Genome-wide expression analysis of therapy-resistant tumors reveals SPARC as a novel target for cancer therapy

HDAC10 inhibition represses melanoma cell growth and BRAF inhibitor resistance via upregulating SPARC expression

Secreted protein acidic and rich in cysteine (SPARC), a conserved secreted glycoprotein, plays crucial roles in regulating various biological processes. SPARC is highly expressed and has profound implications in several cancer types, including melanoma. Understanding the mechanisms that govern SPARC expression in cancers has the potential to lead to improved cancer diagnosis, prognosis, treatment strategies, and patient outcomes. Here, we demonstrate that histone deacetylase 10 (HDAC10) is a key regulator of SPARC expression in melanoma cells. Depletion or inhibition of HDAC10 upregulates SPARC expression, whereas overexpression of HDAC10 downregulates it. Mechanistically, HDAC10 coordinates with histone acetyltransferase p300 to modulate the state of acetylation of histone H3 at lysine 27 (H3K27ac) at SPARC regulatory elements and the recruitment of bromodomain-containing protein 4 (BRD4) to these regions, thereby fine-tuning SPARC transcription. HDAC10 depletion and resultant SPARC upregulation repress melanoma cell growth primarily by activating AMPK signaling and inducing autophagy. Moreover, SPARC upregulation due to HDAC10 depletion partly accounts for the resensitization of resistant cells to a BRAF inhibitor. Our work reveals the role of HDAC10 in gene regulation through indirect histone modification and suggests a potential therapeutic strategy for melanoma or other cancers by targeting HDAC10 and SPARC.

HDAC10 blockade upregulates SPARC expression thereby repressing melanoma cell growth and BRAF inhibitor resistance

Secreted Protein Acidic and Rich in Cysteine (SPARC), a highly conserved secreted glycoprotein, is crucial for various bioprocesses. Here we demonstrate that histone deacetylase 10 (HDAC10) is a key regulator of SPARC expression. HDAC10 depletion or inhibition upregulates, while overexpression of HDAC10 downregulates, SPARC expression. Mechanistically, HDAC10 coordinates with histone acetyltransferase p300 to modulate the acetylation state of histone H3 lysine 27 (H3K27ac) at SPARC regulatory elements and the recruitment of bromodomain-containing protein 4 (BRD4) to these regions, thereby tuning SPARC transcription. HDAC10 depletion and resultant SPARC upregulation repress melanoma cell growth, primarily by induction of autophagy via activation of AMPK signaling. Moreover, SPARC upregulation due to HDAC10 depletion partly accounts for the resensitivity of resistant cells to a BRAF inhibitor. Our work reveals the role of HDAC10 in gene regulation through epigenetic modification and suggests a potential therapeutic strategy for melanoma or other cancers by targeting HDAC10 and SPARC.

Highlights

HDAC10 is the primary HDAC member that tightly controls SPARC expression. HDAC10 coordinates with p300 in modulating the H3K27ac state at SPARC regulatory elements and the recruitment of BRD4 to these regions. HDAC10 depletion and resultant SPARC upregulation inhibit melanoma cell growth by inducing autophagy via activation of AMPK signaling.SPARC upregulation as a result of HDAC10 depletion resensitizes resistant cells to BRAF inhibitors.

A Predictive Model of Adaptive Resistance to BRAF/MEK Inhibitors in Melanoma

The adaptive acquisition of resistance to BRAF and MEK inhibitor-based therapy is a common feature of melanoma cells and contributes to poor patient treatment outcomes. Leveraging insights from a proteomic study and publicly available transcriptomic data, we evaluated the predictive capacity of a gene panel corresponding to proteins differentially abundant between treatment-sensitive and treatment-resistant cell lines, deciphering predictors of treatment resistance and potential resistance mechanisms to BRAF/MEK inhibitor therapy in patient biopsy samples. From our analysis, a 13-gene signature panel, in both test and validation datasets, could identify treatment-resistant or progressed melanoma cases with an accuracy and sensitivity of over 70%. The dysregulation of HMOX1, ICAM, MMP2, and SPARC defined a BRAF/MEK treatment-resistant landscape, with resistant cases showing a >2-fold risk of expression of these genes. Furthermore, we utilized a combination of functional enrichment- and gene expression-derived scores to model and identify pathways, such as HMOX1-mediated mitochondrial stress response, as potential key drivers of the emergence of a BRAF/MEK inhibitor-resistant state in melanoma cells. Overall, our results highlight the utility of these genes in predicting treatment outcomes and the underlying mechanisms that can be targeted to reduce the development of resistance to BRAF/MEK targeted therapy.

The multifaceted role of Matricellular Proteins in health and cancer, as biomarkers and therapeutic targets

The extracellular matrix (ECM) is composed of a mesh of proteins, proteoglycans, growth factors, and other secretory components. It constitutes the tumor microenvironment along with the endothelial cells, cancer-associated fibroblasts, adipocytes, and immune cells. The proteins of ECM can be functionally classified as adhesive proteins and matricellular proteins (MCP). In the tumor milieu, the ECM plays a major role in tumorigenesis and therapeutic resistance. The current review encompasses thrombospondins, osteonectin, osteopontin, tenascin C, periostin, the CCN family, laminin, biglycan, decorin, mimecan, and galectins. The matrix metalloproteinases (MMPs) are also discussed as they are an integral part of the ECM with versatile functions in the tumor stroma. In this review, the role of these proteins in tumor initiation, growth, invasion and metastasis have been highlighted, with emphasis on their contribution to tumor therapeutic resistance. Further, their potential as biomarkers and therapeutic targets based on existing evidence are discussed. Owing to the recent advancements in protein targeting, the possibility of agents to modulate MCPs in cancer as therapeutic options are discussed.

SPARC enhances 5-FU chemosensitivity in gastric cancer by modulating epithelial-mesenchymal transition and apoptosis

Previous studies have shown that secreted protein acidic and rich in cysteine (SPARC) proteins can inhibit the development of cancer cells in various ways, such as by inhibiting angiogenesis and inhibiting cell proliferation. In fact, SPARC proteins may have an effect on the chemoresistance of gastric cancer cells to 5-Fluorouracil (5-FU), which needs further research in the future. Therefore, the purpose of this study was to explore the relationship between SPARC proteins and the chemosensitivity of gastric cancer cells to 5-FU. In vitro, after SPARC protein levels were regulated by plasmid, siRNA and human recombinant SPARC protein transfection in MGC-803, SGC-7901 and BGC-823 cells, we detected epithelial-mesenchymal transition (EMT), apoptosis markers and cell viability after 5-FU treatment. In vivo, we implanted BGC-823 cells with stable SPARC overexpression into nude mice. Tumour size was measured to assess the effect of SPARC protein on tumour formation and 5-FU chemosensitivity. In SGC-7901 and BGC-823 cells, both endogenous and exogenous upregulation of SPARC protein levels decreased cell viability, destroyed cytoskeletal F-actin, inhibited cell migration, and downregulated a series of transcription factors to inhibit cell EMT; it also upregulated cell apoptosis-related proteins to promote cell apoptosis. However, we obtained opposite results in SPARC knockdown MGC-803 cells. In vivo, compared with the control group, the group engrafted with BGC-823 cells stably overexpressing SPARC had a significant smaller tumour size. After 5-FU treatment, the new tumour gradually decreased in size. Our results show that the SPARC protein could enhance 5-FU chemosensitivity in gastric cancer cell lines by inhibiting EMT and promoting cell apoptosis.

SPARC regulates ferroptosis induced by sorafenib in human hepatocellular carcinoma

BACKGROUND

Secreted protein acidic and rich in cysteine (SPARC) is implicated in cancer progression, but its role and associated molecular mechanism in the sorafenib sensitivity of hepatocellular carcinoma cells (HCC) remains elusive.

