Is p63 reliable in detecting microinvasion in ductal carcinoma in situ of the breast?

Thymidylate Synthase, a New Myoepithelial Biomarker for Breast Lesions

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

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

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

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

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

Phenotypic and Functional Characterization of Ductal Carcinoma In Situ-Associated Myoepithelial Cells

BACKGROUND

Ductal carcinoma in situ (DCIS) is contained by myoepithelial cells that are morphologically similar to normal breast tissue myoepithelial cells. However, phenotypic and functional characteristics of DCIS-associated myoepithelial cells are not known. In this study, we aimed to assess the characteristics of DCIS-associated myoepithelial cells.

MATERIALS AND METHODS

Immunophenotypic and functional characteristics of myoepithelial cells of pure DCIS, the DCIS component of infiltrating duct carcinoma (IDC), and the adjacent normal breast tissue of both groups (30 cases in each group) was assessed using phenotypic (CK5/6, CK14, p63, and calponin) and functional markers (maspin and CXCL14).

RESULTS

There was a decrease in expression of CK14, p63, and calponin in pure DCIS-associated myoepithelial cells compared with normal breast tissue myoepithelial cells (43.3% vs. 80.3%, 3.3% vs. 70%, 46.6 vs. 93.3%, respectively) and in the DCIS component of IDC compared with normal breast tissue myoepithelial cells (56.6% vs. 100%, 3.3% vs. 73.3%, 56.6% vs. 96.6%, respectively). CK5/6 expression was low to absent in myoepithelial cells of pure DCIS and the DCIS component of IDC as well as normal breast tissue myoepithelial cells. Maspin was expressed in all samples of normal breast tissue; however, 20% of pure DCIS and 26.6% of the DCIS component of IDC showed decreased expression. CXCL14 expression was greater in pure DCIS compared with adjacent normal breast tissue and the DCIS component of IDC.

CONCLUSION

Decreased expression of myoepithelial cell markers in DCIS suggests that DCIS-associated myoepithelial cells are phenotypically different from their normal counterparts. Two or more markers, preferably p63 and calponin, should be used to distinguish in situ from invasive breast carcinomas.

Overexpression and ratio disruption of ΔNp63 and TAp63 isoform equilibrium in endometrial adenocarcinoma: correlation with obesity, menopause, and grade I/II tumors

PURPOSE

p63 plays an important role in several intracellular processes such as transcription activation and apoptosis. p63 has two N-terminal isoforms, TAp63 and ΔNp63. TAp63 isoform has p53-like functions, while ΔNp63 acts as a dominant negative inhibitor of the p53 family and is considered oncogenic. Although p63 and its isoforms are overexpressed in a wide variety of human malignancies such as cervical, head and neck, and lung cancer, their role in endometrial carcinoma has not been investigated.

METHODS

We measured by quantitative real-time polymerase chain reaction the mRNA expression of TAp63 and ΔNp63 in a series of 20 endometrioid adenocarcinomas paired with adjacent normal tissue.

RESULTS

TAp63 isoform exhibited 1.8-fold overexpression in malignant samples, while ΔNp63 was 4.3-fold overexpressed in cancer specimens. Further analysis revealed that the ΔN/TA isoform ratio shifted from 0.5 in normal samples to 1.2 in tumor specimens. Statistical analysis also revealed an association of TAp63 expression with high body mass index (p = 0.034), late menopause (p = 0.020), and lower tumor grade (p = 0.034). ΔNp63 was also correlated with grade I/II tumors (p = 0.044).

CONCLUSIONS

These results indicate that both p63 isoforms and especially ΔNp63 play an important role in the development and progression of grade I/II endometrial adenocarcinoma, especially in obese and late-menopause women.

Role of p63 in cancer development

Since their initial identification p53 homologues p63 and p73 have been expected to play a role in cancer development due to their close homology to p53, notoriously one of the most mutated genes in cancer. However soon after their discovery the awareness that these genes were rarely mutated in cancer seemed to indicate that they did not play a role in its development. However a large number of data collected in the following years indicated that altered expression rather than mutation could be found in different neoplasia and play a role in its biology. In particular p63 due to its fundamental role in epithelial development seems to play a role in a number of tumors of epithelial origin. In this review we summarize some of the evidence linking p63 to carcinogenesis.

