuck. This field is so exciting because I firmly believe that, through the application of next-generation immunohistochemistry, we can provide better answers than ever before. Specific topics covered in this review include (1) broad tumor classification and associated screening markers; (2) the role of cancer epidemiology in determining pretest probability; (3) broad-spectrum epithelial markers; (4) noncanonical expression of broad tumor class screening markers; (5) a morphologic pattern-based approach to poorly to undifferentiated malignant neoplasms; (6) a morphologic and immunohistochemical approach to define 4 main carcinoma types; (7) CK7/CK20 coordinate expression; (8) added value of semiquantitative immunohistochemical stain assessment; algorithmic immunohistochemical approaches to (9) "garden variety" adenocarcinomas presenting in the liver, (10) large polygonal cell adenocarcinomas, (11) the distinction of primary surface ovarian epithelial tumors with mucinous features from metastasis, (12) tumors presenting at alternative anatomic sites, (13) squamous cell carcinoma versus urothelial carcinoma, and neuroendocrine neoplasms, including (14) the distinction of pheochromocytoma/paraganglioma from well-differentiated neuroendocrine tumor, site of origin assignment in (15) well-differentiated neuroendocrine tumor and (16) poorly differentiated neuroendocrine carcinoma, and (17) the distinction of well-differentiated neuroendocrine tumor G3 from poorly differentiated neuroendocrine carcinoma; it concludes with (18) a discussion of diagnostic considerations in the broad-spectrum keratin/CD45/S-100-"triple-negative" neoplasm.

Expression of P63 and its correlation with prognosis in diffuse large B-cell lymphoma: a single center experience

Background

Large B cell lymphoma (DLBCL) is the most common type of non-Hodgkin’s lymphoma among adults. In some cases, DLBCL may seem similar to carcinoma cells, presenting a round, oval, or polygonal shape and clear nuclei. We found that the expression of P63 accounted for a considerable proportion of DLBCL cases. Under the circumstances, P63 expression may lead to a misdiagnosis, especially with a small biopsy. We aim to investigate the expression status and prognostic significance of P63 in a cohort of Chinese DLBCL patients.

Methods

P63, ΔNP63(P40), P53 and Ki67 were detected by immunohistochemistry (IHC). A ROC curve was adopted to find the best cut-off value for positive P63/P53 expression and high Ki67 expression. We defined P53 as positive when ≥50% of the tumor cells showed staining. The relationship between P63 and P53/Ki67 expression was examined. Time-to-event endpoints were estimated according to the Kaplan-Meier method. Moreover, multivariate analyses were conducted to evaluate the prognostic factors in DLBCL.

Results

Out of all the 159 DLBCL cases, 76 (47.8%) expressed P63 in the nuclei, while 41 (25.8%) were determined to have high expression by using a ROC cut-off value “≥6”. Examination of the different P63 isoforms revealed that the ΔNP63(P40) was unclearly and weakly expressed in only 3 cases, showing a fuzzy yellow cytoplasm. P63 expression was not correlated with subtype (GCB or non-GCB) or P53 but was correlated with a high proliferative index (Ki67). Kaplan-Meier analyses revealed that P63 expression was correlated with overall survival, and P63 positive cases showed poor survival outcomes (P<0.05) in our cohort.

Conclusions

ΔNP63(P40) is a useful marker in the differential diagnosis of poorly differentiated squamous cell carcinoma versus DLBCL in small needle biopsy. P63 may be involved in DLBCL tumor progression, and it is an unfavorable prognostic marker in DLBCL. A subgroup of P63 and P53 coexpression DLBCL patients with an extremely poor prognosis should be noted.

Potential role of TP63 in apical periodontitis development

AIM

To investigate the expression of TP63 in apical periodontitis (AP) tissues and the association of single nucleotide polymorphisms (SNPs) in the TP63 gene with AP using a case-control dataset.

METHODOLOGY

Expression of TP63 in human AP lesions (apical abscess, radicular cyst, periapical granuloma) was evaluated using immunohistochemistry. A case-control association study was performed to assess the association of TP63 polymorphisms in individuals having AP with or without associated pain. Cases were defined as subjects with deep caries and AP (n = 151) and subjects with symptomatic apical periodontitis or acute apical abscess (n = 124). Subjects without AP (n = 169) and asymptomatic (n = 196) were used as controls, respectively. Saliva samples were collected as source of genomic DNA. Twelve SNPs in the TP63 gene were selected for genotyping using Taqman chemistry in real-time PCR. Data analysis was performed using PLINK software. The Bonferroni method was applied to correct for multiple testing; α ≤ 0.004 indicates significant differences between groups.

