The MUC1 mucin regulates the tumorigenic properties of human esophageal adenocarcinomatous cells

MUC1 is a membrane-bound mucin known to participate in tumor proliferation. It has been shown that MUC1 pattern of expression is modified during esophageal carcinogenesis, with a progressive increase from metaplasia to adenocarcinoma. The principal cause of development of esophageal adenocarcinoma is gastro-esophageal reflux and MUC1 was previously shown to be up-regulated by several bile acids present in reflux. In this report, our aim was thus to determine whether MUC1 plays a role in biological properties of human esophageal cancer cells. For that, a stable MUC1-deficient esophageal cancer cell line was established using a shRNA approach. In vitro (proliferation, migration and invasion) and in vivo (tumor growth following subcutaneous xenografts in SCID mice) biological properties of MUC1-deficient cells were analyzed. Our results show that esophageal cancer cells lacking MUC1 were less proliferative and had decreased migration and invasion properties. These alterations were accompanied by a decreased activity of NFKB p65, Akt and MAPK (p44/42, JNK and p38) pathways. MCM6 and TSG101 tumor-associated markers were also decreased. Subcutaneous xenografts showed a significant decrease in tumor size when cells did not express MUC1. Altogether, the data indicate that MUC1 plays a key role in proliferative, migrating and invasive properties of esophageal cancer cells as well as in tumor growth promotion. MUC1 mucin appears thus as a good therapeutic target to slow down esophageal tumor progression.     

Bioengineering aspects of biophotolysis

The practical aspects of producing hydrogen by photosynthetic microorganisms are reviewed. Various alternative concepts for hydrogen production are discussed, both single and two-stage systems. The best developed process currently is based on nitrogen-fixing heterocystous blue-green algae which can produce hydrogen and oxygen simultaneously. Solar energy conversion to hydrogen efficiencies of 0.2% averaged over several weeks have been obtained with outdoor systems. Practical systems would require a ten-fold increase in conversion efficiencies. Also, systems which produce pure hydrogen are preferred. Photosynthetic bacteria are of near-term applications. A general design for a biophotolysis system is proposed consisting of vertically arranged, thin-walled glass tubes with an inert gas recirculated through the cultures for mixing and removal of hydrogen. Gas mass transfer considerations, energy utilization, and economics favour such a system.     

Ecophysiological aspects of allelopathy

Allelochemicals play an important role in explaining plant growth inhibition in interspecies interactions and in structuring the plant community. Five aspects of allelochemicals are discussed from an ecophysiological perspective: (i) biosynthesis, (ii) mode of release, (iii) mode of action, (iv) detoxification and prevention of autotoxicity, and (v) joint action of allelochemicals. A discussion on identifying a compound as an allelochemical is also presented.