Angiogenesis and Lymphangiogenesis in Salivary Gland Adenoid Cystic Carcinoma and Mucoepidermoid Carcinoma.

BACKGROUND AND PURPOSE: This study aimed to investigate the immunohistochemical expression of CD31 and podoplanin in order to examine angiogenesis and lymphangiogenesis, respectively in common malignant tumors of salivary glands. MATERIALS AND METHODS: Forty formalin-fixed, paraffinated blocks (20 adenoid cystic carcinoma and 20 mucoepidermoid carcinoma blocks) were selected from the medical archives of Amir A'lam Hospital of Tehran, Iran. Sections from the blocks were stained by CD31 and D2-40 markers via immunohistochemistry. Clinical and demographic information was extracted from the patients' records. FINDINGS: There was a significant difference between tumors in terms of intratumoral microvessel density (MVD) (P< 0.001), total MVD (P< 0.001), and intratumoral lymphatic vessel density (LVD) (P= 0.011). In mucoepidermoid carcinoma, intratumoral MVD and LVD were greater than peritumoral MVD and LVD (P= 0.001 and P< 0.001, respectively). In mucoepidermoid carcinoma, there was no relationship between histological grade with MVD (total, intratumoral or peritumoral) or LVD (total, intratumoral or peritumoral) (P> 0.05). A similar finding was reported with respect to the histopathological grade of adenoid cystic carcinoma (P> 0.05). CONCLUSION: The higher level of angiogenesis and lymphangiogenesis in mucoepidermoid carcinoma, specifically at the center of tumor, compared to adenoid cystic carcinoma, may be attributed to differences in the clinical behaviors and metastasis of tumors. Moreover, considering the high LVD at the center of tumor in mucoepidermoid carcinoma and infrequency of metastasis to regional lymph nodes in adenoid cystic carcinoma, it can play a significant role in metastasis to regional lymph nodes.

Immunoexpression of GLUT-1 and angiogenic index in pleomorphic adenomas, adenoid cystic carcinomas, and mucoepidermoid carcinomas of the salivary glands.

This study aimed to evaluate and compare the immunoexpression of glucose transporter-1 (GLUT-1) and angiogenic index between pleomorphic adenomas (PAs), adenoid cystic carcinomas (ACCs), and mucoepidermoid carcinomas (MECs) of the salivary glands, and establish associations with the respective subtype/histological grade. Twenty PAs, 20 ACCs, and 10 MECs were submitted to morphological and immunohistochemical analysis. GLUT-1 expression was semi-quantitatively evaluated and angiogenic index was assessed by microvessel counts using anti-CD34 antibody. Higher GLUT-1 immunoexpression was observed in the MECs compared to PAs and ACCs (p = 0.022). Mean number of microvessels was 66.5 in MECs, 40.4 in PAs, and 21.2 in ACCs (p < 0.001). GLUT-1 expression and angiogenic index showed no significant correlation in the tumors studied. Results suggest that differences in biological behavior of the studied tumors are related to GLUT-1. Benign and malignant salivary gland tumors differ in the angiogenic index; however, angiogenesis may be independent of the tumor cell's metabolic demand.

Vascular endothelial growth factor (VEGF) expression and microvascular density in salivary gland tumours.

This study investigates whether salivary tumours with different morphology and evolution also differ in terms of neovascularization and VEGF expression and the prognostic value of the results. Surgical specimens from 45 patients - 8 pleomorphic adenomas (PA), 7 Warthin tumours (WT), 5 basal cell adenomas (BA), 6 carcinomas ex-pleomorphic adenoma (CEPA), 6 mucoepidermoid carcinomas (MEC), 5 acinic cell carcinomas (AC), 4 adenoid cystic carcinomas (ACC) and 4 adenocarcinomas not otherwise specified (ADK NOS) - were immunostained. In malignant salivary tumours, the following mean microvascular density (MVD) values were recorded (± SD = Standard Deviation): 27.61 (SD ± 2.27) in cases with CEPA, 27.08 (DS ± 7.81) in AC and 32.93 (SD ± 7.76) in ADK NOS, with lower values for MEC 24.31(SD ± 2.88) and for ACC 22.13 (SD ± 5.44). For benign tumours, an MVD of 35.71 (SD ± 2.09) was recorded in WT and lower average values in PA (MVD = 14.84; SD ± 4.86) and in BA (MVD = 23.96; SD ± 9.13). MVD did not correlate with the investigated clinicopathological parameters. The VEGF expression is significantly more important (p = 0.001) in malignant salivary tumours as compared with benign ones. The VEGF expression and the microvascularization in salivary gland tumours are important elements to be considered when formulating a diagnosis and assessing case evolutions in patients with such tumours.

