Relation between apocrine differentiation and receptor status, prognosis and hormonal response in breast cancer

Runx2 controls a feed-forward loop between androgen and prolactin-induced protein (PIP) in stimulating T47D cell proliferation

Prolactin-Induced Protein (PIP) is a small polypeptide expressed by breast and prostate cancer (BCa, PCa) cells. However, both the regulation of PIP expression and its function in cancer cells are poorly understood. Using BCa and PCa cells, we found that Runx2, a pro-metastatic transcription factor, functionally interacts with the Androgen Receptor (AR) to regulate PIP expression. Runx2 expression in C4-2B PCa cells synergized with AR to promote PIP expression, whereas its knockdown in T47D BCa cells abrogated basal as well as hormone stimulated PIP expression. Chromatin immunoprecipitation (ChIP) assays showed that Runx2 and AR co-occupied an enhancer element located ∼11 kb upstream of the PIP open reading frame, and that Runx2 facilitated AR recruitment to the enhancer. PIP knockdown in T47D cells compromised DHT-stimulated expression of multiple AR target genes including PSA, FKBP5, FASN, and SGK1. The inhibition of AR activity due to loss of PIP was attributable at least in part to abrogation of its nuclear translocation. PIP knockdown also suppressed T47D cell proliferation driven by either serum growth factors or dihydrotestosterone (DHT). Our data suggest that Runx2 controls a positive feedback loop between androgen signaling and PIP, and pharmacological inhibition of PIP may be useful to treat PIP positive tumors.

Preferential HER-2/neu overexpression and/or amplification in aggressive histological subtypes of invasive breast cancer

AIMS

To investigate whether alterations of the HER2 gene occur more frequently in histologically unfavourable subtypes of invasive breast cancer.

METHODS

The study was composed of nine invasive apocrine, six lipid-rich, 12 glycogen-rich, 11 micropapillary and 33 pleomorphic lobular breast carcinomas. Lymph node involvement was represented in all subgroups. HER2 status was confirmed in all cases by using immunohistochemistry (CB11, Herceptest) and fluorescent in-situ hybridization (FISH) analysis (Vysis).

RESULTS

Micropapillary and apocrine carcinomas showed the highest rate of protein overexpression (72% and 66%) and gene amplification (45% and 44%). Protein overexpression was common in poorly differentiated pleomorphic lobular carcinomas (56%); however, this subgroup failed to show an increased number of gene copies by FISH (31%). The incidence of HER2 overexpression (33% and 50%, respectively) and gene amplification (25% and 33%, respectively) among glycogen-rich and lipid-rich carcinomas was not higher than that observed in breast cancer generally.

CONCLUSION

Our data suggest that preferential involvement of the HER2 gene in micropapillary and apocrine breast carcinomas may contribute to their aggressive behaviour.

Androgen receptors frequently are expressed in breast carcinomas: potential relevance to new therapeutic strategies

BACKGROUND

Several studies have demonstrated the biologic and therapeutic significance of estrogen and progesterone receptors (ER and PR) in breast carcinomas. The aim of the current study was to examine the presence of androgen receptors (AR) in breast carcinomas.

METHODS

Two hundred cases of breast carcinoma, consisting of 145 invasive and 55 noninvasive (ductal carcinoma in situ [DCIS]) lesions, were examined using a monoclonal antibody against AR on formalin-fixed, paraffin-embedded archival material. The results were analyzed for correlations with immunohistochemically determined ER, PR, and HER-2/neu expression.

RESULTS

Eighty-seven of the 145 cases (60%) of invasive carcinoma and 45 of the 55 cases (82%) of DCIS were AR-positive according to internationally standardized guidelines. The vast majority of Grade 1 carcinomas were positive for AR (90% of invasive Grade 1 carcinomas and 95% of Grade 1 DCIS), whereas in Grade 3 invasive carcinomas and DCIS, positive immunoreactions for AR were observed in 46% and 76% of cases, respectively. Among the cases of Grade 3 carcinoma, 33 invasive carcinomas (39%) and 17 DCIS lesions (68%) were ER-negative but AR-positive. Among Grade 1 carcinomas (invasive and DCIS), not a single case was positive for HER-2/neu, but most cases were intensely positive for AR. In contrast, many invasive Grade 3 carcinomas exhibited agreement between AR status and HER-2/neu status (AR-positive and HER-2/neu-positive, 30.5%; AR-negative and HER-2/neu-negative, 42.5%).

CONCLUSIONS

Androgen receptors are commonly expressed in DCIS and in invasive breast carcinoma. A significant number of poorly differentiated carcinomas are ER-negative and PR-negative but AR-positive. Immunohistochemical examination of AR would be desirable because it would provide additional information about steroid receptors in breast carcinomas.

