Tumour micrometastases: the influence of angiogenesis

Iodine map histogram metrics in early-stage breast cancer: prediction of axillary lymph node metastasis status

BACKGROUND

Variations in axillary lymph node (ALN) metastatic potential between different breast cancers lead to microscopical alterations in tumor perfusion heterogeneity. This study investigated the usefulness of histogram metrics from iodine maps in the preoperative diagnosis of metastatic ALNs in patients with early-stage breast cancer.

METHODS

Between October 2020 and November 2021 enhanced spectral computed tomography (CT) was performed in female patients with breast cancer. Quantitative spectral CT parameters and histogram parameters (mean, median, maximum, minimum, 10th percentiles, 90th percentiles, kurtosis, skewness, energy, range, and variance) from iodine maps were compared between patients with metastatic and nonmetastatic ALNs. Continuous variables were compared using Student's t-test or Mann-Whitney U test. Categorical variables were compared using Pearson's chi-square tests or Fisher's exact tests. Associations between ALN status and imaging features were evaluated using Mann-Whitney U test and receiver operating characteristic (ROC) curve analysis.

RESULTS

This study included 113 female patients (62 and 51 in the ALN-negative and ALN-positive groups, respectively). Tumor size, molecular subtypes, and location differed significantly between the ALN-negative and ALN-positive groups (P<0.05). None of the quantitative spectral CT parameters of mass between metastatic and nonmetastatic ALN groups were significantly different (P>0.05). Histogram parameters of iodine maps for breast cancers, including maximum, 10th percentile, range, and energy, were significantly higher in the metastatic ALNs group compared with the nonmetastatic ALNs group (P<0.05). Multivariable logistic regression analyses showed that tumor location and energy were independent predictors of metastatic ALNs in breast cancers. The combination of independent predictors yielded an area under the curve (AUC) of 0.824 (sensitivity 72.5%; specificity 74.2%).

CONCLUSIONS

Whole-lesion histogram parameters derived from spectral CT iodine maps may be used as a complementary noninvasive means for the preoperative identification of ALN metastases in patients with early-stage breast cancer.

Oesophageal cancer metastases: An observational study of a more aggressive approach

BACKGROUND

The prognosis for oesophageal carcinoma is poor, but once distant metastases emerge the prognosis is considered hopeless. There is no consistent protocol for the early identification and aggressive management of metastases.

AIM

To examine the outcome of a policy of active postoperative surveillance with aggressive treatment of confirmed metastases.

METHODS

A prospectively maintained database of 205 patients diagnosed with oesophageal carcinoma between 1998 and 2019 and treated with curative intent was interrogated for patients with metastases, either at diagnosis or on follow-up surveillance and treated for cure. This cohort was compared with incomplete clinical responders to neoadjuvant chemoradiotherapy (nCRT) who subsequently underwent surgery on their primary tumour. Overall survival was estimated using the Kaplan-Meier method, and the log-rank test was used to compare survival differences between groups.

RESULTS

Of 205 patients, 11 (5.4%) had metastases treated for cure (82% male; median age 60 years; 9 adenocarcinoma and 2 squamous cell carcinomas). All had undergone neoadjuvant chemotherapy or chemoradiotherapy, followed by surgery in all but 1 case. Of the 11 patients, 4 had metastatic disease at diagnosis, of whom 3 were successfully downstaged with nCRT before definitive surgery; 2 of these 4 also developed oligometastatic recurrence and were treated with curative intent. Following definitive treatment, 7 had treatment for metachronous oligometastatic disease; 5 of whom underwent metastasectomy (adrenal × 2; lung × 2; liver × 1). The median overall survival was 10.9 years [95% confidence interval (CI): 0.7-21.0 years], which was statistically significantly longer than incomplete clinical responders undergoing surgery on the primary tumour without metastatic intervention [n = 62; median overall survival = 1.9 (95%CI: 1.1-2.7; P = 0.012]. The cumulative proportion surviving 1, 3, and 5 years was 100%, 91%, and 61%, respectively compared to 71%, 36%, and 25% for incomplete clinical responders undergoing surgery on the primary tumour who did not undergo treatment for metastatic disease.

