Normal vision and development in mice with low functional expression of Kir7.1 in heterozygosis for a blindness-producing mutation inactivating the channel.

K+ channel Kir7.1 expressed at the apical membrane of the retinal pigment epithelium (RPE) plays an essential role in retinal function. An isoleucine-to-threonine mutation at position 120 of the protein is responsible for blindness-causing vitreo-retinal dystrophy. We have studied the molecular mechanism of action of Kir7.1-I120T in vitro by heterologous expression and in vivo in CRISPR-generated knockin mice. Full-size Kir7.1-I120T reaches the plasma membrane but lacks any activity. Analysis of Kir7.1 and the I120T mutant in mixed transfection experiments, and that of tandem tetrameric constructs made by combining wild type (WT) and mutant protomers, leads us to conclude that they do not form heterotetramers in vitro. Homozygous I120T/I120T mice show cleft palate and tracheomalacia and do not survive beyond P0, whereas heterozygous WT/I120T develop normally. Membrane conductance of RPE cells isolated from WT/WT and heterozygous WT/I120T mice is dominated by Kir7.1 current. Using Rb+ as a charge carrier, we demonstrate that the Kir7.1 current of WT/I120T RPE cells corresponds to approximately 50% of that in cells from WT/WT animals, in direct proportion to WT gene dosage. This suggests a lack of compensatory effects or interference from the mutated allele product, an interpretation consistent with results obtained using WT/- hemizygous mouse. Electroretinography and behavioral tests also show normal vision in WT/I120T animals. The hypomorphic ion channel phenotype of heterozygous Kir7.1-I120T mutants is therefore compatible with normal development and retinal function. The lack of detrimental effect of this degree of functional deficit might explain the recessive nature of Kir7.1 mutations causing human eye disease.NEW & NOTEWORTHY Human retinal pigment epithelium K+ channel Kir7.1 is affected by generally recessive mutations leading to blindness. We investigate one such mutation, isoleucine-to-threonine at position 120, both in vitro and in vivo in knockin mice. The mutated channel is inactive and in heterozygosis gives a hypomorphic phenotype with normal retinal function. Mutant channels do not interfere with wild-type Kir7.1 channels which are expressed concomitantly without hindrance, providing an explanation for the recessive nature of the disease.

Análisis de la coexpresión de HER2/GRB7 y su asociación con variables clinicopatológicas en un grupo de mujeres colombianas con diagnóstico de cáncer de mama invasivo / Analysis of HER2/GRB7 co-expression and its association with clinicopathological variables in a group of Colombian women diagnosed with invasive breast cancer

Objetivo. Analizar las diferencias en la presentación de variables clínico-patológicas, de acuerdo con la expresión proteica de GRB7, en tumores HER2 positivos en mujeres colombianas con cáncer de mama invasivo, diagnosticado entre los años 2013 y 2015 en el Instituto Nacional de Cancerología E.S.E (INC). Métodos. Se incluyeron 158 pacientes con diagnóstico confirmado de cáncer de mama ductal invasivo. Se evaluó la expresión de los receptores hormonales (receptor de estrógeno (RE) y de progesterona (RP)), HER2, Ki67 y GRB7, mediante inmunohistoquímica (IHQ), y a partir de estos, se clasificaron los tumores en subtipos intrínsecos. Los análisis estadísticos incluyeron las pruebas de Chi-cuadrado/test exacto de Fisher para las variables categóricas, y la prueba U Mann Whitney/ Kruskal Wallis para las variables cuantitativas. Se evaluó la supervivencia global (SG) y libre de enfermedad (SLR) según la coexpresión de HER2/GRB7 usando el método de Kaplan-Meier y el test de log-rank. Resultados. La expresión de GRB7 se observó exclusivamente en tumores HER2-positivos (luminal B/HER2+ y HER2-enriquecidos: p<0,001). Los casos HER2+/GRB7+ mostraron una mayor expresión de Ki67 (40% vs. 27,5%, p=0,029), pero una tendencia a presentar un menor tamaño tumoral (30 mm vs. 51 mm, p=0,097), comparado con los tumores HER2+/GRB7-. No obstante, no se observaron diferencias en la supervivencia según la coexpresión de HER2/GRB7 (SG: p=0,6; SLR: p=0,07). Conclusiones. En nuestra muestra de estudio, la expresión de GRB7 en tumores HER2+ no se asoció con características clínico-patológicas de pronóstico desfavorable.

Objective: To analyze differences in the presentation of clinicopathological variables according to GRB7 protein expression in HER2-positive tumors in Colombian patients with invasive ductal breast carcinomas diagnosed between 2013 and 2015 at the Instituto Nacional de Cancerología (Bogotá, Colombia).Methods: A total of 158 breast cancer patients were included with a confirmed diagnosis of invasive ductal carcinoma. A single pathologist evaluated the protein expression of hormone receptors (estrogen (ER) and progesterone receptor (PR)), HER2, Ki67, and GRB7 by immunohistochemistry (IHC). The chi-square and Fisher's exact tests were used to assess differences between categorical variables, as well as the Mann-Whitney/Kruskal-Wallis U test for numerical variables. Overall (OS) and disease-free (DFS) survival were evaluated according to HER2/GRB7 co-expression using the Kaplan-Meier method and log-rank test.Results:GRB7 expression was observed exclusively in HER2-positive tumors (luminal B/HER2+ and HER2-enriched: p<0.001). HER2+/GRB7+ cases showed higher Ki67 expression (40% vs. 27.5%, p=0.029) and a tendency to present a smaller tumor (30 mm vs. 51 mm, p=0.097) compared to HER2+/GRB7- tumors. However, no differences in OS or DFS were observed by HER2/GRB7 co-expression (OS: p=0.6; DFS: p=0.07).Conclusions:Our results in Colombian patients indicate that GRB7 expression in HER2-positive breast tumors is not associated with unfavorable clinicopathological features.

