Amritha Suresh

Cancer stem cell mediated acquired chemoresistance in head and neck cancer can be abrogated by aldehyde dehydrogenase 1 A1 inhibition

Chemoresistance leading to disease relapse is one of the major challenges to improve outcome in head and neck cancers. Cancer Stem Cells (CSCs) are increasingly being implicated in chemotherapy resistance, this study investigates the correlation between CSC behavior and acquired drug resistance in in vitro cell line models. Cell lines resistant to Cisplatin (Cal‐27 CisR, Hep‐2 CisR) and 5FU (Cal‐27 5FUR) with high Resistance Indices (RI) were generated (RI ≥ 3) by short‐term treatment of head and neck squamous cell carcinoma (HNSCC) cell lines with chemotherapeutic drugs (Cisplatin, Docetaxel, 5FU), using a dose‐incremental strategy. The cell lines (Cal‐27 DoxR, Hep‐2 DoxR, Hep‐2 5FUR) that showed low RI, nevertheless had a high cross resistance to Cisplatin/5FU (P < 0.05). Cal‐27 CisR and DoxR showed 12–14% enrichment of CD44+ cells, while CisR/5FUR showed 4–6% increase in ALDH1A1+ cells as compared to parental cells (P < 0.05). Increased expression of stem cell markers (CD44, CD133, NOTCH1, ALDH1A1, OCT4, SOX2) in these cell lines, correlated with enhanced spheroid/colony formation, migratory potential, and increased in vivo tumor burden (P < 0.05). Inhibition of ALDH1A1 in Cal‐27 CisR led to down regulation of the CSC markers, reduction in migratory, self‐renewal and tumorigenic potential (P < 0.05) accompanied by an induction of sensitivity to Cisplatin (P < 0.05). Further, ex vivo treatment of explants (n = 4) from HNSCC patients with the inhibitor (NCT‐501) in combination with Cisplatin showed a significant decrease in proliferating cells as compared to individual treatment (P = 0.001). This study hence suggests an ALDH1A1‐driven, CSC‐mediated mechanism in acquired drug resistance of HNSCC, which may have therapeutic implications.

A randomized double-blind placebo-controlled phase IIB trial of curcumin in oral leukoplakia

Oral leukoplakia is a potentially malignant lesion of the oral cavity, for which no effective treatment is available. We investigated the effectiveness of curcumin, a potent inhibitor of NF-κB/COX-2, molecules perturbed in oral carcinogenesis, to treat leukoplakia. Subjects with oral leukoplakia (n = 223) were randomized (1:1 ratio) to receive orally, either 3.6 g/day of curcumin (n = 111) or placebo (n = 112), for 6 months. The primary endpoint was clinical response obtained by bi-dimensional measurement of leukoplakia size at recruitment and 6 months. Histologic response, combined clinical and histologic response, durability and effect of long-term therapy for an additional six months in partial responders, safety and compliance were the secondary endpoints. Clinical response was observed in 75 (67.5%) subjects [95% confidence interval (CI), 58.4–75.6] in the curcumin and 62 (55.3%; 95% CI, 46.1–64.2) in placebo arm (P = 0.03). This response was durable, with 16 of the 18 (88.9%; 95% CI, 67.2–96.9) subjects with complete response in curcumin and 7 of 8 subjects (87.5%) in placebo arm, demonstrating no relapse after 6 months follow-up. Difference in histologic response between curcumin and placebo was not significant (HR, 0.88, 95% CI, 0.45–1.71; P = 0.71). Combined clinical and histologic response assessment indicated a significantly better response with curcumin (HR, 0.50; 95% CI, 0.27–0.92; P = 0.02). Continued therapy, in subjects with partial response at 6 months, did not yield additional benefit. The treatment did not raise any safety concerns. Treatment of oral leukoplakia with curcumin (3.6 g for six months), thus was well tolerated and demonstrated significant and durable clinical response for 6 months. Cancer Prev Res; 9(8); 683–91. ©2016 AACR.

Chairside molecular imaging of aberrant glycosylation in subjects with suspicious oral lesions using fluorescently labeled wheat germ agglutinin

Aberrant sialylation is accepted as a carcinogenic biomarker. In previous work, fluorescently labeled wheat germ agglutinin (WGA) distinguished between cancerous and normal oral biopsies. The purpose of this study was to investigate WGA‐fluorescein isothiocyanate (FITC) as a point‐of‐care tool for detecting oral malignant and dysplastic lesions in vivo.

