Ovarian Cancer: Molecular Classification and Targeted Therapy

Ovarian cancer is the deadliest gynecological cancer among women with an overall 5-year survival rate below 50% due to its asymptomatic nature, diagnosis at advanced stages, and a high recurrence rate after standard therapy in 70% of cases. Ovarian cancers are heterogenous cancers where each subtype possesses a varied morphology and biologic behavior. Accumulating evidence has identified each of these subtypes characterized with specific pathways activated in each along with specific gene alterations. For example, high-grade serous ovarian cancer is characterized by universal TP53 mutation, mucinous ovarian cancer with KRAS mutation and clear cell or endometrioid ovarian cancers with ARID1A mutations. With the current focus of molecular-targeted therapies for cancer, such druggable markers serve as excellent targets for precision therapy and combination therapy. This chapter, provides an overview of the critical molecular pathways activated in the ovarian cancer subtypes with its druggable targets studied in ovarian cancer. We also highlight the implications of miRNAs in chemoresistance and sensitivity in the regulation of ovarian cancer

DNA Damage Repair Genes and Noncoding RNA in High-Grade Gliomas and Its Clinical Relevance

Gliomas are the most common malignant tumors originating from the glial cells in the central nervous system. Grades III and IV, considered high-grade gliomas occur at a lower incidence (1.5%) but have higher mortality. Several genomic alterations like IDH mutation, MGMT mutation, 1p19q Codeletion, and p53 mutations have been attributed to its pathogenicity. Recently, several noncoding RNAs have also been identified to alter the expression of crucial genes. Current chemotherapeutic drugs include temozolomide targeting hypermethylated MGMT, a DNA repair protein; or bevacizumab, which targets VEGF. This book chapter delves deeper into the DNA damage repair pathway including its correlation with survival and the regulation of these genes by noncoding RNAs. Novel therapeutic drugs being developed are also highlighted

Plant-derived tetranortriterpenoid, methyl angolensate activates apoptosis and prevents ehrlich ascites carcinoma induced tumorigenesis in mice

Background: Cancer is a leading health problem throughout the world. For decades, natural plant products have been playing promising roles as anticancer agents. Objective: The present study aims to investigate the chemotherapeutic potential of Methyl Angolensate (MA), purified from Soymida febrifuga in mice bearing carcinoma and examines the molecular basis for its anticancer actions. Study Design: The inhibitory effects of MA treatment on the survival of mice bearing Carcinoma and adverse side effects of MA treatment in mice were analyzed. Methods: Tumor volume, life span, histopathology, Immunohistochemical (IHC) analysis, estimation of liver enzyme, alkaline phosphatase and metabolites, creatinine and urea. Results: Oral administration of MA in mice with Ehrlich Ascites Carcinoma showed significant inhibition of tumor growth compared to untreated mice. We observed a significant increase in the life span (∼4-fold) of tumor bearing animals following treatment with MA. MA affected tumor cell proliferation by activating intrinsic pathway of apoptosis without imparting any side effect on normal cells. MA treatment in mice showed no major side effects. Conclusion: MA treatment showed significant inhibition of tumor growth by inducing apoptosis as well increased life span of mice, with no adverse side effects to normal cells. Altogether, the present in vivo study provides new insights of MA serving as a cancer chemotherapeutic agent

Multi-omics analysis of the Indian ovarian cancer cohort revealed histotype-specific mutation and gene expression patterns

