S100P In Cells Research Articles

Promotion of the occurrence of endometrioid carcinoma by S100 calcium binding protein P

BackgroundEndometrial cancer, one of the most common malignant tumors, is a serious threat to women’s health. Endometrial hyperplasia is a precursor of endometrial cancer. S100 calcium binding protein P (S100P) has been found to play important roles in many types of cancer. The present study aimed to investigate the expression of S100P in endometrial cancer and its precursor lesions, and to explore the possible mechanisms.MethodsWe collected paraffin sections of normal endometrium, simple and complex non-atypical hyperplasia, atypical hyperplasia, and endometrioid carcinoma. The expression of S100P in endometrial cancer and its precancerous lesions was observed using immunohistochemistry. We also cultured primary endometrial cells and endometrial cancer cell lines (Ishikawa and RL95–2), and observed the expression of S100P in these cells. Laser confocal microscopy was used to observe the co-localization of S100P and its interacting protein Ezrin in RL95–2 cells. We employed lentiviruses to knockdown and overexpress S100P and then detected the F-actin distribution and cell invasion using phalloidin staining and Transwell assays.ResultsThere was a gradual increase in the S100P signal as the disease progressed from normal endometrium and simple non-atypical hyperplasia, to complex non-atypical hyperplasia, atypical hyperplasia, and then to endometrial cancer. S100P was mainly distributed in the cytoplasm and co-localized with Ezrin in endometrial cancer cells. After knocking down S100P, F-actin aggregated in the nucleus or to the local cell membrane. Furthermore, knockdown of S100P in Ishikawa cells decreased their cell invasion capability. Meanwhile, S100P overexpression in endometrial stromal cells increased cell invasion.ConclusionsThese data suggested that S100P might be involved in the occurrence and development of endometrial cancer via interaction with Ezrin and re-organization of F-actin to promote cell invasion.

Abstract 2997: Upregulation of S100P by caveolin-1 drives tumorigenesis and metastasis in hepatocellular carcinoma under hypoxic stress

Abstract Hypoxia is a common feature of hepatocellular carcinoma (HCC) due to the expansion of tumors and the inadequacy of their local vasculature and facilitates tumor metastasis. Our previous study revealed that high level of Caveolin-1 (Cav1) was exclusively expressed in primary HCC and metastatic tissues and its level was further enhanced under hypoxic stress. Suppression of Cav1 reduced HCC growth and metastasis. This suggests that Cav1 may play an important role in the acquisition of aggressiveness in cancer cells under hypoxic stress. To explore the molecular mechanisms by which Cav1 mediates HCC cell motility and invasiveness, a cDNA microarray analysis was employed to compare the gene expression profiles between sh-Cav1 knockdown cells and the control sh-Ctl cells. Among the differentially expressed genes, the expression of S100P, a member of the S100 calcium-binding protein family showed a 4-fold reduction. S100P has been shown to be highly expressed in several malignancies and to promote metastasis. However, the impact of S100P on HCC tumorigenesis and metastasis remains unexplored and the potential role of S100P in human cancers under hypoxic stress has never been reported. Our present study aims to investigate the functional role of Cav1-mediated S100P signaling cascade in HCC tumorigenesis and metastasis under hypoxic condition. We showed that S100P expression was well correlated with Cav1 expression in a panel of HCC cell lines by Western Blot. Both proteins were undetectable in non-tumorigenic immortalized liver cell and moderately expressed in non-metastatic HCC cell line but pronouncedly expressed in metastatic HCC cell line. In addition, S100P expression at protein and mRNA levels was largely suppressed in sh-Cav1 stable knockdown cell. Suppression of S100P expression largely inhibited tumorigenesis in subcutaneous injection and orthotopic liver implantation models. Furthermore, hypoxia significantly enhanced the migration and invasion of control and such enhancement was not prominent when Cav1 was suppressed in Cav1 knockdown stable clones. Same phenomenon was also noticed in S100P knockdown stable clones. Taking together, Cav1 functions as the upstream component of S100P and plays a critical role in modulation of cell motility during hypoxia. Thereafter, we examined the potential signaling underlying Cav1-modulatedS100P expression in HCC development. Our data showed Cav1 was able to activate NF-κB reporter. Transient expression of Cav1 upregulated S100P in cells and the addition of NF-κB inhibitor, IMD-0354 abolished the upregulation of S100P by Cav1 suggests that Cav1 upregulates S100P via the activation of NF-κB pathway. In conclusion, Cav1 may upregulate S100P through the activation of NF-κB cascade to confer the enhanced aggressiveness of HCC cells under hypoxic condition. Citation Format: Xiaowen Mao, Sivia Yuen-sze Wong, Frankie Chi Fat Ko, Judy Wai Ping Yam. Upregulation of S100P by caveolin-1 drives tumorigenesis and metastasis in hepatocellular carcinoma under hypoxic stress. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 2997. doi:10.1158/1538-7445.AM2015-2997

