microRNA

Type 2 Diabetes and MicroRNA Link Uncovered

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Previous studies, mostly in animal models, have suggested that microRNAs (miRNAs) play a role in type 2 diabetes (T2D). However, there is limited knowledge of miRNA expression in human pancreatic islets (HPIs). Now, researchers at Cornell University, the University of Cambridge, and the National Human Genome Research Institute (NHGRI) of the National Institutes of Health (NIH) have identified which miRNAs are associated with the disease in humans. The findings represent the largest study to date of diabetes-linked miRNAs found in human pancreatic islets.

The new study is published in Proceedings of the National Academy of Sciences in a paper titled, “Human pancreatic islet microRNAs implicated in diabetes and related traits by large-scale genetic analysis.”

“Genetic studies have identified ≥240 loci associated with the risk of T2D, yet most of these loci lie in noncoding regions, masking the underlying molecular mechanisms,” wrote the researchers. “Recent studies investigating mRNA expression in human pancreatic islets have yielded important insights into the molecular drivers of normal islet function and T2D pathophysiology. However, similar studies investigating miRNA expression remain limited. Here, we present data from 63 individuals, the largest sequencing-based analysis of miRNA expression in human islets to date.”

The study’s corresponding authors, Praveen Sethupathy, PhD, professor of biomedical sciences in the College of Veterinary Medicine and director of the Center for Vertebrate Genomics at Cornell University, and Francis Collins, MD, PhD, former director of the NIH and a senior investigator at the National Human Genome Research Institute at the NIH, had access to a network that supplied nearly 65 human pancreatic islet samples from cadavers for this study.

“We’ve defined in the largest cohort of human islets to date the miRNAs that might be most relevant for type 2 diabetes,” said Sethupathy, who was a postdoctoral researcher in Collins’ NIH lab from 2008–2011.

“We [also] found that some of the diabetes-associated miRNAs in humans are not ones that have been well-characterized in the previous two decades of studying islets and diabetes in rodent models,” he said.

“There’s been long-standing interest to better understand the molecular environment of the pancreas so that we could get a better handle on what goes awry in diabetes patients and then eventually be able to use that information to develop better therapeutics,” Sethupathy explained.

The relatively large sample size helps to reveal the extent of variation in the quantity of miRNAs in the islets, or expression level, across the human population. The researchers also had genetic information on all the patients, which helped them determine a handful of genomic loci underlying variability in miRNA expression, though ultimately this type of inquiry will require many hundreds of samples for a fuller picture. One of these loci was found in the same area of the genome that is associated with T2D-related traits, which could suggest a novel mechanism for how T2D develops.

Some of the most altered miRNAs in islets from individuals with T2D were consistent with those found in previous rodent studies, but there were also some notable differences. “These represent interesting candidates to investigate further in human models of pancreatic islets,” Sethupathy said.

Looking toward the future, the researchers will need to further invest in the development and study of human models of T2D, such as genetically-modified islets or organoids.

Novel risk classifier could facilitate earlier prediction of thyroid cancer recurrence

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A risk model based on combinatorial messenger RNA and microRNA expression has potential clinical utility as a prognostic indicator of thyroid cancer recurrence, according to researchers.

The findings could facilitate earlier prediction of thyroid cancer recurrence, offering clinicians the ability to improve patient outcomes by tailoring treatment to disease risk and increasing posttreatment surveillance, Hannah R. Nieto, MBBS, MRCS, PhD, an academic clinical lecturer at the Institute of Metabolism and Systems Research at the University of Birmingham, United Kingdom, and colleagues, wrote in The Journal of Clinical Endocrinology & Metabolism.

Next-generation sequencing revealed more than 100 new biomarkers linked to thyroid cancer recurrence. Data were derived from Nieto HR, et al. J Clin Endocrinol Metab. 2021;doi:10.1210/clinem/dgab836.

Clinicians currently predict risk for thyroid cancer recurrence using clinical tools that often restage patients after their cancer treatment, according to the study background.

The strategy is useful in stratifying patients to the level of follow-up and degree of thyroid-stimulating hormone suppression required postoperatively; however, it does not inform the surgeon and patient about risk for recurrence until after all treatment has been completed.

“Understanding which thyroid carcinomas are going to recur, and the functional reasons behind the recurrence, will be key to improving patient care,” the researchers wrote.

Nieto and colleagues analyzed data from The Cancer Genome Atlas (TCGA) to identify differentially expressed genes (mRNA/microRNA) in 46 recurrent vs. 455 nonrecurrent thyroid tumors. Two exonic mutational pipelines were used to identify somatic mutations. Functional gene analysis was performed in cell-based assays in multiple thyroid cell lines. The prognostic value of genes was evaluated with TCGA data sets.

