SPARC and DNA methylation: Possible diagnostic and therapeutic implications in gastrointestinal cancers

Current data and future perspectives on DNA methylation in ovarian cancer (Review)

Ovarian cancer (OC) represents the most prevalent malignancy of the female reproductive system. Its distinguishing features include a high aggressiveness, substantial morbidity and mortality, and a lack of apparent symptoms, which collectively pose significant challenges for early detection. Given that aberrant DNA methylation events leading to altered gene expression are characteristic of numerous tumor types, there has been extensive research into epigenetic mechanisms, particularly DNA methylation, in human cancers. In the context of OC, DNA methylation is often associated with the regulation of critical genes, such as BRCA1/2 and Ras‑association domain family 1A. Methylation modifications within the promoter regions of these genes not only contribute to the pathogenesis of OC, but also induce medication resistance and influence the prognosis of patients with OC. As such, a more in‑depth understanding of DNA methylation underpinning carcinogenesis could potentially facilitate the development of more effective therapeutic approaches for this intricate disease. The present review focuses on classical tumor suppressor genes, oncogenes, signaling pathways and associated microRNAs in an aim to elucidate the influence of DNA methylation on the development and progression of OC. The advantages and limitations of employing DNA methylation in the diagnosis, treatment and prevention of OC are also discussed. On the whole, the present literature review indicates that the DNA methylation of specific genes could potentially serve as a prognostic biomarker for OC and a therapeutic target for personalized treatment strategies. Further investigations in this field may yield more efficacious diagnostic and therapeutic alternatives for patients with OC.

GP60 and SPARC as albumin receptors: key targeted sites for the delivery of antitumor drugs

Albumin is derived from human or animal blood, and its ability to bind to a large number of endogenous or exogenous biomolecules makes it an ideal drug carrier. As a result, albumin-based drug delivery systems are increasingly being studied. With these in mind, detailed studies of the transport mechanism of albumin-based drug carriers are particularly important. As albumin receptors, glycoprotein 60 (GP60) and secreted protein acidic and rich in cysteine (SPARC) play a crucial role in the delivery of albumin-based drug carriers. GP60 is expressed on vascular endothelial cells and enables albumin to cross the vascular endothelial cell layer, and SPARC is overexpressed in many types of tumor cells, while it is minimally expressed in normal tissue cells. Thus, this review supplements existing articles by detailing the research history and specific biological functions of GP60 or SPARC and research advances in the delivery of antitumor drugs using albumin as a carrier. Meanwhile, the deficiencies and future perspectives in the study of the interaction of albumin with GP60 and SPARC are also pointed out.

Hypermethylated ITGA8 Facilitate Bladder Cancer Cell Proliferation and Metastasis

DNA methylation plays a vital role during the development of tumorigenesis. The purpose of this study is to identify candidate DNA methylation drivers during progression of bladder cancer (BLCA). The methylation spectrum in bladder cancer tissues was detected by CHARM analysis, and methylated ITGA8 was selected for further study due to its low expression. Methylation levels in BLCA tissues and cells were detected with methylated-specific PCR (MSP), while mRNA expression and methylation of ITGA8 were detected by qRT-PCR and MSP. After treatment with 5-Aza-dC (DNA methylation inhibitor), the proliferation, migration, and invasion abilities of BLCA cells were determined by MTT, wound healing, and transwell assays, respectively. Flow cytometric analysis was performed to evaluate any variance in the cell cycle. In addition, the effect of demethylated ITGA8 on BLCA tumor growth was verified with an in vivo xenograft tumor model. Based on the methylation profiling of BLCA, ITGA8 was identified to be hypermethylated. ITGA8 methylation levels in BLCA tissues and cells were upregulated, and 5-Aza-dC significantly suppressed ITGA8 methylation levels and increased ITGA8 mRNA expression. Furthermore, after treatment with 5-Aza-dC, the propagation, migration, and invasiveness of the cancer cells were inhibited, and more cancer cells were arrested at the G0/G1 phase. In vivo assays further demonstrated that 5-Aza-dC could impede BLCA tumor growth by repressing methylation levels of ITGA8 and increasing ITGA8 mRNA expression. Hypermethylated ITGA8 facilitated BLCA progression, and 5-Aza-dC treatment inhibited BLCA cell propagation and metastasis by decreasing methylation levels of ITGA8 and inducing cell cycle arrest.

