Targeting TAOK1 with resveratrol inhibits esophageal squamous cell carcinoma growth in vitro and in vivo.

The worldwide incidence and mortality rates of esophageal squamous cell carcinoma (ESCC) have increased over the last decade. Moreover, molecular targets that may benefit the therapeutics of patients with ESCC have not been fully characterized. Our study discovered that thousand and one amino-acid protein kinase 1 (TAOK1) is highly expressed in ESCC tumor tissues and cell lines. Knock-down of TAOK1 suppresses ESCC cell proliferation in vitro and patient-derived xenograft or cell-derived xenograft tumors growth in vivo. Moreover, TAOK1 overexpression promotes ESCC growth in vitro and in vivo. Additionally, we identified that the natural small molecular compound resveratrol binds to TAOK1 directly and diminishes the kinase activity of TAOK1. Targeting TAOK1 directly with resveratrol significantly inhibits cell proliferation, induces cell cycle arrest and apoptosis, and suppresses tumor growth in ESCC. Furthermore, the silencing of TAOK1 or the application of resveratrol attenuated the activation of TAOK1 downstream signaling effectors. Interestingly, combining resveratrol with paclitaxel, cisplatin, or 5-fluorouracil synergistically enhanced their therapeutic effects against ESCC. In conclusion, this work illustrates the underlying oncogenic function of TAOK1 and provides a theoretical basis for the application of targeting TAOK1 therapy to the clinical treatment of ESCC.

Lagerstroemia indica extract regulates human hair dermal papilla cell growth and degeneration via modulation of ß-catenin, Stat6, and TGF-ß signaling pathway.

BACKGROUND: Lagerstroemia indica (L. indica) is reported to have diverse biological activities including anti-inflammatory, anti-cancer, neuro-regulatory, antidiabetic, and antioxidant activity. AIMS: The purpose of this study is to examine the potential of hair growth promotion and/or hair loss prevention by L. indica extract. PATIENTS/METHODS: The effects of L. indica on hair growth have been studied in human hair follicle dermal papillary (hHFDP) cells and follicular organ culture ex vivo by cell proliferation assay, PCR, western blot analysis, and reporter gene activity assay. Moreover, a clinical trial was conducted in healthy volunteers. RESULTS: Lagerstroemia indica significantly promoted the proliferation of hHFDP cells, which was associated with increased expression of TCF/LEF, VEGF, and Gli1 mRNA, and inhibition of STAT6 and Smad2 mRNA. Treatment with L. indica also increased the TCF/LEF reporter gene activity but downregulated the SBE- and STAT6-luciferase activities. The expression of total ß-catenin, CDK4, and CDK2 were elevated, while that of STAT6 and SMAD2/3 was suppressed upon treatment with L. indica. In human hair follicles organ culture, L. indica significantly inhibited hair follicular degeneration. The clinical trial showed a statistically significant rise in total hair count in test group (n = 24) after 24 weeks of applying the hair tonic enriched with L. indica (141.46 ± 21.27 number/cm2 , p < 0.05). CONCLUSION: We suggest that L. indica extract prevents hair loss as well as stimulate hair growth by regulating the Wnt-ß-catenin, JAK3-STAT6, and TGF-ß1-Smad signaling pathways, and may be further developed as a novel functional cosmetic for preventing hair loss.

3-Deoxysappanchalcone Inhibits Skin Cancer Proliferation by Regulating T-Lymphokine-Activated Killer Cell-Originated Protein Kinase in vitro and in vivo.

