Stability of Human Telomeric G-Quadruplexes Complexed with Photosensitive Ligands and Irradiated with Visible Light.

Guanine-rich DNA sequences can fold into non-canonical nucleic acid structures called G-quadruplexes (G4s). These nanostructures have strong implications in many fields, from medical science to bottom-up nanotechnologies. As a result, ligands interacting with G4s have attracted great attention as candidates in medical therapies, molecular probe applications, and biosensing. In recent years, the use of G4-ligand complexes as photopharmacological targets has shown significant promise for developing novel therapeutic strategies and nanodevices. Here, we studied the possibility of manipulating the secondary structure of a human telomeric G4 sequence through the interaction with two photosensitive ligands, DTE and TMPyP4, whose response to visible light is different. The effect of these two ligands on G4 thermal unfolding was also considered, revealing the occurrence of peculiar multi-step melting pathways and the different attitudes of the two molecules on the quadruplex stabilization.

Genomic Profiling of HER2-Positive Gastric Cancer: PI3K/Akt/mTOR Pathway as Predictor of Outcomes in HER2-Positive Advanced Gastric Cancer Treated with Trastuzumab.

BACKGROUND: HER2-positive gastric cancer (GC) affects 7%-34% of patients with GC. Trastuzumab-based first-line treatment has become the standard of care for HER2-positive advanced gastric cancer (AGC). However, there are no clinically validated biomarkers for resistance to HER2-targeted therapies. Upregulation of PI3K pathway and tyrosine kinase receptor (TKR) alterations have been noted as molecular mechanisms of resistance in breast cancer. Our study aimed to perform a molecular characterization of HER2-positive AGC and investigate the role of PI3K/Akt/mTOR signaling pathway activation and TKR gene copy number (GCN) gains as predictive biomarkers in HER2-positive AGC treated with trastuzumab. PATIENTS AND METHODS: Forty-two HER2-positive GC samples from patients treated with trastuzumab-based first-line chemotherapy were selected. DNA samples were sequenced. PTEN and MET immunohistochemistry were also performed. RESULTS: Concurrent genetic alterations were detected in 97.1% of HER2-positive AGC. We found activation of PI3K/Akt/mTOR pathway in 52.4% of patients and TKR GCN gains in 38.1%. TKR GCN gains did not correlate with overall survival (OS) or progression-free survival (PFS). Multivariate Cox models showed that PI3K/Akt/mTOR activation negatively affects the effectiveness of trastuzumab-based chemotherapy in terms of OS and PFS. CONCLUSION: Our results provide for the first time a detailed molecular profile of concurrent genetic alterations in HER2-positive AGC. PI3K pathway activation could be used as a predictive marker of worse outcome in this patient population. In addition, gains in copy number of other TKR genes in this subgroup may also influence the survival benefit obtained with trastuzumab. IMPLICATIONS FOR PRACTICE: This article reports, for the first time, a detailed molecular profile of genomic alterations in patients with HER2-positive advanced gastric cancer (AGC). PI3K/Akt/mTOR signaling pathway activation seems to have a differentially negative effect on overall survival and progression-free survival in AGC treated with trastuzumab-based chemotherapy. Combining different targeted agents could be a successful therapeutic strategy to improve the prognosis of HER2-positive AGC.

[Systemic lupus erythematous and CD24v]. / Lupus eritematoso sistémico y CD24v.

