Targeting glutamine dependence with DRP-104 inhibits proliferation and tumor growth of castration-resistant prostate cancer.

BACKGROUND: Prostate cancer (PCa) continues to be one of the leading causes of cancer deaths in men. While androgen deprivation therapy is initially effective, castration-resistant PCa (CRPC) often recurs and has limited treatment options. Our previous study identified glutamine metabolism to be critical for CRPC growth. The glutamine antagonist 6-diazo-5-oxo-l-norleucine (DON) blocks both carbon and nitrogen pathways but has dose-limiting toxicity. The prodrug DRP-104 is expected to be preferentially converted to DON in tumor cells to inhibit glutamine utilization with minimal toxicity. However, CRPC cells' susceptibility to DRP-104 remains unclear. METHODS: Human PCa cell lines (LNCaP, LAPC4, C4-2/MDVR, PC-3, 22RV1, NCI-H660) were treated with DRP-104, and effects on proliferation and cell death were assessed. Unbiased metabolic profiling and isotope tracing evaluated the effects of DRP-104 on glutamine pathways. Efficacy of DRP-104 in vivo was evaluated in a mouse xenograft model of neuroendocrine PCa, NCI-H660. RESULTS: DRP-104 inhibited proliferation and induced apoptosis in CRPC cell lines. Metabolite profiling showed decreases in the tricarboxylic acid cycle and nucleotide synthesis metabolites. Glutamine isotope tracing confirmed the blockade of both carbon pathway and nitrogen pathways. DRP-104 treated CRPC cells were rescued by the addition of nucleosides. DRP-104 inhibited neuroendocrine PCa xenograft growth without detectable toxicity. CONCLUSIONS: The prodrug DRP-104 blocks glutamine carbon and nitrogen utilization, thereby inhibiting CRPC growth and inducing apoptosis. Targeting glutamine metabolism pathways with DRP-104 represents a promising therapeutic strategy for CRPC.

Non-canonical role of Hippo tumor suppressor serine/threonine kinase 3 STK3 in prostate cancer.

Serine/threonine kinase 3 (STK3) is an essential member of the highly conserved Hippo tumor suppressor pathway that regulates Yes-associated protein 1 (YAP1) and TAZ. STK3 and its paralog STK4 initiate a phosphorylation cascade that regulates YAP1/TAZ inhibition and degradation, which is important for regulated cell growth and organ size. Deregulation of this pathway leads to hyperactivation of YAP1 in various cancers. Counter to the canonical tumor suppression role of STK3, we report that in the context of prostate cancer (PC), STK3 has a pro-tumorigenic role. Our investigation started with the observation that STK3, but not STK4, is frequently amplified in PC. Additionally, high STK3 expression is associated with decreased overall survival and positively correlates with androgen receptor (AR) activity in metastatic castrate-resistant PC. XMU-MP-1, an STK3/4 inhibitor, slowed cell proliferation, spheroid growth, and Matrigel invasion in multiple models. Genetic depletion of STK3 decreased proliferation in several PC cell lines. In a syngeneic allograft model, STK3 loss slowed tumor growth kinetics in vivo, and biochemical analysis suggests a mitotic growth arrest phenotype. To further probe the role of STK3 in PC, we identified and validated a new set of selective STK3 inhibitors, with enhanced kinase selectivity relative to XMU-MP-1, that inhibited tumor spheroid growth and invasion. Consistent with the canonical role, inhibition of STK3 induced cardiomyocyte growth and had chemoprotective effects. Our results indicate that STK3 has a non-canonical role in PC progression and that inhibition of STK3 may have a therapeutic potential for PC that merits further investigation.

NUAK family kinase 2 is a novel therapeutic target for prostate cancer.

