Oct-4 expression status in gastric cancer tumor tissue

İntroduction: Gastric cancer ?after lung cancer- is still the second common cause of death. The increasing knowledge and understanding about the mechanisms of development of gastirc cancer will light the way for new treatment options. As is known, one of the theories about cancer development is the stem cell theory. Human somatic stem cells are known to be in different tissues as in umblical cord blood, in bone marrow, and in hair follicle. Cells like embryonal stem cell and stem cell markers have been defined in solid tumours like brain, breast, colon, germ cell, and gastric cancer. OCT-4 is a transcription protein that exists in embryonic stem cells. It is coded by the namesake gene and gives the cells the ability of proliferation by themselves. On the other hand the relationship between infection-inflammation and cancer is well known. A relation like that has been proved between gastric cancer and chronic H. pylori infection. The inflammation caused by the chronic infection with H. pylori, and the engraftment of the stem cells- originated from the bone marrow- to the gastric tissue which is characterised by inflammation may be one of the possible mechanisms of gastric cancer development. In the light of the considerations mentioned above the aim of the study was to research mainly two theories. First, is there a relationship between the existence of embryonal stem cells, for example markers like the OCT-4 which belongs to cells for this period of time and the development of gastric adenocancer? Do these cells play a role of gastric adenocancer development? Second, if we show the OCT-4 expression in the tissues with gastric cancer cells, could we see this expression in an exaggerated way in proved H.pylori existence?Method: Patients with known gastric cancer and who were searched for H.pylori were enrolled to the study. To stain for immune histochemistry with OCT-4 on the paraffin blocks of the patients, the preparations of a total of fifty patients were assessed for nuclear staining. Positive stainings were scored. The correlation about accompanied H.pylori was studied, too.Results: For a total of fifty patients, in 52% of them positivity was found on immune histochemical evaluation for OCT-4 existence. There was nor positive neither negative correlation with OCT-4 staining and age, gender, tumoural staging, tumour localisation, tumour type, and H.pylori. But there was a significant relation with the tumoural differantiation degree. As the differantiation decreases, the frequency of expression increases.Conclusion: Embryonal stem cells are one of the possible mechanisms in the molecular pathogenesis of gastric cancer. Although it could not be shown that H.pylori infection plays a role in migration of the embryonal somatic stem cells to stomach, the final word has not been said yet.Key Words: gastric cancer, OCT-4, pathogenesis