Clinicopathological significance of prolactin receptor expression in colorectal carcinoma and corresponding metastases

The Potential Prognostic and Therapeutic Implications of Prolactin Receptor and Growth Hormone-releasing Hormone Receptor Expression in Uterine Leiomyosarcomas

The management of uterine leiomyosarcomas (uLMS) remains challenging. The rate of recurrence and metastasis is high, with 5-yr survival reaching only 40% to 50% in patients with tumor confined to the uterus (FIGO stage I or II). Prolactin receptor (PRLR) and growth hormone-releasing hormone receptor (GHRHR) have been implicated in the carcinogenesis of malignant tumors of the breast, endometrium, ovary, liver, and prostate. GHRHR antagonists inhibit in vitro growth of many human tumors and the expression of PRLR is associated with resistance to chemotherapy. The immunohistochemical expression of PRLR and GHRH in 24 primary and 2 recurrent uLMS was evaluated. Representative sections were stained with PRLR and GHRHR antibodies and immunoreactivity was calculated using H -score. The results were correlated with clinicopathologic data using Kaplan-Meier survival and multivariable Cox proportion hazard regression analyses. All tumors were positive for both markers with predominantly moderate to strong expression of PRLR (89%) and GHRHR (82%). Patients with tumors showing moderate to strong expression of PRLR were significantly less likely to achieve disease-free survival ( P =0.004) and significantly more likely to have a poor overall survival ( P =0.049). No significant difference in mean PRLR expression was found between tumors with higher mitotic counts (>20/10 hpf) and lower mitotic counts (20 or less/10 hpf). Furthermore, in 2 patients where the primary and recurrent tumors were tested, there was stronger expression of PRLR in the recurrence compared with the primary. This correlation was not found with GHRHR. Both PRLR and GHRHR may play a role in carcinogenesis in uLMS, as they do in other malignant neoplasms. To our knowledge, this study is the first evaluating the expression of these receptors in uLMS. Moderate or high expression of PRLR may serve as a prognostic marker associated with recurrences and increased mortality in uLMS patients.

Immunohistochemical localization of prolactin receptor (PRLR) to Hodgkin's and Reed-Sternberg cells of Hodgkin's lymphoma

Prolactin receptor (PRLR), a type-1 cytokine receptor, is overexpressed in a number of cancer types. It has attracted much attention for putative pro-oncogenic roles, which however, remains controversial in some malignancies. In this study, we reported the localization of PRLR to the Hodgkin's and Reed-Sternberg (HRS) cells of Hodgkin's lymphoma (HL), a neoplasm of predominantly B cell origin. Immunohistochemistry performed on 5-μm thick FFPE sections revealed expression of PRLR in HRS cells. Cellular immunofluorescence experiments showed that the HL-derived cell lines, Hs445, KMH2 and L428 overexpressed PRLR. The PRLR immunofluorescent signal was depleted after treating the cell lines with 10 μM of siRNA for 48 h. We also tested whether PRLR is involved in the growth of HL, in vitro. One-way analysis of variance (ANOVA) on cell growth data obtain from WST-1 cell proliferation assay and trypan blue exclusion assay and hemocytometry showed that siRNA-depletion of PRLR expression resulted in decreased growth in all three cell lines. These results offered only a short insight into the involvement of PRLR in HL. As a result, further investigation is required to decipher the precise role(s) of PRLR in the pathogenesis of HL.

Sex-related hormone receptor in laryngeal squamous cell carcinoma: correlation with androgen estrogen-ɑ and prolactin receptor expression and influence of prognosis

BACKGROUND

The expression and function of androgen receptors (AR) and estrogen receptor alpha (ER-ɑ) in laryngeal squamous cell carcinoma (LSCC) have remained controversial for decades. Prolactin receptor (PRLR) is a sex-related hormone, that has been rarely documented in terms of expression or function compared with data on other hormone receptors in laryngeal carcinoma.