Frequency of the basal-like phenotype in African breast cancer

Basal-like breast carcinoma has been recognized as a subtype with specific prognostic implications. However, there is a lack of reports about this category of breast tumors in African women. The aim of this study was to explore the basal-like phenotype in breast cancer patients in an African population, and a registry-based series was included from the well-defined Kyadondo County in Uganda (1.7 millions). We studied a total of 65 archival paraffin blocks of invasive breast cancer using antibodies against cytokeratin 5/6 and P-cadherin, and these markers were expressed in 34% of all cases and in 52% of ER (estrogen receptor)-negative tumors. All basal-like tumors were ER negative (p<0.0005) and PR (progesterone receptor) negative (p=0.002). Basal-like breast carcinomas were of a higher histologic grade (p=0.001), had high mitotic counts (p=0.002), and marked nuclear pleomorphism (p=0.002). P-cadherin-positive tumors had a high Ki-67 proliferative rate (p=0.039). In conclusion, the basal-like phenotype is frequent in this African series of breast cancer and is strongly associated with poor prognostic factors. Our findings might be significant in relation to clinical management of these patients, including novel targeted therapy.

Use of p63 and CD10 in the differential diagnosis of papillary neoplasms of the breast

Papillary neoplasms of the breast represent a complex spectrum ranging from benign to malignant lesions. The myoepithelial cell (MEC) layer is generally continuous in papillomas and increasingly discontinuous to absent in atypical and malignant counterparts. Identification of MECs can be difficult on morphological grounds and currently relies on immunomarkers. We investigated the potential role of p63 and CD10 in 20 papillary lesions and compared them with 1A4 and calponin. In 18 cases, adjacent normal breast tissue was available for study. All four markers were diffusely positive in all samples of normal tissue and benign papillomas indicating similar sensitivity in the identification of MECs. Intense positivity was found in 100% of the cases with 1A4 and CD10, but in only 76% with calponin and in 60.5% with p63 (differences statistically significant, p < 0.05), suggesting that the former two render more reproducible results. The most specific markers were p63 and CD10 which showed cross-reactivity in 0% and in up to 33% of the cases respectively. 1A4 and calponin showed diffuse cross-reactivity in all cases. When assessing benign versus atypical papillomas, the best parameters were diffuse positivity using CD10 or p63, and continuous MEC layer, mainly using CD10. When comparing benign papillomas to carcinomas all parameters were equally useful with 1A4 and CD10. Regardless of the marker, intense positivity was the only parameter that could distinguish atypical papillomas from papillary carcinomas. p63 staining, which renders a nuclear and mostly discontinuous reactivity, was not as useful as the other markers when the parameter continuous MEC layer was evaluated. Although CD10 seems to combine the highest specificity and reproducibility with a good sensitivity, reproducibility of 1A4 is higher. Thus, a minimum panel to assess papillary lesions should include both markers. Although p63 is the most specific, its nuclear and discontinuous pattern may lead to erroneous diagnosis, especially in the differentiation between benign papillomas and atypical/malignant lesions.

Immunohistochemical staining of papillary breast lesions

The separation of ductal papilloma from intraductal papillary carcinoma of the breast on hematoxylin and eosin stained sections often presents diagnostic difficulty. Immunohistochemical staining is often employed in diagnosis, historically with smooth muscle actin (SMA). In this study, the staining characteristics of a panel of myoepithelial markers (calponin, p63, P-cadherin), were compared with SMA, and the epithelial expression of CD44s was assessed in 99 papillary lesions. SMA, calponin, and p63 demonstrated myoepithelial cells in 61%, 63%, and 65% of papillary lesions, respectively. However, specificity was quite variable. Calponin-stained stromal myofibroblasts (35% of cases), vessel pericytes (92%), and endothelial cells (69%), though each to a lesser degree than SMA. Calponin also showed cross reactivity with epithelium in 18% of cases. p63 was almost completely restricted to myoepithelial cell nuclei, and did not stain vascular smooth muscle or myofibroblasts. However, p63 stained the epithelial component in one papillary carcinoma, a basal layer of cells in 1 biphasic invasive carcinoma, and the cytoplasm in 1 case. P-cadherin stained both epithelial and myoepithelial cells. The epithelial expression of CD44s and did not distinguish papillomas from papillary carcinomas. Thus, P-cadherin and CD44s are not useful in the characterization of papillary lesions. Given increased specificity as compared with SMA, the combination of p63 and calponin is recommended for analysis of breast papillary lesions.

p63 is useful in the diagnosis of mammary metaplastic carcinomas

AIMS

p63 has been recently reported to be expressed in sarcomatoid/metaplastic carcinoma of the breast, in addition to its role as a myoepithelial marker. A large series of 34 metaplastic carcinomas, including cases with pure epithelial component (squamous cell and adenosquamous carcinomas), biphasic tumours with carcinomatous and sarcomatoid components and monophasic tumours with only spindle cell component, were evaluated for p63 expression with respect to the different cellular components.