BACKGROUND: Skin cancer is one of the most commonly diagnosed cancers worldwide. The 5-year survival rate of the most aggressive late-stage skin cancer ranges between 20 and 30%. Thus, the discovery and investigation of novel target therapeutic agents that can effectively treat skin cancer is of the utmost importance. The T-lymphokine-activated killer cell-originated protein kinase (TOPK), which belongs to the serine-threonine kinase class of the mitogen-activated protein kinase kinase (MAPKK) family, is highly expressed and activated in skin cancer. The present study investigates the role of 3-deoxysappanchalcone (3-DSC), a plant-derived functional TOPK inhibitor, in suppressing skin cancer cell growth. PURPOSE: In the context of skin cancer prevention and therapy, we clarify the effect and mechanism of 3-DSC on different types of skin cancer and solar-simulated light (SSL)-induced skin hyperplasia. METHODS: In an in vitro study, western blotting and in vitro kinase assays were utilized to determine the protein expression of TOPK and its activity, respectively. Pull-down assay with 3-DSC and TOPK (wild-type and T42A/N172 mutation) was performed to confirm the direct interaction between T42A/N172 amino acid sites of TOPK and 3-DSC. Cell proliferation and anchorage-independent cell growth assays were utilized to determine the effect of 3-DSC on cell growth. In an in vivo study, the thickness of skin and tumor size were measured in the acute SSL-induced inflammation mouse model or SK-MEL-2 cell-derived xenografts mouse model treated with 3-DSC. Immunohistochemistry analysis of tumors isolated from SK-MEL-2 cell-derived xenografts was performed to determine whether cell-based results observed upon 3-DSC treatment could be recapitulated in vivo. RESULTS: 3-DSC is able to inhibit cell proliferation in skin cancer cells in an anchorage-dependent and anchorage-independent manner by regulation of TOPK and its related signaling pathway in vitro. We also found that application of 3-DSC reduced acute SSL-induced murine skin hyperplasia. Additionally, we observed that 3-DSC decreased SK-MEL-2 cell-derived xenograft tumor growth through attenuating phosphorylation of TOPK and its downstream effectors including ERK, RSK, and c-Jun. CONCLUSIONS: Our results suggest that 3-DSC may function in a chemopreventive and chemotherapeutic capacity by protecting against UV-induced skin hyperplasia and inhibiting tumor cell growth by attenuating TOPK signaling, respectively.

Alternative regulation of HIF-1α stability through Phosphorylation on Ser451.

The hypoxia-inducible factor (HIF-1α) functions as a master regulator of oxygen homeostasis. Oxygen-dependent hydroxylation of HIF-1α is tightly regulated by prolyl hydroxylase domain containing proteins (PHD1, PHD2, and PHD3). The prolyl hydroxylation facilitates the recruitment of the von Hippel-Lindau (VHL) protein, leading to ubiquitination and degradation of HIF-1α by the proteasomes. Besides prolyl hydroxylation, phosphorylation of HIF-1α is another central post-translational modification, which regulates its stability under hypoxic conditions as well as normoxic conditions. By use of LC/MS/MS-based analysis, we were able to identify a specific serine residue (Ser451) of HIF-1α phosphorylated under hypoxic conditions. Using plasmids expressing wild type (WT), non-phosphorylatable mutant HIF-1α (S451A), and phosphomimetic mutant HIF-1α (S451E), we demonstrated that the phosphorylation at Ser451 is important in maintaining the HIF-1α protein stability. Notably, phosphorylation at S451 interrupts the interaction of HIF-1α with PHD and pVHL. A phosphomimetic construct of HIF-1α at Ser451 (S451E) is significantly more stable than WT HIF-1α under normoxic conditions. Cells transfected with unphosphorylatable HIF-1α exhibited significantly lower HIF-1 transcriptional activity than WT cells and markedly reduced tumor cell migration. Further, tumors derived from the phosphomimetic mutant cells grew faster, whereas the tumors derived from non-phosphorylatable mutant cells grew slower than the control tumors, suggesting that the phosphorylation of HIF-1α at the Ser451 site is critical to promote tumor growth in vivo. Taken together, our data suggest an alternative mechanism responsible for the regulation of HIF-1α stability.

15-Deoxy-Δ12,14 -prostaglandin J2 binds and inactivates STAT3 via covalent modification of cysteine 259 in H-Ras-transformed human breast epithelial cells.

