Expression of NASG gene and its role in human nasopharyngeal homogenous tissue cells.

Background: The NASG gene has been confirmed as a tumor-suppressor gene candidate related to nasopharyngeal carcinoma (NPC) by previous studies. We further investigated the expression and the role of NASG in the homogeneous tissue cells by microdissecting the samples of tissue from human NPC, and introduced a new way to study the expression of specific genes in tumor tissue.

Methods: The RNAlater reagent was used to preserve the samples of tissue from the nasopharynx of NPC patients. The samples were microdissected to harvest the homogeneous tissue cells and then total RNA was isolated from them. The antisense RNA (aRNA) was amplified from the total RNA by "in vitro transcription (IVT)". We investigated NASG expression in the homogeneous tumor cells of NPC (22 samples) and compared it with that in the pure epithelial pillar cells of normal nasopharyngeal (10 samples) by semi-quantitative reverse transcription-polymerase chain reaction (sqRT-PCR).

Results: The high quality total RNA could be harvested from the microdissected homogeneous tissue cells of the nasopharynx, then sufficient aRNA was derived from it. NASG gene expression was identified using aRNA by sqRT-PCR and showed that there was significant difference between the average value of case groups and that of control group (t = -5.275, df = 30, P < 0.001). The NASG gene in the subgroups WHOII tended to express lower levels than those in the subgroup WHOIII although this difference was not statistically significant (t = -1.584, df = 20, P = 0.129 > 0.05).

Conclusions: Microdissection was an effective method to obtain the homogeneous tissue cells of nasopharyngeal tissue (including the samples of NPC and non-NPC) in our study. Sufficient aRNA from amplifying total RNA could be used in sqRT-PCR to analyse the expression of NASG in the pure tissue cells. NASG should be a tumor-suppression gene candidate regarding to NPC.