elafin and Colonic-Neoplasms

Patients with UICC/AJCC stage II colon cancer have a high 5-year overall survival rate after surgery. Nevertheless, a significant subgroup of patients develops tumour recurrence. Currently, there are no clinically established biomarkers available to identify this patient group. We applied reverse-phase protein arrays (RPPA) for phosphatidylinositide-3-kinase pathway activation mapping to stratify patients according to their risk of tumour recurrence after surgery.. Full-length proteins were extracted from formalin-fixed, paraffin-embedded tissue samples of 118 patients who underwent curative resection. RPPA technology was used to analyse expression and/or phosphorylation levels of six major factors of the phosphatidylinositide-3-kinase pathway. Oncogenic mutations of KRAS and BRAF, and DNA microsatellite status, currently discussed as prognostic markers, were analysed in parallel.. Expression of phospho-AKT (HR=3.52; P=0.032), S6RP (HR=6.3; P=0.044), and phospho-4E-BP1 (HR=4.12; P=0.011) were prognostic factors for disease-free survival. None of the molecular genetic alterations were significantly associated with prognosis.. Our data indicate that activation of the PI3K/AKT pathway evidenced on the protein level might be a valuable prognostic marker to stratify patients for their risk of tumour recurrence. Beside adjuvant chemotherapy targeting of upregulated PI3K/AKT signalling may be an attractive strategy for treatment of high-risk patients.

Topics: Adult; Aged; Aged, 80 and over; Biomarkers, Tumor; Colonic Neoplasms; Disease-Free Survival; Elafin; Female; Humans; Kaplan-Meier Estimate; Male; Middle Aged; Mutation; Neoplasm Recurrence, Local; Neoplasm Staging; Prognosis; Proto-Oncogene Proteins c-akt; Signal Transduction

Poly ADP-ribose polymerase (PARP) which is closely related to Poly ADP-ribose glycohydrolase (PARG) has already been thoroughly investigated in both experimental and clinical cancer trials compared to the latter. Nevertheless, in this experiment the importance of PARG expression was highlighted; whereby it is being silenced via lentivirus vector-mediated short hairpin RNA (shRNA). MTT assay showed that there was an inhibition in human Lovo colon cancer cell growth and flow cytometry demonstrated an increase in the population of cells in G(0)/G(1) phase with a decrease in the S phase in transfected Lovo cells. Furthermore, our results suggested that the effect of silencing PARG leads to the inhibition of PARP expression; related to a decrease in the expression of Nuclear Factor Kappa-B (NFκ-B) with an increase in Akt(473) phosphorylation; suggesting that the Phosphoinositol 3-kinase (PI3K)/Akt/NFκ-B pathway is important for cellular growth and proliferation. Hence, this study emphasizes and converges on the relevance of silencing PARG which inhibits growth of human colonic cancer cells via PI3K/Akt/NFκ-B pathway; as colon carcinoma remains to be amongst one of the commonest cancers throughout the world with high morbidity and mortality rates.

Topics: Apoptosis; Blotting, Western; Cell Cycle; Cell Nucleus; Cell Proliferation; Colonic Neoplasms; Elafin; Flow Cytometry; GTPase-Activating Proteins; Humans; NF-kappa B; Phosphorylation; Proto-Oncogene Proteins c-akt; Real-Time Polymerase Chain Reaction; RNA, Messenger; Tumor Cells, Cultured

Due to poor tumour-associated vasculature, tumour cells are subjected to a fluctuating microenvironment with periods of limited oxygen and glucose availability. Adaptive mechanisms to adverse microenvironments are important for tumour cell survival. The cyclooxygenase (COX)-2/prostaglandin E(2) (PGE(2)) pathway has key roles in colorectal tumorigenesis. Although glucose is important as an energy source and in maintaining endoplasmic reticulum homeostasis, relatively little is known regarding how tumour cells adapt to the microenvironmental stress of reduced glucose availability. Here, we report the novel findings that glucose deprivation of colorectal tumour cells not only increases COX-2 expression but also decreases 15-hydroxyprostaglandin dehydrogenase (15-PGDH) expression, resulting in increased extracellular PGE(2). Furthermore, we have shown that PGE(2) promotes tumour cell survival during glucose deprivation. Glucose deprivation enhances phosphoinositide 3-kinase/Akt activity, which has a role in both the up-regulation of COX-2 and down-regulation of 15-PGDH. Glucose deprivation also activates the unfolded protein response (UPR) resulting in elevated C/EBP-homologous protein (CHOP) expression. Interestingly, inhibiting CHOP expression by small interfering RNA during glucose deprivation attenuates the reduction in 15-PGDH expression. This is the first report linking activation of the UPR with a reduction in expression of tumour-suppressive 15-PGDH and may have implications for tumour cells' ability to survive exposure to therapeutic agents that activate the UPR. Our data suggest that diverse microenvironmental stresses converge to regulate PGE(2) as a common and crucial mediator of cell survival during adaptation to the tumour microenvironment and may lead to novel chemopreventive and therapeutic strategies.

Topics: Blotting, Western; Cell Proliferation; Colonic Neoplasms; Cyclooxygenase 2; Dinoprostone; Elafin; Glucose; Humans; Hydroxyprostaglandin Dehydrogenases; Hypoxia; Proto-Oncogene Proteins c-akt; Real-Time Polymerase Chain Reaction; RNA, Messenger; Transcription Factor CHOP; Tumor Microenvironment; Unfolded Protein Response