Density of mast cells and microvessels in minor salivary gland tumors.

The aim of this study was to investigate the density of mast cells and microvessels in minor salivary gland tumors. Forty-one cases of minor salivary gland tumors (pleomorphic adenoma, n = 10; adenoid cystic carcinoma, n = 11; mucoepidermoid carcinoma, n = 10; and polymorphous low-grade adenocarcinoma) were investigated using immunohistochemistry for mast cell tryptase and von-Willebrand factor. Density of mast cells was higher in mucoepidermoid carcinoma; however, no differences in the number of these cells were observed between the different types of tumors (p > 0.05). The number of mast cells was higher in periparenchymal areas in all tumors, but the difference was not significant (p > 0.05). Mucoepidermoid carcinoma showed the largest number of periparenchymal mast cells, whereas pleomorphic adenomas showed the smallest number of intraparenchymal mast cells (p > 0.05). The highest microvessel density was observed in mucoepidermoid carcinomas, being this difference statistically significant when mucoepidermoid carcinoma was compared to pleomorphic adenoma (p = 0.0034) and polymorphous low-grade adenocarcinoma (p = 0.004). Microvessel density was significantly higher in adenoid cystic carcinoma when compared to pleomorphic adenoma (p = 0.0406) and polymorphous low-grade adenocarcinoma (p = 0.0123). Comparison of mast cells and microvessel densities showed no significant difference between tumors. A quantitative difference in mast cells and microvessels was observed, particularly in mucoepidermoid carcinoma, a finding supporting the aggressive behavior of malignant salivary gland tumors without myoepithelial differentiation. Further studies are needed to determine the role of mast cells in angiogenesis, as well as in the development and biological behavior of these tumors.

Expression of Ki67 and CD105 as proliferation and angiogenesis markers in salivary gland tumors.

OBJECTIVE: To investigate the association between CD105 and tumor cell proliferation in salivary gland tumors. METHODS: In this study, 59 samples of salivary tumors from Khalili Hospital archive, including 20 cases of pleomorphic adenoma (PA), 20 cases of mucoepidermoid carcinoma (MEC) and 19 cases of adenoid cystic carcinoma, as well as 10 cases of normal salivary gland tissue, were reviewed by immunohistochemistry (IHC) for CD105 and Ki67 staining. RESULTS: CD105 positive vessels were absent in normal salivary gland tissue in the vicinity of tumors (51.6% of all tumors were positive). There was a statistically significant difference in frequency of CD105 staining between PA and malignant tumors and between four groups of different lesions (p<0.000) being highest in MEC. Intratumoral microvessel density was also elevated in malignant neoplasms (2.61 ± 3.1) as compared to PA (0.46 ± 0.6). Normal salivary glands did not express Ki67. There was a statistically significant difference in frequency and percentage of Ki67 immunoreactivity in malignant neoplasms (86.5% and 10.7 ± 10.8 respectively) compared to PA (50% and 0.78 ± 0.2) and among the four groups values were highest in MEC (p<0.000). CONCLUSION: n this study, it was observed a higher rate of angiogenesis and cellular proliferation was noted in malignant tumors compared to benign tumors, but no correlation was observed between these two markers.

Ultrasonographic appearances of mucoepidermoid carcinoma of the salivary glands.

OBJECTIVE: The objective of this study was to investigate the ability of sonography for diagnosis of mucoepidermoid carcinoma (MEC) in the salivary glands. STUDY DESIGN: Sonographic images of 74 cases were analyzed retrospectively; the features evaluated included size, echogenicity, shape, internal structure, distal acoustic enhancement, and regional lymph node enlargement and vascularization, and categorized them into 3 groups based on histology (low, intermediate, and high grade). RESULTS: The lesion size of low-grade MEC was smaller than those of intermediate- and high-grade MEC. MEC lesions of the salivary glands were mostly associated with heterogeneous echotexture, indistinct margins, irregular shape, and absence of distal acoustic enhancement. They sometimes showed cystic areas, calcifications, regional lymph node enlargement, or were well vascularized on Doppler. There were no significant sonographic differences in low-, intermediate-, and high-grade MEC. CONCLUSIONS: Salivary MEC presents a variety of sonographic appearances, which would aid in the diagnosis of salivary MEC.

