Proteomic identification of LASP-1 down-regulation after RNAi urokinase silencing in human hepatocellular carcinoma cells

Inhibition of GLUD1 mediated by LASP1 and SYVN1 contributes to hepatitis B virus X protein-induced hepatocarcinogenesis

Glutamate dehydrogenase 1 (GLUD1) is implicated in oncogenesis. However, little is known about the relationship between GLUD1 and hepatocellular carcinoma (HCC). In the present study, we demonstrated that the expression levels of GLUD1 significantly decreased in tumors, which was relevant to the poor prognosis of HCC. Functionally, GLUD1 silencing enhanced the growth and migration of HCC cells. Mechanistically, the upregulation of interleukin-32 through AKT activation contributes to GLUD1 silencing-facilitated hepatocarcinogenesis. The interaction between GLUD1 and AKT, as well as α-ketoglutarate regulated by GLUD1, can suppress AKT activation. In addition, LIM and SH3 protein 1 (LASP1) interacts with GLUD1 and induces GLUD1 degradation via the ubiquitin-proteasome pathway, which relies on the E3 ubiquitin ligase synoviolin (SYVN1), whose interaction with GLUD1 is enhanced by LASP1. In hepatitis B virus (HBV)-related HCC, the HBV X protein (HBX) can suppress GLUD1 with the participation of LASP1 and SYVN1. Collectively, our data suggest that GLUD1 silencing is significantly associated with HCC development, and LASP1 and SYVN1 mediate the inhibition of GLUD1 in HCC, especially in HBV-related tumors.

BMP2 downregulates urokinase-type plasminogen activator via p38 MAPK: Implications in C2C12 cells myogenic differentiation

Bone morphogenetic protein (BMP)2 strongly affects the differentiation program of myoblast cells by inhibiting myogenesis and inducing osteogenic differentiation. In turn, extracellular matrix (ECM) proteinases, such as urokinase-type plasminogen activator (uPA), can influence the fate of muscle stem cells by participating in ECM reorganization. Although both BMP2 and uPA have antagonistic roles in muscles cells differentiation, no connection between them has been elucidated so far. This study aims to determine whether BMP2 regulates uPA expression in the myogenic C2C12 cell line and its impact on muscle cell fate differentiation. Our results showed that BMP2 did not modify C2C12 cell proliferation in a growth medium or myogenic differentiation medium. Although BMP2 inhibited myogenesis and induced osteogenesis, these effects were achieved with different doses of BMP2. Low concentrations of BMP2 blocked myogenesis, while a higher concentration was needed to induce osteogenesis. Reduced uPA expression was noticed alongside myogenic inhibition at low concentrations of BMP2. BMP2 activated p38 MAPK signaling to inhibit uPA activity. Furthermore, ectopic human uPA expression reduced BMP2's ability to inhibit the myogenic differentiation of C2C12 cells. In conclusion, BMP2 inhibits uPA expression through p38 MAPK and in vitro myogenesis at non-osteogenic concentrations, while uPA ectopic expression prevents BMP2 from inhibiting myogenesis in C2C12 cells.

New Frontiers for the Cytoskeletal Protein LASP1

In the recent two decades, LIM and SH3 protein 1 (LASP1) has been developed from a simple actin-binding structural protein to a tumor biomarker and subsequently to a complex, nuclear transcriptional regulator. Starting with a brief historical perspective, this review will mainly compare and contrast LASP1 and LASP2 from the angle of the newest data and importantly, examine their role in transcriptional regulation. We will summarize the current knowledge through pictorial models and tables including the roles of different microRNAs in the differential regulation of LASP1 levels and patient outcome rather than specify in detail all tumor entities. Finally, the novel functional roles of LASP1 in secretion of vesicles, expression of matrix metalloproteinases and transcriptional regulation as well as the activation of survival and proliferation pathways in different cancer types are described.