CONCLUSION

Metastatic oesophageal cancer represents a unique challenge, but aggressive treatment can be rewarded with impressive survival data. In view of recent advances in targeted therapies, intensive follow-up may yield a greater number of patients with curative potential and thus improved long-term survival.

Targeting Intercellular Communication in the Bone Microenvironment to Prevent Disseminated Tumor Cell Escape from Dormancy and Bone Metastatic Tumor Growth

Metastasis to the bone is a common feature of many cancers including those of the breast, prostate, lung, thyroid and kidney. Once tumors metastasize to the bone, they are essentially incurable. Bone metastasis is a complex process involving not only intravasation of tumor cells from the primary tumor into circulation, but extravasation from circulation into the bone where they meet an environment that is generally suppressive of their growth. The bone microenvironment can inhibit the growth of disseminated tumor cells (DTC) by inducing dormancy of the DTC directly and later on following formation of a micrometastatic tumour mass by inhibiting metastatic processes including angiogenesis, bone remodeling and immunosuppressive cell functions. In this review we will highlight some of the mechanisms mediating DTC dormancy and the complex relationships which occur between tumor cells and bone resident cells in the bone metastatic microenvironment. These inter-cellular interactions may be important targets to consider for development of novel effective therapies for the prevention or treatment of bone metastases.

Correlation of microvessel parameters in invasive ductal carcinoma of the breast and fibroadenomas: a morphometric study

Modifications of microvascular configuration are essential features encountered during the progression of breast tumors. Our objectives were to correlate morphometrically evaluated microvessel parameters (microvessel density [MVD], microvessel caliber [VC], microvessel cross-sectional area [VCSA], percentage of total VCSA [%TVCSA], and total microvessel boundary density [TVBD]) with histologic grades of invasive ductal carcinoma (IDC) of the breast and benign breast lesions. Sixty cases of IDC presented with modified radical mastectomy, and 20 benign breast fibroadenomas were evaluated for various microvessel parameters, using CD34-immunostained histologic sections by computerized image morphometry. Samples were divided into 4 histologic groups: benign, grade 1, grade 2, and grade 3; mean with SD and range was evaluated for each group. Histologic grades showed a strong positive correlation with %TVCSA (ρ=0.773) and TVBD (ρ=0.811) and a moderate positive correlation with MVD (ρ=0.607), VC (ρ=0.609), and VCSA (ρ=0.616) when analyzed for all samples of the 4 groups. Except MVD, all parameters including age was the lowest (P<.001) for the benign group. Among the IDCs, differences of mean VC and VCSA were not significant; MVD, %TVCSA, and TVBD were the lowest in grade 1 and the highest in grade 3. Upper cutoff value of benign lesions for MVD was 155mm^-2; VC, 9.94μm; VCSA, 94.42 μm²; %TVCSA, 1.33; and TVBD, 4.37mm^-1. Total microvessel boundary density included the information of microvessel concentration and size showed the best correlation with grades. Microvessel density showed a positive correlation with grades in the IDCs, but for the differentiation of benign from malignant, VC, VCSA, %TVCSA, and TVBD showed excellent area under the receiver operating characteristic curve (area under the curve > 0.990), unlike MVD (area under the curve = 0.797).

Contrast enhanced computed tomography is indicative for angiogenesis pattern and display prognostic significance in breast cancer

Background

The Prognostic value of microvessel density in cancer remains unclear. Recent studies have suggested that the uneven distribution of microvessels in tumours caused the variation in sample selection which led to different prognostic outcome. The enhancement pattern of Contrast-enhanced computed tomography (CECT) is determined in part by the microvessel distribution in solid tumors. Therefore, survival analysis of tumors grouping by the enhancement pattern and the pattern of microvessel distribution is important.

Methods

Survival analysis grouped by the tumor enhancement pattern and the microvessel distribution was carried out in 255 patients with invasive ductal carcinoma.

