Androgen and androgen-metabolizing enzymes in metastasized lymph nodes of breast cancer

The role of 17βHSDs in breast tissue and breast cancers

The family of seventeen beta hydroxysteroid dehydrogenase enzymes has a long and diverse history in breast and breast cancer research. Given the known dependence of the breast on steroid signalling and intracrine steroid metabolism these enzymes are considered to be essential local fine tuners of overall steroid balance in the tissue. This review will cover the current state of knowledge regarding the expression, clinical effect and biological regulation of enzymes in both cancerous and normal states. In addition we will also cover the current state of knowledge regarding 17βHSD actions in the often neglected adipose and stromal components of tumours.

The prognostic value of androgen receptors in breast cancer subtypes

PURPOSE

Androgen receptor (AR) expression is frequent in breast cancer and has been associated with good prognosis in several studies. The present study investigates AR-expression in relation to molecular subtypes, clinicopathological features and prognosis in 1297 primary tumours and 336 paired axillary lymph node metastases (LNM) from two cohorts of Norwegian patients.

METHODS

Immunohistochemistry for AR was performed on tumours previously reclassified into molecular subtypes using immunohistochemistry and in situ hybridisation. Associations between AR-expression and clinical features were studied using Chi-square tests. Cumulative incidence of breast cancer death and Cox regression analyses were used to assess prognosis.

RESULTS

AR-positivity was found in 78.0% of all cases, 84.9% of luminal and 45.1% of non-luminal tumours. The highest proportion of AR-positivity was found in Luminal B tumours, and the lowest in the Basal phenotype. Discordance in AR-status between primary tumours and lymph node metastases was observed in 21.4% of cases. A switch from AR^- primary tumour to AR⁺ lymph node metastasis was seen in 60/72 discrepant cases. AR-expression in primary tumours was an independent and favourable prognostic marker (HR 0.70, 95% CI 0.55-0.90), particularly in the Luminal A subtype, and in grade 3 tumours.

CONCLUSIONS

AR is an independent predictor of good prognosis in BC, particularly in grade 3 and Luminal A tumours. Discordant AR-expression between primary tumour and LNM was observed in 21.4% of cases and most often there was a switch from AR^- primary tumour to AR⁺ axillary LNM.

Androgen and breast cancer: an update

PURPOSE OF REVIEW

The review is targeted at describing the advances in our understanding of androgen actions in the breast over the last 18 months. Androgens are current 'hot topics' in breast cancer because of their potential as therapeutics in situations where we currently do not have good clinical options. This is true for both estrogen receptor alpha (ERα) negative and ERα positive cancers.

RECENT FINDINGS

The review has focused on examining associations between androgen receptor and patient prognosis and outcomes in different breast cancer subtypes. A logical extension of this is covering the timely topic of the use of androgen-directed therapy in these patients. The principle settings in which this is being considered is in ERα positive cancer with therapeutic resistance to ER-directed therapies and in ERα negative breast cancer that lack current standard targeted therapies. Finally interactions between mutations, and the potential role of androgen in the normal hierarchy of mammary cell differentiation and the relationship of this to cancer, are considered.

SUMMARY

Androgens are firmly established as important factors across multiple breast cancer subtypes. The future challenge for basic researchers and important development for clinicians is going to be translating this understanding into effective therapeutics for the benefit of breast cancer patients.

Androgen receptor expression predicts beneficial tamoxifen response in oestrogen receptor-α-negative breast cancer

Background:

Although the androgen receptor (AR) is frequently expressed in breast cancer, its relevance in the disease is not fully understood. In addition, the relevance of AR in determining tamoxifen treatment efficiency requires evaluation.

Purpose:

To investigate the tamoxifen predictive relevance of the AR protein expression in breast cancer.

Methods

Patients were randomised to tamoxifen 40 mg daily for 2 or 5 years or to no endocrine treatment. Mean follow-up was 15 years. Hazard ratios were calculated with recurrence-free survival as end point.

Results:

In patients with oestrogen receptor (ER)-negative tumours, expression of AR predicted decreased recurrence rate with tamoxifen (hazard ratio (HR)=0.34; 95% confidence interval (CI)=0.14–0.81; P=0.015), whereas the opposite was seen in the AR− group (HR=2.92; 95% CI=1.16–7.31; P=0.022). Interaction test was significant P<0.001. Patients with triple-negative and AR+ tumours benefitted from tamoxifen treatment (HR=0.12; 95% CI=0.014–0.95 P=0.044), whereas patients with AR− tumours had worse outcome when treated with tamoxifen (HR=3.98; 95% CI=1.32–12.03; P=0.014). Interaction test was significant P=0.003. Patients with ER+ tumours showed benefit from tamoxifen treatment regardless of AR expression.

Conclusions:

AR can predict tamoxifen treatment benefit in patients with ER− tumours and triple-negative breast cancer.