Angiogenesis and lymphangiogenesis in mucoepidermoid carcinoma of minor salivary glands.

BACKGROUND: Mucoepidermoid carcinoma is the most common malignant tumor of salivary glands. This tumor is characterized by a great variability in clinical behavior, and little is known about the pathological mechanisms involved in its variance. Angiogenesis is an important step in tumor progression and is believed to be an essential event for metastatic dissemination. METHODS: We aimed to investigate angiogenesis and lymphangiogenesis in mucoepidermoid carcinoma measuring the density of neoformed and lymphatic vessels using CD105 and D2-40 antibodies, respectively, and by immunohistochemical evaluation of VEGF-A and VEGF-C proteins. It was also investigated the expression of D2-40 in neoplastic cells. RESULTS: We studied 26 cases of mucoepidermoid carcinoma, which showed great angiogenic activity measured by neoformed vessel density. However, a low density of lymphatics was observed. VEGF-A, VEGF-C, and D2-40 were commonly detected in mucoepidermoid carcinoma, but only VEGF-A expression correlated with neoformed vessel density. Recurrence and nodal metastasis were associated with low VEGF-A expression and low neoformed vessel density, indicating that impaired angiogenesis could lead to an aggressive phenotype. CONCLUSIONS: Angiogenesis seems important in the modulation of mucoepidermoid carcinoma pathogenesis; however, none of the parameters analyzed could predict tumor behavior.

Role of ultrasound in the assessment of benignity and malignancy of parotid masses.

OBJECTIVES: This study aimed to investigate the value of ultrasound in the identification of benign and malignant parotid masses. METHODS: Data of 189 patients with parotid gland masses undergoing ultrasound-guided fine-needle aspiration (FNA), core biopsy or surgery were reviewed retrospectively and the presumed sonographic diagnoses were compared with the histopathology. The sensitivity, specificity and accuracy of sonographic diagnoses were assessed and the sonographic characteristics of those lesions, including shape, margin, echogenicity, echotexture and vascularization, were studied. RESULTS: Of the 189 patients, the final pathological diagnosis included 18 malignant tumours and 171 benign masses; the presumed sonographic diagnoses showed 165 cases as benign and probably benign masses (11 cases were confirmed malignant, 154 cases benign) and 24 cases were diagnosed as probably malignant and malignant masses (7 cases were confirmed malignant, 17 cases benign). The sensitivity, specificity, positive predictive value, negative predictive value and accuracy of ultrasound for the diagnosis of parotid gland masses were 38.9%, 90.1%, 29.2%, 93.3% and 85.2%, respectively, and accuracy for malignant masses was 20%. The sonographic characteristics of parotid masses between benign and malignant lesions had no significant differences. The parotid gland masses in this study included pleomorphic adenoma, Warthin's tumour, retention cyst, haemangiomas, chronic granuloma, lymphoma, fibrolipoma, abscess, basal cell adenoma, oncocytoma, lymphatic tuberculosis, myoepithelioma, neurilemmoma, mucoepidermoid carcinoma, adenoid cystic carcinoma, alveolar soft part sarcoma and retinal blastoma (metastasis). CONCLUSIONS: It is challenging to use sonography for differentiating between benign and malignant parotid gland masses. To make a definite diagnosis, ultrasound-guided FNA or core biopsy is advocated.

Extracellular matrix metalloproteinase inducer expression in salivary gland tumors: a correlation with microvessel density.