HBX protein promotes LASP-1 expression through activation of c-Jun in human hepatoma cells

LIM and SH3 domain protein 1 (LASP-1) is known to participate in the progression of hepatocellular carcinoma (HCC). We previously showed that ectopic expression of hepatitis B virus (HBV) X protein (HBX) enhanced the expression of LASP-1, which promoted proliferation and migration of HCC cells. Here, we further demonstrated the molecular mechanism underlying upregulation of LASP-1, mediated by HBX, in HBV-infected HCC cells. Through a luciferase activity assay, we discovered that the LASP-1 promoter region regulated by HBX contained an AP-1 binding element in human hepatoma cells. Interestingly, c-Jun, one subunit of AP-1, was mainly responsible for activation, mediated by HBX, of the LASP-1 promoter. Furthermore, HBX was shown not only to interact with phosphorylated c-Jun in HCC cells but also to activate c-Jun by increasing the activation of PI3-K/JNK signaling. Chromatin immunoprecipitation (ChIP) assay demonstrated that HBX was capable of binding to the LASP-1 promoter with c-Jun. Further, the expression levels of HBX were shown to be significantly positively correlated with that of LASP-1 and phosphorylatedc-Jun in HBV-related HCC tissues by immunohistochemistry analysis. In addition, the N-terminus of HBX was found to be responsible for the activation of c-Jun, as well as the expression of LASP-1. Taken together, these results suggest that HBX contributes to LASP-1 expression via the activation of c-Jun to increase the promoter activity of LASP-1 in HBV-related HCC cells.

Regulation of matrix metalloproteinases (MMPs) expression and secretion in MDA-MB-231 breast cancer cells by LIM and SH3 protein 1 (LASP1)

The process of tumor invasion requires degradation of extracellular matrix by proteolytic enzymes. Cancer cells form protrusive invadopodia, which produce and release matrix metalloproteinases (MMPs) to degrade the basement membrane thereby enabling metastasis. We investigated the effect of LASP1, a newly identified protein in invadopodia, on expression, secretion and activation of MMPs in invasive breast tumor cell lines.

By analyzing microarray data of in-house generated control and LASP1-depleted MDA-MB-231 breast cancer cells, we observed downregulation of MMP1, -3 and -9 upon LASP1 depletion. This was confirmed by Western blot analysis. Conversely, rescue experiments restored in part MMP expression and secretion. The regulatory effect of LASP1 on MMP expression was also observed in BT-20 breast cancer cells as well as in prostate and bladder cancer cell lines.

In line with bioinformatic FunRich analysis of our data, which mapped a high regulation of transcription factors by LASP1, public microarray data analysis detected a correlation between high LASP1 expression and enhanced c-Fos levels, a protein that is part of the transcription factor AP-1 and known to regulate MMP expression. Compatibly, in luciferase reporter assays, AP-1 showed a decreased transcriptional activity after LASP1 knockdown.

Zymography assays and Western blot analysis revealed an additional promotion of MMP secretion into the extracellular matrix by LASP1, thus, most likely, altering the microenvironment during cancer progression.

The newly identified role of LASP1 in regulating matrix degradation by affecting MMP transcription and secretion elucidated the migratory potential of LASP1 overexpressing aggressive tumor cells in earlier studies.

Paving the path for invasion: The polyedric role of LASP1 in cancer

Although usually referred to as a structural actin-binding protein, LIM and SH3 domain-containing protein may actually be dynamically involved in the control of a wide spectrum of cellular processes, by virtue of its interaction with several molecular partners. Alongside being ubiquitously expressed in physiological conditions, LIM and SH3 domain-containing protein is overexpressed in a growing number of human cancers, in which it may actively contribute to their aggressiveness by promoting cell proliferation and migration. In view of the recent findings, implicating the protein in cancer progression, we discuss here the most relevant discoveries highlighting the role of this versatile protein in various human tumors. The correlation between LIM and SH3 domain-containing protein expression levels in cancer and the poor outcome and metastatic behavior of tumors denotes the clinical significance of this protein and hints its potential value as a new cancer prognostic or even diagnostic biomarker. This may be decisive not only to optimize existing pharmacological regimes but also to delineate novel, more efficacious therapeutic and/or preventive approaches.

