Dipok Kumar Dhar

Prognostic Impact of Hypoxia-Inducible Factors 1α and 2α in Colorectal Cancer Patients: Correlation with Tumor Angiogenesis and Cyclooxygenase-2 Expression

Purpose: Angiogenesis plays an important role in a multitude of biological processes including those of tumorigenesis and cancer progression. Hypoxia is the prime driving factor for tumor angiogenesis and the family of hypoxia-inducible factors (HIFs) plays a pivotal role in this process. The role of HIF in tumor angiogenesis has been underscored in different carcinomas but yet to be reported for colorectal carcinomas. Experimental Design: In this study, we examined HIF [HIF-1α (HIF1) and HIF-2α (HIF2)] expression in 87 curatively resected colorectal carcinoma samples, and the results were correlated with clinicopathological factors, microvessel density, cyclooxygenase 2 expression, and patient prognosis. Results: HIF1 (44.8%) was more frequently expressed than HIF2 (29.9%). Most of the clinicopathological factors representing the tumor aggressiveness were significantly correlated with overexpression of HIF2 but not with HIF1 expression. HIF2 expression had direct correlation with microvessel density and cyclooxygenase 2 expression. and, in contrast, HIF1 expression had a weak but significant inverse correlation in T1 and T2 tumors only. HIF2 expression alone and the combined expression of HIF1 and HIF2 had significant impact on patient survival. In the multivariate analysis, however, only the combined expression of HIF1 and HIF2 remained independently significant. Conclusions: Taken together, our results suggest that HIF2 expression may play an important role in angiogenesis and that the combined expression of HIF1 and HIF2 may play an important role in tumor progression and prognosis of colorectal carcinomas. Therefore, HIF expression could be a useful target for therapeutic intervention.

Downregulation of KiSS‐1 expression is responsible for tumor invasion and worse prognosis in gastric carcinoma

KiSS‐1 is a promising candidate tumor‐suppressor gene and may play a key role in the metastatic cascade. The expression profile and the role of KiSS‐1 in cancer progression are largely unknown in most of the cancers, including gastric cancer. In this study, KiSS‐1 expression was evaluated by RNase protection assay and localization was done by in situ hybridization in 40 gastric cancers and their adjacent normal gastric mucosa. For comparison with clinicopathologic characteristics and patient prognosis, all patients were divided into 2 groups having high and low KiSS‐1 expression by using the median as the cutoff value of KiSS‐1 expression as determined by the RNase protection assay. Gastric cancers with low KiSS‐1 had frequent venous invasion, distant metastasis and tumor recurrence. Accordingly, patients with low KiSS‐1‐expressing tumors had a significantly worse overall and disease‐free survival. In multivariate analysis, KiSS‐1 became the strongest independent prognostic factor among the conventional prognosticators for gastric cancer patients. Collectively, these findings suggest that KiSS‐1 may play a crucial role in gastric cancer invasion and could be a useful target for therapeutic intervention.

Body Mass Index Determines the Success of Lymph Node Dissection and Predicts the Outcome of Gastric Carcinoma Patients

We tried to determine the role of the body mass index (BMI) on the extent of lymph node dissection in gastric cancer surgery. Seven hundred and eighty-seven patients with gastric carcinoma were reviewed. Ninety-two (11%) patients exceeded the upper limit of the optimum BMI. Significantly fewer lymph nodes were removed following D2 (p = 0.002) and ≥D3 (p = 0.023) dissections, and the lymph node ratio was significantly (p = 0.0383) higher in overweight patients. The recurrence-free survival was significantly (p = 0.0297) shorter in T2/T3 cases with high BMI, and BMI (relative risk 1.85) became an independent prognostic factor in multivariate analysis. Higher BMI hampers regional lymph node dissection in gastric cancer patients and became an independent predictor of disease recurrences in T2/T3 gastric cancers.

