The present study investigated the expression of Toll-like receptor 4 (TLR4) and proteins involved in its associated signaling pathways in patients with classic Kaposi's sarcoma (KS) and acquired immune deficiency syndrome (AIDS)-associated KS (AIDS-KS) in Xinjiang Autonomous Region of China. A total of 35 patients with KS were enrolled in the present study between May 2011 and July 2013, including 26 cases of AIDS-KS and 9 cases of classic KS. Another 10 healthy subjects of the Uygur ethnic group were included in the normal control group. KS tissues were subjected to hematoxylin and eosin staining and immunohistochemical staining. To measure the expression of mRNA, reverse-transcription quantitative polymerase chain reaction was performed. To determine protein expression, western blot analysis was employed. AIDS-KS was mainly distributed in the face and limbs, while classic KS was mainly distributed in the limbs. The histopathological characteristics of AIDS-KS and classic KS tissues were different from those of normal tissues. TLR4 was mainly distributed in the dermis of KS tissues. The mRNA expression levels of TLR4 were reduced in classic KS and AIDS-KS. The protein expression levels of RAS, RAF, nuclear factor (NF)-κB P65 and P50 as well as inhibitor of NF-κB-α of the TLR4 signaling pathway in AIDS-KS and KS tissues were higher than those in normal tissues. In conclusion, the expression of TLR4 gene in KS tissues was decreased, while the expression of proteins of the TLR4 signaling pathway was upregulated in KS. Downregulation of TLR4 may be associated with the occurrence and development of AIDS-KS, while its restoration may represent a novel therapeutic approach for AIDS-KS.

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