The purpose of this study was to investigate the expression pattern of extracellular matrix metalloproteinase inducer (EMMPRIN) as well as the correlation between EMMPRIN and microvessel density (MVD) in salivary gland tumors. Extracellular matrix metalloproteinase inducer expression and MVD were examined immunohistochemically on paraffin-embedded tissue specimens from 95 patients with salivary gland tumors, who underwent surgical resection from 1998 to 2006. Reverse transcription-polymerase chain reaction was used to monitor EMMPRIN mRNA expression in frozen samples. Extracellular matrix metalloproteinase inducer expression in mucoepidermoid carcinomas and adenoid cystic carcinomas was significantly higher than in normal salivary gland tissues and pleomorphic adenomas (P < 0.05). The MVD of mucoepidermoid carcinomas and adenoid cystic carcinomas was significantly higher compared with pleomorphic adenomas (P < 0.05). The MVD of the EMMPRIN-positive expression group was significantly higher than the MVD of the EMMPRIN-negative expression group (P < 0.05). Extracellular matrix metalloproteinase inducer mRNA expression in malignant salivary gland tumors was higher than that in pleomorphic adenomas (P < 0.05). This study suggests that EMMPRIN expression is an important feature of malignant salivary gland tumors and can be used as a biologic marker to characterize salivary gland tumors. Extracellular matrix metalloproteinase inducer is also a positive angiogenic factor in salivary gland tumors.

Derived vascular endothelial cells induced by mucoepidermoid carcinoma cells: 3-dimensional collagen matrix model.

Mucoepidermoid carcinoma undergoes uniquely vigorous angiogenic and neovascularization processes, possibly due to proliferation of vascular endothelial cells (ECs) induced by mucoepidermoid carcinoma cells (MCCs) in their three-dimensional (3D) microenvironment. To date, no studies have dealt with tumor cells and vascular ECs from the same origin of mucoepidermoid carcinoma using the in vitro 3D microenvironment model. In this context, the current research aims to observe neovascularization with mucoepidermoid carcinoma microvascular ECs (MCMECs) conditioned by the microenvironment in the 3D collagen matrix model. We observed the growth of MCMECs purified by immunomagnetic beads and induced by MCCs, and characteristics of tubule-like structures (TLSs) formed by induced MCMECs or non-induced MCMECs. The assessment parameters involved the growth curve, the length, the outer and inner diameters, and the wall thickness of the TLSs, and the cell cycle. Results showed that MCCs induced formation of the TLSs in the 3D collagen matrix model. A statistically significant difference was noted regarding the count of TLSs between the control group and the induction group on the 4th day of culture (t=5.00, P=0.001). The outer and inner diameters (t(1)=5.549, P(1)=0.000; t(2)=10.663, P(2)=0.000) and lengths (t=18.035, P=0.000) of the TLSs in the induction group were statistically significant larger than those in the control group. The TLSs were formed at the earlier time in the induction group compared with the control group. It is concluded that MCCs promote growth and migration of MCMECs, and formation of the TLSs. The 3D collagen matrix model with MCMECs induced by MCCs in the current research may be a favorable choice for research on pro-angiogenic factors in progression of mucoepidermoid carcinoma.

Midkine expression in malignant salivary gland tumors and its role in tumor angiogenesis.

The aims of this study were to investigate midkine (MK) expression patterns in salivary gland tumors (SGTs) and to evaluate the correlation between MK expression and the degree of malignancy. We performed immunohistochemistry to examine MK expression in specimens of adenoid cystic carcinoma (ACC), mucoepidermoid carcinoma (MEC), and pleomorphic adenoma (PA). In addition, we performed immunohistochemistry for CD31 and measured microvessel density (MVD), which is an indicator of angiogenesis. Immunohistochemistry showed that MK protein expression was significantly higher in specimens of malignant SGTs (ACC [P<0.01] and MEC [P<0.001]) than in benign SGT (PA) samples. Furthermore, MVD values tended to be higher in cases that exhibited high expression of MK, which indicated a significant correlation between the degree of MK expression and MVD (P<0.001). These results suggest that MK may play important roles in malignant transformation and tumor angiogenesis in SGTs.

Metastatic renal cell carcinoma to the oral cavity and clear cell mucoepidermoid carcinoma: comparative clinicopathologic and immunohistochemical study.

