Tumor dormancy: Elevated expression of stanniocalcins in late relapsing breast cancer

Protein kinase D drives the secretion of invasion mediators in triple-negative breast cancer cell lines

The protein kinase D (PKD) family members regulate the fission of cargo vesicles at the Golgi complex and play a pro-oncogenic role in triple-negative breast cancer (TNBC). Whether PKD facilitates the secretion of tumor-promoting factors in TNBC, however, is still unknown. Using the pharmacological inhibition of PKD activity and siRNA-mediated depletion of PKD2 and PKD3, we identified the PKD-dependent secretome of the TNBC cell lines MDA-MB-231 and MDA-MB-468. Mass spectrometry-based proteomics and antibody-based assays revealed a significant downregulation of extracellular matrix related proteins and pro-invasive factors such as LIF, MMP-1, MMP-13, IL-11, M-CSF and GM-CSF in PKD-perturbed cells. Notably, secretion of these proteins in MDA-MB-231 cells was predominantly controlled by PKD2 and enhanced spheroid invasion. Consistently, PKD-dependent secretion of pro-invasive factors was more pronounced in metastatic TNBC cell lines. Our study thus uncovers a novel role of PKD2 in releasing a pro-invasive secretome.

MicroRNA‑606 inhibits the growth and metastasis of triple‑negative breast cancer by targeting Stanniocalcin 1

Triple‑negative breast cancer (TNBC) is associated with a poor prognosis; however, treatments for TNBC are limited, with poor outcomes. MicroRNAs (miRNAs/miRs) are small non‑coding RNA molecules that are able to regulate gene expression. The present study aimed to identify differentially expressed miRNAs in patients with breast cancer, and to investigate the functional role of the identified miRNA targets and their effects in vitro and in vivo. Transfection with miR‑606 suppressed TNBC cell proliferation, migration, invasion and tumor sphere‑forming ability, as determined using trypan blue, Transwell and sphere formation assays. Moreover, miR‑606 induced the apoptosis of TNBC cells, as determined by flow cytometric analysis. Furthermore, intratumoral injections of miR‑606 mimics suppressed tumor growth in MDA‑MB‑231 xenografts. In addition, MDA‑MB‑231 cells transfected with miR‑606 mimics exhibited decreased lung metastatic nodules in a mouse tail vein injection model. Notably, miR‑606 and STC1 expression had opposing effects on the overall survival of patients with TNBC. The results of the present study suggested a novel tumor suppressor function for miR‑606 in TNBC, thus indicating its potential application in the development of anticancer miRNA therapeutics.

Quantities of CD3+, CD8+ and CD56+ lymphocytes decline in breast cancer recurrences while CD4+ remain similar

BACKGROUND

Much is known about tumor infiltrating lymphocytes (Tils) in primary breast cancer, as this has been the focus of much research in recent years, but regarding recurrent breast cancer, only few studies have been done. Our aim was to compare the quantities of Tils in primary breast carcinomas and their corresponding recurrences and to analyze the differences in the tumor Tils compositions in correlations with recurrence-free times and the clinicopathology of the tumor.

METHODS

One hundred thirty-seven breast cancer patients self-paired for primary- tumor-recurrence were divided into three groups based on the length of the recurrence-free interval. H&E-staining and immunohistochemical staining with antiCD3, antiCD4, antiCD8 and antiCD56 were performed. Differences in Tils between primaries and recurrences, between the recurrence-free interval groups, and between different clinicopathologic parameters were statistically analyzed.

RESULTS

Fewer stromal CD3+, CD8+ and CD56+ lymphocytes were found at recurrences compared to the primaries. No significant change in the percentage of CD4+ stromal lymphocytes. ER-negative primaries, PR-negative or HER2-positive tumors had more Tils in some subgroups. Ductal primaries had more Tils than lobular primaries and G3 tumors had more Tils than lower-grade tumors. The corresponding differences at recurrences could either not be detected or they were reversed. The fastest recurring group had generally more Tils than the slower groups.

CONCLUSIONS

CD4+ cell numbers did not decline from primary to recurrence in contrast to all other subclasses of lymphocytes. The proportion of CD4+ cells was higher in recurrences than in primaries. Tumors with a higher grade and proliferation rate had higher percentages of Tils. HER2+ and hormone receptor negative tumors tended to have higher Tils scores. In recurrences these differences were not seen or they were reversed.

Development and validation of novel risk prediction models of breast cancer based on stanniocalcin‐1 level

PURPOSE

The function of stanniocalcin-1 (STC-1) in the oncogenesis and progression of tumors has been extensively studied. The purpose of this study was to investigate the relationship between secreted STC-1 and prognosis in patients with breast cancer (BC) and to determine whether STC-1 could be a key prognostic factor in BC.

METHODS

The STC-1 level was measured by ELISA and clinical data from 1210 female patients with BC were used to develop and validate nomograms. We then verified the models through the plotting of ROC curves and calibration curves, calculating the C-index, and performing decision curve analyses (DCA).

RESULTS

The level of STC-1 in the peripheral plasma was significantly correlated with the T stage, N stage, clinical stage, grade, hormone receptors, HER-2 status, and tumor subtype. Cox regression analyses revealed that estrogen receptor(ER) status, N stage, and STC-1 level were risk factors for overall survival (OS), whereas T stage, N stage, and STC-1 level were independent prognostic factors for distant disease-free survival (DDFS) and disease-free survival (DFS). Both the ROC curve and the C-index confirmed the high resolution of these models, while the DCA identified the feasibility of their practical application. In addition, the calibration curves indicated good consistency between the predicted and actual survival rates.

CONCLUSION

Nomograms were created based on STC-1 levels for 3-, 5-, and 7-year OS, DDFS, and DFS of patients with BC respectively. As a key prognostic factor for BC, peripheral blood STC-1 level can be used clinically as a liquid biopsy indicator.

Stanniocalcin 2 (STC2): a universal tumour biomarker and a potential therapeutical target

Stanniocalcin 2 (STC2) is a glycoprotein which is expressed in a broad spectrum of tumour cells and tumour tissues derived from human breast, colorectum, stomach, esophagus, prostate, kidney, liver, bone, ovary, lung and so forth. The expression of STC2 is regulated at both transcriptional and post-transcriptional levels; particularly, STC2 is significantly stimulated under various stress conditions like ER stress, hypoxia and nutrient deprivation. Biologically, STC2 facilitates cells dealing with stress conditions and prevents apoptosis. Importantly, STC2 also promotes the development of acquired resistance to chemo- and radio- therapies. In addition, multiple groups have reported that STC2 overexpression promotes cell proliferation, migration and immune response. Therefore, the overexpression of STC2 is positively correlated with tumour growth, invasion, metastasis and patients' prognosis, highlighting its potential as a biomarker and a therapeutic target. This review focuses on discussing the regulation, biological functions and clinical importance of STC2 in human cancers. Future perspectives in this field will also be discussed.

The Oncogenic and Diagnostic Potential of Stanniocalcin 2 in Hepatocellular Carcinoma

Purpose

Early detection and prognostic prediction of hepatocellular carcinoma (HCC) remain a great challenge. In this study, we explored the role and diagnostic significance of stanniocalcin 2 (STC2), recently identified as a secretory protein, in HCC.

Methods

STC2 mRNA and protein in HCC tissues were examined by qRT-PCR and immunohistochemistry. The regulatory role of HCC growth by STC2 was evaluated in vitro and in vivo. Serum STC2 levels were determined in HCC patients and compared to those with liver cirrhosis (LC) and normal controls (NC). The difference and significance of STC2 levels between groups were analyzed by Mann–Whitney U-test. The diagnostic value of serum STC2 in detecting early HCC was assayed with receiver operating characteristics (ROC). The association of STC2 with overall survival (OS) was determined with Kaplan–Meier method.

Results

STC2 was elevated in about 77.1% HCC patients and correlated with advanced tumor progression. Overexpression or knockdown of STC2 stimulated or suppressed HCC colony formation and xenograft tumor growth. AKT activation played a critical role in tumor-promoting effect of STC2. The median level of serum STC2 in HCC patients (n = 98, 2086.6 ng/L) was 2.6-fold and 4.2-fold that in LC patients (n = 42, 801.9 ng/L) and NC (n = 26, 496.9 ng/L), respectively. A cut-off value 1493 ng/L for STC2 could distinguish early HCC from LC with a sensitivity of 76.9% and a specificity of 76.2%, both of which were superior to AFP at 20 μg/L (sensitivity 69.2%, specificity 52.4%). STC2 was positive in 77.8% (14/18) AFP-negative patients. High STC2 level was correlated with poor overall and disease specific survival.

Conclusion

STC2 is upregulated in both tumor and serum of HCC patients, and its overexpression promotes HCC via AKT pathway. STC2 possesses a diagnostic significance and may serve as an auxiliary biomarker of AFP for detecting early HCC.