Signal transducer and activator of transcription 3 (STAT3) has been considered as a potential target for development of anticancer therapeutics. Here, we report a novel mechanism by which the cyclopentenone prostaglandin, 15-deoxy-Δ12,14 -prostaglandin J2 (15d-PGJ2 ) functions as an allosteric inhibitor of STAT3. 15d-PGJ2 inhibits phosphorylation, dimerization, nuclear translocation, and transcriptional activity of STAT3 in H-Ras-transformed human mammary epithelial cells (MCF10A-Ras) through the Michael addition reaction at cysteine 259 of STAT3. Comparative studies with 15d-PGJ2 analogues reveal that both C12-C13 and C9-C10 double bonds conjugated to the carbonyl group in the cyclopentenone ring of 15d-PGJ2 are essential for STAT3 binding. Antiproliferative and pro-apoptotic activities of 15d-PGJ2 in MCF10A-Ras cells are attributable to covalent modification of STAT3 on Cys259, and mimic the effects induced by mutation of this amino acid.

The peptidyl prolyl isomerase, PIN1 induces angiogenesis through direct interaction with HIF-2α.

PIN1, the peptidyl-prolyl isomerase (PPIase), is an enzyme that changes the conformation of phosphoproteins. The conformational change induced by PIN1 alters the function and stability of the target proteins. PIN1 is overexpressed in many different types of malignancies, including breast, lung, cervical, brain and colorectal tumors. PIN1 overexpression has been associated with activation of multiple oncogenic signaling pathways during tumor development. Hypoxia-inducible factor 2α (HIF-2α), a transcription factor activated in hypoxia, plays a role in erythropoiesis, glycolysis, tissue invasion, metastasis and angiogenesis. In this study, we found the direct interaction between HIF-2α and PIN1 in colorectal cancer HCT116 cells. Notably, serine 16 and lysine 63 residues of PIN1 were critical for its interaction with HIF-2α. When PIN1 protein was silenced by transient transfection of PIN1 short interfering RNA, the expression of HIF-2α was attenuated under a hypoxic condition. Moreover, genetic and pharmacologic inhibition of PIN1 abrogated the expression of vascular endothelial growth factor and angiogenesis. The cycloheximide chase experiment revealed the stabilization of HIF-2α by PIN1. Both WW and PPIase domains of PIN1 appear to be critical for its interaction with HIF-2α.

Targeting Wnt/ß-Catenin Pathway for Developing Therapies for Hair Loss.

Persistent hair loss is a major cause of psychological distress and compromised quality of life in millions of people worldwide. Remarkable progress has been made in understanding the molecular basis of hair loss and identifying valid intracellular targets for designing effective therapies for hair loss treatment. Whereas a variety of growth factors and signaling pathways have been implicated in hair cycling process, the activation of Wnt/ß-catenin signaling plays a central role in hair follicle regeneration. Several plant-derived chemicals have been reported to promote hair growth by activating Wnt/ß-catenin signaling in various in vitro and in vivo studies. This mini-review sheds light on the role of Wnt/ß-catenin in promoting hair growth and the current progress in designing hair loss therapies by targeting this signaling pathway.

Resveratrol suppresses gastric cancer cell proliferation and survival through inhibition of PIM-1 kinase activity.

The proviral integration site for Moloney murine leukemia virus (PIM) family of serine/threonine-specific kinases consist of three isoforms, that regulate proliferation, apoptosis, metabolism, invasion, and metastasis of cancer cells. Among these, abnormally elevated kinase activity of PIM-1 contributes to the progression of gastric cancer and predicts poor prognosis and a low survival rate in gastric cancer patients. In the present study, we found that resveratrol, one of the representative chemopreventive and anticarcinogenic phytochemicals, directly binds to PIM-1 and thereby inhibits its catalytic activity in human gastric cancer SNU-601 cells. This resulted in suppression of phosphorylation of the proapoptotic Bad, a known substrate of PIM-1. Resveratrol, by inactivating PIM-1, also inhibited anchorage-independent growth and proliferation of SNU-601 cells. To understand the molecular interaction between resveratrol and PIM-1, we conducted docking simulation and found that resveratrol directly binds to the PIM-1 at the ATP-binding pocket. In conclusion, the proapototic and anti-proliferative effects of resveratrol in gastric cancer cells are likely to be mediated through suppression of PIM-1 kinase activity, which may represent a novel mechanism underlying its chemopreventive and anticarcinogenic actions.

