| Background Spinal metastasis is an important disease with a severely impairment on humanity health, which are associated with high cripples rate and mortality. With the increasing incidence of primary malignant tumors and prolonging survival time of patients with cancers for the development of anticancer therapy, there is a tendency that the incidence of spinal metastases climbs year by year rapidly. It was estimated in the past that about 40% of patients with malignant tumors developed spinal metastases. However, it was reported recently that the number came up to 70%. Lung cancer is the most common malignant tumor in China. A lot of patients were found spinal metastases when they were diagnosed with lung cancer. Conditions that occurs with spinal metastases such as osteolysis of bone, collapse of vertebrae, instability of spine column and compression of spinal cord often lead to severe pain, neurological functional impairment even plegia, then result in decrease of life quality and survival time. Surgical treatment takes an important position in therapy of spinal metastases, which plays an irreplaceable role in removing of lesion, decompression of nerve, reconstruction of spinal stability. However, because of the limited survival time, there is and obvious controversy in determination of treatment strategy, especially on spinal metastases from lung cancer and liver cancer.With the rapid development of molecular biology, great progress was achieved in research of tumor-related genes. Stem cell has become one of most breathtaking research areas of biomedical sciences. There is now compelling evidence that the bulk of the malignant cells in cancers are generated by rare fractions of self-renewing, multipotent, and tumor-initiating cells, termed cancer stem cells(CSCs). Whether CSCs arise from normal stem cells or more differentiated cells is not known. Nevertheless, CSCs resemble the normal stem or progenitor cells of the corresponding tissue of origin.Molecular biomarkers with tumor occurring and prognostic value were identified in research of primary tumors such as brain tumor, liver cancer, breast cancer, colon cancer and leukemia, and were successfully applied to clinical medicine. CD133 is one of the special markers of cancer stem cells and can express significantly in some malignant solid tumors.The POU-domain transcription factor OCT4 is associated with the pluripotent state of cells comprising the inner cell mass of pre-implantation embryos and has been known to play a critical role in the maintenance of pluripotency of embryonic stem cells. Reactivation of OCT4 expression ispostulated to occur in differentiated cells that have under-gone carcinogenesis, or tumor formation. A few studies on metastatic tumors were reported at home and abroad while report on spinal metastasis was rare.Objective To study the expression of cancer stem cell marker CD133 and embryonic stem cell marker Oct4 in the spinal metastatic tissues of lung cancer, and to search for the evidence in support of the cancer stem cell theory and research the relationship of the markers expression between clinical features.Methods A total of 41 cases of spinal metastases from lung cancer underwent operation in Shanghai Changzheng Hospital from Jan.1999 to Dec.2007 with complete clinical and follow up data was involved in this study. And twenty paravertebral normal tissues (two centimeters from the tumor's edge) of lung cancer cases were also studied. In which,29 were male while 12 were female, whose ages ranged from 34 to 76 years (mean 56 years).All patients in this group didn't receive any chemotherapy, radiotherapy or surgery aiming at the primary sits. Immunohistochemistry was used to detected the expression of cancer stem marker CD133 and embryonic stem cell marker Oct4 in the spinal metastatic tissues of lung cancer. The correlations of the expression of the markers with age, gender, involvement site, number of vertebral involvement, pathological types and degree of differentiation of cancer were analyzed. The SPASS statistical software were used in analyses on relationship between each marker and biological behavior of the cancer.Results 1.The positive expression rate of cancer stem cell marker CD133 was 90.2% in 41 spinal metastatic cases of lung cancer. Only two cases have positive expression in normal group. Obvious significance was detected between the experiment group and the normal group (P<0.01).2. The positive expression rate of embryonic stem cell marker Oct4 was 43.2% in 41 spinal metastatic cases of lung cancer. There was no positive expression in the normal group. Obvious significance was detected between the experiment group and the normal group(P<0.01).3. No significant correlations were found between the positive expression of CD133 and clinical pathological indexes including age, gender, involvement site, number of vertebral involvement, pathological types and degree of differentiation of cancer(P>0.05).4. No significant correlations were found between the positive expression of Oct4 and clinical pathological indexes including age, gender, involvement site, number of vertebral involvement, pathological types and degree of differentiation of cancer(P＞0.05).Conclusion The significant expression of cancer stem cell marker CD133 implied that there were stem-like cells existing in the spinal metastatic tissue of lung cancer. Although the expression of Oct4 was lower than that of CD133, it might relate to the differentiation and tumor. More research should be performed to discover the relationship of CD133 and Oct4 and cancer metastasis.
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