Clin Exp Pharmacol Physiol. 2017;44:1099–1105. wileyonlinelibrary.com/journal/cep | 1099 © 2017 John Wiley & Sons Australia, Ltd Received: 23 May 2017 | Revised: 10 July 2017 | Accepted: 25 July 2017 DOI: 10.1111/1440-1681.12840 ORIGINAL ARTICLE Differential expression of two genes Oct-4 and MUC5AC associates with poor outcome in patients with gastric cancer Milad Javanbakht 1 | Jamal Akhavanmoghadam 2 | Amir Jouya Talaei 3 | Maryam Aghyani 4 | Mohamad Mozafari 4,5 | Leila Khedmat 6 | Mahdi Mohebbi 4 1 School of Medicine Science, Islamic Azad University, Sarab, Iran 2 Trauma Research Center, Baqiyatallah University of Medical Sciences, Tehran, IR, Iran 3 Department of Genetics, Faculty of Life Science, Azad University of Tehran Medical Sciences Branch, Tehran, Iran 4 General practitioner (GP), Doctor of Medicine (MD), Tehran and Tabriz, Iran 5 Graduated from Tabriz University of Medical Science, Tabriz, Iran 6 Department of Social Medicine, Tehran University of Medical Sciences, Tehran, Iran Correspondence Mohamad Mozafari, Graduated from Tabriz University of Medical, Science, Tabriz, Iran. Email: mohamad2mzf@gmail.com Leila Khedmat, Department of Social Medicine, Tehran University of Medical Sciences, Tehran, Iran. Email: leilakhedmat@yahoo.com Summary Gastric cancer (GC) is the most frequent leading cause of cancer-associated mortality worldwide that is linked to poor prognosis due to the lack of appropriate biomarkers. Our aim was to evaluate the MUC5AC and Oct-4 expression levels in GC and to assess their association with clinical factors. Immunohistochemical analysis (IHC) and qRT- PCR were performed in GC patients to examine the MUC5AC and Oct-4 expression levels. The mRNA level of MUC5AC was significantly decreased in tumour tissues compared with non-cancerous tissues (1.11 ± 0.69 vs 3.7 ± 0.71; P = .024). On the other hand, Oct-4 mRNA level was upregulated in tumour tissues as compared to normal tissues (2. 86 ± 0.78 vs 0.87 ± 0.54; P = .0015). Decreased expression of MUC5AC was detected in 27 patients (67.5%), while high to moderate expression levels were observed in 13 cases (32.5%), but in normal tissues the expression levels of MUC5AC were increased (P = .001). The decreased expression of MUC5AC was associated with aggressive tumour characteristics, such as TNM stage (P = .023), his- tologic type (P = .012) and lymph node metastasis (P = .001). High expression of Oct-4 was detected in 24 tumour tissues (60%), while 16 cases (40%) showed low expression level. Increased Oct-4 expression was correlated with clinicopathological characteris- tics such TNM stage (P = .002), histologic type (P = .008) and lymph node metastasis (P = .001). Our results showed that high Oct-4 expression and the reduction of MUC5AC expression may be involved in the progression and an unfavorable progno- sis of GC. KEYWORDS gastric cancer, IHC, MUC5AC, Oct-4, QRT-PCR 1 | INTRODUCTION Despite development of therapeutic strategies, the clinical outcome of gastric cancer (GC) remains poor. However, effective prognostic/pre- dictive markers for multimodal therapy are currently required. Mucins are a group of extremely glycosylated extracellular ingredients of the mucousal layer. Mucins have been described to be linked to protection, lubrication and hydration of the external surface of human epithelial tissue layers. It has been reported that expression and glycosylation of mucins are associated with carcinogenesis including invasion, prolifer- ation and regulation of tumour cells. 1-3 MUC5AC mucin has protective role in the surface of the stomach from chemical, microbial and, me- chanical damage. 4 MUC5AC was reported to be implicated in gastric carcinogenesis with Lowe level of expression. Moreover, it has been indicated that MUC5AC expression level can be linked to severity of GC. 5-7 Downregulation of MUC5AC expression has been determined in certain neoplastic lesions and might be appeared in advanced GC. 8-11 Oct-4 has been revealed that it associated with the