MicroRNAs in personalized cancer therapy

MicroRNAs (miRNAs) are small endogenous noncoding single-stranded RNAs. They critically regulate the post-transcriptional activity of several key physiological and pathological cell processes including cancer. Through their transcriptional regulatory functions, miRNAs control tumor proliferation, invasion and metastasis. The expression of miRNAs is altered in malignancies. It could be either upregulated or downregulated depending upon the role of a particular miRNA in the pathogenetic development of the tumor. The upregulated miRNAs exert an 'oncogenic' effect leading to tumor proliferation and metastasis. The downregulated miRNAs have 'tumor suppressor' effects. Recent studies have demonstrated that miRNAs have a role in the early diagnosis, prognosis and treatment outcome assessment of cancers. Every tumor has specific miRNA alterations, i.e. some are overexpressed and others are downregulated. These altered miRNAs can be used as a tumor-specific 'signature' for potential clinical use in improving the accuracy of diagnosis, determining prognosis and as therapeutic targets for therapy. Specific miRNAs can be targeted using oligonucleotide sequences corresponding to the altered miRNAs. These are referred to as 'antagomirs'. Depending upon the miRNA alterations in the tumor of an individual patient, one could design targeted therapies for personalized medicine in patients. Hence, miRNAs have an immense role in personalized cancer therapy.

Abstract P4-15-07: MicroRNA signature of breast cancer brain metastasis for novel targeted therapies

Rationale:

MicroRNAs (miRNAs) are recently described novel small non-coding endogenous RNAs which critically regulate cancer progression, invasion and metastasis. Altered expression of miRNAs has been proposed to control the invasive capability of cancer cells. Modulating altered miRNAs is a novel approach for targeted therapy for cancer. Breast cancer is the most common cancer among women in the US. Breast cancer-related mortality and morbidity are primarily due to metastatic disease especially brain metastasis which also impacts patients’ quality of life. Molecular mechanisms of brain metastasis of breast cancer are largely unknown.

Study Objectives:

Identifying molecular miRNA signatures in breast cancers which metastasize to the brain can assist in designing novel targeted therapies to prevent and eliminate brain metastasis.

Design:

RNA was extracted from formalin fixed paraffin embedded tumor tissues from a cohort of breast cancer patients with brain metastasis, and age, stage and follow-up matched breast cancer cases without brain metastasis. miRNA expression profiling was done using EQIXON microarray. Quantitative real-time PCR (qRT-PCR) was used to validate abnormal expression of miRNAs. Data was statistically analyzed using Kruskal-Wallis test to determine the clinical significance of the findings.

Results:

Over 2000 unique miRNA sequences were profiled in each case. The upregulated miRNAs included miR-3927-5p, miR-216b and miR-10b and the down regulated miRNAs were miR-4280, miR-3174 and miR-1244 and miR20b. Validation of the deregulated miRNAs by q RT-PCR showed statistically significant difference in the expression levels in the breast cancers with brain metastasis compared to breast cancers without brain metastasis (Kruskal-Wallis test; p < 0.001).

Conclusions:

A unique set of miRNAs were deregulated in breast cancers with brain metastasis. This panel of altered miRNAs have clinical relevance since they can be silenced by antagomirs (chemically modified anti-miRNA oligonucleotides) to treat and prevent brain metastasis. These molecular microRNA signature-based novel targeted prophylactic and therapeutic strategies could improve patients’ quality of life and overall survival in the era of personalized and precision medicine.

Citation Information: Cancer Res 2013;73(24 Suppl): Abstract nr P4-15-07.

Erratum: Epigenetic silencing of miR-34a in human prostate cancer cells and tumor tissue specimens can be reversed by BR-DIM treatment