Results

There were significant differences in overall survival (OS) and disease-free survival (DFS) among the homogeneous, heterogeneous and peripheral enhancement groups. There were significant differences between OS and DFS groups with uniform and uneven distributions of microvessels.

Conclusions

The distribution of microvessels in a tumor is a potential prognostic indicator in patients with breast cancer, and can be assessed by CECT prior the operation.

The clinical impact of mean vessel size and solidity in breast carcinoma patients

Angiogenesis quantification, through vessel counting or area estimation in the most vascular part of the tumour, has been found to be of prognostic value across a range of carcinomas, breast cancer included. We have applied computer image analysis to quantify vascular properties pertaining to size, shape and spatial distributions in photographed fields of CD34 stained sections. Aided by a pilot (98 cases), seven parameters were selected and validated on a separate set from 293 breast cancer patients. Two new prognostic markers were identified through continuous cox regression with endpoints breast cancer specific survival and distant disease free survival: The average size of the vessels as measured by their perimeter (p = 0.003 and 0.004, respectively), and the average complexity of the vessel shapes measured by their solidity (p = 0.004 and 0.004). The Hazard ratios for the corresponding median-dichotomized markers were 2.28 (p = 0.005) and 1.89 (p = 0.016) for the mean perimeter and 1.80 (p = 0.041) and 1.55 (p = 0.095) for the shape complexity. The markers were associated with poor histologic type, high grade, necrosis, HR negativity, inflammation, and p53 expression (vessel size only). Both markers were found to strongly influence the prognostic properties of vascular invasion (VI) and disseminated tumour cells in the bone marrow. The latter being prognostic only in cases with large vessels (p = 0.004 and 0.043) or low complexity (p = 0.018 and 0.024), but not in the small or complex vessel groups (p>0.47). VI was significant in all groups, but showed greater hazard ratios for small and low complexity vessels (6.54-11.2) versus large and high complexity vessels (2.64-3.06). We find that not only the overall amount of produced vasculature in angiogenic hot-spots is of prognostic significance, but also the morphological appearance of the generated vessels, i.e. the size and shape of vessels in the studied hot spots.

A flavonoid chrysin suppresses hypoxic survival and metastatic growth of mouse breast cancer cells

Tumor hypoxia commonly occurs in solid tumors, and correlates with metastasis. Current cancer therapies are inefficient in curing metastatic disease. Herein, we examined effect of Thai propolis extract and its major constituent, chrysin, on hypoxic survival of 4T1 mouse breast cancer cells in vitro, and investigated its underlying mechanism. In vivo effect of chrysin on metastatic progression of cancer cells was studied, both as a single agent and in combination with another antimetastatic agent, agonistic monoclonal antibody targeting the DR5 TRAIL receptor (DR5 mAb). Thai propolis extract and chrysin decreased survival of 4T1 cells after exposure to hypoxia (1% O2), for 2 days. Immunoblot analysis revealed that chrysin inhibited hypoxia-induced STAT3 phosphorylation without affecting HIF-1α protein level. Chrysin also abrogated hypoxia-induced VEGF gene expression as determined by qRT-PCR. The in vivo effect of chrysin was determined in a spontaneous metastasis mouse model of breast cancer, either alone or in combination with DR5 mAb. Daily oral administration of chrysin in Balb/c mice implanted with 4T1 cells significantly suppressed growth of lung metastatic colonies. Moreover, antimetastatic activity of DR5 mAb was enhanced when given in combination with chrysin. We demonstrate that chrysin has potential in controlling metastatic progression.

Targeting therapy for esophageal cancer in patients aged 70 and over

BACKGROUND

While cancer is a disease of the elderly, these patients are under-represented in randomized trials. Esophageal cancer-management in the elderly is challenging because of the morbidity and mortality associated with surgery.

OBJECTIVES

We examined a strategy of neo-adjuvant chemo-radiotherapy (naCRT), followed by surgery or surveillance, in selected patients with cancer aged 70 and older.