Current advancements in prostate cancer (PC) therapies have been successful in slowing PC progression and increasing life expectancy; however, there is still no curative treatment for advanced metastatic castration resistant PC (mCRPC). Most treatment options target the androgen receptor, to which many PCs eventually develop resistance. Thus, there is a dire need to identify and validate new molecular targets for treating PC. We found NUAK family kinase 2 (NUAK2) expression is elevated in PC and mCRPC versus normal tissue, and expression correlates with an increased risk of metastasis. Given this observation and because NUAK2, as a kinase, is actionable, we evaluated the potential of NUAK2 as a molecular target for PC. NUAK2 is a stress response kinase that also plays a role in activation of the YAP cotranscriptional oncogene. Combining pharmacological and genetic methods for modulating NUAK2, we found that targeting NUAK2 in vitro leads to reduction in proliferation, three-dimensional tumor spheroid growth, and matrigel invasion of PC cells. Differential gene expression analysis of PC cells treated NUAK2 small molecule inhibitor HTH-02-006 demonstrated that NUAK2 inhibition results in downregulation of E2F, EMT, and MYC hallmark gene sets after NUAK2 inhibition. In a syngeneic allograft model and in radical prostatectomy patient derived explants, NUAK2 inhibition slowed tumor growth and proliferation rates. Mechanistically, HTH-02-006 treatment led to inactivation of YAP and the downregulation of NUAK2 and MYC protein levels. Our results suggest that NUAK2 represents a novel actionable molecular target for PC that warrants further exploration.

Cyclin-dependent kinase 4 expression alters the number of keratinocyte stem cells in the mouse hair follicle.

Hair follicles regenerate periodically by spontaneously undergoing cycles of growth, regression, and relative quiescence. During the hair cycle, follicle stem cells residing in a specialized niche remain quiescent, and they are stimulated to proliferate throughout the growth phase of the hair follicle. Although cell cycle regulators play a prominent role during the activation of hair follicle stem cells, the identity and the role of these regulators have not been confirmed. Herein, we reported that stem cells located in the bulge region of the HF (BuSCs) express high levels of cyclin-dependent kinase 4 (CDK4) through the quiescent phase of the hair cycle. Using gain- and loss-of-function studies, we have determined that the CDK4 protein level affects the number of BuSCs. Transgenic expression of CDK4 in the bulge region of the hair follicles reduces the number of BuSCs, whereas CDK4 ablation resulted in an increasing number of BuSCs. These results suggest that deregulation of CDK4 protein levels contributes to distorting the self-renewal/proliferation balance and, in turn, altering the number of BuSCs.

Evidence for Feedback Regulation Following Cholesterol Lowering Therapy in a Prostate Cancer Xenograft Model.

BACKGROUND: Epidemiologic data suggest cholesterol-lowering drugs may prevent the progression of prostate cancer, but not the incidence of the disease. However, the association of combination therapy in cholesterol reduction on prostate or any cancer is unclear. In this study, we compared the effects of the cholesterol lowering drugs simvastatin and ezetimibe alone or in combination on the growth of LAPC-4 prostate cancer in vivo xenografts. METHODS: Proliferation assays were conducted by MTS solution and assessed by Student's t-test. 90 male nude mice were placed on a high-cholesterol Western-diet for 7 days then injected subcutaneously with 1 × 105 LAPC-4 cells. Two weeks post-injection, mice were randomized to control, 11 mg/kg/day simvastatin, 30 mg/kg ezetimibe, or the combination and sacrificed 42 days post-randomization. We used a generalized linear model with the predictor variables of treatment, time, and treatment by time (i.e., interaction term) with tumor volume as the outcome variable. Total serum and tumor cholesterol were measured. Tumoral RNA was extracted and cDNA synthesized from 1 ug of total RNA for quantitative real-time PCR. RESULTS: Simvastatin directly reduced in vitro prostate cell proliferation in a dose-dependent, cell line-specific manner, but ezetimibe had no effect. In vivo, low continuous dosing of ezetimibe, delivered by food, or simvastatin, delivered via an osmotic pump had no effect on tumor growth compared to control mice. In contrast, dual treatment of simvastatin and ezetimibe accelerated tumor growth. Ezetimibe significantly lowered serum cholesterol by 15%, while simvastatin had no effect. Ezetimibe treatment resulted in higher tumor cholesterol. A sixfold induction of low density lipoprotein receptor mRNA was observed in ezetimibe and the combination with simvastatin versus control tumors. CONCLUSIONS: Systemic cholesterol lowering by ezetimibe did not slow tumor growth, nor did the cholesterol independent effects of simvastatin and the combined treatment increased tumor growth. Despite lower serum cholesterol, tumors from ezetimibe treated mice had higher levels of cholesterol. This study suggests that induction of low density lipoprotein receptor is a possible mechanism of resistance that prostate tumors use to counteract the therapeutic effects of lowering serum cholesterol. Prostate 77:446-457, 2017. © 2016 Wiley Periodicals, Inc.