BACKGROUND: Metastatic clear cell renal cell carcinoma (CCRCC) should be considered in differential diagnosis of intraoral clear cell tumors, including mucoepidermoid carcinoma (MEC). OBJECTIVE AND STUDY DESIGN: We compared the clinical, histologic, histochemical, and immunohistochemical characteristics of 9 oral metastatic CCRCCs and 8 intraoral clear cell MECs. RESULTS: Oral metastatic CCRCC affected salivary-gland containing tissues in 7 cases (78%). Microscopically, oral metastasis revealed a proliferation of neoplastic clear cells arranged in an alveolar pattern with central blood vessels, features that were not seen in any intraoral clear cell MEC. Mucicarmine staining was positive only in clear cell MEC. Immunohistochemistry showed similarities in cytokeratin expression; vimentin and CD10 were expressed in all oral metastatic CCRCCs but in only 1 clear cell MEC each. CONCLUSIONS: Besides clinical history, the alveolar pattern, vessel distribution, absence of mucicarmine staining, and vimentin and CD10 immunoexpression are useful in histologic differential diagnosis of CCRCC and clear cell MEC.

Morphometric analysis of CD34-positive vessels in salivary gland adenoid cystic and mucoepidermoid carcinomas.

BACKGROUND: Carcinomas of the salivary glands are uncommon and morphologically a diverse group of malignancies. To evaluate the prognostic value of CD34 immunostaining of the vessels in adenoid cystic carcinoma (AdCC) and mucoepidermoid carcinoma (MEC), an automated image analysis method was used. METHOD: In a nationwide study, covering salivary gland cancer (SGC) patients in Finland 1991-1996, 37 AdCC and 18 MEC patients (M 25, F 30, age 25-90, mean 63) were included. In addition to clinical characteristics the size, shape, staining intensity and vessel density in CD34 immunostained histologic samples were measured. RESULTS: Altogether 4433 vessels were measured from AdCC and 2615 from MEC tumor. Of the total tumor vessels measured, 2651 were from patients who deceased with disease (Group I) and 4397 were from specimens derived from those who did not die of disease (Group II) during the 10-year follow-up. The staining intensity was significantly higher in MEC than in AdCC tumor (P = 0.0005). In MEC, the Group I patients had a higher staining intensity among high-grade patients compared with patients with low grade disease, whereas the tumors in Group II had a lower staining intensity among the high-grade compared with the low grade tumors (P = 0.018). A higher vessel density was found in patients with MEC in group II compared with group I (P = 0.017). CONCLUSIONS: The staining intensity of CD34 positive vessels in MEC was higher than in AdCC. In MEC, higher staining intensity of vessels in high-grade tumors and lower vessel density in all MEC patients, predicted poor survival.

Tumor-associated macrophage correlated with angiogenesis and progression of mucoepidermoid carcinoma of salivary glands.

BACKGROUND: There is considerable controversy about whether tumor-associated macrophages (TAMs) promote or inhibit tumor progression. The present study examined the clinicopathologic significance of TAMs and their association with tumor angiogenesis, cell proliferation, and apoptosis in mucoepidermoid carcinoma (MEC). The potential effect of TAMs on cancer cells was also investigated. METHODS: CD68, CD34, Ki-67, and vascular endothelial growth factor (VEGF)-A immunohistochemical staining and terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling (TUNEL) were applied to samples from 41 MEC patients. The biologic effect of macrophages on MEC cancer cells was examined in a co-culture system. RESULTS: The proliferation index (PI) was 11.7+/-5.9%, and the apoptotic index (AI) was 4.1+/-2.3% in cancer patients. PI was significantly correlated with tumor grade, and the PI/AI ratio was significantly correlated with tumor size and stage. The distributions of intratumoral TAMs and microvessel density (MVD) were heterogeneous. TAM count associated strongly with tumor size, grading, and MEC staging. A greater intratumoral MVD was observed frequently in patients with large, intermediate/high-grade, and advanced-stage tumors. VEGF-A expression correlated significantly with tumor size and stage. MVD count was closely associated with TAM count and VEGF-A expression. Co-cultured cancer cells with macrophages increased migration and invasion ability of cancer cells. Co-cultured endothelial cells with cancer cells elevated VEGF-A expression, proliferation, and migration, and tube formation of endothelial cells. CONCLUSION: Our data suggest that TAMs play a tumor-promoting role in MEC. The TAM count, intratumoral MVD, and PI/AI ratio are potentially useful markers of progression in patients with MEC.

Correlation between the expression of thrombospondin-1 and neovascularization in mucoepidermoid carcinoma.

