Molecular Characterization of Differentiated-Resistance MSC Subclones by Single-Cell Transcriptomes

Background: The mechanism of tumorigenicity potentially evolved in mesenchymal stem cells (MSCs) remains elusive, resulting in inconsistent clinical application efficacy. We hypothesized that subclones in MSCs contribute to their tumorgenicity, and we approached MSC-subclones at the single-cell level.

Methods: MSCs were cultured in an osteogenic differentiation medium and harvested on days 12, 19, and 25 for cell differentiation analysis using Alizarin Red and followed with the single-cell transcriptome.

Results: Single-cell RNA-seq analysis reveals a discrete cluster of MSCs during osteogenesis, including differentiation-resistant MSCs (DR-MSCs), differentiated osteoblasts (DO), and precursor osteoblasts (PO). The DR-MSCs population resembled cancer initiation cells and were subjected to further analysis of the yes associated protein 1 (YAP1) network. Verteporfin was also used for YAP1 inhibition in cancer cell lines to confirm the role of YAP1 in MSC--involved tumorigenicity. Clinical data from various cancer types were analyzed to reveal relationships among YAP1, OCT4, and CDH6 in MSC--involved tumorigenicity. The expression of cadherin 6 (CDH6), octamer-binding transcription factor 4 (OCT4), and YAP1 expression was significantly upregulated in DR-MSCs compared to PO and DO. YAP1 inhibition by Verteporfin accelerated the differentiation of MSCs and suppressed the expression of YAP1, CDH6, and OCT4. A survey of 56 clinical cohorts revealed a high degree of co-expression among CDH6, YAP1, and OCT4 in various solid tumors. YAP1 inhibition also down-regulated HeLa cell viability and gradually inhibited YAP1 nuclear localization while reducing the transcription of CDH6 and OCT4.

Conclusions: We used single-cell sequencing to analyze undifferentiated MSCs and to discover a carcinogenic pathway in single-cell MSCs of differentiated resistance subclones.

Single-cell transcriptomes reveal the mechanism for a breast cancer prognostic gene panel

The clinical benefits of the MammaPrint® signature for breast cancer is well documented; however, how these genes are related to cell cycle perturbation have not been well determined. Our single-cell transcriptome mapping (algorithm) provides details into the fine perturbation of all individual genes during a cell cycle, providing a view of the cell-cycle-phase specific landscape of any given human genes. Specifically, we identified that 38 out of the 70 (54%) MammaPrint® signature genes are perturbated to a specific phase of the cell cycle. The MammaPrint® signature panel derived its clinical prognosis power from measuring the cell cycle activity of specific breast cancer samples. Such cell cycle phase index of the MammaPrint® signature suggested that measurement of the cell cycle index from tumors could be developed into a prognosis tool for various types of cancer beyond breast cancer, potentially improving therapy through targeting a specific phase of the cell cycle of cancer cells.

Precision Medicine in Pediatric Neurooncology: A Review

Central nervous system tumors are the leading cause of cancer related death in children. Despite much progress in the field of pediatric neurooncology, modern combination treatment regimens often result in significant late effects, such as neurocognitive deficits, endocrine dysfunction, secondary malignancies, and a host of other chronic health problems. Precision medicine strategies applied to pediatric neurooncology target specific characteristics of individual patients' tumors to achieve maximal killing of neoplastic cells while minimizing unwanted adverse effects. Here, we review emerging trends and the current literature that have guided the development of new molecularly based classification schemas, promising diagnostic techniques, targeted therapies, and delivery platforms for the treatment of pediatric central nervous system tumors.

Pediatric malignant germ cell tumors: A comparison of the neuro-oncology and solid tumor experience

Malignant germ cell tumors (GCT) arise from abnormal migration of primordial germ cells and are histologically identical whether they occur inside or outside the central nervous system (CNS). However, the treatment strategy for GCTs varies greatly depending on the location of the tumor. These differences are in part due to the increased morbidity of surgery in the CNS but may also reflect differential sensitivity of the tumors to chemotherapy and radiation therapy (RT) or not-yet-understood biologic differences between these tumors. Historically, specialists caring for extracranial and intracranial GCT in the United States have practiced separately without much cross communication. The focus of this review is a discussion of differences between the management of CNS and extra-CNS GCTs and opportunities for collaboration and future research.

Plasmacytoma-like post-transplant lymphoproliferative disorder seen in pediatric combined liver and intestinal transplant recipients

Post-transplant lymphoproliferative disease (PTLD) is a lymphoproliferative disorder secondary to chronic immunosuppression and is the most common malignancy in transplanted patients [Kamdar et al. Curr Opin Organ Transplant, 2011; 16:274-280]. Although PTLD usually presents as B or T cell lymphoma, plasmacytomas have been reported, mostly in the adult population. Six cases of pediatric plasmacytoma-like PTLD have been reported, all of which were treated with vincristine, adriamycin, and dexamethasone (VAD), high dose dexamethasone alone, or dexamethasone + thalidomide [Tcheng et al. Pediatric Blood Cancer, 2006; 47:218-223; Perry et al. Blood, 2013; 8:1377-1383]. We present two cases of pediatric plasmacytoma-like PTLD in combined liver and small bowel transplant patients both successfully treated with bortezomib and dexamethasone based on multiple myeloma protocols [Kyle and Rajkumar, Clin Lymphoma Myeloma, 2009; 9:278-288; Adams and Kaufmann, Cancer Invest, 2004; 22:304-311].