METHODS

Human HCC cell lines Hep3B and HepG2 were treated with sorafenib alone or combined with activator or inhibitor of ferroptosis. Cell viability assay, reactive oxygen species (ROS) assay, lactate dehydrogenase (LDH) assay and western blot were used to study the regulatory mechanism of SPARC on HCC cells.

RESULTS

Overexpression of SPARC enhanced the cytotoxic effect of sorafenib in Hep3B and HepG2 cells compared with parental cells. Depletion of SPARC decreased the cytotoxic effect of sorafenib in Hep3B and HepG2 cells compared with parental cells. Moreover, overexpression of SPARC significantly induced LDH release, whereas depletion of SPARC suppressed the release of LDH in Hep3B and HepG2 cells. Inhibition of ferroptosis exerted a clear inhibitory role against LDH release, whereas activation of ferroptosis promoted the release of LDH in HCC cells, as accompanied with deregulated expression of ferroptosis-related proteins. Furthermore, overexpression of SPARC induced oxidative stress, whereas depletion of SPARC suppressed the production of ROS. Deferoxamine (DFX)-induced inhibition of ferroptosis suppressed the production of ROS, while activation of ferroptosis promoted the contents of ROS in HCC cells exposed to sorafenib.

CONCLUSION

Our findings give a better understanding of ferroptosis and its molecular mechanism in HCC cells that is regulated by SPARC in response to sorafenib.

Exercise-Induced Myokines can Explain the Importance of Physical Activity in the Elderly: An Overview

Physical activity has been found to aid the maintenance of health in the elderly. Exercise-induced skeletal muscle contractions lead to the production and secretion of many small proteins and proteoglycan peptides called myokines. Thus, studies on myokines are necessary for ensuring the maintenance of skeletal muscle health in the elderly. This review summarizes 13 myokines regulated by physical activity that are affected by aging and aims to understand their potential roles in metabolic diseases. We categorized myokines into two groups based on regulation by aerobic and anaerobic exercise. With aging, the secretion of apelin, β-aminoisobutyric acid (BAIBA), bone morphogenetic protein 7 (BMP-7), decorin, insulin-like growth factor 1 (IGF-1), interleukin-15 (IL-15), irisin, stromal cell-derived factor 1 (SDF-1), sestrin, secreted protein acidic rich in cysteine (SPARC), and vascular endothelial growth factor A (VEGF-A) decreased, while that of IL-6 and myostatin increased. Aerobic exercise upregulates apelin, BAIBA, IL-15, IL-6, irisin, SDF-1, sestrin, SPARC, and VEGF-A expression, while anaerobic exercise upregulates BMP-7, decorin, IGF-1, IL-15, IL-6, irisin, and VEGF-A expression. Myostatin is downregulated by both aerobic and anaerobic exercise. This review provides a rationale for developing exercise programs or interventions that maintain a balance between aerobic and anaerobic exercise in the elderly.

SPARC-p53: The double agents of cancer

Cancer is a complex disease with high incidence and mortality rates. The important role played by the tumor microenvironment in regulating oncogenesis, tumor growth, and metastasis is by now well accepted in the scientific community. SPARC is known to participate in tumor-stromal interactions and impact cancer growth in ambiguous ways, which either enhance or suppress cancer aggressiveness, in a context-dependent manner. p53 transcription factor, a well-established tumor suppressor, has been reported to promote tumor growth in certain situations, such as hypoxia, thus displaying a duality in its action. Although both proteins are being tested in clinical trials, the synergistic relation between them is yet to be explored in clinical practice. In this review, we address the controversial roles of SPARC and p53 as double agents in cancer, briefly summarizing the interaction found between these two molecules and its importance in cancer.

Proteomics analysis of the matrisome from MC38 experimental mouse liver metastases

Dissemination of primary tumors to distant anatomical sites has a substantial negative impact on patient prognosis. The liver is a common site for metastases from colorectal cancer, and patients with hepatic metastases have generally much shorter survival, raising a need to develop and implement novel strategies for targeting metastatic disease. The extracellular matrix (ECM) is a meshwork of highly crosslinked, insoluble high-molecular-mass proteins maintaining tissue integrity and establishing cell-cell interactions. Emerging evidence identifies the importance of the ECM in cancer cell migration, invasion, intravasation, and metastasis. Here, we isolated the ECM from MC38 mouse liver metastases using our optimized method of mild detergent solubilization followed by biochemical enrichment. The matrices were subjected to label-free quantitative mass spectrometry analysis, revealing proteins highly abundant in the metastatic matrisome. The resulting list of proteins upregulated in the ECM significantly predicted survival in patients with colorectal cancer but not other cancers with strong involvement of the ECM component. One of the proteins upregulated in liver metastatic ECM, annexin A1, was not previously studied in the context of cancer-associated matrisome. Here, we show that annexin A1 was markedly upregulated in colon cancer cell lines compared with cancer cells of other origin and also over-represented in human primary colorectal lesions, as well as hepatic metastases, compared with their adjacent healthy tissue counterparts. In conclusion, our study provides a comprehensive ECM characterization of MC38 experimental liver metastases and proposes annexin A1 as a putative target for this disease.NEW & NOTEWORTHY Here, the authors provide an extensive proteomics characterization of murine colorectal cancer liver metastasis matrisome (the ensemble of all extracellular matrix molecules). The findings presented in this study may enable identification of therapeutic targets or biomarkers of hepatic metastases.

Impact of Fibroblast-Derived SPARC on Invasiveness of Colorectal Cancer Cells

Secreted protein acidic and rich in cysteine (SPARC) is a matricellular protein modulating cell-matrix interactions and was found up-regulated in tumor stroma. To explore the effect of high stromal SPARC on colorectal cancer (CRC) cell behavior and clinical outcome, this study determined SPARC expression in patients suffering from stage II and III CRC using a publicly available mRNA data set and immunohistochemistry of tissue microarray sections. Moreover, in vitro co-culture models using CRC cell lines together with colon-associated fibroblasts were established to determine the effect of fibroblast-derived SPARC on cancer cells. In 466 patient samples, high SPARC mRNA was associated with a shorter disease-free survival. In 99 patients of the tissue microarray cohort, high stromal SPARC in the primary tumor was an independent predictor of shorter survival in patients with relapse (27 cases; HR = 4574, p = 0.004). In CRC cell lines, SPARC suppressed phosphorylation of focal adhesion kinase and stimulated cell migration. Colon-associated fibroblasts increased migration velocity by 30% and doubled track-length in SPARC-dependent manner. In a 3D co-culture system, fibroblast-derived SPARC enhanced tumor cell invasion. Taken together, stromal SPARC had a pro-metastatic impact in vitro and was a characteristic of aggressive tumors with poor prognosis in CRC patients.

Secreted protein acidic and rich in cysteine gene variants: Impact on susceptibility and survival of hepatocellular carcinoma patients

BACKGROUND AND AIM

Secreted protein acidic and rich in cysteine (SPARC) is a glycoprotein involved in extracellular matrix remodeling, which regulates cell growth. It could be involved in hepatic fibrogenesis related to chronic inflammations, hepatocellular carcinoma (HCC) angiogenesis, and tumor progression. We aimed to study the expressions of single nucleotide polymorphisms in the SPARC gene and their impact on susceptibility and survival of HCC patients.

METHODS

We conducted a case-control study on 200 HCC patients and 50 matched healthy controls. All patients were subjected to laboratory investigations, ultrasound, and real-time polymerase chain reaction to detect the genetic polymorphisms (rs3210714, rs11950384, and rs7719521) in the SPARC gene in the blood.