Nab-Paclitaxel in the Treatment of Gastrointestinal Cancers-Improvements in Clinical Efficacy and Safety

Taxanes (paclitaxel and docetaxel) are one of the most useful classes of anticancer drugs. Taxanes are highly hydrophobic; therefore, these drugs must be dissolved in organic solvents (polysorbate or Cremophor EL), which contribute to their toxicities. To reduce this toxicity and to enhance their efficacy, novel formulations have been developed. Nanoparticle albumin-bound paclitaxel (nab-paclitaxel) is an albumin-stabilized, Cremophor-free, and water-soluble nanoparticle formulation of paclitaxel. Nab-paclitaxel has better solubility and less infusion-associated toxicity compared to solvent-based paclitaxel. Additionally, nab-paclitaxel can be given at higher doses and concentrations compared with solvent-based paclitaxel. Based on its superior clinical efficacy and safety profile, nab-paclitaxel received FDA approval for metastatic breast cancer (2008) and NSCLC (2011). Among gastrointestinal cancers, it is now approved in the USA for treating patients with metastatic adenocarcinoma of the pancreas as first-line therapy in combination with gemcitabine. Furthermore, several clinical trials have suggested the potential efficacy of nab-paclitaxel as a single agent or in combination with other agents for the treatment of metastatic esophageal, gastric, bowel, and biliary tract cancers. Nab-paclitaxel has been demonstrated to have greater overall response rates (ORR) with enhanced progression-free survival (PFS), overall survival (OS) and a superior safety profile with fewer adverse effects in patients with gastrointestinal tract cancers. This review summarizes the advantages associated with nab-paclitaxel-based regimens in terms of improving clinical efficacy and the safety profile in upper gastrointestinal cancer.

Tetrahydrocurcumin Chemosensitizes Breast Cancer to Albumin-Bound Paclitaxel by Enhancing SPARC Expression through Demethylation

Paclitaxel is an effective chemotherapy drug for breast cancer (BC); however, drug resistance affects long-term clinical applications. In this study, we aimed to explore whether a natural compound, tetrahydrocurcumin (THC), could sensitize BC to albumin-bound paclitaxel (ab-PTX). The in vitro sensitization effect of THC to ab-PTX was evaluated in human BC cell lines, and in vivo chemosensitivity was measured using a xenograft BC tumor model. The expression of secreted protein acidic and rich in cysteine (SPARC), a speculated protein interacting with ab-PTX, was measured. Methylation-specific polymerase chain reaction (MSP) was used to further explore whether demethylation of SPARC by THC contributed to its chemosensitivity capabilities. Higher SPARC expression was correlated with a better prognosis in patients with BC. In vitro analysis showed THC enhanced the inhibitory effect of ab-PTX on BC cells and xenograft tumors and showed significant chemosensitivity. This enhancement mainly relied on upregulating the expression of SPARC through downregulating methylation of the SPARC gene. The demethylating agent, 5-Aza-2′-deoxycytidine (5-Aza-Cdr), decreased THC's chemosensitivity effect, further confirming this molecular mechanism. THC enhanced the inhibitory effect of ab-PTX in BC by downregulating methylation of the SPARC gene. Further, upregulated SPARC increased the efficacy of ab-PTX.

