Cartilage oligomeric matrix protein (COMP) promotes cell proliferation in early-onset colon cancer tumorigenesis.

BACKGROUND: Colon cancer (CC) is the third most commonly diagnosed cancer in the USA. While the overall incidence is declining, it is rising alarmingly in young patients (EOCC). CC in young patients tends to be more aggressive and often diagnosed at more advanced stages and portend poorer prognosis. Our recently published data showed that EOCC is a distinct disease with unique molecular features compared to late-onset CC (LOCC). The Cartilage Oligomeric Matrix Protein (COMP) was shown to be significantly upregulated in EOCC and correlated with poor survival. However, the role of COMP in CC tumorigenesis, especially in young patients, is not well understood. Thus, the aim of this study was to elucidate the role of COMP in CC tumorigenesis by modulating COMP levels in vitro and test how it affects proliferation. Then, patient samples were evaluated by testing the levels of proliferation marker Ki67. In addition, this study investigates whether higher transcriptional mRNA levels of COMP seen in more aggressive early-onset CC correlate with protein levels compared to late-onset CC. METHODS: COMP mRNA levels in fresh frozen colon tumors (young: n = 5; old: n = 5) were assessed by quantitative PCR (qPCR). Additionally, CC cell lines were profiled for COMP expression to choose an in vitro model to study the role of COMP in CC tumorigenesis. HT-29 (low COMP expression) and CaCo-2 (high COMP expression) cells were used for in vitro proliferation studies. Immunohistochemical (IHC) analysis was conducted to assess COMP and Ki67 protein levels in formalin-fixed paraffin-embedded (FFPE) colon tumors. RESULTS: Significantly higher COMP expression levels were observed in fresh frozen EOCC compared to LOCC tumors. This observation confirmed our previously reported results from NanoString gene expression assay using FFPE samples. Cell proliferation was significantly increased in HT-29 and CaCo-2 cells upon treatment with human recombinant COMP protein after 48 and 72 h (P < 0.05). This increase was more profound in HT-29 cells. Staining for COMP and Ki67 revealed high COMP protein levels in EOCC compared to LOCC patients. CONCLUSION: COMP mRNA and protein levels are significantly higher in EOCC patients. Higher COMP levels correlate with increased proliferation suggesting a role in CC tumorigenesis.

Thrombospondins Differentially Regulate Proteins Involved in Arterial Remodeling.

Thrombospondins (TSPs) are matricellular glycoproteins expressed in response to vascular injury. TSP-1 and TSP-2 are promotors of arterial remodeling while TSP-5 is believed to be protective. The current study assessed the differential effect of TSPs on protein expression in vascular smooth muscle cells (VSMCs). We hypothesized that TSP-1, TSP-2 and TSP-5 would regulate VSMC proteins involved in arterial remodeling. Human VSMCs were exposed to TSP-1, -2, -5 or serum free media (24 hours). Cell lysates were used to assess the targets TSP-1, TSP-2, TSP-5 and CD44), while the culture media was used to detect TGF-ß1, PDGF-BB, ANGPTL-4 and IL-8. Statistical analysis was performed by t-test and p< 0.05 was considered significant. All TSPs increased their own expression and TSP-5 increased TSP-2. TSP-1 and TSP-2 increased production of ANGPTL-4 and PDGF-BB, while TSP-5 only increased ANGPTL-4. TSP-1 increased exclusively TGF-ß1 and CD44 production. TSP-2 increased TSP-1 expression. All TSPs decreased IL-8. The findings suggest that TSP-1 and TSP-2 may promote vascular remodeling, in part, by increasing ANGPTL-4, PDGF-BB and their own expression. TSP-5 did not upregulate the inflammatory mediators TSP-1, PDGF-BB or TGF-ß1, but upregulated its own expression, which could be a protective mechanism against the response to vascular injury.

Increasing Incidence of Colon Cancer in the Young: Assessing the Tumor Biology.