Bioinformatics analysis of the proteins interacting with LASP-1 and their association with HBV-related hepatocellular carcinoma

LIM and SH3 domain protein (LASP-1) is responsible for the development of several types of human cancers via the interaction with other proteins; however, the precise biological functions of proteins interacting with LASP-1 are not fully clarified. Although the role of LASP-1 in hepatocarcinogenesis has been reported, the implication of LASP-1 interactors in HBV-related hepatocellular carcinoma (HCC) is not clearly evaluated. We obtained information regarding LASP-1 interactors from public databases and published studies. Via bioinformatics analysis, we found that LASP-1 interactors were related to distinct molecular functions and associated with various biological processes. Through an integrated network analysis of the interaction and pathways of LASP-1 interactors, cross-talk between different proteins and associated pathways was found. In addition, LASP-1 and several its interactors are significantly altered in HBV-related HCC through microarray analysis and could form a complex co-expression network. In the disease, LASP-1 and its interactors were further predicted to be regulated by a complex interaction network composed of different transcription factors. Besides, numerous LASP-1 interactors were associated with various clinical factors and related to the survival and recurrence of HBV-related HCC. Taken together, these results could help enrich our understanding of LASP-1 interactors and their relationships with HBV-related HCC.

LIM and SH3 protein 1 promotes tumor proliferation and metastasis in lung carcinoma

Lung cancer is the most frequently diagnosed cancer and the leading cause of cancer-related mortality worldwide. In the present study, we focused on LIM and SH3 protein 1 (LASP-1), a key molecule involved in the development of multiple cancers, and attempted to elucidate its effect on the oncogenesis of lung cancer. We determined the expression level of LASP-1 in lung cancer using reverse transcription-quantitative polymerase chain reaction and western blot analysis, and also studied the potential function of LASP-1 in lung cancer cell growth, apoptosis and migration by small interfering RNA transfection. The results revealed that the levels of LASP-1 mRNA and protein were abnormally high in lung cancer cells. Following RNA interference of LASP-1, the proliferation and migration ability of the human cancer cell line A549 were significantly decreased. In addition, fluorescence-activated cell sorting analysis indicated that the apoptotic process in the A549 cell line was induced by the silencing of LASP-1. Our study is the first to investigate the potential of LASP-1 in lung cancer, and revealed its significant role in regulating the growth and metastasis of lung cancer cells. The present study suggests that LASP-1 has potential as a therapeutic target in the treatment of lung cancer in the clinic.

Suppression of LASP-1 attenuates the carcinogenesis of prostatic cancer cell lines: Key role of the NF-κB pathway

Prostate cancer (PCa) is one of the most frequently diagnosed cancers among males worldwide and causes a considerable number of deaths each year. One of the newly explored targets for the development of therapies against PCa is LIM and SH3 protein 1 (LASP-1). In the present study, the function of LASP-1 in the oncogenesis and metastasis of PCa was investigated using a series of in vitro experiments. Moreover, the mechanism through which LASP-1 exerted its effect on the carcinogenesis of PCa was also explored. The expression levels of LASP-1 in clinical PCa specimens were determined both at the mRNA and protein levels. Afterwards, the activity of LASP-1 in human PCa cell lines PC3 and DU145 was inhibited using a short hairpin RNA (shRNA) interfering method. The effects of LASP-1 knockdown on the cell growth, apoptosis, cell cycle distribution, migration and invasion were assessed. It was demonstrated that the expression of LASP-1 was significantly higher in the clinical PCa tissues than the level in the corresponding para-carcinoma tissues. Following the knockdown of the LASP-1 gene in human PCa cell lines, the viability, migration and invasion of the cancer cells were decreased. It was also demonstrated that the change in the cell viability and motile ability were associated with an induction of cell apoptosis and G1 phase cell cycle arrest. Based on the results of the detection of the expression of NF-κB-related factors, it was indicated that LASP-1 may affect the carcinogenesis of PCa through a NF-κB inhibition-dependent manner. Although the detailed explanation of the mechanism of LASP-1 in the carcinogenesis of PCa requires further elucidation, the present study highlights the potential of LASP-1 as a promising therapeutic target to ameliorate the oncogenesis and metastasis of PCa.