METHODS

A prospectively-accrued database identified 56 consecutive patients over a 90-month period, who were aged 70years and over, presented with esophageal carcinoma and were treated with neo-adjuvant CRT (naCRT)±surgery.

RESULTS

Of 129 eligible patients, 66 (51%) received palliative measures, while 63 (49%) had curative intervention, namely 7 had surgery and 56 had naCRT±surgery. Of these 56 patients, 33 (59%) had adenocarcinoma (AC) and 23 (41%) had squamous cell carcinoma (SCC). Twenty-five (45%) had a complete clinical response (cCR), of which 6 had immediate resection; 4 (67%) had a complete pathological response (pCR); 19 patients with a cCR declined or were unfit for surgery and underwent surveillance; of these, 3 had interval esophagectomy; 16 were not offered or declined resection. Eight (50%) have survived ≥3years. Mean overall survival was 28months for the entire cohort; 47months for cCRs; 61months for patients undergoing primary resection, 46months for cCRs who did not undergo resection and 29months for those undergoing interval resection for recurrent disease. In cCRs, surgery did not provide a survival advantage (p=0.861).

CONCLUSION

cCR yields an overall 3-year survival of 50% without operation. As 45% of patients have a cCR to naCRT, obligatory resection in high-risk cCR patients makes little sense. With the option for salvage esophagectomy in re-emergent disease, this selective strategy is an attractive alternative for elderly patients with cancer.

Bone marrow micrometastases in esophageal carcinoma: a 10-year follow-up study

Detection of bone marrow micrometastases (BMMs) in patients with esophageal carcinoma may indicate a metastatic phenotype. We assessed if the presence of BMMs had adverse prognostic significance in a 10-year follow-up study. Patients undergoing surgery for esophageal cancer were prospectively recruited between February 1999 and August 2000. Bone marrow aspirates were obtained from the iliac crest of patients under general anesthesia at the time of surgery. Immunocytochemical analysis using anticytokeratin antibodies CAM 5.2 and AE1/AE3 was undertaken to determine the presence of BMMs. Union International Contre le Cancer staging was recorded for all patients. Patient follow-up was completed over a 10-year period through analysis of the Northern Ireland Cancer Registry. Forty-two patients (male = 35) were included, with a mean age of 67.2 years (range 39-83). BMMs were detected in 19 patients (45.2%). International Contre le Cancer tumor staging was stage I = 6, stage II = 10, stage III = 24, and stage IV = 2. BMMs were associated with lymphovascular invasion (P= 0.02) and advanced T stage (P= 0.02). Overall, 10-year survival was 21.4% (n= 9), with a median follow-up of 877.5 days (interquartile range 391.5-2546.3). There was no statistically significant difference between the survival of patients with or without BMMs (1451.4 vs. 1431.6 days, P= 0.99). Univariate analysis demonstrated a trend toward decreased survival for patients with positive lymph nodes (P= 0.07), an increased T stage (P= 0.06), and lymphovascular invasion (P= 0.07). Multivariate analysis demonstrated that none of the variables were significant predictors of mortality. Although the presence of BMMs correlates with recognized adverse tumor characteristics in patients with esophageal cancer, micrometastases detected in the bone marrow at time of surgery does not influence long-term survival.

Design, synthesis, and biological evaluation of dibromotyrosine analogues inspired by marine natural products as inhibitors of human prostate cancer proliferation, invasion, and migration