Acetylshikonin suppressed growth of colorectal tumour tissue and cells by inhibiting the intracellular kinase, T-lymphokine-activated killer cell-originated protein kinase.

BACKGROUND AND PURPOSE: Overexpression or aberrant activation of the T-lymphokine-activated killer cell-originated protein kinase (TOPK) promotes gene expression and growth of solid tumours, implying that TOPK would be a rational target in developing novel anticancer drugs. Acetylshikonin, a diterpenoid compound isolated from Lithospermum erythrorhizon root, exerts a range of biological activities. Here we have investigated whether acetylshikonin, by acting as an inhibitor of TOPK, can attenuate the proliferation of colorectal cancer cells and the growth of patient-derived tumours, in vitro and in vivo. EXPERIMENTAL APPROACH: Targets of acetylshikonin, were identified using kinase profiling analysis, kinetic/binding assay, and computational docking analysis and knock-down techniques. Effects of acetylshikonin on colorectal cancer growth and the underlying mechanisms were evaluated in cell proliferation assays, propidium iodide and annexin-V staining analyses and western blots. Patient-derived tumour xenografts in mice (PDX) and immunohistochemistry were used to assess anti-tumour effects of acetylshikonin. KEY RESULTS: Acetylshikonin directly inhibited TOPK activity, interacting with the ATP-binding pocket of TOPK. Acetylshikonin suppressed cell proliferation by inducing cell cycle arrest at the G1 phase, stimulated apoptosis, and increased the expression of apoptotic biomarkers in colorectal cancer cell lines. Mechanistically, acetylshikonin diminished the phosphorylation and activation of TOPK signalling. Furthermore, acetylshikonin decreased the volume of PDX tumours and reduced the expression of TOPK signalling pathway in xenograft tumours. CONCLUSION AND IMPLICATIONS: Acetylshikonin suppressed growth of colorectal cancer cells by attenuating TOPK signalling. Targeted inhibition of TOPK by acetylshikonin might be a promising new approach to the treatment of colorectal cancer.

Costunolide-A Bioactive Sesquiterpene Lactone with Diverse Therapeutic Potential.

Sesquiterpene lactones constitute a major class of bioactive natural products. One of the naturally occurring sesquiterpene lactones is costunolide, which has been extensively investigated for a wide range of biological activities. Multiple lines of preclinical studies have reported that the compound possesses antioxidative, anti-inflammatory, antiallergic, bone remodeling, neuroprotective, hair growth promoting, anticancer, and antidiabetic properties. Many of these bioactivities are supported by mechanistic details, such as the modulation of various intracellular signaling pathways involved in precipitating tissue inflammation, tumor growth and progression, bone loss, and neurodegeneration. The key molecular targets of costunolide include, but are not limited to, intracellular kinases, such as mitogen-activated protein kinases, Akt kinase, telomerase, cyclins and cyclin-dependent kinases, and redox-regulated transcription factors, such as nuclear factor-kappaB, signal transducer and activator of transcription, activator protein-1. The compound also diminished the production and/expression of proinflammatory mediators, such as cyclooxygenase-2, inducible nitric oxide synthase, nitric oxide, prostaglandins, and cytokines. This review provides an overview of the therapeutic potential of costunolide in the management of various diseases and their underlying mechanisms.

Cell growth inhibition by 3-deoxysappanchalcone is mediated by directly targeting the TOPK signaling pathway in colon cancer.

