Sprouty4 mRNA variants and protein expressions in breast and lung-derived cells

Abstract

Ab st rac t . Sp rout y p rot ei ns a r e mo du lat or s of mitogen-induced signalling processes and are therefore hypothesized to affect malignant diseases. As a member of the Sprouty family, Sprouty4 has been previously shown to function as a tumour suppressor in lung and breast cancer. The present study analysed the expression of two known Sprouty4 splice variants in cells established from malignant and normal lung and breast tissues using semi-quantitative reverse transcription-polymerase chain reaction and immunoblotting. The results indicated that the expression of the two messenger RNA (mRNA) variants was reduced in the cells derived from malignant tissue in comparison to the normal counterparts. Although the expression of the two splice variants were associated in both tissue types, on average, the relative expression of the longer variant was slightly increased in malignant cells compared with normal tissues. Notably, the protein levels reflected the expression observed at the mRNA level only in breast-derived cells. Contrarily, with regards to the measured mRNA levels, Sprouty4 protein was disproportional augmented in lung cells known to harbour the mutated K-Ras gene. IntroductionThe alteration of important molecules involved in signal transduction is a common characteristic of all malignant cells (1). The mitogen activated protein kinase (MAPK) pathway, which is crucially involved in balancing cell death and differentiation on one side and proliferation and migration on the other, is one of the best described signalling routes that is deregulated in cancer (2). Due to the vital role of the MAPK pathway, numerous feedback loops are present to allow a fine-tuning of signal intensity and duration (3). Certain molecules acting in such a regulatory loop are the members of the Sprouty (Spry) protein family. First discovered in Drosophila (4,5), the Spry proteins counteract processes induced by the presence of various growth factors. In humans, 4 Spry family members are known; all of which share a conserved Spry domain at the C-terminus and 2 homolog N-terminal boxes (6). As indicated by knockout studies in mice, the functions of Sprouty proteins overlap but are not redundant (7-10). Although Spry1, Spry2 and Spry4 can be detected in all organs, their expression pattern in the various cell types is clearly distinguishable (11). Like in Drosophila, mammalian Spry proteins interfere with signal transduction, particularly in the MAPK pathway, in response to various mitogens, such as the members of the fibroblast growth factors (6). In contrast to Drosophila, in mammalian systems, signalling activated by epidermal growth factor is increased with augmented Spry expression. Therefore, the Spry proteins in humans are generally considered as modulators of signal transduction (12). Accordingly, dependent on the tumour type, Spry proteins are found to fulfil multiple roles in cancer. For example, Spry2 has been indicated to function as an oncogene in colon cancer (13,14) and Spry1 has a tumour promoting role in rhabd...

Sprouty3 and Sprouty4, Two Members of a Family Known to Inhibit FGF-Mediated Signaling, Exert Opposing Roles on Proliferation and Migration of Glioblastoma-Derived Cells

“…Indeed, in several of the GBMs analyzed we were unable to detect this Spry isoform. Similarly, in lung [14,38] and breast cancer [39], a repression of Spry4 is coinciding with a postulated tumor-suppressive function. With regard to Spry3, in normal brain tissue its expression is well documented, but due to its low abundance in other tissues, expression data in cancers are rarely available [6,7].…”

Role of SPRY4 in health and disease

“…Compared to normal human mammary epithelial cells (nHMEC), SPRY4 protein and mRNA expression were reduced in other breast cancer cell lines (BT20, MCF7, SKBR3, MDA-MB468, ZR-75), except for the MDA-MB231 cell line ( 36 , 88 , 89 ). Vanita Vanas et al.…”