BACKGROUND: Researchers have recently demonstrated that thrombospondin-1 (TSP-1) has an important function in regulating neovascularization. Whether it inhibits or accelerates neovascularization, however, is still controversial. We found few reports about the correlation between TSP-1 and vascularization in mucoepidermoid carcinoma. In this research, the distribution and expression of TSP-1 in mucoepidermoid carcinoma were investigated. We also analyzed (1) the correlation between the expression of TSP-1 and microvessel density (MVD), as an indicator of neovascularization activity, and (2) the effect of TSP-1 on neovascularization and tumor growth in the subcutaneous xenotransplanted model of mucoepidermoid carcinoma. METHOD: (1) The sites and intensity of expression of TSP-1 and the MVD were analyzed in 45 cases of mucoepidermoid carcinoma after surgery by the method of streptavidin-peroxidase (SP) immunohistochemistry; and (2) recombinant human thrombospondin-1 (rhTSP-1) was injected twice a week for five consecutive weeks around the tumor in the subcutaneous xenotransplanted tumor model of mucoepidermoid carcinoma in nude mice. Each week, the tumor size was measured, in order to draw the growth curve of the xenotransplanted tumor model of mucoepidermoid carcinoma, and MVD was measured. RESULTS: (1) The positive expression of TSP-1 protein was 57.78% (26/45). Most positive staining for TSP-1 was found in the cytoplasm of the cancer cells, while some staining occurred in the extracellular matrix. The mean MVD in 45 cases of mucoepidermoid carcinoma was 58.17 +/- 19.77 per 100 visual fields. Tumors with a high expression of TSP-1 showed a low MVD value, and the TSP-1 immunocompetence and microvessel density showed a significant negative correlation (r(s) = -0.947, P < 0.001). (2) The xenotransplanted tumors with the injection doses of 1.25, 0.75 and 0.25 microg/ml respectively were 36.97%, 53.36% and 73.61% of the size of the control group ((451 +/- 92), (651 +/- 113), (898 +/- 86) and (1220 +/- 157) mm(3) respectively, F = 53.167, P < 0.001), and their weights were respectively 35.14%, 51.35% and 70.27% of the control group ((1.3 +/- 0.5), (1.9 +/- 0.5), (2.6 +/- 0.3), and (3.7 +/- 0.7) g respectively, F = 62.669, P < 0.001). Their MVDs were 25.00%, 45.93%, and 72.20% respectively of the control group and concentration dependent (15.43 +/- 3.45, 28.35 +/- 4.24, 44.57 +/- 3.35 and 61.73 +/- 5.43 per 100 visual fields respectively, F = 54.582, P < 0.001). CONCLUSIONS: The TSP-1 has a higher expression in mucoepidermoid carcinoma and the expression has a significant negative correlation with neovascularization. The TSP-1 inhibits neovascularization and tumor growth, and it might be a new biological therapy for treatment of patients with mucoepidermoid carcinoma.

[Correlation between the expression of thrombospondin-1 and the angiogenesis in mucoepidermoid carcinoma].

OBJECTIVE: To study the relationship between the expression of thrombospondin-1 (TSP-1) and the angiogenesis in mucoepidermoid carcinoma. METHODS: Immunohistochemistry were applied to detect the expression of TSP-1 and the value of microvessel density (MVD) in 45 mucoepidermoid carcinoma patients. RESULTS: Positive expressions of TSP-1 protein were detected in 26 of the 45 (57. 78%) cases. Most positive staining for TSP-1 was observed in the cytoplasm of the cancer cells, some of those were in the extracellular matrix. The mean MVD in 45 cases with mucoepidermoid carcinoma was 60. 68 +/- 19.84 vessels per 100 field of vision. Tumors with a high expression of TSP-1 showed a low value of MVD and the correlation between TSP-1 immunocompetence and microvessel density was highly significant (r(s) = -0.942, P < 0.001). CONCLUSION: The TSP-1 is expressed in most mucoepidermoid carcinoma and were associated with neovascularization. TSP-1 is likely to inhibit the extensive neovascularization and increased TSP-1 expression might inhibit angiogenic phenotype in mucoepidermoid carcinoma.

Expression of caveolin-1 in mucoepidermoid carcinoma of the salivary glands: correlation with vascular endothelial growth factor, microvessel density, and clinical outcome.

