2′-Hydroxyflavanone inhibits prostate tumor growth through inactivation of AKT/STAT3 signaling and induction of cell apoptosis

STAT3 signaling in prostate cancer progression and therapy resistance: An oncogenic pathway with diverse functions

The categorization of cancers demonstrates that prostate cancer is the most common malignancy in men and it causes high death annually. Prostate cancer patients are diagnosed mainly via biomarkers such as PSA test and patients show poor prognosis. Prostate cancer cells rapidly diffuse into different parts of body and their metastasis is also a reason for death. Current therapies for prostate cancer patients include chemotherapy, surgery and radiotherapy as well as targeted therapy. The progression of prostate cancer cells is regulated by different factors that STAT3 signaling is among them. Growth factors and cytokines such as IL-6 can induce STAT3 signaling and it shows carcinogenic impact. Activation of STAT3 signaling occurs in prostate cancer and it promotes malignant behavior of tumor cells. Induction of STAT3 signaling increases glycolysis and proliferation of prostate cancer cells and prevents apoptosis. Furthermore, STAT3 signaling induces EMT mechanism in increasing cancer metastasis. Activation of STAT3 signaling stimulates drug resistance and the limitation of current works is lack of experiment related to role of STAT3 signaling in radio-resistance in prostate tumor. Calcitriol, capsazepine and β-elemonic are among the compounds capable of targeting STAT3 signaling and its inhibition in prostate cancer therapy. In addition to natural products, small molecules targeting STAT3 signaling have been developed in prostate cancer therapy.

MUC15 loss facilitates epithelial-mesenchymal transition and cancer stemness for prostate cancer metastasis through GSK3β/β-catenin signaling

Patients with prostate cancer (PCa) have a high incidence of relapse and metastasis. Unfortunately, the molecular mechanisms underlying these processes have not been fully elucidated. In our study, we demonstrate that MUC15, a member of the mucin family, is a novel tumor suppressor in PCa that modulates epithelial-mesenchymal transition (EMT) and cancer stemness, contributing to PCa metastasis. First, MUC15 expression was found to be decreased in PCa tissues compared with para-carcinoma tissues. Moreover, we observed that MUC15 suppressed cell migration and invasion, both in vitro and in vivo, but had no effect on cell proliferation. Mechanistically, knockdown of MUC15 increased GSK3β phosphorylation and promoted β-catenin nuclear translocation. Therefore, the β-catenin-specific inhibitors XAV939 and PRI-724 rescued EMT in MUC15-deficient cell lines. Taken together, these results indicate that MUC15 is downregulated in PCa tissues and serves as a potential target to prevent PCa metastasis, which can inhibit EMT and cancer stemness via the GSK3β/β-catenin signaling pathway.

The subgroup of 2'-hydroxy-flavonoids: Molecular diversity, mechanism of action, and anticancer properties

Flavonoids are abundant in nature, structurally very diversified and largely investigated. However, the subgroup of 2'-hydroxyflavonoids is much less known and not frequently studied. The present review identifies the major naturally-occurring and synthetic 2'-hydroxyflavonoid derivatives and discusses their structural characteristics and biological properties, with a focus on anticancer activities. The pharmacological properties of 2'-hydroxyflavone (2'-HF) and 2'-hydroxyflavanone (2'-HFa) are detailed. Upon binding to the Ral-interacting protein Rlip implicated in the transport of glutathione conjugates, 2'-HFa inhibits tumor cell proliferation and restrict tumor growth, in particular in breast cancer models. Among the synthetic derivatives, the characteristics of the anticancer product 2D08 (2',3',4'-trihydroxy flavone) are detailed to shed light on the molecular mechanism of action of this compound, as a regulator of protein SUMOylation. Inhibition of protein SUMOylation by 2D08 blocks cancer cell migration and invasion, and the compound greatly enhances the anticancer effects of conventional cytotoxic drugs like etoposide. The structural role of the 2'-hydroxyl group on the phenyl C-ring of the flavonoid is discussed, notably the capacity to engage intramolecular H-bonding interactions with the O1 atom on the B-ring of the chromone unit (or the oxygen of a 3-OH group when it is presents). The 2'-hydroxyl group of flavonoid appears as a regulator of the conformational freedom between the bicyclic A-B unit and the appended phenyl C-ring, favoring the planarity of the molecule. It is an essential group accounting for the biological properties of 2'-HF, 2'-HFa and structurally related compounds. This review shed light on 2'-hydroxyflavonoids to encourage their use and chemical development.