Bioactive secondary metabolites originating from dibromotyrosine are common in marine sponges, such as sponges of the Aplysina species. Verongiaquinol (1), 3,5-dibromo-1-hydroxy-4-oxocyclohexa-2,5-diene-1-acetamide, and aeroplysinin-1 are examples of such bioactive metabolites. Previous studies have shown the potent antimicrobial as well as cytotoxic properties of verongiaquinol and the anti-angiogenic activity of aeroplysinin-1. The work presented herein shows the design and synthesis of dibromotyrosine-inspired phenolic ester and ether analogues with anti-angiogenic, anti-proliferative and anti-migratory properties and negligible cytotoxicity. Several analogues were synthesized based on docking experiments in the ATP binding site of VEGFR2 and their anti-angiogenic potential and ability to inhibit angiogenesis and prostate cancer proliferation, migration and invasion were evaluated using the chick chorioallantoic membrane (CAM) assay, MTT, wound-healing, and Cultrex® BME cell invasion assay models, respectively. Analogues with high docking scores showed promising anti-angiogenic activity in the CAM assay. In general, ester analogues (5, 6, and 8-10) proved to be of higher anti-migratory activity whereas ether analogues (11-14) showed better anti-proliferative activity. These results demonstrate the potential of dibromotyrosines as promising inhibitory scaffolds for the control of metastatic prostate cancer proliferation and migration.

Distribution of fluorescent microspheres in vascular space and parenchymal organs of intact nude rats

PURPOSE

To assess kinetics of elimination of different sized microspheres (MS) from the blood pool and tendency of their distribution in parenchymal organs of intact nude rats.

MATERIALS AND METHODS

A mixture of 1 microm and 3 microm MS in phosphate-buffered saline was injected intravenously into eight rats under intraperitoneal anaesthesia. Blood samples were collected before, just after and in 2, 5 and 10 min after MS injection. Dynamics of MS elimination from blood pool was evaluated with flow cytometry. After euthanasia, histological sections were prepared and distributions of MS through the liver, spleen, kidney and lung were analysed with fluorescence microscopy and flow cytometry.

RESULTS

The number of microspheres registered in the intravascular space showed a marked exponential decrease over time independent of MS size. Different amounts and proportions of 1 microm and 3 microm MS were revealed in lung, liver, spleen and kidneys of the rats. Most of 1 microm MS were localised in liver and spleen. In contrast, 3 microm MS were detected predominantly in lung.

CONCLUSION

1 microm and 3 microm MS may be assumed as free circulating particles only for a short period of time after injection. Their elimination kinetics seems to be tightly linked to specific tissue properties such a pulmonary vasoconstriction and phagocytosis.

Endothelial cells expressing Bcl-2 promotes tumor metastasis by enhancing tumor angiogenesis, blood vessel leakiness and tumor invasion

Metastatic spread of tumor cells to vital organs is the major cause of mortality in cancer patients. Bcl-2, a key antiapoptotic protein, is expressed at high levels in a number of human tumors. We have recently shown that Bcl-2 is also overexpressed in tumor-associated blood vessels in head-and-neck cancer patients. Interestingly, enhanced Bcl-2 expression in tumor blood vessels is directly correlated with metastatic status of these cancer patients. In addition, endothelial cells (ECs) expressing Bcl-2 showed increased production of interleukin-8 (IL-8) resulting in significantly enhanced tumor cell proliferation and tumor cell invasion. Therefore, we hypothesized that Bcl-2 expression in tumor-associated ECs may promote tumor metastasis by enhancing tumor cell invasiveness and release in the circulation. To test our hypothesis, we coimplanted tumor cells along with ECs expressing Bcl-2 (EC-Bcl-2) in the flanks of SCID mice. Our results demonstrate that incorporation of EC-Bcl-2 in primary tumors significantly enhanced tumor cell metastasis to lungs and this EC-Bcl-2-mediated tumor metastasis was independent of primary tumor size. In addition, Bcl-2-mediated tumor metastasis directly correlated with increased tumor angiogenesis. Bcl-2 expression in ECs also promoted transendothelial cell permeability, blood vessel leakiness and tumor cell invasion. EC-Bcl-2-mediated tumor cell proliferation and tumor cell invasion were significantly mediated by IL-8. These results suggest that Bcl-2, when expressed at higher levels in tumor-associated ECs, may promote tumor metastasis by enhancing tumor angiogenesis, blood vessel leakiness and tumor cell invasiveness.

