Inflammation-induced PELP1 expression promotes tumorigenesis by activating GM-CSF paracrine secretion in the tumor microenvironment.

The inflammatory tumor microenvironment has been implicated as a major player fueling tumor progression and an enabling characteristic of cancer, proline, glutamic acid, and leucine-rich protein 1 (PELP1) is a novel nuclear receptor coregulator that signals across diverse signaling networks, and its expression is altered in several cancers. However, investigations to find the role of PELP1 in inflammation-driven oncogenesis are limited. Molecular studies here, utilizing macrophage cell lines and animal models upon stimulation with lipopolysaccharide (LPS) or necrotic cells, showed that PELP1 is an inflammation-inducible gene. Studies on the PELP1 promoter and its mutant identified potential binding of c-Rel, an NF-κB transcription factor subunit, to PELP1 promoter upon LPS stimulation in macrophages. Recruitment of c-Rel onto the PELP1 promoter was validated by chromatin immunoprecipitation, further confirming LPS mediated PELP1 expression through c-Rel-specific transcriptional regulation. Macrophages that overexpress PELP1 induces granulocyte-macrophage colony-stimulating factor secretion, which mediates cancer progression in a paracrine manner. Results from preclinical studies with normal-inflammatory-tumor progression models demonstrated a progressive increase in the PELP1 expression, supporting this link between inflammation and cancer. In addition, animal studies demonstrated the connection of PELP1 in inflammation-directed cancer progression. Taken together, our findings provide the first report on c-Rel-specific transcriptional regulation of PELP1 in inflammation and possible granulocyte-macrophage colony-stimulating factor-mediated transformation potential of activated macrophages on epithelial cells in the inflammatory tumor microenvironment, reiterating the link between PELP1 and inflammation-induced oncogenesis. Understanding the regulatory mechanisms of PELP1 may help in designing better therapeutics to cure various inflammation-associated malignancies.

Altered Expression of ESR1, ESR2, PELP1 and c-SRC Genes Is Associated with Ovarian Cancer Manifestation.

Ovarian cancer remains the leading cause of death due to gynecologic malignancy. Estrogen-related pathways genes, such as estrogen receptors (ESR1 and ESR2) and their coregulators, proline-, glutamic acid-, and leucine-rich protein 1 (PELP1), and proto-oncogene tyrosine-protein kinase c-Src (SRC) are involved in ovarian cancer induction and development, still they require in-depth study. In our study, tissue samples were obtained from 52 females of Caucasian descent (control group without cancerous evidence (n = 27), including noncancerous benign changes (n = 15), and the ovarian carcinoma (n = 25)). Using quantitative analyses, we investigated ESRs, PELP1, and SRC mRNA expression association with ovarian tumorigenesis. Proteins' presence and their location were determined by Western blot and immunohistochemistry. Results showed that PELP1 and SRC expression levels were found to differ in tissues of different sample types. The expression patterns were complex and differed in the case of ovarian cancer patients compared to controls. The most robust protein immunoreactivity was observed for PELP1 and the weakest for ESR1. The expression patterns of analyzed genes represent a potentially interesting target in ovarian cancer biology, especially PELP1. This study suggests that specific estrogen-mediated functions in the ovary and ovary-derived cancer might result from different local interactions of estrogen with their receptors and coregulators.

Death domain-associated protein (DAXX) expression is associated with poor survival in metastatic high-grade serous carcinoma.