2'-Hydroxyflavanone prevents LPS-induced inflammatory response and cytotoxicity in murine macrophages

2'-Hydroxyflavanone (2-HF) is a natural flavonoid isolated from citrus fruits. Multiple studies have demonstrated that 2-HF with its anti-proliferative and pro-apoptotic effects prevent the growth of various cancers. Although 2-HF is a well known anti-oxidative and chemopreventive agent, its role as an anti-inflammatory agent is not well established. In this study, we examined the effect of 2-HF on LPS-induced cytotoxicity and inflammatory response in murine RAW 264.7 macrophages. Flow cytometry analysis showed that pre-treatment of RAW 264.7 macrophages with 2-HF significantly prevented LPS-induced macrophage apoptosis. 2-HF also prevented LPS-induced reactive oxygen species (ROS) and nitric oxide (NO) production, lipid peroxidation, and loss of mitochondrial membrane potential in murine macrophages. Most importantly, the release of multiple inflammatory cytokines and chemokines such as eotaxin, IL-2, IL-10, IL-12p40, LIX, IL-15, IL-17, MCP-1, and TNF-α induced by LPS in the macrophages was inhibited by 2-HF. 2-HF also prevented LPS-induced activation of protein kinases p38MAPK and SAPK/JNK. Apart from this, LPS-induced phosphorylation, nuclear translocation, and DNA-binding of the redox transcription factor, NF-κB, was prevented by 2-HF. Our results demonstrate that 2-HF by regulating ROS/MAPK/NF-κB prevents LPS-induced inflammatory response and cytotoxicity in murine macrophages suggesting that the need of potential development of 2-HF as an anti-inflammatory agent to ameliorate various inflammatory complications.

Resveratrol inhibits the malignant progression of hepatocellular carcinoma via MARCH1-induced regulation of PTEN/AKT signaling

Resveratrol is a common, naturally occurring polyphenol confirmed with inhibited the cellular effects of carcinogenesis. However, the molecular mechanism underlying resveratrol’s action against hepatocellular carcinoma (HCC) is still unclear. In addition, MARCH1 promotes the initiation and progression of HCC, but it is unclear whether resveratrol exerts antitumor efforts by regulating MARCH1 expression. This study determined the molecular mechanisms underlying the antitumor effects of resveratrol in HCC. Resveratrol induced apoptosis and inhibited the proliferation, migration, and invasion of HCC cell lines (HepG2 and Hep3B). In addition, it inhibited MARCH1 and phospho–protein kinase B (p-AKT) expression but upregulated the phosphatase and tensin homolog deleted on chromosome 10 (PTEN) dose-dependently both in vitro and in vivo. MARCH1 knockdown by small interfering RNA (siRNA) also increased PTEN expression. Meanwhile, MK2206 (an AKT inhibitor) and bisperoxovanadium (BPV; a PTEN inhibitor) combined with resveratrol decreased MARCH1 expression more than the single-treatment HCC group. These results suggested that resveratrol affects the biological characteristics of HCC via downregulation of MARCH1 expression.

MUC15 inhibits cancer metastasis via PI3K/AKT signaling in renal cell carcinoma

Patients with renal cell carcinoma (RCC) often develop distant metastasis and the specific molecular mechanism remains poorly understood. In our study, we demonstrated that MUC15, a subtype of mucins family, could suppress the progression of RCC by inhibiting PI3K/AKT signaling. Firstly, we observed that MUC15 was notably decreased in RCC compared to normal tissue. Furthermore, we showed that MUC15 could negatively modulate the migration and invasion of RCC in vitro and in vivo. Mechanistically, we found that knocking-down of MUC15 could active the PI3K/AKT signaling by increasing the AKT phosphorylation and subsequently increase the mRNA and protein expression of MMP2 and MMP9. Interruption of the AKT pathway with the specific inhibitor LY294002 could reverse the expression of MMPs. Therefore, our study clarify the novel function of MUC15 in RCC, which may provide a new sight to diagnose and prevent RCC metastasis.

