Differential proteomic analysis of human colorectal carcinoma cell lines metastasis-associated proteins

Lymph Node Metastasis in Gastrointestinal Carcinomas: A View from a Proteomics Perspective

Lymph node metastasis (LNM) is one of the major prognostic factors in human gastrointestinal carcinomas (GICs). The lymph node-positive patients have poorer survival than node-negative patients. LNM is directly associated with the recurrence and poor survival of patients with GICs. The early detection of LNM in patients and designing effective therapies to suppress LNM may significantly impact the survival of these patients. The rapid progress made in proteomic technologies could be successfully applied to identify molecular targets for cancers at high-throughput levels. LC-MS/MS analysis enables the identification of proteins involved in LN metastasis, which can be utilized for diagnostic and therapeutic applications. This review summarizes the studies on LN metastasis in GICs using proteomic approaches to date.

Clinical implications of heat shock protein 70 in oral carcinogenesis and prediction of progression and recurrence in oral squamous cell carcinoma patients: a retrospective clinicopathological study

BACKGROUND

Oral cancer is a common cause of death worldwide. The search for novel biomarkers for oral cancer is an ongoing struggle. Prognostic biomarkers are of great importance in diagnosis, and prediction of the cancer outcome. There are several disagreements in oral cancer studies over the role of heat shock proteins as prognostic markers. The current study investigated HSP70 expression in diverse tissues ranging from normal oral mucosa to dysplastic oral epithelium and oral squamous cell carcinoma to determine its role in oral carcinogenesis. Moreover, HSP70 was evaluated concerning different prognostic parameters to determine its capability in predicting cancer progression. Recurrence of tumor was recorded, and patients` disease-free survival was calculated and analyzed considering HSP70 expression to determine the potential utility of HSP70 immuno-expression in predicting recurrence.

METHODS

A retrospective study was accomplished on 50 cases of OSCC. Biopsies from the cancerous tissue, the free surgical margin, and the normal oral mucosa were used. The grading of dysplastic epithelium and OSCCs followed the criteria of WHO classification (2017). The clinicopathological and follow-up records for each patient were retrieved. Pearson's Chi-square test, one-way ANOVA, and post hoc tests were used to analyze the variance of HSP70 immuno-expression concerning different parameters. The Kaplan-Meier method was used to compute and visualize disease-free survival, and the log-rank test was used to analyze the data. With Cox regression, univariate and multivariate survival analyses were run. A P-value of 0.05 or less was regarded as statistically significant.

RESULTS

A significant increased expression of HSP70 was observed as the tissue progressed from normal to dysplastic epithelium, and carcinoma (P = 0.000). HSP70 revealed a significant increased expression by progression from mild to severe dysplasia (P = 0.023), and also from well to moderately and poorly differentiated carcinoma (P = 0.000). High HSP70 immuno-expression was significantly associated with progression of OSCC; large-sized tumors (P = 0.002), advanced TNM clinical stages (P = 0.001), positive nodal involvement (P = 0.001), presence of recurrence (P = .008), and reduced DFS (P = 0.014).

CONCLUSION

HSP70 has a crucial contribution to oral carcinogenesis, and its immune-expression could potentially be used as predictor of progression and recurrence of OSCC patients.

TRIAL REGISTRATION

Retrospectively registered.

CircRNA PGAM1 Promotes the Migration and Invasion of Pancreatic Adenocarcinoma Cells by Activating the AKT/mTOR Signaling Pathway

Pancreatic adenocarcinoma (PAAD) is a lethal malignancy of the gastrointestinal tract. Circular RNA, an endogenous noncoding RNA, is considered a new regulatory molecule in tumorigenesis and development. Here, we aimed to investigate the role of circPGAM1 in PAAD. The PAAD cell line HPAC was transfected with OE-circPGAM1 to overexpress circPGAM1 and treated with AZD5363 to inhibit the AKT/mTOR pathway. Simultaneously, another PAAD cell line BxPC-3 was transfected with sh-circPGAM1 to silence circPGAM1. The GEPIA database was used to determine the expression of circPGAM1 in PAAD and its association with overall and disease-free survival. CircPGAM1 expression levels were determined in cell lines using reverse transcription-quantitative PCR. The cell counting kit-8, wound healing, and transwell assays were performed to determine cell migration and invasion. The protein expression levels of phosphorylated AKT and mTOR were determined using western blotting. CircPGAM1 was overexpressed in PAAD and related to poor prognosis. Silencing circPGAM1 inhibited migration and invasion of BxPC-3 cells, and overexpression of circPGAM1 showed the opposite effects. Overall, circPGAM1 promoted the migration and invasion of PAAD cells through the AKT/mTOR axis.

Proteomic profiling and network biology of colorectal cancer liver metastasis

INTRODUCTION

Tissue-based proteomic studies of colorectal cancer (CRC) metastasis have delivered fragmented results, with very few therapeutic targets and prognostic biomarkers moving beyond the discovery phase. This situation is likely due to the difficulties in obtaining and analyzing large numbers of patient-derived metastatic samples, the own heterogeneity of CRC, and technical limitations in proteomics discovery. As an alternative, metastatic CRC cell lines provide a flexible framework to investigate the underlying mechanisms and network biology of metastasis for target discovery.

AREAS COVERED

In this perspective, we comment on different in-depth proteomic studies of metastatic versus non-metastatic CRC cell lines. Identified metastasis-related proteins are introduced and discussed according to the spatial location in different cellular fractions, with special emphasis on membrane/adhesion proteins, secreted proteins, and nuclear factors, including miRNAs associated with liver metastasis. Moreover, we analyze the biological significance and potential therapeutic applications of the identified liver metastasis-related proteins.

EXPERT OPINION

The combination of protein discovery and functional analysis is the only way to accelerate the progress to clinical translation of the proteomic-derived findings in a relatively fast pace. Patient-derived organoids represent a promising alternative to patient tissues and cell lines, but further optimizations are still required for achieving solid and reproducible results.

The role of heat shock proteins in metastatic colorectal cancer: A review

Heat shock proteins (HSPs) are a large molecular chaperone family classified by their molecular weights, including HSP27, HSP40, HSP60, HSP70, HSP90, and HSP110. HSPs are likely to have antiapoptotic properties and participate actively in various processes such as tumor cell proliferation, invasion, metastases, and death. In this review, we discuss comprehensively the functions of HSPs associated with the progression of colorectal cancer (CRC) and metastasis and resistance to cancer therapy. Taken together, HSPs have numerous clinical applications as biomarkers for cancer diagnosis and prognosis and potential therapeutic targets for CRC and its related metastases.

The Role of Heat Shock Protein 27 in Carcinogenesis and Treatment of Colorectal Cancer

The incidence of colorectal cancer (CRC) has significantly increased in recent decades, which has made this disease an important global health issue. Despite many efforts, there is no useful prognostic or diagnostic biomarker for CRC. Heat shock protein 27 (Hsp27) is one of the most studied members of the Hsp family. It has attracted particular attention in CRC pathogenesis since it is involved in fundamental cell functions for cell survival. Evidence shows that Hsp27 plays important role in CRC progression and metastasis. Hsp27 overexpression has been observed in CRC and is suggested to be associated with CRC's poor prognosis. In the present review, we focus on the current knowledge of the role of Hsp27 in CRC carcinogenesis and the underlying mechanisms. In addition, we discuss the value of targeting Hsp27 in CRC treatment.