BACKGROUND: Caveolin-1, which has been proposed as a candidate tumor suppressor, plays a regulatory role in several signaling pathways. The importance of caveolin-1 in endothelial cells in angiogenesis has been confirmed. The clinicopathologic significance of caveolin-1 expression and its correlation with angiogenesis remains unknown in mucoepidermoid carcinoma (MEC) of the salivary glands. METHODS: Based on an immunohistochemical study, the expression levels of caveolin-1 and vascular endothelial growth factor (VEGF) and the intratumoral microvessel density (MVD) (labeled by CD34) in 75 patients with MEC were investigated, and correlations with clinicopathologic variables were evaluated statistically. RESULTS: The expression rates of both caveolin-1 and VEGF were 54.7% (41 of 75 tumors). MVD varied from 9 to 56 (24.45 +/- 10.72)/x 200. Caveolin-1 expression was correlated inversely with duration of tumor, clinical stage, histologic grade, and MVD (P = .027, P = .011, P = .04, and P = .025; respectively). VEGF expression was associated positively with MVD (P = .000). Advanced clinical stage, higher grade, and tumors that originated from minor salivary glands exhibited higher MVD (P = .029, P = .002, and P = .008, respectively). The presence of clinical symptoms, male gender, advanced clinical stage, higher grade, increased MVD, and down-regulated caveolin-1 were correlated significantly with the development of recurrent disease, as indicated by a shorter disease-free interval (P < .05). Both univariate and multivariate analyses indicated that clinical stage, histologic grade, and MVD were independent prognostic factors (P < .05). The presence of clinical symptoms and the down-regulation of caveolin-1 were identified as negative prognostic predictors in the univariate analysis (P < .05) but did not achieve significance in the multivariate analysis (P > .05). CONCLUSIONS: The current results suggest that caveolin-1 may function as a tumor suppressor in MEC of the salivary glands. Reduced expression of caveolin-1 and increased MVD may indicate a poor prognosis for certain patients.

Hypoxia-induced angiogenesis of cultured human salivary gland carcinoma cells enhances vascular endothelial growth factor production and basic fibroblast growth factor release.

The angiogenic activity of two human salivary gland tumor cell lines, ACCS from adenoid cystic carcinoma and IT-2 from mucoepidermoid carcinoma, was examined by stimulating tube formation by bovine capillary endothelial cells (BCE). ACCS and IT-2 were cultured in 20 or 3% oxygen, representing normoxic and hypoxic conditions, respectively, and conditioned medium (CM) was obtained from each culture. The BCE tubes stimulated by hypoxic CM were 1.59 (ACCS) and 1.42 (IT-2) times longer than those stimulated by normoxic CM. The tube-forming activity of CM was inhibited by preincubation with either anti-vascular endothelial growth factor (VEGF) IgG or anti-basic fibroblast growth factor (bFGF) IgG, suggesting that both VEGF and bFGF with angiogenic activity were present in the CM. This was confirmed by ELISA, which also demonstrated increased concentrations of both proteins in the hypoxic CM. Northern blot analysis showed an increased VEGF mRNA level in both carcinoma cells with hypoxia, while hypoxia did not affect the bFGF mRNA level in either cell line. The results suggest that both VEGF and bFGF are major angiogenesis factors in salivary gland tumors, and hypoxia-induced angiogenesis results from upregulation of VEGF and increased release of bFGF.

Expression of p53 oncoprotein increases intratumoral microvessel formation in human salivary gland carcinomas.

P53 protein and vascular endothelial growth factor (VEGF) expression, and mean intratumoral microvessel density (IMVD) were studied by immunohistochemistry in 31 salivary gland carcinomas, consisting of 11 adenoid cystic carcinomas (AdCCs), 10 mucoepidermoid carcinomas (MECs), 7 acinic cell carcinomas (AcCCs), and 3 squamous cell carcinomas (SCCs). Cases with p53 protein in more than 20% of tumor cells were detected in one AdCC, four MECs, one AcCC, and two SCCs. Both frequency of p53 and VEGF expression, and mean IMVD, were higher in the MECs and SCCs than in the AdCCs and AcCCs. Similarly, both VEGF expression and mean IMVD were significantly higher (P<0.05) in the eight p53-positive tumors than in the 23 negative tumors. Six cases with survival periods less than 5 years showed significantly higher frequency of p53 and VEGF expression and of mean IMVD than those with longer survival periods. These results indicate that p53 expression might partly correlate with VEGF expression and mean IMVD, and be a factor in the survival of patients with salivary gland carcinomas.