Researchers identified 128 new potential biomarkers associated with recurrence, including 40 messenger RNAs (mRNAs), 39 microRNAs and 59 genetic variants. Among differentially expressed genes, modulation of fibronectin 1 (FN1), integrin alpha-3 (ITGalpha3) and MET proto-oncogene receptor tyrosine kinase (MET) had a “significant impact” on thyroid cancer cell migration.

Similarly, researchers observed ablation of miR-486 and miR-1179 increased migration of TPC-1 and SW1736 cells.

Researchers further utilized genes with a validated functional role and identified a five-gene risk score classifier as an independent predictor of thyroid cancer recurrence. After controlling for age, sex, disease stage, tumor stage and node status, multivariate analysis showed that the five-gene risk score classifier was the sole independent prognostic factor for the entire group of THCA patients.

“With the limited treatment options available, early prediction of recurrent disease should impact favorably on patient outcomes by tailoring treatment to disease risk and increasing posttreatment recurrence surveillance,” the researchers wrote. “Our data suggest that the expression of genes FN1, ITGalpha3, MET, miR-486 and miR-1179 can be useful future prognostic tools in indicating the likelihood of individual papillary thyroid cancer recurrence.”

PERSPECTIVE

BACK TO TOP Angela M. Leung , MD, MSc)

Angela M. Leung, MD

As the authors note, current recommendations do not advise the molecular profiling of thyroid cancers at the time of their initial evaluation. For these prognostic data to be impactful, the time and substantial costs involved to send off molecular markers for every thyroid nodule or thyroid cancer need to be worked out.

These data are helpful in adding to the understanding of which molecular drivers are important for thyroid cancers and help inform why we sometimes see such a wide difference in disease persistence/recurrence rates despite similar tumor and patient characteristics. 

Angela M. Leung, MD

Associate Professor of Medicine

Division of Endocrinology, Diabetes, and Metabolism

Department of Medicine

UCLA David Geffen School of Medicine

VA Greater Los Angeles Healthcare System

Keratin 19: a key role player in the invasion of human hepatocellular carcinomas.

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Abstract

Objective Keratin (K)19, a biliary/hepatic progenitor cell (HPC) marker, is expressed in a subset of hepatocellular carcinomas (HCC) with poor prognosis. The underlying mechanisms driving this phenotype of K19-positive HCC remain elusive.

Design Clinicopathological value of K19 was compared with EpCAM, and α-fetoprotein, in a Caucasian cohort of 242 consecutive patients (167 surgical specimens, 75 needle biopsies) with different underlying aetiologies. Using microarrays and microRNA profiling the molecular phenotype of K19-positive HCCs was identified. Clinical primary HCC samples were submitted to in vitro invasion assays and to side population analysis. HCC cell lines were transfected with synthetic siRNAs against KRT19 and submitted to invasion and cytotoxicity assays.

Results In the cohort of surgical specimens, K19 expression showed the strongest correlation with increased tumour size (p<0.01), decreased tumour differentiation (p<0.001), metastasis (p<0.05) and microvascular invasion (p<0.001). The prognostic value of K19 was also confirmed in a set of 75 needle biopsies. Profiling showed that K19-positive HCCs highly express invasion-related/metastasis-related markers (eg, VASP, TACSTD2, LAMB1, LAMC2, PDGFRA), biliary/HPC markers (eg, CD133, GSTP1, NOTCH2, JAG1) and members of the miRNA family 200 (eg, miR-141, miR-200c). In vitro, primary human K19-positive tumour cells showed increased invasiveness, and reside in the chemoresistant side population. Functionally, K19/KRT19 knockdown results in reduced invasion, loss of invadopodia formation and decreased resistance to doxorubicin, 5-fluorouracil and sorafenib.

Conclusions Giving the distinct invasive properties, the different molecular profile and the poor prognostic outcome, K19-positive HCCs should be considered as a seperate entity of HCCs.

Source: BMJ

New test enables early diagnosis of liver cancer.

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Scientists, including Indian-origin researchers, have developed a new test that can distinguish early liver cancer cells from nearly identical normal liver cells by giving them a distinctive red-brown hue.

The inability to definitively tell the difference between them often means the disease is detected late when treatment options are less effective, said Dr Ravindra Kolhe, pathologist and Medical Director of the Georgia Esoteric, Molecular Labs at the Medical College of Georgia at Georgia Regents University.

“There is no definitive test for early diagnosis of liver cancer. Our test adds a level of comfort for making the diagnosis,” said Kolhe, lead author of the study. Early liver cancer is mostly silent. By the time it’s large enough to cause classic symptoms such as abdominal pain and weight loss, the cancer cells look distinctive but the liver is failing.