Design and experimental validation of OPERA_MET-A panel for deep methylation analysis by next generation sequencing

DNA methylation is the most recognized epigenetic mark that leads to a massive distortion in cancer cells. It has been observed that a large number of DNA aberrant methylation events occur simultaneously in a group of genes, thus providing a growth advantage to the cell in promoting cell differentiation and neoplastic transformation. Due to this reason, methylation profiles have been suggested as promising cancer biomarkers. Here, we designed and performed a first step of validation of a novel targeted next generation sequencing (NGS) panel for methylation analysis, which can simultaneously evaluate the methylation levels at CpG sites of multiple cancer-related genes. The OPERA_MET-A methylation panel was designed using the Ion AmpliSeq™ technology to amplify 155 regions with 125-175 bp mean length and covers a total of 1107 CpGs of 18 cancer-related genes. The performance of the panel was assessed by running commercially available fully methylated and unmethylated control human genomic DNA (gDNA) samples and a variable mixture of them. The libraries were run on Ion Torrent platform and the sequencing output was analyzed using the “methylation_analysis” plugin. DNA methylation calls on both Watson (W) and Crick (C) strands and methylated:unmethylated ratio for each CpG site were obtained. Cell lines, fresh frozen and formalin-fixed paraffin-embedded (FFPE) lung cancer tissues were tested. The OPERA_MET-A panel allows to run a minimum of 6 samples/530 chip to reach an observed mean target depth ≥2,500X (W and C strands) and an average number of mapped reads >750,000/sample. The conversion efficiency, determined by spiking-in unmethylated Lambda DNA into each sample before the bisulfite conversion process, was >97% for all samples. The observed percentage of global methylation for all CpGs was >95% and <5% for fully methylated and unmethylated gDNA samples, respectively, and the observed results for the variable mixtures were in agreement with what was expected. Methylation-specific NGS analysis represents a feasible method for a fast and multiplexed screening of cancer patients by a high-throughput approach. Moreover, it offers the opportunity to construct a more robust algorithm for disease prediction in cancer patients having a low quantity of biological material available.

Prognostic Significance of SPARC Expression in Breast Cancer: A Meta-Analysis and Bioinformatics Analysis

Secreted protein, acidic and rich in cysteine (SPARC, also known as osteonectin), is a small molecule glycoprotein associated with cell secretions. The purpose of our research is to clarify the clinicopathological and prognostic significance of SPARC expression in breast cancer. In this study, we performed a meta-analysis and bioinformatics analysis using the PubMed, Web of Science, Wanfang Data, and CNKI databases. The meta-analysis showed that SPARC expression was elevated in breast cancer tissue, compared with normal tissue, while SPARC expression in tumor stromal cells was higher than that of tumor cells. The expression of SPARC was positively correlated with histological grade and TNM staging. The Kaplan-Meier plotter showed that low SPARC expression was negatively correlated with the overall, postprogression, and distant metastasis survival rates of patients. According to Oncomine database, SPARC expression was upregulated in breast cancer than normal tissues. In TCGA database, univariate analysis showed that lymph node metastasis, distant metastasis, and TNM staging were negatively correlated with patient prognosis in breast cancers. Cox multivariate analysis showed that age, lymph node metastasis, distant metastasis, and TNM staging were important factors affecting the survival time of breast cancer patients. SPARC expression can be employed as a good indicator of prognosis of breast cancer patients, which will provide new methods and ideas of preventive treatment.

SPARC expression in desmoplastic and non desmoplastic pancreatic carcinoma and cholangiocarcinoma

BACKGROUND

The pancreatobiliary carcinomas are characterized by presence of desmoplastic stroma. Overexpression of secreted protein acid and rich in cysteine (SPARC), a matrix producing agent has been documented in pancreatic ductal adenocarcinomas, with survival benefits. This study was targeted to see if SPARC expression in pancreatobiliary carcinomas is responsible for stromal desmoplasia and its prognostic significance.

METHODS

In this retrospective study 48 cases of pancreatic cancer and 27 cases of cholangiocarcinoma were analyzed. The expression pattern of SPARC and vascular endothelial growth factor (VEGF) (angiogenic factors) was evaluated by immunohistochemistry on formalin fixed paraffin embedded tissues. Immunoreactivity was scored semi quantitatively based on stain intensity and stain distribution. SPARC expression was correlated with tumor histology, stromal desmoplasia, VEGF expression, various histological parameters and overall survival in patients. Real time polymerase chain reaction was performed in few cases to validate the immunohistochemistry expression pattern.