RESULTS

TP63 expression was evident in apical abscesses and radicular cysts, while weaker expression was observed in periapical granulomas. Positive expression was observed in mononuclear cells in the granulation tissues of all AP lesions. Regarding the presence of AP, a trend for allelic association was observed for rs16864812 and rs9810322 (P = 0.04) and rs9810322 genotypes were also nominally associated with AP under a dominant model (P = 0.04). When considering the presence of periapical pain, a trend for allelic and genotypic association was observed for rs10155037 (P = 0.03). Haplotypes were also associated with AP and periapical pain (P ≤ 0.05).

CONCLUSIONS

Apical periodontitis is a complex multifactorial condition and it is likely that multiple genes and environmental effects may influence its susceptibility, progression or both. TP63 variants may play a role in AP pathogenesis and susceptibility, individually or interactively with other genes. Additional studies in other populations and functional studies are needed to improve understanding of the role of TP63 in AP.

Role of Immunocytochemistry in the Cytological Diagnosis of Pulmonary Tumors

Pulmonary cytology is a challenging diagnostic tool, and it is usually evaluated considering medical history and radiological findings in order to reach an accurate diagnosis. Since the majority of lung cancer patients have an advanced stage at diagnosis, a cytological specimen is frequently the only material available for diagnosis and further prognostic/predictive marker determination. Several types of specimens can be obtained from the respiratory system (including sputum, bronchoalveolar lavage, bronchial brushing, fine needle aspiration, and pleural fluid) with different technical preclinical management protocols and different diagnostic yields. Immunocytochemistry (ICC) has a pivotal role in the determination of diagnostic, prognostic, and predictive markers. Therefore, limited cytology samples are to be used with a cell-sparing approach, to allow both diagnostic ICC evaluation as well as predictive marker assessment by ICC or specific molecular assays. In this review, we describe the most common ICC markers used for the diagnosis and prognostic/predictive characterization of thoracic tumors in different cytological specimens.

Hematologic Malignancies of the Breast: A Contemporary Series Investigating Incidence, Presentation, Accuracy of Diagnosis on Core Needle Biopsy, and Hormone Receptor Expression

Background

Distinguishing breast hematologic malignancies in core needle biopsies from other entities can be challenging. Misclassification as a breast carcinoma could result in inappropriate treatment. The aim of this study was to characterize the types, incidence, and helpful diagnostic features of hematologic malignancies of the breast.

Design

All hematologic malignancies of the breast diagnosed at our institution from 2004 to 2017 were identified. Clinical notes, imaging, and slides were reviewed. Immunohistochemical analysis of estrogen receptor α (ERα), estrogen receptor β (ERβ), and androgen receptor (AR) was performed when tissue was available.

Results

In all, 43 hematologic malignancies from biopsies of 37 women and 6 men were identified. Core needle biopsies (35 or 81%) were more common than excisions (8 or 19%). For 14 patients (40%), the core biopsy was the first diagnosis of a hematologic malignancy. Diagnoses included 37 lymphomas (7 primary), 4 leukemias, and 2 myelomas. There was 1 misdiagnosis of carcinoma. Low positivity for hormone receptors was observed in a minority of lymphomas. A definitive diagnosis of hematologic malignancy was made in 31 (89%) of the core needle biopsies. Only 3 patients undergoing core biopsy required excision for diagnosis.

Conclusions

Most of the hematologic malignancies of the breast are currently diagnosed on core needle biopsy and 40% of patients do not have a prior history. To avoid errors, pathologists need to be aware of diagnostic features and morphologic mimics. A hematologic malignancy should be considered if tumor cells are discohesive, carcinoma in situ is absent, and hormone expression is low or absent.

p63 expression confers significantly better survival outcomes in high-risk diffuse large B-cell lymphoma and demonstrates p53-like and p53-independent tumor suppressor function