The objective of this study was to analyze the expression and clinical role of mitosis regulators α-thalassemia/mental retardation syndrome X-linked (ATRX) and death-domain-associated protein (DAXX) in metastatic high-grade serous carcinoma (HGSC). ATRX and DAXX protein expression by immunohistochemistry was analyzed in 400 HGSC effusions. DAXX expression was additionally studied in 15 cancer cell lines, including 4 ovarian carcinoma lines, and in 81 of the 400 HGSC effusions using Western blotting. ATRX and DAXX were expressed in HGSC cells in 386/400 (96%) and 348/400 (87%) effusions, respectively. Western blotting showed DAXX expression in all 15 cell lines and in 70/81 (86%) HGSC effusions. DAXX expression by immunohistochemistry was higher in pleural compared to peritoneal effusions (p = 0.006) and in post-chemotherapy compared to pre-chemotherapy effusions (p = 0.004), and its expression was significantly associated with poor overall survival in univariate of the entire cohort (p = 0.014), as well as analysis limited to chemo-naïve effusions tapped at diagnosis (p = 0.038). The former association retained its prognostic role in Cox multivariate survival analysis (p = 0.011). ATRX expression was unrelated to clinicopathologic parameters or survival. In conclusion, DAXX is associated with disease progression and could be a prognostic marker in metastatic HGSC. Silencing this molecule may have therapeutic relevance in this cancer.

Telomere length alterations and ATRX/DAXX loss in pituitary adenomas.

Telomeres are nucleoprotein complexes located at the termini of eukaryotic chromosomes that prevent exonucleolytic degradation and end-to-end chromosomal fusions. Cancers often have critically shortened, dysfunctional telomeres contributing to genomic instability. Telomere shortening has been reported in a wide range of precancerous lesions and invasive carcinomas. However, the role of telomere alterations, including the presence of alternative lengthening of telomeres (ALT), has not been studied in pituitary adenomas. Telomere length and the presence of ALT were assessed directly at the single cell level using a telomere-specific fluorescence in situ hybridization assay in tissue microarrays. Tumors were characterized as either ALT-positive or having short, normal, or long telomere lengths and then these categories were compared with clinicopathological characteristics. ATRX and DAXX expression was studied through immunohistochemistry. We characterized a discovery set of 106 pituitary adenomas including both functional and nonfunctional subsets (88 primary, 18 recurrent). Telomere lengths were estimated and we observed 64 (59.4%) cases with short, 39 (36.8%) cases with normal, and 0 (0%) cases with long telomeres. We did not observe significant differences in the clinicopathological characteristics of the group with abnormally shortened telomeres compared to the group with normal telomeres. However, three pituitary adenomas were identified as ALT-positive of which two were recurrent tumors. Two of these three ALT-positive cases had alterations in either of the chromatin remodeling proteins, ATRX and DAXX, which are routinely altered in other ALT-positive tumor subtypes. In a second cohort of 32 recurrent pituitary adenomas from 22 patients, we found that the tumors from 36% of patients (n = 8) were ALT-positive. This study demonstrates that short telomere lengths are prevalent in pituitary adenomas and that ALT-positive pituitary adenomas are enriched in recurrent disease.

TLE1 expression fails to distinguish between synovial sarcoma, atypical fibroxanthoma, and dermatofibrosarcoma protuberans.

Transducin-like enhancer of split 1 (TLE1) belongs to the Groucho/TLE/Grg family. It functions as a transcriptional corepressor and is widely used as a biomarker of synovial sarcoma (SS). Within the skin, atypical fibroxanthoma (AFX) and dermatofibrosarcoma protuberans (DFSP) often enter the histopathologic differential diagnosis. TLE1 expression has not been evaluated in these neoplasms. We examined archived tissues sections from the surgical pathology files from 10 adult patients diagnosed with AFX and 10 adult patients diagnosed with DFSP. We found nuclear staining in 10 of 10 AFX and 2 of 10 DFSP. We also noticed three patterns of staining in AFX: predominantly spindle component, predominantly epithelioid component, or mixed pattern of both epithelioid and spindle components. The group with the predominantly spindle pattern expressed the strongest nuclear TLE1 staining. In the DFSP group, one lesion demonstrated staining of epithelioid cells, with strong, diffuse nuclear TLE 1 expression, and the second lesion stained only the spindled cells, with weak nuclear TLE1 marking. In conclusion, TLE1, while a sensitive marker for SS, is not specific. A wide range of cutaneous spindle cell neoplasms also express TLE1. AFX and DFSP should be added to this list. TLE1 might be added to a diagnostic panel in this differential diagnosis.