Angiotensin receptor signaling and prostate tumor growth in mice.

OBJECTIVE: The renin-angiotensin system, through its type 1 and type 2 angiotensin receptors (AT1R and AT2R, respectively) may have a role in prostate cancer. The objective of this pilot study was to explore that potential role by determining whether the AT1R blocker, losartan, would reduce the growth of LAPC-4 prostate cancer xenografts in nude mice. We also evaluated the tumor growth effects of using angiotensin II to activate both AT1R and AT2R simultaneously. Our data showed that losartan decreased tumor volumes by 56% versus control. This decrease reached statistical significance at day 54 (p = 0.0014). By day 54, Ki67 was also reduced in the losartan group, though not significantly so (p = 0.077). Losartan had no significant effect on AT1R or AT2R expression. Despite significant increases in both AT1R and AT2R at day 29 (p = 0.043 and 0.038, respectively), the administration of angiotensin II did not result in any significant differences in tumor volumes or ki67 at any time point. These data suggest that selective activation and induction of AT2R coupled with blockade of AT1R may slow prostate cancer growth. Future larger studies are needed to confirm these results.

Constitutive Stat3 activation alters behavior of hair follicle stem and progenitor cell populations.

STATs play crucial roles in a wide variety of biological functions, including development, proliferation, differentiation and migration as well as in cancer development. In the present study, we examined the impact of constitutive activation of Stat3 on behavior of keratinocytes, including keratinocyte stem cells (KSC) in vivo. BK5.Stat3C transgenic (Tg) mice, which express a constitutively active form of Stat3 (Stat3C) in the basal layer of the epidermis and in the bulge region KSCs exhibited a significantly reduced number of CD34+/α6 integrin+ cells compared to non-transgenic (NTg) littermates. There was a concomitant increase in the Lgr-6, Lrig-1, and Sca-1 populations in the Tg mice in contrast to the CD34 and Keratin-15 positive population. In addition, increased expression of c-myc, ß-catenin, and epithelial-mesenchymal transition (EMT)-related genes as well as decreased expression of α6-integrin was observed in the hair follicles of Tg mice. Notably, Sca-1 was found to be a direct transcriptional target of Stat3 in keratinocytes. The current data suggest that elevated Stat3 activity leads to depletion of hair follicle KSCs along with a concomitant increase of stem/progenitor cells above the bulge region. Overall, the current data indicate that Stat3 plays an important role in keratinocyte stem/progenitor cell homeostasis.

A novel mechanism of skin tumor promotion involving interferon-gamma (IFNγ)/signal transducer and activator of transcription-1 (Stat1) signaling.

The current study was designed to explore the role of signal transducer and activator of transcription 1 (Stat1) during tumor promotion using the mouse skin multistage carcinogenesis model. Topical treatment with both 12-O-tetradecanoylphorbol-13-acetate (TPA) and 3-methyl-1,8-dihydroxy-9-anthrone (chrysarobin or CHRY) led to rapid phosphorylation of Stat1 on both tyrosine (Y701) and serine (S727) residues in epidermis. CHRY treatment also led to upregulation of unphosphorylated Stat1 (uStat1) at later time points. CHRY treatment also led to upregulation of interferon regulatory factor 1 (IRF-1) mRNA and protein, which was dependent on Stat1. Further analyses demonstrated that topical treatment with CHRY but not TPA upregulated interferon-gamma (IFNγ) mRNA in the epidermis and that the induction of both IRF-1 and uStat1 was dependent on IFNγ signaling. Stat1 deficient (Stat1(-/-) ) mice were highly resistant to skin tumor promotion by CHRY. In contrast, the tumor response (in terms of both papillomas and squamous cell carcinomas) was similar in Stat1(-/-) mice and wild-type littermates with TPA as the promoter. Maximal induction of both cyclooxygenase-2 and inducible nitric oxide synthase in epidermis following treatment with CHRY was also dependent on the presence of functional Stat1. These studies define a novel mechanism associated with skin tumor promotion by the anthrone class of tumor promoters involving upregulation of IFNγ signaling in the epidermis and downstream signaling through activated (phosphorylated) Stat1, IRF-1 and uStat1.

