Dhwanil Damania

HDAC up-regulation in early colon field carcinogenesis is involved in cell tumorigenicity through regulation of chromatin structure.

Normal cell function is dependent on the proper maintenance of chromatin structure. Regulation of chromatin structure is controlled by histone modifications that directly influence chromatin architecture and genome function. Specifically, the histone deacetylase (HDAC) family of proteins modulate chromatin compaction and are commonly dysregulated in many tumors, including colorectal cancer (CRC). However, the role of HDAC proteins in early colorectal carcinogenesis has not been previously reported. We found HDAC1, HDAC2, HDAC3, HDAC5, and HDAC7 all to be up-regulated in the field of human CRC. Furthermore, we observed that HDAC2 up-regulation is one of the earliest events in CRC carcinogenesis and observed this in human field carcinogenesis, the azoxymethane-treated rat model, and in more aggressive colon cancer cell lines. The universality of HDAC2 up-regulation suggests that HDAC2 up-regulation is a novel and important early event in CRC, which may serve as a biomarker. HDAC inhibitors (HDACIs) interfere with tumorigenic HDAC activity; however, the precise mechanisms involved in this process remain to be elucidated. We confirmed that HDAC inhibition by valproic acid (VPA) targeted the more aggressive cell line. Using nuclease digestion assays and transmission electron microscopy imaging, we observed that VPA treatment induced greater changes in chromatin structure in the more aggressive cell line. Furthermore, we used the novel imaging technique partial wave spectroscopy (PWS) to quantify nanoscale alterations in chromatin. We noted that the PWS results are consistent with the biological assays, indicating a greater effect of VPA treatment in the more aggressive cell type. Together, these results demonstrate the importance of HDAC activity in early carcinogenic events and the unique role of higher-order chromatin structure in determining cell tumorigenicity.

Optical Detection of Buccal Epithelial Nanoarchitectural Alterations in Patients Harboring Lung Cancer: Implications for Screening

We have recently developed a novel optical technology, partial wave spectroscopic (PWS) microscopy, which is exquisitely sensitive to the nanoarchitectural manifestation of the genetic/epigenetic alterations of field carcinogenesis. Our approach was to screen for lung cancer by assessing the cheek cells based on emerging genetic/epigenetic data which suggests that the buccal epithelium is altered in lung field carcinogenesis. We performed PWS analysis from microscopically normal buccal epithelial brushings from smokers with and without lung cancer (n = 135). The PWS parameter, disorder strength of cell nanoarchitecture (L(d)), was markedly (>50%) elevated in patients harboring lung cancer compared with neoplasia-free smokers. The performance characteristic was excellent with an area under the receiver operator characteristic curve of >0.80 and was equivalent for both disease stage (early versus late) and histologies (small cell versus non-small cell lung cancers). An independent data set validated the findings with only a minimal degradation of performance characteristics. Our results offer proof of concept that buccal PWS may potentially herald a minimally intrusive prescreening test that could be integral to the success of lung cancer population screening programs.

Nanocytology of rectal colonocytes to assess risk of colon cancer based on field cancerization

Developing a minimally invasive and cost-effective prescreening strategy for colon cancer is critical because of the impossibility of conducting colonoscopy on the entire at-risk population. The concept of field carcinogenesis, in which normal-appearing tissue away from a tumor has molecular and, consequently, nano-architectural abnormalities, offers one attractive approach to identify high-risk patients. In this study, we investigated whether the novel imaging technique partial wave spectroscopic (PWS) microscopy could risk-stratify patients harboring precancerous lesions of the colon, using an optically measured biomarker (L(d)) obtained from microscopically normal but nanoscopically altered cells. Rectal epithelial cells were examined from 146 patients, including 72 control patients, 14 patients with diminutive adenomas, 20 patients with nondiminutive/nonadvanced adenomas, 15 patients with advanced adenomas/high-grade dysplasia, 12 patients with genetic mutation leading to Lynch syndrome, and 13 patients with cancer. We found that the L(d) obtained from rectal colonocytes was well correlated with colon tumorigenicity in our patient cohort and in an independent validation set of 39 additional patients. Therefore, our findings suggest that PWS-measured L(d) is an accurate marker of field carcinogenesis. This approach provides a potential prescreening strategy for risk stratification before colonoscopy.