The role of p53 family member, p63 in oncogenesis is the subject of controversy. Limited research has been done on the clinical implications of p63 expression in diffuse large B-cell lymphoma (DLBCL). In this study, we assessed p63 expression in de novo DLBCL samples (n=795) by immunohistochemistry with a pan-p63-monoclonal antibody and correlated it with other clinicopathologic factors and clinical outcomes. p63 expression was observed in 42.5% of DLBCL, did not correlate with p53 levels, but correlated with p21, MDM2, p16^INK4A, Ki-67, Bcl-6, IRF4/MUM-1 and CD30 expression, REL gains, and BCL6 translocation. p63 was an independent favorable prognostic factor in DLBCL, which was most significant in patients with International Prognostic Index (IPI) >2, and in activated-B-cell–like DLBCL patients with wide-type TP53. The prognostic impact in germinal-center-B-cell–like DLBCL was not apparent, which was likely due to the association of p63 expression with high-risk IPI, and potential presence of ∆Np63 isoform in TP63 rearranged patients (a mere speculation). Gene expression profiling suggested that p63 has both overlapping and distinct functions compared with p53, and that p63 and mutated p53 antagonize each other. In summary, p63 has p53-like and p53-independent functions and favorable prognostic impact, however this protective effect can be abolished by TP53 mutations.

A Case of p63 Positive Diffuse Large B Cell Lymphoma of the Bladder

Diffuse large B cell lymphoma (DLBCL), currently the most common type of non-Hodgkin lymphoma (NHL), is an aggressive B cell neoplasm that typically presents in older adults as a rapidly enlarging mass. The enlarging mass typically represents a lymph node, although extranodal disease can occur in a significant percentage (40%) of cases. The most common extranodal sites of involvement include the gastrointestinal tract and skin; primary bladder lymphoma represents only 0.2% of extranodal non-Hodgkin lymphomas. We report a case of diffuse large B cell lymphoma occurring in the bladder of an 83-year-old gentleman with an initial presentation of hematuria. This neoplasm displayed large, atypical cells with vesicular chromatin and prominent nucleoli that involved the bladder mucosa with invasion into muscularis propria, prostate, and urethra. Positive staining for p63 initially raised suspicion for poorly differentiated urothelial carcinoma; however, lack of staining for pancytokeratin and positive staining for LCA, CD20, CD79a, and PAX-5 confirmed the diagnosis of diffuse large B cell lymphoma. Though it does not occur in all cases, p63 can be positive in a significant percentage of cases of DLBCL; therefore, a diagnosis of lymphoma remains an important entity on the differential diagnosis of aggressive and particularly poorly differentiated neoplasms.

Immunocytochemical p63 expression discriminates between primary cutaneous follicle centre cell and diffuse large B cell lymphoma-leg type, and is of the TAp63 isoform

AIMS

The p63 gene shares structural and functional homologies with the p53 family of transcriptional activators, but differs in exhibiting a consistent expression pattern in normal tissues. Although p63 is rarely mutated in malignancy studies of primary human tumours and cell lines suggest that p63 may promote tumour development. In non-Hodgkin's nodal lymphoma, TAp63 expression in follicular lymphoma (54%) and diffuse large B cell lymphoma (34%) has been described and correlated with the proliferative index. In this study, we analysed a series of primary cutaneous B cell lymphomas for immunohistochemical expression of p63.

METHODS AND RESULTS

Thirty cases of diffuse large B cell lymphoma leg type (pcDLBCLL) and 34 cases of follicle centre cell lymphoma (pcFCCL) were stained using a generic antibody to p63, and a subset of these with an antibody specific for delta-Np63 isoform. The results indicate a significant difference between pcDLBCLL (21 of 30) and pcFCCL (four of 34) in p63 expression (P = 0.000); expression correlated strongly with the proliferation rate as assessed by Ki-67 (P = 0.015). None of the p63((+)) cases tested expressed the delta-Np63 isoform, suggesting that expression is of the TAp63 isoform.

CONCLUSIONS

Functional studies are required to clarify the significance of p63 overexpression in primary cutaneous B cell lymphoma.