The expression of ADAMTS14 is regulated by promoter DNA methylation and is associated with poor prognosis in colorectal cancer

Colorectal cancer (CRC) is one of the most common malignant tumors of digestive system, and its main cause of death is tumor metastasis. The occurrence of CRC is a polygenic and multi-step complex process involving genetic and epigenetic alterations. It has been demonstrated that ADAMTS14 (A disintegrin and metalloproteinase with thrombospondin motifs 14) was hypermethylated in esophageal cancer using whole-genome methylation microarray in our previous report. The present study revealed that ADAMTS14 was highly methylated accompanied with low expression in CRC. In addition, demethylation agent 5-Aza-dC could demethylate ADAMTS14 promoter region and reactivate ADAMTS14 expression effectively in vitro. Therefore, promoter hypermethylation was probably contributed to ADAMTS14 epigenetic silencing in CRC. Furthermore, ADAMTS14 protein expression was higher at invasive tumor front than at the tumor center or other areas of tumor. Kaplan-meier survival analysis indicated that the high ADAMTS14 expression was correlated with poor prognosis in CRC patients, suggesting the possibility that ADAMTS14 is a promising indicator in the evaluation of CRC prognosis.

Proteomics of Colorectal Cancer: Tumors, Organoids, and Cell Cultures-A Minireview

Proteomics, the study of the complete protein composition of a sample, is an important field for cancer research. Changes in the proteome can serve as a biomarker of cancer or lead to the development of a targeted therapy. This minireview will focus on mass spectrometry-based proteomics studies applied specifically to colorectal cancer, particularly the variety of cancer model systems used, including tumor samples, two-dimensional (2D) and three-dimensional (3D) cell cultures such as spheroids and organoids. A thorough discussion of the application of these systems will accompany the review of the literature, as each provides distinct advantages and disadvantages for colorectal cancer research. Finally, we provide conclusions and future perspectives for the application of these model systems to cancer research as a whole.

Mouse models of colorectal cancer: Past, present and future perspectives

Colorectal cancer (CRC) is the third most common diagnosed malignancy among both sexes in the United States as well as in the European Union. While the incidence and mortality rates in western, high developed countries are declining, reflecting the success of screening programs and improved treatment regimen, a rise of the overall global CRC burden can be observed due to lifestyle changes paralleling an increasing human development index. Despite a growing insight into the biology of CRC and many therapeutic improvements in the recent decades, preclinical in vivo models are still indispensable for the development of new treatment approaches. Since the development of carcinogen-induced rodent models for CRC more than 80 years ago, a plethora of animal models has been established to study colon cancer biology. Despite tenuous invasiveness and metastatic behavior, these models are useful for chemoprevention studies and to evaluate colitis-related carcinogenesis. Genetically engineered mouse models (GEMM) mirror the pathogenesis of sporadic as well as inherited CRC depending on the specific molecular pathways activated or inhibited. Although the vast majority of CRC GEMM lack invasiveness, metastasis and tumor heterogeneity, they still have proven useful for examination of the tumor microenvironment as well as systemic immune responses; thus, supporting development of new therapeutic avenues. Induction of metastatic disease by orthotopic injection of CRC cell lines is possible, but the so generated models lack genetic diversity and the number of suited cell lines is very limited. Patient-derived xenografts, in contrast, maintain the pathological and molecular characteristics of the individual patient’s CRC after subcutaneous implantation into immunodeficient mice and are therefore most reliable for preclinical drug development – even in comparison to GEMM or cell line-based analyses. However, subcutaneous patient-derived xenograft models are less suitable for studying most aspects of the tumor microenvironment and anti-tumoral immune responses. The authors review the distinct mouse models of CRC with an emphasis on their clinical relevance and shed light on the latest developments in the field of preclinical CRC models.

Increased expression of heat shock protein (HSP) 10 and HSP70 correlates with poor prognosis of nasopharyngeal carcinoma

BACKGROUND

Heat shock proteins (HSPs) are a large family of chaperones implicating in occurrence and progression of tumor. In our previous study, we found HSP10 correlates with poor prognosis of oral squamous cell carcinoma and astrocytoma. HSP70 is also an important part of this family and whether the alterations of HSP10 and HSP70 expression and their common expression correlates with carcinogenesis and progression of nasopharyngeal carcinoma (NPC) has not been reported.

METHOD

In this study, we investigate the correlation between the expression of HSP10 and HSP70 and clinicopathological characteristics in NPC by immunohistochemistry (IHC).

RESULTS

Results indicated that positive expression of HSP10 and HSP70 was higher in NPC tissues (both P<0.001). Positive expression of HSP10 and HSP70 proteins, and common positive expression of the two HSPs analyzed in advanced clinical stages were higher than that in early clinical stages (All P<0.05). There was significantly higher expression of HSP10, HSP70, and common expression in NPC with LNM (lymph node metastasis) compared with NPC without LNM (All P<0.05). Interestingly, positive expression of HSP10 and HSP70 proteins and common expression had an evidently inverse correlation with survival status (All P<0.05). Spearman's correlation analysis showed expression of HSP10 was positively associated with HSP70 (r=0.407, P<0 0.001). Kaplan-Meier analysis showed that the overall survival rates for NPC patients with positive expression of HSP10 and HSP70 and common expression were significantly lower than these patients with negative expression (All P<0.05). Furthermore, positive expression of HSP10 and HSP70 proteins was identified as independent poor prognostic factors for NPC patients (both P<0.05) by Cox regression analysis.

CONCLUSION

 In conclusion, HSP10 and HSP70 can serve as the poor prognostic factors for NPC patients.

ERp29 counteracts the suppression of malignancy mediated by endoplasmic reticulum stress and promotes the metastasis of colorectal cancer

Endoplasmic reticulum protein 29 (ERp29), an endoplasmic reticulum (ER) protein, participates in ER stress (ERS), but little is known about the association of ERp29 with ERS in the metastasis and prognosis of cancerous diseases. The present study revealed that ERp29 was important to ERS and interfered with the malignant behaviors of colorectal cancer (CRC). Experiments in in vitro and in animal models revealed that ERS inhibited the cell growth and suppressed the metastatic capacity of CRC cells, but ERp29 counteracted these effects. Furthermore, it was demonstrated that ERp29 recovered the migration and metastatic behaviors of CRC cells suppressed by ERS, mediated only when it combined with cullin5 (CUL5). ERp29 also relied on CUL5 to promote epithelial-mesenchymal transition. From the immunohistochemical examination of CRC tissues, the high expression of ERp29 was revealed to predict the poor prognosis of 457 CRC cases. The retrospective analysis of the clinicopathological data of patients with CRC was consistent with the results of the in vitro and in vivo experiments. Thus, ERp29 protected CRC cells from ERS-mediated reduction of malignancy to promote metastasis and may be a potential target of medical intervention for CRC therapy.