METHODS

This study reports on immunohistochemical and reverse transcription-polymerase chain reaction (RT-PCR) analysis of tumour tissue and adjacent normal tissue in 96 patients with LSCC (82 males and 14 females). The expression levels of the receptors were related to clinicopathologic parameters and survival data.

RESULTS

At both protein and mRNA levels, the expression level of AR, ER-ɑ, and PRLR was much higher in LSCC than in adjacent normal tissues (p < .05). Among them, higher PRLR expression in tumour tissues tended to have a significantly poorer survival rate (p = .03) for patients with LSCC. Furthermore, higher expression of ER-ɑ in tumours was correlated with higher expression level of PRLR (r = .823, p = .03).

CONCLUSION

The findings of this study indicate that the sex-related hormone receptors play an important role in the development of LSCC. The PRLR represents a novel prognosticator, because of its negative effect on survival and its interaction with ER-ɑ.

Expression of epithelial-mesenchymal transition-related genes increases with copy number in multiple cancer types

Epithelial-mesenchymal transition (EMT) is a cellular process through which epithelial cells transform into mesenchymal cells. EMT-implicated genes initiate and promote cancer metastasis because mesenchymal cells have greater invasive and migration capacities than epithelial cells. In this pan-cancer analysis, we explored the relationship between gene expression changes and copy number variations (CNVs) for EMT-implicated genes. Based on curated 377 EMT-implicated genes from the literature, we identified 212 EMT-implicated genes associated with more frequent copy number gains (CNGs) than copy number losses (CNLs) using data from The Cancer Genome Atlas (TCGA). Then by correlating these CNV data with TCGA gene expression data, we identified 71 EMT-implicated genes with concordant CNGs and gene up-regulation in 20 or more tumor samples. Of those, 14 exhibited such concordance in over 110 tumor samples. These 14 genes were predominantly apoptosis regulators, which may implies that apoptosis is critical during EMT. Moreover, the 71 genes with concordant CNG and up-regulation were largely involved in cellular functions such as phosphorylation cascade signaling. This is the first observation of concordance between CNG and up-regulation of specific genes in hundreds of samples, which may indicate that somatic CNGs activate gene expression by increasing the gene dosage.

Phase I Study of the Prolactin Receptor Antagonist LFA102 in Metastatic Breast and Castration-Resistant Prostate Cancer

LESSONS LEARNED

Despite evidence for a role for prolactin signaling in breast and prostate tumorigenesis, a prolactin receptor-binding monoclonal antibody has not produced clinical efficacy.Increased serum prolactin levels may be a biomarker for prolactin receptor inhibition.Results from the pharmacokinetic and pharmacodynamics (PD) studies suggest that inappropriately long dosing intervals and insufficient exposure to LFA102 may have resulted in lack of antitumor efficacy.Based on preclinical data, combination therapy of LFA102 with those novel agents targeting hormonal pathways in metastatic castration-resistant prostate cancer and metastatic breast cancer is promising.Given the PD evidence of prolactin receptor blockade by LFA102, this drug has the potential to be used in conditions such as hyperprolactinemia that are associated with high prolactin levels.

BACKGROUND

Prolactin receptor (PRLR) signaling is implicated in breast and prostate cancer. LFA102, a humanized monoclonal antibody (mAb) that binds to and inhibits the PRLR, has exhibited promising preclinical antitumor activity.

METHODS

Patients with PRLR-positive metastatic breast cancer (MBC) or metastatic castration-resistant prostate cancer (mCRPC) received doses of LFA102 at 3-60 mg/kg intravenously once every 4 weeks. Objectives were to determine the maximum tolerated dose (MTD) and/or recommended dose for expansion (RDE) to investigate the safety/tolerability of LFA102 and to assess pharmacokinetics (PK), pharmacodynamics (PD), and antitumor activity.