Androgen Receptor (AR) signaling is critically important during the development and progression of prostate cancer (PCa). The AR signaling is also important in the development of castrate resistant prostate cancer (CRPC) where AR is functional even after androgen deprivation therapy (ADT); however, little is known regarding the transcriptional and functional regulation of AR in PCa. Moreover, treatment options for primary PCa for preventing the occurrence of CRPC is limited; therefore, novel strategy for direct inactivation of AR is urgently needed. In this study, we found loss of miR-34a, which targets AR, in PCa tissue specimens, especially in patients with higher Gleason grade tumors, consistent with increased expression of AR. Forced over-expression of miR-34a in PCa cell lines led to decreased expression of AR and prostate specific antigen (PSA) as well as the expression of Notch-1, another important target of miR-34a. Most importantly, BR-DIM intervention in PCa patients prior to radical prostatectomy showed reexpression of miR-34a, which was consistent with decreased expression of AR, PSA and Notch-1 in PCa tissue specimens. Moreover, BR-DIM intervention led to nuclear exclusion both in PCa cell lines and in tumor tissues. PCa cells treated with BR-DIM and 5-aza-dC resulted in the demethylation of miR-34a promoter concomitant with inhibition of AR and PSA expression in LNCaP and C4-2B cells. These results suggest, for the first time, epigenetic silencing of miR-34a in PCa, which could be reversed by BR-DIM treatment and, thus BR-DIM could be useful for the inactivation of AR in the treatment of PCa.[This corrects the article on p. 14 in vol. 4.].

In-patient discharge rates for the irritable bowel syndrome - an analysis of national trends in the United States from 1997 to 2010

BACKGROUND

Irritable bowel syndrome (IBS) is one of the most common out-patient diagnoses in primary care and gastroenterology. There are limited data on the rate and costs associated with in-patient discharges for IBS.

AIM

To estimate the incidence and costs of hospital discharges for IBS in the United States.

METHODS

We analysed the National Inpatient Sample database for all subjects in which IBS (ICD-9 code: 564.1) was the principal discharge diagnosis from 1997 to 2010. The National Inpatient Sample contains data from approximately 8 million hospital stays each year. Our findings reflected patient and hospital characteristics like geographical region and bed size.

RESULTS

In 1997, there were 11 433 patients with a principal discharge diagnosis of IBS as compared to 12 842 in 2010 (P > 0.9, GoF test). The mean length of stay for IBS also remained the same between 1997 and 2010 at 3.7 ± 0.1 days. However, during this period, the mean hospital charges per hospitalization increased by 207.8% from $6873 ± 198 in 1997 to $21 153 ± 598 in 2010 (P < 0.01). The aggregate charges (i.e., 'national bill') for IBS increased by 245.5% from $78 524 129 ± 3 781 316 in 1997 to $271 311 405 ± 14 023 289 in 2010 (P < 0.01).

CONCLUSIONS

The number of in-patient discharges and length of stay for IBS have remained relatively stable between 1997 and 2010, whereas the cost associated with these discharges has increased significantly. In-patient costs associated with IBS contribute significantly to the total healthcare bill. Further research on the cost-effectiveness of diagnostic procedures and therapies in IBS is required.

A chronological expression profile of gene activity during embryonic mouse brain development

The brain is a functionally complex organ, the patterning and development of which are key to adult health. To help elucidate the genetic networks underlying mammalian brain patterning, we conducted detailed transcriptional profiling during embryonic development of the mouse brain. A total of 2,400 genes were identified as showing differential expression between three developmental stages. Analysis of the data identified nine gene clusters to demonstrate analogous expression profiles. A significant group of novel genes of as yet undiscovered biological function were detected as being potentially relevant to brain development and function, in addition to genes that have previously identified roles in the brain. Furthermore, analysis for genes that display asymmetric expression between the left and right brain hemispheres during development revealed 35 genes as putatively asymmetric from a combined data set. Our data constitute a valuable new resource for neuroscience and neurodevelopment, exposing possible functional associations between genes, including novel loci, and encouraging their further investigation in human neurological and behavioural disorders.

Basics of kidney biopsy: A nephrologist's perspective

The introduction of the kidney biopsy is one of the major events in the history of nephrology. Primary indications of kidney biopsy are glomerular hematuria/proteinuria with or without renal dysfunction and unexplained renal failure. Kidney biopsy is usually performed in prone position but in certain situations, supine and lateral positions may be required. Biopsy needles have changed with times from Vim–Silverman needle to Tru-cut needle to spring-loaded automatic gun. The procedure has also changed from blind bedside kidney biopsy to ultrasound marking to real-time ultrasound guidance to rarely computerized tomography guidance and laparoscopic and open biopsy. In very specific situations, transjugular kidney biopsy may be required. Most of the centers do kidney biopsy on short 1-day admission, whereas some take it as an outdoor procedure. For critical interpretation of kidney biopsy, adequate sample and clinical information are mandatory. Tissue needs to be stained with multiple stains for delineation of various components of kidney tissue. Many consider that electron microscopy (EM) is a must for all kidney biopsies, but facilities for EM are limited even in big centers. Sophisticated tests such as immunohistochemistry and in-situ hybridization are useful adjuncts for definitive diagnosis in certain situations.