New HSP27 inhibitors efficiently suppress drug resistance development in cancer cells

Drug resistance is an important open problem in cancer treatment. In recent years, the heat shock protein HSP27 (HSPB1) was identified as a key player driving resistance development. HSP27 is overexpressed in many cancer types and influences cellular processes such as apoptosis, DNA repair, recombination, and formation of metastases. As a result cancer cells are able to suppress apoptosis and develop resistance to cytostatic drugs. To identify HSP27 inhibitors we follow a novel computational drug repositioning approach. We exploit a similarity between a predicted HSP27 binding site to a viral thymidine kinase to generate lead inhibitors for HSP27. Six of these leads were verified experimentally. They bind HSP27 and down-regulate its chaperone activity. Most importantly, all six compounds inhibit development of drug resistance in cellular assays. One of the leads – chlorpromazine – is an antipsychotic, which has a positive effect on survival time in human breast cancer. In summary, we make two important contributions: First, we put forward six novel leads, which inhibit HSP27 and tackle drug resistance. Second, we demonstrate the power of computational drug repositioning.

Key genes and regulatory networks involved in the initiation, progression and invasion of colorectal cancer

Aim

Until now, identification of drug targets for treatment of patients with specific stages of colorectal cancer (CRC) has remained a challenging field of research. Herein, we aimed to identify the key genes and regulatory networks involved in each stage of CRC.

Results

The results of gene expression profiles were integrated with protein-protein interaction networks, and topologically analyzed. The most important regulatory genes (e.g., CDK1, UBC, ESR1 and ATXN1) and signaling pathways (e.g., Wnt, MAPK and JAK-STAT) in CRC initiation, progression and metastasis were identified. In vitro analysis confirmed some in silico findings.

Conclusion

Our study introduces functional hub genes, subnetworks, prioritizes signaling pathways and novel biomarkers in CRC that may guide further development of targeted therapy programs.

Proteins are potent biomarkers to detect colon cancer progression

Colon cancer is the most common type of cancer and major cause of death worldwide. The detection of colon cancer is difficult in early stages. However, the secretory proteins have been used as ideal biomarker for the detection of colon cancer progress in cancer patients. Serum/tissue protein expression could help general practitioners to identify colon cancer at earlier stages. By this way, we use the biomarkers to evaluate the anticancer drugs and their response to therapy in cancer models. Recently, the biomarker discovery is important in cancer biology and disease management. Also, many measurable specific molecular components have been studied in colon cancer therapeutics. The biomolecules are mainly DNA, RNA, metabolites, enzymes, mRNA, aptamers and proteins. Thus, in this review we demonstrate the important protein biomarker in colon cancer development and molecular identification of protein biomarker discovery.

Quantitative patterns of Hsps in tubular adenoma compared with normal and tumor tissues reveal the value of Hsp10 and Hsp60 in early diagnosis of large bowel cancer

Large bowel carcinogenesis involves accumulation of genetic alterations leading to transformation of normal mucosa into dysplasia and, lastly, adenocarcinoma. It is pertinent to elucidate the molecular changes occurring in the pre-neoplastic lesions to facilitate early diagnosis and treatment. Heat shock proteins (Hsps), many of which are molecular chaperones, are implicated in carcinogenesis, and their variations with tumor progression encourage their study as biomarkers. There are many reports on Hsps and cancer but none to our knowledge on their systematic quantification in pre-neoplastic lesions of the large bowel. We performed immunohistochemical determinations of Hsp10, Hsp60, Hsp70, and Hsp90 in biopsies of large bowel tubular adenomas with moderate grade of dysplasia and compared to normal mucosa and adenocarcinoma with a moderate grade of differentiation (G2). A significant elevation of Hsp10 and Hsp60 only, i.e., in the absence of elevation of Hsp70 or Hsp90, in both epithelium and lamina propria was found in tubular adenoma by comparison with normal mucosa. In contrast, adenocarcinoma was characterized by the highest levels of Hsp10 and Hsp60 in epithelium and lamina propria, accompanied by the highest levels of Hsp70 only in epithelium and of Hsp90 only in lamina propria, by comparison with normal and tubular adenoma counterparts. Hsp10 and Hsp60 are promising biomarkers for early diagnosis of tubular adenoma and for its differentiation from more advanced malignant lesions. Hsp10 and Hsp60 may be implicated in carcinogenesis from its very early steps and, thus, are potentially convenient targets for therapy.

Fibersol-2 induces apoptosis of Apc-deficient colorectal Cancer (SW480) cells and decreases polyp formation in Apc MIN mice

The consumption of dietary fibers has been implicated with a lowered risk of human colorectal cancer. Proposed mechanisms involve alterations in the stool consistency, transit time, and formation of short-chain fatty acid by dietary fiber fermentation, and the reorganization of gut microbiota. Here we show that Fibersol-2, a digest-resistant maltodextrin, not only inhibits proliferation of colorectal SW480 cancer cell lines by increasing reactive oxygen species (ROS), but decreases the numbers of the adenoma count in Multiple Intestinal Neoplasia (MIN) mice carrying a mutation in the Adenomatous Polyposis Coli gene by 84 d of age. These observations provide direct evidence that Fibersol-2 intrinsically contains anti-cancer activity, independent of the intestinal metabolism and any potential interactions with the microbiota.

Primary tumor- and metastasis-derived colon cancer cells differently modulate connexin expression and function in human capillary endothelial cells

A gradual loss of functional gap junction between tumor cells has been reported with colorectal cancer (CRC) progression. Here, we explored if colon cancer cells could also affect gap junctions in blood capillary cells. Human microvascular endothelial cells (HMEC) were cultured with two CRC cell lines established from a unique patient. SW480 cells, derived from the primary tumor, migrate much faster across HMEC monolayer than SW620 cells derived from a metastatic site. The motile SW480 cells highly express and release HSP27 that increases gap junction formation with HMEC. Soluble HSP27 phosphorylates the connexin Cx43 on serine residues and induces its interaction with the oncoprotein 14-3-3, which promotes Cx43 delivery at the plasma membrane. The factors secreted by less motile SW620 cells do not affect Cx43 expression but up-regulate the expression of the connexin Cx32 through an activation of the chemokine receptor CXCR2. In turn, SW620 secreted factors induce tubulogenesis and ATP release. Altogether, cell lines derived from CRC primary tumor and metastasis differentially adapt endothelial cell functions by modulating connexin expression through released mediators.