Applicability of Under Vacuum Fresh Tissue Sealing and Cooling to Omics Analysis of Tumor Tissues

CONTEXT

Biobanks of frozen human normal and malignant tissues represent a valuable source for "omics" analysis in translational cancer research and molecular pathology. However, the success of molecular and cellular analysis strongly relies on the collection, handling, storage procedures, and quality control of fresh human tissue samples.

OBJECTIVE

We tested whether under vacuum storage (UVS) effectively preserves tissues during the time between surgery and storage for "omics" analyses.

DESIGN

Normal and matched tumor specimens, obtained from 16 breast, colon, or lung cancer patients and 5 independent mesenchymal tumors, were dissected within 20 minutes from surgical excision and divided in three to five aliquots; for each tissue sample, one aliquot was snap-frozen in liquid nitrogen (defined as baseline or T0 samples), and the other portions were sealed into plastic bags and kept at 4°C for 1, 24, 48, or 72 hours under vacuum and then frozen. The tissue and molecular preservation under vacuum was evaluated over time in terms of histomorphology, transcription (Illumina microarrays), protein (surface-enhanced laser desorption/ionization-time of flight/mass spectrometry and Western blot), and metabolic profile (nuclear magnetic resonance spectroscopy).

RESULTS

Tissue morphology, Mib-1, and vimentin immunostaining were preserved over time without signs of tissue degradation. Principal variance component analysis showed that time of storage had a minimal effect on gene expression or the proteome, but affected the preservation of some metabolites to a greater extent. UVS did not impact the RNA and protein integrity or specific phosphorylation sites on mTOR and STAT3. Measurement of metabolites revealed pronounced changes after 1 hour of storage.

CONCLUSIONS

Our results show that UVS can preserve tissue specimens for histological, transcriptomic, and proteomic examinations up to 48 hours and possibly longer, whereas it has limitations for metabolomic applications.

Identification of the transcriptional regulators by expression profiling infected with hepatitis B virus

BACKGROUND

The molecular pathogenesis of infection by hepatitis B virus with human is extremely complex and heterogeneous. To date the molecular information is not clearly defined despite intensive research efforts. Thus, studies aimed at transcription and regulation during virus infection or combined researches of those already known to be beneficial are needed.

AIMS

With the purpose of identifying the transcriptional regulators related to infection of hepatitis B virus in gene level, the gene expression profiles from some normal individuals and hepatitis B patients were analyzed in our study.

METHODS

In this work, the differential expressed genes were selected primarily. The several genes among those were validated in an independent set by qRT-PCR. Then the differentially co-expression analysis was conducted to identify differentially co-expressed links and differential co-expressed genes. Next, the analysis of the regulatory impact factors was performed through mapping the links and regulatory data. In order to give a further insight to these regulators, the co-expression gene modules were identified using a threshold-based hierarchical clustering method. Incidentally, the construction of the regulatory network was generated using the computer software.

RESULTS

A total of 137,284 differentially co-expressed links and 780 differential co-expressed genes were identified. These co-expressed genes were significantly enriched inflammatory response. The results of regulatory impact factors revealed several crucial regulators related to hepatocellular carcinoma and other high-rank regulators. Meanwhile, more than one hundred co-expression gene modules were identified using clustering method.

CONCLUSIONS

In our study, some important transcriptional regulators were identified using a computational method, which may enhance the understanding of disease mechanisms and lead to an improved treatment of hepatitis B. However, further experimental studies are required to confirm these findings.

An update on the LIM and SH3 domain protein 1 (LASP1): a versatile structural, signaling, and biomarker protein

The gene encoding the LIM and SH3 domain protein (LASP1) was cloned two decades ago from a cDNA library of breast cancer metastases. As the first protein of a class comprising one N-terminal LIM and one C-terminal SH3 domain, LASP1 founded a new LIM-protein subfamily of the nebulin group. Since its discovery LASP1 proved to be an extremely versatile protein because of its exceptional structure allowing interaction with various binding partners, its ubiquitous expression in normal tissues, albeit with distinct expression patterns, and its ability to transmit signals from the cytoplasm into the nucleus. As a result, LASP1 plays key roles in cell structure, physiological processes, and cell signaling. Furthermore, LASP1 overexpression contributes to cancer aggressiveness hinting to a potential value of LASP1 as a cancer biomarker.