Sinusoidal endothelial cell proliferation and expression of angiopoietin/Tie family in regenerating rat liver

BACKGROUND/AIMS Angiogenesis is essential in liver regeneration. However, only little is known about sinusoidal endothelial cell proliferation and the role of different angiogenic growth factors and their receptors during regeneration. METHODS Seventy percent hepatectomy was carried out on male rats. Serial changes in endothelial cell proliferation were evaluated by immunohistochemistry. The mRNA expressions of angiogenic growth factors (vascular endothelial growth factor (VEGF) and angiopoietins 1 and 2) and their receptors (flt-1, flk-1, Tie-1 and Tie-2) in the whole liver were evaluated by semi-quantitative RT-PCR. RESULTS Significant elevation of endothelial cell proliferation started at 48 h and peaked at 72 h after hepatectomy. The ratio of sinusoids to liver tissue area initially decreased at 72 h, and thereafter, significantly increased at 96 h. VEGF related factors had early peaks, which coincided with the endothelial proliferation. flt-1, flk-1 and VEGF expressions peaked at 24, 48 and 72 h, respectively. angiopoietin/Tie factors peaked at 96 h, except Ang-2, which gradually increased and peaked at 168 h. CONCLUSIONS During liver regeneration, hepatocyte proliferation was followed by endothelial cell proliferation. The VEGF family and angiopoietin/Tie system may have distinct roles in angiogenesis, with an enhanced expression of the VEGF family in the early phase of regeneration followed by angiopoietin/Tie expression.

Expression and prognostic significance of PTEN product protein in patients with esophageal squamous cell carcinoma

PTEN is a candidate tumor‐suppressor gene in a variety of malignant tumors. The prognostic importance of PTEN product protein (PTEN) and its correlation with clinicopathologic characteristics have yet to be delineated in patients with esophageal carcinoma.

The prognostic significance of microvessel density and thymidine phosphorylase expression in squamous cell carcinoma of the esophagus.

Squamous cell carcinoma (SCC) of the esophagus is among the most malignant of neoplasms and is associated with a dismal prognosis. Although tumor microvessel density (MVD) is an important prognostic factor in several carcinomas, its role in SCC of the esophagus is still controversial. Also, the role of thymidine phosphorylase (dThdPase), a key angiogenic growth factor, is yet to be delineated in this disease.

Esophageal Resection in Elderly Esophageal Carcinoma Patients: Improvement in Postoperative Complications

BACKGROUND Advanced age is considered to be a relative contraindication for radical esophagectomy with a three-field lymph node dissection. METHODS Preoperative risks, postoperative morbidity and mortality, and long-term survival in 55 elderly patients (> or =70 years) who had undergone extensive esophagectomy for esophageal carcinoma were compared with those of 149 younger patients (<70 years). RESULTS Elderly patients had worse preoperative cardiopulmonary function and had more frequent postoperative cardiopulmonary complications compared with younger patients (p < 0.05). The postoperative death rate was not statistically different between the elderly (10.9%) and younger groups (5.4%). When the study period was divided into an early and a late phase, the postoperative death rate dropped significantly (p < 0.05) in recent years (1.4%) when compared with the previous era (10.0%). The overall survival rates were not different between elderly and younger patients. CONCLUSIONS Preoperative cardiopulmonary risk factors and postoperative complications after esophagectomy were more frequently noticed in elderly patients than in younger patients. A dramatic improvement in postoperative death was noticed in recent years. The long-term survival of elderly patients after extended esophagectomy was almost similar to that in younger patients.

Tetracycline analogues (doxycycline and COL-3) induce caspase-dependent and -independent apoptosis in human colon cancer cells

Tetracycline analogues (TCNAs) possess cytotoxic activities as well as matrix metalloproteinase (MMP) inhibitory properties. Previously, we demonstrated that doxycycline (DOXY) could induce apoptosis in human HT29 colon cancer cells. In present study, the molecular apoptotic mechanisms induced by two kinds of TCNAs, designated as DOXY and COL‐3 (chemically modified tetracycline‐3; 6‐demethyl, 6‐deoxy, 4‐dedimethylamino tetracycline), were evaluated in cultured HT29 cells. Both TCNAs inhibited the proliferation of 6 different colorectal cancer cell lines in a dose‐dependent manner. Especially, COL‐3 had a stronger effect on cancer cells than DOXY. Apoptotic changes were actually observed by 10 μg/ml COL‐3 and 20 μg/ml DOXY in a time‐dependent manner. COL‐3 produced the increase in cytosolic cytochrome c and the loss of mitochondrial membrane potential after 3 hr treatment, and thereafter activated caspases. In case of DOXY, these changes were observed after 24 hr. Bax translocation was not a prerequisite for cytochrome c releasing in COL‐3 treatment. Pretreated pancaspase inhibitor (Z‐VAD‐FMK) reduced COL‐3 and DOXY mediated apoptosis up to 81.3 and 35.3%, as compared with nontreated cells, respectively. These data indicated that TCNAs could induce mitochondria‐mediated apoptosis through both caspase‐dependent and ‐independent pathway. In fact, endonuclease G and apoptosis‐inducing factor were released into cytosol after the treatment of TCNAs, which indicated that caspase‐independent apoptotic pathway is also one of the key mechanisms for the treatment of TCNAs. Taken together, we believe that TCNAs could have strong potentials for clinical application in treating colorectal cancers and improve cancer chemotherapy.