Acetylcarnitine potentiates the anticarcinogenic effects of butyrate on SW480 colon cancer cells

Butyrate is a potent anticarcinogenic compound against colon cancer cells in vitro. However, its rapid metabolism is hypothesized to limit its anticancer benefits in colonic epithelial cells. Carnitine, a potent antioxidant, is essential to fatty acid oxidation. The aims of this study were to identify a colon cancer cell line capable of transporting carnitine. We evaluated the effect of carnitine and acetylcarnitine (ALCAR) on the response of colon carcinoma cells to butyrate. We explored the mechanisms underlying the anticarcinogenic benefit. SW480 cells were incubated with butyrate ± carnitine or ALCAR. Carnitine uptake was assessed using [3H]-carnitine. Apoptosis and cell viability were assessed using an ELISA kit and flow cytometry, respectively. Modulation of proteins implicated in carnitine transport, cell death and proliferation were assessed by western blotting. SW480 cells were found to transport carnitine primarily via the OCTN2 transporter. Butyrate induced SW480 cell death occurred at concentrations of 2 mM and higher. Cells treated with the combination of butyrate (3 mM) with ALCAR exhibited increased mortality. The addition of carnitine or ALCAR also increased butyrate-induced apoptosis. Butyrate increased levels of cyclin D1, p21 and PARP p86, but decreased Bcl-XL and survivin levels. Butyrate also downregulated dephospho-β-catenin and increased acetylated histone H4 levels. Butyrate and carnitine decreased survivin levels by ≥25%. ALCAR independently induced a 20% decrease in p21. These results demonstrate that butyrate and ALCAR are potentially beneficial anticarcinogenic nutrients that inhibit colon cancer cell survival in vitro. The combination of both agents may have superior anticarcinogenic properties than butyrate alone.

Unravelling the Complexity and Functions of MTA Coregulators in Human Cancer

Since the initial recognition of the metastasis-associated protein 1 (MTA1) as a metastasis-relevant gene approximately 20 years ago, our appreciation for the complex role of the MTA family of coregulatory proteins in human cancer has profoundly grown. MTA proteins consist of six family members with similar structural units and act as central signaling nodes for integrating upstream signals into regulatory chromatin-remodeling networks, leading to regulation of gene expression in cancer cells. Substantial experimental and clinical evidence demonstrates that MTA proteins, particularly MTA1, are frequently deregulated in a wide range of human cancers. The MTA family governs cell survival, the invasive and metastatic phenotypes of cancer cells, and the aggressiveness of cancer and the prognosis of patients with MTA1 overexpressing cancers. Our discussion here highlights our current understanding of the regulatory mechanisms and functional roles of MTA proteins in cancer progression and expands upon the potential implications of MTA proteins in cancer biology and cancer therapeutics.

Proteomics, genomics and transcriptomics: their emerging roles in the discovery and validation of colorectal cancer biomarkers

Colorectal cancer (CRC) is the second most common cancer in females and the third in males. Since CRC is often diagnosed at an advanced stage when prognosis is poor, identification of biomarkers for early diagnosis is urgently required. Recent advances in proteomics, genomics and transcriptomics have facilitated high-throughput profiling of data generated from CRC-related genes and proteins, providing a window of information for biomarker discovery and validation. However, transfer of candidate biomarkers from bench to bedside remains a dilemma. In this review, we will discuss emerging proteomic technologies and highlight various sample types utilized for proteomics-based identification of CRC biomarkers. Moreover, recent breakthroughs in genomics and transcriptomics for the identification of CRC biomarkers, with particular emphasis on the merits of emerging methylomic and miRNAomic strategies, will be discussed. Integration of proteomics, genomics and transcriptomics will facilitate the discovery and validation of CRC biomarkers leading to the emergence of personalized medicine.

Evaluation of ¹⁸F-FDG and ¹⁸F-FLT for monitoring therapeutic responses of colorectal cancer cells to radiotherapy

In order to compare the efficacy of (18)F-fluorothymidine (FLT) and (18)F-fluorodeoxyglucose (FDG) for monitoring early responses to irradiation, two human colorectal cancer (CRC) cell lines SW480 and SW620, which were derived from the primary lesions and the metastatic lymph node, underwent X-ray irradiation of 0, 10, or 20 Gy and were examined at 0, 24 and 72 h After irradiation, reduced proliferation of both SW480 and SW620 cells was observed in a dose-dependent manner (P<0.001), G0-G1 arrest was also noted in both cell types after 72 h in the 20 Gy group (P<0.001). Although increased apoptosis was observed in both cell lines after irradiation (P<0.001), a greater percentage of SW480 cells underwent apoptosis in response to irradiation than SW620 cells. Increased Hsp27 and decreased integrin β3, Ki67 and VEGFR2 expression was observed over time via immunocytochemistry and Western blot analysis (P<0.001), however, no significant changes were noted in response to irradiation. Finally, reduced uptake of (18)F-FLT by SW480 or SW620 cells was observed at 24-h post-irradiation, however, reduced (18)F-FDG uptake was only observed after 72 h. Therefore, we conclude that (18)F-FLT is a more suitable positron emission tomography (PET) tracer for monitoring early responses to irradiation in primary and metastatic lymph node CRC cells.

Comparative proteomics analysis of colorectal cancer

BACKGROUND AND OBJECTIVE

Protein expression in colon and rectal cancer (CRC) and paired normal tissues was examined by two-dimensional gel electrophoresis (2-DE) to identify differentially expressed proteins.

MATERIALS AND METHODS

Five fresh colorectal cancer and paired adjacent normal tissues were obtained and differentially expressed protein spots were determined using PDQuest software, with identification on the basis of MALDI- TOF mass spectra.

RESULTS

Compared with normal colorectal mucosa, protein abnormal expression of 65 spots varying more than 1.5 times were found in 2-DE gels from colorectal cancer samples (P<0.05); forty-two proteins were up-regulated and 23 were down-regulated; twelve protein spots were identified using mass spectrometry, of which 8 were up-regulated, including HSPB1 and Annexin A4, while 4 were down-regulated, the results being consistent with Western blot findings.

CONCLUSIONS

Two-dimensional electrophoresis reference maps for CRC tissues and adjacent normal mucosa (NMC) were established and 12 differentially expressed proteins were identified. Up-regulated HSPB1 and Annexin A4 may play many important roles in the pathogenesis of colorectal cancer.

Novel biomarkers for the prediction of metastasis in colorectal cancer

INTRODUCTION

In patients with metastatic colorectal cancers, multimodal management and the use of biological agents such as monoclonal antibodies have had major positive effects on survival. The ability to predict which patients may be at 'high risk' of distant metastasis could have major implications on patient management. Histomorphological, immunohistochemical or molecular biomarkers are currently being investigated in order to test their potential value as predictors of metastasis.

AREAS COVERED

Here, the author reviews the clinical and functional data supporting the investigation of three novel promising biomarkers for the prediction of metastasis in patients with colorectal cancer: tumor budding, Raf1 kinase inhibitor protein (RKIP) and metastasis-associated in colon cancer-1 (MACC1).

EXPERT OPINION

The lifespan of most potential biomarkers is short as evidenced by the rare cases that have successfully made their way into daily practice such as KRAS or microsatellite instability (MSI) status. Although the three biomarkers reviewed herein have the potential to become important predictive biomarkers of metastasis, they have similar hurdles to overcome before they can be implemented into clinical management: standardization and validation in prospective patient cohorts.