BACKGROUND: Colorectal cancer is one of the most common causes of cancer death worldwide. Unfortunately, chemotherapies are limited due to many complications and development of resistance and recurrence. The T-lymphokine-activated killer cell-originated protein kinase (TOPK) is highly expressed and activated in colon cancer, and plays an important role in inflammation, proliferation, and survival of cancer cells. Therefore, suppressing TOPK activity and its downstream signaling cascades is considered to be a rational therapeutic/preventive strategy against colon cancers. PURPOSE: 3-Deoxysappanchalcone (3-DSC), a component of Caesalpinia sappan L., is a natural oriental medicine. In this study, we investigated the effects of 3-DSC on colon cancer cell growth and elucidated its underlying molecular mechanism of targeting TOPK. STUDY DESIGN AND METHODS: To evaluate the effects of 3-DSC against colon cancer, we performed cell proliferation assays, propidium iodide- and annexin V-staining analyses and Western blotting. Targeting TOPK by 3-DSC was identified by a kinase-binding assay and computational docking models. RESULTS: 3-DSC inhibited the kinase activity of TOPK, but not mitogen-activated protein kinase (MEK). The direct binding of 3-DSC with TOPK was explored using a computational docking model and binding assay in vitro and ex vivo. 3-DSC inhibited colon cancer cell proliferation and anchorage-independent cell growth, and induced G2/M cell cycle arrest and apoptosis. Treatment of colon cancer cells with 3-DSC induced expression of protein that are involved in cell cycle (cyclin B1) and apoptosis (cleaved-PARP, cleaved-caspase-3, and cleaved-caspase-7), and suppressed protein expressions of extracellular signal-regulated kinase (ERK)-1/2, ribosomal S6 kinase (RSK), and c-Jun, which are regulated by the upstream kinase, TOPK. CONCLUSION: 3-DSC suppresses colon cancer cell growth by directly targeting the TOPK- mediated signaling pathway.

p21WAF1/Cip1 Regulation by hYSK1 Activates SP-1 Transcription Factor and Increases MMP-2 Expression under Hypoxic Conditions.

The hYSK1, a serine/threonine kinase (STK)-25, has been implicated in a variety of cellular functions including cell migration and polarity. We have recently reported that hYSK1 down-regulated the expression and functions of p16INK4a, a cell cycle regulatory protein, thereby enhancing migration and growth of cancer cells under hypoxic conditions. In this study, we further investigated the mechanisms underlying downregulation of p16INK4a and anti-migratory function of hYSK1. Our study revealed that p21WAF1/Cip1 is a novel binding partner of hYSK1. Moreover, the interaction between hYSK1 and p21WAF1/Cip1 led to the inhibition of SP-1 transcriptional activity, as revealed by a significant down-regulation of SP-1-mediated transactivation of p16INK4a promoter, and accelerated MMP-2 expression. Conversely, the knock-down of hYSK1 enhanced the p16INK4a promoter activity and protein expression, and diminished MMP-2 transcription and protein levels in hypoxic conditions as compared to control. Taken together, hYSK1 blocks the p21WAF1/Cip1 functions by direct interaction and inhibits the p16INK4a expression and induces MMP-2 expression by its regulations of SP-1 transcriptional activity under the hypoxia conditions.

Biochemical Basis of Anti-Cancer-Effects of Phloretin-A Natural Dihydrochalcone.

Apple is a rich source of bioactive phytochemicals that help improve health by preventing and/or curing many disease processes, including cancer. One of the apple polyphenols is phloretin [2',4',6'-Trihydroxy-3-(4-hydroxyphenyl)-propiophenone], which has been widely investigated for its antioxidant, anti-inflammatory and anti-cancer activities in a wide array of preclinical studies. The efficacy of phloretin in suppressing xenograft tumor growth in athymic nude mice implanted with a variety of human cancer cells, and the ability of the compound to interfere with cancer cells signaling, have made it a promising candidate for anti-cancer drug development. Mechanistically, phloretin has been reported to arrest the growth of tumor cells by blocking cyclins and cyclin-dependent kinases and induce apoptosis by activating mitochondria-mediated cell death. The blockade of the glycolytic pathway via downregulation of GLUT2 mRNA and proteins, and the inhibition of tumor cells migration, also corroborates the anti-cancer effects of phloretin. This review sheds light on the molecular targets of phloretin as a potential anti-cancer and anti-inflammatory natural agent.

Costunolide promotes the proliferation of human hair follicle dermal papilla cells and induces hair growth in C57BL/6 mice.