METHODS

All of the metaplastic carcinomas were assessed for p63 and conventional epithelial and mesenchymal markers of AE1/3, CAM5.2 and vimentin by immunohistochemistry.

RESULTS

All of the different categories of metaplastic carcinomas showed similar clinico-pathological features (patient age, tumour size, nuclear grade, mitotic activity, lymph node status and hormonal receptor status). For metaplastic carcinoma with epithelial component only, p63 was only expressed in the squamous cell component, but not the adenocarcinoma component. Eight of the 10 tumours were positive for p63. For the tumours with sarcomatoid component, either singly or together with carcinomatous component, p63 was positive in 14 of 24 cases. Pure sarcomas and carcinomas were all negative for p63 staining by immunohistochemistry, thus rendering p63 staining highly specific for diagnosing metaplastic carcinoma.

CONCLUSIONS

Using p63 for diagnosis of metaplastic carcinoma gives a sensitivity of 65%, a specificity of 96%, a positive predictive value of 96%, and a negative predictive value of 66% and an accuracy of 78%. p63 may be used as an adjunct marker in the diagnosis of metaplastic carcinoma.

The role of immunohistochemistry for smooth-muscle actin, p63, CD10 and cytokeratin 14 in the differential diagnosis of papillary lesions of the breast

BACKGROUND

Histological differentiation of mammary papillary lesions can be difficult. The evaluation of myoepithelial cells can be helpful, with benign papilloma showing a continuous myoepithelial cell layer, which becomes attenuated or absent in malignant papillary lesions.

METHODS

A large series of 100 papillomas (28 papillomas with florid epithelial hyperplasia) and 68 papillary carcinomas (9 invasive, 44 in situ, and 15 ductal carcinomas in situ (DCIS) involving papillomas) of the breast were stained for myoepithelial cells by immunohistochemistry using antibodies to smooth-muscle actin (SMA), p63, CD10 and cytokeratin (CK) 14.

RESULTS

In the papillomas, using these four antibodies, myoepithelial cells were positive in 88%, 99%, 91% and 95% of cases, respectively, with SMA showing marked stromal component cell staining and CD10 showing epithelial and stromal staining. CK14 also showed epithelial staining in 71% of papillomas and 96% of papillomas with florid epithelial hyperplasia. In the papillary carcinomas, 36 (53%) cases showed staining of myoepithelial cells that were scattered, discontinuous and diminished in number and the remaining 32 (47%) cases did not show myoepithelial cells. Invasive papillary carcinoma has the lowest proportion (33%) with myoepithelial cells, and DCIS involving papillomas had the highest proportion (87%).

CONCLUSIONS

p63 had the highest sensitivity and did not cross-react with stromal cells and only rarely with epithelial cells. CK14 has the added ability to distinguish between florid epithelial hyperplasia involving papilloma and DCIS involving papillomas. CK14 and p63 may be used as an adjunct in assessing difficult papillary lesions of the breast.

p63 and CD10: Reliable Markers in Discriminating Benign Sclerosing Lesions From Tubular Carcinoma of the Breast?

The immunohistochemical detection of myoepithelial cells in benign sclerosing lesions of the breast is useful in distinguishing them from tubular carcinoma. So far, this detection has been carried out using antibodies against cytoskeletal proteins, such as alpha-smooth muscle actin (1A4) and calponin. However, the specificity of these markers has been questioned since they may be expressed in stromal myofibroblasts and vascular smooth muscle. Recently, two novel myoepithelial markers have been described: the nuclear protein p63, a member of the p53 family, and the surface antigen CD10, also known as common acute lymphoblastic leukemia antigen (CALLA). The authors assessed the use of p63 and CD10 in the differential diagnosis between benign sclerosing lesions, such as sclerosing adenosis and radial scar, and tubular carcinoma, in comparison to the traditional myoepithelial markers 1A4 and calponin. p63, CD10, 1A4, and calponin were expressed in myoepithelial cells of all benign lesions and were consistently negative in all cases of tubular carcinoma. In contrast to cytoskeletal proteins, p63 and CD10 were mostly confined to myoepithelial cells and thus were more specific than the traditional counterparts. However, 1A4 was more intensely expressed and more reproducible than the novel markers. In conclusion, p63 and CD10 may be used as a complement to 1A4 in distinguishing benign sclerosing lesions from tubular carcinoma of the breast.