Prognostic value of STC1 in solid tumors: a meta-analysis

Aim: The prognostic value of STC1 has been evaluated in solid tumors. However, the results remain controversial. Materials & methods: Relevant studies published up to 27 February 2021 were identified by a comprehensive search of the PubMed, EMBASE and Web of Science databases. Hazard ratios (HRs) and odds ratios with 95% CIs were applied to explore the association between STC1 and survival outcome and clinical characteristics. Results: Sixteen articles involving 2942 participants were included in this meta-analysis. The pooled analysis showed that high STC1 expression was significantly associated with worse overall survival (HR: 1.91; 95% CI: 1.63-2.24) and disease-free survival/progression-free survival/relapse-free survival (HR: 2.01; 95% CI: 1.34-3.02). Conclusion: STC1 may be an effective prognostic marker in solid tumors.

Low Expression of Stanniocalcin 1 (STC-1) Protein Is Associated With Poor Clinicopathologic Features of Endometrial Cancer

Stanniocalcin-1 (STC-1) is a glycoprotein hormone involved in diverse biological processes, including regulation of calcium phosphate homeostasis, cell proliferation, apoptosis, inflammation, oxidative stress responses, and cancer development. The role of STC-1 in endometrial cancer (EC) is yet to be elucidated. In this study, we investigated the protein expression pattern of STC-1 in a tissue microarray (TMA) cohort of hysterectomy specimens from 832 patients with EC. We then evaluated the prognostic value of STC-1 expression regarding the clinicopathologic features and patients survival over a period of 140 months. Our results revealed that in EC tissue samples, STC-1 is mainly localized in the endometrial epithelium, although some expression was also observed in the stroma. Decreased STC-1 expression was associated with factors relating to a worse prognosis, such as grade 3 endometrioid tumors (p = 0.030), deep myometrial invasion (p = 0.003), lymphovascular space invasion (p = 0.050), and large tumor size (p = 0.001). Moreover, STC-1 expression was decreased in tumors obtained from obese women (p = 0.014) and in women with diabetes mellitus type 2 (DMT2; p = 0.001). Interestingly, the data also showed an association between DNA mismatch repair (MMR) deficiency and weak STC-1 expression, specifically in the endometrial epithelium (p = 0.048). No association was observed between STC-1 expression and disease-specific survival. As STC-1 expression was particularly low in cases with obesity and DMT2 in the TMA cohort, we also evaluated the correlation between metformin use and STC-1 expression in an additional EC cohort that only included women with DMT2 (n = 111). The analysis showed no difference in STC-1 expression in either the epithelium or the stroma in women undergoing metformin therapy compared to metformin non-users. Overall, our data may suggest a favorable role for STC-1 in EC behavior; however, further studies are required to elucidate the detailed mechanism and possible applications to cancer treatment.

Serum Follistatin Is Increased in Thyroid Cancer and Is Associated With Adverse Tumor Characteristics in Humans

CONTEXT

Obesity and classical growth factors are associated with thyroid cancer (TC). However, less is known regarding novel hormones such as follistatins and activins. We hypothesized that serum follistatin but not activins would be increased in TC.

OBJECTIVE

This work aimed to assess circulating levels of follistatins, activins, and growth factors in patients with a history of TC vs patients with nonmalignant thyroid diseases.

METHODS

A hospital-based, unmatched case-control study was conducted with 170 thyroidectomized patients due to well-differentiated TC and 106 thyroidectomized patients without history of malignancy. Anthropometric, biochemical, and histological parameters were recorded. Serum samples were collected in the steady state 45 days after surgery. Multivariate models were used to adjust for baseline differences of the unmatched variables. Serum levels of follistatin (FST), follistatin like-3, activin A, activin B, bioactive insulin-like growth factor-1, and stanniocalcin-2 were assayed with novel, highly specific ELISA kits.

RESULTS

In unmatched univariate models, TC patients had higher FST serum levels compared to cancer-free individuals, independently of histological subtype. In multivariate models adjusting for covariates, individuals in the highest tertile of FST levels were associated with an increased risk for the presence of any type of TC or specific histological subtypes, including papillary, follicular and Hürthle-cell carcinoma, and medullary TC. Higher postoperative FST concentrations were found in patients with vascular invasion and distant metastases and associated with TNM staging at diagnosis.

CONCLUSION

FST serum levels are increased in TC patients and correlate with advanced tumor aggressiveness. Future longitudinal studies are needed to confirm and extend our observations.

＜Editors' Choice＞ Stanniocalcin-1 mRNA expression in soft-tissue tumors

Stanniocalcin-1 (STC1) is a glycoprotein that was originally identified as a calcium-regulating hormone in bony fish, and that has been shown to also critically mediate cell growth, proliferation and differentiation, etc. in humans. Increased STC1 expression levels have been previously detected in different human cancer samples, such as those isolated from lung, breast, ovary, colon, pancreas, and liver tumors; thus, the present study evaluated STC1 expression in various soft-tissue tumors. STC1 mRNA isolated from 16 cell lines and 186 clinical soft-tissue tumor specimens were analyzed via quantitative real-time PCR, and the calculated expression levels were normalized to those exhibited by STC1-expressing MDA-MB-231 cells. The results of these analyses did not reveal any specific histological tumor types that displayed significantly increased STC1 expression; however, they did not indicate that STC1 expression was significantly higher in malignant compared to benign soft-tissue tumors. Furthermore, in adipocytic tumors, STC1 expression in dedifferentiated liposarcomas was found to be highest and lowest in lipoma tissues, respectively, suggesting that adipocytic tumors may express increasely high levels of STC1 mRNA as they become histologically more advanced. STC1 expression correlates with the malignancy grade in soft-tissue tumors.

Expression, function and clinical application of stanniocalcin-1 in cancer

The glycoprotein stanniocalcin-1 functions as a regulatory endocrine hormone that maintains the balance of calcium and phosphorus in bony fish and as a paracrine/autocrine factor involved in many physiological/pathological processes in humans, including carcinogenesis. In this review, we provide an overview of (a) the possible mechanisms through which STC1 affects the malignant properties of cancer, (b) transcriptional and post-transcriptional regulation pathways of STC1 and (c) the potential clinical relevance of STC1 as a cancer biomarker and even a therapeutic target in the future. Exploring the role of STC1 in cancer development may provide a better understanding of the tumorigenesis process in humans and may facilitate finding an effective therapeutic method against cancer.

Organophosphate ester tri-o-cresyl phosphate interacts with estrogen receptor α in MCF-7 breast cancer cells promoting cancer growth

Plastic in the ocean degrades to microplastic, thereby enhancing the leaching of incorporated plasticizers due to the increased particle surface. The uptake of microplastic-derived plasticizers by marine animals and the subsequent entry in the food chain raises concerns for adverse health effects in human beings. Frequently used plasticizers as the organophosphate ester tri-o-cresyl phosphate (TOCP) are known to affect the male reproductive system. However, the overall endocrine potential of TOCP and the underlying molecular mechanisms remain elusive as yet. In this study, we investigated the molecular effects of TOCP on estrogen receptor α (ERα)-transfected HEK-ESR1 cells and the human breast cancer cell line MCF-7. Applying virtual screening and molecular docking, we identified TOCP as potent ligand of ERα in silico. Microscale thermophoresis confirmed the binding in vitro with similar intensity as the natural ligand 17-β-estradiol. To identify the molecular mechanisms of TOCP-mediated effects, we used next-generation sequencing to analyze the gene expression pattern of TOCP-treated MCF-7 cells. RNA-sequencing revealed 22 differently expressed genes associated with ESR1 as upstream regulator: CYP1A1, SLC7A11, RUNX2, DDIT4, STC2, KLHL24, CCNG2, CEACAM5, SLC7A2, MAP1B, SLC7A5, IGF1R, CD55, FOSL2, VEGFA, and HSPA13 were upregulated and PRKCD, CCNE1, CEBPA, SFPQ, TNFAIP2, KRT19 were downregulated. The affected genes promote tumor growth by increasing angiogenesis and nutritional supply, favor invasion and metastasis, and interfere with the cell cycle. Based on the gene expression pattern, we conclude TOCP to mediate endocrine effects on MCF-7 cells by interacting with ERα.

Stanniocalcin-1 protein expression profile and mechanisms in proliferation and cell death pathways in prostate cancer

Prostate cancer (PCa) is one of the most prevalent male tumours. Stanniocalcin-1 (STC1) is a glycoprotein and, although the role of STC1 in human cancer is poorly understood, it is suggested to be involved in the development and progression of different neoplasms. This study investigated the protein expression profile of STC1 in PCa and benign prostatic hyperplasia (BPH) samples and STC1 signalling during cell proliferation and cell death in vitro using cell lines. We found higher levels of STC1 in PCa when compared to BPH tissue and that STC1 inhibited forskolin stimulation of cAMP in PC-3 cells. A monoclonal antibody against STC1 was effective in reducing cell proliferation, in promoting cell cycle arrest, and in increasing apoptosis in the same cells. Since STC1 acts as a regulator of prostatic tissue signalling, we suggest that this protein is a novel candidate biomarker for prostate tumour clinical progression and a potential therapeutic target.