Improving colorectal cancer management: the potential of proteomics

Colorectal cancer (CRC) is the third most common cancer worldwide. Successful treatment is heavily dependent on tumor stage at the time of detection, but unfortunately CRC is often only detected in advanced stages. New biomarkers in the form of genes or proteins that can be used for diagnosis, prognostication, follow-up, and treatment selection and monitoring could be of great benefit for the management of CRC. Furthermore, proteins could prove valuable new targets for therapy. Therefore, clinical proteomics has gained a lot of scientific interest in this regard. To get an overall insight into the extent to which this research has contributed to a better management of CRC, we give a comprehensive overview of the results of proteomics research on CRC, focusing on expression proteomics, in other words, protein profiling studies. Furthermore, we evaluate the potential of the discriminating proteins identified in this research for clinical use as biomarkers for (early) diagnosis, prognosis and follow-up of CRC or as targets for new therapeutic regimens.

Comprehensive fluorogenic derivatization-liquid chromatography/tandem mass spectrometry proteomic analysis of colorectal cancer cell to identify biomarker candidate

Existing colorectal cancer biomarkers are insufficient for providing a quick and accurate diagnosis, which is critical for a good prognosis. More appropriate biomarkers are thus needed. To identify new colorectal cancer biomarker candidates, we conducted a comprehensive differential proteomic analysis of six cancer cell lines and a normal cell line, utilizing a fluorogenic derivatization-liquid chromatography-tandem mass spectrometry (FD-LC-MS/MS) approach. Two sets of intracellular biomarker candidates were identified: one for colorectal cancer, and the other for metastatic colorectal cancer. Our results suggest that cooperative expression of FABP5 and cyclophilin A might be linked to Her2 signaling. Upregulation of LDHB and downregulation of GAPDH suggest the existence of a specific nonglycolytic energy production pathway in metastatic colorectal cancer cells. Downregulation of 14-3-3ζ/δ, cystatin-B, Ran and thioredoxin could be a result of their secretion, which then stimulates metastasis via activity in the sera and ascitic fluids. We propose a possible flow scheme to describe the dynamics of protein expression in colorectal cancer cells leading to tumor progression and metastasis via cell proliferation, angiogenesis, disorganization of actin filaments and epithelial-mesenchymal transition. Our results suggest that colorectal tumor progression may be regulated by signaling mediated by Her2, hypoxia, and TGFβ.

HSP27 expression in primary colorectal cancers is dependent on mutation of KRAS and PI3K/AKT activation status and is independent of TP53

Colorectal adenomas display features of senescence, but these are often lost upon progression to carcinoma, indicating that oncogene induced senescence (OIS) could be a roadblock in colorectal cancer (CRC) development. Heat shock proteins (HSPs) have been implicated in the prognosis of CRC and HSP based therapy is a current interest for drug development. Recent cell culture studies have suggested that in the absence of a TP53 mutation, OIS mediated by PI3K/AKT activation can be circumvented by high expression of HSPs. Furthermore, while PI3K/AKT activation and KRAS mutations are independent inducers of OIS, PI3K/AKT activation can suppress KRAS-induced OIS when both are present in cultured cells. As KRAS mutations, PI3K/AKT activation and TP53 mutations are all common features of CRC, it is possible that the requirement for HSP to inhibit OIS in CRC is dependent on the mutation spectrum of a tumour. However, work on HSP that utilised mutation profiled human tumour tissues has been limited. Here, we characterised the expression of two major HSP proteins (HSP27 and 72) by immunohistochemistry (IHC), the mutation status of TP53, KRAS and PIK3CA genes by direct sequencing and the activation status of AKT by IHC in a cohort of unselected primary CRC (n=74). We compare our data with findings generated from cell-based studies. Expression of HSP27 and HSP72 was correlated to clinicopathological and survival data but no significant association was found. We also established the mutation status of TP53, KRAS and PIK3CA genes and the activation status of AKT in our CRC panel. We did not detect any associations between HSP27 or HSP72 expression with TP53 mutation status. However, HSP27 expression in CRCs was strongly associated with the co-presence of wildtype KRAS and activated PI3K/AKT (p=0.004), indicating a possible role of HSP27 in overcoming PI3K/AKT induced OIS in tumours. Our studies suggest a role for using archival tissues in validating hypotheses generated from cell culture based investigations.

Proteomic signatures of the desmoplastic invasion front reveal collagen type XII as a marker of myofibroblastic differentiation during colorectal cancer metastasis

Cancer-associated fibroblasts (CAFs), represent a pivotal compartment of solid cancers (desmoplasia), and are causatively implicated in cancer development and progression. CAFs are recruited by growth factors secreted by cancer cells and they present a myofibroblastic phenotype, similar to the one obtained by resident fibroblasts during wound healing. Paracrine signaling between cancer cells and CAFs results in a unique protein expression profile in areas of desmoplastic reaction, which is speculated to drive metastasis. In an attempt to decipher large-scale proteomic profiles of the cancer invasive margins, we developed an in vitro coculture model system, based on tumor-host cell interactions between colon cancer cells and CAFs. Proteomic analysis of conditioned media derived from these cocultures coupled to mass spectrometry and bioinformatic analysis was performed to uncover myofibroblastic signatures of the cancer invasion front. Our analysis resulted in the identification and generation of a desmoplastic protein dataset (DPD), consisting of 152 candidate proteins of desmoplasia. By using monoculture exclusion datasets, a secretome algorithm and gene-expression meta-analysis in DPD, we specified a 22-protein “myofibroblastic signature” with putative importance in the regulation of colorectal cancer metastasis. Of these proteins, we investigated collagen type XII by immunohistochemistry, a fibril-associated collagen with interrupted triple helices (FACIT), whose expression has not been reported in desmoplastic lesions in any type of cancer. Collagen type XII was highly expressed in desmoplastic stroma by and around alpha-smooth muscle actin (α-SMA) positive CAFs, as well as in cancer cells lining the invasion front, in a small cohort of colon cancer patients. Other stromal markers, such as collagen type III, were also expressed in stromal collagen, but not in cancer cells. In a complementary fashion, gene expression meta-analysis revealed that COL12A1 is also an upregulated gene in colorectal cancer. Our proteomic analysis identified previously documented markers of tumor invasion fronts and our DPD could serve as a pool for future investigation of the tumor microenvironment. Collagen type XII is a novel candidate marker of myofibroblasts, and/or cancer cells undergoing dedifferentiation.

Murine colon proteome and characterization of the protein pathways

Background

Most of the current proteomic researches focus on proteome alteration due to pathological disorders (i.e.: colorectal cancer) rather than normal healthy state when mentioning colon. As a result, there are lacks of information regarding normal whole tissue- colon proteome.

Results

We report here a detailed murine (mouse) whole tissue- colon protein reference dataset composed of 1237 confident protein (FDR < 2) with comprehensive insight on its peptide properties, cellular and subcellular localization, functional network GO annotation analysis, and its relative abundances. The presented dataset includes wide spectra of pI and Mw ranged from 3–12 and 4–600 KDa, respectively. Gravy index scoring predicted 19.5% membranous and 80.5% globularly located proteins. GO hierarchies and functional network analysis illustrated proteins function together with their relevance and implication of several candidates in malignancy such as Mitogen- activated protein kinase (Mapk8, 9) in colorectal cancer, Fibroblast growth factor receptor (Fgfr 2), Glutathione S-transferase (Gstp1) in prostate cancer, and Cell division control protein (Cdc42), Ras-related protein (Rac1,2) in pancreatic cancer. Protein abundances calculated with 3 different algorithms (NSAF, PAF and emPAI) provide a relative quantification under normal condition as guidance.