RESULTS

A total of 73 patients were enrolled at 5 dose levels. The MTD was not reached because of lack of dose-limiting toxicities. The RDE was established at 60 mg/kg based on PK and PD analysis and safety data. The most common all-cause adverse events (AEs) were fatigue (44%) and nausea (33%) regardless of relationship. Grade 3/4 AEs reported to be related to LFA102 occurred in 4% of patients. LFA102 exposure increased approximately dose proportionally across the doses tested. Serum prolactin levels increased in response to LFA102 administration, suggesting its potential as a biomarker for PRLR inhibition. No antitumor activity was detected.

CONCLUSION

Treatment with LFA102 was safe and well tolerated, but did not show antitumor activity as monotherapy at the doses tested.

A Novel Nectin-mediated Cell Adhesion Apparatus That Is Implicated in Prolactin Receptor Signaling for Mammary Gland Development

Mammary gland development is induced by the actions of various hormones to form a structure consisting of collecting ducts and milk-secreting alveoli, which comprise two types of epithelial cells known as luminal and basal cells. These cells adhere to each other by cell adhesion apparatuses whose roles in hormone-dependent mammary gland development remain largely unknown. Here we identified a novel cell adhesion apparatus at the boundary between the luminal and basal cells in addition to desmosomes. This apparatus was formed by the trans-interaction between the cell adhesion molecules nectin-4 and nectin-1, which were expressed in the luminal and basal cells, respectively. Nectin-4 of this apparatus further cis-interacted with the prolactin receptor in the luminal cells to enhance the prolactin-induced prolactin receptor signaling for alveolar development with lactogenic differentiation. Thus, a novel nectin-mediated cell adhesion apparatus regulates the prolactin receptor signaling for mammary gland development.

Reporting in studies of protein biomarkers of prognosis in colorectal cancer in relation to the REMARK guidelines

PURPOSE

The REMARK guidelines give authors comprehensive and specific advice on the complete and transparent reporting of studies of prognostic tumor markers. The aim of this study was to use the REMARK guidelines to evaluate the quality of reporting in a sample of studies assessing tissue-based protein markers for survival after resection of colorectal cancer.

EXPERIMENTAL DESIGN

Eighty pertinent articles were scored according to their conformity to 26 items derived from the REMARK criteria.

RESULTS

Overall, on a scale of adequacy of reporting that potentially ranged from 26 to 78, the median for these studies was 60 (interquartile range 54-64) and several criteria were adequately covered in a large proportion of studies. However, others were either not dealt with or inadequately covered, including description of the study design (35%), definition of survival endpoints (48%), adjuvant therapy (54%), follow-up procedures and time (59%), neoadjuvant therapy (63%), inclusion/exclusion criteria (73%), multivariable modeling methods and results (74%), and discussion of study limitations (85%).

CONCLUSIONS AND CLINICAL RELEVANCE

Inadequacies in presentation militate against comparability among protein marker studies and undermine the generalizability of their findings. The quality of reporting could be improved if journal editors were to require authors to ensure that their work satisfied the REMARK criteria.

Prolactin and prolactin receptor expression in cervical intraepithelial neoplasia and cancer

Prolactin receptor (PRLR) overexpression could play a role in tumorigenesis. The aim of this study was to determine prolactin (PRL) and PRLR expression in biopsies from patients with precursor lesions and uterine cervical cancer. PRLR expression was analyzed in 63 paraffin-embedded biopsies of uterine cervical tissue. In total, eleven low-grade squamous intraepithelial lesions (LSIL), 23 high-grade squamous intraepithelial lesions (HSIL), 21 uterine cervical cancers (UCC) and 8 normal epithelium (NE) were examined using immunoperoxidase staining and Western blot analysis. Additionally, PRL expression was identified in human cervical cancer serum and tissues. The PRLR expression was found to be significantly increased in cervical cancer in comparison with normal tissue and precursor lesions (P < 0.0003). The presence of the long isoform of the PRLR was observed only in cervical cancer tissues. Serum PRL levels were normal in all samples and local prolactin expression was similar in precursor lesions and cervical cancer by Western blot analysis. Our data suggest a possible role for PRLR in the progression of cervical cancer.