Role of stanniocalcin-1 in breast cancer

Breast cancer is a highly heterogeneous disease consisting of five disease subtypes with distinct histological characteristics, clinical behaviors and prognostic features. Stanniocalcin-1 (STC1) is a secreted glycoprotein hormone that has been demonstrated to regulate calcium and phosphate homeostasis. Mammalian STC1 is expressed in various tissues and is implicated in multiple physiological and pathophysiological processes. In addition, growing evidence has suggested that STC1 serves an oncogenic role in a number of different types of tumor. However, the role of STC1 in breast cancer is complex, considering that some studies have shown that it exerts an oncogenic role, whereas other studies have demonstrated the opposite. The aim of the present review article is to evaluate the currently available data on mammalian STC1 and discuss its potential roles in each subtype of breast cancer.

Stanniocalcin 2 (STC2) expression promotes post-radiation survival, migration and invasion of nasopharyngeal carcinoma cells

Background: Stanniocalcin 2 (STC2) expression is upregulated under multiple stress conditions including hypoxia, nutrient starvation and radiation. Overexpression of STC2 correlates with tumor progression and poor prognosis.

Purpose: We previously demonstrated that overexpression of STC2 in nasopharyngeal carcinomas (NPC) positively correlates with radiation resistance and tumor metastasis, two major clinical obstacles to the improvement of NPC management. However, it remains elusive whether STC2 expression is a critical contributing factor for post-radiation survival and metastasis of NPC cells.

Materials and methods: Using the radiation resistant CNE2 cell line as a model, we examined the importance of STC2 expression for post-radiation survival, migration and invasion. Here, we report the establishment of STC2 knockout lines (CNE2-STC2-KO) using the CRISPR/Cas9-based genome editing technique.

Results: Compared with the parental line, STC2-KO cells showed similar proliferation and morphology in normal culture conditions, and loss of STC2 did not compromise the cell tumorigenicity in nude mice model. However, STC2-KO lines demonstrated increased sensitivity to X-radiation under either normoxic or hypoxic conditions. Particularly, upon X-radiation, parental CNE2 cells only slightly whereas STC2-KO cells remarkably decreased the migration and invasion ability. Cell cycle analysis revealed that loss of STC2 accumulated cells in G₁ and G₂/M phases but decreased S-population.

Conclusion: These data indicate that the expression of STC2, which can be stimulated by metabolic or therapeutic stresses, is one important factor to promote survival and metastasis of post-radiation NPC cells. Therefore, targeting STC2 or relative downstream pathways may provide novel strategies to overcome radiation resistance and metastasis of NPC.

Stanniocalcin 2 expression is associated with a favourable outcome in male breast cancer

Breast cancer can occur in either gender; however, it is rare in men, accounting for <1% of diagnosed cases. In a previous transcriptomic screen of male breast cancer (MBC) and female breast cancer (FBC) occurrences, we observed that Stanniocalcin 2 (STC2) was overexpressed in the former. The aim of this study was to confirm the expression of STC2 in MBC and to investigate whether this had an impact on patient prognosis. Following an earlier transcriptomic screen, STC2 gene expression was confirmed by RT‐qPCR in matched MBC and FBC samples as well as in tumour‐associated fibroblasts derived from each gender. Subsequently, STC2 protein expression was examined immunohistochemically in tissue microarrays containing 477 MBC cases. Cumulative survival probabilities were calculated using the Kaplan–Meier method and multivariate survival analysis was performed using the Cox hazard model. Gender‐specific STC2 gene expression showed a 5.6‐fold upregulation of STC2 transcripts in MBC, also supported by data deposited in Oncomine™. STC2 protein expression was a positive prognostic factor for disease‐free survival (DFS; Log‐rank; total p = 0.035, HR = 0.49; tumour cells p = 0.017, HR = 0.44; stroma p = 0.030, HR = 0.48) but had no significant impact on overall survival (Log‐rank; total p = 0.23, HR = 0.71; tumour cells p = 0.069, HR = 0.59; stroma p = 0.650, HR = 0.87). Importantly, multivariate analysis adjusted for patient age at diagnosis, node staging, tumour size, ER, and PR status revealed that total STC2 expression as well as expression in tumour cells was an independent prognostic factor for DFS (Cox regression; p = 0.018, HR = 0.983; p = 0.015, HR = 0.984, respectively). In conclusion, STC2 expression is abundant in MBC where it is an independent prognostic factor for DFS.

IGFBP-4 and PAPP-A in normal physiology and disease

Insulin-like growth factor (IGF) binding protein-4 (IGFBP-4) is a modulator of the IGF system, exerting both inhibitory and stimulatory effects on IGF-induced cellular growth. IGFBP-4 is the principal substrate for the enzyme pregnancy-associated plasma protein-A (PAPP-A). Through IGF-dependent cleavage of IGFBP-4 in the vicinity of the IGF receptor, PAPP-A is able to increase IGF bioavailability and stimulate IGF-mediated growth. Recently, the stanniocalcins (STCs) were identified as novel inhibitors of PAPP-A proteolytic activity, hereby adding additional members to the seemingly endless list of proteins belonging to the IGF family. Our understanding of these proteins has advanced throughout recent years, and there is evidence to suggest that the role of IGFBP-4 and PAPP-A in defining the relationship between total IGF and IGF bioactivity can be linked to a number of pathological conditions. This review provides an overview of the experimental and clinical findings on the IGFBP-4/PAPP-A/STC axis as a regulator of IGF activity and examines the conundrum surrounding extrapolation of circulating concentrations to tissue action of these proteins. The primary focus will be on the biological significance of IGFBP-4 and PAPP-A in normal physiology and in pathophysiology with emphasis on metabolic disorders, cardiovascular diseases, and cancer. Finally, the review assesses current new trajectories of IGFBP-4 and PAPP-A research.

PAPP-A and cancer

The zinc metalloproteinase, PAPP-A, enhances local insulin-like growth factor (IGF) action through cleavage of inhibitory IGF-binding proteins, thereby increasing IGF available for IGF receptor-mediated cell proliferation, migration and survival. In many tumors, enhanced IGF receptor signaling is associated with tumor growth, invasion and metastasis. We will first discuss PAPP-A structure and function, and post-translational inhibitors of PAPP-A expression or proteolytic activity. We will then review the evidence supporting an important role for PAPP-A in many cancers, including breast, ovarian and lung cancer, and Ewing sarcoma.

Prognostic relevance and performance characteristics of serum IGFBP-2 and PAPP-A in women with breast cancer: a long-term Danish cohort study

Measurement of circulating insulin‐like growth factors (IGFs), in particular IGF‐binding protein (IGFBP)‐2, at the time of diagnosis, is independently prognostic in many cancers, but its clinical performance against other routinely determined prognosticators has not been examined. We measured IGF‐I, IGF‐II, pro‐IGF‐II, IGF bioactivity, IGFBP‐2, ‐3, and pregnancy‐associated plasma protein A (PAPP‐A), an IGFBP regulator, in baseline samples of 301 women with breast cancer treated on four protocols (Odense, Denmark: 1993–1998). We evaluated performance characteristics (expressed as area under the curve, AUC) using Cox regression models to derive hazard ratios (HR) with 95% confidence intervals (CIs) for 10‐year recurrence‐free survival (RFS) and overall survival (OS), and compared those against the clinically used Nottingham Prognostic Index (NPI). We measured the same biomarkers in 531 noncancer individuals to assess multidimensional relationships (MDR), and evaluated additional prognostic models using survival artificial neural network (SANN) and survival support vector machines (SSVM), as these enhance capture of MDRs. For RFS, increasing concentrations of circulating IGFBP‐2 and PAPP‐A were independently prognostic [HR_{biomarker doubling}: 1.474 (95% CIs: 1.160, 1.875, P = 0.002) and 1.952 (95% CIs: 1.364, 2.792, P < 0.001), respectively]. The AUC_RFS for NPI was 0.626 (Cox model), improving to 0.694 (P = 0.012) with the addition of IGFBP‐2 plus PAPP‐A. Derived AUC_RFS using SANN and SSVM did not perform superiorly. Similar patterns were observed for OS. These findings illustrate an important principle in biomarker qualification—measured circulating biomarkers may demonstrate independent prognostication, but this does not necessarily translate into substantial improvement in clinical performance.