2'-Hydroxyflavanone inhibits the progression of pancreatic cancer cells and sensitizes the chemosensitivity of EGFR inhibitors via repressing STAT3 signaling

Pancreatic ductal adenocarcinoma (PDAC) is one of the most lethal malignancies, and chemotherapy is still an important treatment. It is urgent to develop new medicines because of the limitation and side effects of chemotherapy. 2'-Hydroxyflavanone (2HF) is a citrus-bioflavonoid that is considered to have anti-cancer efficacy. Compared to human pancreatic ductal epithelial cells hTERT-HPNE, more significant growth-inhibitory effects were seen in PDAC cells BxPC-3 and MIA PaCa-2. We showed that apoptosis was induced and that the cell cycle was arrested when cells were treated with 2HF. The expression of the molecular proteins cleaved PARP, cleaved Caspase3, Bax, Bcl-2, CyclinD1, and p27 changed correspondingly. Also, we observed anti-metastatic effects and changes in MMP9, E-cadherin, N-cadherin and Vimentin when cells were treated with a low dose of 2HF. Suppression of STAT3 and EGFR phosphorylation was also identified as a result of treatment with a combination of 2HF and EGFR inhibitors. The in vivo antitumor effects in KPC mice were consistent with those observed in vitro. 2HF has impactful anti-cancer efficacy and sensitizes human pancreatic cancer cells to EGFR inhibitors through the inhibition of STAT3.

Position Impact of Hydroxy Groups on Spectral, Acid-Base Profiles and DNA Interactions of Several Monohydroxy Flavanones

Structure-related biological activities of flavanones are still considered largely unexplored. Since they exhibit various medicinal activities, it is intriguing to enter deeper into their chemical structures, electronic transitions or interactions with some biomolecules in order to find properties that allow us to better understand their effects. Little information is available on biological activity of flavanone and its monohydroxy derivatives in relation to their physicochemical properties as spectral profiles, existence of protonated/deprotonated species under pH changes or interaction with Calf Thymus DNA. We devoted this work to research demonstrating differences in the physicochemical properties of the four flavanones: flavanone, 2′-hydroxyflavanone, 6-hydroxyflavanone and 7-hydroxyflavanone and linking them to their biological activity. Potentiometric titration, UV–Vis spectroscopy were used to investigate influence of pH on acid–base and spectral profiles and to propose the mode of interaction with DNA. Cyclic voltammetry was applied to evaluate antioxidant potentiality and additionally, theoretical DFT(B3LYP) method to disclose electronic structure and properties of the compounds. Molecular geometries, proton affinities and pK_a values have been determined. According to computational and cyclic voltammetry results we could predict higher antioxidant activity of 6-hydroxyflavanone with respect to other compounds. The values of K_b intrinsic binding constants of the flavanones indicated weak interactions with DNA. Structure–activity relationships observed for antioxidant activity and DNA interactions suggest that 6-hydroxyflavanone can protect DNA against oxidative damage most effectively than flavanone, 2′-hydroxyflavanone or 7-hydroxyflavanone.

Nobiletin Inhibits Cell Viability via the SRC/AKT/STAT3/YY1AP1 Pathway in Human Renal Carcinoma Cells