Molecular characterisation of drug resistance in Mycobacterium tuberculosis isolates from North India

SETTING

A tertiary care hospital in North India.

OBJECTIVES

To analyse the frequency of mutations associated with resistance to rifampicin (RMP), isoniazid (INH) and streptomycin (SM) in Mycobacterium tuberculosis.

DESIGN

M. tuberculosis isolates from 171 pulmonary tuberculosis (TB) patients (newly diagnosed 102, 59.6%; retreated 69, 40.3%) were analysed. Drug susceptibility testing was performed using the proportion method and resistant isolates were characterised using the polymerase chain reaction, followed by restriction fragment length polymorphism and/or DNA sequencing, to screen for mutations in rpoB, katG, mabA-inhA and rpsL.

RESULTS

Of the 171 isolates, 16.9% (29/171) were multidrug-resistant. Of the 102 newly diagnosed and 69 retreated cases, respectively 5.9% (6/102) and 33.3% (23/69) were multidrug-resistant. rpoB mutations were found in 100% (31/31) of the RMP-resistant isolates, the most common being S531L in 74.2% (23/31); katG315 mutations were found in 79.6% (35/44) of the INH-resistant isolates; however, no mabA-inhA (-15) mutation was found; rpsL mutations were found in 48.9% (24/49) of the SM-resistant isolates, and codon 43 mutation were found in 42.5% (21/49).

CONCLUSIONS

This study characterises drug resistance-associated mutations in M. tuberculosis, information that could be used for the rapid screening of drug-resistant TB.

Post LASIK progressive astigmatism in a child with partially accommodative esotropia

INTRODUCTION

Refractive surgery is considered a safe and effective method for correction of refractive errors in adults.

OBJECTIVE

To report an unusual case of a young child with partially accommodative esotropia presenting with deterioration of vision and worsening of esotropia following refractive surgery.

CASE REPORT

Unanticipated and progressive irregular corneal astigmatism along with deterioration of visual acuity and loss of stereopsis developed post- LASIK in a seven-year-old Indian child with partially accommodative esotropia.

CONCLUSION

Keratorefractive surgery in young children has to be undertaken with caution, especially in such cases where there is no medical indication for refractive surgery and waiting beyond teenage years is a viable option.

MicroRNA profiling of diagnostic needle aspirates from patients with pancreatic cancer

Background:

A major challenge to the development of biomarkers for pancreatic cancer (PC) is the small amount of tissue obtained at the time of diagnosis. Single-gene analyses may not reliably predict biology of PC because of its complex molecular makeup. MicroRNA (miRNA) profiling may provide a more informative molecular interrogation of tumours. The primary objective of this study was to determine the feasibility of performing miRNA arrays and quantitative real-time PCR (qRT–PCR) from archival formalin-fixed paraffin-embedded (FFPE) cell blocks obtained from fine-needle aspirates (FNAs) that is the commonest diagnostic procedure for suspected PC.

Methods:

MicroRNA expression profiling was performed on FFPE from FNA of suspicious pancreatic masses. Subjects included those who had a pathological diagnosis of pancreatic adenocarcinoma and others with a non-malignant pancreatic histology. Exiqon assay was used to quantify miRNA levels and qRT–PCR was used to validate abnormal expression of selected miRNAs.

Results:

A total of 29 and 15 subjects had pancreatic adenocarcinoma and no evidence of cancer, respectively. The RNA yields per patient varied from 25 to 100 ng. Profiling demonstrated deregulation of over 228 miRNAs in pancreatic adenocarcinoma of which the top 7 were further validated by qRT–PCR. The expression of let-7c, let-7 f, and miR-200c were significantly reduced in most patients whereas the expression of miR-486-5p and miR-451 were significantly elevated in all pancreas cancer patients. MicroRNAs let-7d and miR-423-5p was either downregulated or upregulated with a significant inter-individual variation in their expression.

Conclusion:

This study demonstrated the feasibility of using archival FFPE cell blocks from FNAs to establish RNA-based molecular signatures unique to pancreatic adenocarcinoma with potential applications in clinical trials for risk stratification, patient selection, and target validation.

Rapid detection of rifampicin, isoniazid and streptomycin resistance in Mycobacterium tuberculosis clinical isolates by high-resolution melting curve analysis

AIMS

This study was carried out to evaluate high-resolution melting (HRM) curve analysis assay for detection of mutations in three drug resistance-associated genes of Mycobacterium tuberculosis.