RESULTS

SPARC expression was high in peritumoral stroma in pancreatic carcinoma than in pancreatic controls; however, SPARC expression pattern was not grossly different in desmoplastic and non-desmoplastic pancreatobiliary carcinomas and in cholangiocarcinomas. No definite correlation was noted between SPARC expression and histological markers of severity and overall survival data.

CONCLUSIONS

The relevance of SPARC expression in pancreato-biliary carcinomas though may still be important for therapeutic decision making, it is not responsible for peritumoral stromal desmoplasia in these tumors and it does not have any significant prognostic implication.

SPARC: As a prognostic biomarker in rectal cancer patients treated with chemo-radiotherapy

BACKGROUND

The aim of this study is to search the prognostic value of SPARC expression in rectum cancer cases receiving postoperative radiotherapy.

METHODS

Forty three rectal cancer patients are recruited to this retrospective study. All patients received postoperative radiotherapy which the median dose was 5040 cGy and concomitant chemotherapy. Samples taken from their paraffin blocks were examined with immunohistochemical procedures.

RESULTS

When the association between SPARC expression and the clinicopathological feature was examined, there was a significant association between age and expression levels. Overall survival of patients with low expression was found to be 67 months whereas the overall survival of the patients with high expression was 32 months and the difference was statistically significant. Time to local recurrence of patients with low expression was found to be 74 months whereas time to local recurrence of the patients with high expression was 31 months. Progression free survival of the patients with low expression and high expression were 67 months and 32 months, respectively. In multivariate Cox regression analyses, high expression of SPARC was found to be associated with a statistically significant shorter overall survival and progression free survival.

CONCLUSIONS

High expression of SPARC is related to worse prognosis in rectal cancer patients.

The relationship between stromal cell derived SPARC in human gastric cancer tissue and its clinicopathologic significance

Background

We aimed to investigate the cellular source of secreted protein acidic and rich in cysteine (SPARC) in gastric cancer tissues and the relationship between SPARC expression and its prognostic significance.

Methods

The expression of SPARC in 365 primary advanced gastric adenocarcinomas and 39 non-cancerous tissues was evaluated by immunohistochemical staining. Double-immunofluorescence staining was used to reveal the cellular source of SPARC in tumor tissues. Western blotting and immunofluorescence staining were applied for verifying the endogenous expression of SPARC in human cell lines of gastric cancer and fibroblast.

Results

Higher positivity of SPARC was observed in gastric cancer tissues than non-cancerous gastric tissues (P=0.000). The positivity of SPARC was related to age (P=0.032), tumor location (P=0.018), depth of tumor invasion (P=0.011), nodal metastasis (P=0.023), TNM stage (P=0.034), the differentiation degree (P=0.006) and pathological type (P=0.002) of gastric cancer. SPARC in gastric cancer tissues was mainly expressed by cancer-associated fibroblasts. SPARC also appeared in neovascular endothelial cells and a few tumor-associated macrophages. The endogenous expression of SPARC in fibroblasts was suppressed by mucus-producing gastric adenocarcinoma cells(MKN-45). Increased SPARC expression in gastric cancer tissue was suggestive of a shorter cumulative survival in the patients with gastric adenocarcinoma, though this difference was not statistically significant(P>0.05).

Conclusion

SPARC in human gastric cancer tissue was derived from the stromal cells and was mainly produced by cancer-associated fibroblasts. Production of SPARC in fibroblasts was reduced by the mucus-producing gastric adenocarcinoma cells.