Reduced DAXX Expression Is Associated with Reduced CD24 Expression in Colorectal Cancer.

The presence of an activating mutation of the Wnt/ß-catenin signaling pathway is found in ~90% of colorectal cancer (CRC) cases. Death domain-associated protein (DAXX), a nuclear protein, interacts with ß-catenin in CRC cells. We investigated DAXX expression in 106 matched sample pairs of CRC and adjacent normal tissue by Western blotting. This study evaluated DAXX expression and its clinical implications in CRC. The results revealed that DAXX expression was significantly lower in the patients with the positive serum carcinoembryonic antigen (CEA) screening results compared to the patients with negative CEA screening levels (p < 0.001). It has been reported that CD24 is a Wnt target in CRC cells. Here, we further revealed that DAXX expression was significantly correlated with CD24 expression (rho = 0.360, p < 0.001) in 106 patients. Consistent with this, in the CEA-positive subgroup, of which the carcinomas expressed DAXX at low levels, they were significantly correlated with CD24 expression (rho = 0.461, p < 0.005). Therefore, reduced DAXX expression is associated with reduced CD24 expression in CRC. Notably, in the Hct116 cells, DAXX knockdown using short-hairpin RNA against DAXX (shDAXX) not only caused significant cell proliferation, but also promoted metastasis. The DAXX-knockdown cells also demonstrated significantly decreased CD24 expression, however the intracellular localization of CD24 did not change. Thus, DAXX might be considered as a potential regulator of CD24 or ß-catenin expression, which might be correlated with proliferative and metastatic potential of CRC.

PELP1 is a novel oncogene in gastric tumorigenesis and negatively regulated by miR-15 family microRNAs.

BACKGROUD: Gastric cancer (GC) is one of the leading causes of cancer-related death in East Asia and some South American countries, but its mechanism has not been clarified clearly. Proline-, glutamic acid-, and leucine-rich protein-1 (PELP1), a co-regulatory molecule of estrogen receptor α (ER α), is up-regulated in series of cancers such as endometrial carcinoma, ovarian cancer, colorectal cancer, breast cancer, and non-small cell lung cancer. However, PELP1's role in GC is still obscure, and its aberrant expression in cancers also remains to be explained. METHODS: Immunohistochemical staining and Real-time PCR were used to compare the expression level of PELP1 in GC tissues and adjacent tissues. Western blot was used to detect the expression of PELP1 in cell lines. Kaplan-meier analysis and chi-square test were applied to evaluate the potential of PELP1 to function as a cancer biomarker. RNA interference was used to inhibit PELP1 expression in GC cells, followed by detecting cell proliferation, apoptosis, migration and invasion. Luciferase assay was conducted to validate whether miR-15 family members can directly target PELP1. RESULTS: In this study, we validated that PELP1 was significantly up-regulated in GC samples and cell lines. It was also demonstrated that the up-regulation of PELP1 was associated with several clinicopathologic features such as tumor diameter (P< 0.001), serum CEA level (P= 0.034), and lymphatic metastasis (P= 0.0009) of GC patients, and its high expression was correlated with shorter disease-free survival and overall survival of the patients. Knockdown of PELP1 remarkably arrested the proliferationï» migration and invasion, while promoted apoptosis. We also confirmed that miR-15 family microRNAs, most of which were down-regulated and tumor suppressor in cancers, were posttranscriptional regulators of PELP1. CONCLUSION: In conclusion, we demonstrated that PELP1 was an oncogene of GC associated with patients' prognosis and miR-15 family members contributed to its aberrant expression in cancers.

Metformin induces human esophageal carcinoma cell pyroptosis by targeting the miR-497/PELP1 axis.