Polymorphous low grade adenocarcinoma has a consistent p63+/p40- immunophenotype that helps distinguish it from adenoid cystic carcinoma and cellular pleomorphic adenoma

Polymorphous low grade adenocarcinoma (PLGA) is a tumor of minor salivary glands that exhibits considerable morphologic overlap with adenoid cystic carcinoma and cellular pleomorphic adenoma, especially in small biopsy specimens. Unlike these other tumor types. PLGAs do not harbor a myoepithelial component, yet their frequent positivity for p63 diminishes the usefulness of this particular myoepithelial marker as a discriminating immunostain. p40 is an antibody that recognizes ΔNp63, a p63 isoform that is more specific for true myoepithelial differentiation. As such, p40 immunostaining could help distinguish PLGAs from adenoid cystic carcinomas and pleomorphic adenomas. In this study, p63 and p40 immunohistochemistry was performed on paraffin embedded, formalin fixed tissue from 11 PLGAs, 101 adenoid cystic carcinomas, and 31 pleomorphic adenomas. All 11 PLGAs (100 %) were positive for p63 but completely negative for p40. Among adenoid cystic carcinomas, 91 of 101 (90 %) were positive for p63 and 90/101 (89 %) were positive for p40. The single discordant p63+/p40- adenoid cystic carcinoma exhibited solid architecture and high grade features not typically seen in PLGA. Among pleomorphic adenomas, 21/31 (68 %) were positive for p63 and 13/31 (42 %) were positive for p40. For the pleomorphic adenomas, the discordant p63+/p40- staining pattern was seen only in the overtly mesenchymal chondromyxoid stroma. The cellular epithelial component of the pleomorphic adenomas demonstrated concordant p63+/p40+ or p63-/p40- immunophenotypes. PLGA consistently exhibits a p63+/p40- immunophenotype that can help distinguish it from adenoid cystic carcinoma and cellular pleomorphic adenoma, tumors that characteristically demonstrate concordant p63 and p40 immunostaining patterns. A p63/p40 immunohistochemical panel can provide a valuable tool for making the distinction between these morphologically similar but clinically divergent entities.

Immunohistochemistry for the novel markers glypican 3, PAX8, and p40 (ΔNp63) in squamous cell and urothelial carcinoma

OBJECTIVES

To examine squamous cell carcinomas (SCCs) from diverse anatomic sites and invasive urothelial carcinomas (UCs) for expression of the oncofetal antigen glypican 3 (GPC3), the paired box transcription factor PAX8, and the ΔN isoform of p63 (p40).

METHODS

Immunohistochemistry for GPC3, PAX8, and p40 was performed on whole sections of 107 SCCs from 11 anatomic sites and 49 UCs; evaluation included extent and intensity of staining.

RESULTS

GPC3 was detected in 20% of SCCs and 12% of UCs and PAX8 in 3% of SCCs, limited to the uterine cervix, and 10% of UCs. p40 Was found in 99% of SCCs and 96% of UCs.

CONCLUSIONS

GPC3 expression is frequent in SCC/UC, awareness of which should guard against an incorrect diagnosis of hepatocellular carcinoma, while PAX8, limited in distribution, may have some use in suggesting a cervical or urothelial tract origin in a metastatic squamotransitional carcinoma of unknown primary. There is no drop-off in sensitivity for the diagnoses of SCC or UC with ΔNp63-specific immunohistochemistry, and if this performance can be extended to other applications, p40 may supplant the dominant "pan-p63" antibody clone.

Utility of p40 in the Differential Diagnosis of Small Round Blue Cell Tumors of the Sinonasal Tract

The sinonasal tract may give rise to a broad range of neoplasms that share a "small round blue cell" tumor (SBRCT) appearance on routine histology, but treatment strategies depend on precise tumor classification. Immunohistochemistry for p63 is often employed in the sinonasal SRBCT differential diagnosis because it is highly sensitive for squamous cell carcinoma (SCC). However, p63 staining may be observed in other tumor types, a potential diagnostic pitfall. P40 is a more squamous-specific isoform of p63, and it may be more useful in distinguishing poorly differentiated SCC from its mimickers in the sinonasal tract. Immunohistochemistry for p40 and p63 was performed on 171 sinonasal neoplasms with SRBCT morphology: 73 SCCs (67 poorly differentiated, non-keratinizing, or basaloid types and 6 nasopharyngeal carcinomas), 46 esthesioneuroblastomas, 11 sinonasal undifferentiated carcinomas (SNUCs), 11 lymphomas, 9 melanomas, 7 alveolar rhabdomyosarcomas, 4 solid adenoid cystic carcinomas, 4 NUT midline carcinomas, 4 primitive neuroectodermal tumors (PNETs), and 2 small cell carcinomas. P40 was positive in 72 of 73 SCCs, and showed a diffuse distribution in all but one positive case. P40 immunoexpression was also observed in 13 of 46 (28 %) esthesioneuroblastomas, 6 of 11 (55 %) SNUCs, 2 of 4 (50 %) adenoid cystic carcinomas, 3 of 4 (75 %) NUT midline carcinomas, 1 of 2 (50 %) small cell carcinomas, and 1 of 4 (25 %) PNETs; in the non-SCC tumors, p40 staining was focal in most cases. P63 was positive in every p40-positive tumor. In addition, a p63+/p40- phenotype was seen 5 of 11 (45 %) lymphomas, 4 of 7 (57 %) alveolar rhabdomyosarcomas, 1 of 4 (25 %) PNETs, and 3 of 46 (7 %) esthesioneuroblastomas. All sinonasal melanomas were negative for both markers. In the sinonasal SRBCT differential diagnosis, both p40 and p63 are highly sensitive for SCC, but p40 is more specific. Notably, p40 is consistently negative in lymphomas and alveolar rhabdomyosarcomas, two tumors that are frequently p63-positive. It must be remembered, however, that even diffuse p40 immunostaining is not entirely specific for the squamous phenotype, and therefore it should be utilized as part of an immunohistochemical panel.

