Evaluation of Hippo Pathway and CD133 in Radiation Resistance in Small-Cell Lung Cancer

Although the Hippo pathway and CD133 have been reported to play pertinent roles in a variety of cancer, knowledge about their contribution to radiation resistance in small-cell lung cancer (SCLC) is limited. In this first-of-a-kind study, we have reported the expression of key Hippo pathway proteins in SCLC patients by immunohistochemical staining. We assessed the involvement of yes-associated protein 1 (YAP1) in radiation resistance by Cell Counting Kit-8 (CCK-8) and flow cytometry. In addition, we analysed the impact of CD133 on radiotherapy for SCLC. The mammalian Ste20-like serine/threonine kinase 2(MST2), pMST2, and pYAP1 in the Hippo pathway were not significantly associated with the disease stage and survival time in patients with SCLC. However, the pYAP1 expression showed some significance in the “YAP/TAZ subgroup” of SCLC patients. The proportion of CD133 in the SCLC cells was controlled by the YAP1 expression. The CD133 and YAP1 levels were significantly correlation with each other in tissues of SCLC patients. We sorted and isolated the CD133(+) and CD133(−)cells in H69 and found that the cell surface glycoprotein may be associated with the radiation resistance of SCLC.In summary, we have firstly reported the expression of key Hippo pathway proteins in SCLC patients. Furthermore, we also identified that CD133 may be controlled by the expression of YAP1 in the Hippo pathway and that CD133 may be associated with the radiation resistance of SCLC.