Androgen and estrogen receptor mRNA status in apocrine carcinomas

Eleven pure apocrine carcinomas (8 breast, 2 vulvar, 1 axillary) were evaluated for the presence of androgen and estrogen receptor mRNA. These immunohistochemically androgen receptor positive and estrogen receptor negative cases were microdissected and analyzed by the reverse transcription polymerase chain reaction for the presence of receptor message. Nine of these 11 estrogen receptor (ER) negative lesions were found to contain the ER mRNA through the first intron splice region. In 4 of the 11 cases, the androgen receptor (AR) mRNA could not be shown even though the protein was detected immunohistochemically. In the other seven, AR mRNA was identified. This indicates that the mechanism for production of the estrogen receptor is intact and functional in most cases through the first transcriptional splice region. Therefore, the immunohistochemical absence of the estrogen receptor in apocrine cells cannot be explained by an abnormal message at these common sites and should be sought beyond these points.

Androgen receptor CAG repeat lengths in ductal carcinoma in situ of breast, longest in apocrine variety

CAG repeat number in the androgen receptor (AR) has been associated with decreased prostate cancer risk, and AR expression has been found in female breast cancer, often associated with apocrine differentiation. Because trinucleotide expansion can alter gene expression and protein function, we hypothesized that it might occur in breast neoplasms. We used a repeat expansion detection technique to determine CAG repeat lengths in DNA from breast biopsies. Three lesion types were microdissected: fibroadenoma (48 cases), ductal carcinoma in situ (DCIS, 24 cases), and invasive mammary carcinoma (18 cases). The maximum number of CAG repeats in either allele of each patient in these three groups was compared. Microsatellite repeat lengths in DCIS were longer than in fibroadenomas or invasive carcinomas (P= 0.017 comparing DCIS vs invasive carcinomas). Two cases of apocrine DCIS had very long repeat lengths, both exhibiting microsatellite lengths at the longest range of normal (32 and 33). Inherited differences in AR CAG length might influence the transition from DCIS to invasive breast cancer, perhaps by modulating function of AR in breast tissue. AR microsatellite polymorphisms could influence cellular differentiation in DCIS lesions, promoting formation of the apocrine subtype in the presence of longer CAG repeats.

Immunohistochemical analysis of GCDFP-15 and GCDFP-24 in mammary and non-mammary tissue

BACKGROUND

Gross cystic disease fluid protein (GCDFP)-15, a major constituent protein in breast cysts, is known to be a marker of breast cancer, while the diagnostic value of GCDFP-24, a protein with a molecular weight of 24,000 daltons, has not been determined. The aim of this study was to elucidate the usefulness of GCDFP-24 for the differential diagnosis of breast cancer in combination with GCDFP-15 and to characterize the histologic features of GCDFP-24-positive breast cancer.

METHODS

A total of 326 samples including non-neoplastic tissue and benign and malignant tumors from several anatomic sites were examined using commercially available monoclonal antibodies against GCDFP-15 and GCDFP-24.

RESULTS

In non-mammary tissue, GCDFP-15 was detected in skin, salivary gland, bronchial gland, prostate and seminal vesicle, and GCDFP-24 was detected in apocrine glands and peripheral nerve. Thirty-seven (44.6%) and 22 (26.5%) samples of 83 breast cancers were positive for GCDFP-15 and -24, respectively. Combined assays of GCDFP-15 and -24 raised the positive rate to 50.6%. The markers were not detected in tumors originating from gastrointestinal tract, bronchopulmonary structures or the genitourinary system. Breast cancers positive for both GCDFP-15 and GCDFP-24 were of lower histologic grade according to Bloom & Richardson's scoring system (p < 0.05).

CONCLUSION

Immunohistochemical analysis of GCDFP-24 in combination with GCDFP-15 expression was useful for definitive diagnosis of breast cancers, and the expression of these markers correlated with low grade breast cancer.

The potential role for prolactin-inducible protein (PIP) as a marker of human breast cancer micrometastasis

The prolactin-inducible protein (PIP/GCPD15) is believed to originate from a limited set of tissues, including breast and salivary glands, and has been applied as a clinical marker for the diagnosis of metastatic tumours of unknown origin. We have investigated the potential role of PIP mRNA as a marker of human breast cancer metastasis. Using reverse transcription polymerase chain reaction and Southern or dot blot analysis, PIP mRNA was detected in 4/6 breast cell lines, independent of oestrogen receptor (ER) status. In breast primary tumours (n = 97), analysed from histologically characterized sections, PIP mRNA was detected in most cases. Higher PIP mRNA levels correlated with ER+ (P = 0.0004), progesterone receptor positive (PR+) (P = 0.0167), low-grade (P = 0.0195) tumours, and also PIP protein levels assessed by immunohistochemistry (n = 19, P = 0.0319). PIP mRNA expression was also detectable in 11/16 (69%) of axillary node metastases. PIP mRNA expression, however, was also detected in normal breast duct epithelium, skin, salivary gland and peripheral blood leucocyte samples from normal individuals. We conclude that PIP mRNA is frequently expressed in both primary human breast tumours and nodal metastases. However, the presence of PIP expression in skin creates a potential source of contamination in venepuncture samples that should be considered in its application as a marker for breast tumour micrometastases.