Evasion of apoptosis is a major contributing factor to the development of chemo- and radiotherapy resistance. Therefore, activation of non-apoptotic programmed cell death (PCD) could be an effective alternative against apoptosis-resistant cancers. In this study, we demonstrated in vitro and in vivo that metformin can induce pyroptosis, a non-apoptotic PCD, in esophageal squamous cell carcinoma (ESCC), a commonly known chemo-refractory cancer, especially at its advanced stages. Proline-, glutamic acid- and leucine-rich protein-1 (PELP1) is a scaffolding oncogene and upregulated PELP1 in advanced stages of ESCC is highly associated with cancer progression and patient outcomes. Intriguingly, metformin treatment leads to gasdermin D (GSDMD)-mediated pyroptosis, which is abrogated by forced expression of PELP1. Mechanistically, metformin induces pyroptosis of ESCC by targeting miR-497/PELP1 axis. Our findings suggest that metformin and any other pyroptosis-inducing reagents could serve as alternative treatments for chemo- and radiotherapy refractory ESCC or other cancers sharing the same pyroptosis mechanisms.

Chromodomain Y-like Protein-Mediated Histone Crotonylation Regulates Stress-Induced Depressive Behaviors.

BACKGROUND: Major depressive disorder is a prevalent and life-threatening illness in modern society. The susceptibility to major depressive disorder is profoundly influenced by environmental factors, such as stressful lifestyle or traumatic events, which could impose maladaptive transcriptional program through epigenetic regulation. However, the underlying molecular mechanisms remain elusive. Here, we examined the role of histone crotonylation, a novel type of histone modification, and chromodomain Y-like protein (CDYL), a crotonyl-coenzyme A hydratase and histone methyllysine reader, in this process. METHODS: We used chronic social defeat stress and microdefeat stress to examine the depressive behaviors. In addition, we combined procedures that diagnose behavioral strategy in male mice with histone extraction, viral-mediated CDYL manipulations, RNA sequencing, chromatin immunoprecipitation, Western blot, and messenger RNA quantification. RESULTS: The results indicate that stress-susceptible rodents exhibit lower levels of histone crotonylation in the medial prefrontal cortex concurrent with selective upregulation of CDYL. Overexpression of CDYL in the prelimbic cortex, a subregion of the medial prefrontal cortex, increases microdefeat-induced social avoidance behaviors and anhedonia in mice. Conversely, knockdown of CDYL in the prelimbic cortex prevents chronic social defeat stress-induced depression-like behaviors. Mechanistically, we show that CDYL inhibits structural synaptic plasticity mainly by transcriptional repression of neuropeptide VGF nerve growth factor inducible, and this activity is dependent on its dual effect on histone crotonylation and H3K27 trimethylation on the VGF promoter. CONCLUSIONS: Our results demonstrate that CDYL-mediated histone crotonylation plays a critical role in regulating stress-induced depression, providing a potential therapeutic target for major depressive disorder.

The Utility of NKX2.2 and TLE1 Immunohistochemistry in the Differentiation of Ewing Sarcoma and Synovial Sarcoma.

Although molecular testing can definitively distinguish Ewing sarcoma (EWS) from synovial sarcoma (SS) it is frequently desirable to provide a confident preliminary diagnosis before such analysis can be completed. Recently, the nuclear markers NKX2.2 and TLE1 have been shown to have good sensitivity but imperfect specificity, respectively, for EWS and SS. However, the performance of these markers has not been extensively evaluated within this specific differential diagnosis. This study performed NKX2.2, TLE1, and CD99 immunohistochemistry in a group of EWS and SSs confirmed by reverse transcription-polymerase chain reaction to evaluate the utility of these novel markers in this context. NKX2.2 staining was overall 75% sensitive and 91.7% specific for EWS and was never seen in SS. Although the specificity of TLE1 staining was impacted by antibody used, it was at best only 75% specific for SS. However, a lack of reactivity had a 100% negative predictive value against a SS diagnosis. Overall, immunohistochemistry for NKX2.2 and TLE1 can provide a useful first step in helping to distinguish EWS and SS.

miR-98-TXLNG1 (FIAT)/Sp7 function loop mediates osteoblast mineralization.

