Shushan Rana

Stathmin 1: a novel therapeutic target for anticancer activity

Stathmin 1 (STMN1), also known as p17, p18, p19, 19K, metablastin, oncoprotein 18, LAP 18 and Op18, is a 19 kDa cytosolic protein. It was the first discovered member of a family of phylogenetically related microtubule-destabilizing phosphoproteins critically involved in the construction and function of the mitotic spindle. A threshold level of STMN1 is required for orderly progression through mitosis in a variety of cell types. STMN1 is overexpressed across a broad range of human malignancies (leukemia, lymphoma, neuroblastoma; ovarian, prostatic, breast and lung cancers and mesothelioma). It is also upregulated in normally proliferating cell lines but is only rarely upregulated in nonproliferating cell lines with the exception of neurons, anterior pituitary cells and glial cells. Its expression is also upregulated in hepatocytes during regeneration and in lymphoid cells when they are signaled to proliferate. In this review, we summarize available data as rationale for the therapeutic manipulation of STMN1 in cancer patients.

Temporal Differences in MicroRNA Expression Patterns in Astrocytes and Neurons after Ischemic Injury

MicroRNAs (miRNAs) are small, non-protein-coding RNA molecules that modulate gene translation. Their expression is altered in many central nervous system (CNS) injuries suggesting a role in the cellular response to stress. Current studies in brain tissue have not yet described the cell-specific temporal miRNA expression patterns following ischemic injury. In this study, we analyzed the expression alterations of a set of miRNAs in neurons and astrocytes subjected to 60 minutes of ischemia and collected at different time-points following this injury. To mimic ischemic conditions and reperfusion in vitro, cortical primary neuronal and astrocytic cultures prepared from fetal rats were first placed in oxygen and glucose deprived (OGD) medium for 60 minutes, followed by their transfer into normoxic pre-conditioned medium. Total RNA was extracted at different time-points after the termination of the ischemic insult and the expression levels of miRNAs were measured. In neurons exposed to OGD, expression of miR-29b was upregulated 2-fold within 6 h and up to 4-fold at 24 h post-OGD, whereas induction of miR-21 was upregulated 2-fold after 24 h when compared to expression in neurons under normoxic conditions. In contrast, in astrocytes, miR-29b and miR-21 were upregulated only after 12 h. MiR-30b, 107, and 137 showed expression alteration in astrocytes, but not in neurons. Furthermore, we show that expression of miR-29b was significantly decreased in neurons exposed to Insulin-Like Growth Factor I (IGF-I), a well documented neuroprotectant in ischemic models. Our study indicates that miRNAs expression is altered in neurons and astrocytes after ischemic injury. Furthermore, we found that following OGD, specific miRNAs have unique cell-specific temporal expression patterns in CNS. Therefore the specific role of each miRNA in different intracellular processes in ischemic brain and the relevance of their temporal and spatial expression patterns warrant further investigation that may lead to novel strategies for therapeutic interventions.

Colorectal Cancer Liver Metastasis: Evolving Paradigms and Future Directions

In patients with colorectal cancer (CRC) that metastasizes to the liver, there are several key goals for improving outcomes including early detection, effective prognostic indicators of treatment response, and accurate identification of patients at high risk for recurrence. Although new therapeutic regimens developed over the past decade have increased survival, there is substantial room for improvement in selecting targeted treatment regimens for the patients who will derive the most benefit. Recently, there have been exciting developments in identifying high-risk patient cohorts, refinements in the understanding of systemic vs localized drug delivery to metastatic niches, liquid biomarker development, and dramatic advances in tumor immune therapy, all of which promise new and innovative approaches to tackling the problem of detecting and treating the metastatic spread of CRC to the liver. Our multidisciplinary group held a state-of-the-science symposium this past year to review advances in this rapidly evolving field. Herein, we present a discussion around the issues facing treatment of patients with CRC liver metastases, including the relationship of discrete gene signatures with prognosis. We also discuss the latest advances to maximize regional and systemic therapies aimed at decreasing intrahepatic recurrence, review recent insights into the tumor microenvironment, and summarize advances in noninvasive multimodal biomarkers for early detection of primary and recurrent disease. As we continue to advance clinically and technologically in the field of colorectal tumor biology, our goal should be continued refinement of predictive and prognostic studies to decrease recurrence after curative resection and minimize treatment toxicity to patients through a tailored multidisciplinary approach to cancer care.