RESULTS

One hundred sixty (80%) patients were men with a mean age of 43 years. The SPARC gene showed a significant higher prevalence of rs3210714 mutation (i.e. AA or AG) and a significant lower prevalence of rs11950384 mutation (i.e. AA or AC) among HCC patients in comparison with controls (83% vs 22%, P ≤ 0.001) and (65.5 vs 86%, P = 0.005), respectively, while rs7719521 mutation did not reach significance. On univariate and multivariate analyses, elder age and having at least one copy of the mutant rs3210714 were associated with a significantly increased risk of HCC (P < 0.001 for both), whereas the presence of at least one copy of the mutant rs11950384 carried a significantly reduced risk of having HCC (P < 0.01). Overall survival did not differ significantly between any of the SPARC gene mutation groups.

CONCLUSIONS

The SPARC gene polymorphisms had a diverse impact on the susceptibility of HCC due to its ability to inhibit or promote tumor progression. SPARC gene polymorphisms were not related to survival of our HCC patients, and probably, this needs further analysis of other SPARC gene nucleotides.

The interaction between SPARC and GRP78 interferes with ER stress signaling and potentiates apoptosis via PERK/eIF2α and IRE1α/XBP-1 in colorectal cancer

Therapy-refractory disease is one of the main contributors of treatment failure in cancer. In colorectal cancer (CRC), SPARC can function as a sensitizer to conventional chemotherapy by enhancing apoptosis by interfering with the activity of Bcl-2. Here, we examine a novel mechanism by which SPARC further potentiates apoptosis via its modulation of the unfolded protein response (UPR). Using mass spectrometry to identify SPARC-associated proteins, GRP78 was identified as a protein partner for SPARC in CRC. In vitro studies conducted to assess the signaling events resulting from this interaction, included induction of ER stress with tunicamycin, 5-fluorouracil (5-FU), and irinotecan (CPT-11). We found that the interaction between GRP78 and SPARC increased during exposure to 5-FU, CPT-11, and tunicamycin, resulting in an attenuation of GRP78’s inhibition of apoptosis. In addition, we also show that SPARC can sensitize CRC cells to PERK/eIF2α and IRE1α/XBP-1 UPR signaling by interfering with ER stress following binding to GRP78, which leads to ER stress-associated cell death in CRC cells. In line with these findings, a lower expression of GRP78 relative to SPARC in CRC is associated with a lower IC₅₀ for 5-FU in either sensitive or therapy-refractory CRC cells. Interestingly, this observation correlates with tissue microarray analysis of 143 human CRC, where low GRP78 to SPARC expression level was prognostic of higher survival rate (P = 0.01) in individuals with CRC. This study demonstrates that modulation of UPR signaling by SPARC promotes ER stress-associated death and potentiates apoptosis. This may be an effective strategy that can be combined with current treatment options to improve therapeutic efficacy in CRC.

Gene expression profiling of triple-negative breast tumors with different expression of secreted protein acidic and cysteine rich (SPARC)

Aim: To determine the expression signature of triple-negative breast cancer (TNBC) with differences of secreted protein acidic and rich in cysteine expression and clinical behavior. Patients, materials & methods: cDNA microarray analysis was performed to determine the expression profiling of TNBC, characterized regarding secreted protein acidic and rich in cysteine expression status. Immunohistochemistry analysis on tissue microarrays containing an independent cohort of TNBC was performed for validation. Results: Negative staining of SOHLH2 and positive staining of DNAJC12 and LIM1 was correlated with a poor outcome of the patients. Conclusion: Our findings provide new information on transcriptome changes associated with the clinical behavior of TNBC that may serve as a potential tool for the identification and characterization of new candidate biomarkers.

Stabilin-1 is expressed in human breast cancer and supports tumor growth in mammary adenocarcinoma mouse model

Stabilin-1 is a multifunctional scavenger receptor expressed on alternatively-activated macrophages. Stabilin-1 mediates phagocytosis of "unwanted-self" components, intracellular sorting, and endocytic clearance of extracellular ligands including SPARC that modulates breast cancer growth. The expression of stabilin-1 was found on tumor-associated macrophages (TAM) in mouse and human cancers including melanoma, lymphoma, glioblastoma, and pancreatic insulinoma. Despite its tumor-promoting role in mouse models of melanoma and lymphoma the expression and functional role of stabilin-1 in breast cancer was unknown. Here, we demonstrate that stabilin-1 is expressed on TAM in human breast cancer, and its expression is most pronounced on stage I disease. Using stabilin-1 knockout (ko) mice we show that stabilin-1 facilitates growth of mouse TS/A mammary adenocarcinoma. Endocytosis assay on stabilin-1 ko TAM demonstrated impaired clearance of stabilin-1 ligands including SPARC that was capable of inducing cell death in TS/A cells. Affymetrix microarray analysis on purified TAM and reporter assays in stabilin-1 expressing cell lines demonstrated no influence of stabilin-1 expression on intracellular signalling. Our results suggest stabilin-1 mediated silent clearance of extracellular tumor growth-inhibiting factors (e.g. SPARC) as a mechanism of stabilin-1 induced tumor growth. Silent clearance function of stabilin-1 makes it an attractive candidate for delivery of immunomodulatory anti-cancer therapeutic drugs to TAM.

High secreted protein acidic and rich in cysteine expression in peritumoral fibroblasts predicts better prognosis in patients with resectable gastric cancer

Secreted protein acidic and rich in cysteine (SPARC) is an extracellular matrix glycoprotein that may serve an important role in epithelial-mesenchymal transition. Recent studies have demonstrated that SPARC status is a prognostic indicator in various cancer types; however, its value remains unclear in gastric cancer (GC). In the present study, the localization and prognostic impact of SPARC expression were evaluated in patients with GC. Immunohistochemical analysis of SPARC expression was performed in 117 surgically resected GC specimens, and the localization of SPARC positive cells, as well as the rassociation between SPARC expression and clinicopathological characteristics were evaluated. High SPARC expression was observed in 47 cases; the glycoprotein was localized in the peritumoral fibroblasts, but was rarely observed in the cytoplasm of cancer cells. Heterogeneity of SPARC expression was observed in 52 cases. High stromal SPARC expression was identified to be an independent predictor of more favorable prognosis (overall survival and recurrence free survival) in all patients (P<0.001). On subgroup analysis, this association remained significant in patients who received adjuvant chemotherapy, but not in patients who did not (P<0.001). Stromal SPARC expression predicts better prognosis in GC patients who underwent curative resection; this appears to be associated with improved response to chemotherapy.

Inhibition of Discoidin Domain Receptor 1 Reduces Collagen-mediated Tumorigenicity in Pancreatic Ductal Adenocarcinoma

The extracellular matrix (ECM), a principal component of pancreatic ductal adenocarcinoma (PDA), is rich in fibrillar collagens that facilitate tumor cell survival and chemoresistance. Discoidin domain receptor 1 (DDR1) is a receptor tyrosine kinase that specifically binds fibrillar collagens and has been implicated in promoting cell proliferation, migration, adhesion, ECM remodeling, and response to growth factors. We found that collagen-induced activation of DDR1 stimulated protumorigenic signaling through protein tyrosine kinase 2 (PYK2) and pseudopodium-enriched atypical kinase 1 (PEAK1) in pancreatic cancer cells. Pharmacologic inhibition of DDR1 with an ATP-competitive orally available small-molecule kinase inhibitor (7rh) abrogated collagen-induced DDR1 signaling in pancreatic tumor cells and consequently reduced colony formation and migration. Furthermore, the inhibition of DDR1 with 7rh showed striking efficacy in combination with chemotherapy in orthotopic xenografts and autochthonous pancreatic tumors where it significantly reduced DDR1 activation and downstream signaling, reduced primary tumor burden, and improved chemoresponse. These data demonstrate that targeting collagen signaling in conjunction with conventional cytotoxic chemotherapy has the potential to improve outcome for pancreatic cancer patients. Mol Cancer Ther; 16(11); 2473-85. ©2017 AACR.

