Abstract S6-10: Identification of a Novel Tumor Suppressor Network Reveals a Role for Proto-Oncogenic Receptor Tyrosine Kinases in Triple-Negative Breast Cancer

Breast cancer is a collection of diseases with distinct clinical behaviors and underlying genetic causes. Triple-negative breast cancer (TNBC) is a common subtype of breast cancer that confers a particularly poor prognosis and is refractory to current targeted therapies. Unfortunately, the molecular determinants driving this aggressive malignancy are poorly understood. Using an unbiased genetic screen, we have identified a novel tumor suppressor network that governs proliferation and transformation of TNBCs in vitro and in vivo. We define SECT21 as a core component in this network and a commonly inactivated tumor suppressor in TNBC. SECT21 is a potent suppressor of human mammary epithelial cell proliferation and transformation. SECT21 function is frequently compromised in human TNBCs by inactivating mutations, deletion, or loss of protein expression. Mechanistically, SECT21 is a tyrosine phosphatase that suppresses cellular transformation by interacting with and inhibiting several oncogenic receptor tyrosine kinases including HER2, EGFR, and PDGFR. Notably, the tumorigenic and metastatic potential of SECT21-deficient TNBCs is severely impaired by restoring SECT21 function or by inhibiting kinase targets of SECT21, suggesting that TNBCs are dependent on the proto-oncogenic tyrosine kinases constrained by SECT21. Collectively, these data identify SECT21 as a commonly inactivated tumor suppressor and provide a rationale for combinatorially targeting tyrosine kinases in TNBC and other cancers based on their profile of tyrosine phosphatase activity.

Citation Information: Cancer Res 2010;70(24 Suppl):Abstract nr S6-10.

Nutritive value of tropical tree leaf meals in adult sows

Tree leaf meals (TLM) are increasingly used in the tropics to feed pigs. The nutritive value of the TLM of cocoyam (Xanthosoma saggitifolium), mulberry (Morus alba) and Trichanthera gigantea, their effect on the digestive tract and their fermentation rate in the large intestine, were determined in adult sows given diets containing 150 or 300 g TLM per kg. The TLM contained from 8·5 to 12·0 MJ digestible energy per kg dry matter (DM) and from 60 to 125 g digestible protein per kg DM. The digestibility was not affected ( P>0·05) by their rate of incorporation in the diet. The apparent ileal protein digestibility of the diets containing 300 g TLM per kg was also determined by the slaughtering method. It reached 80% for the basal diet and 54, 70 and 74% for the Trichanthera-, mulberry- and cocoyam-based diets, respectively. No diet effect ( P>0·05) was observed on the weight and length of the gastro-intestinal tract, with the exception of a heavier caecum in sows given the Trichanthera-based diet ( P<0·01). The pH of the gastric fluid of these sows was also higher ( P<0·001). The fermentation of the dietary fibre in the large intestine was evaluated by the gas technique using syringes. The cocoyam leaves presented the highest amount of total gas produced after fibre fermentation ( P<0·001). The ranking order of gas production was identical to that observed for the digestibility coefficients: Trichanthera <mulberry <cocoyam. In conclusion, TLM can represent up to 0·3 of a diet for sows. Their use in sow nutrition may be considered in tropical regions where protein sources are scarce.

Effects of trendelenburg position and positive intrathoracic pressure on internal jugular vein cross-sectional area in anesthetized children

STUDY OBJECTIVE

To compare the cross-sectional area (in cm(2)) of the left internal jugular vein (LIJV) and right internal jugular vein (RIJV) in anesthetized children, and measure the response to the Trendelenburg tilt position (TBRG) and a positive inspiratory pressure hold.

DESIGN

Prospective, nonrandomized study.

SETTING

University medical center.

PATIENTS

45 ASA physical status I and II children, ages 6 months to 8 years, undergoing general anesthesia and mechanical ventilation.

INTERVENTIONS

The cross-sectional area of both internal jugular veins was measured with a 5-MHz, two-dimensional surface transducer, at the level of the cricoid cartilage. Three measurements were obtained: 1) with the patient supine, 2) during a 10-second breath-hold with a positive inspiratory pressure (PIP) of 20 cm H(2)O, and 3) with the patient at 20 degrees TBRG. Data were analyzed with two-way analysis of variance (ANOVA) and Student-Newman-Keuls test, with a p < 0.05 considered significant.

MEASUREMENTS AND MAIN RESULTS

In supine patients, the cross-sectional area of the RIJV was larger than the LIJV in 31 patients (69%), and equal or smaller in 14 patients (31%) (0.80 +/- 0.38 vs. 0.59 +/- 0.22; p = 0.002). A PIP hold, but not TBRG, significantly dilated the RIJV (0.8 +/- 0.38 at baseline vs. 0.93 +/- 0.42 with TBRG; p = not significant vs. 1.1 +/- 0.46 with PIP; p < 0.05), whereas neither maneuver was effective with the LIJV.

CONCLUSION

The cross-sectional area of the RIJV is often greater than the LIJV; the TBRG was not effective to increase the cross-sectional area of the internal jugular veins, and only a PIP hold increased significantly the cross-sectional area of the RIJV. In this study, the LIJV appeared of smaller size and less compliant compared with the RIJV.

Fulminant amebic colitis

Amebiasis is the acute and chronic disease produced by Entamoeba histolytica, an entity which occurs in endemic fashion in many of the tropical and subtropical areas of the world, capable of affecting diverse organs of the body, especially the colon. Amebiasis has different clinical forms of presentation, varying from the asymptomatic carrier state to severe, although not frequent, fulminant or necrotizing colitis, characteristically associated with high morbidity and mortality. We hereby report a series of 50 adult patients with fulminating amebic colitis managed at our institution between January, 1971 and July, 1989, with a global mortality of 60%. Early diagnosis, treatment with effective antiamebic agents--specifically metronidazole--and opportune aggressive surgical intervention have resulted in better survival rates. We had no survivors prior to 1970; our current survival rate is still a dismal 40%, indicating the very severe nature of the disease.

Partial cognitive-dysmnesic seizures as a model for studying psychosis

Nineteen patients were analyzed who exhibited cognitive-dysmnesic psychic partial seizures and structural damage shown by means of CT scans. It was observed that these seizures originated in the amygdala-hippocampal system, coinciding with the effects found when using electrical stimulation of the brain. An attempt is made to relate these findings to the present biochemical hypotheses of schizophrenia, the kindling effect and the genetico-maturational hypotheses. All these data seem to agree and point in the direction of the possible neurophysiological mechanisms of psychosis and of schizophrenia in particular.

Palinopsia and visual allesthesia

Two cases of palinopsia are reported. The first patient had palinopsia and visual allesthesia secondary to an occipital calcified cysticercus. Symptoms were more prominent during treatment for his parasitic infection. The second case was a patient with long standing vascular headaches associated for many years with episodes of visual persistence; he had a right occipital lobe infarct; he reported deformation of images, illusion of movement and macropsia in his left homonymous hemianoptic visual field. Different hypotheses for explaining palinopsia have been proposed. An analysis of our cases does not prove or disprove any of the current hypotheses. However, the current hypotheses do not necessarily contradict each other. Implications of the two cases reported are analyzed.