Diagnostic immunohistochemistry of cutaneous metastatic breast carcinoma: a statistical analysis of the utility of gross cystic disease fluid protein-15 and estrogen receptor protein

BACKGROUND

For accurate classification of cutaneous metastatic carcinoma, reliable tumor-specific immunohistochemical markers would be valuable.

OBJECTIVE

Our purpose was to analyze the sensitivity, specificity, and positive predictive value of gross cystic disease fluid protein-15 (GCDFP-15) and estrogen receptor protein (ERP) for diagnosing cutaneous metastatic breast carcinoma.

METHODS

Tissue sections from 68 consecutive cases of cutaneous metastatic carcinoma were stained for GCDFP-15 and ERP. Hematoxylin-eosin-stained slides and immunostained slides were reviewed in a blinded fashion before retrospective chart review to ascertain the underlying primary tumor type.

RESULTS

Of 42 cases of cutaneous metastatic breast carcinoma, 30 were positive for GCDFP-15. Of 41 cases of metastatic breast carcinoma, 30 were positive for ERP. Calculated sensitivity, specificity, and positive predictive value for GCDFP-15 for diagnosing cutaneous metastatic breast carcinoma were 71%, 91%, and 94%, respectively, and 73%, 100%, and 100% for ERP, respectively. Combined values of these indices for both stains were 83%, 91%, and 95%, respectively.

CONCLUSION

GCDFP-15 and ERP are valuable markers for cutaneous metastatic breast carcinoma and should be used in combination.

Mitogenic effect of the 15-kDa gross cystic disease fluid protein (GCDFP-15) on breast-cancer cell lines and on immortal mammary cells

The biological significance of a major protein component in the fluid of gross cystic breast disease and a recognized marker of apocrine metaplasia, i.e. the 15-kDa glycoprotein (GCDFP-15), is presently unknown. We have added GCDFP-15 to cell culture medium and tested its effect on proliferation of 4 human breast-cancer cell lines (MCF7, BT474, MDA-MB231 and T47D) and a "normal" human immortal breast-cell line (MCF10A). These breast-cell lines showed a mitogenic response to GCDFP-15 (10 micrograms/ml). GCDFP-15 enhanced cell growth of the MCF10A, MCF7, BT474 and MDA-MB231 cell lines at both 48 and 96 hr of exposure. The glycoprotein exerted a mitogenic effect on the T47D cell line at 48 hr but not at 96 hr. This may be due to an auto-regulatory effect of endogenous GCDFP-15 synthesized by the T47D cells. GCDFP-15 was ineffective on 2 colon-cancer cell lines (HT29 and NIC-H716), on the IMR32 neuroblastoma cell line and on the NIC-H209 small-cell lung carcinoma cells. A separate major breast cystic disease fluid protein of 24 kDa (GCDFP-24) was tested, following the same experimental design, on the 5 breast-cell lines, and showed no mitogenic activity. The mitogenic effect of GCDFP-15 observed in this study in both "normal" and malignant breast epithelial cells suggests a possible relationship between apocrine metaplasia in breast cystic disease and the development of breast epithelial hyperplasia. In addition, a possible role of GCDFP-15 in breast-cancer progression should be considered.

PIP/GCDFP-15 gene expression and apocrine differentiation in carcinomas of the breast

The frequency and the significance of apocrine differentiation in carcinomas of the breast are uncertain, because of the lack of reliable and reproducible criteria for morphological diagnosis. The 15 kDa glycoprotein of cystic breast disease (GCDFP-15) is regarded as a specific functional marker of apocrine cells. Expression of the prolactin-inducible protein (PIP)/GCDFP-15 gene was investigated by Northern blot analysis and in situ hybridization in breast cancer cell lines and in an unselected series (33 cases) of primary carcinomas of the breast. On the same cases, histological assessment of apocrine differentiation and immunocytochemical detection of GCDFP-15 were also performed and correlated with follow-up data. The presence of PIP/GCDFP-15 mRNA was a feature of a relatively high number of cases, but was incompletely correlated with histological and immunocytochemical evidences of apocrine differentiation. Expression of the PIP/GCDFP-15 gene was significantly associated with relapse-free survival, and may represent a novel variable of functional and prognostic relevance.

Zinc alpha-2 glycoprotein levels in serum and breast fluids: a potential marker of apocrine activity

Zinc alpha-2 glycoprotein (ZnGP) was measured in human breast microcysts, breast secretions, breast cyst fluid and serum. Detectable amounts of ZnGP were found in all fluids but the highest levels were found in microcysts. Apocrine macrocysts had a higher ZnGP level than flattened macrocysts. In both cysts and secretions levels of ZnGP correlated with those of dehydroepiandrosterone sulphate. Levels were significantly higher in cyst fluids from women who developed further cysts during follow-up compared with those in fluid from women who did not. Concentrations of ZnGP in serum from breast cancer patients were significantly higher than controls but not women with breast cysts. Women with node positive breast cancer had higher serum levels compared with those in node negative patients. Women with more advanced breast cancer had higher serum ZnGP levels than those with earlier disease. ZnGP is a serum and breast marker of apocrine activity and may prove to be a useful prognostic marker in breast cancer.