Pro-apoptotic TP53 homolog TAp63 is repressed via epigenetic silencing and B-cell receptor signalling in chronic lymphocytic leukaemia

Chronic lymphocytic leukaemia (CLL) is an accumulative disorder marked by deficient apoptosis. The TP53 homolog TAp63 promotes apoptosis and chemosensitivity in solid tumours and its deregulation may contribute to CLL cell survival. We found that TAp63α was the most prevalent TP63 isoform in CLL. Compared to healthy B cells, TAp63 mRNA was repressed in 55·7% of CLL samples. TP63 promoter methylation was high in CLL and inversely correlated with TP63 protein expression in B-cell lymphoma cell lines. siRNA-mediated knockdown of TP63 resulted in partial protection from spontaneous apoptosis accompanied by reductions in PMAIP1 (NOXA), BBC3 (PUMA), and BAX mRNA in CLL cells and increased proliferation of Raji lymphoma cells. TAp63 mRNA levels were higher in CLL with unmutated IGHV. B-cell receptor (BCR) engagement led to repression of TP63 mRNA expression in malignant B cells, while pharmacological inhibition of BCR signalling prevented TP63 downregulation. MIR21, known to target TAp63, correlated inversely with TAp63 expression in CLL, and BCR-mediated downregulation of TP63 was accompanied by MIR21 upregulation in most CLL samples. Our data illustrate the pro-apoptotic function of TP63, provide insights into the mechanisms of BCR-targeting agents, and establish a rationale for designing novel approaches to induce TP63 in CLL and B-cell lymphoma.

p63 and p53 expression in extranodal NK/T cell lymphoma, nasal type

OBJECTIVES

To investigate the pathological and clinical meaning of p63 in extranodal nasal type NK/T cell lymphoma (NKTCL).

METHODS

We detected p63 and p53 expression using immunohistochemistry staining in 84 cases of NKTCL from Southern of China, an area with a well known high incidence of nasopharyngeal carcinoma, which is closely associated with Epstein-Barr virus infection. Moreover, we analysed the relationship between p63 and p53 expression and the clinicopathological features of NKTCL.

RESULTS

Our results first showed that p63 expression was found in 14.3% (12/84) of NKTCL compared with 6.6% (2/30) in reactive lymphoid hyperplasia of nasopharynx. p63 Expression rate in NKTCL was significantly higher than that in reactive lymphoid hyperplasia of nasopharynx (p=0.016). NKTCL patients with p63 positivity had poorer 5-year overall survival rate (29.2%) than that (49.9%) of p63 negativity. p53 expression was found in 33.3% (28/84) of NKTCL. Our data showed that p53 expression was significantly associated with tumour stage (p=0.016) and international prognostic index (p=0.026) in patients with NKTCL. Cox regression test showed that p53 expression rate and international prognostic index score were statistically independent prognostic factors for NKTCL patients (p=0.002 and p=0.016, respectively). Our results suggest that p63 and p53 might play a role in pathogenesis of NKTCL.