Associations of tumor suppressor SPARCL1 with cancer progression and prognosis

SPARC-like protein 1 (SPARCL1), a member of the family of secreted proteins which is acidic and rich in cysteine, is a potential tumor suppressor gene in most types of tumor. A systemic review and bioinformatics analysis was carried out to determine the associations between SPARCL1 and tumor progression and clinical factors. Downregulation of SPARCL1, thought to be regulated by epigenetic modifications including DNA methylation, serves important functions in tumor progression and development, with its regulatory functions on cell viability, migration, invasion, cell adhesion and drug resistance. Downregulation of SPARCL1 was markedly associated with a poor overall survival rate of patients with one of ≥7 solid tumors and predicted increased mortality in patients with one of ≥4 distinct tumor types. The present review indicated that SPARCL1 may be a therapeutic target for cancer treatment and a biomarker to determine prognosis.

IL-32α-induced inflammation constitutes a link between obesity and colon cancer

Growing evidence indicates that adipose tissue inflammation is an important mechanism whereby obesity promotes cancer risk and progression. Since IL-32 is an important inflammatory and remodeling factor in obesity and is also related to colon cancer (CC) development, the aim of this study was to explore whether IL-32 could function as an inflammatory factor in human obesity-associated CC promoting a microenvironment favorable for tumor growth. Samples obtained from 84 subjects [27 lean (LN) and 57 obese (OB)] were used in the study. Enrolled subjects were further subclassified according to the established diagnostic protocol for CC (49 without CC and 35 with CC). We show, for the first time, that obesity (p = 0.009) and CC (p = 0.026) increase circulating concentrations of IL-32α. Consistently, we further showed that gene (p < 0.05) and protein (p < 0.01) expression levels of IL-32α were upregulated in VAT from obese patients with CC. Additionally, we revealed that IL32 expression levels are enhanced by hypoxia and inflammation-related factors in HT-29 CC cells as well as that IL-32α is involved in the upregulation of inflammation (IL8, TNF, and CCL2) and extracellular matrix (ECM) remodeling (SPP1 and MMP9) genes in HT-29 cancer cells. Additionally, we also demonstrate that the adipocyte-conditioned medium obtained from obese patients stimulates (p < 0.05) the expression of IL32 in human CC cells. These findings provide evidence of the potential involvement of IL-32 in the development of obesity-associated CC as a pro-inflammatory and ECM remodeling cytokine.

Pediatric Ependymoma: A Proteomics Perspective

BACKGROUND/AIM

Proteomics based on high-resolution mass spectrometry (MS) is the tool of choice for the analysis of protein presence, modifications and interactions, with increasing emphasis on the examination of tumor tissues. Application of MS-based proteomics offers a detailed picture of tumor tissue characteristics, facilitating the appreciation of different tumor entities, whilst providing reliable and fast results for therapeutic marker targeting and prognostic factor assessment. Through use of the high analytical resolution of nano-high-pressure liquid chromatography (nanoHPLC) and the high resolution of an Orbitrap Elite mass spectrometer, the present study aimed to provide knowledge on the proteome of the generally unknown entity of pediatric ependymal tumors.

MATERIALS AND METHODS

Ten resected specimens of childhood ependymoma were analyzed through a one-dimensional (1D) nanoLC-MS/MS approach. Method optimization steps were undertaken for both the sample preparation/protein extraction procedure and LC parameters, aiming to achieve the highest possible identification rates.

RESULTS

Following method optimization, each nanoLC-MS/MS run resulted in identification of more than 5,000 proteins and more than 25,000 peptides for every analyzed sample, thus detailing the greater part of the ependymoma proteome. Identified proteins were found to spread throughout all known tumor categories regarding their molecular function and subcellular localization.

CONCLUSION

Through the proposed nanoLC-MS/MS method herein we report, for the firs time, the ependymoma proteome database. A large number of similarities regarding proteome content are revealed compared to other two pediatric brain tumor entities; astrocytomas and medulloblastomas. Furthermore, through our approach, the majority of currently proposed markers for ependymoma (e.g. nucleolin, nestin, Ki67 and laminin subunit A2) as well as all major key players of the phosphoinositide 3-kinase pathway (seemingly implicated in ependymoma), were definitely detected.

Adaptive mechanisms of resistance to anti-neoplastic agents

Intrinsic and acquired resistance to conventional and targeted therapeutics is a fundamental reason for treatment failure in many cancer patients. Targeted approaches to overcome chemoresistance as well as resistance to targeted approaches require in depth understanding of the underlying molecular mechanisms. The anti-cancer activity of a drug can be limited by a broad variety of molecular events at different levels of drug action in a cell-autonomous and non-cell-autonomous manner. This review summarizes recent insights into the adaptive mechanisms used by tumours to resist therapy including cellular phenotypic plasticity, dynamic alterations of the tumour microenvironment, activation of redundant signal transduction pathways, modulation of drug target expression levels, and exploitation of pro-survival responses.

A phase I trial of azacitidine and nanoparticle albumin bound paclitaxel in patients with advanced or metastatic solid tumors

Background

Secreted protein acidic and rich in cysteine (SPARC), an albumin-binding protein, is downregulated by hypermethylation in many cancers. Hypomethylating agents such as azacitidine can upregulate SPARC in tumors, which may enhance the accumulation of albumin-bound drugs at tumor site. The objectives of this phase I trial was to determine the safety and maximum tolerated dose and to assess any clinical activity of the combination of azacytidine and weekly nanoparticle-albumin-bound (nab®) paclitaxel.

Methods

Patients received escalating azacytidine doses daily for 5 days, followed by nab-paclitaxel at the standard 100mg/m2 weekly dose for 3 weeks in 4-week cycles. Dose-limiting toxicities (DLTs) were monitored during the first cycle. Serum was obtained at baseline, during and after treatment for correlative study.

Results

All sixteen total patients enrolled were evaluable for toxicity, while 13 patients were evaluable for response. Two of five patients treated with 100mg/m2 of azacytidine had DLT of prolonged grade 4 neutropenia. Therefore, the MTD of azacitidine in this regimen is 75 mg/m². Three additional patients were treated with no grade 4 toxicity in cycle 1. Clinical activity included 1 complete response (CR) in refractory DLBCL, 2 CR in ovarian cancer, 4 partial responses (PR) in ovarian and endometrial cancer, 4 stable diseases (SD) in lung, sarcoma and pancreatic cancer, 1 unconfirmed PR in breast cancer, and 1 progression of disease in CLL/SLL.

Conclusions

Priming with azacitidine 75 mg/m² daily for 5 days, followed by weekly nab-paclitaxel 100 mg/m² weekly was well tolerated and results in dramatic responses pre-treated cancer patients.

Complete response to azacitidine priming and nab-paclitaxel in non-Hodgkin lymphoma resistant to biochemotherapy

The standard of care for first-line therapy in diffuse large B-cell lymphoma (DLBCL) is the rituximab, cyclophosphamide, doxorubicin, vincristine and prednisone (R-CHOP) regimen. For patients who fail to respond, have an incomplete response or relapse, numerous effective options exists besides salvage cisplatin-based regimen and autologous stem cell therapy. Even with this approach, the outcome remains very poor for this group of patients. The present case illustrates a 55-year-old woman diagnosed with DLBCL, who experienced an early incomplete response, later progression during treatment with the R-CHOP regimen. The patient received salvage therapy with rituximab, cisplatin and gemcitabine, again with an incomplete response. The patient declined consideration for stem cell therapy. Her disease progressed and she enrolled in the present phase I trial using azacitadine priming and nanoalbumin-bound (nab)-paclitaxel. After three cycles, follow-up positron emission tomography/computed tomography revealed a complete response for the first time since her initial diagnosis and the patient has remained disease-free for >6 years. Azacitadine and nab-paclitaxel combination appeared to be an effective regimen for the treatment of this patient with refractory DLBCL.