Skp2 deficiency inhibits chemical skin tumorigenesis independent of p27(Kip1) accumulation.

S-phase kinase-associated protein 2 (Skp2) functions as the receptor component of the Skp-Cullin-F-box complex and is implicated in the degradation of several cell cycle regulators, such as p21(Cip1), p27(Kip1), p57(Kip2), and cyclin E. Numerous studies in human and experimental tumors have demonstrated low p27(Kip1) levels and elevated Skp2 expression. However, a direct association between the inverse correlation of Skp2 and p27(Kip1) with tumorigenesis has not been demonstrated. Herein, we provide evidence that skin tumorigenesis is inhibited in Skp2(-/-) mice. An analysis of mouse keratinocytes indicates that increased p27(Kip1) levels in Skp2(-/-) epidermis cause reduced cell proliferation that is alleviated in the epidermis from Skp2(-/-)/p27(-/-) compound mice. In contrast, we establish that a p27(Kip1) deficiency does not overturn the reduced skin tumorigenesis experienced by Skp2(-/-) mice. In addition, Skp2(-/-) epidermis exhibits an accumulation of p53-cofactor CBP/p300 that is associated with elevated apoptosis in hair follicles and decreased skin tumorigenesis. We conclude that p27(Kip1) accumulation is responsible for the hypoplasia observed in normal tissues of Skp2(-/-) mice but does not have a preponderant function in reducing skin tumorigenesis.

[Avifauna in silvopastoral systems in the Mesoamerican Biological Corridor, Tabasco, México]. / Avifauna en sistemas silvopastoriles en el Corredor Biológico Mesoamericano, Tabasco, México.

Silvopastoral systems support local ecological and economical features as they enhance conservation of floral and faunal communities. As other animal communities, avifauna may be a good representative of habitat alterations, both as the species and functional levels. In order to attend the initiative of Mesoamerican Biological Corridor initiative (CBM) in the state of Tabasco, we studied the diversity of birds in two silvopastoral systems: scattered trees in pastures (ADP), and trees in boundary-hedgerows (AL). For this, we applied the fixed radius counting point method in three priority sites in Tabasco's CBM during the dry and wet season of 2011, and a total of 56, 60 and 62 points were evaluated in Huimanguillo, Tenosique and Tacotalpa, respectively. We observed 2 084 individuals of 154 species (79-89% of expected diversity) and 36 bird families. We detected 92, 87 and 85 species in Huimanguillo, Tenosique and Tacotalpa, respectively, including 35 protected species, of which 23, 19 and 16 in each locality, respectively. All sites showed high diversity (H' ≥ 3.20), low species dominance (D ≥ 0.08) and high equitability (J ≥ 0.77). Species composition showed differences between sites, being most similar Tacotalpa and Tenosique. Ten species were considered characteristic for sites. Although the silvopastoral system did contain protected species, the low diversity and the early successional character of the arboreal components were not attractive to frugivorous bird species. Diversification with native trees can improve the systems to create a complementary habitat and to increase landscape connectivity. The management of silvopastoral practices on cattle dominated landscapes in Tabasco could improve its ecological quality, and thus achieve the CBM's objectives ofbiodiversity conservation combined with human economic activities.

Genotoxic Effects on Gas Station Attendants in South-southeastern México due to Prolonged and Chronic Exposure to Gasoline.

Background: Gasoline, a complex mixture of volatile organic compounds is classified as possibly carcinogenic to humans. Gasoline station attendants, consistently exposed to its hazardous components, may face genotoxic effects. This study aimed to assess the influence of varying work shift durations on DNA damage in gasoline station attendants. Methods: Ninety individuals from three locations in southern México were studied. Peripheral blood mononuclear cells (PBMCs) were isolated, and DNA damage was assessed using the comet assay. Demographic, occupational, and lifestyle data were collected. Statistical analyses included t-tests, ANOVA, and Pearson correlation. Results: Significant differences in DNA damage parameters were observed between exposed and unexposed groups. The impact of tobacco, alcohol, and exercise on DNA damage was negligible. Extended work shifts (12 and 24 hours) showed heightened DNA damage compared to 8-hour shifts and the unexposed group. A novel finding revealed a modest but significant correlation between DNA damage and job seniority. Conclusion: The study highlights the intricate relationship between occupational exposure to gasoline components, DNA damage, and work shift lengths. Extended shifts correlate with heightened genotoxic effects, emphasizing the importance of personalized safety measures. The significant correlation between DNA damage and job seniority introduces occupational longevity as a determinant in the genetic health of gasoline station attendants. This discovery has implications for implementing targeted interventions and preventive strategies to safeguard workers' genetic integrity throughout their years of service. The study calls for further exploration of unconsidered factors in understanding the multifactorial nature of DNA damage in this occupational setting.