Conclusions

This highly confidence colon proteome catalogue will not only serve as a useful reference for further experiments characterizing differentially expressed proteins induced from diseased conditions, but also will aid in better understanding the ontology and functional absorptive mechanism of the colon as well.

Role of heat shock protein 27 in gemcitabine-resistant human pancreatic cancer: comparative proteomic analyses

The most notable obstacle hindering the effective treatment of human pancreatic cancer is intrinsic chemoresistance. In order to identify the candidate protein(s) responsible for the intrinsic chemoresistance, the protein expression profiling of human pancreatic adenocarcinoma cell line Capan-1 and its distinct surviving cells following primary treatment with gemcitabine (GEM) were compared by two-dimensional electrophoresis (2-DE) combined with liquid chromatography-mass spectrometry (LC-MS) or mass spectrometry (MS). In total, nine proteins were identified, and heat shock protein B1 (HSP27), one of the differentially expressed proteins, was selected for further validation. Furthermore, the results of western blotting and immunohistochemical staining indicated that HSP27 may be significant in pancreatic intrinsic chemoresistance to GEM. The findings of this study provide a platform for further elucidation of the underlying mechanisms of pancreatic cancer intrinsic chemoresistance and demonstrate that HSP27 may be a valid target for anticancer drug development.

Quantitative analysis of caveolin-rich lipid raft proteins from primary and metastatic colorectal cancer clones

Caveolin-rich lipid rafts (CLRs) are thickened sections of the cell membrane that are composed of the integral membrane proteins caveolins together with saturated long chain fatty acids, cholesterol and lipids. Membrane proteins - lipid raft proteins in particular - may play important roles in cell signaling and cell-cell interaction. Due to their unique structure, CLRs seem to be the preferred docking site for specific proteins involved in focal adhesion and cancer metastasis. Our objective was thus to identify and quantify CLR proteins from primary and metastatic colorectal cancer (CRC) clones. We found differential expression of nine CLR proteins from primary and metastatic CRC clones. Among the identified proteins, an immune system inhibiting protein was significantly overexpressed in the metastatic clone, while cell adhesion and transport molecules were among the overexpressed proteins in the primary clone. All the identified CRL proteins are involved in tumorigenesis, specifically metastasis, and may thus serve as therapeutic targets. A novel concept for identification and quantification of CLR proteins with label-free mass spectrometry method was specifically examined in this study. Validation of the method against immunoblotting and FACS analysis indicates that it can be applied for the identification of novel biomarkers for cancer and metastasis.

Proteomic analysis of colorectal cancer metastasis: stathmin-1 revealed as a player in cancer cell migration and prognostic marker

Metastasis accounts largely for the high mortality rate of colorectal cancer (CRC) patients. In this study, we performed comparative proteome analysis of primary CRC cell lines HCT-116 and its metastatic derivative E1 using 2-D DIGE. We identified 74 differentially expressed proteins, many of which function in transcription, translation, angiogenesis signal transduction, or cytoskeletal remodeling pathways, which are indispensable cellular processes involved in the metastatic cascade. Among these proteins, stathmin-1 (STMN1) was found to be highly up-regulated in E1 as compared to HCT-116 and was thus selected for further functional studies. Our results showed that perturbations in STMN1 levels resulted in significant changes in cell migration, invasion, adhesion, and colony formation. We further showed that the differential expression of STMN1 correlated with the cells' metastatic potential in other paradigms of CRC models. Using immunohistochemistry, we also showed that STMN1 was highly expressed in colorectal primary tumors and metastatic tissues as compared to the adjacent normal colorectal tissues. Furthermore, we also showed via tissue microarray analyses of 324 CRC tissues and Kaplan-Meier survival plot that CRC patients with higher expression of STMN1 have poorer prognosis.

Nuclear localization of 14-3-3epsilon inversely correlates with poor long-term survival of patients with colorectal cancer

BACKGROUND

14-3-3ε regulates diverse biological processes and plays a significant role in the formation of malignant tumors. However, the localization and clinical significance of 14-3-3ε in colorectal cancer (CRC) have not been elucidated.

METHODS

We investigated 14-3-3ε expression and its prognostic significance in CRC. CRC surgical samples were taken from 137 clinicopathologically characterized CRC cases. 14-3-3ε expression was tested by immunohistochemical assay. Separate Western blot of nuclear and cytosol preparations confirmed nuclear localization of 14-3-3ε protein.

RESULTS

Nuclear expression of 14-3-3ε was observed in 76.9% of normal colorectal tissue and 78.8% of all CRC samples. Statistical analysis showed that there was significant difference of nuclear 14-3-3ε expression in patients categorized according to lymph node metastasis. A trend was identified between decreasing nuclear 14-3-3ε expression in CRC and worsening clinical prognosis. Multivariate analysis showed that loss of nuclear 14-3-3ε expression was an independent prognostic indicator for patient's survival.

CONCLUSIONS

The current data provide evidence that 14-3-3ε is not exclusively a cytosolic protein, but is also detectable within the nucleus. Our results suggest that nuclear 14-3-3ε as a suppressor may serve as important biomarker of tumor metastasis. Loss of nuclear 14-3-3ε is closely associated with poor overall survival in CRC patients.

Proteomics identification of ITGB3 as a key regulator in reactive oxygen species-induced migration and invasion of colorectal cancer cells

Colorectal cancer (CRC) is the third most commonly diagnosed cancer in males and second in females worldwide. Unfortunately 40-50% of patients already have metastatic disease at presentation when prognosis is poor with a 5-year survival of <10%. Reactive oxygen species (ROS) have been proposed to play a crucial role in tumor metastasis. We now show that higher levels of ROS accumulation are found in a colorectal cancer-derived metastatic cell line (SW620) compared with a cell line (SW480) derived from the primary lesion from the same patient. In addition, ROS accumulation can affect both the migratory and invasive capacity of SW480 and SW620 cells. To explore the molecular mechanism underlying ROS-induced migration and invasion in CRC, we have compared protein expression patterns between SW480 and SW620 cells using a two-dimensional electrophoresis-based proteomics strategy. A total of 63 altered proteins were identified from tandem MS analysis. Cluster analysis revealed dysregulated expression of multiple redox regulative or ROS responsive proteins, implicating their functional roles in colorectal cancer metastasis. Molecular and pathological validation demonstrated that altered expression of PGAM1, GRB2, DJ-1, ITGB3, SOD-1, and STMN1 was closely correlated with the metastatic potential of CRC. Functional studies showed that ROS markedly up-regulated expression of ITGB3, which in turn promoted an aggressive phenotype in SW480 cells, with concomitant up-regulated expression of STMN1. In contrast, knockdown of ITGB3 expression could mitigate the migratory and invasive potential of SW620 or H(2)O(2)-treated SW480 cells, accompanied by down-regulated expression of STMN1. The function of ITGB3 was dependent on the surface expression of integrin αvβ3 heterodimer. Furthermore, STMN1 expression and the PI3K-Akt-mTOR pathway were found to be involved in ROS-induced and ITGB3-mediated migration and invasion of colorectal cancer cells. Taken together, these studies suggest that ITGB3 plays an important role in ROS-induced migration and invasion in CRC.

