MUC5AC

Mucin 5AC, also known as MUC5AC, is a human gene. The Mucin 5AC antigen is found in columnar mucous cells of surface gastric epithelium and in goblet cells of the fetal and precancerous colon but not in normal colon cells. Mucin genes are expressed in a regulated cell- and tissue-specific manner. MUC1 is detected in mucous cells of the surface epithelium and neck region of the gastric antrum, as well as in pyloric glands and oxynthic glands of the body region. MUC5AC is highly expressed in foveolar epithelium of both body and antrum, whereas MUC6 protein expression is limited to mucous neck cells of the body and pyloric glands of the antrum.

The mucin expression pattern of Gastric Carcinoma is heterogeneous. It includes mucins normally expressed in gastric mucosa (MUC1, MUC5AC and MUC6) and de novo expression of the intestinal mucin MUC2. The heterogeneous pattern of mucin expression, including the expression of the intestinal mucin MUC2, may provide new insights into the differentiation pathways of Gastric Carcinoma. It has been shown that in Gastric Carcinomas evaluated for expression of several mucins (MUC1, MUC2, MUC5AC and MUC6), mucin expression is associated with tumor type (MUC5AC with Diffuse and Infiltrative Carcinomas and MUC2 with Mucinous Carcinomas) but not with the clinico-biological behavior of the tumors. Mucin expression is associated with tumor location (MUC5AC with Antrum Carcinomas and MUC2 with Cardia Carcinomas), indirectly reflecting differences in tumor differentiation according to tumor location.

MUC5AC is a mouse monoclonal antibody derived from cell culture supernatant that is concentrated, dialyzed, filter sterilized and diluted in buffer pH 7.5, containing BSA and sodium azide as a preservative.

1. Reis CA, et al. Int J Cancer. 1997;74:112-121
2. Kim GE, et al. Gastroenterology. 2002;123(4):1052-60

1. Cut and mount 3-4 micron formalin-fixed paraffin-embedded tissues on positive charged slides.
2. Air dry for 2 hours at 58° C.
3. Deparaffinize, dehydrate and rehydrate tissues.
4. Subject tissues to heat epitope retrieval using a suitable retrieval solution such as ImmunoDNA Retriever with Citrate (BSB 0020-BSB 0023) or EDTA (BSB 0030-BSB 0033).
5. Any of three heating methods may be used:
   • Electric Pressure Cooker
     Place standoff rack at base of pressure cooker. Add 1-2 inches of distilled water to the pressure cooker and turn heat to high, and incubate for 15 minutes. Open and immediately transfer slides to room temperature.
   • Water Bath Method
     Place tissues/slides in a pre-warmed staining dish or coplin jar containing the ImmunoDNA Retriever with Citrate or EDTA in a water bath set at 95°-99° C. Incubate for 30-60 minutes.
   • Conventional Steamer Method
     Place tissues/slides in a pre-warmed staining dish or coplin jar containing the ImmunoDNA Retriever with Citrate or EDTA in a Steamer, cover and steam for 30-60 minutes.
6. After heat treatment, transfer slides in ImmunoDNA Retriever with Citrate or EDTA to room temperature and let stand for 15-20 minutes.
7. Wash slides with IHC wash buffer or DI water.
8. Continue IHC staining protocol.