BACKGROUND: The overall incidence of colon cancer (CC) is decreasing, but with increasing early-onset colon cancer (EOCC < 50 years old). Our recent study revealed unique overexpression of cartilage oligomeric matrix protein (COMP) in EOCC and its association with aggressiveness. The aim of this study was to assess CC biology, especially in the young, by evaluating the role of COMP in CC carcinogenesis and cancer progression, detecting COMP in serum and its association with disease stage. STUDY DESIGN: Cancer and matching noninvolved tissue blocks from 12 sporadic EOCC and late-onset colon cancer (LOCC) patients of 4 disease stages were obtained from pathology archives. Ribonucleic acid expression profiling of 770 cancer-related genes using nCounter platform was performed. The COMP levels from 16 EOCC and LOCC serum samples were measured by ELISA. Carcinoembryonic antigen levels from these 16 samples were taken at the time of diagnosis. Transwell assay was performed to elucidate the role of COMP in motility and metastases. RESULTS: Expression profiling revealed increased COMP levels in higher disease stage. There was 7-fold higher COMP expression (p ≤ 0.05) in stage III compare to stage I and its coexpression with GAS1, VEGFC, MAP3K8, SFRP1, and PRKACA. Higher COMP expression was seen in stage II compared with stage I (p = 0.07) and its coexpression withTLR2, IL8, RIN1, IRAK3, and CACNA2D2, and COMP was detectable in serum and showed significantly higher levels in EOCC compared with LOCC. Similar correlation was seen with CEA levels, but the difference was not significant. Transwell assay revealed significantly increased motility of HT-29 cells after treatment with recombinant COMP. CONCLUSIONS: These findings suggest different tumor biology between EOCC and LOCC. Cartilage oligomeric matrix protein plays a significant role in CC carcinogenesis and has potential as biomarker for CC, especially aggressive EOCC.

Effect of Hyperbaric Oxygen on Proliferation and Gene Expression of Human Chondrocytes: An In Vitro Study.

PURPOSE: The present study investigated the effects of hyperbaric oxygen (HBO) on human chondrocyte proliferation and gene expression patterns. METHODS: Chondrocyte cultures were transferred to a HBO chamber and exposed to 100% oxygen for 7 consecutive days. Within groups, pressure was varied between 1 and 2 atm and duration of HBO administration was varied among 60, 90, and 120 minutes. Cell counts were performed using the WST-1 assay at 1, 3, 5, and 7 days after initiation of HBO treatment to obtain data to plot a growth curve. Gene expression of apoptosis markers PARP and caspase 3, as well as cartilage specific proteins collagen II and COMP, were detected by reverse transcription polymerase chain reaction. RESULTS: The experiments showed that in vitro administration of HBO inhibit chondrocyte growth. When applied compression was increased up to 2 atm, chondrocyte cell count was reduced by half at days 3 and 7 in association with an upregulation of the apoptosis markers PARP and caspase 3 as well as the cartilage specific proteins collagen II and COMP. No significant differences were monitored from varied duration of daily treatment. CONCLUSION: Chondrocyte growth was inhibited in vitro by treatment of HBO. This inhibitory effect was even increased by elevating the applied pressure, while molecular testing showed reduced chondrocyte growth. Higher levels of HBO inhibited cell growth even more, but up-regulation of apoptosis specific markers and cartilage specific proteins were seen during administration of high oxygen levels. Thus, it has to be evaluated that there is a critical level of hypo-/hyperoxia required to stimulate or at least maintain chondrocyte cell proliferation.

Cartilage oligomeric matrix protein is a prognostic factor and biomarker of colon cancer and promotes cell proliferation by activating the Akt pathway.

PURPOSE: Recent studies have determined that cartilage oligomeric matrix protein (COMP) plays a vital role in carcinogenesis. We sought to clarify the role of COMP in colon cancer. METHODS: We investigated gene expression data from The Cancer Genome Atlas (TCGA) dataset. Tissue microarrays (TMA) containing paired samples from 253 patients with colon cancer were subjected to immunostaining. COMP levels in serum of colon cancer patients and healthy donors were measured with ELISA. We established COMP-knockout cells using the CRISPR/Cas9 system and COMP-overexpressing cells using lentiviral vectors to detect the effects of COMP on colon cancer cells using Cell Counting Kit-8 (CCK8), colony formation, apoptosis detection kit, and tumorigenesis assays in nude mice. RESULTS: The analysis of TCGA dataset and the results of the TMA suggested that COMP expression levels were significantly higher in cancer tissues than in adjacent normal tissues. Moreover, high COMP expression was correlated with the poor outcome of colon cancer patients. COMP levels in the sera of preoperative patients with colon cancer were much higher than those in healthy donors and were significantly reduced after colectomy. Colon cancer cells without COMP were defective with respect to the ability to proliferate, colony formation, the ability to resist 5-Fluorouracil-induced apoptosis and the growth of xenograft tumors in mice. Contrasting results were observed in COMP overexpressed cells. COMP promoted colon cancer cell proliferation partially through the activation of PI3K/ Akt/ mTOR/ p70S6K pathway. CONCLUSIONS: COMP may be a novel prognostic indicator and biomarker and also a potential therapeutic target for colon cancer.