p63 correlates with both BRCA1 and cytokeratin 5 in invasive breast carcinomas: further evidence for the pathogenesis of the basal phenotype of breast cancer

AIMS

To study the expression of p63, cytokeratin (CK) 5 and CK8/18 in invasive ductal carcinomas and their relationship with BRCA1 and other pathological and immunohistochemical features of clinical significance.

METHODS AND RESULTS

Immunohistochemistry with the antibodies p63, CK5, CK8/18, BRCA1, oestrogen receptor, progesterone receptor, p53, c-erbB-2 and Ki67 was performed in 102 formalin-fixed paraffin-embedded samples of invasive ductal carcinomas. The CK5+ cases were submitted to a double-immunolabelling study with p63. There was a strong relationship between CK5 and p63 expression and both markers were associated with hormonal receptor-negative high-grade carcinomas with high proliferative rate. Furthermore, there was coexpression of CK5 and p63 in neoplastic cells, indicating that p63, like CK5, is a marker of the basal phenotype of breast cancer. There was a strong relationship between reduced expression of BRCA1 with both p63 and CK5 expression as well as an inverse correlation between p63 and CK8/18 expression, suggesting that loss of p63 expression is required for the transition between a basal to a luminal phenotype of breast carcinoma.

CONCLUSIONS

Since p63 is thought to be a marker of stem cells and may act as an oncogene, our data support the idea that BRCA1 acts as stem cell regulator.

[P63 protein in the diagnosis of breast tubular carcinoma]

AIMS

To study and compare the expression of p63 protein and smooth muscle actin in breast tubular carcinoma (TC) and its main differential diagnoses, radial scar (RS)/complex sclerosing lesion (CSL).

MATERIALS AND METHODS

Immunohistochemistry techniques were used to search for p63 protein and smooth muscle actin antibodies in 10 patients with TC and fifteen with RS/CSL.

RESULTS

Myoepythelial cells were diffusely positive for both actin and p63 protein with a cytoplasmic (actin) or nuclear (p63) pattern in all patients with RS/CSL. Inversely, all TC were negative for p63. Actin antibodies failed to label myoepithelial cells in TC, but both vessels and stromal myoblasts were actin-positive, creating difficult interpretation situations. By contrast, p63 was consistently negative in these structures.

CONCLUSION

For the differential diagnosis between TG and CR/LSC, smooth muscle actin and p63 protein demonstrate equivalent sensitivity for the detection of myoepithelial cells. However, the nuclear pattern of p63 labeling gives a "cleaner" stain. In addition, p63 enables distinction between myoepithelial cells and myofibroblasts/vascular smooth muscle cells, offering increased specificity.

p63 and p73: Roles in Development and Tumor Formation

The tumor suppressor p53 is critically important in the cellular damage response and is the founding member of a family of proteins. All three genes regulate cell cycle and apoptosis after DNA damage. However, despite a remarkable structural and partly functional similarity among p53, p63, and p73, mouse knockout studies revealed an unexpected functional diversity among them. p63 and p73 knockouts exhibit severe developmental abnormalities but no increased cancer susceptibility, whereas this picture is reversed for p53 knockouts. Neither p63 nor p73 is the target of inactivating mutations in human cancers. Genomic organization is more complex in p63 and p73, largely the result of an alternative internal promoter generating NH2-terminally deleted dominant-negative proteins that engage in inhibitory circuits within the family. Deregulated dominant-negative p73 isoforms might play an active oncogenic role in some human cancers. Moreover, COOH-terminal extensions specific for p63 and p73 enable further unique protein-protein interactions with regulatory pathways involved in development, differentiation, proliferation, and damage response. Thus, p53 family proteins take on functions within a wide biological spectrum stretching from development (p63 and p73), DNA damage response via apoptosis and cell cycle arrest (p53, TAp63, and TAp73), chemosensitivity of tumors (p53 and TAp73), and immortalization and oncogenesis (ΔNp73).