Heat shock factor 1 directly regulates transsulfuration pathway to promote prostate cancer proliferation and survival.

There are limited therapeutic options for patients with advanced prostate cancer (PCa). We previously found that heat shock factor 1 (HSF1) expression is increased in PCa and is an actionable target. In this manuscript, we identify that HSF1 regulates the conversion of homocysteine to cystathionine in the transsulfuration pathway by altering levels of cystathionine-ß-synthase (CBS). We find that HSF1 directly binds the CBS gene and upregulates CBS mRNA levels. Targeting CBS decreases PCa growth and induces tumor cell death while benign prostate cells are largely unaffected. Combined inhibition of HSF1 and CBS results in more pronounced inhibition of PCa cell proliferation and reduction of transsulfuration pathway metabolites. Combination of HSF1 and CBS knockout decreases tumor size for a small cell PCa xenograft mouse model. Our study thus provides new insights into the molecular mechanism of HSF1 function and an effective therapeutic strategy against advanced PCa.

[Microorganisms effect with probiotic potential in water quality and growth of the shrimp Litopenaeus vannamei (Decapoda: Penaeidae) in intensive culture]. / Efecto de microorganismos con potencial probiótico en la calidad del agua y el crecimiento de camarón Litopenaeus vannamei (Decapoda: Penaeidae) en cultivo intensivo.

The use of probiotics has gained acceptance in aquaculture, particularly in maintaining water quality and enhancing growth in organisms. This study analyzed the effect of the commercial (EM, Japan) natural product composed by (Rhodopseudomonas palustris, Lactobacillus plantarum, Lactobacillus casei and Saccharomyces cerevisiae) added to the water, in order to determine its effect in water quality, sediment and growth of L. vannamei under intensive culture. The evaluation included three treatments with a weekly addition of EM: i) tanks without probiotics (C), ii) tanks with a dose of 4 L/ha (EM1) and iii) tanks with a dose of 10 L/ha (EM2). The treatment C was carried out three times, while treatments EM1 and EM2 were carried out four times. A total of 4 350 shrimps were measured for total length and weight, to calculate total and porcentual weight gain, daily weight gain, specific growth rate (TCE), and food conversion factor (FCA); besides, the survival rate was estimated. The use of probiotics allowed a shorter harvest time in treatments EM1 (90 d) and EM2 (105 d) with relation to the treatment C (120d). Treatments EM1 and EM2 were within the recommended intervals for culture, with respect to treatment C. The use of probiotic bacteria significantly regulated pH (EM1, 8.03 +/- 0.33; EM2, 7.77 +/- 0.22; C, 9.08 +/- 0.35) and reduced nitrate concentration (EM1, 0.64 +/- 0.25 mg/L; EM2, 0.39 +/- 0.26 mg/L; C, 0.71 mg/L). Water pH mostly explained the variance with respect to the treatments. Treatment EM2 presented the greatest removal of organic matter (1.77 +/- 0.45%), whereas the contents of extractable phosphorus increased significantly in treatment EM1 with 21.6 +/- 7.99 mg/kg and in treatment EM2 with 21.6 +/- 8.45 mg/kg with control relation (14.3 +/- 5.47). The shrimp growth was influenced by dissolved oxygen, salinity and pH in the sediment, establishing that salinity was the most important variable in the weight with a negative association. Treatment EM1 recorded an improved TCE (2.69 +/- 0.35%/d) and FCA (1.46 +/- 0.20) with relation to the control treatment (TCE, 1.88 +/- 0.25%/d; FCA, 2.13 +/- 0.48). Survival was significantly greater in treatments containing probiotics with 61 +/- 8.76% and 60 +/- 10.5% for EM1 and EM2, respectively. This study indicated the positive effect obtained with the use of this commercial probiotic, to improve culture conditions and growth parameters in an intensive culture of L. vannamei.