Stanniocalcin Expression as a Predictor of Late Breast Cancer Recurrence

Background: Expression of human paracrine hormones stanniocalcin 1 (STC1) and stanniocalcin 2 (STC2) may potentiate late breast cancer recurrence. We tested the hypothesis that expression of STC1 and STC2 in primary breast tumors is more strongly associated with late versus early recurrences.Methods: A total of 541 estrogen receptor-positive, tamoxifen-treated (ER⁺/TAM⁺) and 300 ER-negative, tamoxifen-untreated (ER^-/TAM^-) breast cancer patients who experienced recurrence within 10 years of primary diagnosis and matched recurrence-free controls were selected from a cohort of 11,251 Danish breast cancer patients diagnosed with stage I, II, or III breast cancer during 1985 to 2001. The association between IHC expression of STC1 and STC2 in primary breast tumor tissue microarrays and breast cancer recurrence was evaluated within median time to recurrence quintiles.Results: The association between STC1 expression, dichotomized as positive or negative, and recurrence was strongly positive for the final time quintile (6-10 years postdiagnosis) in the ER⁺/TAM⁺ group [aOR = 2.70; 95% confidence interval (CI): 1.22-5.98]. Regression of the log ORs relating dichotomous STC1 and STC2 expression to recurrence by median time to recurrence (year) resulted in a relatively large positive effect estimate for STC1 (β = 0.16; 95% CI, -0.03-0.36) and a near-null positive effect estimate for STC2 (β = 0.04; 95% CI, -0.14-0.21).Conclusions: Our results suggest a stronger association between primary tumor STC1 expression and late recurrence, as opposed to early recurrence, although no clear trend was apparent.Impact: STC1 expression in the primary tumor may potentiate late recurrences, suggesting dormancy pathways that merit further investigation. Cancer Epidemiol Biomarkers Prev; 27(6); 653-9. ©2018 AACR.

Effects of STC1 overexpression on tumorigenicity and metabolism of hepatocellular carcinoma

Stanniocalcin-1 (STC1) is a paracrine factor associated with inflammation and carcinogenesis. Using clinicopathological data, we previously reported that a greater expression of STC1 in hepatocellular carcinoma (HCC) was significantly correlated with smaller tumor size. The underlying mechanism on the correlation is not known. In this study, using a metastatic HCC cell-line (MHCC-97L, P) and lentiviral vector mediated-STC1 overexpression, the inoculation of STC1-overexpressing MHCC-97L (S1) cells in a nude mice xenograft model demonstrated reductions in tumor mass and volume. As compared with P cells, S1 cells exhibited epithelial phenotype with significantly lower plating efficiency and reduced migratory and proliferative potential. Using coulter counter for cell-sizing, S1 cells (17.6 μm) were significantly smaller than P cells (19.6 μm). Western blot analysis revealed that S1 cells exhibited reduced expression level of phosphorylated ribosomal protein S6 (p-rpS6). Moreover, an inhibition of the upstream kinase p70^S6K was evident with the dephosphorylation of Thr389 in the linker domain of the kinase. The inhibition of p70^S6K/p-rpS6 pathway was accompanied with reduced cellular ATP level and increase of p-AMPK in S1 cells. Significantly lower rates of glycolysis and extracellular O₂ consumption in S1 cells exhibited a lower cellular energy status. Since a faster rate of ATP production is essential to support cancer growth and metastasis, the present study identified the effect of STC1-overexpression on reducing energy metabolism, leading to an activation of AMPK pathway but an inhibition of p70^S6K/p-rpS6 signaling to reduce tumor growth.

A Review of the Clinical Implications of Breast Cancer Biology

BACKGROUND

Histologically similar tumors may have different prognoses and responses to treatment. These differences are due to molecular differences. Hence, in this review, the biological interaction of breast cancer in several different areas is discussed. In addition, the performance and clinical application of the most widely-recognized biomarkers, metastasis, and recurrences from a biological perspective and current global advances in these areas are addressed.

OBJECTIVE

This review provides the performance and clinical application of the most widely-recognized biomarkers, metastasis, and recurrences from the biological perspective and current global advances in these areas.

METHODS

PubMed, Scopus, and Google Scholar were searched comprehensively with combinations of the following keywords: "breast cancer," "biological markers," and "clinical." The definition of breast cancer, diagnostic methods, biological markers, and available treatment approaches were extracted from the literature.

RESULTS

Estrogen receptor (ER), progesterone receptor (PR), human epidermal growth factor receptor-2 (HER-2), and Ki-67 are the most well-known biological markers that have important roles in prognosis and response to therapeutic methods. Some studies showed the response of ER-positive and PR-negative tumors to anti-estrogenic treatment to be lower than ER-positive and PR-positive tumors. Patients with high expression of HER-2 and Ki-67 had a poor prognosis. In addition, recent investigations indicated the roles of new biomarkers, such as VEGF, IGF, P53 and P21, which are associated with many factors, such as age, race, and histological features.

CONCLUSION

The objective of scientists, from establishing a relationship between cancer biology infrastructures with clinical manifestations, is to find new ways of prevention and progression inhibition and then possible introduction of less dangerous and better treatments to resolve this dilemma of human society.

A Case Report of Local Recurrence Developing 24 Years After Mastectomy for Breast Cancer Recurrence From Breast Cancer After 24 Years

INTRODUCTION

Breast cancer is a commonly diagnosed cancer, in which most patients' metastases (about 75%) occurred in 5 years after the initial diagnosis, especially in 3 years. Recrudescence exceeding 20 years is rarely reported in the past several decades.Case information: A 68-year-old female patient presented with breast cancer in which 3 focal increased 18F-fluorodeoxyglucose uptake in the right supraclavicular lymph node, the mediastinum and sternum were found on positron emission tomography and computed tomography. Then we learned that the patient had suffered from breast cancer and been given a right-sided mastectomy 24 years ago. Histopathology from the mediastinum revealed metastatic, moderately differentiated breast adenomatous cell carcinoma.

CONCLUSION

We report this late recurrence of breast cancer 24 years following mastectomy, suggesting that possible recurrence of this disease with a 24-year latency period should be taken into consideration.

Stanniocalicin 2 suppresses breast cancer cell migration and invasion via the PKC/claudin-1-mediated signaling

Stanniocalcin (STC), a glycoprotein hormone, is expressed in a wide variety of tissues to regulate Ca²⁺ and PO4^- homeostasis. STC2, a member of STC family, has been reported to be associated with tumor development. In this study, we investigated whether the expression of STC2 is associated with migration and invasion of breast cancer cells. We found that breast cancer cell line 231 HM transfected with STC2 shRNA displayed high motility, fibroblast morphology, and enhanced cell migration and invasion. Introduction of STC2 in 231 cells reduced cell migration and invasion. In response to irradiation, silencing of STC2 in 231 HM cells reduced apoptosis, whereas overexpression of STC2 in 231 cells promoted apoptosis, compared with in control cells. Mechanistic study showed that STC2 negatively regulated PKC to control the expression of Claudin-1, which subsequently induced the expressions of EMT-related factors including ZEB1, ZO-1, Slug, Twist, and MMP9. Suppression of PKC activity by using a PKC inhibitor (Go 6983) restored the normal motility of STC2-silenced cells. Furthermore, in vivo animal assay showed that STC2 inhibited tumorigenesis and metastasis of breast cancer cells. Collectively, these results indicate that STC2 may inhibit EMT at least partially through the PKC/Claudin-1-mediated signaling in human breast cancer cells. Thus, STC2 may be exploited as a biomarker for metastasis and targeted therapy in human breast cancer.

Hypoxia-induced overexpression of stanniocalcin-1 is associated with the metastasis of early stage clear cell renal cell carcinoma

Background

Although metastasis of clear cell renal cell carcinoma (ccRCC) is predominantly observed in late stage tumors, early stage metastasis of ccRCC can also be found with indefinite molecular mechanism, leading to inappropriate clinical decisions and poor prognosis. Stanniocalcin-1 (STC1) is a glycoprotein hormone involved in calcium/phosphate homeostasis, which regulates various cellular processes in normal development and tumorigenesis. This study aimed to investigate the role and mechanism of regulation of STC1 in the metastasis of early stage ccRCC.

Methods

STC1 mRNA and protein expression was determined in ccRCC surgical specimens, RCC cell lines, and human kidney tubule epithelial cell line HKC by real-time polymerase chain reaction (RT-PCR) and western blotting. Immunohistochemistry staining (IHC) and immunofluorescence were also used to examine the expression and localization of STC1 in ccRCC tissues and cancer cells. Knockdown and overexpression studies were conducted in vitro in RCC cell lines using small interfering RNAs (siRNA) and lentiviral-mediated gene delivery to evaluate the role of STC1 in cell proliferation, anchorage-dependent and independent growth, cell cycle control, and migration and invasion.