Beyond the C18 frontier: Androgen and glucocorticoid metabolism in breast cancer tissues: The role of non-typical steroid hormones in breast cancer development and progression

Breast cancer's hormonal dependence is well known and has been so for a long time. However in the last two decades great advances have been made in understanding the local metabolism of steroids within tissue. In the form of aromatase inhibition this is already one of the mainstays of breast cancer therapy. This review aims to summarise briefly what is known in terms of the metabolism of C18 steroids but perhaps more importantly to touch on the new developments regarding the importance of the metabolism of androgens and glucocorticoids in breast tissue. It is our hope that this review should provide the reader with a "birds eye view" of the current state of knowledge regarding localised steroid metabolism in the breast.

Androgen receptor and enzymes in lymph node metastasis and cancer reoccurrence in triple-negative breast cancer

BACKGROUND

Triple-negative breast cancer (TNBC) is characterized by the absence of estrogen receptor, progesterone receptor and HER2. TNBCs are a diverse subgroup, but one promising marker and therapeutic target of this breast cancer is the androgen receptor (AR). Previously we demonstrated that AR and cognate intracrine pathways are associated with decreased proliferation in invasive ductal carcinoma with their decrease also detected between organ-confined and invasive diseases. Therefore, in this study, we examined the status of AR and androgen-producing enzymes during the process of metastasis to lymph nodes and cancer recurrence.

MATERIALS AND METHODS

We studied 2 series of patients with TNBC, one from Kumamoto University Hospital composed of 16 matched cases of primary and locally or distal recurrences and the other from Tohoku University Hospital examining 46 lymph node metastasis from 23 patients. In addition to studying concordance in AR expression, we also examined the interactions between AR and Ki-67 labeling index and AR and site of distal metastasis.

RESULTS

In both series, AR status was concordant between primary and recurrent/metastatic disease, but coordinated expression of AR and androgenic enzymes was lost during the process. The inverse association between AR and Ki-67, previously reported in invasive ductal carcinoma (IDC), was markedly potentiated in both lymph node and recurrent cancers. In addition, AR expression appeared to have little effect on visceral metastasis but was associated directly with bone metastasis and inversely with brain metastasis.

CONCLUSIONS

The results of our present study demonstrated that AR remained in the majority of metastatic samples from AR-positive primary TNBCs and that AR manipulation could be exploited in the metastatic settings of TNBC.

Predictive Biomarker Profiling of > 6000 Breast Cancer Patients Shows Heterogeneity in TNBC, With Treatment Implications

BACKGROUND

Triple-negative breast cancer (TNBC) is an aggressive disease without established targeted treatment options for patients with metastatic disease. This study was undertaken to evaluate potentially actionable biomarkers in a large cohort of TNBC and compare them with non-TNBCs.

MATERIALS AND METHODS

We evaluated 6341 (2111 TNBC and 4230 non-TNBC) breast cancer samples at a central laboratory for biomarkers of potential drug response across multiple platforms, including gene sequencing, protein expression, and gene copy number.

RESULTS

TNBC expresses androgen receptor (AR) in a significantly (P < .05) lower percentage of cases (17%) than hormone receptor (HR)-positive and human epidermal growth factor receptor 2 (HER2)-positive breast carcinomas (59% and 79%, respectively), and gene comutations were differentially associated with AR-positive versus AR-negative cases. Higher AR expression levels in TNBC predicted for lower Ki-67 levels. Seventy percent of TNBC harbored a phosphatidylinositol-4,5-bisphosphate 3-kinase, catalytic subunit alpha (PIK3CA), v-akt murine thymoma viral oncogene homolog 1 (AKT1), or phosophatase and tensin homolog (PTEN) aberration. TNBC patients had a significantly lower PIK3CA mutation rate (13%) than all other subtypes (P < .05) and a higher tumor protein p53 (TP53) mutation rate (64%) than the estrogen receptor (ER)-positive cases (approximately 30%; P < .05). Topoisomerase 2 (TOP2A) amplification was observed in 1.3% of TNBC and in 1.6% of HER2-negative, HR-positive cancers; in contrast, HER2-positive, HR-negative or HR-positive cancers exhibited TOP2A amplification in 19% and 40% of cases, respectively (P <.05).

CONCLUSION

Multi-platform molecular profiling identifies subgroups of TNBC with different biomarker profiles, suggesting numerous potentially targetable alterations in TNBC. TNBC is further characterized by different gene mutations and proliferative activity relative to AR expression, highlighting a need for comprehensive pathologic examination with potential to develop different, individualized treatment options.

The intracrinology of breast cancer

The importance of intracrinology, or in situ production of steroids from circulating precursors, in breast cancer has been firmly established in estrogen actions on postmenopausal patients. Expression levels of various steroid synthesizing and/or metabolizing enzymes have been examined in human breast cancer tissues by a number of groups. The enzymes examined include those capable of converting circulating DHEA-S to sex steroids (STS and 3βHSDΔ4-5 isomerase), the group of enzymes that modulate the strength of both androgens and estrogens (17βHSD family) as well as the androgenic 5αR enzymes and the estrogenic aromatase enzyme. In addition to these DHEA-related metabolism pathways, other intracrine pathways involving progesterone and cholesterol have also been examined. Some risk factors of breast cancer development, including obesity, have also been postulated to interact with steroid metabolising pathways. In this review, we aimed to summarise the current state of knowledge regarding intracrine metabolism including expression levels of various enzymes and receptors, focusing particularly upon the importance of the production of biologically potent steroids from circulating sulfated precursors such as DHEA-S. In addition, we attempted to summarise the factors, both steroidal and non-steroidal, involved in the regulation of these enzymes and propose future directions for research in this particular field. The concept of intracrinology was first proposed over 20 years ago but there still remain many unanswered questions which could open new horizons for the understanding of intracrine metabolism in the breast. This article is part of a Special Issue entitled 'Essential role of DHEA'.