BACKGROUND: Costunolide (COS), a naturally occurring sesquiterpene lactone, is known to exert anti-inflammatory, antioxidant, and anticancer effects. This study was undertaken to investigate the effects of costunolide on the promotion of hair growth. METHODS: Real-time cell analyzer (RTCA), measurement of 5α-reductase activity, mRNA expression, and Western blotting were adopted to address whether COS can stimulate the proliferation of human hair follicle dermal papilla cells (hHFDPCs). The effect of COS on in vivo hair growth was examined by reconstitution assay and shaven dorsal skin in C57BL/6 mice. RESULTS: Costunolide significantly promoted the proliferation of hHFDPCs, which is comparable to that of tofacitinib. COS also inhibited the 5α-reductase activity in hHFDPCs. While COS increased the level of ß-catenin and Gli1 mRNA and proteins, it suppressed transforming growth factor (TGF)-ß1-induced phosphorylation of Smad-1/5 in hHFDPCs. COS increased the number of cultured hHFDPCs to induce hair follicles from mouse epidermal cells in Spheres formation of reconstitution assay. Topical application of COS on the shaven back of C57BL/6 mice significantly improved the hair growth. CONCLUSIONS: Our results illustrate that COS promotes hair growth in vitro and in vivo by regulating the amount of growth factors and/or the activity of cellular responses through coordination of the WNT-ß-catenin, hedgehog-Gli, and TGF-ß1-Smad pathways.

Hair-Growth Potential of Ginseng and Its Major Metabolites: A Review on Its Molecular Mechanisms.

The functional aspect of scalp hair is not only to protect from solar radiation and heat/cold exposure but also to contribute to one's appearance and personality. Progressive hair loss has a cosmetic and social impact. Hair undergoes three stages of hair cycle: the anagen, catagen, and telogen phases. Through cyclical loss and new-hair growth, the number of hairs remains relatively constant. A variety of factors, such as hormones, nutritional status, and exposure to radiations, environmental toxicants, and medications, may affect hair growth. Androgens are the most important of these factors that cause androgenic alopecia. Other forms of hair loss include immunogenic hair loss, that is, alopecia areata. Although a number of therapies, such as finasteride and minoxidil, are approved medications, and a few others (e.g., tofacitinib) are in progress, a wide variety of structurally diverse classes of phytochemicals, including those present in ginseng, have demonstrated hair growth-promoting effects in a large number of preclinical studies. The purpose of this review is to focus on the potential of ginseng and its metabolites on the prevention of hair loss and its underlying mechanisms.

Curcumin interacts directly with the Cysteine 259 residue of STAT3 and induces apoptosis in H-Ras transformed human mammary epithelial cells.

Signal transducer and activator of transcription 3 (STAT3) is a transcription factor that is latent but constitutively activated in many types of cancers. It is well known that STAT3 plays a key role in inflammation-associated tumorigenesis. Curcumin is an anti-inflammatory natural compound isolated from the turmeric (Curcuma longa L., Zingiberaceae) that has been extensively used in a traditional medicine over the centuries. In the present study, we have found that curcumin inhibits STAT3 signaling that is persistently overactivated in H-Ras transformed breast epithelial cells (H-Ras MCF10A). Specific cysteine residues present in STAT3 appear to be critical for the activity as well as conformation of this transcription factor. We identified the cysteine residue 259 of STAT3 as a putative site for curcumin binding. Site-directed mutation of this cysteine residue abolished curcumin-induced inactivation of STAT3 and apoptosis in H-Ras MCF10A cells. The α,ß-unsaturated carbonyl moiety of curcumin appears to be essential in its binding to STAT3 in H-Ras MCF10A cells. Tetrahydrocurcumin that lacks such electrophilic moiety failed to interact with STAT3 and to induce apoptosis in the same cell line. Taken together, our findings suggest that curcumin can abrogate aberrant activation of STAT3 through direct interaction, thereby inhibiting STAT3-mediated mammary carcinogenesis.

MMPP Attenuates Non-Small Cell Lung Cancer Growth by Inhibiting the STAT3 DNA-Binding Activity via Direct Binding to the STAT3 DNA-Binding Domain.