Epigenetic effects of inhibition of heat shock protein 90 (HSP90) in human pancreatic and colon cancer

Silencing of tumor suppressor and DNA repair genes through methylation plays a role in cancer development, growth and response to therapy in colorectal and pancreatic cancers. Heat shock protein 90 (HSP90) regulates transcription of DNA methyltransferase enzymes (DNMT). In addition, DNMTs are client proteins of HSP90. The aim of this study is to evaluate the effects of HSP90 inhibition on DNA methylation in colorectal and pancreatic cancer cell lines. Our data shows that inhibition of HSP90 using ganetespib resulted in downregulation of mRNA and protein expression of DNMT1, DNMT3A, and DNMT3B in HT-29 and MIA PaCa-2 cell lines. This in turn was associated with a drop in the fraction of methylated cytosine residues and re-expression of silenced genes including MLH-1, P16 and SPARC. These effects were validated in HT-29 tumors implanted subcutaneously in mice following in vivo administration of ganetespib. This work demonstrates the effectiveness of ganetespib, an HSP90 inhibitor in modulating DNA methylation through downregulation of DNMT expression.

Effect of Exposure to 900 MHz GSM Mobile Phone Radiofrequency Radiation on Estrogen Receptor Methylation Status in Colon Cells of Male Sprague Dawley Rats

BACKGROUND

Over the past several years, the rapidly increasing use of mobile phones has raised global concerns about the biological effects of exposure to radiofrequency (RF) radiation. Numerous studies have shown that exposure to electromagnetic fields (EMFs) can be associated with effects on the nervous, endocrine, immune, cardiovascular, hematopoietic and ocular systems. In spite of genetic diversity, the onset and progression of cancer can be controlled by epigenetic mechanisms such as gene promoter methylation. There are extensive studies on the epigenetic changes of the tumor suppressor genes as well as the identification of methylation biomarkers in colorectal cancer. Some studies have revealed that genetic changes can be induced by exposure to RF radiation. However, whether or not RF radiation is capable of inducing epigenetic alteration has not been clarified yet. To date, no study has been conducted on the effect of radiation on epigenetic alterations in colorectal cancer (CRC). Several studies have also shown that methylation of estrogen receptor α (ERα), MYOD, MGMT, SFRP2 and P16 play an important role in CRC. It can be hypothesized that RF exposure can be a reason for the high incidence of CRC in Iran. This study aimed to investigate whether epigenetic pattern of ERα is susceptible to RF radiation and if RF radiation can induce radioadaptive response as epigenetic changes after receiving the challenge dose (γ-ray).

MATERIAL AND METHOD

40 male Sprague-Dawley rats were divided into 4 equal groups (Group I: exposure to RF radiation of a GSM cell phone for 4 hours and sacrificed after 24 hours; Group II: RF exposure for 4 hours, exposure to Co-60 gamma radiation (3 Gy) after 24 hours and sacrificed after 72 hrs; Group III: only 3Gy gamma radiation; Group 4: control group). DNA from colon tissues was extracted to evaluate the methylation status by methylation specific PCR.

RESULTS

Our finding showed that exposure to GSM cell phone RF radiation was capable of altering the pattern of ERα gene methylation compared to that of non-exposed controls. Furthermore, no adaptive response phenomenon was induced in the pattern of ERα gene methylation after exposure to the challenging dose of Co-60 γ-rays.

CONCLUSION

It can be concluded that exposure to RF radiation emitted by GSM mobile phones can lead to epigenetic detrimental changes in ERα promoter methylation pattern.

Epigenetic regulation of HGF/Met receptor axis is critical for the outgrowth of bone metastasis from breast carcinoma