MicroRNAs in Cancer: challenges and opportunities in early detection, disease monitoring, and therapeutic agents.

Purpose of ReviewThe goals of this review are to examine the usefulness of microRNAs (miRNAs) as diagnostic and prognostic biomarkers for cancer and to evaluate the applicability of miRNAs as cancer therapeutics.Recent FindingsExamination of miRNA milieu from body fluids offers a new alternative for quick, affordable, and easy analysis of disease status in patients. Blood-based exosomal miRNAs have increased stability and are an excellent choice for clinical cancer diagnostics and prognostics. Currently, there are many miRNA signatures associated with cancer and progression but there is no consensus among multiple serum and tumor sample studies. Off-target and immunological effects remain an obstacle for the use of miRNAs as novel chemotherapeutics in the clinic. Recent developments in nanotechnology and drug delivery systems which target the tumor microenvironment may provide an alternative therapeutic approach with decreased toxicity.SummaryThis review critically evaluates the literature investigating the use of miRNAs as biomarkers and their future as potential therapeutics.

Understanding and Resetting Radiation Sensitivity in Rectal Cancer

Objective: The aim of the study was to explore specific microRNAs (miRs) in rectal cancer that would predict response to radiation and identify target pathways that may be exploited for neoadjuvant therapies. Summary Background Data: Chemoradiotherapy (CRT) response is a predictor of survival in rectal cancer. Studies have demonstrated changes in RNA expression correlate with chemoradiation sensitivity across cancers. Methods: Forty-five rectal cancer patients, partial responders (PR = 18), nonresponders (NR = 13), and complete responders (CR = 14) to CRT, as defined by a tumor regression score, were examined. miRs differentially expressed, using NanoString microArray profiling, were validated with qPCR. We quantified 1 miR and its downstream targets in patient samples. Chemosensitivity was measured in HCT-116, a human colorectal carcinoma cell line, using inhibitors of SHP2 and RAF. Results: miR-451a, 502-5p, 223-3p, and 1246 were the most upregulated miRs (>1.5-fold change) in a NanoString profiling miR panel. qPCR revealed a decrease in expression of miR-451a in NRs. EMSY and CAB39, both downstream targets of miR-451a and involved in carcinogenesis (shown in TCGA) were increased in NRs (qPCR). Both targets are associated with worse survival in colorectal cancer. Inhibition of miR-451a in HCT-116 cells significantly decreased cell proliferation with treatment of SHP2 and RAF inhibitors. Conclusions: An integrated analysis of rectal cancer miRs may yield biomarkers of radioresistance and offer treatment targets for resensitization.

Differential regulation of microRNA-15a by radiation affects angiogenesis and tumor growth via modulation of acid sphingomyelinase

Activation of acid sphingomyelinase (SMPD1) and the generation of ceramide is a critical regulator of apoptosis in response to cellular stress including radiation. Endothelial SMPD1 has been shown to regulate tumor responses to radiation therapy. We show here that the SMPD1 gene is regulated by a microRNA (miR), miR-15a, in endothelial cells (ECs). Standard low dose radiation (2 Gy) upregulates miR-15a and decreases SMPD1 levels. In contrast, high dose radiation (10 Gy and above) decreases miR-15a and increases SMPD1. Ectopic expression of miR-15a decreases both mRNA and protein levels of SMPD1. Mimicking the effects of high dose radiation with a miR-15a inhibitor decreases cell proliferation and increases active Caspase-3 & 7. Mechanistically, inhibition of miR-15a increases inflammatory cytokines, such as IP10, activates caspase-1 inflammasome and increases Gasdermin D, an effector of pyroptosis. Importantly, both systemic and vascular-targeted delivery of miR-15a inhibitor decreases angiogenesis and tumor growth in a CT26 murine colorectal carcinoma model. Taken together, our findings highlight a novel role for miR mediated regulation of SMPD1 during radiation responses and establish proof-of-concept that this pathway can be targeted with a miR inhibitor.