Results

STC1 mRNA and protein expression were significantly up-regulated in tumors when compared with non-tumor tissues, with the greatest increase in expression observed in metastatic tissues. Clinicopathological analysis revealed that STC1 mRNA expression was associated with Fuhrman tumor grade (P = 0.008) and overall Tumor Node Metastasis (TNM) staging (P = 0.018). STC1 expression was elevated in T1 stage metastatic tumors when compared with localized tumors, and was positively correlated with average tumor diameter. Silencing of STC1 expression by Caki-1 and A498 resulted in the inhibition of cell proliferation, migration, and invasion, meanwhile down-regulation of STC1 impaired epithelial–mesenchymal transition (EMT) of ccRCC cell lines. Overexpression of STC1 in Caki-2 enhanced cell growth and proliferation but not migration and invasion. Further investigation identified hypoxia and HIF-1α as candidate regulators of STC1 expression.

Conclusions

Our findings demonstrate a role for STC1 in metastasis of early stage ccRCC and suggest that STC1 may be a biomarker of potential value both for the prognosis of this disease and for guiding clinical decisions regarding surgical strategies and adjuvant treatment.

Electronic supplementary material

The online version of this article (doi:10.1186/s12967-015-0421-4) contains supplementary material, which is available to authorized users.

The role of PAPP-A in the IGF system: location, location, location

Although discovered as a placental protein present abundantly in the circulation of pregnant women, pregnancy-associated plasma protein-A (PAPP-A) is widely expressed in multiple tissues. PAPP-A is a highly specific metalloproteinase binding tightly to glycosaminoglycans present on the surface of cells. By cleaving a subset of insulin-like growth factor binding proteins (IGFBPs), PAPP-A thus functions within tissues as a growth-promoting enzyme, releasing bioactive IGF in close proximity to the IGF receptor. IGFBP-4 is believed to be the principal PAPP-A substrate, and the focus in this review is on PAPP-A enzymatic activity and its role in the PAPP-A-IGFBP-4-IGF axis, which is subject to regulation at several different levels. These include e.g., transcriptional control, competing reactions potentially sequestering IGF from IGFBP-4 and hence antagonizing PAPP-A-mediated IGF activation, and proteolytic inhibition of PAPP-A. The latter may involve the protein stanniocalcin-2 (STC2), recently found to potently inhibit PAPP-A activity by forming a covalent complex with PAPP-A. PAPP-A or complex-bound variants may escape from pathological tissues into the circulation. It is emphasized that the potential use of PAPP-A as a diagnostic or predictive biomarker in nonpregnant individuals requires precise knowledge of analyte identity and assay specificity in addition to an appropriate material for standardization. Finally, PAPP-A may serve as a therapeutic target to indirectly inhibit IGF signaling in tissues where this is driven by increased PAPP-A activity. By taking advantage of the intricate interaction between PAPP-A and IGFBP-4, highly specific and selective inhibition of PAPP-A is possible.

Stanniocalcin-2 inhibits mammalian growth by proteolytic inhibition of the insulin-like growth factor axis

Mammalian stanniocalcin-2 (STC2) is a secreted polypeptide widely expressed in developing and adult tissues. However, although transgenic expression in mice is known to cause severe dwarfism, and targeted deletion of STC2 causes increased postnatal growth, its precise biological role is still unknown. We found that STC2 potently inhibits the proteolytic activity of the growth-promoting metalloproteinase, pregnancy-associated plasma protein-A (PAPP-A). Proteolytic inhibition requires covalent binding of STC2 to PAPP-A and is mediated by a disulfide bond, which involves Cys-120 of STC2. Binding of STC2 prevents PAPP-A cleavage of insulin-like growth factor-binding protein (IGFBP)-4 and hence release within tissues of bioactive IGF, required for normal growth. Concordantly, we show that STC2 efficiently inhibits PAPP-A-mediated IGF receptor signaling in vitro and that transgenic mice expressing a mutated variant of STC2, STC2(C120A), which is unable to inhibit PAPP-A, grow like wild-type mice. Our work identifies STC2 as a novel proteinase inhibitor and a previously unrecognized extracellular component of the IGF system.

Luminal breast cancer metastases and tumor arousal from dormancy are promoted by direct actions of estradiol and progesterone on the malignant cells

Introduction

Luminal, estrogen receptor-positive (ER⁺) breast cancers can metastasize but lie dormant for years before recurrences prove lethal. Understanding the roles of estrogen (E) or progestin (P) in development of luminal metastases or in arousal from dormancy is hindered by few preclinical models. We have developed such models.

Methods

Immunocompromised, ovariectomized (ovx’d) mice were intracardiac-injected with luminal or basal human breast cancer cells. Four lines were tested: luminal ER⁺PR⁺ cytokeratin 5-negative (CK5⁻) E3 and MCF-7 cells, basal ER⁻PR⁻CK5⁺ estrogen withdrawn-line 8 (EWD8) cells, and basal ER⁻PR⁻CK5⁻ MDA-MB-231 cells. Development of micrometastases or macrometastases was quantified in ovx’d mice and in mice supplemented with E or P or both. Metastatic deposits were analyzed by immunohistochemistry for luminal, basal, and proliferation markers.

Results

ER⁻PR⁻ cells generated macrometastases in multiple organs in the absence or presence of hormones. By contrast, ovx’d mice injected with ER⁺PR⁺ cells appeared to be metastases-free until they were supplemented with E or E+P. Furthermore, unlike parental ER⁺PR⁺CK5⁻ cells, luminal metastases were heterogeneous, containing a significant (6% to 30%) proportion of non-proliferative ER⁻PR⁻CK5⁺ cells that would be chemotherapy-resistant. Additionally, because these cells lack receptors, they would also be endocrine therapy-resistant. With regard to ovx’d control mice injected with ER⁺PR⁺ cells that appeared to be metastases-free, systematic pathologic analysis of organs showed that some harbor a reservoir of dormant micrometastases that are ER⁺ but PR⁻. Such cells may also be endocrine therapy- and chemotherapy-resistant. Their emergence as macrometastases can be triggered by E or E+P restoration.

Conclusions

We conclude that hormones promote development of multi-organ macrometastases in luminal disease. The metastases display a disturbing heterogeneity, containing newly emergent ER⁻PR⁻ subpopulations that would be resistant to endocrine therapy and chemotherapy. Similar cells are found in luminal metastases of patients. Furthermore, lack of hormones is not protective. While no overt metastases form in ovx’d mice, luminal tumor cells can seed distant organs, where they remain dormant as micrometastases and sheltered from therapies but arousable by hormone repletion. This has implications for breast cancer survivors or women with occult disease who are prescribed hormones for contraception or replacement purposes.

Electronic supplementary material

The online version of this article (doi:10.1186/s13058-014-0489-4) contains supplementary material, which is available to authorized users.

Clinical significance of stanniocalcin expression in tissue and serum of gastric cancer patients

PURPOSE

Stanniocalcin (STC) has been recognized as a potential biomarker in a variety of cancers. The aim of this study was to examine STC1 and STC2 expression in tumor and serum samples from gastric cancer (GC) patients.

METHODS

A total of 83 GC patients treated with radical resection were enrolled in this study. Immunohistochemistry was used to detect STC protein expression in paired tumor and adjacent normal tissues. Serum STC levels were determined by enzyme-linked immunosorbent assay (ELISA). The receiver operating characteristics (ROC) curve was constructed to describe diagnostic specificity and sensitivity.

RESULTS

Both of STC1 and STC2 protein expression were upregulated in GC tissues compared with that in normal ones. Moreover, the high/moderate of STC1 protein was significantly associated with lymph metastasis, clinical stage and adverse 3-year progression-free survival (PFS). In addition, serum STC1 and STC2 expression in GC patients were much higher than that in patients with benign gastric disease, which decreased at postoperative 7-10 days. The sensitivity of serum STC protein also showed superiority over CEA and CA19-9.

CONCLUSIONS

STC upregulation plays an important role in GC development, and serum STC1 and STC2 might function as promising tumor markers for GC diagnosis and prognosis.

Stanniocalcin-2 (STC2): A potential lung cancer biomarker promotes lung cancer metastasis and progression

The homodimeric glycoprotein, stanniocalcin 2 (STC2) is previously known to be involved in the regulation of calcium and phosphate transport in the kidney and also reported to play multiple roles in several cancers. However, its function and clinical significance in lung cancer have never been reported and still remain uncertain. Here, we investigated the possibility of STC2 as a lung cancer biomarker and identified its potential role in lung cancer cell growth, metastasis and progression. Proteomic analysis of secretome of primary cultured lung cancer cells revealed higher expression of STC2 in cancers compared to that of adjacent normal cells. RT-PCR and Western blot analyses showed higher mRNA and protein expressions of STC2 in lung cancer tissues compared to the adjacent normal tissues. Knockdown of STC2 in H460 lung cancer cells slowed down cell growth progression and colony formation. Further analysis revealed suppression of migration, invasion and delayed G0/G1 cell cycle progression in the STC2 knockdown cells. STC2 knockdown also attenuated the H202-induced oxidative stress on H460 cell viability with a subsequent increase in intracellular ROS levels, which suggest a protective role of STC2 in redox regulatory system of lung cancer. These findings suggest that STC2 can be a potential lung cancer biomarker and plays a positive role in lung cancer metastasis and progression. This article is part of a Special Issue entitled: Medical Proteomics.

