Background: The hedgehog (HH) signaling pathway is a key regulator of embryonic patterning, tissue regeneration, stem cell renewal, and cancer growth. The smoothened (SMO) protein regulates the HH signaling pathway and has demonstrated oncogenic activity. Methods: To clarify the role of the HH signaling pathway in tumorigenesis, the expression profile of key HH signaling molecules, including SMO, PTCH1, GLI1, GLI2, and GLI3, were determined in thirty-three cancer cell lines. We performed a computational analysis of the upstream region of the SMO gene to identify the regulatory elements. Results: Three potential CpG islands and several putative SMO promoter elements were identified. Luciferase reporter assays mapped key SMO promoter elements, and functional binding sites for SP1, AP1, CREB, and AP-2a transcription factors in the core SMO promoter region were confirmed. A hypermethylated SMO promoter was identified in several cancer cell lines suggesting an important role for epigenetic silencing of SMO expression in certain cancer cells. Discussion: These results have important implications for our understanding of regulatory mechanisms controlling HH pathway activity and the molecular basis of SMO gene function. Moreover, this study may prove valuable for future research aimed at producing therapeutic downregulation of SMO expression in cancer cells.

Alternative fertilizations are essential to minimize the deteriorating effects of chemical fertilizers on soil and water quality/health. Accordingly, the present work investigated the effects of combined organic-inorganic fertilization (COIF) on wheat and rice yields, soil nutrients, and soil Cd accumulation. Hence, seven different treatments were set up: control (CK); conventional fertilization (CF); optimized fertilization (OF); organic fertilizer replacing 25% (T1) and 50% (T2) of OF; and organic nitrogen (N) replacing 25% (M1) and 50% (M2) of OF-N. Overall, significant increases occurred in the yields of COIF crops. Compared with the CF, the highest wheat and rice yields happened in M1 treatment (approximately by18.5%) (P < 0.05). COIF slightly alleviated soil acidification, and improved the cation exchange capacity (CEC) of the study soils. Besides, COIF treatments significantly increased the contents of total phosphorus, total potassium, available phosphorus, and available potassium by 6.35 to 16.9 %, 3.17 to 10.9 %, 5.53 to 28.7 %, and 2.6 to 12 %, respectively (P <0.05). Nevertheless, negligible increases took place in Cd content of COIF soils compared with the CK. Altogether, our results concluded on 25% replacement of OF-N by organic N (M1) to effectively improve the fertility/ecological sustainability of the study soils.