SPARC Regulates Transforming Growth Factor Beta Induced (TGFBI) Extracellular Matrix Deposition and Paclitaxel Response in Ovarian Cancer Cells

TGFBI has been shown to sensitize ovarian cancer cells to the cytotoxic effects of paclitaxel via an integrin receptor-mediated mechanism that modulates microtubule stability. Herein, we determine that TGFBI localizes within organized fibrillar structures in mesothelial-derived ECM. We determined that suppression of SPARC expression by shRNA decreased the deposition of TGFBI in mesothelial-derived ECM, without affecting its overall protein expression or secretion. Conversely, overexpression of SPARC increased TGFBI deposition. A SPARC-YFP fusion construct expressed by the Met5a cell line co-localized with TGFBI in the cell-derived ECM. Interestingly, in vitro produced SPARC was capable of precipitating TGFBI from cell lysates dependent on an intact SPARC carboxy-terminus with in vitro binding assays verifying a direct interaction. The last 37 amino acids of SPARC were shown to be required for the TGFBI interaction while expression of a SPARC-YFP construct lacking this region (aa 1-256) did not interact and co-localize with TGFBI in the ECM. Furthermore, ovarian cancer cells have a reduced motility and decreased response to the chemotherapeutic agent paclitaxel when plated on ECM derived from mesothelial cells lacking SPARC compared to control mesothelial-derived ECM. In conclusion, SPARC regulates the fibrillar ECM deposition of TGFBI through a novel interaction, subsequently influencing cancer cell behavior.

Secreted Protein Acidic and Rich in Cysteine (SPARC) Mediates Metastatic Dormancy of Prostate Cancer in Bone

Prostate cancer is known to frequently recur in bone; however, how dormant cells switch its phenotype leading to recurrent tumor remains poorly understood. We have isolated two syngeneic cell lines (indolent and aggressive) through in vivo selection by implanting PC3mm stem-like cells into tibial bones. We found that indolent cells retained the dormant phenotype, whereas aggressive cells grew rapidly in bone in vivo, and the growth rates of both cells in culture were similar, suggesting a role of the tumor microenvironment in the regulation of dormancy and recurrence. Indolent cells were found to secrete a high level of secreted protein acidic and rich in cysteine (SPARC), which significantly stimulated the expression of BMP7 in bone marrow stromal cells. The secreted BMP7 then kept cancer cells in a dormant state by inducing senescence, reducing "stemness," and activating dormancy-associated p38 MAPK signaling and p21 expression in cancer cells. Importantly, we found that SPARC was epigenetically silenced in aggressive cells by promoter methylation, but 5-azacytidine treatment reactivated the expression. Furthermore, high SPARC promoter methylation negatively correlated with disease-free survival of prostate cancer patients. We also found that the COX2 inhibitor NS398 down-regulated DNMTs and increased expression of SPARC, which led to tumor growth suppression in bone in vivo These findings suggest that SPARC plays a key role in maintaining the dormancy of prostate cancer cells in the bone microenvironment.

Peritumoral SPARC expression and patient outcome with resectable intrahepatic cholangiocarcinoma

Background and objectives

Cholangiocarcinoma (CCA) affects thousands worldwide with increasing incidence. SPARC (secreted protein acidic and rich in cysteine) plays an important role in cellular matrix interactions, wound repair, and cellular migration, and has been reported to prevent malignancy from growth. SPARC undergoes epigenetic silencing in pancreatic malignancy, but is frequently expressed by stromal fibroblasts adjacent to infiltrating pancreatic adenocarcinomas. CCA is also a desmoplastic tumor, similar to pancreatic adenocarcinoma. SPARC’s clinical influence on clinicopathological characteristics of mass-forming (MF)-CCA still remains unclear. In this study, we evaluate the expression of SPARC in tumor and stromal tissue to clarity its relation with prognosis.

Methods

Seventy-eight MF-CCA patients who underwent hepatectomy with curative intent were enrolled for an immunohistochemical study of SPARC. The expression of immunostaining of SPARC was characterized for both tumor and stromal tissues. We conducted survival analysis with 16 clinicopathological variables. The overall survival (OS) was analyzed by Kaplan–Meier analysis and Cox proportional hazards regression modeling.

Results

Thirty-three men and 45 women with MF-CCA were studied. Within total 78 subjects, 12 (15.4%) were classified as tumor negative/stroma negative, 37 (47.4%) as tumor positive/stroma negative, four (5.1%) as tumor negative/stroma positive, and 25 (32.1%) as tumor positive/stroma positive. With a median follow-up of 13.6 months, the 5-year OS was 14.9%. Cox proportional hazard analysis revealed that SPARC tumor positive and stromal negative immunostaining and curative hepatectomy predicted favorable OS in patients with MF-CCA after hepatectomy.

Conclusion

MF-CCA patients with SPARC tumor positive and stromal negative expression may have favorable OS rates after curative hepatectomy.

Establishment and characterization of models of chemotherapy resistance in colorectal cancer: Towards a predictive signature of chemoresistance

Current standard treatments for metastatic colorectal cancer (CRC) are based on combination regimens with one of the two chemotherapeutic drugs, irinotecan or oxaliplatin. However, drug resistance frequently limits the clinical efficacy of these therapies. In order to gain new insights into mechanisms associated with chemoresistance, and departing from three distinct CRC cell models, we generated a panel of human colorectal cancer cell lines with acquired resistance to either oxaliplatin or irinotecan. We characterized the resistant cell line variants with regards to their drug resistance profile and transcriptome, and matched our results with datasets generated from relevant clinical material to derive putative resistance biomarkers. We found that the chemoresistant cell line variants had distinctive irinotecan- or oxaliplatin-specific resistance profiles, with non-reciprocal cross-resistance. Furthermore, we could identify several new, as well as some previously described, drug resistance-associated genes for each resistant cell line variant. Each chemoresistant cell line variant acquired a unique set of changes that may represent distinct functional subtypes of chemotherapy resistance. In addition, and given the potential implications for selection of subsequent treatment, we also performed an exploratory analysis, in relevant patient cohorts, of the predictive value of each of the specific genes identified in our cellular models.

Proteomic studies of pediatric medulloblastoma tumors with 17p deletion

CNS tumors are the leading cause of cancer-related death in children. Medulloblastoma is the commonest pediatric CNS malignancy, wherein, despite multimodal therapy with surgery, radiation, and chemotherapy, 5 year survival rates merely approach 60%. Until present, gene expression and cytogenetic studies have produced contradicting findings regarding the molecular background of the specific disease. Through integration of genomics, bioinformatics, and proteomics, the current study aims to shed light at the proteomic-related molecular events responsible for MBL pathophysiology, as well as to provide molecular/protein/pathway answers concerning tumor-onset. Experiments were performed on tissues collected at surgery. With 17p loss being the commonest chromosomal aberrance observed in our sample set, array-CGH were employed to first distinguish for 17p-positive cases. 2-DE coupled to mass spectrometry identification exposed the MBL-specific protein profile. Protein profiles of malignant tissues were compared against profiles of normal cerebellar tissues, and quantitative protein differences were determined. Bioinformatics, functional and database analyses, characterization, and subnetwork profiling generated information on MBL protein interactions. Key molecules of the PI3K/mTOR signaling network were identified via the techniques applied herein. Among the findings IGF2, PI3K, Rictor, MAPKAP1, S6K1, 4EBP1, and ELF4A, as part of the IGF network (implicating PI3K/mTOR), were founded to be deregulated.