Prolactin signaling enhances colon cancer stemness by modulating Notch signaling in a Jak2-STAT3/ERK manner

Prolactin (PRL) is a secretory cytokine produced by various tissues. Binding to the cognate PRL receptor (PRLR), it activates intracellular signaling via janus kinase (JAK), extracellular signal-regulated kinase (ERK) and signal transducer and activator of transcription (STAT) proteins. PRL regulates diverse activities under normal and abnormal conditions, including malignancies. Previous clinical data suggest serum PRL levels are elevated in colorectal cancer (CRC) patients. In this study, we first determined the expression of PRL and PRLR in colon cancer tissue and cell lines. Higher levels of PRLR expression were observed in the cancer cells and cell lines compared with normal colonic epithelial cells. Incubation of colon cancer cells with PRL-induced JAK2, STAT3 and ERK1/2 phosphorylation and increased expression of Jagged 1, which is a Notch-1 receptor ligand. Notch signaling regulates CRC stem cell population. We observed increased accumulation of the cleaved/active form of Notch-1 receptor (Notch intracellular domain) and increased expression of Notch responsive genes HEY1, HES1 and stem cell marker genes DCLK1, LGR5, ALDH1 and CD44. Finally, inhibiting PRL induced JAK2-STAT3 and JAK2-ERK1/2 using AG490 and PD98059, respectively, leads to complete abrogation of Notch signaling, suggesting a role for this pathway in regulating CRC stem cells. Together, our results demonstrate that cytokine signaling induced by PRL is active in colorectal cancers and may provide a novel target for therapeutic intervention.

No-cost manual method for preparation of tissue microarrays having high quality comparable to semiautomated methods

Manual tissue microarray (TMA) construction had been introduced to avoid the high cost of automated and semiautomated techniques. The cheapest and simplest technique for constructing manual TMA was that of using mechanical pencil tips. This study was carried out to modify this method, aiming to raise its quality to reach that of expensive ones. Some modifications were introduced to Shebl's technique. Two conventional mechanical pencil tips of different diameters were used to construct the recipient blocks. A source of mild heat was used, and blocks were incubated at 38°C overnight. With our modifications, 3 high-density TMA blocks were constructed. We successfully performed immunostaining without substantial tissue loss. Our modifications increased the number of cores per block and improved the stability of the cores within the paraffin block. This new, modified technique is a good alternative for expensive machines in many laboratories.

Prolactin receptor in primary hyperparathyroidism--expression, functionality and clinical correlations

Background

Primary hyperparathyroidism (PHPT) is an endocrine disorder most commonly affecting women, suggesting a role for female hormones and/or their receptors in parathyroid adenomas. We here investigated the prolactin receptor (PRLr) which is associated with tumours of the breast and other organs.

Methodology/Principal Findings

PRLr expression was investigated in a panel of 37 patients with sporadic parathyroid tumours and its functionality in cultured parathyroid tumour cells. In comparison with other tissues and breast cancer cells, high levels of prolactin receptor gene (PRLR) transcripts were demonstrated in parathyroid tissues. PRLr products of 60/70 kDa were highly expressed in all parathyroid tumours. In addition varying levels of the 80 kDa PRLr isoform, with known proliferative activity, were demonstrated. In parathyroid tumours, PRLr immunoreactivity was observed in the cytoplasm (in all cases, n = 36), cytoplasmic granulae (n = 16), the plasma membrane (n = 12) or enlarged lysosomes (n = 4). In normal parathyroid rim (n = 28), PRLr was uniformly expressed in the cytoplasm and granulae. In in vitro studies of short-term cultured human parathyroid tumour cells, prolactin stimulation was associated with significant transcriptional changes in JAK/STAT, RIG-I like receptor and type II interferon signalling pathways as documented by gene expression profiling. Moreover, PRLR gene expression in parathyroid tumours was inversely correlated with the patients’ plasma calcium levels.