BACKGROUND: Systemic lupus erythematous is an autoimmune disease of multifactorial etiology with genetic predisposition. Its pathogenesis involved more than 100 genes. CD24 gene can mediate various functions such as their costimulatory activity in the clonal expansion of T cells. The single nucleotide polymorphism, resulting in a non-conservative replacement of alanine to valine (CD24v) precedes immediately GPI anchorage site (position ω-1), determines CD24 loss activity. CD24v has been associated with multiple sclerosis and systemic lupus erythematous in other populations. OBJECTIVE: To find the presence of CD24v in Mexican patients with systemic lupus erythematous. MATERIAL AND METHOD: A study of fenotyping of CD24v included 65 subjects, 32 cases (systemic lupus erythematous): 28 women and 4 men; and 32 controls: 9 women and 23 men; cases and controls from patients with systemic lupus erythematous in National Medical Center 20 de Noviembre ISSSTE, Mexico City, services of Clinical Immunology and Rheumatology. RESULTS: In cases, 19 patients had a wild homozygous genotype, 12 were heterozygous and only one patient showed homozygous polymorphism. In controls, 17 showed wild heterozygous genotypes; 14 were heterozygous and 1 was found to be polymorphic homozygote. With odds ratio: 0.84 and chi-squared of 0.17; therefore there was no statistically significant difference. CONCLUSIONS: Study population showed that there is no statistically significant difference between systemic lupus erythematous cases and controls with respect to the presence of CD24v.

Antecedentes: el lupus eritematoso sistémico es un padecimiento autoinmunitario, de origen multifactorial, con predisposición genética; más de 100 genes participan en su etiopatogenia. El gen de CD24 puede mediar varias funciones, como su actividad coestimuladora en la expansión clonal de las células T. El polimorfismo de un simple nucleótido de CD24, que resulta en un reemplazo no conservador de alanina a valina (CD24v), que precede inmediatamente al sitio de anclaje GPI (posición ω-1), condiciona la pérdida de actividad de CD24. Se ha descrito que CD24v está asociado con esclerosis múltiple y lupus eritematoso sistémico en otras poblaciones. Objetivo: encontrar la existencia de CD24v en pacientes mexicanos con lupus eritematoso sistémico. Material y método: estudio de genotipificación de CD24v en el que se incluyeron 64 sujetos, 32 casos con lupus eritematoso sistémico: 28 mujeres y 4 hombres; y 32 controles: 9 mujeres y 23 hombres; todos eran pacientes con lupus eritematoso sistémico del Centro Médico Nacional 20 de Noviembre, del ISSSTE, atendidos en los servicios de Inmunología Clínica y Reumatología. Resultados: de los casos, 19 pacientes tenían genotipo homocigoto silvestre, 12 con genotipo heterocigotos y sólo un paciente mostró el polimorfismo en estado homocigoto. De los controles, 17 sujetos mostraron genotipos heterocigotos silvestres, 14 eran heterocigotos y sólo en uno se encontró que era homocigoto polimórfico. Se obtuvo una razón de momios de 0.84 y chi cuadrada de 0.17, por lo que no hubo diferencia estadísticamente significativa. Conclusiones: se demostró que no hay diferencia estadísticamente significativa entre pacientes con lupus eritematoso sistémico y controles respecto a la existencia de CD24v.

Utilidad de los marcadores tumorales en el tratamiento de los tumores germinales / Utility of tumor markers in the treatment of germ cell tumors

OBJETIVO: Revisar el estado actual de la utilidad de los marcadores tumorales en el tratamiento de los tumores seminales. MÉTODO: Se han revisado los artículos publicados hasta la actualidad referentes al tema. RESULTADOS/CONCLUSIONES: Los marcadores tumorales (alfa-fetoproteína, Beta-HCG y LDH) constituyen un elemento esencial en el manejo de los tumores germinales. Son de gran utilidad en el diagnóstico inicial y el diagnóstico de extensión tras la cirugía, especialmente de la enfermedad residual postcirugía en el estadio I. Su papel como marcador pronóstico ha quedado claramente establecido en la clasificación IGCCCG. Por otro lado, una de sus utilidades más importantes se encuentra en el seguimiento y detección de recidivas, así como en la monitorización de la respuesta al tratamiento Es preciso conocer una serie de situaciones en las que pueden producirse elevaciones espúreas de marcador, no debidas a progresión tumoral. La elevación de Alfafetoproteína puede ser causada por daño hepático y lisis tumoral. La elevación de Beta-HCG puede deberse a hipogonadismo, lisis tumoral, elevación discordante, o efecto "hook" (AU)