Stanniocalcin 2 expression predicts poor prognosis of hepatocellular carcinoma

Previous studies have shown that the expression level of stanniocalcin 2 (STC2) is associated with tumor progression. However, to date, the association between STC2 and clinicopathological factors in hepatocellular carcinoma (HCC) has not been investigated. The clinical significance of STC2 was investigated in 30 fresh HCC samples using western blot analysis and in 240 HCC tissues using immunohistochemical analysis. The level of STC2 in cancerous tissue was higher than in the matched non-cancerous tissues. Using immunohistochemistry, the STC2-positive group exhibited a higher incidence of lymph node metastasis and venous invasion compared with the STC2-negative group. Kaplan-Meier survival analysis revealed that the positive expression of STC2 correlated with poor overall survival (OS) and disease-free survival of HCC patients (P<0.01). STC2 expression was observed to be an independent prognostic factor for OS in HCC patients by multivariate analysis (hazard ratio, 2.39; 95% confidence interval, 1.04–5.89; P=0.013). These data suggest that STC2 expression may be a useful indicator of poor prognosis in HCC patients.

Stanniocalcin-1 promotes metastasis in a human breast cancer cell line through activation of PI3K

Stanniocalcin-l (STC-1) is a secreted glycoprotein hormone that regulates calcium and phosphate homeostasis. STC-1 expression is upregulated in several cancers including breast cancer, and has been shown to be prognostic. Although these clinical observations implicate STC-1 as a potential tumor marker, it is still unclear whether STC-1 confers a malignant phenotype. In this study, this question was addressed by overexpressing STC-1 in the human breast cancer cell line MDA-MB-231 and examining the resultant phenotype in vitro and in vivo. Overexpression of STC-1 enhanced invasiveness of MDA-MB-231 cells in vitro and promoted their lung metastasis in vivo, while having no effect on proliferation, adhesion, or proteinase activity. The addition of soluble STC-1 to MDA-MB-231 cultures resulted in the activation of the phosphoinositide 3-kinase (PI3K)/Akt signaling pathway, suggesting a mechanistic basis for the observed increases in cell motility and metastasis. Taken together, it was indicated that secreted STC-1 promotes metastatic potential of breast cancer cells via activation of PI3K/AKT.

Expression of stanniocalcin-1 and stanniocalcin-2 in laryngeal squamous cell carcinoma and correlations with clinical and pathological parameters

Background

Stanniocalcin-1 (STC1) and stanniocalcin-2 (STC2) are secreted glycoprotein hormones involved in various types of human malignancies. The roles of STC1 and STC2 in laryngeal squamous cell carcinoma (LSCC) remain unknown. We investigated correlations between STC1 and STC2 expression and clinicopathological or prognostic factors in LSCC.

Methods

Pre-surgical peripheral blood samples were collected between 2012 and 2013 from 62 patients with LSCC. Quantitative RT-PCR analysis was performed to examine mRNA levels of STC1 and STC2. Immunohistochemistry was performed to retrospectively analyze 90 paraffin-embedded LSCC tissue samples, which were obtained from patients who received surgery between 2006 and 2009. These patients did not have histories of treatment or malignancies. Univariate analysis of patient survival was performed by the Kaplan–Meier method. Multivariate analyses were performed with the Cox proportional hazards model.

Results

The relative mRNA levels of STC1 and STC2 in peripheral blood were significantly greater in LSCC patients than those of healthy volunteers (both P<0.05). STC2 protein expression in tumor tissues was associated with invasion into the thyroid cartilage, T-Stage, lymphatic metastasis, clinical stage, and pathological differentiation (all P<0.05). In addition, STC2 protein expression was an independent prognostic factor for overall survival in patients with LSCC (P = 0.025). In contrast, STC1 expression only correlated with clinical stage (P = 0.026) and was not an independent or significant prognostic factor.

Conclusions

Circulating STC1 and STC2 mRNA are potentially useful blood markers for LSCC. Our results strongly suggest that the STC2 protein, but not STC1, may be a valuable biomarker for LSCC malignancies and a prognostic marker for poor outcome following surgery. Future studies should examine STC2 as a novel molecular target for the treatment of LSCC.

Survival analyses correlate stanniocalcin 2 overexpression to poor prognosis of nasopharyngeal carcinomas

Background

Stanniocalcin 2 (STC2) is overexpressed in several types of human cancers, and its overexpression positively correlates to tumor progression and poor prognosis. However, the clinical significance of STC2 overexpression in nasopharyngeal carcinomas (NPC) has not been investigated. This study examined STC2 expression in a cohort of 94 NPC samples, and explored its value in clinical diagnosis and prognosis.

Methods

Tumor samples from 94 patients diagnosed in 2008 were studied. All samples were obtained prior to treatment start. All cases were clinically diagnosed and pathologically confirmed to be poorly differentiated or undifferentiated NPC without distant metastasis, and have been treated with radical radiation therapy and followed-up for five years. Survival analyses were performed.

Results

Of the 94 NPC samples, STC2 overexpression (STC2+) was detected in 65 samples (69.1%). Overall survival rate of STC2 (+) patients is significantly lower than that of patients with normal STC2 levels (72.2% vs. 96.4%, respectively, P = 0.049). Moreover, STC2 (+) is also strongly predictive of a low progression-free survival and distant metastasis-free survival (63.0% vs 92.9%. P = 0.007; and 77.0% vs 96.4%. P = 0.028). Of the 54 patients treated with IMRT, residual tumors were found in 54.8% of STC2 positive patients (17/31), but only in 17.4% of STC2 negative ones (4/23), suggesting STC2 overexpression predicts a higher risk of residual tumors after IMRT.

Conclusions

STC2 overexpression correlates to poor prognosis for NPC and may be useful as a novel biomarker to predict NPC responses to radiation. Whether STC2 promotes NPC progression and metastasis remains to be investigated.

Anti-VEGF antibody therapy induces tumor hypoxia and stanniocalcin 2 expression and potentiates growth of human colon cancer xenografts

Tumor angiogenesis plays a critical role in colorectal cancer progression. Recent randomized clinical trials have revealed the additive effect of bevacizumab, a humanized monoclonal antibody against vascular endothelial growth factor (VEGF)-A, to conventional chemotherapy in the improved survival of patients with metastatic colorectal cancer. However, a number of preclinical reports indicate the development of resistance to anti-angiogenic therapy. In this study, we addressed the effects of anti-VEGF antibodies on the growth and malignant behavior of colorectal cancer cells. TK-4, a solid tumor strain derived from a colon cancer patient, was subcutaneously or orthotopically implanted into nude mice. Short-term administration of anti-VEGF antibodies inhibited the growth of cecal tumors at day 14 by suppressing mitosis, but prolonged treatment resulted in the recovery of cellular proliferation and suppression of apoptosis at day 35. Intratumoral hypoxia induced by anti-VEGF antibody treatment resulted in activation of hypoxia inducible factor-1α protein and an increased number of aldehyde dehydrogenase 1-positive tumor cells. In microarray analysis, stanniocalcin 2 (STC2) was the most highly upregulated gene in anti-VEGF antibody-treated tumors. In vitro analyses showed that the growth and migration of SW480 colon cancer cells under hypoxic conditions were significantly inhibited by knockdown of STC2. In vivo serial transplantation of TK-4 revealed that long-term administration of anti-VEGF antibodies increased the tumorigenicity of colon cancers and accelerated tumor growth when transplanted into secondary recipient mice. Our data provide a potential molecular explanation for the limited clinical effectiveness of anti-VEGF antibodies.

Changes in the peripheral blood and bone marrow from untreated advanced breast cancer patients that are associated with the establishment of bone metastases

Bone metastasis is an incurable complication of breast cancer affecting 70-80 % of advanced patients. It is a multistep process that includes tumour cell mobilisation, intravasation, survival in the circulation, extravasation, migration and proliferation in the bone marrow/bone. Although novel findings demonstrate the bone marrow microenvironment significance in bone metastatic progression, a majority of studies have focused on end-stage disease and little is known about how the pre-metastatic niche arises in the bone marrow/bone tissues. We demonstrated a significant increase in patients' peripheral blood plasma ability to induce transendothelial migration of MCF-7 cells compared with healthy volunteers. Moreover, high RANKL, MIF and OPG levels in patients' peripheral blood could play a role in the intravasation, angiogenesis, survival and epithelial-mesenchymal transition of circulating tumour cells. Also, we observed a significant increase in patients' bone marrow plasma capacity to induce transendothelial migration of MDA-MB231 and MCF-7 cells compared with healthy volunteers. Furthermore, patients' bone marrow mesenchymal stem cells could control the recruitment of tumour cells, modifying the MCF-7 and MDA-MB231 cell migration. In addition, we found a significantly higher MDA-MB231 cell proliferation when we used patients' bone marrow plasma compared with healthy volunteers. Interestingly, PDGF-AB, ICAM-1 and VCAM-1 levels in patients' bone marrow were significantly higher than the values of healthy volunteers, suggesting that they could be involved in the cancer cell extravasation, bone resorption and cancer cell proliferation. We believe that these results can reveal new information about what alterations happen in the bone marrow of advanced breast cancer patients before bone colonisation, changes that create optimal soil for the metastatic cascade progression.