Upregulation of cell adhesion through delta Np63 silencing in human 5637 bladder cancer cells

Some researchs have demonstrated that the loss of delta Np63 is associated with aggressive phenotypes and poor prognosis. However, other research indicates that delta Np63 is considered to have oncogenic properties. Delta Np63 overexpression is often observed in association with the oncogenic growth of squamous cell carcinomas and bladder cancer. In this study, we investigated the oncogenic role of delta Np63 in regulating cell adhesion in transitional cell carcinoma of the bladder (TCCB). The cells were stably transfected with the delta Np63 short hairpin RNA (shRNA) plasmid. Immunocytochemistry was performed to determine the knockdown efficiency. Tumour cells were studied for their ability to adhere to vascular endothelial cells. Confocal microscopy was used to analyse the changes in cytoskeletal F-actin. F-actin expression was measured by flow cytometry. Cell invasion ability was assessed using transwell chambers. The delta Np63-silenced tumour cells were shown to adhere more tightly than controls to vascular endothelial cells (P<0.05). The content of F-actin in the delta Np63-silenced cells was enhanced (P<0.05). The Matrigel invasion assays showed that human 5637 bladder cancer cells had a lower degree of motility when transfected with pdelta Np63-shRNA (P<0.05). In conclusion, silencing of the delta Np63 expression can enhance the adhesiveness of 5637 cells by inducing F-actin cytoskeleton production, and it will possibly inhibit the TCCB invasion and metastasis.

Role of p53 family members p73 and p63 in human hematological malignancies

p53, mutated in over half of human cancers and about 13% of all hematological malignancies, maintains genomic integrity and triggers cellular senescence and apoptosis of damaged cells. In contrast to p53, the homologs p73 and p63 play critical roles in development of the central nervous system and skin/limbs, respectively. Moreover, dependent on the context they can exert tumor suppressor activities that cooperate with p53. Unlike p53, p73 and p63 are rarely mutated in cancers. Instead, up-regulation of the anti-apoptotic dominant-negative ΔNp73 and ΔNp63 isoforms is the most frequent abnormality in solid cancers. In hematological malignancies the most frequent p73 defect is promoter methylation and loss of expression, associated with unfavorable clinical outcomes. This suggests an essential tumor suppressor role of p73 in blood cells, also supported by genetic mouse models. Many therapeutic approaches aiming to restore p73 activity are currently being investigated. In contrast, the most frequent p63 abnormality is protein overexpression, associated with higher disease grade and poorer prognosis. Surprisingly, although available data are still scarce, the emerging picture is up-regulation of transactivation-competent TAp63 isoforms, suggesting a tumor-promoting role in this context.

p40 (ΔNp63) is superior to p63 for the diagnosis of pulmonary squamous cell carcinoma

Immunohistochemistry has recently emerged as a powerful ancillary tool for differentiating lung adenocarcinoma and squamous cell carcinoma-a distinction with important therapeutic implications. Although the most frequently recommended squamous marker p63 is extremely sensitive, it suffers from low specificity due to its reactivity in a substantial proportion of lung adenocarcinomas and other tumor types, particularly lymphomas. p40 is a relatively unknown antibody that recognizes ΔNp63-a p63 isoform suggested to be highly specific for squamous/basal cells. Here we compared the standard p63 antibody (4A4) and p40 in a series of 470 tumors from the archives of Memorial Sloan-Kettering Cancer Center and The Johns Hopkins Hospital, which included lung squamous cell carcinomas (n=81), adenocarcinomas (n=237), and large cell lymphomas (n=152). The p63 was positive in 100% of squamous cell carcinomas, 31% of adenocarcinomas, and 54% of large cell lymphomas (sensitivity 100%, specificity 60%). In contrast, although p40 was also positive in 100% of squamous cell carcinomas, only 3% of adenocarcinomas, and none of large cell lymphomas had p40 labeling (sensitivity 100%, specificity 98%). The mean percentage of p63 versus p40-immunoreactive cells in squamous cell carcinomas was equivalent (97 vs 96%, respectively, P=0.73). Rare adenocarcinomas with p40 labeling had reactivity in no more than 5% of tumor cells, whereas the mean (range) of p63-positive cells in adenocarcinomas and lymphomas was 26% (1-90%) and 48% (2-100%), respectively. In summary, p40 is equivalent to p63 in sensitivity for squamous cell carcinoma, but it is markedly superior to p63 in specificity, which eliminates a potential pitfall of misinterpreting a p63-positive adenocarcinoma or unsuspected lymphoma as squamous cell carcinoma. These findings strongly support the routine use of p40 in place of p63 for the diagnosis of pulmonary squamous cell carcinoma.