The tumor microenvironment and metastatic disease

The microenvironment of solid tumors is a heterogeneous, complex milieu for tumor growth and survival that includes features such as acidic pH, low nutrient levels, elevated interstitial fluid pressure (IFP) and chronic and fluctuating levels of oxygenation that relate to the abnormal vascular network that exists in tumors. The metastatic potential of tumor cells is believed to be regulated by interactions between the tumor cells and their extracellular environment (extracellular matrix (ECM)). These interactions can be modified by the accumulation of genetic changes and by the transient alterations in gene expression induced by the local tumor microenvironment. Clinical and experimental evidence suggests that altered gene expression in response to the hypoxic microenvironment is a contributing factor to increased metastatic efficiency. A number of genes that have been implicated in the metastatic process, involving angiogenesis, intra/extravasation, survival and growth, have been found to be hypoxia-responsive. The various metastatic determinants, genetic and epigenetic, somatic and inherited may serve as precedents for the future identification of more genes that are involved in metastasis. Much research has focused on genetic and molecular properties of the tumor cells themselves. In the present review we discuss the epigenetic and physiological regulation of metastasis and emphasize the need for further studies on the interactions between the pathophysiologic tumor microenvironment and the tumor extracellular matrix.

Vascularization in primary breast carcinomas: its prognostic significance and relationship with tumor cell dissemination

PURPOSE

The interaction between tumor cells, stroma, and endothelial cells is important for the dissemination of tumor cells. The aim of the present study is to examine vascularity in primary breast carcinomas and its prognostic significance and relationship with tumor cell dissemination.

EXPERIMENTAL DESIGN

A total of 498 invasive breast carcinomas were analyzed. Representative tumor sections were stained for CD34 and CD105, and vascularity was quantified by the Chalkley method. The relationship between Chalkley counts, vascular invasion, disseminated tumor cells (DTC) in the bone marrow, other clinicopathologic variables, and clinical outcome was evaluated.

RESULTS

High vascular grades determined by Chalkley counts were significantly associated with shorter distant disease-free survival and breast cancer-specific survival in all patients (P < 0.001, log-rank) and in node-negative patients not receiving adjuvant systemic therapy (P < 0.05). In multivariate analysis, both CD34 and CD105 Chalkley counts showed prognostic significance for distant disease-free survival (P = 0.014 and P = 0.026), whereas CD34 also showed prognostic significance for breast cancer-specific survival (P = 0.007). Vascular invasion and DTCs in the bone marrow showed independent prognostic significance. DTC did not discriminate survival for CD34 low Chalkley counts, whereas a very poor prognosis was observed for DTC-positive patients with high CD34 counts. In node-negative patients not receiving systemic chemotherapy, high CD34 and high CD105 counts in combination identified patients with unfavorable outcome, as opposed to all other CD34/CD105 combinations.

CONCLUSIONS

Improved identification of risk groups could be obtained by adding CD34 and CD105 vascular analysis to DTC, vascular invasion, and other primary tumor factors. This may facilitate the selection of candidates for adjuvant systemic therapy.

Relationship between vascular invasion and microvessel density and micrometastasis

AIM

To evaluate the relationship between vascular invasion and microvessel density (MVD) of tissue and micrometastasis in blood.

METHODS

Vascular invasion was detected by both hematoxylin and eosin staining and immunohistochemiscal staining. Blood samples were collected from 17 patients with vascular invasion and 29 patients without vascular invasion and examined for cytokeratin20 (CK20) expression by reverse transcriptase-polymerase chain reaction (RT-PCR) analysis. Microvessel density of tissue samples was also determined by immunohistochemistry using antibodies to CD105.

RESULTS

CK20 was detected in 12 of the 17 patients with vascular invasion and in 9 of the 29 patients without vascular invasion. Positive RT-PCR was significantly correlated with vascular invasion (70.6% vs 30.0%, P < 0.05). The average MVD was significantly higher in patients with positive vascular invasion than in patients with negative vascular invasion (29.2 +/- 3.3 vs 25.4 +/- 4.7, P < 0.05). The vascular invasion detected with hematoxylin-eosin staining was less than that with immunohistochemical staining. There was a significant difference between the two staining methods (19.6% vs 36.9%, P < 0.05).

