Expression and intracellular localization of Smad proteins in human endometrial cancer

The aim of our study was to examine expression of Smad proteins i.e., Smad2, Smad3 and Smad4 both as mRNA and protein as well as their intracellular localization in normal (n=13) and neoplastic (n=42) endometrial tissue specimens using RT-PCR and immunological techniques i.e., Western blot and ELISA. Two uncommon female genital tract tumours, rhabdomyosarcoma of uterine of the cervix and uterine carcinosarcoma were also included. No statistically significant differences were found in the mRNA level of the examined Smad proteins between normal and tumour tissue specimens. Smad2 and Smad3 mRNAs were detected both in uterine carcinosarcoma and rhabdomyosarcoma of the uterine cervix. However, significantly lower Smad2 and Smad4 mRNA level was noted when the depth of myometrial invasion was considered (p<0.05). In endometrial cancer as compared to normal endometrium significantly higher levels of Smad2 and Smad3 proteins, both in cytoplasmic (p=0.002; p=0.0001) and nuclear (p=0.016; p=0.0004) fractions were observed. Both in uterine carcinosarcoma and rhabdomyosarcoma of the uterine cervix Smad2, Smad3 and Smad4 proteins were not detected. Moreover, significantly elevated Smad4 protein level in cytoplasmic fraction was stated when tumour grade and depth of myometrial invasion was undertaken (p<0.05). When intracellular distribution of Smads was considered differences between cytoplasmic and nuclear localization in normal and carcinomatous endometrium was stated. In endometrial cancer decreased number of cases with Smad3 and increased number of cases with Smad4 located in nuclear fraction was found. In conclusion, the disturbances in Smad protein expression and/or differences in their intracellular distribution suggest, that TGF-beta signaling pathway via Smads may be deregulated in endometrial carcinomas

TGF-beta signaling is disrupted in endometrioid-type endometrial carcinomas

OBJECTIVE: Previous studies have demonstrated deregulation of the expression and changes in the intracellular distribution of TGF-beta pathway components in human endometrial cancer (EC). The aim of this study was to assess the relationship between the expression of TGF-beta cascade components, including TGF-beta receptor type I (TGF beta RI) and type II (TGF beta RII), SMAD2, SMAD3, SMAD4, and clinicopathological features--tumor grade, FIGO classification, and depth of myometrial invasion--of type I (endometrioid-type) ECs to give some insight into the role of TGF-beta cascade components in endometrial tumorigenesis. METHODS: The expression of TGF beta RI, TGF beta RII, SMAD2, SMAD3, and SMAD4 was evaluated both at the mRNA and protein level using reverse transcription polymerase chain reaction (RT-PCR) and ELISA, respectively. RESULTS: Infiltrating endometrial carcinomas (less and more than half of the myometrial wall thickness) express significantly higher TGF beta RII protein level compared with non-infiltrating tumors (P = 0.04 and P = 0.01, respectively). Decreased level of SMAD2 and SMAD4 mRNAs was observed in the uterine tumors infiltrating less and more than half of the myometrial wall (P = 0.03 and P = 0.02, respectively) compared with noninfiltrating ECs. Significantly higher SMAD4 protein level in the cytoplasmic fraction of ECs was found when tumor grade and depth of myometrial invasion were considered (P < 0.05). Generally, tumor progression was associated with a decreased number of cases characterized by the presence of SMADs in the nuclear fraction only. CONCLUSION: Our data suggest that disturbances of the TGF beta RII and SMAD4 expression as well as localization of SMADs may be important to the infiltration of the myometrial wall by the type I endometrial carcinomas