Antiangiogenic therapy of human esophageal cancers with thalidomide in nude mice

BACKGROUND Thalidomide (alpha-N-phthalimidoglutarimide) is attracting new attention because of its antiangiogenic effect in corneal neovascularization models. However, the effect of this agent on esophageal carcinoma is yet to be established. METHODS The human esophageal squamous cell carcinoma strains ES63 and ES80 implanted subcutaneously in nude mice were used to evaluate the antiangiogenic effect of thalidomide (200 mg/kg/d) after daily gavage or intraperitoneal administration. Tumor size was measured, and assessment of microvessel density was performed histochemically with Griffonia simplicifolia lectin I. Characterizations of angiogenic growth factors, vascular endothelial growth factor, basic fibroblast growth factor, and thymidine phosphorylase in ES63 and ES80 tumors were done by immunohistochemical staining and reverse transcription-polymerase chain reaction. RESULTS ES63 strongly expressed 3 angiogenic factors, but ES80 showed moderate expression of thymidine phosphorylase and only weak or no expression of vascular endothelial grown factor and basic fibroblast growth factor at protein and messenger RNA levels. In ES63 intraperitoneal injection of thalidomide produced significant (P < .05) inhibition of tumor growth, but there was no effect after gastric gavage. Also, a significantly (P < .0005) lower microvessel density was encountered in the intraperitoneal thalidomide group. However, in the ES80 tumor strain thalidomide had no antiangiogenic effect after either intraperitoneal or oral administration. CONCLUSIONS These data indicate that thalidomide exerts an antiangiogenic effect on solid tumor after intraperitoneal administration. Thalidomide might be one of the hopeful antiangiogenic drugs for solid tumors.

Beneficial effects of FK409, a novel nitric oxide donor, on reperfusion injury of rat liver

BACKGROUND Nitric oxide (NO) seems to play an important role in modulating tissue injury during reperfusion of the liver. In this study, we have evaluated and compared the effects of FK409 (FK), a potent spontaneous NO releaser, and L-arginine in ischemia-reperfusion injury of the rat liver. METHODS Male Sprague-Dawley rats underwent 90 min of hepatic ischemia followed by reperfusion. FK or L-arginine was used (intravenously) in two different doses for each drug (group I, 3.2 mg/kg FK; group II, 1.6 mg/kg FK; group IV, 100 mg/kg L-arginine; and group V, 300 mg/kg L-arginine). Saline was used in control animals (group III). Hepatic enzyme status, microcirculation, serum nitrite (NO2-) and nitrate (NO3-) and tissue injury score were evaluated at predetermined times. RESULTS Serum NO2-/NO3- was elevated immediately by FK treatment dose-dependently but not by L-arginine. However, L-arginine caused late (6-24 hr) elevation of the NO metabolites dose-dependently. The elevation of serum aspartate aminotransferase and alanine aminotransferase was suppressed and hepatic microcirculation was improved in the FK-treated groups dose-dependently. L-Arginine also improved the microcirculation, but hepatic enzymes at 24 hr of reperfusion were significantly higher in group V than in the control group. These findings were well reflected by the extent of tissue injury in respective groups. CONCLUSION FK treatment in the immediate reperfusion period improves hepatic microcirculation and confers a significant protective effect on hepatic ischemia-reperfusion injury in the rat.