Introduction: In India, OVCa is women’s third most common and lethal cancer type, accounting for 6.7% of observed cancer incidences. The contribution of somatic mutations, aberrant expression of gene and splice forms in determining the cell fate, gene networks, tumour-specific variants, and the role of immune fraction infiltration have been proven essential in understanding tumorigenesis. However, their interplay in OVCa in a histotype-specific manner remains unclear in the Indian context. In the present study, we aimed to unravel the Indian population histotype-specific exome variants, differentially expressed gene modules, splice events and immune profiles of OVCa samples.Methods: We analysed 10 tumour samples across 4 ovarian cancer histotypes along with 2 normal patient samples. This included BCFtool utilities and CNVkit for exome, WGCNA and DESeq2 for obtaining differential module hub genes and dysregulated miRNA targets, CIBERSORTx for individual immune profiles and rMATS for tumour specific splice variants.Result: We identified population-specific novel mutations in Cancer Gene Census Tier1 and Tier2 genes. MUC16, MUC4, CIITA, and NCOR2 were among the most mutated genes, along with TP53. Transcriptome analysis showed significant overexpression of mutated genes MUC16, MUC4, and CIITA, whereas NCOR2 was downregulated. WGCNA revealed histotype-specific gene hubs and networks. Among the significant pathways, alteration in the immune system was one of the pathways, and immune profiling using CIBERSORTx revealed histotype-specific immune cell fraction. miRNA analysis revealed miR-200 family, miR-200a and miR-429 were upregulated in HGSOCs.Splice factor abrasion caused splicing perturbations, with the most abundant alternative splice event being exon skipping and the most spliced gene, SNHG17. Pathway analysis of spliced genes revealed translational elongation and Base excision repair as the pathways altered in OVCa.Conclusion: Integrated exome, transcriptome, and splicing patterns revealed different population-specific molecular signatures of ovarian cancer histotypes in the Indian Cohort

Formation of a G-quadruplex at the BCL2 major breakpoint region of the t(14;18) translocation in follicular lymphoma

The t(14;18) translocation in follicular lymphoma is one of the most common chromosomal translocations. Most breaks on chromosome 18 are located at the 3′-UTR of the BCL2 gene and are mainly clustered in the major breakpoint region (MBR). Recently, we found that the BCL2 MBR has a non-B DNA character in genomic DNA. Here, we show that single-stranded DNA modeled from the template strand of the BCL2 MBR, forms secondary structures that migrate faster on native PAGE in the presence of potassium, due to the formation of intramolecular G-quadruplexes. Circular dichroism shows evidence for a parallel orientation for G-quadruplex structures in the template strand of the BCL2 MBR. Mutagenesis and the DMS modification assay confirm the presence of three guanine tetrads in the structure. 1H nuclear magnetic resonance studies further confirm the formation of an intramolecular G-quadruplex and a representative model has been built based on all of the experimental evidence. We also provide data consistent with the possible formation of a G-quadruplex structure at the BCL2 MBR within mammalian cells. In summary, these important features could contribute to the single-stranded character at the BCL2 MBR, thereby contributing to chromosomal fragility

Good Cop, Bad Cop: Profiling the Immune Landscape in Multiple Myeloma

Multiple myeloma (MM) is a dyscrasia of plasma cells (PCs) characterized by abnormal immunoglobulin (Ig) production. The disease remains incurable due to a multitude of mutations and structural abnormalities in MM cells, coupled with a favorable microenvironment and immune suppression that eventually contribute to the development of drug resistance. The bone marrow microenvironment (BMME) is composed of a cellular component comprising stromal cells, endothelial cells, osteoclasts, osteoblasts, and immune cells, and a non-cellular component made of the extracellular matrix (ECM) and the liquid milieu, which contains cytokines, growth factors, and chemokines. The bone marrow stromal cells (BMSCs) are involved in the adhesion of MM cells, promote the growth, proliferation, invasion, and drug resistance of MM cells, and are also crucial in angiogenesis and the formation of lytic bone lesions. Classical immunophenotyping in combination with advanced immune profiling using single-cell sequencing technologies has enabled immune cell-specific gene expression analysis in MM to further elucidate the roles of specific immune cell fractions from peripheral blood and bone marrow (BM) in myelomagenesis and progression, immune evasion and exhaustion mechanisms, and development of drug resistance and relapse. The review describes the role of BMME components in MM development and ongoing clinical trials using immunotherapeutic approaches

Evolutionary conservation of the gene Cvsox9 in the lizard, Calotes versicolor, and its expression during gonadal differentiation

We have cloned and sequenced an orthologue of the human SOX9 gene in the lizard, Calotes versicolor, which lacks heteromorphic sex chromosomes as well as temperature-dependent sex determination. PCR amplification of Calotes cDNA using human SOX9 primers yielded an 861-bp fragment which harboured the high-mobility group domain and flanking sequences and had identity greater than 85% at nucleotide and greater than 90% at amino acid level with the hitherto known homologues of Sox9, demonstrating its evolutionary conservation. CvSox9 makes an approx. 5-kb transcript which is expressed in the genital ridge and mullerian duct of all the embryos from their very inception. In the genital ridge the expression in day 40 and day 45 embryos is confined to the embryonic testis (medulla) of only 50% embryos, indicating a shift in the expression from non-gonad-specific to testis-specific. The temporal and cell-specific expression in the genital ridge suggests a vital role for CvSox9 in the determination and/or differentiation of testis

