Irrespective of the morphological features of end-stage cell death (that may be apoptotic, necrotic, autophagic, or mitotic), mitochondrial membrane permeabilization (MMP) is frequently the decisive event that delimits the frontier between survival and death. Thus mitochondrial membranes constitute the battleground on which opposing signals combat to seal the cell's fate. Local players that determine the propensity to MMP include the pro- and antiapoptotic members of the Bcl-2 family, proteins from the mitochondrialpermeability transition pore complex, as well as a plethora of interacting partners including mitochondrial lipids. Intermediate metabolites, redox processes, sphingolipids, ion gradients, transcription factors, as well as kinases and phosphatases link lethal and vital signals emanating from distinct subcellular compartments to mitochondria. Thus mitochondria integrate a variety of proapoptotic signals. Once MMP has been induced, it causes the release of catabolic hydrolases and activators of such enzymes (including those of caspases) from mitochondria. These catabolic enzymes as well as the cessation of the bioenergetic and redox functions of mitochondria finally lead to cell death, meaning that mitochondria coordinate the late stage of cellular demise. Pathological cell death induced by ischemia/reperfusion, intoxication with xenobiotics, neurodegenerative diseases, or viral infection also relies on MMP as a critical event. The inhibition of MMP constitutes an important strategy for the pharmaceutical prevention of unwarranted cell death. Conversely, induction of MMP in tumor cells constitutes the goal of anticancer chemotherapy.

Mitochondrial Membrane Permeabilization in Cell Death

The Montreal Definition and Classification of Gastroesophageal Reflux Disease: A Global Evidence-Based Consensus

While hypoxia-inducible factor (HIF) is a major actor in the cell survival response to hypoxia, HIF also is associated with cell death. Several studies implicate the HIF-induced putative BH3-only proapoptotic genes bnip3 and bnip3l in hypoxia-mediated cell death. We, like others, do not support this assertion. Here, we clearly demonstrate that the hypoxic microenvironment contributes to survival rather than cell death by inducing autophagy. The ablation of Beclin1, a major actor of autophagy, enhances cell death under hypoxic conditions. In addition, the ablation of BNIP3 and/or BNIP3L triggers cell death, and BNIP3 and BNIP3L are crucial for hypoxia-induced autophagy. First, while the small interfering RNA-mediated ablation of either BNIP3 or BNIP3L has little effect on autophagy, the combined silencing of these two HIF targets suppresses hypoxia-mediated autophagy. Second, the ectopic expression of both BNIP3 and BNIP3L in normoxia activates autophagy. Third, 20-mer BH3 peptides of BNIP3 or BNIP3L are sufficient in initiating autophagy in normoxia. Herein, we propose a model in which the atypical BH3 domains of hypoxia-induced BNIP3/BNIP3L have been designed to induce autophagy by disrupting the Bcl-2-Beclin1 complex without inducing cell death. Hypoxia-induced autophagy via BNIP3 and BNIP3L is clearly a survival mechanism that promotes tumor progression.

/pdf/hypoxia-induced-autophagy-is-mediated-through-hypoxia-2i88mtp3bn.pdf

Hypoxia-Induced Autophagy Is Mediated through Hypoxia-Inducible Factor Induction of BNIP3 and BNIP3L via Their BH3 Domains

American Gastroenterological Association technical review on the management of Barrett's esophagus.

http://www.jbc.org/content/287/23/19094.full.pdf

Microtubule-associated Protein 1 Light Chain 3 (LC3) Interacts with Bnip3 Protein to Selectively Remove Endoplasmic Reticulum and Mitochondria via Autophagy

Any alteration in the synthesis and breakdown of the extracellular matrix is important in tissue remodeling during inflammation and wound healing. The degradation of the extracellular matrix components is regulated by a cascade of matrix metalloproteinases (MMPs). The present study attempted to assess the relationship between MMPs and the degree of inflammation in ulcerative colitis. Methods: The expression of MMPs, including MMP-1, -2, -3, -7 (matrilysin), and -9, and that of their inhibitors (tissue inhibitor of metalloproteinases [TIMP]-1 and -2) were analyzed immunohistochemically by using 52 formalin-fixed and paraffin-embedded specimens from patients with ulcerative colitis who had undergone a biopsy or surgery. Results: It was observed that MMP-1, -2, and -9, and the TIMPs were expressed in stromal cells, MMP-3 was expressed in both the epithelial cells and stromal components, and matrilysin was expressed only in the epithelial cells on the edge of ulcers. The expression of the MMPs was increased compared with that of the TIMPs. The frequency of matrilysin expression was increased corresponding to the severity of the inflammation. Matrilysin was also expressed in epithelial cells with dysplasia and cancer. Conclusions: Matrilysin expression could be an important marker of activity and could be used for the prediction of subsequent transformation in patients with ulcerative colitis.