Stromal expression of SPARC in pancreatic adenocarcinoma

Pancreatic ductal adenocarcinoma (PDAC) stands as the poorest prognostic tumor of the digestive tract, with a 5-year survival rate of less than 5%. Therapeutic options for unresectable PDAC are extremely limited and there is a pressing need for expanded therapeutic approaches to improve current options available with gemcitabine-based regimens. With PDAC displaying one of the most prominent desmoplastic stromal reactions of all carcinomas, recent research has focused on the microenvironment surrounding PDAC cells. Secreted protein acid and rich in cysteine (SPARC), which is overexpressed in PDAC, may display tumor suppressor functions in several cancers (e.g., in colorectal, ovarian, prostate cancers, and acute myelogenous leukemia) but also appears to be overexpressed in other tumor types (e.g., breast cancer, melanoma, and glioblastoma). The apparent contradictory functions of SPARC may yield inhibition of angiogenesis via inhibition of vascular endothelial growth factor, while promoting epithelial-to-mesenchymal transition and invasion through matrix metalloprotease expression. This feature is of particular interest in PDAC where SPARC overexpression in the stroma stands along with inhibition of angiogenesis and promotion of cancer cell invasion and metastasis. Several therapeutic strategies to deplete stromal tissue have been developed. In this review, we focused on key preclinical and clinical data describing the role of SPARC in PDAC biology, the properties, and mechanisms of delivery of drugs that interact with SPARC and discuss the proof-of-concept clinical trials using nab-paclitaxel.

SIBLINGs and SPARC families: Their emerging roles in pancreatic cancer

Pancreatic cancer has a considerably poor prognosis with a 5-year survival probability of less than 5% when all stages are combined. Pancreatic cancer is characterized by its dense stroma, which is involved in the critical interplay with the tumor cells throughout tumor progression and furthermore, creates a barrier restricting efficient penetration of therapeutics. Alterations in a large number of genes are reflected by a limited number of signaling pathways, which are potential targets. Understanding more about the molecular basis of this devastating cancer type regarding tumor microenvironment, distinct subpopulations of cells, epithelial-to-mesenchymal transition and inflammation will lead to the development of various targeted therapies for controlling tumor growth and metastasis. In this complex scenario of pancreatic cancer, especially members of the “small integrin binding ligand N-linked glycoproteins” (SIBLINGs) and “secreted protein acidic and rich in cysteine” (SPARC) families have emerged due to their prominent roles in properties including proliferation, differentiation, apoptosis, adhesion, migration, angiogenesis, wound repair and regulation of extracellular matrix remodeling. SIBLINGs consist of five members, which include osteopontin (OPN), bone sialoprotein, dentin matrix protein 1, dentin sialophosphoprotein and matrix extracellular phosphoglycoprotein. The SPARC family of modular extracellular proteins is comprised of SPARC/osteonectin (ON) and SPARC-like 1 (hevin); secreted modular calcium binding proteins; testicans and follistatin-like protein. In this review, we especially focus on OPN and ON, elaborating on their special and growing importance in pancreatic cancer diagnosis and prognosis.

Role of SPARC in bone remodeling and cancer-related bone metastasis

There is a growing socioeconomic recognition that clinical bone diseases such as bone infections, bone tumors and osteoporotic bone loss mainly associated with ageing, are major issues in today's society. SPARC (secreted protein, acidic and rich in cysteine), a matricellular glycoprotein, may be a promising therapeutic target for preventing or treating bone-related diseases. In fact, SPARC is associated with tissue remodeling, repair, development, cell turnover, bone mineralization and may also participate in growth and progression of tumors, namely cancer-related bone metastasis. Yet, the function of SPARC in such biological processes is poorly understood and controversial. The main objective of this work is to review the current knowledge related to the activity of SPARC in bone remodeling, tumorigenesis, and bone metastasis. Progress in understanding SPARC biology may provide novel strategies for bone regeneration and the development of anti-angiogenic, anti-proliferative, or counter-adhesive treatments specifically against bone metastasis.

Prognostic impact of tumoral and/or peri-tumoral stromal SPARC expressions after surgery in patients with biliary tract cancer

BACKGROUND AND OBJECTIVE

SPARC (secreted protein acidic and rich in cysteine) is a matricellular glycoprotein that modulates interactions between tumoral cells and the peri-tumoralstroma. SPARC induces proliferation and invasion in vitro, and is a poor prognostic factor in several gastrointestinal cancers. Herein, we evaluated the prognostic value of tumoral and stromal SPARC expression in patients with biliary tract cancer (BTC) after surgery.

METHODS

We examined immunohistochemical patterns of SPARC expression in 110 resected BTC specimens and evaluated the prognostic value using prospectively collected data.

RESULTS

SPARC was expressed in tumoral cells in 46 samples (42%) and inperi-tumoralstromain 65 samples (59%). Tumoral SPARC expression was not related to major patient characteristics. Stromal SPARC expression was related to lymph node metastasis, stage, margin status, and tumor location. Overall survival at 5 years after surgery was 34.2%. Stromal SPARC (P < 0.001) and tumoral SPARC (P = 0.048) were associated with poor prognosis. Multivariate analysis revealed invasion into lymphatic system, residual tumor, and stromal SPARC as independent prognostic factors. The hazard ratio for patients with positive stromal SPARC was 3.20 (P < 0.001).

CONCLUSION

SPARC expression inperi-tumoralstroma predicts a poor prognosis for patients with BTC after surgery.

Myricetin enhance chemosensitivity of 5-fluorouracil on esophageal carcinoma in vitro and in vivo

BACKGROUND

Flavonoids are structurally heterogeneous, polyphenolic compounds present in high concentrations in fruits, vegetables, and other plant-derived foods. Currently, there is growing interest in the therapeutic applications of bioflavonoids for the treatment and prevention of diseases in humans. Myricetin is a naturally occurring flavonoid that is commonly found in tea, berries, fruits, vegetables, and medicinal herbs. Previous studies have shown that myricetin has antioxidant, anti-inflammatory and potent anticancer effects. It was interesting to investigate whether myricetin has the cooperative inhibitory effect combined with 5-fluorouracil on esophageal cancer cells.

METHODS

EC9706 cells were treated with 5-fluorouracil combination with or without myricetin. Colony formation assays, CCK-8 assay and flow cytometry were used to evaluate the chemosensitization activity of myricetin combine with 5-fluorouracil on the cell growth and viability, cell proliferation and apoptosis in vitro. Western blot was engaged to detect changes of Survivin, Cyclin D, Bcl-2, Caspase-3 and P53 protein expression level, which were associated with cells proliferation and apoptosis. Nude mouse tumor xenograft model was built to assessed chemosensitization effect of myricetin combine with 5-fluorouracil in vivo.

RESULTS

Compared with the 5-fluorouracil group without myricetin treatment, the groups treated with 5-fluorouracil combine with myricetin showed significantly suppressed cell survival fraction and proliferation, increased the cell apoptosis. Decreased Survivin, Cyclin D, Bcl-2, and increased Caspase-3, P53 expression level were aslo confirmed by western blot in 5-fluorouracil combine with myricetin groups in vitro. And in vivo assay, growth speed of tumor xenografts was significantly decreased in the mice treated with 5-fluorouracil + myricetin combiantion group.

CONCLUSIONS

The study demonstrated both in vitro and in vivo evidence that combination of myricetin with 5-fluorouracil chemotherapy can enhance tumor chemosensitivity of esophageal cancer EC9706 cells, and myricetin could be a potential chemosensitizer for esophageal cancer therapy.