Targeting the Divergent Roles of STK3 Inhibits Breast Cancer Cell Growth and Opposes Doxorubicin-Induced Cardiotoxicity In Vitro.

Breast cancer (BCa) is the most prevalent type of cancer in women. Several therapies used in the treatment of breast cancer are associated with clinically important rates of cardiovascular toxicity during or after treatment exposure, including anthracyclines. There is a need for new BCa therapeutics and treatments that mitigate chemotherapy-induced cardiotoxicity in BCa. In this study, we examine the effects of Serine/Threonine Kinase 3 (STK3) inhibition in the context of BCa therapy and cardioprotection from doxorubicin. STK3 (also known as MST2) is a key member of the Hippo Tumor-Suppressor Pathway, which regulates cell growth and proliferation by inhibiting YAP/TAZ co-transcription factors. Canonically, STK3 should restrict BCa growth; however, we observed that STK3 is amplified in BCa and associated with worse patient outcomes, suggesting a noncanonical pro-tumorigenic role. We found BCa cell lines have varying dependence on STK3. SUM52PE cells had the highest expression and dependence on STK3 in genetic and pharmacological assays. MCF-7 and MDA-MB-231 were less sensitive to STK3 targeting in standard proliferation assays, but were STK3 dependent in colony formation and matrigel invasion assays. In contrast, STK3 inhibition mitigated the toxic effects of doxorubicin in H9C2 rat cardiomyocytes by increasing YAP expression. Importantly, STK3 inhibition in BCa cells did not interfere with the therapeutic effects of doxorubicin. Our studies highlight STK3 is a potential molecular target for BCa with dual therapeutic effects: suppression of BCa growth and progression, and chemoprotection in cardiomyocytes.

The effects of glycemic index on prostate cancer progression in a xenograft mouse model.

BACKGROUND: Previously, we found low-carbohydrate diets slowed prostate cancer (PC) growth and increased survival vs. a Western diet in mice, by inhibiting the insulin/IGF-1 axis. Thus, we tested whether modifying carbohydrate quality to lower glycemic index (GI) without changing quantity results in similar benefits as with reduced quantity. METHODS: Male SCID mice injected with LAPC-4 cells were single-housed and randomized when their tumors reached 200 mm3 on average to a LoGI (48% carbohydrate kcal, from Hylon-VII) or HiGI Western diet (48% carbohydrate kcal, from sucrose). Body weight and tumor volume were measured weekly. Body composition was assessed 35 days after randomization. Blood glucose and serum insulin, IGF-1 and IGFBP3 were measured at study end when tumor volumes reached 800 mm3. We analyzed gene expression of mice tumors by RNA-sequencing and human tumors using the Prostate Cancer Transcriptome Atlas. RESULTS: There were no significant differences in tumor volume (P > 0.05), tumor proliferation (P = 0.29), and overall survival (P = 0.15) between groups. At 35 days after randomization, the LoGI group had 30% lower body fat (P = 0.007) despite similar body weight (P = 0.58). At sacrifice, LoGI mice had smaller livers (P < 0.001) and lower glucose (P = 0.15), insulin (P = 0.11), IGF-1 (P = 0.07) and IGF-1:IGFBP3 ratio (P = 0.05), and higher IGFBP3 (P = 0.09) vs. HiGI, although none of these metabolic differences reached statistical significance. We observed differential gene expression and pathway enrichment in mice tumors by diet. The most upregulated and downregulated gene in the LoGI group showed expression patterns more closely resembling expression in human benign prostate tissue vs. PC. CONCLUSIONS: In this single mouse xenograft model, consuming a low GI diet did not delay PC growth or survival vs. a high GI diet despite suggestions of decreased activation of the insulin/IGF-1 pathway. These data suggest that improving carbohydrate quality alone while consuming a high carbohydrate diet may not effectively slow PC growth.

Skp2 is necessary for Myc-induced keratinocyte proliferation but dispensable for Myc oncogenic activity in the oral epithelium.