Our translational research deals with the influence of microenvironment on the phenotype and colonization of bone metastases from breast carcinoma, and on pre-metastatic niche formation. The aim of the present study was to clarify the origin of hepatocyte growth factor (HGF), ligand of Met receptor, the control of the axis HGF/Met by DNA methylation, and its importance for the nexus supportive cells-metastatic cells and for metastasis outgrowth. In bone metastasis of the 1833-xenograft model, DNA methyltransferase blockade using the chemotherapic drug 5-aza-2′-deoxycytidine (decitabine) strongly reduced the expression of HGF/Met receptor axis and of E-cadherin, with decrease of metastasis wideness and osteolysis, prolonging mice survival. Thus, DNA methylation events acted as commanders of breast carcinoma cells metastatizing to bone influencing the epithelial phenotype. HGF emerged as a bone-marrow stimulus, and the exosomes seemed to furnish HGF to metastatic cells. In fact, decitabine treatment similarly affected some markers of these microvesicles and HGF, indicating that its supply to recipient cells was prevented. Notably, in bone metastasis the hypomethylation of HGF, Met and E-cadherin promoters did not appear responsible for their elevated expression, but we suggest the involvement of hypermethylated regulators and of Wwox oncosuppressor, the latter being affected by decitabine. Wwox expression increased under decitabine strongly localizing in nuclei of bone metastases. We hypothesize a role of Wwox in Met activity since in vitro Wwox overexpression downregulated the level of nuclear-Met protein fragment and Met stability, also under long exposure of 1833 cells to decitabine. HGF enhanced phosphoMet and the activity in nuclei, an effect partially prevented by decitabine. Altogether, the data indicated the importance to target the tumor microenvironment by blocking epigenetic mechanisms, which control critical events for colonization such as HGF/Met axis and Wwox, as therapy of bone metastasis.

DNA Methylation Patterns in the Hypothalamus of Female Pubertal Goats

Female pubertal development is tightly controlled by complex mechanisms, including neuroendocrine and epigenetic regulatory pathways. Specific gene expression patterns can be influenced by DNA methylation changes in the hypothalamus, which can in turn regulate timing of puberty onset. In order to understand the relationship between DNA methylation changes and gene expression patterns in the hypothalamus of pubertal goats, whole-genome bisulfite sequencing and RNA-sequencing analyses were carried out. There was a decline in DNA methylation levels in the hypothalamus during puberty and 268 differentially methylated regions (DMR) in the genome, with differential patterns in different gene regions. There were 1049 genes identified with distinct expression patterns. High levels of DNA methylation were detected in promoters, introns and 3′-untranslated regions (UTRs). Levels of methylation decreased gradually from promoters to 5′-UTRs and increased from 5′-UTRs to introns. Methylation density analysis demonstrated that methylation level variation was consistent with the density in the promoter, exon, intron, 5′-UTRs and 3′-UTRs. Analyses of CpG island (CGI) sites showed that the enriched gene contents were gene bodies, intergenic regions and introns, and these CGI sites were hypermethylated. Our study demonstrated that DNA methylation changes may influence gene expression profiles in the hypothalamus of goats during the onset of puberty, which may provide new insights into the mechanisms involved in pubertal onset.

Methylation status at HYAL2 predicts overall and progression-free survival of colon cancer patients under 5-FU chemotherapy

DNA methylation variations in gene promoter regions are well documented tumor-specific alterations in human malignancies including colon cancer, which may influence tumor behavior and clinical outcome. As a subset of colon cancer patients does not benefit from adjuvant chemotherapy, predictive biomarkers are desirable. Here, we describe that DNA methylation levels at CpG loci of hyaluronoglucosaminidase 2 (HYLA2) could be used to identify stage II and III colon cancer patients who are most likely to benefit from 5-flourouracil (5-FU) chemotherapy with respect to overall survival and progression-free survival.

