Guardian Molecule PROX1 Slows Liver Cancer, New Streptomyces Strain HUAS MG91T Isolated

Researchers from the German Cancer Research Center (DKFZ), the Hector Institute für Translational Brain Research (HITBR), and the European Molecular Biology Laboratory (EMBL) discovered that a "guardian molecule" ensures liver cells maintain their identity. This finding is significant for cancer medicine, as altered cell identity is a key principle of carcinogenesis. The Heidelberg researchers demonstrated that this sentinel, PROX1 (Prospero homeobox protein 1), can slow down potent cancer drivers and cause malignant liver tumors to regress in mice. Molecular biologist Moritz Mall of the DKFZ notes the importance of plasticity in cancer and his team's goal to reduce it. Judith Zaugg from EMBL explains that they "developed a computer program to screen candidates for the essential properties that a guardian molecule must possess" and identified PROX1. "It turned out that PROX1 is a very influential guard in liver cells," says Moritz Mall. "If it is missing, the liver cells change their phenotype." Furthermore, researchers found that PROX1 must be constantly active. Increasing PROX1 activity locally in the liver could be a novel approach to liver cancer prevention and treatment. Separately, strain HUAS MG91T, classified within the genus Streptomyces, was isolated from the rhizosphere of Nicotiana tabacum L. (tobacco) in Changde City, Hunan Province, China. Genomic DNA was prepared from cells grown on Gause's synthetic No.1 medium for 7 days at 28 °C. The strain is Gram-positive, with well-developed aerial and substrate mycelium. Spores are short, rod-shaped with smooth surfaces and Rectiflexibles spore chains. Diffusible pigment was observed on Gause's synthetic No.1 medium, ISP 2-7 media, and R2A medium. It grows at temperatures between 15 and 35 °C, optimally at 28 °C, and at pH 6.0-11.0. The strain tolerates up to 6.0% NaCl. Strain HUAS MG91 contained ll-diaminopimelic acid. The menaquinones were MK-9(H) (38.9%), MK-9(H) (25.6%), MK-9(H) (20.7%) and MK-9(H) (14.1%). The DNA G + C content of the genome sequence, consisting of 8,451,342 bp, is 71.6%. AntiSMASH analyses revealed the presence of terpene, RiPP-like, T3PKS, T1PKS, NRPS, NI-siderophore, NAPAA, and lanthipeptide-class-I. The type strain is HUAS MG91 (=MCCC 1K09288 = JCM 37027 ). The GenBank/EMBL/DDBJ accession numbers for the 16S rRNA gene sequence and genome sequence are PQ097303 and CP159534.1, respectively.