The proto-oncogene c-Myc encodes a transcription factor that is implicated in the regulation of cellular proliferation, differentiation, and apoptosis. Myc accelerates the rate of cell proliferation, at least in part, through its ability to down-regulate the expression of the cell cycle inhibitor p27(Kip1). Moreover, p27(Kip1) protein levels are regulated by ubiquitin-mediated turnover, leading to destruction by the E3 ubiquitin ligase SCF(Skp2). Therefore, we hypothesize that a lack of Skp2 expression should lead to increased p27(Kip1) levels and further inhibition of Myc-mediated proliferation and tumorigenesis. Myc expression in epithelial tissues of transgenic mice (K5-Myc) led to increased keratinocyte proliferation and the development of spontaneous tumors within the oral cavity. We generated K5-Myc-transgenic mice in an Skp2-null background. Consistent with our hypothesis, we found that Myc-mediated keratinocyte hyperproliferation was abolished by the loss of Skp2. However, Skp2 ablation did not affect Myc-driven tumorigenesis because the incidence, latency, and degree of differentiation of oral tumors were identical between K5-Myc/Skp2(+/+) and K5-Myc/Skp2(-/-) mice. Altogether, these findings suggest that Skp2 and p27(Kip1) are critical for Myc-driven keratinocyte proliferation; however, Myc-mediated tumorigenesis in the oral epithelium is independent of the Skp2-p27(Kip1) axis.

Faunistic analysis of the caridean shrimps inhabiting seagrasses along the NW coast of the Gulf of Mexico and Caribbean Sea.

Seagrass meadows are highly productive and ecologically important habitats in estuaries and coastal lagoons, and contain a variety of faunal communities, from which the caridean shrimps are a dominant component. The purpose of this work was to analyze the environmental parameters of water and sediments, with the biological components in seagrass epifaunal communities, from the Western Gulf of Mexico and the Caribbean Sea. For this, density and diversity of caridean shrimps were analyzed and correlated with environmental parameters and seagrass biomass, and zoogeographic affinities were determined. The spatial distribution of caridean shrimps was recorded for 12 localities with Halodule wrightii and Thalassia testudinum monospecific seagrass meadows. A total of 72158 individuals of 16 taxa were collected. Among results, the Hippolytidae resulted the most abundant group (92.3%) with eight species, and was followed by Palaemonidae with 7.6% of the abundance and seven species, and the Alpheidae with only one genus. From the total of collected carideans, a 37.3% was found in H. wrightii and 62.7% in T. testudinum. The dominant species were Hippolyte zostericola (12.39ind./m2), Tozeuma carolinense (9.5ind./m2), Thor dobkini (4.84ind./m2) and Palaemonetes vulgaris (4.87ind./m2). The zoogeographic distribution of the carideans presented two groups: species of the Virginian-Carolinean province representing its Southern limit (43.75%) and species of the Brazilian-Caribbean province representing its Northern limit (56.25%). The species H. zostericola, T. carolinense, P. vulgaris, P. pugio and P. intermedius are widely distributed along the Western Atlantic coast. This study has base line information for seagrass habitats, the community of epifaunal carideans and their ecological affinities, previous to the oil spill in the Gulf of Mexico.

MESH1 knockdown triggers proliferation arrest through TAZ repression.

All organisms are constantly exposed to various stresses, necessitating adaptive strategies for survival. In bacteria, the main stress-coping mechanism is the stringent response triggered by the accumulation of "alarmone" (p)ppGpp to arrest proliferation and reprogram transcriptome. While mammalian genomes encode MESH1-the homolog of the (p)ppGpp hydrolase SpoT, current knowledge about its function remains limited. We found MESH1 expression tended to be higher in tumors and associated with poor patient outcomes. Consistently, MESH1 knockdown robustly inhibited proliferation, depleted dNTPs, reduced tumor sphere formation, and retarded xenograft growth. These antitumor phenotypes associated with MESH1 knockdown were accompanied by a significantly altered transcriptome, including the repressed expression of TAZ, a HIPPO coactivator, and proliferative gene. Importantly, TAZ restoration mitigated many anti-growth phenotypes of MESH1 knockdown, including proliferation arrest, reduced sphere formation, tumor growth inhibition, dNTP depletion, and transcriptional changes. Furthermore, TAZ repression was associated with the histone hypo-acetylation at TAZ regulatory loci due to the induction of epigenetic repressors HDAC5 and AHRR. Together, MESH1 knockdown in human cells altered the genome-wide transcriptional patterns and arrested proliferation that mimicked the bacterial stringent response through the epigenetic repression of TAZ expression.