Coordinate regulation of microenvironmental stimuli and role of methylation in bone metastasis from breast carcinoma

The pathogenesis of bone metastasis is unclear, and much focus in metastatic biology and therapy relays on epigenetic alterations. Since DNA-methyltransferase blockade with 5-aza-2'-deoxycytidine (dAza) counteracts tumour growth, here we utilized dAza to clarify whether molecular events undergoing epigenetic control were critical for bone metastatization. In particular, we investigated the patterns of secreted-protein acidic and rich in cysteine (SPARC) and of Endothelin 1, affected by DNA methyltransferases in tumours, with the hypothesis that in bone metastasis a coordinate function of SPARC and Endothelin 1, if any occurs, was orchestrated by DNA methylation. To this purpose, we prepared a xenograft model with the clone 1833, derived from human-MDA-MB231 cells, and dAza administration slowed-down metastasis outgrowth. This seemed consequent to the reductions of SPARC and Endothelin 1 at invasive front and in the bone marrow, mostly due to loss of Twist. In the metastasis bulk Snail, partly reduced by dAza, might sustain Endothelin 1-SPARC cooperativity. Both SPARC and Endothelin 1 underwent post-translational control by miRNAs, a molecular mechanism that might explain the in vivo data. Ectopic miR29a reduced SPARC expression also under long-term dAza exposure, while Endothelin 1 down-regulation occurred in the presence of endogenous-miR98 expression. Notably, dAza effects differed depending on in vivo and in vitro conditions. In 1833 cells exposed to 30-days dAza, SPARC-protein level was practically unaffected, while Endothelin 1 induction depended on the 3'-UTR functionality. The blockade of methyltransferases leading to SPARC reduction in vivo, might represent a promising strategy to hamper early steps of the metastatic process affecting the osteogenic niche.

Different epigenetic states define syncytiotrophoblast and cytotrophoblast nuclei in the trophoblast of the human placenta

INTRODUCTION

The syncytiotrophoblast (STB) epithelial covering of the villous tree in the human placenta is a multi-nucleated syncytium that is sustained by continuous incorporation of differentiating cytotrophoblast (CTB) cells. STB nuclei display a variety of morphologies, but are generally more condensed in comparison to CTB nuclei. Here, we consider whether this condensation is a feature of epigenetic regulation of chromatin structure.

METHODS

Semi-quantitative immunohistochemical investigations of a panel of histone modifications were performed to determine the relative proportions in CTB and STB nuclear populations. We also investigated the patterns of DNA methylation and distribution of DNA methyltransferases enzymes in these populations.

RESULTS

Unexpectedly DNA methylation, and H3K9me3 and H3K27me3, which are modifications associated with heterochromatin, are present at lower levels in STB nuclei compared to CTB, despite the intensive condensation in the former nuclear population and the progenitor state of the latter. By contrast, STB nuclei are enriched for H4K20me3, which is also associated with repressive states. 5'hydroxymethylcytosine immunoreactivity is higher in STB, with intense staining observed in the highly condensed nuclei within syncytial knots.

DISCUSSION

Cell-type specific epigenetic states exist within the trophoblast populations potentially regulating their different functions and developmental properties and suggesting non-canonical epigenetic states associated with the properties of these cells.

Nanoparticle formulation of ormeloxifene for pancreatic cancer

Pancreatic cancer is the fourth most prevalent cancer with about an 85% mortality rate; thus, an utmost need exists to discover new therapeutic modalities that would enhance therapy outcomes of this disease with minimal or no side effects. Ormeloxifene (ORM), a synthetic molecule, has exhibited potent anti-cancer effects through inhibition of important oncogenic and proliferation signaling pathways. However, the anti-cancer efficacy of ORM can be further improved by developing its nanoformulation, which will also offer tumor specific targeted delivery. Therefore, we have developed a novel ORM encapsulated poly(lactic-co-glycolic acid) nanoparticle (NP) formulation (PLGA-ORM NP). This formulation was characterized for particle size, chemical composition, and drug loading efficiency, using various physico-chemical methods (TEM, FT-IR, DSC, TGA, and HPLC). Because of its facile composition, this novel formulation is compatible with antibody/aptamer conjugation to achieve tumor specific targeting. The particle size analysis of this PLGA-ORM formulation (∼100 nm) indicates that this formulation can preferentially reach and accumulate in tumors by the Enhanced Permeability and Retention (EPR) effect. Cellular uptake and internalization studies demonstrate that PLGA-ORM NPs escape lysosomal degradation, providing efficient endosomal release to cytosol. PLGA-ORM NPs showed remarkable anti-cancer potential in various pancreatic cancer cells (HPAF-II, AsPC-1, BxPC-3, Panc-1, and MiaPaca) and a BxPC-3 xenograft mice model resulting in increased animal survival. PLGA-ORM NPs suppressed pancreatic tumor growth via suppression of Akt phosphorylation and expression of MUC1, HER2, PCNA, CK19 and CD31. This study suggests that the PLGA-ORM formulation is highly efficient for the inhibition of pancreatic tumor growth and thus can be valuable for the treatment of pancreatic cancer in the future.