Role of Cytoskeleton in Controlling the Disorder Strength of Cellular Nanoscale Architecture

Cytoskeleton is ubiquitous throughout the cell and is involved in important cellular processes such as cellular transport, signal transduction, gene transcription, cell-division, etc. Partial wave spectroscopic microscopy is a novel optical technique that measures the statistical properties of cell nanoscale organization in terms of the disorder strength. It has been found previously that the increase in the disorder strength of cell nanoarchitecture is one of the earliest events in carcinogenesis. In this study, we investigate the cellular components responsible for the differential disorder strength between two morphologically (and hence microscopically) similar but genetically altered human colon cancer cell lines, HT29 cells and Csk shRNA-transfected HT29 cells that exhibit different degrees of neoplastic aggressiveness. To understand the role of cytoskeleton in nanoarchitectural alterations, we performed selective drug treatment on the specific cytoskeletal components of these cell types and studied the effects of cytoskeletal organization on disorder strength differences. We report that altering the cell nanoarchitecture by disrupting cytoskeletal organization leads to the attenuation of the disorder strength differences between microscopically indistinguishable HT29 and CSK constructs. We therefore demonstrate that cytoskeleton plays a role in the control of cellular nanoscale disorder.

Insights into the field carcinogenesis of ovarian cancer based on the nanocytology of endocervical and endometrial epithelial cells

Ovarian cancer ranks fifth in cancer fatalities among American women. Although curable at early stages with surgery, most women are diagnosed with symptoms of late‐stage metastatic disease. Moreover, none of the current diagnostic techniques are clinically recommended for at‐risk women as they preferentially target low‐grade tumors (which do not affect longevity) and fail to capture early signatures of more lethal serous tumors which originate in the fimbrae region of the fallopian tubes. Hence, the early detection of ovarian cancer is challenging given the current strategy. Recently, our group has developed a novel optical imaging technique, partial wave spectroscopic (PWS) microscopy, that can quantify the nanoscale macromolecular density fluctuations within biological cells via a biomarker, disorder strength (Ld). Using the concept of field carcinogenesis, we propose a method of detecting ovarian cancer by PWS assessment of endometrial and endocervical columnar cells. The study includes 26 patients (controls = 15, cancer = 11) for endometrium and 23 (controls = 13, cancer = 10) for endocervix. Our results highlight a significant increase in Ld (% fold‐increase > 50%, p‐value < 0.05) for columnar epithelial cells obtained from cancer patients compared to controls for both endocervix and endometrium. Overall, the quantification of field carcinogenic events in the endometrium and the novel observation of its extension to the cervix are unique findings in the understanding of ovarian field carcinogenesis. We further show independent validation of the presence of cervical field carcinogenesis with micro‐RNA expression data.

Nanoscale markers of esophageal field carcinogenesis: potential implications for esophageal cancer screening.

BACKGROUND AND STUDY AIMS Esophageal adenocarcinoma (EAC) has a dismal prognosis unless treated early or prevented at the precursor stage of Barretts esophagus-associated dysplasia. However, some patients with cancer or dysplastic Barretts esophagus (DBE) may not be captured by current screening and surveillance programs. Additional screening techniques are needed to determine who would benefit from endoscopic screening or surveillance. Partial wave spectroscopy (PWS) microscopy (also known as nanocytology) measures the disorder strength (Ld ), a statistic that characterizes the spatial distribution of the intracellular mass at the nanoscale level and thus provides insights into the cell nanoscale architecture beyond that which is revealed by conventional microscopy. The aim of the present study was to compare the disorder strength measured by PWS in normal squamous epithelium in the proximal esophagus to determine whether nanoscale architectural differences are detectable in the field area of EAC and Barretts esophagus. METHODS During endoscopy, proximal esophageal squamous cells were obtained by brushings and were fixed in alcohol and stained with standard hematoxylin and Cyto-Stain. The disorder strength of these sampled squamous cells was determined by PWS. RESULTS A total of 75 patient samples were analyzed, 15 of which were pathologically confirmed as EAC, 13 were DBE, and 15 were non-dysplastic Barretts esophagus; 32 of the patients, most of whom had reflux symptoms, acted as controls. The mean disorder strength per patient in cytologically normal squamous cells in the proximal esophagus of patients with EAC was 1.79-times higher than that of controls (P<0.01). Patients with DBE also had a disorder strength 1.63-times higher than controls (P<0.01). CONCLUSION Intracellular nanoarchitectural changes were found in the proximal squamous epithelium in patients harboring distal EAC and DBE using PWS. Advances in this technology and the biological phenomenon of the field effect of carcinogenesis revealed in this study may lead to a useful tool in non-invasive screening practices in DBE and EAC.