[Ichthyofauna from wetlands of San Pedro, Balancán, Tabasco, México]. / Ictiofauna de los humedales del río San Pedro, Balancán, Tabasco, México.

San Pedro River's wetlands sustain trophic nets in the fluvial system, due to the high habitat availability, and space and temporal variations. In order to describe the relationship between environmental parameters and ichthyofauna, this study evaluated fish assemblages composition, distribution, abundance, density, biomass, richness species, diversity and equitability in the wetlands. Sampling considered three different sites and climatic seasons (dry, rainy and cold fronts). The physical and chemical parameters considered were dissolved oxygen, temperature, pH, water transparency and the depth. Fishes were caught with a shrimp net, after six minutes towings and were identified afterwards. A total of 1 049 organisms of 25 fish species were caught, two of which were exotic species: Oreochromis niloticus and Parachromis managuense. A total of 23 species were found at site I (with the highest density 0.23 ind./m2), 17 at site II (0.23 ind./m2) and 14 at site III (0.12 ind./m2). The dry season had the highest species number with 21 species, followed by the rainy season with 17 species, and the cold season with five species. Similarly, the highest biomass (8.30 g/m2) was found in dry season, followed by the rainy (2.16 g/m2) and the cold seasons (0.03 g/m2). Considering seasons, highest density was found during the dry (0.436 ind./m2), followed by the rainy (0.213 ind./m2) and the cold (0.023 ind./m2) seasons. The dominant density species during the study period, according to the quadrants graphic of Olmstead-Tukey were: Petenia splendida, Vieja heterospila, Vieja synspila, Dorosoma petenense and Astyanax aeneus. There were significant differences in the species richness among sites. Temperature, depth and transparency showed differences among the seasons. The canonical correspondence analysis indicated that fish distribution was governed by environmental parameters during all seasons. In terms of fish abundance and composition, environmental parameters play an important role showing spatial and temporal differences in the ecosystem, this could be explained with the fact that most of young fishes have a movement behavior to the wetlands, searching refuge and feed during the dry season. Considering the diversity indexes variation, it may be concluded that San Pedro River's wetlands correspond to a system where the ichthyofauna composition fluctuates spatial and seasonally.

Taxonomic and functional responses of macroinvertebrates to riparian forest conversion in tropical streams.

Land use change threatens the ecological integrity of tropical rivers and streams; however, few studies have simultaneously analyzed the taxonomic and functional responses of tropical macroinvertebrates to riparian forest conversion. Here, we used community structure, functional diversity, and stable isotope analyses to assess the impacts of riparian deforestation on macroinvertebrate communities of streams in southern Mexico. Monthly sampling during the dry season was conducted in streams with riparian forest (forest streams), and in streams with pasture dominating the riparian vegetation (pasture streams). Samples were collected for water quality (physical-chemical variables, nutrient concentrations, and total suspended solids), organic matter (leaf litter abundance and algal biomass), and macroinvertebrate abundance and diversity. Higher temperature, conductivity, suspended solids, and chlorophyll a were detected in pasture streams, while nitrate concentrations and leaf litter biomass were greater in forest streams. Macroinvertebrate density was higher in pasture sites, while no differences in taxonomic diversity and richness were found between land uses. Functional evenness was greater in forest streams, while richness and divergence were similar between land uses, despite differences in taxonomic composition. Environmental variables were associated with taxa distribution but not with functional traits, suggesting current conditions still promote redundancy in ecological function. Isotopic analyses indicated consumers in pasture streams were enriched in 13C and 15N relative to forest streams, potentially reflecting the higher algal biomass documented in pasture systems. Isotopic niches were broader and more overlapped in pasture streams, indicating more generalist feeding habits. No significant losses of taxonomic or functional diversity were detected in pasture streams. However, changes in trophic ecology suggest landscape-level processes are altering macroinvertebrate feeding habits in streams. The changes we observed in habitat, water quality, and macroinvertebrate community were related to the removal of the riparian vegetation, suggesting the structure and function of the focal systems would benefit from riparian restoration.