Tissue transglutaminase expression is necessary for adhesion, metastatic potential and cancer stemness of renal cell carcinoma.

Tissue transglutaminase (TG2) is the ubiquitously expressed member of transglutaminase family and shown to play a critical role in the development and progression of drug resistance malignancies. We have previously showed the association of TG2 upregulation with progression and metastasis of renal cell carcinoma (RCC) and low disease-free survival. In the present study we further investigate the role of TG2 in cell adhesion, migration and invasion of RCC by silencing TG2 expression in Caki-2 and A-498 primary site and Caki-1 and ACHN metastatic site RCC cell lines. Downregulation of TG2 expression led up to a 60% decrease in actin stress fiber formation and adhesion to ß 1 integrin (ITGB1) substrates fibronectin, collagen type I and laminin in both primary and metastatic site RCC cell lines. In addition, treatment with siRNAs against TG2 impaired the migration capacity and cellular invasiveness of ITGB1 substrates in all 4 RCC cell lines. Lastly, the knockdown of TG2 in metastatic Caki-1 cells diminished the expression of CD44, CD73-and CD105 cancer stem cell-like markers. We conclude, for the first time, that TG2 expression is critical for cancer cell adhesion, migration, invasiveness and cancer cell-stemness during RCC progression and dissemination. Therefore, combined targeting of TG2 with drugs widely used in the treatment of RCC may be a promising therapeutic strategy for RCC.

Sambulin A and B, non-glycosidic iridoids from Sambucus ebulus, exert significant in vitro anti-inflammatory activity in LPS-induced RAW 264.7 macrophages via inhibition of MAPKs's phosphorylation.

ETHNOPHARMACOLOGICAL RELEVANCE: The leaves of Sambucus ebulus L. (Adoxaceae) are widely used in Turkish folk medicine particularly against inflammatory disorders. The fresh leaves after wilted over fire or the poultices prepared are directly applied externally to heal burns, edema, eczema, urticarial and abscess. Two iridoids were recently isolated (sambulin A, sambulin B) from the leaves of S. ebulus. AIM OF THE STUDY: This study aims to investigate the in vitro anti-inflammatory activities of these iridoids on LPS-induced RAW 264.7 macrophages. MATERIALS AND METHODS: Raw 264.7 macrophages were treated with 12.5, 25 and 50µg/ml Sambulin A and 6.25, 12.5 and 25µg/ml Sambulin B and induced with 1µg/ml lipopolysaccaharides (LPS). Effect of the compounds on nitric oxide (NO) production and cytokines (TNFα, IL-6) were determined by Griess and ELISA assays respectively. iNOS and the phosphorylation levels of MAPKs (ERK, JNK) were examined by Western Blot. RESULTS: Sambulin A and sambulin B inhibited 52.82% and 72.88% of NO production at 50 and 25µg/ml concentrations respectively. The levels of iNOS were significantly decreased by both molecules, sambulin B at 25µg/ml almost completely decreased iNOS levels (97.53%). Both molecules significantly inhibited TNFα productions. However, only sambulin B inhibited IL-6 production. Consequently, it was shown that sambulin B exerted its effect through the inhibition of ERK and JNK phosphorylations. CONCLUSION: The prominent bioactivities exerted by two iridoids will contribute to explanation of the usage of S. ebulus in traditional medicine against rheumatoid diseases.