CONCLUSION

Positive CK20 RT-PCR, depth of tumor invasion, lymph node status, metastasis and MVD are significantly correlated with vascular invasion. Immunohistochemical staining is more sensitive than hematoxylin-eosin staining for detecting vascular invasion.

Relationship between vascular invasion and microvessel density and micrometastasis

AIM: To evaluate the relationship between vascular invasion and microvessel density (MVD) of tissue and micrometastasis in blood.

METHODS: Vascular invasion was detected by both hematoxylin and eosin staining and immunohistochemiscal staining. Blood samples were collected from 17 patients with vascular invasion and 29 patients without vascular invasion and examined for cytokeratin20 (CK20) expression by reverse transcriptase-polymerase chain reaction (RT-PCR) analysis. Microvessel density of tissue samples was also determined by immunohistochemistry using antibodies to CD105.

RESULTS: CK20 was detected in 12 of the 17 patients with vascular invasion and in 9 of the 29 patients without vascular invasion. Positive RT-PCR was significantly correlated with vascular invasion (70.6% vs 30.0%, P < 0.05). The average MVD was significantly higher in patients with positive vascular invasion than in patients with negative vascular invasion (29.2 ± 3.3 vs 25.4 ± 4.7, P < 0.05). The vascular invasion detected with hematoxylin-eosin staining was less than that with immunohistochemical staining. There was a significant difference between the two staining methods (19.6% vs 36.9%, P < 0.05).

CONCLUSION: Positive CK20 RT-PCR, depth of tumor invasion, lymph node status, metastasis and MVD are significantly correlated with vascular invasion. Immunohistochemical staining is more sensitive than hematoxylin-eosin staining for detecting vascular invasion.

Hypoxia enhances metastatic efficiency in HT1080 fibrosarcoma cells by increasing cell survival in lungs, not cell adhesion and invasion

This study examined possible mechanisms for hypoxia-increased metastasis in a green fluorescent protein-labeled human fibrosarcoma cell line (HT1080). The efficiency of the lung arrest of tumor cells, which can be dependent on the adhesive potential of the tumor cells, was assessed by measuring the level of integrin alpha3beta1 protein and by adhesion assays, whereas the extravasation potential was examined by an invasion assay. These properties were not changed by exposure to hypoxia, indicating that lung arrest and extravasation are unlikely to play a major role in the effect of hypoxia on metastasis in this model. The main effect of hypoxic exposure was found to be increased survival after lung arrest as determined by clonogenic assay of tumor cells recovered from mouse lungs after i.v. injection. Concomitantly, apoptosis was identified as responsible for the death of lung-arrested cells, suggesting the involvement of an altered apoptotic response following hypoxic exposure of these cells. Consistent with this finding, we found that the effect of hypoxia on both increased metastasis and survival of arrested cells was inhibited by treatment with farnesylthiosalicylic acid. However, this effect was not due to down-regulation of hypoxia-inducible factor-1alpha, a mechanism of action of this drug reported by previous studies. Further detailed studies of the mechanisms of action of the drug are needed.

Anti-angiogenic gene therapy of cancer: current status and future prospects

The discovery of endogenous inhibitors of angiogenesis has made it possible to test the hypothesis that blocking the angiogenic switch may keep tumor growth in check, and has added a new investigational arm to the field of cancer gene therapy. Angiogenesis inhibitors are heterogeneous in origin and potency, and their growing list includes proteolysis products of larger molecules with a different function, such as angiostatin, endostatin and vasostatin, modulators of vascular endothelial growth factor activity, such as sFLT-1, and some cytokines/chemokines with marked anti-endothelial activity, such as IL-12, IFN-alpha, and CXCL10. Pre-clinical studies have clearly indicated that these factors are essentially cytostatic and that they need long-term administration in order to obtain prolonged anti-tumor effects, representing a rational basis for their delivery by a gene therapy approach. The experimental approaches attempted to date, reviewed herein, indicate overall that anti-angiogenic gene therapy has efficacy mainly as an early intervention strategy and that a better understanding of the biological mechanisms underlying resistance to angiogenesis inhibition, as well as appropriate combined treatments, are required to generate a conceptual advancement which could drive the field towards successful management of established tumors.