Nobiletin is a polymethoxy flavonoid isolated from Citrus depressa and Citrus reticulata. It has been reported that nobiletin can suppress tumors. We primarily explored the antitumor effects of nobiletin and the associated potential mechanisms in ACHN and Caki-2 renal carcinoma cells. A CCK-8 assay and cloning experiments were used to assess cell viability, and a transwell assay and scratch test were used to assess metastatic ability. The cell cycle was analyzed by flow cytometry, whereas apoptosis was analyzed using flow cytometry and a terminal dexynucleotidyl transferase (TdT)-mediated dUTP nick end labeling (TUNEL) assay. Protein expression was examined by Western blot and immunofluorescence. Renal cancer cells were subcutaneously transplanted into nude mice for in vivo studies. The data showed that nobiletin administration significantly dose- and time-dependently suppressed renal cancer cell proliferation; moreover, nobiletin treatment induced cell cycle arrest in the G0/G1 phase and promoted apoptosis. Immunofluorescence analysis indicated that nobiletin decreased the nuclear localization of signal transducer and activator of transcription 3 (STAT3) and YY1-associated protein 1 (YY1AP1). Western blot showed that the levels of phosphorylated SRC, phosphorylated AKT serine/threonine kinase (AKT), and phosphorylated STAT3 were decreased, whereas that of phosphorylated YY1AP1 was increased. The results further showed that application of insulin-like growth factor 1 (IGF1) was able to reverse the nobiletin-induced changes in the levels of phosphorylated AKT, phosphorylated STAT3, and phosphorylated YY1AP1, and could also reverse the antitumor effects of nobiletin. The results of in vivo experiments showed that, compared to the control, tumor volume and weight were both reduced following nobiletin treatment. In conclusion, our study demonstrated that nobiletin can inhibit renal carcinoma cell viability and provides a novel therapeutic approach for the treatment of kidney cancer.

RLIP inhibition suppresses breast-to-lung metastasis

Breast tumor metastasis is a leading cause of cancer-related deaths worldwide. Breast cancer (BC) cells frequently metastasize to the lungs, where they pose a formidable therapeutic challenge. In the current study, we evaluated the anti-proliferative and anti-metastatic effects of 2'-hydroxyflavanone (2HF) and RLIP inhibition in an array of triple-negative BC cell lines and an orthotopic mouse model of breast-to-lung metastasis. Compared to control treatment, RLIP inhibition reduced in-vitro cell viability and suppressed the migratory and invasive potential of BC cells. In-vitro studies showed that 2HF treatment reduced the expression of RLIP, KRAS, pERK, pSTAT3, and pP70S6K. Further, mice orthotopically implanted with lung-seeking luciferase-expressing TMD231 cells were treated with 2HF (50 mg/kg, b.w.), RLIP antisense (RAS; 5 mg/kg, b.w.), RLIP antibody (Rab; 5 mg/kg, b.w.) or a combination of 2HF + RAS + Rab. 2HF-, RAS-, and Rab-treated mice exhibited significantly lower primary tumor weight and reduced lung metastasis compared to control mice. Mice treated with a combination of 2HF + RAS + Rab exhibited no metastasis and significantly lower tumor weight than the single agent-treated mice. Collectively, our results suggest that 2HF has potential to be combined with RLIP inhibition/depletion to more effectively suppress primary breast tumor growth and metastasis to the lungs.

2'-Hydroxyflavanone inhibits in vitro and in vivo growth of breast cancer cells by targeting RLIP76

Consumption of citrus-fruits is associated with reduced incidence of breast cancer (BC), the most common cancer diagnosed in women across the globe. In this study, we investigated the anticancer potential of 2-Hydroxyflavanone (2HF) in BC. 2HF, a citrus-bioflavonoid, has demonstrated anticancer properties in various cancers, but its anticancer role in BC has not been well studied. We investigated the in vitro and in vivo growth inhibitory effects of 2HF in an array of BC lines and in xenograft mouse models of ER-positive and HER2-positive BC cells. Compared to control, 2HF treatment reduced cell viability and suppressed migratory and invasive potential of BC cells, while, no growth inhibitory effects were observed in non-tumorigenic breast epithelial cells. Further, 2HF inhibited the expression of RLIP76, a stress-defensive and anti-apoptotic protein, which is over-expressed in BC cells and simultaneously reduced proliferation of BC cells. Nude mice bearing MCF7 or SKBR3 BC cells xenografts treated with either 2HF or targeting RLIP76 by RLIP76-antisense or RLIP76-antibody treatment had significantly lower tumor-weight as compared to corresponding controls. In addition, Western-blotting and immunohistochemical analysis of tumor tissue from control and treatment group mice showed that 2HF decreased protein expression levels of RLIP76, and the decrease was similar to those seen following RLIP76-antisense treatment. Furthermore, 2HF decreased expression of Ki67, CD31, vimentin, inhibited phosphorylation of Akt and expression of survivin and Bcl2, and increased levels of Bax, E-cadherin, and cleaved-PARP. Therefore, our results indicate that 2HF may suppress BC growth in vitro and in vivo by targeting RLIP76, and may serve as a potential adjuvant treatment in BC patients.