OBJECTIVE: To investigate the role of microRNAs (miRNAs) and its mechanism in osteoblast mineralization. MATERIALS AND METHODS: Real-time polymerase chain reaction (PCR), Northern Blot, and Western Blot were used to identify the expression mode of regulators. Overexpression and down-regulation experiments were carried out to study the role of miR-98 and interactions between regulators. Bioinformatics calculation and luciferase reporter assay were used to prove the target gene. Electrophoretic mobility shift assay (EMSA), chromatin immunoprecipitation (CHIP), and promoter luciferase reporter assay confirmed the relationship between the regulator and the promoter of miR-98. RESULTS: MiR-98 was up-regulated during osteoblast mineralization. Overexpression of miR-98 promoted osteoblast mineralization. Factor inhibiting activating transcription factor 4 (ATF4)-mediated transcription (FIAT), a negative regulator of osteoblast differentiation, was confirmed to be a target of miR-98. As a motivator in osteoblast mineralization, Sp7 transcription factor 7 (Sp7) promoted miR-98 transcription by a combination on the promoter region. CONCLUSIONS: Our study showed that miR-98 was an important regulator in osteoblast mineralization and miR-98 carried out its function through a novel miR-98-FIAT/Sp7 regulatory loop. It provides new insights into the roles of miRNAs in osteoblast mineralization.

Expression of oestrogen receptors (GPER, ESR1, ESR2) in human ductuli efferentes and proximal epididymis.

Oestrogen targeting in the human genital ducts is still not well-known. In fact, to date, the localization of oestrogen receptors, ESR1 and ESR2, is controversial and the presence of the membrane oestrogen receptor GPER (G protein-coupled oestrogen receptor) is unexplored. This study has investigated the expression of GPER, ESR1, ESR2 in human ductuli efferentes and proximal caput epididymis by immunohistochemistry and Western blot analysis. Furthermore, the presence of PELP1 (proline-glutamic acid-leucine-rich protein 1), a co-regulator of the oestrogen receptors, was also evaluated. In ductuli efferentes, GPER and ESR1 were clearly localized in all epithelial cells, while ESR2 was evidenced only in ciliated cells. Conversely, the epithelial cells of proximal caput epididymis revealed moderate GPER immunoreactivity, the absence of ERS1 and the occasional presence of ESR2. Furthermore, PELP1 was observed in ciliated cells of ductuli efferentes and in principal cells of proximal caput epididymis. Therefore, this study firstly demonstrated the expression of GPER in human male genital ducts, revealing a new mediator of oestrogen action in these anatomical sites. ESR1 and ESR2 were differentially localized in the two genital tracts together with PELP1, but cell sites of ERs and their co-regulator were not homogeneous. So, a different regional/cellular association of GPER with the classical oestrogen receptors was highlighted, suggesting that oestrogen action could be mediated by GPER, ESR1, ESR2 in ductuli efferentes, while by GPER and, occasionally by ESR2, in proximal caput epididymis. This study suggests that the specific oestrogen-mediated functions in human genital ducts might result from the different local interactions of oestrogens with oestrogen receptors and their co-regulators.

Epigenetic modification of TLE1 induce abnormal differentiation in diabetic mice intestinal epithelium.

The intestinal epithelium cells (IECs) in diabetes mellitus (DM) patients have been proven to be abnormally differentiated. During the differentiation of IECs, epigenetic modification acts as an important regulator. In this study, we aimed to examine the epigenetic alteration of Transducin-like Enhancer of Split 1 (TLE1), a multitask transcriptional co-repressor, contributing to the differentiation homeostasis in IECs of DM mice. The IECs of type 2 diabetic mice model were isolated and collected. Methylation states of whole genomic DNA promoter regions were investigated by microarray. Methylated-specific PCR was used to detect the methylation state of TLE1 promoter in DM mice IECs. The expression of TLE1, Hes1, and differentiated cell markers were measured through real-time PCR, Western blots, and immunohistochemistry; by transfection assay, TLE1 or Hes1 was independently down-regulated in intestinal epithelium cell line, IEC-6. Subsequent modulation on TLE1, Hes1, and differentiated intestinal cell markers were detected. Global gene promoter regions in DM intestinal epithelium were less methylated comparing to normal control. The expression of TLE1 was significantly increased via hypomethylated activation in DM mice IECs. Hes1 was significantly suppressed and the terminal cell markers abnormally expressed in DM mice IECs (P < 0.05). Inhibition or induction on the abundance of TLE1 in IEC-6 cell line resulted in the corresponding dysregulation of Hes1 and intestinal epithelium differentiation (P < 0.05). Demethylation of TLE1 promoter region activates the self-expression in diabetic mice IECs. Subsequently, TLE1, through the transcriptional suppression on expression of Hes1, contributes to the aberrant differentiation of IECs in DM mice.