Cancer stem cell and its niche in malignant progression of oral potentially malignant disorders

OBJECTIVE The purpose of this study was to determine association between cancer stem cells (CSCs) and their niche with progression of oral potentially malignant disorders. MATERIALS AND METHODS Patients with histologically confirmed oral potentially malignant disorders, stratified into high/low risk lesions based on the degree of dysplasia and oral cancer were included in this study. Immunohistochemical profiling of markers of CSCs (CD44), endothelial cells (CD31) and CSC-vascular niche cross-talk (CXCR4 and SDF1) were carried out. Statistical analysis was performed to correlate the relationship of markers with histopathology grade (ANOVA, and χ2 test, unpaired t test) using GraphPad InStat v3.06. RESULTS The study included 550 samples (349 patients) and analysis showed progressive increase in expression levels of CSC and its niche markers with increase in grade of dysplasia as compared to the normal cohort (p < 0.05). Co-expression analysis revealed that, in comparison to the normal cohort, a larger percentage of patients showed increased expression of CD31 and CD44 (CD31high/CD44high; p < 0.05) and of CXCR4 and SDF1 (CXCR4high/SDF1high; p = 0.04), suggesting an association of the CSCs and the vascular niche. Further, distribution of patients with CD44high/CXCR4high (p < 0.05) and CD31high/SDF1high (p = 0.01) was significantly increased in the high-risk group (18%), suggesting a correlation between CD44+/CXCR4+ cells, the vascular niche and progression of oral dysplastic lesions. CONCLUSION The increased expression of CSCs, the vascular niche and their cross talk markers are associated with increase in severity of dysplasia suggesting their role in the progression of oral potentially malignant disorders and may hence be used in identifying high-risk OPMD.

Biological Basis of Treatment Failure

Despite aggressive multimodality treatment, over 50 % of oral cancers develop disease recurrence. Majority of the recurrence develop at the primary site. However intensification of locoregional therapy especially with the use of postoperative adjuvant chemoradiotherapy, a higher proportion of disease failures, is seen at the distant site. Recurrent disease is often resistant to treatment and often an indicator of incurability, especially those with metastatic disease. Mechanism of disease recurrence following surgery and chemoradiotherapy is different.

Abstract 4074: Cancer stem cells in tobacco-induced carcinogenesis and subsequent effect of ATRA-based chemoprevention

Introduction Chemoprevention is potentially the most effective method to lower the prevalence of head and neck squamous cell carcinomas (HNSCC), the sixth most common type of malignancy worldwide. The chemopreventive effects of retinoids against HNSCC have been previously reported. Retinoids however; relapse following cessation of medication is a critical problem that prevents its clinical use. The objective of this study was to determine the possible mechanism of retinoid resistance by exploring cancer stem cell mediated pathways. Experimental Procedures. In vitro cell line models of normal (NOK) and dysplastic oral keratinocytes (DOK) are being exposed to tobacco to assess the process of carcinogenic progression. The progression in the DOK and HOK cell lines will be assessed by proliferation, migration and invasion assays. The expression of stem cell markers/pathways (CD44/Hyaluronan, Wnt, Notch1, ALDH1A1) during the process of progression will be evaluated using QPCR and FACS. These cell lines will then be treated with ATRA and the subsequent effects on transformation and CSC-specific pathways further evaluated. Summary To this end, immunostaining of normal oral mucosa, potentially malignant lesions (n = 93) and malignant lesions (n = 48) for the stem cell marker CD44 was performed. CD44+ cells were found at a density of 58.57/hpf in normal mucosa, 61.56/hpf in mild dysplasia, 119.44/hpf in moderate dysplasia, and 107.6/hpf in severe dysplasia. The density of CD44+ cells in WDSCC, MDSCC and PDSCC were 183.4, 105 and 160/hpf respectively, indicates CSC cells may represent a marker of malignant progression The cell lines are currently under exposure to tobacco and the transformational changes being documented. Apart from the studies on the changes specific to CSCs, high throughput secretome and proteomic studies are also being planned to evaluate the global changes effected due to tobacco as well as due to subsequent treatment with ATRA. Conclusion This study hence attempts to provide novel insight into tobacco-induced carcinogenesis and mechanism of resistance to retinoid-based chemoprevention. Note: This abstract was not presented at the meeting. Citation Format: Subin Surendran, Christina Mimikos, Amritha Suresh, Wesley L. Hicks, Mukund Seshadri, Moni A. Kuriakose. Cancer stem cells in tobacco-induced carcinogenesis and subsequent effect of ATRA-based chemoprevention. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 4074. doi:10.1158/1538-7445.AM2015-4074