Luteolin and its analog luteolin-7-methylether from Leonurus japonicus Houtt suppress aromatase-mediated estrogen biosynthesis to alleviate polycystic ovary syndrome by the inhibition of tumor progression locus 2.

ETHNOPHARMACOLOGICAL RELEVANCE: Leonurus japonicus Houtt (L. japonicus, Chinese motherwort), known as Yi Mu Cao which means "good for women", has long been widely used in China and other Asian countries to alleviate gynecological disorders, often characterized by estrogen dysregulation. It has been used for the treatment of polycystic ovary syndrome (PCOS), a common endocrine disorder in women but the underlying mechanism remains unknown. AIM OF THE STUDY: The present study was designed to investigate the effect and mechanism of flavonoid luteolin and its analog luteolin-7-methylether contained in L. japonicus on aromatase, a rate-limiting enzyme that catalyzes the conversion of androgens to estrogens and a drug target to induce ovulation in PCOS patients. MATERIALS AND METHODS: Estrogen biosynthesis in human ovarian granulosa cells was examined using ELISA. Western blots were used to explore the signaling pathways in the regulation of aromatase expression. Transcriptomic analysis was conducted to elucidate the potential mechanisms of action of compounds. Finally, animal models were used to assess the therapeutic potential of these compounds in PCOS. RESULTS: Luteolin potently inhibited estrogen biosynthesis in human ovarian granulosa cells stimulated by follicle-stimulating hormone. This effect was achieved by decreasing cAMP response element-binding protein (CREB)-mediated expression of aromatase. Mechanistically, luteolin and luteolin-7-methylether targeted tumor progression locus 2 (TPL2) to suppress mitogen-activated protein kinase 3/6 (MKK3/6)-p38 MAPK-CREB pathway signaling. Transcriptional analysis showed that these compounds regulated the expression of different genes, with the MAPK signaling pathway being the most significantly affected. Furthermore, luteolin and luteolin-7-methylether effectively alleviated the symptoms of PCOS in mice. CONCLUSIONS: This study demonstrates a previously unrecognized role of TPL2 in estrogen biosynthesis and suggests that luteolin and luteolin-7-methylether have potential as novel therapeutic agents for the treatment of PCOS. The results provide a foundation for further development of these compounds as effective and safe therapies for women with PCOS.

Hexachlorophene, a selective SHP2 inhibitor, suppresses proliferation and metastasis of KRAS-mutant NSCLC cells by inhibiting RAS/MEK/ERK and PI3K/AKT signaling pathways.

Kirsten rat sarcoma viral oncogene homolog (KRAS) mutations account for 35% of the genetic alterations in non-small cell lung cancer (NSCLC). The Src-homology region 2-containing protein tyrosine phosphatase 2 (SHP2), encoded by PTPN11, is closely involved in RAS downstream pathways and development of many tumors by affecting cell proliferation, differentiation, and immunity. Targeting SHP2 with small molecules may be a promising avenue for the treatment of KRAS-mutant (mut) NSCLC. Herein, hexachlorophene (HCP) was identified as a SHP2 inhibitor with an IC50 value of 5.63 ± 0.75 µM through screening of the FDA-approved drug library. HCP specifically inhibited SHP2 rather than other phosphatases. Molecular docking showed that HCP displayed an orientation favorable for nucleophilic attack in the catalytic domain of SHP2. HCP suppressed viability of multiple KRAS-mut and KRAS-wild type cells and induced senescence and apoptosis in KRAS-mut cells. Moreover, HCP reversed epithelial-mesenchymal transition to suppress metastasis in KRAS-mut cells, and inhibited the RAS/MEK/ERK and PI3K/AKT signaling pathways by suppression of SHP2 phosphorylation and formation SHP2/Grb2/Gab1/SOS1 complex. In summary, HCP can act as a specific SHP2 inhibitor to inhibit KRAS-mut NSCLC cell proliferation and metastasis and induce senescence through suppression of the RAF/MEK/ERK and PI3K/AKT pathways. HCP warrants further investigation as a new compound skeleton for the development of selective SHP2 inhibitors for the treatment of NSCLC.

Anticancer activity of dietary xanthone α-mangostin against hepatocellular carcinoma by inhibition of STAT3 signaling via stabilization of SHP1.