In this review we summarize published data on structure, regulation, function, and expression pattern of LASP1, with a focus on its role in human cancer and as a biomarker protein. In addition, we provide a comprehensive transcriptome analysis of published microarrays (n=2,780) that illustrates the expression profile of LASP1 in normal tissues and its overexpression in a broad range of human cancer entities.

Molecular characterization of LASP-1 expression reveals vimentin as its new partner in human hepatocellular carcinoma cells

Hepatocellular carcinoma (HCC) is the third most common cause of cancer-related mortality worldwide. We have previously reported that LASP-1 is a downstream protein of the urokinase type plasminogen activator (uPA). Here we investigated the role of LASP-1 in HCC by a molecular and biological characterization of LASP-1 expression in human HCC specimens and in cultured HCC cells. We determined the LASP-1 mRNA expression levels in 55 HCC cases with different hepatic background disease. We identified 3 groups of patients with high, equal or low LASP-1 mRNA levels in HCC tissues compared to the peritumoral (PT) tissues. In particular we found that i) the HCCs displayed a higher LASP-1 mRNA level in HCC compared to PT tissues; ii) the expression levels of LASP-1 mRNA in female HCCs were significantly higher compared to male HCCs; iii) the cirrhotic HCCs displayed a higher LASP-1 mRNA. Further, the biological characterization of the ectopic LASP-1 overexpression in HCC cells, using MALDI-TOF mass spectrometer on the LASP-1 co-immunoprecipitated fractions, displayed vimentin as a novel putative partner of LASP-1. Our results suggest that LASP-1 mRNA overexpression may be mainly implicated in female HCCs and cirrhotic HCCs; and that LASP1 may play its role with vimentin in HCC cells.

LASP-1 promotes tumor proliferation and metastasis and is an independent unfavorable prognostic factor in gastric cancer

PURPOSE

The LIM and SH3 protein 1 (LASP-1) is a focal adhesion protein, and its expression has been reported to be increased in many malignant tumors. However, the role of LASP-1 in gastric cancer is still unknown. The aim of this study was to determine the relationship of LASP-1 expression with the progression and prognosis of gastric cancer.

METHODS

Expression of LASP-1 was evaluated in gastric cancer tissues and cell lines by immunohistochemistry and Western blot analysis. The relationship between LASP-1 expression and clinicopathological characteristics was analyzed. Using RNA interference, the effects of LASP-1 on cell proliferation, migration and invasion were investigated in gastric cancer cell lines both in vitro and in vivo.

RESULTS

The LASP-1 was overexpressed in gastric cancer tissues and cell lines. LASP-1 expression was significantly associated with tumor size, invasive depth, TNM stage, lymph node metastasis and p53 expression (all P < 0.05). Multivariate survival analysis showed that LASP-1 expression was recognized as an independent prognostic factor of patient's survival. Knockdown of LASP-1 inhibited cell proliferation, migration and invasion in vitro as well as tumorigenesis and metastasis in vivo.

CONCLUSIONS

Our study showed that LASP-1, overexpressed in gastric cancer and associated with poor prognosis, plays an important role in the growth and metastasis of gastric cancer.

LIM and SH3 protein 1, a promoter of cell proliferation and migration, is a novel independent prognostic indicator in hepatocellular carcinoma

LIM and SH3 protein 1 (LASP-1) plays a significant role in the formation of several malignant tumours. However, the biological and clinical significances of LASP-1 in hepatocellular carcinoma (HCC) remain largely unknown. Using immunohistochemistry, we analysed LASP-1 expression in 144 clinicopathologically characterised HCC cases. Using gene and transfection and RNA interference, we investigated the effects of LASP-1 overexpression and depletion on tumour cellular behaviour in vitro. LASP-1 expression was detected in not only cytoplasm and but also nucleus of HCC and liver cells. The positive rates of both cytosolic and nuclear LASP-1 expression in HCC were higher than adjacent non-tumourous tissues. Statistical analysis showed that heterogeneous LASP-1 expression is associated with hepatitis B surface antigen (HBsAg) and serum alpha-fetoprotein (AFP) level of HCC patients. A significant trend was identified between cytosolic LASP-1 overexpression in HCC and worsening clinical prognosis. Multivariate survival analysis showed that cytosolic LASP-1 expression was recognised as an independent prognostic factor of patient's survival. In vitro study showed LASP-1 promoted cell proliferation and migration, and resulted in aggressive phenotypes of cancer cells. LASP-1 is a valuable marker of HCC progression. High cytosolic LASP-1 expression is associated with poor overall survival in HCC patients.

