Vessel co‐option is common in human lung metastases and mediates resistance to anti‐angiogenic therapy in preclinical lung metastasis models

Anti‐angiogenic therapies have shown limited efficacy in the clinical management of metastatic disease, including lung metastases. Moreover, the mechanisms via which tumours resist anti‐angiogenic therapies are poorly understood. Importantly, rather than utilizing angiogenesis, some metastases may instead incorporate pre‐existing vessels from surrounding tissue (vessel co‐option). As anti‐angiogenic therapies were designed to target only new blood vessel growth, vessel co‐option has been proposed as a mechanism that could drive resistance to anti‐angiogenic therapy. However, vessel co‐option has not been extensively studied in lung metastases, and its potential to mediate resistance to anti‐angiogenic therapy in lung metastases is not established. Here, we examined the mechanism of tumour vascularization in 164 human lung metastasis specimens (composed of breast, colorectal and renal cancer lung metastasis cases). We identified four distinct histopathological growth patterns (HGPs) of lung metastasis (alveolar, interstitial, perivascular cuffing, and pushing), each of which vascularized via a different mechanism. In the alveolar HGP, cancer cells invaded the alveolar air spaces, facilitating the co‐option of alveolar capillaries. In the interstitial HGP, cancer cells invaded the alveolar walls to co‐opt alveolar capillaries. In the perivascular cuffing HGP, cancer cells grew by co‐opting larger vessels of the lung. Only in the pushing HGP did the tumours vascularize by angiogenesis. Importantly, vessel co‐option occurred with high frequency, being present in >80% of the cases examined. Moreover, we provide evidence that vessel co‐option mediates resistance to the anti‐angiogenic drug sunitinib in preclinical lung metastasis models. Assuming that our interpretation of the data is correct, we conclude that vessel co‐option in lung metastases occurs through at least three distinct mechanisms, that vessel co‐option occurs frequently in lung metastases, and that vessel co‐option could mediate resistance to anti‐angiogenic therapy in lung metastases. Novel therapies designed to target both angiogenesis and vessel co‐option are therefore warranted. © 2016 The Authors. The Journal of Pathology published by John Wiley & Sons Ltd on behalf of Pathological Society of Great Britain and Ireland.     

MicroRNAs enriched in hematopoietic stem cells differentially regulate long-term hematopoietic output

The production of blood cells depends on a rare hematopoietic stem-cell (HSC) population, but the molecular mechanisms underlying HSC biology remain incompletely understood. Here, we identify a subset of microRNAs (miRNAs) that is enriched in HSCs compared with other bone-marrow cells. An in vivo gain-of-function screen found that three of these miRNAs conferred a competitive advantage to engrafting hematopoietic cells, whereas other HSC miRNAs attenuated production of blood cells. Overexpression of the most advantageous miRNA, miR-125b, caused a dose-dependent myeloproliferative disorder that progressed to a lethal myeloid leukemia in mice and also enhanced hematopoietic engraftment in human immune system mice. Our study identifies an evolutionarily conserved subset of miRNAs that is expressed in HSCs and functions to modulate hematopoietic output.     

Analysis of cytokine pattern in exhaled breath condensate of lung transplant recipients with bronchiolitis obliterans syndrome

Introduction  

Exhaled breath condensate (EBC) analysis is a promising method for investigating airway pathology. In this pilot study we tested the cytokine pattern of EBC of lung transplant patients with and without clinical evidence of bronchiolitis obliterans syndrome (BOS).     

Effect of a cytotoxic analog of LH-RH (T-98) on the growth of estrogendependent MXT mouse mammary cancers: Correlations between growth characteristics and EGF receptor content of tumors

Summary Female BDF mice bearing estrogen-dependent MXT mouse mammary cancers were treated for 4 weeks with a cytotoxic analog of luteinizing hormone-releasing hormone (LH-RH), T-98 (agonist [D-Lys⁶]LH-RH linked to glutaryl-2(hydroxymethyl)anthraquinone). The effects of T-98 were compared to those of equimolar amounts of the cytotoxic moiety 2-(hydroxymethyl)anthraquinone hemiglutarate (G-HMAQ) and carrier LH-RH agonist [D-Lys⁶]LH-RH. Both T-98 and [D-Lys⁶]LH-RH significantly inhibited the growth of MXT cancers, but G-HMAQ had only a minor non-significant effect. Cytotoxic analog T-98 and the carrier [D-Lys⁶]LH-RH had similar inhibitory hormonal activities on the pituitary-gonadal axis, but T-98 caused a larger reduction in tumor volume and decreased proliferation characteristics such as mitotic activity and AgNOR numbers in tumor cells to a greater extent than the carrier. Tumor inhibition by T-98, [D-Lys⁶]LH-RH, and ovariectomy was connected with a significant decrease in binding capacity of EGF receptors in tumor cell membranes. The concentration of EGF receptors remained high in tumors that continued to enlarge in spite of treatment and in all control untreated tumors, even those of small size. Thus, the changes in EGF receptors are likely to be the result of the therapy. Treatment with T-98 caused a greater reduction in the binding capacity of EGF receptors in tumors than [D-Lys⁶]LH-RH. This could explain the higher inhibitory effect of the cytotoxic analog on tumor growth. Since radiolabeled T-98 was shown to accumulate in MXT cancers 3 hours after a subcutaneous injection, this indicates that specific targeting might play a role in the antitumor effect exerted by this cytotoxic analog.Abbreviations LH luteinizing hormone - LH-RH LH-releasing hormone - EGF epidermal growth factor - EGF-R EGF receptor - TGF transforming growth factor - NOR nucleolar organizing region - AgNOR argyrophilic NOR - G-HMAQ 2(hydroxymethyl)anthraquinone-hemiglutarate - HPLC high performance liquid chromatography - TNF tumor necrosis factor - 5-FU 5-fluorouracil - PBS phosphate-buffered saline     

