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.

Lanreotide vs octreotide LAR for patients with advanced gastroenteropancreatic neuroendocrine tumors: An observational time and motion analysis.

BACKGROUND: Lanreotide and octreotide acetate suspension for injectable (LAR) are both recommended for clinical use in patients with locally advanced or metastatic gastroenteropancreatic neuroendocrine tumors. However, each agent possesses unique attributes in terms of their drug-delivery characteristics. The study objective was to compare overall drug-delivery efficiency between lanreotide and octreotide LAR in gastroenteropancreatic neuroendocrine tumor patients. METHODS: This study employed an observational time and motion design among patients treated with lanreotide or octreotide LAR across five US cancer centers. Baseline patient data collection included age, disease grade and duration, prior therapies and performance status. Drug-delivery time (drug preparation and administration), total patient time and resource use data were collected for gastroenteropancreatic neuroendocrine tumors receiving lanreotide (n = 22) or octreotide LAR (n = 22). Following each administration, qualitative data on the drug-delivery experience was collected from patients and nurses. RESULTS: Lanreotide was associated with a significant reduction in mean delivery time (2.5 min; 95% CI:2.0 to 3.1) compared to octreotide LAR (6.2 min; 95%CI: 4.4 to 7.9; p = 0.004). The mean total patient time for lanreotide and octreotide LAR was comparable between groups (32.1 vs. 36.6 minutes; p = 0.97). Nurses reported increased concerns with octreotide LAR related to needle clogging (p = 0.034) and device failures (p = 0.057). Overall, lanreotide had a median satisfaction score of 5.0 compared to a score of 4.0 with octreotide LAR (p = 0.03). CONCLUSIONS: Lanreotide was associated with significant reductions in drug-delivery time compared to octreotide LAR, which contributed to an improvement in overall healthcare efficiency. TRIAL REGISTRATION: clinicaltrials.gov Identifier: NCT03017690.

18O-exchange evidence that mutations of arginine in a signature sequence for P-type pumps affect inorganic phosphate binding.

We have proposed a model for part of the catalytic site of P-type pumps in which arginine in a signature sequence functions like lysine in P-loop-containing enzymes that catalyze adenosine 5'-triphosphate hydrolysis [Smirnova, I. N., Kasho, V. N., and Faller, L. D. (1998) FEBS Lett. 431, 309-314]. The model originated with evidence from site-directed mutagenesis that aspartic acid in the DPPR sequence of Na,K-ATPase binds Mg(2+) [Farley, R. A., et al. (1997) Biochemistry 36, 941-951]. It was developed by assuming that the catalytic domain of P-type pumps evolved from enzymes that catalyze phosphoryl group transfer. The functions of the positively charged amino group in P-loops are to bind substrate and to facilitate nucleophilic attack upon phosphorus by polarizing the gamma-phosphorus-oxygen bond. To test the prediction that the positively charged guanidinium group of R596 in human alpha(1) Na,K-ATPase participates in phosphoryl group transfer, the charge was progressively decreased by site-directed mutagenesis. Mutants R596K, -Q, -T, -M, -A, -G, and -E were expressed in yeast membranes, and their ability to catalyze phosphorylation with inorganic phosphate was evaluated by following (18)O exchange. R596K, in which the positive charge is retained, resembled the wild type. Substitution of a negative charge (R596E) resulted in complete loss of activity. The remaining mutants with uncharged side chains had both lowered affinity for inorganic phosphate and altered phosphate isotopomer distributions, consistent with increased phosphate-off rate constants compared to that of the wild type. Therefore, mutations of R596 strengthen our hypothesis that the oppositely charged side chains of the DPPR peptide in Na,K-ATPase form a quaternary complex with magnesium phosphate.