N-myc downstream-regulated gene 1 (NDRG1) has been proposed as a tumor suppressor gene in many different types of tumors, but its potential function and corresponding mechanism are not yet fully elucidated. This study aims to detect the possible function of NDRG1 in gastric cancer progression. In this study, 112 paired gastric cancer tissues and corresponding nonmalignant gastric tissues were utilized to identify the differential protein expression of NDRG1 by immunohistochemistry and its clinical significance was analyzed. Furthermore, 49 of 112 paired gastric specimens were used to detect the differential mRNA expression by real-time PCR. The over expression of NDRG1 in human gastric cancer cell line AGS by PcDNA3.1-NDRG1 transfection was utilized to detect the role of NDRG1 in regulating the biological behavior of gastric cancer. NDRG1 expression was significantly decreased in primary gastric cancer tissues, compared with its corresponding nonmalignant gastric tissues (p < 0.05), and its decreased expression was significantly associated with lymph node metastasis (p < 0.01), invasion depth (p < 0.01) and differentiation (p < 0.05). Additionally, the overall survival rate of gastric cancer patients with high expression of NDRG1 was higher than those with low expression during the follow-up period. NDRG1 overexpression suppressed cells proliferation, invasion and induced a G1 cell cycle arrest in gastric cancer. Furthermore, the down-regulation of NDRG1 in gastric cancer metastatic progression was correlated to E-cadherin and MMP-9. Our results verify that NDRG1 acts as a tumor suppressor gene and may play an important role in the metastasis progression and prognosis of gastric cancer.
Verticillium dahliae, a destructive and soil-borne fungal pathogen, causes massive losses in cotton yields. However, the resistance mechanism to V. dahilae in cotton is still poorly understood. Accumulating evidence indicates that chitinases are crucial hydrolytic enzymes, which attack fungal pathogens by catalyzing the fungal cell wall degradation. As a large gene family, to date, the chitinase genes (Chis) have not been systematically analyzed and effectively utilized in cotton. Here, we identified 47, 49, 92, and 116 Chis from four sequenced cotton species, diploid Gossypium raimondii (D5), G. arboreum (A2), tetraploid G. hirsutum acc. TM-1 (AD1), and G. barbadense acc. 3–79 (AD2), respectively. The orthologous genes were not one-to-one correspondence in the diploid and tetraploid cotton species, implying changes in the number of Chis in different cotton species during the evolution of Gossypium. Phylogenetic classification indicated that these Chis could be classified into six groups, with distinguishable structural characteristics. The expression patterns of Chis indicated their various expressions in different organs and tissues, and in the V. dahliae response. Silencing of Chi23, Chi32, or Chi47 in cotton significantly impaired the resistance to V. dahliae, suggesting these genes might act as positive regulators in disease resistance to V. dahliae.
BackgroundSucrose synthase (SUS) is widely considered a key enzyme participating in sucrose metabolism in higher plants and regarded as a biochemical marker for sink strength in crops. However, despite significant progress in characterizing the physiological functions of the SUS gene family, knowledge of the trajectory of evolutionary processes and significance of the family in higher plants remains incomplete.ResultsIn this study, we identified over 100 SUS genes in 19 plant species and reconstructed their phylogenies, presenting a potential framework of SUS gene family evolution in higher plants. Three anciently diverged SUS gene subfamilies (SUS I, II and III) were distinguished based on their phylogenetic relationships and unique intron/exon structures in angiosperms, and they were found to have evolved independently in monocots and dicots. Each subfamily of SUS genes exhibited distinct expression patterns in a wide range of plants, implying that their functional differentiation occurred before the divergence of monocots and dicots. Furthermore, SUS III genes evolved under relaxed purifying selection in dicots and displayed narrowed expression profiles. In addition, for all three subfamilies of SUS genes, the GT-B domain was more conserved than the “regulatory” domain.ConclusionsThe present study reveals the evolution of the SUS gene family in higher plants and provides new insights into the evolutionary conservation and functional divergence of angiosperm SUS genes.
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