Intratumoral androgen metabolism and actions in invasive lobular carcinoma of the breast

Invasive lobular carcinoma (ILC) accounts for approximately 10% of all breast carcinomas and is characterized by higher levels of androgen receptor (AR) compared to invasive ductal carcinoma (IDC). Despite this potentially androgen-responsive environment, the combined importance of AR and androgen metabolism in non-neoplastic lobules and lobular carcinoma remains unknown. Therefore, in this study, we evaluated the status of pivotal androgen-producing enzymes 17β-hydroxysteroid dehydrogenase type 5 (17βHSD5) and 5α-reductase type 1 (5αRed1) in 178 cases of ILC and surrounding histologically non-neoplastic lobular tissue using immunohistochemistry. Androgen receptor prevalence was higher but androgenic enzymes lower in ILC than non-neoplastic lobules. In ILC cases the status of 5αRed1 and 17βHSD5 was inversely correlated with tumor size (P = 0.0053) and nuclear grade (P = 0.0290), and significantly associated with better overall survival of the patients (P = 0.0059). Based on these findings, we hypothesized that androgen signaling could act as a tumor suppressor. As previous studies suggested that androgens might partially act by increasing levels of the estrogen inactivating enzyme 17β-hydroxysteroid dehydrogenase type 2 (17βHSD2) in IDC tissues, this was reasonably considered a potential mechanism of androgen actions. Significantly positive correlation was detected between the status of androgenic enzymes and 17βHSD2 (P < 0.0001) and intratumoral 17βHSD2 was inversely correlated with tumor size in ILC (P = 0.0075). These correlations suggest one protective mode of androgen action could be through modulation of estrogen metabolism. Results of our present study indicated that androgen-producing enzymes could play pivotal protective roles in AR-enriched ILC cases.

An activation of LC3A-mediated autophagy contributes to de novo and acquired resistance to EGFR tyrosine kinase inhibitors in lung adenocarcinoma

The development of therapeutic resistance to EGFR tyrosine kinase inhibitors (EGFR-TKIs, ie erlotinib or gefitinib) has been the major clinical problem when treating lung adenocarcinoma patients with these agents. However, its mechanisms have not necessarily been well studied to this date. Autophagy has been recently considered to play pivotal roles in escaping from the effects of anti-neoplastic agents. Therefore, in this study, we examined its roles in the development of resistance to EGFR-TKIs in lung adenocarcinoma. We first established erlotinib-resistant cell lines (PC9/ER) from parental PC9 cells by exposing the cells to erlotinib. In PC9/ER, autophagy-related LC3A expression came to be up-regulated and constitutive activation of LC3A-mediated autophagy became more pronounced through the process of acquiring therapeutic resistance. In addition, inhibition of LC3A or autophagy restores sensitivity to EGFR-TKIs in PC9/ER. LC3A was also activated at the transcriptional level in de novo resistant cells via demethylation of the MAP1LC3A gene. We then evaluated the status of LC3A in 169 lung adenocarcinoma patients using immunohistochemistry. LC3A immunoreactivity was only detected in carcinoma cells (89/169 patients), not in non-tumoural cells. In addition, LC3A immunoreactivity was significantly correlated with progression-free survival (p = 0.0039) and overall survival (p = 0.0040) of 35 patients treated with EGFR-TKIs. The results of our present study demonstrated that LC3A-mediated autophagy in carcinoma cells was involved in the development of resistance to EGFR-TKIs, and that LC3A could serve as a promising therapeutic target for overcoming resistance to EGFR-TKIs and a novel predictor of response to EGFR-TKIs in lung adenocarcinoma patients.

Complexities of androgen receptor signalling in breast cancer

While the clinical benefit of androgen-based therapeutics in breast cancer has been known since the 1940s, we have only recently begun to fully understand the mechanisms of androgen action in breast cancer. Androgen signalling pathways can have either beneficial or deleterious effects in breast cancer depending on the breast cancer subtype and intracellular context. This review discusses our current knowledge of androgen signalling in breast cancer, including the relationship between serum androgens and breast cancer risk, the prognostic significance of androgen receptor (AR) expression in different breast cancer subtypes and the downstream molecular pathways mediating androgen action in breast cancer cells. Intracrine androgen metabolism has also been discussed and proposed as a potential mechanism that may explain some of the reported differences regarding dichotomous androgen actions in breast cancers. A better understanding of AR signalling in this disease is critical given the current resurgence in interest in utilising contemporary AR-directed therapies for breast cancer and the need for biomarkers that will accurately predict clinical response.