The expression of matrix metalloproteinase matrilysin indicates the degree of inflammation in ulcerative colitis

Purpose: The aim of this study was to characterize the relationship of insulin-like growth factor (IGF)-II expression with IGF-I, IGF-I receptor (IGF-IR), cyclooxygenase-2 (COX-2), and matrix metalloproteinase (MMP)-7 in early colorectal carcinogenesis. Experimental Design: With the semiquantitative reverse transcriptase-PCR, 90 human colorectal tumor tissues (63 adenomas and 27 submucosal pT1 cancers) were analyzed for IGF-II, IGF-IR, IGF-I, COX-2, and MMP-7 expression. Ninety-nine adenoma tissues and 60 pT1 cancer tissues were also analyzed immunohistochemically for IGF-II expression. Loss of imprinting of the IGF-II gene was analyzed. Paired carcinoma and adenoma tissues obtained from a carcinoma in adenoma lesion was analyzed by a cDNA array. Results: IGF-II mRNA expression was detected in 37.8% of the 90 colorectal tumor tissues. The frequency of IGF-II mRNA expression was significantly higher in pT1 cancer (70.4%) than in adenoma (23.8%). Immunohistochemical IGF-II expression was also more frequently detected in pT1 cancer (58.3%) than in adenoma (25.3%). Loss of imprinting of the IGF-II gene was observed in 15 (44.1%) of the 34 colorectal tumors in which IGF-II was overexpressed. IGF-II expression was positively correlated with the expression of IGF-IR and IGF-I. COX-2 and MMP-7 mRNA expression was detected in 42.2% and 77.8% of the tumor tissues, respectively, and both were positively correlated with IGF-I, IGF-II, and IGF-IR expression. IGF-II was the most differentially expressed gene between carcinoma and adenoma lesions. Conclusions: IGF-II, in conjunction with IGF-IR, IGF-I, COX-2, and MMP-7, seems to play a key role in the early stage of colorectal carcinogenesis.

https://clincancerres.aacrjournals.org/content/clincanres/10/23/7950.full.pdf

Interplay of insulin-like growth factor-II, insulin-like growth factor-I, insulin-like growth factor-I receptor, COX-2, and matrix metalloproteinase-7, play key roles in the early stage of colorectal carcinogenesis.

Little is known about the molecular biological features of large flat tumors or laterally spreading tumors (LSTs) of the colon and rectum. Methods: The cyclooxygenase (COX)–2 protein expression level of LSTs was assessed immunohistochemically and compared with that of exophytic colorectal tumors. COX-2 expression in the dysplastic epithelial cells and the interstitial cells was evaluated independently. Results: Sixty-five LSTs and 65 exophytic tumors were randomly selected from the archives, and 61 and 59, respectively, were successfully analyzed. LSTs showed significantly more intense COX-2 protein expression in the dysplastic epithelial cells than the exophytic tumors (P > 0.0001). COX-2-positive interstitial cells were also observed more frequently in LSTs than in the exophytic tumors (P = 0.015). Conclusions: Overexpression of COX-2 protein may play a crucial role in the tumorigenesis of colorectal LSTs. Chemoprevention, using nonsteroidal anti-inflammatory drugs (NSAIDs) or selective COX-2 inhibitors may be effective for treating this unique neoplasm, which sometimes defies endoscopic treatment.

Takao Endo

Papers

The expression of matrix metalloproteinase matrilysin indicates the degree of inflammation in ulcerative colitis

Interplay of insulin-like growth factor-II, insulin-like growth factor-I, insulin-like growth factor-I receptor, COX-2, and matrix metalloproteinase-7, play key roles in the early stage of colorectal carcinogenesis.

Increased cyclooxygenase-2 expression in large flat colorectal tumors (laterally spreading tumors).

Silencing of negative regulator of JAK/STAT in colorectal cancer.