Identification of key players for colorectal cancer metastasis by iTRAQ quantitative proteomics profiling of isogenic SW480 and SW620 cell lines

This study compared the whole cell proteome profiles of two isogenic colorectal cancer (CRC) cell lines (primary SW480 cell line and its lymph node metastatic variant SW620), as an in vitro metastatic model, to gain an insight into the molecular events of CRC metastasis. Using iTRAQ (isobaric tags for relative and absolute quantitation) based shotgun proteomics approach, we identified 1140 unique proteins, out of which 147 were found to be significantly altered in the metastatic cell. Ingenuity pathway analysis with those significantly altered proteins, revealed cellular organization and assembly as the top-ranked altered biological function. Differential expression pattern of 6 candidate proteins were validated by Western blot. Among these, the low expression level of β-catenin combined with the up-regulation of CacyBP (Calcyclin binding Protein), a β-catenin degrading protein, in the metastatic cell provided a rational guide for the downstream functional assays. The relative expression pattern of these two proteins was further validated in three other CRC cells by Western blot and quantitative immunofluorescence studies. Overexpression of CacyBP in three different primary CRC cell lines showed significant reduction in adhesion characteristics as well as cellular β-catenin level as confirmed by our experiments, indicating the possible involvement of CacyBP in CRC metastasis. In short, this study demonstrates successful application of a quantitative proteomics approach to identify novel key players for CRC metastasis, which may serve as biomarkers and/or drug targets to improve CRC therapy.

RP101 (brivudine) binds to heat shock protein HSP27 (HSPB1) and enhances survival in animals and pancreatic cancer patients

BACKGROUND

Several reports describe the importance of the chaperone HSP27 (HSPB1) in cancer progression, and the demand for drugs that modulate HSPB1-activity is increasing rapidly. We reported earlier that RP101 (Bromovinyldeoxyuridine, BVDU, Brivudine) improves the efficacy of chemotherapy in pancreatic cancer.

METHODS

Chemistry: Binding of RP101 and HSPB1 was discovered by affinity chromatography. Molecular and cell biology: HSPB1 in vitro transcription/translation (TNT), Pull down using RP101-coupled magnetic beads, Immuno Co-precipitations, Structural modeling of HSP27 (HSPB1), Introduction of point mutations into linear expression templates by PCR, Heat shock, Tumor Invasion. Animal experiments: Treatment of AH13r Sarcomas in SD-rats. Clinical Studies with late-stage pancreatic cancer patients: Pilot study, Dose finding study, Phase II study (NCT00550004).

RESULTS

Here, we report that RP101 binds in vitro to the heat shock protein HSPB1 and inhibits interaction with its binding partners. As a result, more activated CASP9 was detected in RP101-treated cancer cells. We modeled HSPB1-structure and identified the RP101 binding site. When we tested RP101 as an anti-cancer drug in a rat model, we found that it improved chemotherapy. In clinical studies with late-stage pancreatic cancer patients, the dose of 500 mg/day was safe and efficient, but 760 mg/day turned out to be too high for lightweight patients.

CONCLUSIONS

The development of RP101 as a cancer drug represents a truly novel approach for prevention of chemoresistance and enhancement of chemosensitivity.

Monitoring early responses to irradiation with dual-tracer micro-PET in dual-tumor bearing mice

AIM: To monitor the early responses to irradiation in primary and metastatic colorectal cancer (CRC) with ¹⁸F-fluorothymidine (¹⁸F-FLT) and ¹⁸F-fluorodeoxyglucose (¹⁸F-FDG) small-animal position emission tomography (micro-PET).

METHODS: The primary and metastatic CRC cell lines, SW480 and SW620, were irradiated with 5, 10 and 20 Gy. After 24 h, the cell cycle phases were analyzed. A dual-tumor-bearing mouse model of primary and metastatic cancer was established by injecting SW480 and SW620 cells into mice. micro-PET with ¹⁸F-FLT and ¹⁸F-FDG was performed before and 24 h after irradiation with 5, 10 and 20 Gy. The region of interest (ROI) was drawn over the tumor and background to calculate the ratio of tumor to non-tumor (T/NT) in tissues. Immunohistochemical assay and Western blotting were used to examine the levels of integrin β_3, Ki-67, vascular endothelial growth factor receptor 2 (VEGFR2) and heat shock protein 27 (HSP27).

RESULTS: The proportion of SW480 and SW620 cells in the G₂-M phase was decreased with an increasing radiation dose. The proportion of SW480 cells in the G₀-G₁ phase was increased from 48.33% ± 4.55% to 87.09% ± 7.43% (P < 0.001) and that of SW620 cells in the S-phase was elevated from 43.57% ± 2.65% to 66.59% ± 7.37% (P = 0.021). In micro-PET study, with increasing dose of radiation, ¹⁸F-FLT uptake was significantly reduced from 3.65 ± 0.51 to 2.87 ± 0.47 (P = 0.008) in SW480 tumors and from 2.22 ± 0.42 to 1.76 ± 0.45 (P = 0.026) in SW620 tumors. ¹⁸F-FDG uptake in SW480 and SW620 tumors was reduced but not significantly (F = 0.582, P = 0.633 vs F = 0.273, P = 0.845). Dose of radiation was negatively correlated with ¹⁸F-FLT uptake in both SW480 and SW620 tumors (r = -0.727, P = 0.004; and r = -0.664, P = 0.009). No significant correlation was found between ¹⁸F-FDG uptake and radiation dose in SW480 or SW620 tumors. HSP27 and integrin β₃ expression was higher in SW480 than in SW620 tumors. The T/NT ratio for ¹⁸F-FLT uptake was positively correlated with HSP27 and integrin β₃ expression (r = 0.924, P = 0.004; and r = 0.813, P = 0.025).

CONCLUSION: ¹⁸F-FLT is more suitable than ¹⁸F-FDG in monitoring early responses to irradiation in both primary and metastatic lesions of colorectal cancer.

Serum proteome analysis for profiling protein markers associated with lymph node metastasis in colorectal carcinoma

Colorectal cancer (CRC) is the second leading cause of cancer death in the human population worldwide. In China, CRC ranks fifth among cancer deaths, with a continuous increase in the incidence. Most CRC patients have lymph node metastasis (LNM) when first diagnosed. Two-dimensional (2D) serum proteome analysis may be useful in discovering new biomarkers that may aid in the diagnosis and therapy of CRC patients. To determine the tumour metastasis-specific antigen markers of CRC metastasis, sera from 32 patients with non-LNM CRC and 40 patients with LNM CRC were selected for screening using 2D serum proteome analysis combined with mass spectrometry (MS). Pretreatment strategies, including sonication and depletion of albumin and immunoglobulin (Ig) G, were adopted for screening differentially expressed proteins of low abundance in serum. By 2D image analysis and Matrix-assisted laser desorption/ionisation-time of flight (MALDI-TOF)-MS identification, eight protein spots were differentially expressed and successfully identified. The molecule transthyretin (TTR) was further studied in these sera by enzyme-linked immunosorbent assay. TTR appears to be a potential CRC metastasis-specific serum biomarker, which may be of value in the clinical detection and management of CRC.