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.

SPARC expression is negatively correlated with clinicopathological factors of gastric cancer and inhibits malignancy of gastric cancer cells

Secreted protein acidic and rich in cysteine (SPARC) is a glycoprotein which plays multiple roles in different types of cancer. Our previous study showed that SPARC overexpression inhibited the growth and angiogenesis of tumors, and reduced expression of vascular endothelial growth factor (VEGF). However, the relationship between SPARC expression and clinicopathological factors of gastric cancer (GC) is controversial, and the role of SPARC in GC remains unclear. We evaluated expression of SPARC in 65 human GC tissues using immunohistochemistry (IHC). The results indicated that SPARC expression was negatively correlated with clinicopathological factors of GC. In vitro assay showed that SPARC overexpression decreased proliferation and clonogenicity by suppressing CD44 expression. In addition, SPARC overexpression inhibited VEGF induced proliferation and arrested cell cycle of GC cells by reducing the activation of VEGFR2, ERK1/2 and AKT signaling pathways. SPARC suppressed the invasion and migration of GC by reducing MMP-7, MMP-9, N-cadherin, Sp1 and p-ERK1/2 expression. In the in vivo assay, cancer metastasis mouse models were established by tail vein injection. The results revealed that the lung metastases of SPARC-overexpressing GC cells in the mice were much fewer than those of control cells.

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.

Transport properties of pancreatic cancer describe gemcitabine delivery and response

BACKGROUND

The therapeutic resistance of pancreatic ductal adenocarcinoma (PDAC) is partly ascribed to ineffective delivery of chemotherapy to cancer cells. We hypothesized that physical properties at vascular, extracellular, and cellular scales influence delivery of and response to gemcitabine-based therapy.

METHODS

We developed a method to measure mass transport properties during routine contrast-enhanced CT scans of individual human PDAC tumors. Additionally, we evaluated gemcitabine infusion during PDAC resection in 12 patients, measuring gemcitabine incorporation into tumor DNA and correlating its uptake with human equilibrative nucleoside transporter (hENT1) levels, stromal reaction, and CT-derived mass transport properties. We also studied associations between CT-derived transport properties and clinical outcomes in patients who received preoperative gemcitabine-based chemoradiotherapy for resectable PDAC.

RESULTS

Transport modeling of 176 CT scans illustrated striking differences in transport properties between normal pancreas and tumor, with a wide array of enhancement profiles. Reflecting the interpatient differences in contrast enhancement, resected tumors exhibited dramatic differences in gemcitabine DNA incorporation, despite similar intravascular pharmacokinetics. Gemcitabine incorporation into tumor DNA was inversely related to CT-derived transport parameters and PDAC stromal score, after accounting for hENT1 levels. Moreover, stromal score directly correlated with CT-derived parameters. Among 110 patients who received preoperative gemcitabine-based chemoradiotherapy, CT-derived parameters correlated with pathological response and survival.

CONCLUSION

Gemcitabine incorporation into tumor DNA is highly variable and correlates with multiscale transport properties that can be derived from routine CT scans. Furthermore, pretherapy CT-derived properties correlate with clinically relevant endpoints.

TRIAL REGISTRATION

Clinicaltrials.gov NCT01276613.

FUNDING

Lustgarten Foundation (989161), Department of Defense (W81XWH-09-1-0212), NIH (U54CA151668, KCA088084).

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.