The myriad of treatment options – from removing the diseased portion of the liver to liver transplants to freezing or heating cancer cells – have a high chance of failing as well, Kolhe said.

Kolhe began collaborating with BioGenex laboratories, a California company with expertise in cell and tissue testing, to develop a probe that gives cancer cells the distinctive red-brown hue.

The probe detects and stains a microRNA called mir-21, which is found in liver cancer but not healthy liver cells, Kolhe said. Unlike RNA, microRNA doesn’t make proteins rather helps control proteins that are expressed by RNA. That means it’s more stable and can survive harsh chemicals normally used to prepare the biopsy for microscopic evaluation.

For the study, they used their probe on biopsies of 10 healthy livers and 10 livers with early cancers. In every case of liver cancer, the biopsy took on the red-brown hue. The probe was not detected in normal cells. The studies were done retrospectively, so they already knew which patients ultimately were diagnosed with cancer. They are now using the test on 200 similar cases of liver cancer.

Treatment of HCV Infection by Targeting MicroRNA

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BACKGROUND

The stability and propagation of hepatitis C virus (HCV) is dependent on a functional interaction between the HCV genome and liver-expressed microRNA-122 (miR-122). Miravirsen is a locked nucleic acid–modified DNA phosphorothioate antisense oligonucleotide that sequesters mature miR-122 in a highly stable heteroduplex, thereby inhibiting its function.

METHODS

In this phase 2a study at seven international sites, we evaluated the safety and efficacy of miravirsen in 36 patients with chronic HCV genotype 1 infection. The patients were randomly assigned to receive five weekly subcutaneous injections of miravirsen at doses of 3 mg, 5 mg, or 7 mg per kilogram of body weight or placebo over a 29-day period. They were followed until 18 weeks after randomization.

RESULTS

Miravirsen resulted in a dose-dependent reduction in HCV RNA levels that endured beyond the end of active therapy. In the miravirsen groups, the mean maximum reduction in HCV RNA level (log10 IU per milliliter) from baseline was 1.2 (P=0.01) for patients receiving 3 mg per kilogram, 2.9 (P=0.003) for those receiving 5 mg per kilogram, and 3.0 (P=0.002) for those receiving 7 mg per kilogram, as compared with a reduction of 0.4 in the placebo group. During 14 weeks of follow-up after treatment, HCV RNA was not detected in one patient in the 5-mg group and in four patients in the 7-mg group. We observed no dose-limiting adverse events and no escape mutations in the miR-122 binding sites of the HCV genome.

CONCLUSIONS

The use of miravirsen in patients with chronic HCV genotype 1 infection showed prolonged dose-dependent reductions in HCV RNA levels without evidence of viral resistance.

Source: NEJM

 

 

microRNA May Regulate Growth of Tumor Blood Vessels

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The growth of blood vessels that supply tumors with essential nutrients may be regulated in endothelial cells by a small RNA molecule, or microRNA, a new study suggests. Researchers identified a microRNA called miR-132 that appears to act as a molecular switch for endothelial cell growth, causing the cells to transition out of their normal resting state and form new blood vessels (angiogenesis). The study, which could lead to a strategy for preventing angiogenesis and potentially for treating cancer, was published online by Dr. David Cheresh of the University of California, San Diego, and his colleagues August 1 in Nature Medicine.

Endothelial cells are among the least proliferative types of cells in adults, but they can be activated in response to certain cues, such as growth factors. Suspecting that microRNAs, which are known to regulate genes, might play a role, the researchers profiled microRNAs in a stem cell model of human vascular development and identified miR-132 as highly upregulated during the development of blood vessels. They then confirmed that miR-132 expression was also highly elevated in benign lesions of blood vessels, or hemangiomas, and in the blood vessels of human tumors, but was not detectable in normal blood vessels.

A molecular pathway analysis revealed that miR-132 suppresses the expression of a gene that encodes the protein p120RasGAP, which is a negative regulator of the protein Ras. Ras is frequently altered in cancer, so targeting miR-132 could be a way to intervene in an important pathway, the researchers said. And because miR-132 is found primarily in endothelial cells, these strategies would likely be specific to these cells, they noted.

As a proof of principle, the researchers used nanoparticle technologies they have developed to deliver an inhibitor of miR-132 directly to the vasculature of tumor-bearing mice. This treatment resulted in the blockade of tumor angiogenesis and tumor growth. Moreover, in mice with retinal disease that featured the growth of new blood vessels, direct injection of the anti-miR-132 into the eye was able to suppress angiogenesis in the retina.

“We essentially turned off the angiogenic switch during angiogenesis,” said Dr. Cheresh. The preponderance of growth in these cells was reduced, making it feasible to apply this kind of approach to patients with cancer and retinal diseases characterized by extensive angiogenesis, he added.

source:NCI