MicroRNA-451a regulates colorectal cancer radiosensitivity

Colorectal cancer (CRC) is a leading cause of cancer-related death. The responses of CRC to standard of care adjuvant therapies such as radiation or chemotherapy are poorly understood. MicroRNAs (miRs) are small non-coding RNAs that affect gene expression programs in cells by downregulating specific mRNAs. In this study, we discovered a set of microRNAs upregulated rapidly in response to a single 2 Gy dose fraction of γ-radiation in a mouse colorectal carcinoma xenograft model. The most upregulated candidate in our signature, miR-451a inhibits tumor cell proliferation and attenuated surviving fraction in longer-term cultures. Conversely, inhibition of miR-451a increased proliferation, tumorsphere formation and surviving fraction of tumor cells. Using a bioinformatics approach, we identified four genes-CAB39, EMSY, MEX3C and EREG as targets of miR-451a. Transfection of miR-451a decreased both mRNA and protein levels of these targets. Importantly, we found miR-451a expression was decreased with tumor stage in a small subset of CRC patients. Finally, analysis of a TCGA colorectal cancer dataset reveals that the CAB39 and EMSY are upregulated at the protein level in a significant number of CRC patients and correlates with poorer overall survival. Taken together, our data indicates miR-451a influences the radiation sensitivity of colorectal carcinomas.

Gray Zone Coping with Knife: Post-operative Management of Nodular Lymphocyte Predominant Hodgkin Lymphoma

A 47-year-old woman presented to her primary care physician with right arm pain and paresthesias, prompting cervical magnetic resonance imaging. Imaging revealed C6-7 spinal stenosis and an incidental T2 hyperintense left thyroid nodule measuring 1.9 cm (Fig. 1). A neck ultrasound scan revealed a 3.2 2.8 cm spongiform left thyroid nodule and a 0.7 0.6mm inferior right isthmus nodule. Fine needle aspiration of the left thyroid nodule demonstrated abundant mixed lymphoid cells. The patient underwent left hemithyroidectomy with pathology showing a 2.2 2.0-cm nodular lymphocyte predominant Hodgkin lymphoma (Fig. 2). The posterior and inferior surgical margins were negative but less than 0.1 mm from the inked margin. Postoperative positron emission tomographyecomputed tomography demonstrated no evidence of residual locoregional or distant disease.

Abstract 829: MicroRNA regulation of radiation sensitivity in colorectal cancer

Background Patients with locally advanced rectal cancer receive neoadjuvant chemoradiation therapy (CRT) and subsequent surgery. While 10-25% of patients have complete response to CRT, the remaining patients undergo extensive tumor excision resulting in significant quality of life issues. Response to CRT is an independent predictor of overall survival highlighting the importance of improving CRT response rates. Several tumor intrinsic factors govern responses to CRT including specific gene expression programs. Emerging evidence suggests that microRNAs (miRs) modulate gene expression programs in response to radiation and have been implicated in several pathological processes associated with colorectal cancer progression. In this context, we hypothesized that differential expression of miRs regulates colorectal cancer radiation sensitivity and can be used as a biomarker to predict radiation efficacy. Methods To investigate the differences in miR profiles between rectal cancer patients that had either a pathological partial response (PR) or no response (NR), we isolated RNA from FFPE biopsies using the miRvana microRNA isolation kit (Life Technologies). We used the Nanostring miR profiling platform and obtained absolute counts for >700 human miRs. We performed in vitro gain and loss of studies with candidate miR transfections in human CRC cell lines and used a luminescence-based assay for proliferation (Cell titer glo, Promega). Surviving fraction assays were performed by seeding cells and counting colonies stained with Crystal Violet. Eight distinct miR bioinformatic target prediction algorithms initiated miR target identification, and a RISC-Trap assay was implemented to confirm miR-target interactions. The Cancer Genome Atlas (TCGA) datasets were accessed to acquire provisional survival data on 639 colorectal adenocarcinoma patients. Results We identified 17 miRs that were differentially expressed, and miR-451a, among the most upregulated miRs, inhibited proliferation and colony formation in 2D and 3D assays in the presence of radiation. Target prediction algorithms highlighted CAB39, EMSY, EREG, and MEX3C as prominent miR-451a targets in colorectal cancer and/or radiation. TCGA subset anaylsis found CAB39 and EMSY protein levels were found to be upregulated in 14% and 6% of cases, respectively, and upregulated co-expression of these genes significantly reduced 3 year overall survival (69% vs 78%, p Conclusions miRs alter cell survival networks affecting radiation sensitivity and serve to identify pathways amenable to alternative therapeutic modulation Citation Format: Shushan Rana, Katherine Kelley, Rebecca Ruhl, Charles Thomas, Liana Tsikitis, Sudarshan Anand. MicroRNA regulation of radiation sensitivity in colorectal cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 829. doi:10.1158/1538-7445.AM2017-829