Zinc: A promising agent in dietary chemoprevention of cancer.

Proper intake of dietary nutrients is considered crucial for preventing the initiation of events leading to the development of carcinoma. Many dietary compounds have been considered to contribute in cancer prevention including zinc, which plays a pivotal role in host defense against the initiation and promotion of several malignancies. Zinc is an essential element that is integral to many proteins and transcription factors which regulate key cellular functions such as the response to oxidative stress, DNA replication, DNA damage repair, cell cycle progression, and apoptosis. Zinc has been ascribed roles in the metabolism and interaction of malignant cells, particularly in apoptosis. Zinc is involved in structural stabilization and activation of the p53 that appears to be an important component of the apoptotic process and also in activation of certain members of the caspase family of proteases. Zinc exerts a positive beneficial effect against chemically induced preneoplastic progression in rats and provides an effective dietary chemopreventive approach to disease in vulnerable section of population with family history of carcinoma. The present review provides an insight into the research conducted on animals as well as on human subjects for providing the concept that zinc deficiency is an important factor in the development and progression of malignancy and that zinc could be efficacious in the prevention and treatment of several cancers viz., colon, pancreas, oesophageal and head and neck. However, it needs further exploration with regard to other definitive bioassays including protein expression and documentation of specific molecular markers to establish the exact mechanism for zinc-mediated cancer chemoprevention. Preclinical trials need to investigate the genetic and epigenetic pathways of chemoprevention by zinc.

A study on the time-dependent expression of caspase-6 during repair of skin contusion in rats / 法医学杂志

OBJECTIVE@#To investigate the expression of caspase-6 in rat skin contusion and its surrounding areas during repairment.@*METHODS@#Immunohistochemical SP method and Western blot technique were used to study the expression and activation of caspase-6 in rat skin contusion and its surrounding areas.@*RESULTS@#Weak expression of caspase-6 was detected in cytoplasms of polymorphonuchear cells (PMNs) infiltrated in the injured area at 3 hours post-contusion. The ratio of the caspase-6 positive cells was low (25.78 +/- 1.38)%. The expression of caspase-6 was increased prominently (47.70 +/- 5.14)% at 12 hours post-contusion. Almost all of the PMNs, mononuclear cells (MNCs) and fibroblastic cells (FBCs) were caspase-6 positive with both cytoplasm and nucleus staining (54.58 +/- 5.64)% on post-contusion day 3. The expression of caspase-6 decreased gradually thereafter. The expression of the 34-kDa pro-caspase-6 was detected by Western blot in both control and the post-contusion groups with time dependent dynamics.@*CONCLUSION@#These results suggest that caspase-6 may play a major role in trauma-induced inflammatory response. Since caspase-6 shows a timely dependent expression in PMNs, MNCs and FBCs during skin injury repair in rat, it may be used as a marker for the contusion age determination,