METHODS AND RESULTS

Clinical isolates of Myco. tuberculosis phenotypically resistant to rifampicin (n = 29), isoniazid (n = 35) and streptomycin (n = 34) were analysed for mutations in rpoB, katG and rpsL genes, respectively, by HRM curve analysis and DNA sequencing. HRM curve assay resulted in 11 clearly distinguishable melt curves denoting eight types of mutations responsible for drug resistance. For the three drugs, respectively, the sensitivity of HRM curve assay was found to be 93·1, 80 and 61·8% compared to the phenotypic resistance patterns, and 93·1, 93·3 and 100% in comparison with the DNA sequencing.

CONCLUSIONS

The sensitivity and specificity of HRM curve assay was found to be comparable to DNA sequencing. The assay offers the advantage of high throughput, single step, rapid work flow and cost effectiveness and can be utilized as a rapid screening method for detection of drug-resistant tuberculosis.

SIGNIFICANCE AND IMPACT OF THE STUDY

HRM curve assay may prove to be an important tool for the development of rapid molecular diagnostic assays for detection of mutation-based drug resistance.

Accommodative spasm with bilateral vision loss due to untreated intermittent exotropia in an adult

Background: Intermittent exotropia (IXT) is an exodeviation intermittently controlled by fusional mechanisms. Patients with IXT may present with asthenopic symptoms, blurred vision, headaches, diplopia or visual confusion and reading difficulties; especially after prolonged periods of near work. Objective: To report the presentation and management of a young adult with intractable accommodative spasm secondary to long standing intermittent exotropia. Case: The patient was found to have bilateral accommodative spasm with high pseudomyopia and severe impairment of vision. There was a tendency for recurrence with discontinuation of cycloplegics.Conclusion: A total relief of symptoms was noticed after strabismus surgery was undertaken for the exotropia. A detailed orthoptic evaluation with emphasis on recognizing accommodative spasm as an unusual presentation of IXT, could aid in appropriate diagnosis and treatment of such cases.DOI: http://dx.doi.org/10.3126/nepjoph.v4i2.6552 Nepal J Ophthalmol 2012; 4 (2): 319-322

The pathology and clinical features of early recurrent membranous glomerulonephritis

We assessed the earliest manifestations of recurrent membranous glomerulonephritis (MGN) in renal allografts. Clinical, laboratory and pathologic data were reviewed in 21 patients at the initial biopsy within 4 months post-transplant with evidence of MGN and on follow-up biopsies, compared to a biopsy control group of eight transplants without recurrent MGN. The mean time of first biopsy with pathologic changes was 2.7 months. In each earliest biopsy, immunofluorescence (IF) showed granular glomerular basement membrane (GBM) staining for C4d, IgG, kappa and lambda. IF for C3 was negative or showed trace staining in 16/21. On each MGN biopsy positive by IF, 14/19 showed absence of deposits or rare tiny subepithelial deposits by electron microscopy (EM). At the earliest biopsy, the mean proteinuria was 1.1 g/day; 16 patients had <1 g/day proteinuria. Follow-up was available in all patients (mean 35 months posttransplant). A total of 13 patients developed >1 g/day proteinuria; 12 were treated with: rituximab (n = 8), ACEI and increased prednisone dose (n = 2), ACEI or ARB only (n = 2). All patients showed reduction in proteinuria after treatment. A total of 11/16 patients showed progression of disease by EM on follow-up biopsy. Recognition of early allograft biopsy features aids in diagnosis of recurrent MGN before patients develop significant proteinuria.

Retinoblastoma

Retinoblastoma is the most common intraocular malignancy in children and one of the very few life-threatening ophthalmic conditions. Genetically, the disease may be heritable or non-heritable. It can have unilateral or bilateral involvement and can present either sporadically or with a positive family history. Leukocoria and strabismus are the most common presentations. Diagnosis is made by indirect ophthalmoscopy aided by imaging techniques. Multidisciplinary management is aimed at saving lives, salvaging the globe and maintaining good vision. The use of neoadjuvant chemotherapy and focal treatments, such as cryotherapy, laser photocoagulation, transpupillary thermotherapy, brachytherapy and periocular chemotherapy, form the mainstay of globe preserving treatment in retinoblastoma. In developing countries, retinoblastoma is unfortunately accompanied by a high mortality rate due to delayed diagnosis made at advanced stages of the disease. Early diagnosis and timely management are vital for a good prognosis.