The discovery and validation of colorectal cancer biomarkers

Colorectal cancer is currently the third most common malignancy in the world. Patients have excellent prognosis following surgical resection if their tumour is still localized at diagnosis. By contrast, once the tumour has started to metastasize, prognosis is much poorer. Accurate early detection can therefore significantly reduce the mortality from this disease. However, current tests either lack the required sensitivity and selectivity or are costly and invasive. Improved biomarkers, or panels of biomarkers, are therefore urgently required. We have addressed current screening strategies and potential protein biomarkers that have been proposed. The role of both discovery and hypothesis-driven proteomics approaches for biomarker discovery and validation is discussed. Using such approaches we show how multiple reaction monitoring (MRM) can be successfully developed and used for quantitative multiplexed analysis of potential faecal biomarkers.

Expression of heat shock proteins in osteosarcomas

AIMS

Heat shock proteins (HSPs) protect cells against stress-associated injuries and are overexpressed in several malignant tumours. We investigated the potential roles of HSP27, HSP60, and HSP70 in conventional and low grade central osteosarcoma.

METHODS

Expressions of HSP27, HSP60, and HSP70 were analysed using immunohistochemistry on tissue sections from 52 cases of conventional osteosarcoma and 21 cases of low grade central osteosarcoma. We evaluated the expression of each protein and examined its relationship with clinicopathological parameters.

RESULTS

We found significantly different expressions of HSP27 and HSP70 between conventional and low grade central osteosarcoma [34.6% versus 4.8% (p = 0.008), 88.5% versus 14.3% (p < 0.001)]. However, HSP60 was highly expressed in both kinds of osteosarcoma (92.3% versus 85.7%). In conventional osteosarcoma, a higher expression of HSP27 was significantly related to distant metastasis (p = 0.034) and histological subtype [osteoblastic versus non-osteoblastic (p = 0.041)]. The expressions of HSP60 and HSP70 were not significantly related to any tested clinicopathological parameter.

CONCLUSIONS

HSP27 and HSP70 may be used as differential markers to distinguish conventional and low grade central osteosarcoma. HSP27 may be used as a possible prognostic marker in conventional osteosarcoma cases.

HSP70: a promising target for laryngeal carcinoma radiaotherapy by inhibiting cleavage and degradation of nucleolin

Previous studies have shown that heat shock proteins (HSPs) were upregulated in various types of tumors and were associated with histological grade, recurrence and metastasis of malignant tumors. In this study, we investigated whether heat shock protein 70 kDa (HSP70) was associated with histological grade of laryngeal squamous cell carcinomas (LSCC). We also determine the role of HSP70 in LSCC radiation resistance using a laryngeal carcinoma xenograft model by antisense HSP70 RNA technique. Immunohistochemistry data showed that HSP70 was detected in 96% of LSCC tissues (48 out of 50). The expression level of HSP70 was significantly lower in early stage of LSCC than that in late stage (P = 0.015). Radiation treatment result showed that the volumes and weights of implantation tumors in the group injected with antisense HSP70 oligos were significantly reduced comparing to the group injected with random oligos(p < 0.05). In addition, cleavage and degradation of tumor nucleolin in antisense HSP70 oligos injection group was significantly higher than that in random oligos injection group. Our result suggested that HSP70 may play a role in LSCC radiotherapy resistance by inhibiting cleavage and degradation of nucleolin.

Identification of serum biomarkers for colorectal cancer metastasis using a differential secretome approach

Lymph node metastasis is the major concern that causes death in colorectal cancers. However, biomarkers for cancer metastasis are still lacking. In this study, we applied an LC-MS/MS-based label-free quantitative proteomics approach to compare the differential secretome of a primary cell line SW480 and its lymph node metastatic cell line SW620 from the same colorectal cancer patient. We identified a total of 910 proteins from the conditioned media and 145 differential proteins between SW480 and SW620 (>1.5-fold change). The differential expression pattern of 6 candidate proteins was validated by Western blot analysis. Among them, trefoil factor 3 and growth/differentiation factor 15, two up-regulated proteins in SW620, were further analyzed in a large cohort of clinical tissue and serum samples. Sandwich ELISA assay showed that the serum levels of both proteins were significantly higher in lymph node metastatic colorectal cancers. Receiver operating characteristic curve analysis confirmed that serum trefoil factor 3 and growth/differentiation factor 15 could provide a discriminatory diagnostic test for predicting colorectal cancer metastasis. Immunohistochemical analysis also showed that the overexpression of trefoil factor 3 or growth/differentiation factor 15 in colorectal cancer was associated with lymph node metastatic behavior. This study showed an accurate, sensitive, and robust label-free quantitation approach for differential analysis of cancer secretome. The comparison of the cancer secretome in vitro is a feasible strategy to obtain valuable biomarkers for potential clinical application. Both trefoil factor 3 and growth/differentiation factor 15 could serve as potential biomarkers for the prediction of colorectal cancer metastasis.

Expression of HSP27, HSP72 and MRP proteins in in vitro co-culture of colon tumour cell spheroids with normal cells after incubation with rhTGF- beta1 and/or CPT-11

We studied the expression of inducible heat shock protein (HSP27, HSP72) and multidrug-resistance protein (MRP) in co-cultures of human colon carcinoma cell spheroids obtained from different grades of tumour with normal human colon epithelium, myofibroblast and endothelial cell monolayers. We also measured the influence of recombinant human transforming growth factor beta1 (rhTGF-beta1) and camptothecin (CPT-11), added as single agents or in combination, on the levels of the HSPs, MRP, interleukin (IL)-6 and nitric oxide (NO). An immunoblotting analysis with densitometry showed that rhTGF-beta1 and/or CPT-11 increased HSP27, HSP72 and MRP expression in tumour cells and myofibroblasts, as well as in co-cultures compared with appropriate controls. By contrast, in colonic epithelium, inhibition of HSPs and MRP was comparable with that of the control. In endothelial cells, HSP72 was undetectable. Direct interaction of colon tumour spheroids with normal myofibroblasts caused a significant, tumour-grade dependent increase in IL-6 production. Production of IL-6 was significantly lowered by rhTGF-beta1 and/or CPT-11. Tumour cell spheroids cultivated alone produced larger amounts of NO than normal cells. In co-culture, the level of the radical decreased compared with the sum of NO produced by the monocultures of the two types of cells. rhTGF-beta1 and/or CPT-11 decreased NO production both in tumour and normal cell monocultures and their co-cultures. In conclusion, direct interactions between tumour and normal cells influence the expression of HSP27, HSP72 and MRP, and alter IL-6 and NO production. rhTGF-beta1 and/or CPT-11 may potentate resistance to chemotherapy by increasing HSP and MRP expression but, on the other hand, they may limit tumour cell spread by decreasing the level of some soluble mediators of inflammation (IL-6 and NO).