Role of hepatitis B virus X protein in regulating LIM and SH3 protein 1 (LASP-1) expression to mediate proliferation and migration of hepatoma cells

BACKGROUND

Hepatitis B virus X protein (HBx) has been shown to be responsible for the development of hepatocellular carcinoma (HCC) caused by Hepatitis B virus infection. However, its potential effect on the progression of hepatocellular carcinoma remains yet unclear. LIM and SH3 protein 1 (LASP-1), a focal adhesion protein, is expressed in an up-regulation manner in the HCC tissues. LASP-1 plays an important role in the regulation of proliferation and migration of HCC. In this study, we investigated the effect of LASP-1 involved in HBx-related tumor progression.

METHODS

LASP-1 levels in the HBx stable transfected HepG2 and Huh-7 cells were detected by RT-PCR and western blot analysis. The cellular localization of LASP-1 was assessed by immunofluorescence analysis. The activity of phosphatidylinositol 3-kinase (PI3-K) pathway was demonstrated by western blot assay. The HBx-expressing cells were transfected with specific small interference RNA (siRNA) against LASP-1. The proliferation and migration ability of cells were evaluated by cell viability assay and plate clone formation assay. The migration ability of cells was detected by transwell assay and wound healing assay.

RESULTS

RT-PCR and western blot analysis indicated the expression of LASP-1 was increased in the stable HBx-expressing cells compared with the control cells. Immunofluorescence study revealed that the distributions of LASP-1 in HepG2-HBX cells were mainly in pseudopods and the cytoplasm while they were mainly localized in the cytoplasm of HepG2-Mock cells. The cellular localizations of LASP-1 in Huh-7-HBX cells were in the perinuclear fractions while they were mainly localized in the cytoplasm of Huh-7-Mock cells. The upregulation of LASP-1 was inhibited after treatment with LY294002, PI3-K pathway inhibitor. Overexpression of LASP-1 in the stable HBx-expressing cells enhanced the proliferation and migration ability of hepatocellular cells. siRNA-mediated LASP-1 knowdown in the stable HBx-expressing cells significantly suppressed hepatocellular cells proliferation and migration.

CONCLUSIONS

These results demonstrated that HBx could upregulate LASP-1 through PI3-K pathway to promote the proliferation and migration of hepatoma cells.

The interconnectedness of cancer cell signaling

The elegance of fundamental and applied research activities have begun to reveal a myriad of spatial and temporal alterations in downstream signaling networks affected by cell surface receptor stimulation including G protein-coupled receptors and receptor tyrosine kinases. Interconnected biochemical pathways serve to integrate and distribute the signaling information throughout the cell by orchestration of complex biochemical circuits consisting of protein interactions and covalent modification processes. It is clear that scientific literature summarizing results from both fundamental and applied scientific research activities has served to provide a broad foundational biologic database that has been instrumental in advancing our continued understanding of underlying cancer biology. This article reflects on historical advances and the role of innovation in the competitive world of grant-sponsored research.

Cell Adhesion and Transcriptional Activity - Defining the Role of the Novel Protooncogene LPP

Integrating signals from the extracellular matrix through the cell surface into the nucleus is an essential feature of metazoan life. To date, many signal transducers known as shuttle proteins have been identified to act as both a cytoskeletal and a signaling protein. Among them, the most prominent representatives are zyxin and lipoma preferred (translocation) partner (LPP). These proteins belong to the LIM domain protein family and are associated with cell migration, proliferation, and transcription. LPP was first identified in benign human lipomas and was subsequently found to be overexpressed in human malignancies such as lung carcinoma, soft tissue sarcoma, and leukemia. This review portrays LPP in the context of human neoplasia based on a study of the literature to define its important role as a novel protooncogene in carcinogenesis.