Expression of Estrogen Receptor Coactivator Proline-, Glutamic Acid- and Leucine-Rich Protein 1 within Paraspinal Muscles in Adolescents with Idiopathic Scoliosis.

PURPOSE: The aim of this study was to detect and assess the estrogen receptor (ESR) coactivator PELP1 expression within human paraspinal skeletal muscles in patients suffering from idiopathic scoliosis. METHODS: During surgical correction of scoliosis the muscle biopsies harvested in 29 females. Presence of PELP1, ESR1 and ESR2 genes transcripts was studied using RT-qPCR technique while immunohistochemistry and western blot methods were used to detect the PEPL1 protein presence. RESULTS: PELP1 expression in deep paraspinal muscles revealed higher than in superficial back muscles (p = 0.005). Positive immunohistochemical staining for PELP1 was observed in the nuclei of the paraspinal muscle cells. Western blot revealed PELP1 protein in all samples. No significant difference in PELP1 expression between the convex and the concave scoliosis side (p>0.05) was found. In deep paraspinal back muscles, a significant correlation between the PELP1 expression level on the concave side and the Cobb angle (r = 0.4; p<0.05) was noted as well as between the PELP1 and ESR1 expression level (r = 0.7; p<0.05) while no correlation between PELP1 and ESR2 expression level was found. CONCLUSION: To our knowledge, three techniques for the first time demonstrated the presence of the PELP1 in paraspinal muscles of patients with idiopathic scoliosis. The PELP1 potential regulatory impact on back muscle function is to be further investigated.

Long Noncoding RNA FosDT Promotes Ischemic Brain Injury by Interacting with REST-Associated Chromatin-Modifying Proteins.

Ischemia induces extensive temporal changes in cerebral transcriptome that influences the neurologic outcome after stroke. In addition to protein-coding RNAs, many classes of noncoding RNAs, including long noncoding RNAs (LncRNAs), also undergo changes in the poststroke brain. We currently evaluated the functional significance of an LncRNA called Fos downstream transcript (FosDT) that is cogenic with Fos gene. Following transient middle cerebral artery occlusion (MCAO) in adult rats, expression of FosDT and Fos was induced. FosDT knockdown significantly ameliorated the postischemic motor deficits and reduced the infarct volume. Focal ischemia also increased FosDT binding to chromatin-modifying proteins (CMPs) Sin3a and coREST (corepressors of the transcription factor REST). Furthermore, FosDT knockdown derepressed REST-downstream genes GRIA2, NFκB2, and GRIN1 in the postischemic brain. Thus, FosDT induction and its interactions with REST-associated CMPs, and the resulting regulation of REST-downstream genes might modulate ischemic brain damage. LncRNAs, such as FosDT, can be therapeutically targeted to minimize poststroke brain damage. SIGNIFICANCE STATEMENT: Mammalian brain is abundantly enriched with long noncoding RNAs (LncRNAs). Functional roles of LncRNAs in normal and pathological states are not yet understood. This study identified that LncRNA FosDT induced after transient focal ischemia modulates poststroke behavioral deficits and brain damage. These effects of FosDT in part are due to its interactions with chromatin-modifying proteins Sin3a and coREST (corepressors of the transcription factor REST) and subsequent derepression of REST-downstream genes GRIA2, NFκB2, and GRIN1. Therefore, LncRNA-mediated epigenetic remodeling could determine stroke outcome.