Temporal difference between testis and ovary determinations with possible involvement of testosterone and aromatase in gonadal differentiation in TSD lacking lizard, Calotes versicolor

In the garden lizard, Calotes versicolor, which lacks identifiable sex chromosomes, incubation temperature also does not have a deterministic effect on the gender. However, the embryos reared at high temperature (33–35°C) have a shorter duration of incubation as well as gonadal differentiation. In contrast, exogenous application of the male hormone testosterone to embryos at ambient temperature (28°C) results in almost all individuals with only testis. Thus the testosterone treatment reverts genic females to males and accelerates the differentiation of testis, a feature similar to the high-temperature treatment. Treatment of eggs with estradiol shows no difference from that seen in the untreated eggs. The present series of experiments was done to establish the “window” of testosterone sensitivity and to understand the interaction between sex hormones and high temperature on gonadal differentiation. The period between day 5 and 15 of embryonic development was the window period of testosterone sensitivity for sex reversal. This period coincided with the formation of the genital ridge and its differentiation into cortex and medulla. Treatment of the 33°C-reared embryos with testosterone resulted in hatchlings of both the sexes, in contrast to only males at the ambient temperature. In contrast, at the same temperature (33°C), all the dihydrotestosterone (nonaromatisable testosterone)–treated embryos hatched into males. However, those given estradiol showed no sex bias regardless of the day of application and the concentration of drug. Eggs were also treated with aromatase inhibitor, CGS 16949 A, at ambient temperature and at 33°C. All the 33°C eggs to which the drug was given on day 25 hatched into males. These results suggest that though high temperature has no direct effect on sex determination in this species, it may have a stimulatory effect on aromatase activity, leading to the conversion of the exogenously applied testosterone into estradiol and permitting ovarian differentiation in the genic females. It also follows from the present report that the pathway of testis formation in Calotes versicolor is triggered much earlier, and irreversibly, than that for the ovary

Efficiency of nonhomologous DNA end joining varies among somatic tissues, despite similarity in mechanism

Failure to repair DNA double-strand breaks (DSBs) can lead to cell death or cancer. Although nonhomologous end joining (NHEJ) has been studied extensively in mammals, little is known about it in primary tissues. Using oligomeric DNA mimicking endogenous DSBs, NHEJ in cell-free extracts of rat tissues were studied. Results show that efficiency of NHEJ is highest in lungs compared to other somatic tissues. DSBs with compatible and blunt ends joined without modifications, while noncompatible ends joined with minimal alterations in lungs and testes. Thymus exhibited elevated joining, followed by brain and spleen, which could be correlated with NHEJ gene expression. However, NHEJ efficiency was poor in terminally differentiated organs like heart, kidney and liver. Strikingly, NHEJ junctions from these tissues also showed extensive deletions and insertions. Hence, for the first time, we show that despite mode of joining being generally comparable, efficiency of NHEJ varies among primary tissues of mammals

Differential regulation of MRN (Mre11-Rad50-Nbs1) complex subunits and telomerase activity in cancer cells

Several lines of evidence suggest that cancer progression is associated with up-regulation or reactivation of telomerase and the underlying mechanism remains an active area of research. The heterotrimeric MRN complex, consisting of Mre11, Rad50 and Nbs1, which is required for the repair of double-strand breaks, plays a key role in telomere length maintenance. In this study, we show significant differences in the levels of expression of MRN complex subunits among various cancer cells and somatic cells. Notably, siRNA-mediated depletion of any of the subunits of MRN complex led to complete ablation of other subunits of the complex. Treatment of leukemia and prostate cancer cells with etoposide lead to increased expression of MRN complex subunits, with concomitant decrease in the levels of telomerase activity, compared to breast cancer cells. These studies raise the possibility of developing anti-cancer drugs targeting MRN complex subunits to sensitize a subset of cancer cells to radio- and/or chemotherapy. (C) 2010 Elsevier Inc. All rights reserved