Dinosaurs and ancient civilizations: reflections on the treatment of cancer

Research efforts in the area of palaeopathology have been seen as an avenue to improve our understanding of the pathogenesis of cancer. Answers to questions of whether dinosaurs had cancer, or if cancer plagued ancient civilizations, have captured the imagination as well as the popular media. Evidence for dinosaurian cancer may indicate that cancer may have been with us from the dawn of time. Ancient recorded history suggests that past civilizations attempted to fight cancer with a variety of interventions. When contemplating the issue why a generalized cure for cancer has not been found, it might prove useful to reflect on the relatively limited time that this issue has been an agenda item of governmental attention as well as continued introduction of an every evolving myriad of manmade carcinogens relative to the total time cancer has been present on planet Earth. This article reflects on the history of cancer and the progress made following the initiation of the "era of cancer chemotherapy."

Nuclear localisation of LASP-1 correlates with poor long-term survival in female breast cancer

BACKGROUND

LIM and SH3 protein 1 (LASP-1) is a nucleo-cytoplasmatic signalling protein involved in cell proliferation and migration and is upregulated in breast cancer in vitro studies have shown that LASP-1 might be regulated by prostate-derived ETS factor (PDEF), p53 and/or LASP1 gene amplification. This current study analysed the prognostic significance of LASP-1 on overall survival (OS) in 177 breast cancer patients and addressed the suggested mechanisms of LASP-1-regulation.

METHODS

Nucleo-cytoplasmatic LASP-1-positivity of breast carcinoma samples was correlated with long-term survival, clinicopathological parameters, Ki67-positivity and PDEF expression. Rate of LASP1 amplification was determined in micro-dissected primary breast cancer cells using quantitative RT-PCR. Cell-phase dependency of nuclear LASP-1-localisation was studied in synchronised cells. In addition, LASP-1, PDEF and p53 expression was compared in cell lines of different tumour entities to define principles for LASP-1-regulation.

RESULTS

We showed that LASP-1 overexpression is not due to LASP1 gene amplification. Moreover, no correlation between p53-mutations or PDEF-expression and LASP-1-status was observed. However, nuclear LASP-1-localisation in breast carcinomas is increased during proliferation with peak in G2/M-phase and correlated significantly with Ki67-positivity and poor OS.

CONCLUSION

Our results provide evidence that nuclear LASP-1-positivity may serve as a negative prognostic indicator for long-term survival of breast cancer patients.

The War on Cancer rages on

In 1971, the "War on Cancer" was launched by the US government to cure cancer by the 200-year anniversary of the founding of the United States of America, 1976. This article briefly looks back at the progress that has been made in cancer research and compares progress made in other areas of human affliction. While progress has indeed been made, the battle continues to rage on.

Lasp1 gene disruption is linked to enhanced cell migration and tumor formation

Lasp1 is an actin-binding, signaling pathway-regulated phosphoprotein that is overexpressed in several cancers. siRNA knockdown in cell lines retards cell migration, suggesting the possibility that Lasp1 upregulation influences cancer metastasis. Herein, we utilized a recently developed gene knockout model to assess the role of Lasp1 in modulating nontransformed cell functions. Wound healing and tumor initiation progressed more rapidly in Lasp1(-/-) mice compared with Lasp1(+/+) controls. Embryonic fibroblasts (MEFs) derived from Lasp1(-/-) mice also migrated more rapidly in vitro. These MEFs characteristically possessed increased focal adhesion numbers and displayed more rapid attachment compared with wild-type MEFs. Differential microarray analyses revealed alterations in message expression for proteins implicated in cell migration, adhesion, and cytoskeletal organization. Notably, the focal adhesion protein, lipoma preferred partner (LPP), a zyxin family member and putative Lasp1 binding protein, was increased about twofold. Because LPP gene disruption reduces cell migration, we hypothesize that LPP plays a role in enhancing the migratory capacity of Lasp1(-/-) MEFs, perhaps by modifying the subcellular localization of other motility-associated proteins. The striking contrast in the functional effects of loss of Lasp1 in innate cells compared with cell lines reveals distinct differences in mechanisms of motility and attachment in these models.