Prognostic significance of proline, glutamic acid, leucine rich protein 1 (PELP1) in triple-negative breast cancer: a retrospective study on 129 cases.

BACKGROUND: Triple-negative breast cancer (TNBC) is associated with an aggressive clinical course due to the lack of therapeutic targets. Therefore, identifying reliable prognostic biomarkers and novel therapeutic targets for patients with TNBC is required. Proline, glutamic acid, leucine rich protein 1 (PELP1) is a novel steroidal receptor co-regulator, functioning as an oncogene and its expression is maintained in estrogen receptor (ER) negative breast cancers. PELP1 has been proposed as a prognostic biomarker in hormone-related cancers, including luminal-type breast cancers, but its significance in TNBC has not been studied. METHODS: PELP1 immunoreactivity was evaluated using immunohistochemistry in 129 patients with TNBC. Results were correlated with clinicopathological variables including patient's age, tumor size, lymph node stage, tumor grade, clinical stage, histological type, Ki-67 LI, as well as clinical outcome of the patients, including disease-free survival (DFS) and overall survival (OS). RESULTS: PELP1 was localized predominantly in the nuclei of carcinoma cells in TNBC. With the exception of a positive correlation between PELP1 protein expression and lymph node stage (p = 0.027), no significant associations between PELP1 protein expression and other clinicopathological variables, including DFS and OS, were found. However, when PELP1 and Ki-67 LI were grouped together, we found that patients in the PELP1/Ki-67 double high group (n = 48) demonstrated significantly reduced DFS (p = 0.005, log rank test) and OS (p = 0.002, log rank test) than others (n = 81). Multivariable analysis supported PELP1/Ki-67 double high expression as an independent prognostic factor in patients with TNBC, with an adjusted hazard ratio of 2.020 for recurrence (95 % CL, 1.022-3.990; p = 0.043) and of 2.380 for death (95 % CL, 1.138-4.978; p = 0.021). CONCLUSIONS: We found that evaluating both PELP1 and Ki-67 expression in TNBC could enhance the prognostic sensitivity of the two biomarkers. Therefore, we propose that PELP1/Ki-67 double high expression in tumors is an independent prognostic factor for predicting a poor outcome for patients with TNBC.

Significantly increased PELP1 protein expression in primary and metastatic triple-negative breast carcinoma: comparison with GATA3 expression and PELP1's potential role in triple-negative breast carcinoma.

PELP1 is a novel coregulator of nuclear hormone receptors and is implicated in playing a role in driving breast cancer and enhancing metastatic potential. The PELP1 protein expression and potential role of PELP1 in triple-negative breast carcinoma (TNBC) have not been well characterized. We investigated PELP1 expression by immunohistochemistry in primary and metastatic triple-negative tumors in human tissues and compared its expression with GATA-binding protein 3 (GATA3), a novel diagnostic marker for TNBC. We examined the expression of PELP1 and GATA3 in 70 primary TNBC cases and found that PELP1 had a significantly higher frequency of expression compared to GATA3 (96% versus 46%; P < .0001). The mean extent score of expression of PELP1 was also significantly higher than GATA3's expression (3.87 ± 0.07 versus 0.91 ± 0.15; P < .0001). PELP1 had stronger staining intensity than GATA3. Furthermore, PELP1 immunoreactivity was consistently maintained in paired primary and metastatic TNBC cases (100%). The frequency of PELP1 expression (100%) in metastatic triple-negative tumors was higher than that of GATA3 (40%) in the same tumors (P < .0001). These findings indicate that PELP1 is a much more sensitive marker than GATA3 for TNBCs. PELP1 may have diagnostic utility for metastatic TNBC in appropriate settings, such as history of primary TNBC in cases where the primary is negative for GATA3, mammaglobin, and GCDFP-15. The diffuse and strong nuclear immunoreactivity of PELP1 in most cases suggests that PELP1 may be a molecular target for the treatment of TNBC. We hope that this study will provide insights into the role of PELP1 in TNBC.