P0017 S100P regulates cytoskeleton dynamics to promote cell migration and metastasis

Background S100P is an EF-hand calcium-binding protein. Like S100A4 and S100A6, S100P is expressed at a high level in cancers, particularly in those of the prostate, pancreas, and breast. We have demonstrated that S100P is a metastasis-inducing protein and that its upregulation enhances cell migration. When studying the molecular mechanisms, we found that S100P interacts separately with two major components of cytoskeleton, non-muscle myosin IIA (NMIIA) and tubulin. The aim of this study was to understand how S100P enhances cell migration through these protein interactions. Methods S100P-inducible cell lines and specific siRNAs were used to control the expression of S100P in cells. We used specific chemicals to disrupt actin stress fibres and microtubules and peptides to block the protein interactions. Results S100P differentially regulates NMIIA and NMIIB filaments, which reduced cell adhesion and enhanced cell migration. This process involves Rho, RAC1, and focal adhesion kinase. S100P upregulation simultaneously altered the dynamics of tubulin polymerisation to facilitate cell migration. Interpretation S100P directly regulates the dynamics of both actin-myosin filaments and microtubules, and the co-regulation of these cytoskeletons may synergistically enhance cell migration and promote cancer cell metastasis.

Glucocorticoid receptor‐mediated transcriptional activation of S100P gene coding for cancer‐related calcium‐binding protein

S100P is a member of the S100 family of calcium-binding proteins involved in calcium sensing and signal transduction. Its abnormal expression and biological activities are linked to tumor phenotype, namely to increased survival, proliferation, invasion and metastatic propensity of tumor cells. Association of S100P with outcome of tumor treatment and preliminary data from S100P promoter analysis prompted us to study regulation of S100P expression by glucocorticoids, which are implicated in tumor response to chemotherapy. We showed that dexamethasone (DX), a representative glucocorticoid, was capable to induce activity of S100P promoter by means of increased expression, nuclear translocation, and transactivation properties of the glucocorticoid receptor (GR). Moreover, DX treatment led to decreased phosphorylation of ERK1/2, reduced transcriptional activity of AP1, and modulated activity of some additional transcription factors. We identified a promoter region responsible for DX-mediated transactivation and proved GR binding to S100P promoter. We found that the effect of DX was enhanced by partial but not complete inhibition of the MAPK/ERK pathway, supporting an active crosstalk between GR and MAPK/ERK signal transduction in control of S100P expression. On the other hand, suppression of GR mRNA level by transient siRNA expression resulted in reduced S100P transcription. The role of GR activation in S100P regulation was supported by co-expression of GR with S100P in cells treated with DX. These data suggest that S100P is a direct transcriptional target of glucocorticoid-mediated signaling in tumor cells that is activated through the interplay of GR and MAPK pathways.

Interleukin-6 is a potent inducer of S100P, which is up-regulated in androgen-refractory and metastatic prostate cancer

Elevated circulating interleukin-6 (IL6) and up-regulated S100P in prostate cancer (PCa) specimens correlate independently with progression to androgen-independent and metastatic PCa. The cause of up-regulated S100P levels in advanced PCa remains to be determined. We investigated the possibility that IL6 is an inducer of S100P. Determination of mRNA and protein levels by real-time PCR and Western blotting revealed that IL6 is a more potent inducer of S100P than the synthetic androgen, R1881, in the LNCaP/C4-2B model of PCa progression. IL6 did not require androgen to induce S100P in these cells, which express a functional androgen receptor (AR). Like R1881, IL6 was unable to induce S100P in PC3 cells that lack a functional AR. IL6 did not strongly induce the AR-dependent genes PSA and KLK2 and, contrary to R1881, down-regulated Cyr61/CCN1, a potential marker that is down-regulated in PCa. Epidermal growth factor (EGF), which like IL6 is a non-androgen activator of the AR, did not induce S100P. The data identifies a unique gene-induction profile for IL6 and suggests that IL6 may require a functional AR for S100P induction. A link between elevated IL6 and up-regulated S100P in androgen-refractory and metastatic PCa is postulated.

Caspase-mediated cleavage is not required for the activity of presenilins in amyloidogenesis and NOTCH signaling.

The Alzheimer's disease (AD) associated presenilin (PS) proteins are proteolytically processed. One of the processing pathways involves cleavage by caspases. Pharmacological inhibition of caspases is currently being discussed as a treatment for a variety of neurodegenerative diseases, including AD. We therefore inhibited caspase mediated processing of PS-1 and PS-2 in cells transfected with wt and mutant PS by mutagenizing the substrate recognition site or by using specific peptide aldehydes known to block caspases. We found that the inhibition of caspase mediated processing of PS proteins does not decrease its amyloidogenic activity. PS cDNA constructs with mutations in the caspase cleavage site are biologically active in Caenorhabditis elegans such as the wt human PS proteins, demonstrating that caspase-mediated cleavage is not required for the physiological PS function in NOTCH signaling.