Differential survival trends of stage II colorectal cancer patients relate to promoter methylation status of PCDH10, SPARC, and UCHL1

Surgical excision of colorectal cancer at early clinical stages is highly effective, but 20-30% of patients relapse. Therefore, it is of clinical relevance to identify patients at high risk for recurrence, who would benefit from adjuvant chemotherapy. The objective of this study was to identify prognostic and/or predictive methylation markers in stage II colorectal cancer patients. Therefore, we selected six gene promoters (FZD9, PCDH10 (protocadherin 10), SFRP2, SPARC (secreted protein acidic and rich in cysteine), UCHL1 (ubiquitin carboxyl-terminal hydrolase 1), and WIF1) for methylation analysis in formalin-fixed, paraffin-embedded primary tumor samples of colorectal cancer patients (n=143) who were enrolled in a prospective randomized phase III trial of the Austrian Breast and Colorectal cancer Study Group. Patients were randomized to adjuvant chemotherapy with 5-fluorouracil and leucovorin or surveillance only. Survival analyses revealed that combined evaluation of three promoters (PCDH10, SPARC, and UCHL1) showed differential effects with regard to disease-free survival and overall survival in the two treatment groups (significance level 0.007). In the chemotherapy arm, a statistically insignificant trend for patients without methylation toward longer survival was observed (P=0.069 for disease-free survival and P=0.139 for overall survival). Contrary, patients in the surveillance arm without methylation in their gene promoters had shorter disease-free survival and overall survival (P=0.031 for disease-free survival and P=0.003 for overall survival), indicating a prognostic effect of methylation in this group (test for interaction, P=0.006 for disease-free survival and P=0.018 for overall survival). These results indicate that promoter methylation status of PCDH10, SPARC, and UCHL1 may be used both as prognostic and predictive molecular marker for colorectal cancer patients and, therefore, may facilitate treatment decisions for stage II colorectal cancer.

Molecular mechanisms underlying the divergent roles of SPARC in human carcinogenesis

Communication between the cell and its surrounding environment, consisting of proteinaceous (non-living material) and extracellular matrix (ECM), is important for biophysiological and chemical signaling. This signaling results in a range of cellular activities, including cell division, adhesion, differentiation, invasion, migration and angiogenesis. The ECM non-structural secretory glycoprotein called secreted protein, acidic and rich in cysteine (SPARC), plays a significant role in altering cancer cell activity and the tumor's microenvironment (TME). However, the role of SPARC in cancer research has been the subject of controversy. This review mainly focuses on recent advances in understanding the contradictory nature of SPARC in relation to ECM assembly, cancer cell proliferation, adhesion, migration, apoptosis and tumor growth.

Genes related to suppression of malignant phenotype induced by Maitake D-Fraction in breast cancer cells

It is already known that the Maitake (D-Fraction) mushroom is involved in stimulating the immune system and activating certain cells that attack cancer, including macrophages, T-cells, and natural killer cells. According to the U.S. National Cancer Institute, polysaccharide complexes present in Maitake mushrooms appear to have significant anticancer activity. However, the exact molecular mechanism of the Maitake antitumoral effect is still unclear. Previously, we have reported that Maitake (D-Fraction) induces apoptosis in breast cancer cells by activation of BCL2-antagonist/killer 1 (BAK1) gene expression. At the present work, we are identifying which genes are responsible for the suppression of the tumoral phenotype mechanism induced by Maitake (D-Fraction) in breast cancer cells. Human breast cancer MCF-7 cells were treated with and without increased concentrations of Maitake D-Fraction (36, 91, 183, 367 μg/mL) for 24 h. Total RNA were isolated and cDNA microarrays were hybridized containing 25,000 human genes. Employing the cDNA microarray analysis, we found that Maitake D-Fraction modified the expression of 4068 genes (2420 were upmodulated and 1648 were downmodulated) in MCF-7 breast cancer cells in a dose-dependent manner during 24 h of treatment. The present data shows that Maitake D-Fraction suppresses the breast tumoral phenotype through a putative molecular mechanism modifying the expression of certain genes (such as IGFBP-7, ITGA2, ICAM3, SOD2, CAV-1, Cul-3, NRF2, Cycline E, ST7, and SPARC) that are involved in apoptosis stimulation, inhibition of cell growth and proliferation, cell cycle arrest, blocking migration and metastasis of tumoral cells, and inducing multidrug sensitivity. Altogether, these results suggest that Maitake D-Fraction could be a potential new target for breast cancer chemoprevention and treatment.

Nab-paclitaxel for breast cancer: a new formulation with an improved safety profile and greater efficacy

Taxanes, paclitaxel and docetaxel, are among the most effective agents used to treat breast cancer. Nab-paclitaxel (ABI-007, Abraxane) is paclitaxel encapsulated in albumin. This differs from the more conventional formulation which uses cremophor to increase the solubility of paclitaxel (CrEL-paclitaxel). In a randomized trial that formed the basis of its regulatory approval in the USA, 3-weekly nab-paclitaxel induced a higher response rate and longer time to progression than CrEL-paclitaxel in patients with metastatic breast cancer. Except for grade 3 sensory neuropathy, nab-paclitaxel was also safer. An interim analysis from a more recent randomized Phase II trial suggests that weekly nab-paclitaxel is more effective and safer than either 3-weekly nab-paclitaxel or 3-weekly docetaxel. The superior efficacy of nab-paclitaxel is presumably due to the improved safety profile, which allows for the administration of higher doses, a greater proportion of which actually reaches the tumor. Observations on the development of nab-paclitaxel have important implications for our understanding of dose response in the use of cytotoxic drugs to treat all forms of cancer. Although it is not yet clear whether nab-paclitaxel can be routinely substituted for CrEL-paclitaxel or docetaxel in breast cancer treatment regimens, it seems highly likely that this will occur within the next 5 years.

Epigenetics and colorectal cancer pathogenesis

Colorectal cancer (CRC) develops through a multistage process that results from the progressive accumulation of genetic mutations, and frequently as a result of mutations in the Wnt signaling pathway. However, it has become evident over the past two decades that epigenetic alterations of the chromatin, particularly the chromatin components in the promoter regions of tumor suppressors and oncogenes, play key roles in CRC pathogenesis. Epigenetic regulation is organized at multiple levels, involving primarily DNA methylation and selective histone modifications in cancer cells. Assessment of the CRC epigenome has revealed that virtually all CRCs have aberrantly methylated genes and that the average CRC methylome has thousands of abnormally methylated genes. Although relatively less is known about the patterns of specific histone modifications in CRC, selective histone modifications and resultant chromatin conformation have been shown to act, in concert with DNA methylation, to regulate gene expression to mediate CRC pathogenesis. Moreover, it is now clear that not only DNA methylation but also histone modifications are reversible processes. The increased understanding of epigenetic regulation of gene expression in the context of CRC pathogenesis has led to development of epigenetic biomarkers for CRC diagnosis and epigenetic drugs for CRC therapy.

Osteonectin Expression in Surrounding Stroma of Craniopharyngiomas

Craniopharyngioma is an epithelial tumor of the sellar region with a high survival rate but a high rate of recurrence, especially in children. Hypothalamic involvement, tumor recurrence, and multiple treatments result in clinical deterioration and impaired quality of life. Using immunohistochemistry, we investigated the expression pattern of osteonectin, a marker of tumor invasion and aggressive behavior, in 43 cases of craniopharyngioma. We observed a positive correlation of osteonectin expression in connective-type stromal tissue surrounding the epithelial tumor cells of craniopharyngioma with the extent of central nervous system infiltration and recurrence rate ( P < .001). Given the previous success of chemotherapeutic agents that target the tumor microenvironment, our findings on osteonectin expression in stroma of craniopharyngiomas might, hopefully, be a guide to find newer prognostic markers capable of estimating the risk of progression or recurrence. They may also aid in the development of therapeutics that target tumor microenvironment to improve patient outcome.