Metastasis of breast tumor cells to brain is suppressed by targeting RLIP alone and in combination with 2'-Hydroxyflavanone

Brain metastasis is an important cause of morbidity and mortality in cancer-patients. Breast tumor cells frequently metastasize to brain and initiate severe therapeutic complications. In the present study, we evaluated the anti-metastatic effects of 2'-hydroxyflavanone (2HF) alone and in combination with RLIP targeted therapy in a novel murine model of breast tumor metastasis. The MDA-MB231Br (brain-seeking) breast cancer (BC) cells stably-transfected with luciferase were injected into the left-ventricle of NSG mouse heart and the migration of cells to brain was monitored using a non-invasive bioluminescent imaging system. To evaluate the tumor growth suppressive effects, mice were given 2HF (50 mg/kg, b.w., alternate days orally), RLIP-antibody (Rab; 5 mg/kg, b.w., weekly i.p.) or combination of 2HF+Rab starting day1 after intra-cardiac injection. Our results reveal that 2HF and Rab significantly prevented the metastasis of BC cells to brain. Further, mice treated with combination of 2HF+Rab exhibited no metastasis as compared to either or the single agent-treated mice. This study for the first time demonstrates the anti-metastatic effects of 2HF and RLIP-inhibition in-vivo in a novel breast tumor metastasis model and provides the rationale for further clinical investigation.

The α' subunit of β-conglycinin and various glycinin subunits of soy are not required to modulate hepatic lipid metabolism in rats

PURPOSE

This study examined the effect of soy proteins with depletion of different subunits of the two major storage proteins, β-conglycinin and glycinin, on hepatic lipids and proteins involved in lipid metabolism in rats, since the bioactive component of soy responsible for lipid-lowering is unclear.

METHODS

Weanling Sprague Dawley rats were fed diets containing either 20% casein protein in the absence (casein) or presence (casein + ISF) of isoflavones or 20% alcohol-washed soy protein isolate (SPI) or 20% soy protein concentrates derived from a conventional (Haro) or 2 soybean lines lacking the α' subunit of β-conglycinin and the A1-3 (1TF) or A1-5 (1a) subunits of glycinin. After 8 weeks, the rats were necropsied and liver proteins and lipids were extracted and analysed.

RESULTS

The results showed that soy protein diets reduced lipid droplet accumulation and content in the liver compared to casein diets. The soy protein diets also decreased the level of hepatic mature SREBP-1 and FAS in males, with significant decreases in diets 1TF and 1a compared to the casein diets. The effect of the soy protein diets on female hepatic mature SREBP-1, FAS, and HMGCR was confounded since casein + ISF decreased these levels compared to casein alone perhaps muting the decrease by soy protein. A reduction in both phosphorylated and total STAT3 in female livers by ISF may account for the gender difference in mechanism in the regulation and protein expression of the lipid modulators.

CONCLUSIONS

Overall, soy protein deficient in the α' subunit of β-conglycinin and A1-5 subunits of glycinin maintain similar hypolipidemic function compared to the conventional soy protein. The exact bioactive component(s) warrant identification.

Synergistic Effects of Dietary Natural Products as Anti-Prostate Cancer Agents

This review is to describe synergistic effects of various combinations of dietary natural products including curcumin, quercetin, soybean isoflavones, silibinin, and EGCG that have potential for the treatment of prostate cancer. These data can provide valuable insights into the future rational design and development of synergistic and/or hybrid agents for potential treatment of prostate cancer.