The difference in prognostic factors between early recurrence and late recurrence in estrogen receptor-positive breast cancer: nodal stage differently impacts early and late recurrence

Background

Probability of recurrence in patients with estrogen receptor (ER)-positive breast cancer remains constant for long periods. We compared tumor burden impact on late versus early recurrence in our cohort with long-term follow-up.

Methods

Five hundred and ninety five patients diagnosed with ER-positive breast cancer between 1989 and 2001 were classified into three groups: early recurrence within 5 years, late recurrence after 5 years, and no recurrence. We identified prognostic factors among the groups using logistic regression analysis.

Results

At median follow-up of 11.7 years, among 595 ER-positive women, 98 (16.4%) had early recurrence and 58 (9.7%) had late recurrence. On multivariate analysis, higher nodal stage (N0 vs. N2, odds ratio [OR] 3.189; N0 vs. N3, OR 9.948), higher histologic grade (grade 1 vs. grade 2, OR 3.896; grade 1 vs. grade 3, OR 5.945), age >35 years (OR 0.295), and receiving endocrine therapy (OR 0.293) affected early recurrence. Compared to no recurrence, receiving endocrine therapy (OR 0.285) was solely related to decreased risk of late recurrence. Increased risk of early recurrence was noted with the higher nodal stage when early and no recurrences were compared. This phenomenon was not found in late recurrence. In the last comparison between the early and late recurrence, higher nodal stage (N0 vs. N3, OR 16.779) and higher histologic grade (grade 1 vs. grade 3, OR 18.111) repeatedly weighted for early recurrence.

Conclusions

Nodal burden had an attenuated influence on late recurrence, which suggests that, unlike early recurrence, tumor biology might have a more important role than tumor load for late recurrence in ER-positive disease.

ER, PR, HER2, Ki-67 and CK5 in Early and Late Relapsing Breast Cancer-Reduced CK5 Expression in Metastases

Breast cancer can recur even decades after the primary therapy. Markers are needed to predict cancer progression and the risk of late recurrence. The estrogen receptor (ER), progesterone receptor (PR), human epidermal growth factor receptor-2 (HER2), proliferation marker Ki-67, and cytokeratin CK5 were studied to find out whether their expression or occurrence in subgroups of breast cancers correlated with the time of recurrence. The expression of HER2, ER, PR, Ki-67, and CK5 was studied by IHC in 72 primary breast cancers and their corresponding recurrent/metastatic lesions. The patients were divided into three groups according to the time of the recurrence/metastasis: before two years, after 5 years, and after 10 years. Based on their IHC profiles, the tumors were divided into surrogates of the genetically defined subgroups of breast cancers and the subtype definitions were as follows: luminal A (ER or PR+HER2–), luminal B (ER or PR+HER2+), HER2 overexpressing (ER–PR–HER2+), triple-negative (ER–PR–HER2–), basal-like (ER–PR–HER2–CK5+), non-classified (ER–PR–HER2–CK5–) and luminobasal (ER or PR+CK5+). In multivariate analysis, tumor size and HER2 positivity were a significant risk of early cancer relapse. The metastases showed a significantly lower CK5 expression. CK5 positivity distinguished triple negative tumors into rapidly and slowly recurring cancers. The IHC subtype ER or PR+HER2– luminal A presented a significantly lower risk of early tumor recurrence. Ki-67 expression denoted early-relapsing tumors and correlated linearly with tumor progression, since Ki-67 positivity declined gradually from early-relapsing toward late-recurring cancers.

Strategy for SRM-based verification of biomarker candidates discovered by iTRAQ method in limited breast cancer tissue samples

Since LC-MS-based quantitative proteomics has become increasingly applied to a wide range of biological applications over the past decade, numerous studies have performed relative and/or absolute abundance determinations across large sets of proteins. In this study, we discovered prognostic biomarker candidates from limited breast cancer tissue samples using discovery-through-verification strategy combining iTRAQ method followed by selected reaction monitoring/multiple reaction monitoring analysis (SRM/MRM). We identified and quantified 5122 proteins with high confidence in 18 patient tissue samples (pooled high-risk (n=9) or low-risk (n=9)). A total of 2480 proteins (48.4%) of them were annotated as membrane proteins, 16.1% were plasma membrane and 6.6% were extracellular space proteins by Gene Ontology analysis. Forty-nine proteins with >2-fold differences in two groups were chosen for further analysis and verified in 16 individual tissue samples (high-risk (n=9) or low-risk (n=7)) using SRM/MRM. Twenty-three proteins were differentially expressed among two groups of which MFAP4 and GP2 were further confirmed by Western blotting in 17 tissue samples (high-risk (n=9) or low-risk (n=8)) and Immunohistochemistry (IHC) in 24 tissue samples (high-risk (n=12) or low-risk (n=12)). These results indicate that the combination of iTRAQ and SRM/MRM proteomics will be a powerful tool for identification and verification of candidate protein biomarkers.

Stanniocalcin 2, forms a complex with heme oxygenase 1, binds hemin and is a heat shock protein

Stanniocalcin 2 (STC2) is a homolog of stanniocalcin 1, a 56kD glycoprotein hormone that originally was found to confer calcitonin-like activity in fish. Human STC2 is expressed in various tissues such as kidney, spleen, heart, and pancreas. STC2 has been demonstrated to be induced by different kinds of stress and display cytoprotective activity, but the molecular mechanism is poorly understood. Heme oxygenase 1 (HO1) degrades heme to biliverdin, carbon monoxide and free iron, and is a stress-responsive protein. Using yeast two-hybrid screening we identified HO1 as a binding partner of STC2. The interaction was validated by in vivo co-immunoprecipitation and immunofluorescence. The binding site for HO1 was located to amino acids 181-200 of STC2. We also found that STC2 binds hemin via a consensus heme regulatory motif. Moreover, STC2 expression was induced by heat shock in HEK293 cells. Taken together, our findings point to three novel functions of STC2, and suggest that STC2 interacts with HO1 to form a eukaryotic 'stressosome' involved in the degradation of heme.

Evolution and roles of stanniocalcin

In fish, stanniocalcin-1 (STC1) is a key endocrine factor that acts on gill, intestine and kidney to regulate serum calcium and phosphate homeostasis. The recent identification and study of mammalian STCs (STC1 and STC2) revealed that the hormones are made in virtually all tissues and they act primarily as paracrine/autocrine factors to regulate various biological functions. Based on their ubiquitous expression patterns and generally undetectable levels in blood serum, it is unlikely that the mammalian STCs play important roles in serum Ca(2+)/P(i) homeostasis. However current evidences still support the local action of STCs in Ca(2+) and P(i) transport, probably via their action on Ca(2+)-channels and Na(+)/P(i) co-transporter. At present, information about the sequence, expression and distribution of the STC receptor(s) is lacking. However, recent emerging evidence hints the involvement of STC1 and STC2 in the sub-cellular functions of mitochondria and endoplasmic reticulum respectively, particularly responding to oxidative stress and unfolded protein response. With increasing evidence that demonstrates the local actions of STCs, the focus of the research has been moved to cellular inflammation and carcinogenesis. This review integrates the information available on STCs in fish and mammals, focusing mainly on their embryonic origin, tissue distribution, their potential regulatory mechanisms and the modes of action, and their physiological and pathophysiological functions, particularly in cancer biology.

Assessment of stanniocalcin-1 as a prognostic marker in human esophageal squamous cell carcinoma

Stanniocalcin-1 (STC1) is a secreted glycoprotein hormone and highly expressed in various types of human malignancies. Although evidence points to the role of STC1 in human cancers, the clinical significance of STC1 expression in esophageal cancer has not been well established. Quantitative reverse transcriptase-polymerase chain reaction and immunohistochemistry were performed to assess the expression of STC1 in the cancer cell line TE8 and esophageal cancer tissues from 229 esophageal squamous cell carcinomas (ESCC). Surgically-resected tissue sections were immunostained for potential regulators of STC1 expression, hypoxia-inducible factor-1α (HIF-1α) and p53. Marked increase in STC1 mRNA and protein expression was noted in TE8 cells cultured under hypoxic conditions. Overexpression of STC1 mRNA was noted in ESCC tumors compared to normal counterparts. Positive immunohistochemical staining for STC1 protein was observed in 38.9% of patients, and correlated significantly with advanced pT status (P=0.019), poor prognosis [overall survival (P<0.0006) and disease-free survival (P<0.0002) of ESCC patients who had undergone curative surgery]. Positive staining for HIF-1α and p53 proteins in ESCC did not correlate with STC1 expression. The results showed marked induction of STC1 expression under hypoxia in cultured cells and in esophageal cancer cells and that overexpression of STC1 was an independent prognostic factor in patients with esophageal cancer who had undergone curative surgery. STC1 is a potentially useful biomarker for ESCC treatment.