Rationale: Signal transducer and activator of transcription-3 (STAT3) plays a pivotal role in cancer biology. Many small-molecule inhibitors that target STAT3 have been developed as potential anticancer drugs. While designing small-molecule inhibitors that target the SH2 domain of STAT3 remains the leading focus for drug discovery, there has been a growing interest in targeting the DNA-binding domain (DBD) of the protein. Methods: We demonstrated the potential antitumor activity of a novel, small-molecule (E)-2-methoxy-4-(3-(4-methoxyphenyl)prop-1-en-1-yl)phenol (MMPP) that directly binds to the DBD of STAT3, in patient-derived non-small cell lung cancer (NSCLC) xenograft model as well as in NCI-H460 cell xenograft model in nude mice. Results: MMPP effectively inhibited the phosphorylation of STAT3 and its DNA binding activity in vitro and in vivo. It induced G1-phase cell cycle arrest and apoptosis through the regulation of cell cycle- and apoptosis-regulating genes by directly binding to the hydroxyl residue of threonine 456 in the DBD of STAT3. Furthermore, MMPP showed a similar or better antitumor activity than that of docetaxel or cisplatin. Conclusion: MMPP is suggested to be a potential candidate for further development as an anticancer drug that targets the DBD of STAT3.

hYSK1 promotes cancer cell proliferation and migration through negative regulation of p16INK4a under hypoxic conditions.

The alteration of expression of p16INK4a, a well-known cyclin-dependent kinase inhibitor involved in cell cycle control, in tumors is unclear, especially under hypoxic conditions. To evaluate p16INK4a regulation, we performed a protein microarray analysis. Among 1,800 proteins in the array, we identified hYSK1 as a novel protein that interacts with the tumor suppressor p16INK4a. hYSK1, a member of the Ste20 family of serine/threonine protein kinases, promotes cell migration and tumorigenesis and is activated by oxidative stress. However, the molecular mechanisms underlying the oncogenic potential of hYSK1 remain elusive. Here, we report that hYSK1 interacts with p16INK4a under hypoxic conditions in tumors, where it negatively regulates p16INK4a, enhancing cancer cell migration. Hypoxic stimulation of hYSK1 reduces p16INK4a accumulation through p16 promoter regulation to interact with unphosporylated SP-1 and increases matrix metalloproteinase-2 (MMP-2) expression by activating the MMP-2 promoter associated with cell migration and proliferation.Conversely, knocking down hYSK1 expression activated p16INK4a expression and suppressed MMP-2 expression. Thus, hYSK1 is necessary as a trigger for inactivating p16INK4a and activating MMP-2 during tumor migration, suggesting that hYSK1 is a specific negative regulator of the tumor suppressor p16INK4a and may represent a novel molecular target for reactivation of tumor suppressor genes in humans.

Dual Roles of Pin1 in Cancer Development and Progression.

Pin1 is a unique peptidyl-prolyl cis/trans isomerase (PPIase) that catalyzes the cis/trans isomerization of peptidyl-prolyl peptide bonds of its substrate proteins by binding to their specific phosphorylated Ser/Thr-Pro (pSer/Thr-Pro) motifs. This alters the conformation of target proteins and consequently affects their stability, intracellular localization, and/or biological functions. The abnormal overexpression of Pin1 is observed in some malignancies, which is associated with cancer cell proliferation, migration and invasion. However, a role for Pin1 as a putative tumor suppressor has recently been suggested. Systematic dissection of pro-oncogenic vs. tumor suppressive functions of Pin1 will be necessary.

Acetonitrile extract of Salvia miltiorrhiza Radix exhibits growth-inhibitory effects on prostate cancer cells through the induction of cell cycle arrest and apoptosis.

In the present study, the effects of the acetonitrile or water extracts from 400 selected traditional medicinal plants on the growth of PC-3 cells were investigated, and it was demonstrated that an acetonitrile extract of Salvia miltiorrhiza Radix exhibited the most marked cytotoxic effects on PC-3 cells. It was observed that the acetonitrile extract of S. miltiorrhiza Radix induced marked cell cycle arrest and apoptosis in PC-3 cells through the generation of intracellular reactive oxygen species. It was also demonstrated that oral administration of the acetonitrile extract of S. miltiorrhiza Radix decreased the incidence and growth of PC-3 tumor xenografts in nude mice. The results of the present study suggest that the acetonitrile extract of S. miltiorrhiza Radix exhibits marked inhibitory effects on the growth of prostate cancer cells in vitro and in vivo.