Nucleophosmin 1, upregulated in adenomas and cancers of the colon, inhibits p53-mediated cellular senescence

Dysregulation of nucleophosmin 1 (NPM1) has been found in numerous solid and hematological malignancies. Our previous meta-analysis of colorectal cancer (CRC) high throughput gene expression profiling studies identified it as a consistently reported up-regulated gene in the malignant state. Our aims were to compare NPM1 expression in normal colon, adenoma and CRC, to correlate their expressions with clinico-pathological parameters, and to assess the biological role of aberrant NPM1 expression in CRC cells. NPM1 transcript levels were studied in human CRC cell lines, whereas a tissue microarray of 57 normal human colon, 40 adenoma and 185 CRC samples were used to analyze NPM1 protein expression by immunohistochemistry. CRC cell lines were subjected to transient siRNA-mediated knockdown to study NPM1's roles on cell viability and senescence. NPM1 transcript levels were 7-11-folds higher in three different human CRC cell lines compared to normal colon cells. NPM1 protein expression was found to be progressively and significantly upregulated in CRC compared to adenomas and in adenomas compared to normal mucosa. Reducing NPM1 expression by siRNA had caused a significant decrease in cell viability, a concomitant increase in cellular senescence and cell cycle arrest. Cellular senescence induced under conditions of forced NPM1 suppression could be prevented by knocking down p53. The differential expression of NPM1 along the normal colon-adenoma-carcinoma progression and its involvement in resisting p53 related senescent growth arrest in CRC cell lines implicate its role in supporting CRC tumorigenesis.

Inhibition of COX-2 in colon cancer modulates tumor growth and MDR-1 expression to enhance tumor regression in therapy-refractory cancers in vivo

Higher cyclooxygenase 2 (COX-2) expression is often observed in aggressive colorectal cancers (CRCs). Here, we attempt to examine the association between COX-2 expression in therapy-refractory CRC, how it affects chemosensitivity, and whether, in primary tumors, it is predictive of clinical outcomes. Our results revealed higher COX-2 expression in chemoresistant CRC cells and tumor xenografts. In vitro, the combination of either aspirin or celecoxib with 5-fluorouracil (5-FU) was capable of improving chemosensitivity in chemorefractory CRC cells, but a synergistic effect with 5-FU could only be demonstrated with celecoxib. To examine the potential clinical significance of these observations, in vivo studies were undertaken, which also showed that the greatest tumor regression was achieved in chemoresistant xenografts after chemotherapy in combination with celecoxib, but not aspirin. We also noted that these chemoresistant tumors with higher COX-2 expression had a more aggressive growth rate. Given the dramatic response to a combination of celecoxib + 5-FU, the possibility that celecoxib may modulate chemosensitivity as a result of its ability to inhibit MDR-1 was examined. In addition, assessment of a tissue microarray consisting of 130 cases of CRCs revealed that, in humans, higher COX-2 expression was associated with poorer survival with a 68% increased risk of mortality, indicating that COX-2 expression is a marker of poor clinical outcome. The findings of this study point to a potential benefit of combining COX-2 inhibitors with current regimens to achieve better response in the treatment of therapy-refractory CRC and in using COX-2 expression as a prognostic marker to help identify individuals who would benefit the greatest from closer follow-up and more aggressive therapy.

Tumour-microenvironment interactions: role of tumour stroma and proteins produced by cancer-associated fibroblasts in chemotherapy response

BACKGROUND

Cytotoxic chemotherapy improves survival for some, but not all, cancer patients. Non-responders may experience unnecessary toxicity and cancer progression, thus creating an urgent need for biomarkers that can predict the response to chemotherapy. So far, the search for such biomarkers has primarily been focused on the cancer cells and less on their surrounding stroma. This stroma is known to act as a key regulator of tumour progression and, in addition, has been associated with drug delivery and drug efficacy. Fibroblasts represent the major cell type in cancer-associated stroma and they secrete extracellular matrix proteins as well as growth factors. This Medline-based literature review summarises the results from studies on epithelial cancers and aimed at investigating relationships between the quantity and quality of the intra-tumoral stroma, the cancer-associated fibroblasts, the proteins they produce and the concomitant response to chemotherapy. Biomarkers were selected for review that are known to affect cancer-related characteristics and patient prognosis.

RESULTS

The current literature supports the hypothesis that biomarkers derived from the tumour stroma may be useful to predict response to chemotherapy. This notion appears to be related to the overall quantity and cellularity of the intra-tumoural stroma and the predominant constituents of the extracellular matrix.

CONCLUSION

Increasing evidence is emerging showing that tumour-stroma interactions may not only affect tumour progression and patient prognosis, but also the response to chemotherapy. The tumour stroma-derived biomarkers that appear to be most appropriate to determine the patient's response to chemotherapy vary by tumour origin and the availability of pre-treatment tissue. For patients scheduled for adjuvant chemotherapy, the most promising biomarker appears to be the PLAU: SERPINE complex, whereas for patients scheduled for neo-adjuvant chemotherapy the tumour stroma quantity appears to be most relevant.

Progress in understanding role of SPARC protein in gastric cancer

SPARC is a cysteine-rich secretory protein that is highly conservative and shares >70% amino acid sequence homology across all kinds of living organisms. The single-copy gene encoding the SPARC protein is located on human chromosome 5q31.3-q32, consists of 10 exons, and has a full length of 25 900 bp. SPARC protein is mainly expressed in tissue repair-related fibroblasts and endothelial cells, and high expression of SPARC protein has been noted in some aggressive malignant tumors. The incidence and mortality of gastric cancer are high in China, and the high mortality is closely related with tumor invasion and metastasis. SPARC protein is abnormally expressed in gastric carcinoma, and there is still controversy over the role of SPARC in gastric carcinoma. In this paper we review recent progress in understanding the role of SPARC protein in gastric cancer.

Bioinformatic analysis of chemokine (C-C motif) ligand 21 and SPARC-like protein 1 revealing their associations with drug resistance in ovarian cancer

Chemokine (C-C motif) ligand 21 (CCL21) and SPARC-like protein 1 (SPARCL1/MAST9/hevin/SC-1) are associated with various biological behavior in the development of cancers. Although the expression of CCL21 and SPARCL1 is downregulated in many solid tumors, their roles in ovarian cancer and their associations with drug resistance have rarely been studied. We performed a comprehensive bioinformatic analysis consisting of motif analysis, literature co-occurrence, gene/protein-gene/protein interaction network, protein-small molecule interaction network, and microRNAs enrichments which revealed that CCL21 and SPARCL1 directly or indirectly interact with a number of genes, proteins, small molecules and pathways associated with drug resistance in ovarian and other cancers. These results suggested that CCL21 and SPARCL1 may contribute to drug resistance in ovarian cancer. This study provided important information for further investigation of drug resistance-related functions of CCL21 and SPARCL1 in ovarian cancer.

SPARC expression in CML is associated to imatinib treatment and to inhibition of leukemia cell proliferation

Background

SPARC is a matricellular glycoprotein with growth-inhibitory and antiangiogenic activity in some cell types. The study of this protein in hematopoietic malignancies led to conflicting reports about its role as a tumor suppressor or promoter, depending on its different functions in the tumor microenvironment. In this study we investigated the variations in SPARC production by peripheral blood cells from chronic myeloid leukemia (CML) patients at diagnosis and after treatment and we identified the subpopulation of cells that are the prevalent source of SPARC.

Methods

We evaluated SPARC expression using real-time PCR and western blotting. SPARC serum levels were detected by ELISA assay. Finally we analyzed the interaction between exogenous SPARC and imatinib (IM), in vitro, using ATP-lite and cell cycle analysis.

Results

Our study shows that the CML cells of patients at diagnosis have a low mRNA and protein expression of SPARC. Low serum levels of this protein are also recorded in CML patients at diagnosis. However, after IM treatment we observed an increase of SPARC mRNA, protein, and serum level in the peripheral blood of these patients that had already started at 3 months and was maintained for at least the 18 months of observation. This SPARC increase was predominantly due to monocyte production. In addition, exogenous SPARC protein reduced the growth of K562 cell line and synergized in vitro with IM by inhibiting cell cycle progression from G1 to S phase.

Conclusion

Our results suggest that low endogenous SPARC expression is a constant feature of BCR/ABL positive cells and that IM treatment induces SPARC overproduction by normal cells. This exogenous SPARC may inhibit CML cell proliferation and may synergize with IM activity against CML.