Selective increase in TNF alpha permeation across the blood-spinal cord barrier after SCI

We generated a novel mouse model of spinal cord injury (SCI) by hemisection of the right L1 lumbar spinal cord, measured the permeability of the blood-spinal cord barrier (BSCB), and tested the hypothesis that tumor necrosis factor alpha (TNF alpha) penetrates the injured BSCB by an enhanced transport system. SCI produced stereotypical sensorimotor deficits resembling the classically described Brown-Seqúard syndrome. Disruption of the BSCB was reflected by increased spinal cord uptake of radiolabeled albumin from blood; this was transient (immediately after SCI) and confined to the lumbar spinal cord. By contrast, specific increase in the entry of TNF alpha was detected in brain, cervical, thoracic, and lumbar spinal cord at 1 week after SCI, in addition to its immediate and transient increase consistent with barrier disruption. Lack of a second peak of increase in the entry of IL1 beta further supported the specificity of the TNF alpha response. Moreover, enhanced uptake of radiolabeled TNF alpha was suppressed by excess non-radiolabeled TNF alpha, indicating competition of entry via the known transport system for TNF alpha. Therefore, upregulation of the transport system after SCI probably mediates the increased permeation of TNF alpha across the BSCB. Enhanced entry of TNF alpha at 1 week after SCI was concurrent with sensorimotor and gait improvement of the mouse. We conclude that SCI by lumbar hemisection activates the transport system for TNF alpha at the BBB and suggest that selective permeation of TNF alpha may facilitate functional recovery.     

Colonic epithelial cell proliferation decreases with increasing levels of serum 25-hydroxy vitamin D.

Epidemiological evidence suggests a potential role for vitamin D in colon cancer prevention. Vitamin D, absorbed from the intestine or derived from solar ultraviolet light, is metabolized in the liver to 25-hydroxyvitamin D (25-OH D(3)). Previous studies examining effects of vitamin D upon carcinogenesis have focused upon the active metabolite 1,25-dihydroxyvitamin D [1,25-(OH)(2) D(3)], which interacts with nuclear vitamin D receptors in several organs. Until recently, the metabolism of 25-OH D(3) to 1,25-(OH)(2) D(3) was believed to occur only in the kidney, but more recent studies have shown that 25-OH D(3) conversion to 1,25-(OH)(2) D(3) can occur in other tissues. We examined the association between fasting levels of 25-OH D(3), 1,25-(OH)(2) D(3), and BsmI polymorphism of the vitamin D receptor (VDR) gene with indices of colonic epithelial cell proliferation and differentiation in a chemoprevention study, after giving vitamin D or calcium and taking rectal biopsies that were incubated with bromodeoxyuridine. Vitamin D receptor polymorphism was determined by genotyping of the 3' BsmI polymorphism in intron eight of the VDR gene. No significant changes in cell proliferation or in differentiation were found in subjects between study start and end. However, fasting serum levels of 25-OH D(3) showed a highly significant decrease with whole crypt labeling index and the size of the proliferative compartment (phi h). There was no correlation between serum levels of 1,25-(OH)(2) D(3) and the proliferative parameters. Calcium supplementation induced a significant effect upon the relationship between serum 25-OH D(3) and rectal epithelial cell labeling index and phi h when studied by covariance analysis without a relationship with 1,25-(OH)(2) D(3) levels. VDR genotype did not influence the effects of serum 25-OH D(3) or serum 1,25-(OH)(2) D(3) levels upon proliferation. These data suggest that there might be a local effect of 25-OH D(3) on colonic epithelial cells through conversion of 25-OH D(3) to 1,25-(OH)(2) D(3). Subsequent studies have demonstrated the presence of 1alpha-hydroxylase mRNA in normal colorectal epithelium and in colorectal cancer. Thus, vitamin D may have an important role in determining the effects of calcium on colorectal epithelial proliferation and may explain some of the discrepancies found previously in studies that examine the direct role of calcium on the colorectal epithelium.     

Cardiotoxicity studies with diazoxide, reserpine, guanethidine, and combinations of diazoxide and propranolol in dogs.

Diazoxide, a vasodilating antihypertensive drug, caused tachycardia when given to dogs as iv doses of 10–40 mg/kg. Doses of 20–40 mg/kg, given on 2 or 3 consecutive days, caused myocardial necroses similar to that produced by hydralazine. The papillary muscles were the primary sites of the lesion. The lesion is considered to be of ischemic origin, brought about by the exaggerated pharmacological effects. Reserpine and guanethidine, given orally in sublethal doses for 2 or 3 days, did not cause such a lesion. Propranolol, given orally in doses of 3 mg/kg two or three times daily concurrently with diazoxide, decreased the cardiotoxic effect of diazoxide but did not diminish the hypotensive effect.