Association of genetic ancestry with HER2, GRB7 AND estrogen receptor expression among Colombian women with breast cancer.

Background: Our previous study reported higher mRNA levels of the human epidermal growth factor receptor 2 (HER2)-amplicon genes ERBB2 and GRB7 in estrogen receptor (ER)-positive breast cancer patients with relatively high Indigenous American (IA) ancestry from Colombia. Even though the protein expression of HER2 and GRB7 is highly correlated, they may also express independently, an event that could change the patients' prognosis. In this study, we aimed to explore the differences in ER, HER2 and GRB7 protein expression according to genetic ancestry, to further assess the clinical implications of this association. Methods: We estimated genetic ancestry from non-tumoral breast tissue DNA and assessed tumoral protein expression of ER, HER2, and GRB7 by immunohistochemistry in a cohort of Colombian patients from different health institutions. We used binomial and multinomial logistic regression models to test the association between genetic ancestry and protein expression. Kaplan-Meier and log-rank tests were used to evaluate the effect of HER2/GRB7 co-expression on patients' survival. Results: Our results show that patients with higher IA ancestry have higher odds of having HER2+/GRB7- breast tumors, compared to the HER2-/GRB7- subtype, and this association seems to be stronger among ER-positive tumors (ER+/HER2+/GRB7-: OR=3.04, 95% CI, 1.47-6.37, p<0.05). However, in the multivariate model this association was attenuated (OR=1.80, 95% CI, 0.72-4.44, p=0.19). On the other hand, it was observed that having a higher European ancestry patients presented lower odds of ER+/HER2+/GRB7- breast tumors, this association remained significant in the multivariate model (OR=0.36, 95% CI, 0.13 - 0.93, p= 0.0395). The survival analysis according to HER2/GRB7 co-expression did not show statistically significant differences in the overall survival and recurrence-free survival. Conclusions: Our results suggest that Colombian patients with higher IA ancestry and a lower European fraction have higher odds of ER+/HER2+/GRB7- tumors compared to ER+/HER2-/GRB7- disease. However, this association does not seem to be associated with patients' overall or recurrence-free survival.

Effect of neoadjuvant therapy on breast cancer biomarker profile.

BACKGROUND: Breast cancer clinical management requires the assessment of hormone receptors (estrogen (ER) and progesterone receptor (PR)), human epidermal growth factor receptor 2 (HER2) and cellular proliferation index Ki67, by immunohistochemistry (IHC), in order to choose and guide therapy according to tumor biology. Many studies have reported contradictory results regarding changes in the biomarker profile after neoadjuvant therapy (NAT). Given its clinical implications for the disease management, we aimed to analyze changes in ER, PR, HER2, and Ki67 expression in paired core-needle biopsies and surgical samples in breast cancer patients that had either been treated or not with NAT. METHODS: We included 139 patients with confirmed diagnosis of invasive ductal breast carcinoma from the Colombian National Cancer Institute. Variation in biomarker profile were assessed according to NAT administration (NAT and no-NAT treated cases) and NAT scheme (hormonal, cytotoxic, cytotoxic + trastuzumab, combined). Chi-squared and Wilcoxon signed-rank test were used to identify changes in biomarker status and percentage expression, respectively, in the corresponding groups. RESULTS: We did not find any significant variations in biomarker status or expression values in the no-NAT group. In cases previously treated with NAT, we did find a statistically significant decrease in Ki67 (p < 0.001) and PR (p = 0.02605) expression. When changes were evaluated according to NAT scheme, we found a significant decrease in both Ki67 status (p = 0.02977) and its expression values (p < 0.001) in cases that received the cytotoxic treatment. CONCLUSIONS: Our results suggest that PR and Ki67 expression can be altered by NAT administration, whereas cases not previously treated with NAT do not present IHC biomarker profile variations. The re-evaluation of these two biomarkers after NAT could provide valuable information regarding treatment response and prognosis for breast cancer patients.

Los ancianos ante la cercania de la muerte / The aged facing the proximity of death

El presente artículo trata algunos de los aspectos vividos por los ancianos en su proceso de envejecer y más específicamente a la hora de la muerte. Está basado en una experiencia práctica de aprendizaje, realizada en un Centro de Bienestar para el Anciano en Medellín, donde por medio de la prestación de cuidado al anciano y con una posterior revisión bibliográfica, se analizan algunas de las experiencias vividas. En él se tratan algunos aspectos relacionados con el envejecimiento y la visión que se tiene en la cultura africana y en la occidental frente al hecho de la muerte. Se definen algunas de las actitudes y sentimientos de los ancianos frente a ella, como la ansiedad y el temor; se analiza el dilema frente a la escogencia del mejor lugar para el bien morir del anciano y por último, se habla del papel del profesional de Enfermería frente a este hecho tan trascendental en la vida de todo ser humano y en especial para la del anciano.