Calretinin staining facilitates differentiation of olfactory neuroblastoma from other small round blue cell tumors in the sinonasal tract

OBJECTIVE

Olfactory neuroblastoma (ONB) is an uncommon malignant tumor of the sinonasal tract and has a wide histologic differential diagnosis that includes other small round blue cell tumors (SRBCTs). Even with the use of immunohistochemistry (IHC), the correct diagnosis may be difficult, especially in small biopsies. The purpose of this study is to determine the usefulness of calretinin and p63 as an aid to distinguish ONB from other sinonasal SRBCTs.

METHODS

IHC staining for calretinin and p63 was performed on 21 specimens diagnosed as ONB and on 42 other sinonasal SRBCTs. Specimens were retrieved from the files of the QEII HSC, Halifax and UHN, Toronto.

RESULTS

All but 1 ONB (20 of 21) showed calretinin staining, with 15 of 21 showing staining in >75% of the tumor area and 18 of 21 showing moderate-to-strong staining intensity. Only pituitary adenomas (3 of 3) and a single case of small cell carcinoma, neuroendocrine type (1 of 2), showed a similar staining pattern. None of the ONBs showed staining for p63. P63 was positive in all cases of nonkeratinizing squamous cell carcinoma (2 of 2) and in single cases of mantle cell lymphoma (1 of 1) and poorly differentiated neuroendocrine carcinoma (1 of 1); however, it inconsistently stained diffuse large B-cell lymphoma (4 of 5), extranodal NK/T-cell lymphoma, nasal type (1 of 4), sinonasal undifferentiated carcinoma (1 of 6), and Ewing sarcoma/primitive neuroectodermal tumor (2 of 6).

CONCLUSIONS

Calretinin appears to be a useful marker to distinguish ONBs from other SRBCTs of the sinonasal tract, particularly when staining is moderate/strong and extensive. The calretinin-positive, p63-negative phenotype is fairly specific for ONB. The addition of these 2 IHC stains may aid in the diagnosis of sinonasal SRBCTs that are poorly differentiated, have inconclusive conventional IHC, or are found in small biopsies.

Immunohistochemical profile and fluorescence in situ hybridization analysis of diffuse large B-cell lymphoma in northern China

CONTEXT

Gene expression profiling of diffuse large B-cell lymphoma using complementary DNA microarrays has revealed 2 major prognostic groups in Western countries: germinal center B-cell-like and nongerminal center B-cell-like lymphomas. Immunohistochemical analysis using antibodies specific for CD10, BCL6, and MUM1 has been proposed as a surrogate for gene expression profiling.

OBJECTIVE

To study the immunohistochemical features of diffuse large B-cell lymphoma cases from northern China because geographic differences for this disease are known to exist.

DESIGN

Morphologic, immunohistochemical, and fluorescence in situ hybridization analyses of 63 cases of diffuse large B-cell lymphoma from northern China.

RESULTS

There were 38 men and 25 women with a median age of 57 years (range, 12-87 years). CD10 was positive in 19 cases (30%), BCL6 was positive in 22 cases (35%), and MUM1 was positive in 32 cases (51%). Twenty-one (33%) cases were germinal center B-cell-like lymphoma, and 42 (67%) were nongerminal center B-cell-like lymphoma. BCL2 was expressed more often in nongerminal center B-cell-like disease versus germinal center B-cell-like disease (60% versus 24%, P = .01) and in nodal versus extranodal (64% versus 30%, P = .01) cases. Fluorescence in situ hybridization analysis showed BCL6, MYC , and BCL2 rearrangements in 11 of 32 (34%), 8 of 27 (30%), and 11 of 50 (22%) cases, respectively.

CONCLUSIONS

These results add to what is known about the geographic variation of diffuse large B-cell lymphomas. In northern China, the frequency of the germinal center B-cell-like type and BCL6 expression and/or BCL6 rearrangement is less and the frequency of MYC rearrangement is greater than have been reported in Western countries.