Increased expression of proline-, glutamic acid- and leucine-rich protein PELP1 in non-small cell lung cancer.

It has been demonstrated that estrogens are able to enhance lung tumorigenesis by estrogen receptor (ER) pathway. ER signaling is a highly complex process that requires a number of different coactivators, including proline-, glutamic acid- and leucine-rich protein-1 (PELP1). We studied PELP1 transcript and protein levels in cancerous and histopathologically unchanged lung tissues obtained from 73 patients diagnosed with non-small cell lung cancer (NSCLC). We observed increased levels of PELP1 transcript (P=0.00001) and protein (P=0.00001) in tumor tissues compared to adjacent histopathologically unchanged tissues. Significant increase of PELP1 transcript/protein level was found in all patients, regardless of gender (males: P=0.0003/P=0.000003; females: P=0.0005/P=0.02), age (≤ 60 patients: P=0.042/P=0.016; >60 patients: P=0.00001/P=0.00001) or histopathological type of tumor (adenocarcinoma [ADC]: P=0.004/P=0.0006; squamous cell carcinoma [SSC]: P=0.0009/P=0.0008). Increased PELP1 transcript/protein levels were also correlated with some lung cancer stage (1a: P=0.07/P=0.02; 1b: P=0.001/P=0.03; 2a: P=0.012/P=0.001), tumor size (T2a: P=0.0006/P=0.001) and lymph node metastasis (N0: P=0.0003/P=0.0006; N1: P=0.017/P=0.003). Moreover, significant increase in PELP1 transcript level in cancer stage 1a (P=0.02) was observed. PELP1 protein content was higher in tumor tissues of patients with cancer stage 3a (P=0.04) and in T1a tumor size (P=0.03). Our studies demonstrate significantly higher amounts of PELP1 transcript and protein in tumor tissues in patients with NSCLC. Moreover, we also determined the association of PELP1 transcript and protein level with some clinicopathological features of NSCLC.

PELP1 overexpression in the mouse mammary gland results in the development of hyperplasia and carcinoma.

Estrogen receptor (ER) coregulator overexpression promotes carcinogenesis and/or progression of endocrine related-cancers in which steroid hormones are powerful mitogenic agents. Recent studies in our laboratory, as well as others, demonstrated that the estrogen receptor coregulator PELP1 is a proto-oncogene. PELP1 interactions with histone demethylase KDM1 play a critical role in its oncogenic functions and PELP1 is a prognostic indicator of decreased survival in patients with breast cancer. However, the in vivo significance of PELP1 deregulation during initiation and progression of breast cancer remains unknown. We generated an inducible, mammary gland-specific PELP1-expressing transgenic (Tg) mouse (MMTVrtTA-TetOPELP1). We found more proliferation, extensive side branching, and precocious differentiation in PELP1-overexpressing mammary glands than in control glands. Aged MMTVrtTA-TetOPELP1 Tg mice had hyperplasia and preneoplastic changes as early as 12 weeks, and ER-positive mammary tumors occurred at a latency of 14 to 16 months. Mechanistic studies revealed that PELP1 deregulation altered expression of a number of known ER target genes involved in cellular proliferation (cyclin D1, CDKs) and morphogenesis (EGFR, MMPs) and such changes facilitated altered mammary gland morphogenesis and tumor progression. Furthermore, PELP1 was hyper-phosphorylated at its CDK phosphorylation site, suggesting an autocrine loop involving the CDK-cyclin D1-PELP1 axis in promoting mammary tumorigenesis. Treatment of PELP1 Tg mice with a KDM1 inhibitor significantly reduced PELP1-driven hyperbranching, reversed alterations in cyclin D1 expression levels, and reduced CDK-driven PELP1 phosphorylation. These results further support the hypothesis that PELP1 deregulation has the potential to promote breast tumorigenesis in vivo and represent a novel model for future investigation into molecular mechanisms of PELP1-mediated tumorigenesis.