Quantification of nanoscale density fluctuations by electron microscopy: probing cellular alterations in early carcinogenesis

Most cancers are curable if they are diagnosed and treated at an early stage. Recent studies suggest that nanoarchitectural changes occur within cells during early carcinogenesis and that such changes precede microscopically evident tissue alterations. It follows that the ability to comprehensively interrogate cell nanoarchitecture (e.g., macromolecular complexes, DNA, RNA, proteins and lipid membranes) could be critical to the diagnosis of early carcinogenesis. We present a study of the nanoscale mass-density fluctuations of biological tissues by quantifying their degree of disorder at the nanoscale. Transmission electron microscopy images of human tissues are used to construct corresponding effective disordered optical lattices. The properties of nanoscale disorder are then studied by statistical analysis of the inverse participation ratio (IPR) of the spatially localized eigenfunctions of these optical lattices at the nanoscale. Our results show an increase in the disorder of human colonic epithelial cells in subjects harboring early stages of colon neoplasia. Furthermore, our findings strongly suggest that increased nanoscale disorder correlates with the degree of tumorigenicity. Therefore, the IPR technique provides a practicable tool for the detection of nanoarchitectural alterations in the earliest stages of carcinogenesis. Potential applications of the technique for early cancer screening and detection are also discussed.

Network signatures of nuclear and cytoplasmic density alterations in a model of pre and postmetastatic colorectal cancer

Abstract. Cells contributing to the pathogenesis of cancer possess cytoplasmic and nuclear structural alterations that accompany their aberrant genetic, epigenetic, and molecular perturbations. Although it is known that architectural changes in primary and metastatic tumor cells can be quantified through variations in cellular density at the nanometer and micrometer spatial scales, the interdependent relationships among nuclear and cytoplasmic density as a function of tumorigenic potential has not been thoroughly investigated. We present a combined optical approach utilizing quantitative phase microscopy and partial wave spectroscopic microscopy to perform parallel structural characterizations of cellular architecture. Using the isogenic SW480 and SW620 cell lines as a model of pre and postmetastatic transition in colorectal cancer, we demonstrate that nuclear and cytoplasmic nanoscale disorder, micron-scale dry mass content, mean dry mass density, and shape metrics of the dry mass density histogram are uniquely correlated within and across different cellular compartments for a given cell type. The correlations of these physical parameters can be interpreted as networks whose nodal importance and level of connection independence differ according to disease stage. This work demonstrates how optically derived biophysical parameters are linked within and across different cellular compartments during the architectural orchestration of the metastatic phenotype.

Quantification of nanoscale density fluctuations using electron microscopy: Light-localization properties of biological cells

We report a study of the nanoscale mass-density fluctuations of heterogeneous optical dielectric media, including nanomaterials and biological cells, by quantifying their nanoscale light-localization properties. Transmission electron microscope images of the media are used to construct corresponding effective disordered optical lattices. Light-localization properties are studied by the statistical analysis of the inverse participation ratio (IPR) of the localized eigenfunctions of these optical lattices at the nanoscale. We validated IPR analysis using nanomaterials as models of disordered systems fabricated from dielectric nanoparticles. As an example, we then applied such analysis to distinguish between cells with different degrees of aggressive malignancy.

Nano-Architectural Alterations in Mucus Layer Fecal Colonocytes in Field Carcinogenesis: Potential for Screening

Current fecal tests (occult blood, methylation, DNA mutations) target minute amounts of tumor products among a large amount of fecal material and thus have suboptimal performance. Our group has focused on exploiting field carcinogenesis as a modality to amplify the neoplastic signal. Specifically, we have shown that endoscopically normal rectal brushings have striking nano-architectural alterations which are detectable using a novel optical technique, partial wave spectroscopic microscopy (PWS). We therefore wished to translate this approach to a fecal assay. We examined mucus layer fecal colonocytes (MLFC) at preneoplastic and neoplastic time points (confirmed with rat colonoscopy) in the azoxymethane (AOM)-treated rat model and conducted PWS analysis to derive the nano-architectural parameter, disorder strength (Ld). We confirmed these results with studies in a genetic model (the Pirc rat). We showed that MLFC appeared microscopically normal, consistent with field carcinogenesis. Ld was elevated at an early time point (5 weeks post-AOM injection, effect size = 0.40, P = 0.024) and plateaued before adenoma formation (10 weeks post-AOM, effect size = 0.66, P = 0.001), with no dramatic increase once tumors developed. We replicated these data in the preneoplastic Pirc rat with an effect size in the MLFC that replicated the rectal brushings (increase vs. age-matched controls of 62% vs. 74%, respectively). We provide the first demonstration of a biophotonics approach to fecal assay. Furthermore, targeting the nano-architectural changes of field carcinogenesis rather than the detection of tumor products may provide a novel paradigm for colorectal cancer screening. Cancer Prev Res; 6(10); 1111–9. ©2013 AACR.