Synthesis of diagnostic quality cancer pathology images by generative adversarial networks

Deep learning-based computer vision methods have recently made remarkable breakthroughs in the analysis and classification of cancer pathology images. However, there has been relatively little investigation of the utility of deep neural networks to synthesize medical images. In this study, we evaluated the efficacy of generative adversarial networks to synthesize high-resolution pathology images of 10 histological types of cancer, including five cancer types from The Cancer Genome Atlas and the five major histological subtypes of ovarian carcinoma. The quality of these images was assessed using a comprehensive survey of board-certified pathologists (n = 9) and pathology trainees (n = 6). Our results show that the real and synthetic images are classified by histotype with comparable accuracies and the synthetic images are visually indistinguishable from real images. Furthermore, we trained deep convolutional neural networks to diagnose the different cancer types and determined that the synthetic images perform as well as additional real images when used to supplement a small training set. These findings have important applications in proficiency testing of medical practitioners and quality assurance in clinical laboratories. Furthermore, training of computer-aided diagnostic systems can benefit from synthetic images where labeled datasets are limited (e.g. rare cancers). We have created a publicly available website where clinicians and researchers can attempt questions from the image survey (http://gan.aimlab.ca/). © 2020 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.

Sialyl Lewisx-P-selectin cascade mediates tumor-mesothelial adhesion in ascitic fluid shear flow

Organ-specific colonization suggests that specific cell–cell recognition is essential. Yet, very little is known about this particular interaction. Moreover, tumor cell lodgement requires binding under shear stress, but not static, conditions. Here, we successfully isolate the metastatic populations of cancer stem/tumor-initiating cells (M-CSCs). We show that the M-CSCs tether more and roll slower than the non-metastatic (NM)-CSCs, thus resulting in the preferential binding to the peritoneal mesothelium under ascitic fluid shear stress. Mechanistically, this interaction is mediated by P-selectin expressed by the peritoneal mesothelium. Insulin-like growth factor receptor-1 carrying an uncommon non-sulfated sialyl-Lewis^x (sLe^x) epitope serves as a distinct P-selectin binding determinant. Several glycosyltransferases, particularly α1,3-fucosyltransferase with rate-limiting activity for sLe^x synthesis, are highly expressed in M-CSCs. Tumor xenografts and clinical samples corroborate the relevance of these findings. These data advance our understanding on the molecular regulation of peritoneal metastasis and support the therapeutic potential of targeting the sLe^x-P-selectin cascade.

Tumor cell in the peritoneum are often exposed to shear forces generated by ascitic flow during metastasis. Here, the authors show that metastatic cancer stem cells tether more and roll slower than the non-metastatic counterparts, and that sialyl-Lewis^x -P-selectin axis mediates peritoneal metastasis.

New insights into the role of soluble E-cadherin in tumor angiogenesis

A key to successful metastasis is the formation of new vasculature, known as angiogenesis. Therefore, it is of great interest to unravel the underlying molecular mechanisms of tumor angiogenesis. Cadherins are a major class of cell surface receptors. The loss of cadherins, especially E-cadherin, is a well-established marker for tumor metastasis. Loss of E-cadherin is also a defining characteristic of several carcinomas, such as lobular carcinoma of the breast, and de-differentiated endometrioid carcinoma of the endometrium and ovary, which are known to be associated with more aggressive tumor behavior. Although E-cadherin is synthesized as a transmembrane molecule, its extracellular domain can be enzymatically cleaved off and released as a soluble E-cadherin (sE-cad), and this accounts for the loss of E-cadherin function or expression that has been implicated in tumor progression and metastasis. Importantly, sE-cad is present at high levels in the serum and malignant ascites of ovarian carcinoma patients. Nevertheless, little is known about how this essential protein dictates metastasis. Hitherto, many studies have given attention only to the dominant negative role of the loss of E-cadherin in weakening cell-cell adhesion, however, it is not known if sE-cad has biological activity in itself. In addition, the release mechanism of sE-cad has remained elusive. Here we show for the first time that sE-cad is a pivotal regulator of angiogenesis. We further show that exosomes are a novel major platform for the cleavage and release of sE-cad in vitro, in vivo and in patients’ derived samples (Nat Commun, 9: 2270).

Loss of ATRX and DAXX expression identifies poor prognosis for smooth muscle tumours of uncertain malignant potential and early stage uterine leiomyosarcoma

Uterine smooth muscle tumours of uncertain malignant potential (STUMP) are diagnostically and clinically challenging. The alternative lengthening of telomeres (ALT) telomere maintenance mechanism is associated with poor survival in soft tissue leiomyosarcoma. Time to first recurrence and survival were known for 18 STUMP and 43 leiomyosarcomata (LMS). These were screened for ALT telomere maintenance by the presence of ALT‐associated PML bodies (APBs) and for changes associated with the ALT phenotype, namely aberrant p53 expression, isocitrate dehydrogenase 1 mutation (R132H substitution) expression, mutant ATRX (αthalassemia/mental retardation syndrome X‐linked) expression and mutant DAXX (death‐domain‐associated protein) expression by immunohistochemistry (IHC). Overexpression of p16^INK4A was examined immunohistologically in a subset of cases. Many of the tumours associated with death or recurrence demonstrated APBs commensurate with ALT telomere maintenance. However, all uterine STUMP (4/4), and vaginal STUMP (2/2) patients, and almost all LMS patients (88.4%, 23/26, including 90% (9/10) of stage 1 LMS cases), who had died of disease or who had recurrent disease, displayed loss of ATRX or DAXX expression. Loss of ATRX or DAXX expression identified poor prognosis (95% CI 2.1 to 40.8, p < 0.003), in the LMS group. Thus, loss of ATRX or DAXX expression in uterine smooth muscle tumours identifies a clinically aggressive molecular subtype of early stage LMS and when histopathological features are problematic such as in STUMP. As ATRX and DAXX IHC is readily performed in diagnostic laboratories these are potentially useful for routine histopathological classification and management.

Biochemical and cytochemical studies of the lateral geniculate bodies after optic nerve ligature

The short term effect of optic nerve ligature was studied by analysing the lateral genuiclate bodies. There was significant difference in total RNA amount per unit tissue between the contralateral and ipsilateral sides 1 week after ligation. There were, however, no observable difference in the acid phosphatase activity and the quantity of contacts between the two sides. The dopamine receptors on the membranes also were much higher in number in the contralateral side.

Comparative ultrastructural study of the optic nerves and visual cortices of young (2.5 months) and old (17 months) mice

The aging optic nerves and visual cortices were studied in mice. Changes in the morphology of neuroglia were evident in the optic nerve but no difference in the numbers of neurotubules or myelin sheaths optic nerve fibers in the aged were observed. Large myelinated fibers, however, begun to degenerate. In the aging visual cortices, a higher proportion of dendrodendritic contacts were present and microglia cells were found to be active.