Conclusions

We demonstrate that the prolactin receptor is highly abundant in human parathyroid tissues and that PRLr isoforms expression and PRLr subcellular localisation are altered in parathyroid tumours. Responsiveness of PRLr to physiological levels of prolactin was observed in the form of increased PTH secretion and altered gene transcription with significant increase of RIG-I like receptor, JAK-STAT and Type II interferon signalling pathways. These data suggest a role of the prolactin receptor in parathyroid adenomas.

Increased expression of the prolactin receptor is associated with malignant laryngeal tumors

The altered expression of the prolactin receptor (PRLR) has been associated with the development of various types of cancer, particularly breast, prostate and endometrial cancer. However, in laryngeal tumors, the expression of PRLR has not yet been documented. The aim of this study was to determine the expression and localization of PRLR in laryngeal cancer (LC) in comparison with recurrent respiratory papillomatosis (RRP). PRLR expression was analyzed in 48 paraffin-embedded tissues (18 RRP and 30 laryngeal cancer tissues) by immunoperoxidase staining. Furthermore, PRLR expression was evaluated in ten samples from each group by Western blot analysis and quantitative real-time PCR. PRLR was observed in all laryngeal tumors at different intensities. PRLR overexpression was significantly associated (P<0.005) with LC. The staining pattern was homogeneous, mainly cytoplasmic, and confined to the tumor area. We found increased expression of different isoforms in LC in comparison with RRP. Our results suggest a possible role of PRL/PRLR in the development of LC. PRLR may be useful as a target for further investigations in laryngeal tissues.

Prolactin receptor is a negative prognostic factor in patients with squamous cell carcinoma of the head and neck

Background:

The influence of human prolactin (hPRL) on the development of breast and other types of cancer is well established. Little information, however, exists on the effects of hPRL on squamous cell carcinomas of the head and neck (SCCHNs).

Methods:

In this study, we evaluated prolactin receptor (PRLR) expression in SCCHN cell lines and assessed by immunohistochemistry the expression in 89 patients with SCCHNs. The PRLR expression was correlated with clinicopathological characteristics as well as clinical outcome. The effect of hPRL treatment on tumour cell growth was evaluated in vitro.

Results:

Immunoreactivity for PRLR was observed in 85 out of 89 (95%) tumours. Multivariate COX regression analysis confirmed high levels of PRLR expression (>25% of tumour cells) to be an independent prognostic factor with respect to overall survival (HR=3.70, 95% CI: 1.14–12.01; P=0.029) and disease-free survival (P=0.017). Growth of PRLR-positive cancer cells increased in response to hPRL treatment.

Conclusion:

Our data indicate that hPRL is an important growth factor for SCCHN. Because of PRLR expression in a vast majority of tumour specimens and its negative impact on overall survival, the receptor represents a novel prognosticator and a promising drug target for patients with SCCHNs.

Role of the growth hormone-IGF-1 axis in cancer

A substantial body of evidence supports a role for the growth hormone (GH)-IGF-1 axis in cancer incidence and progression. This includes epidemiological evidence relating elevated plasma IGF-1 to cancer incidence as well as a lack of cancers in GH/IGF-1 deficiency. Rodent models lacking GH or its receptor are strikingly resistant to the induction of a wide range of cancers, and treatment with the GH antagonist pegvisomant slows tumor progression. While GH receptor expression is elevated in many cancers, autocrine GH is present in several types, and overexpression of autocrine GH can induce cell transformation. While the mechanism of autocrine action is not clear, it does involve both STAT5 and STAT3 activation, and probably nuclear translocation of the GH receptor. Development of a more potent GH receptor antagonist or secretion inhibitor is warranted for cancer therapy.