Comparative Analysis of Oct4 in Different Histological Subtypes of Esophageal Squamous Cell Carcinomas in Different Clinical Conditions

Background: Esophageal squamous cell carcinoma (ESCC) is a common cancer with poor prognosis. It hasbeen hypothesized that Oct4 positive radioresistant stem cells may be responsible for tumor recurrence. Hence,we evaluated Oct4 expression in ESCC in pre-treatment, post neo-adjuvant residual and post-surgical recurrenttumours. Materials and
Methods: Endoscopic mucosal biopsies were used to study Oct4 expression and theobservations were correlated with histological tumor grades, patient data and clinical background.
Results: Allpatients presented with dysphagia with male predominance and a wide age range. Majority of the patients hadintake of mixed diet, history of alcohol and tobacco intake was documented in less than half of the patients. Oct4 expression was significantly higher in poorly differentiated (PDSCC) and basaloid (BSCC) subtypes than theother better differentiated tumor morphology. Oct4 was also expressed by adjoining esophageal mucosa showinglow grade dysplasia and basal cell hyperplasia (BCH). Biopsies in PDSCC and BSCC groups were more likelyto show a positive band for Oct4 by polymerase chain reaction (PCR). Dysplasia and BCH mucosa also showedOct4 positivity by PCR. All mucosal biopsies with normal morphology were negative for Oct4. Number of tissuesamples showing Oct4 positivity by PCR was higher than that by the conventional immunohistochemistry (p>0.05).Oct4 expression pattern correlated only with tumor grading, not with other parameters including the clinicalbackground or patient data.
Conclusions: Our observations highlighted a possible role of Oct4 in identifyingputative cancer stem cells in ESCC pathobiology and response to treatment. The implications are either in vivoexistence of Oct4 positive putative cancer stem cells in ESCC or acquisition of cancer stem cell properties bytumor cells as a response to treatment given, resulting ultimately an uncontrolled cell proliferation and treatmentfailure.