Impaired delta NP63 expression is associated with poor tumor development in transitional cell carcinoma of the bladder

The oncogenic isoform of the p63 protein, delta Np63 (delta Np63), plays an important role in the pathogenesis of many epithelial carcinomas, and emerging evidences suggest that delta Np63 is a promising drug target. However, the functions of delta Np63 in transitional cell carcinoma of bladder (TCCB) are poorly defined. In this study, a delta Np63 shRNA expression vector was transfected into TCCB cell line 5637 and cell cycling, cell proliferation and protein expression were assessed by flow cytometry and 3-(4, 5-Dimethylthiazol-2-yl)-2, 5-dimethyl tetrazolium bromide (MTT) assay, and immunohistochemistry, respectively. The delta Np63 shRNA expression vector was also injected into 5637 cell xenograft tumors in nude mice, and tumor size was measured, tumor tissue morphology was assessed by immunohistopathology and transmission electron microscopy. In the in vitro study, delta Np63 shRNA transfection caused successful delta Np63 gene silencing and resulted in significant arrest of cell cycling and cellular proliferation (p<0.05) as well as cyclin D1 expression. In the nude mouse xenograft model, delta Np63 shRNA greatly inhibited tumor growth, induced tumor cell apoptosis (p<0.05) and resulted in cyclin D1 downregulation. Our data suggest that delta Np63 may play an oncogenic role in TCCB progression through promoting cell survival and proliferation. Intratumoral administration of delta Np63-specific shRNA suppressed tumor delta Np63 expression and cellular proliferation while promoted tumor cellular apoptosis, and therefore inhibited tumor growth and improved survival of xenograft-bearing mice, which was not accompanied by significant signs of systemic toxicity.

Expression of p63 in anaplastic large cell lymphoma but not in classical Hodgkin's lymphoma

Immunohistochemical determination of p63 protein is frequently used in the pathologic diagnosis of nonhematological solid tumors. In malignant hematological disease, p63 expression has been reported in 22% of follicular lymphoma, about 35% of diffuse large B-cell lymphoma, 23% of chronic lymphocytic leukemia, and in some cases of blast crisis of chronic myelogenous leukemia. Anaplastic large cell lymphoma is a rare disease that accounts for less than 5% of all cases of non-Hodgkin's lymphoma. There is little information concerning p63 expression in this specific type of lymphoma. In some cases, the morphological and phenotypic features between anaplastic large cell lymphoma and classical Hodgkin's lymphoma are similar, making this differential diagnosis challenging. We studied p63 expression using a tissue microarray approach in 154 cases of anaplastic large cell lymphoma, including 38% anaplastic large cell kinase positive and 62% anaplastic large cell kinase negative, and 58 Hodgkin's lymphoma cases. Sixty-eight cases of anaplastic large cell lymphoma (44%) showed p63 nuclear positivity (41% of anaplastic large cell kinase positive and 47% of anaplastic large cell kinase negative). Of 130 cases of systemic-anaplastic large cell lymphoma, 42% showed p63 positivity. The neoplastic cells expressed p63 in 38% of the cases of CD45-negative/anaplastic large cell kinase-negative null cell-type anaplastic large cell lymphoma, a subgroup that offers the most difficulties in the differential diagnosis with classical Hodgkin's lymphoma. In contrast, none of the cases of classical Hodgkin's lymphoma demonstrated any p63 expression. These results demonstrate that p63 protein expression is frequently expressed in a subset of anaplastic large cell lymphoma cases and may be used as a potential tool in the differential diagnosis between anaplastic large cell lymphoma and classical Hodgkin's lymphoma.

CD74 induces TAp63 expression leading to B-cell survival

Most mature follicular B cells circulate within the periphery in a quiescent state, without actively contributing to an acute immune response. Lasting B-cell persistence in the periphery is dependent on survival signals that are transduced by cell surface receptors. We recently demonstrated that cell surface CD74 controls mature B-cell survival. Stimulation of cell surface CD74 leads to NF-kappaB activation, which enables entry of the stimulated B cells into the S phase, induction of DNA synthesis, and cell division, and augments the expression of survival genes. In the present study, we investigated CD74 target genes to determine the identities of the molecules whose expression is modulated by CD74, thereby regulating B-cell survival. We report that CD74 activates the p65 member of the NF-kappaB family, which in turn up-regulates the expression of p53-related TAp63 proteins. TAp63 then binds and transactivates the Bcl-2gene and induces the production of Bcl-2 protein, thereby providing the cells with increased survival capacity. Thus, the CD74/NF-kappaB/TAp63 axis defines a novel antiapoptotic pathway in mature B cells, resulting in the shaping of both the B-cell repertoire and the immune response.