Hepatocellular carcinoma (HCC) is one of the most lethal human cancers worldwide. The dietary xanthone α-mangostin (α-MGT) exhibits potent anti-tumor effects in vitro and in vivo. However, the anti-HCC effects of α-MGT and their underlying mechanisms are still vague. Aberrant activation of signal transducer and activator of transcription 3 (STAT3) is involved in the progression of HCC. We therefore investigated whether α-MGT inhibited the activation of STAT3 and thereby exhibits its anti-HCC effects. In this study, we found that α-MGT significantly suppressed cell proliferation, induced cell cycle arrest, and triggered apoptosis in HCC cells, including HepG2, SK-Hep-1, Huh7, and SMMC-7721 cells in vitro, as well as inhibiting tumor growth in nude mice bearing HepG2 or SK-Hep-1 xenografts. Furthermore, α-MGT potently inhibited the constitutive and inducible activation of STAT3 in HCC cells. In addition, α-MGT also suppressed IL-6-induced dimerization and nuclear translocation of STAT3, which led to inhibition of the expression of STAT3-regulated genes at both mRNA and protein levels. Mechanistically, α-MGT exhibited effective inhibition of the activation of STAT3's upstream kinases, including JAK2, Src, ERK, and Akt. Importantly, α-MGT increased the protein level of Src homology region 2 domain-containing phosphatase-1 (SHP1), which is a key negative regulator of the STAT3 signaling pathway. Furthermore, α-MGT enhanced the stabilization of SHP1 by inhibiting its degradation mediated by the ubiquitin-proteasome pathway. Knockdown of SHP1 using siRNA obviously prevented the α-MGT-mediated inhibition of the activation of STAT3 and proliferation of HCC cells. In summary, α-MGT exhibited a potent anti-HCC effect by blocking the STAT3 signaling pathway via the suppression of the degradation of SHP1 induced by the ubiquitin-proteasome pathway. These findings also suggested the potential of dietary derived α-MGT in HCC therapy.

Cytotoxic Lignans and Sesquiterpenoids from the Rhizomes of Acorus tatarinowii.

Five new compounds, including a rare phenyldihydronaphthalene lignanamide (1), an unusual hybrid-norlignan derivative (2), a rare cycloheptenone oxide derivative (3), one new acorane-type sesquiterpenoid (4), and one new guaiane-type sesquiterpenoid (5), together with seven known compounds (6-12), have been isolated from the rhizomes of Acorus tatarinowii. The structures of compounds 1-5 were determined by means of extensive spectroscopic methods. To the best of our knowledge, this is first report of a phenyldihydronaphthalene lignanamide and hybrid-norlignan and cycloheptenone oxide derivatives from the genus Acorus. In addition, compound 5 represents the first guaiane-type sesquiterpenoid with an epoxy group located between C-6 and C-9 from natural sources. Compounds 1-12 were evaluated for their in vitro cytotoxicity against five tumor cell lines. Among them, 2, 3, 5, and 10 exhibited moderate cytotoxicity with IC50 values of 2.11-9.23 µM.

An unusual dihydrobenzofuroisocoumarin and ent-kaurane diterpenoids from Pteris multifida.

An unusual 5-C-methylated-dihydrobenzofuroisocoumarin, named multifidarin A (1), and two new ent-kaurane diterpenoids, named multikauranes A (2) and B (3), together with three known ent-kaurane diterpenoids, were isolated from the whole plants of Pteris multifida. The structures of 1-3 were elucidated by spectroscopic methods. The cytotoxic activities of all new compounds were evaluated against five human tumor cell lines. A possible biosynthetic process for the formation of 1 is proposed.

Cytotoxic taccalonolides and withanolides from Tacca chantrieri.

Six new taccalonolides, taccalonolides AT-AY (1-6), and two new withanolides, chantriolides D and E (7 and 8), together with ten known compounds (9-18), have been isolated from whole plants of Tacca chantrieri. The structures, including the absolute configurations of some of the compounds, were determined by spectroscopic and chemical methods. All compounds were evaluated for their in vitro cytotoxicity against five tumor cell lines. Compounds 9, 10, 13-15, and 17 exhibited cytotoxic activity, with IC50 values of 1.13-5.71 µM, while compound 7 showed selective cytotoxicity. The results indicated that taccalonolides with a six-membered lactone moiety located at C-15 and C-24 were devoid of cytotoxicity against five tumor cell lines (> 10 µM).