Integrative genomic analyses of sporadic clear cell renal cell carcinoma define disease subtypes and potential new therapeutic targets

Sporadic clear cell renal cell carcinoma (ccRCC), the most common type of adult kidney cancer, is often associated with genomic copy number aberrations on chromosomes 3p and 5q. Aberrations on chromosome 3p are associated with inactivation of the tumor suppressor gene von-Hippel Lindau (VHL), which activates the hypoxia-inducible factors HIF1α and HIF2α. In contrast, ccRCC genes on chromosome 5q remain to be defined. In this study, we conducted an integrated analysis of high-density copy number and gene expression data for 54 sporadic ccRCC tumors that identified the secreted glycoprotein STC2 (stanniocalcin 2) and the proteoglycan VCAN (versican) as potential 5q oncogenes in ccRCCs. In functional assays, STC2 and VCAN each promoted tumorigenesis by inhibiting cell death. Using the same approach, we also investigated the two VHL-deficient subtypes of ccRCC, which express both HIF1α and HIF2α (H1H2) or only HIF2α (H2). This analysis revealed a distinct pattern of genomic aberrations in each group, with the H1H2 group displaying, on average, a more aberrant genome than the H2 group. Together our findings provide a significant advance in understanding ccRCCs by offering a molecular definition of two subtypes with distinct characteristics as well as two potential chromosome 5q oncogenes, the overexpression of which is sufficient to promote tumorigenesis by limiting cell death.

Sp1 is a transcription repressor to stanniocalcin-1 expression in TSA-treated human colon cancer cells, HT29

Our previous study demonstrated that, stanniocalcin-1 (STC1) was a target of histone deacetylase (HDAC) inhibitors and was involved in trichostatin A (TSA) induced apoptosis in the human colon cancer cells, HT29. In this study, we reported that the transcriptional factor, specificity protein 1 (Sp1) in association with retinoblastoma (Rb) repressed STC1 gene transcription in TSA-treated HT29 cells. Our data demonstrated that, a co-treatment of the cells with TSA and Sp1 inhibitor, mithramycin A (MTM) led to a marked synergistic induction of STC1 transcript levels, STC1 promoter (1 kb)-driven luciferase activity and an increase of apoptotic cell population. The knockdown of Sp1 gene expression in TSA treated cells, revealed the repressor role of Sp1 in STC1 transcription. Using a protein phosphatase inhibitor okadaic acid (OKA), an increase of Sp1 hyperphosphorylation and so a reduction of its transcriptional activity, led to a significant induction of STC1 gene expression. Chromatin immunoprecipitation (ChIP) assay revealed that Sp1 binding on STC1 proximal promoter in TSA treated cells. The binding of Sp1 to STC1 promoter was abolished by the co-treatment of MTM or OKA in TSA-treated cells. Re-ChIP assay illustrated that Sp1-mediated inhibition of STC1 transcription was associated with the recruitment of another repressor molecule, Rb. Collectively our findings identify STC1 is a downstream target of Sp1.

Stanniocalcin-1 regulates re-epithelialization in human keratinocytes

Stanniocalcin-1 (STC1), a glycoprotein hormone, is believed to be involved in various biological processes such as inflammation, oxidative responses and cell migration. Riding on these emerging evidences, we hypothesized that STC1 may participate in the re-epithelialization during wound healing. Re-epithelialization is a critical step that involves keratinocyte lamellipodia (e-lam) formation, followed by cell migration. In this study, staurosporine (STS) treatment induced human keratinocyte (HaCaT) e-lam formation on fibronectin matrix and migration via the activation of focal adhesion kinase (FAK), the surge of intracellular calcium level [Ca²⁺]i and the inactivation of Akt. In accompanied with these migratory features, a time- and dose-dependent increase in STC1 expression was detected. STC1 gene expression was found not the downstream target of FAK-signaling as illustrated by FAK inhibition using PF573228. The reduction of [Ca²⁺]i by BAPTA/AM blocked the STS-mediated keratinocyte migration and STC1 gene expression. Alternatively the increase of [Ca²⁺]i by ionomycin exerted promotional effect on STS-induced STC1 gene expression. The inhibition of Akt by SH6 and GSK3β by lithium chloride (LiCl) could respectively induce and inhibit the STS-mediated e-lam formation, cell migration and STC1 gene expression. The STS-mediated e-lam formation and cell migration were notably hindered or induced respectively by STC1 knockdown or overexpression. This notion was further supported by the scratched wound assay. Collectively the findings provide the first evidence that STC1 promotes re-epithelialization in wound healing.

Maintenance of hormone responsiveness in luminal breast cancers by suppression of Notch

Luminal breast cancers express estrogen (ER) and/or progesterone (PR) receptors and respond to hormone therapies. Basal-like "triple negative" cancers lack steroid receptors but are cytokeratin (CK) 5-positive and require chemotherapy. Here we show that more than half of primary ER(+)PR(+) breast cancers contain an ER(-)PR(-)CK5(+) "luminobasal" subpopulation exceeding 1% of cells. Starting from ER(+)PR(+) luminal cell lines, we generated lines with varying luminal to luminobasal cell ratios and studied their molecular and biological properties. In luminal disease, luminobasal cells expand in response to antiestrogen or estrogen withdrawal therapies. The phenotype and gene signature of the hormone-resistant cells matches that of clinical triple negative basal-like and claudin-low disease. Luminobasal cell expansion in response to hormone therapies is regulated by Notch1 signaling and can be blocked by γ-secretase inhibitors. Our data establish a previously unrecognized plasticity of ER(+)PR(+) luminal breast cancers that, without genetic manipulation, mobilizes outgrowth of hormone-resistant basal-like disease in response to treatment. This undesirable outcome can be prevented by combining endocrine therapies with Notch inhibition.

Identification of stromally expressed molecules in the prostate by tag-profiling of cancer-associated fibroblasts, normal fibroblasts and fetal prostate

The stromal microenvironment has key roles in prostate development and cancer, and cancer-associated fibroblasts (CAFs) stimulate tumourigenesis via several mechanisms including the expression of pro-tumourigenic factors. Mesenchyme (embryonic stroma) controls prostate organogenesis, and in some circumstances can re-differentiate prostate tumours. We have applied next-generation Tag profiling to fetal human prostate, normal human prostate fibroblasts (NPFs) and CAFs to identify molecules expressed in prostatic stroma. Comparison of gene expression profiles of a patient-matched pair of NPFs vs CAFs identified 671 transcripts that were enriched in CAFs and 356 transcripts whose levels were decreased, relative to NPFs. Gene ontology analysis revealed that CAF-enriched transcripts were associated with prostate morphogenesis and CAF-depleted transcripts were associated with cell cycle. We selected mRNAs to follow-up by comparison of our data sets with published prostate cancer fibroblast microarray profiles as well as by focusing on transcripts encoding secreted and peripheral membrane proteins, as well as mesenchymal transcripts identified in a previous study from our group. We confirmed differential transcript expression between CAFs and NPFs using QrtPCR, and defined protein localization using immunohistochemistry in fetal prostate, adult prostate and prostate cancer. We demonstrated that ASPN, CAV1, CFH, CTSK, DCN, FBLN1, FHL1, FN, NKTR, OGN, PARVA, S100A6, SPARC, STC1 and ZEB1 proteins showed specific and varied expression patterns in fetal human prostate and in prostate cancer. Colocalization studies suggested that some stromally expressed molecules were also expressed in subsets of tumour epithelia, indicating that they may be novel markers of EMT. Additionally, two molecules (ASPN and STC1) marked overlapping and distinct subregions of stroma associated with tumour epithelia and may represent new CAF markers.

Protein kinase Cα suppresses the expression of STC1 in MDA-MB-231 breast cancer cells

Several protein kinase C (PKC) isoforms have been shown to influence different cellular processes that may contribute to the malignancy of breast cancer cells. To obtain insight into mechanisms mediating the PKC effects, global gene expression was analyzed in MDA-MB-231 breast cancer cells in which PKCα, PKCδ or PKCε had been down-regulated with siRNA. Gene set enrichment analyses revealed that hypoxia-induced genes were enriched among genes that increased in PKCα-down-regulated cells. The STC1 mRNA, encoding stanniocalcin 1, was particularly up-regulated following depletion of PKCα and was also induced by hypoxia. Both hypoxia and PKCα down-regulation also led to increased STC1 protein levels. The results demonstrate that PKCα suppresses the expression of STC1 in breast cancer cells.