Preventive effect of oral administration of 6-(methylsulfinyl)hexyl isothiocyanate derived from wasabi (Wasabia japonica Matsum) against pulmonary metastasis of B16-BL6 mouse melanoma cells

AIM

Effect of oral administration of 6-(methylsulfinyl)hexyl isothiocyanate (6-MITC) or a 6-MITC-containing T-wasabi fraction from wasabi root (Wasabia japonica Matsum) to inhibit the macroscopic pulmonary metastasis was studied with a murine B16-BL6 melanoma model.

METHOD

Two administration routes, subcutaneous or intravenous, and two administration times, prior to or concomitant with tumor inoculation, of 6-MITC or T-wasabi against the metastatic foci formation in C57BL/6J mouse lungs were compared.

RESULTS

The number of metastasized foci per lung in either subcutaneous or intravenous injection was significantly reduced by intake of 6-MITC or a T-wasabi fraction. The maximum reduction by a T-wasabi fraction reached to 82%. Fifty-six percent of foci formation was inhibited by a 2 week-prior administration of 6-MITC (200 microM), whereas only 27% inhibition was obtained by a concomitant administration with tumor inoculation. Neither 6-MITC nor T-wasabi at tested concentrations showed any toxic effects.

DISCUSSION

Together with our previous results, a component of the Japanese pungent spice, wasabi appears to inhibit not only tumor cell growth but also tumor metastasis. Therefore, 6-MITC from wasabi is apparently a useful dietary candidate for controlling tumor progression.

Bone Marrow Micrometastases and Markers of Angiogenesis in Esophageal Cancer

BACKGROUND

Tumor angiogenesis is critical for metastasis development. The detection of bone marrow micrometastases may indicate a metastatic phenotype. We aim to establish if the detection of bone marrow micrometastases associates with elevated markers of angiogenesis and adverse histopathologic features of esophageal cancer.

METHODS

Bone marrow aspirates from 49 patients with esophageal cancer were assessed and assigned to be positive or negative for micrometastases. Routine histologic assessment of the primary tumor was also undertaken. Circulating and tumor levels of the angiogenic cytokine vascular endothelial growth factor were determined in plasma and tumor homogenate. Intratumor microvessel density was evaluated by counting anti-CD34 positive neovessels.

RESULTS

Twenty-two patients were positive for bone marrow micrometastases (44.9%). The detection of micrometastases was associated with advanced T stage (T3/4 vs T1/2; p = 0.023), circumferential margin involvement (p = 0.002) and lymphovascular invasion (p = 0.024). Plasma vascular endothelial growth factor was significantly more elevated in micrometastatic-positive patients than in those without micrometastases (p = 0.018). No difference was noted in tumor vascular endothelial growth factor expression. For adenocarcinomas alone, intratumor microvessel density was significantly higher in micrometastatic positive cases (p = 0.03). This was not the case for squamous cell carcinomas.

CONCLUSIONS

The detection of bone marrow micrometastases is associated with esophageal tumors of advanced T stage and specifically for adenocarcinomas with tumor vascularity. Plasma vascular endothelial growth factor is elevated in micrometastatic positive cases and might be derived from sources other than the primary tumor.

2-Hydroxy-4,6-diamino-[1,3,5]triazines: A Novel Class of VEGF-R2 (KDR) Tyrosine Kinase Inhibitors

2-Hydroxy-4,6-diamino-[1,3,5]triazines are described which are a novel class of potent inhibitors of the VEGF-R2 (flk-1/KDR) tyrosine kinase. 4-(Benzothiazol-6-ylamino)-6-(benzyl-isopropyl-amino)-[1,3,5]triazin-2-ol (14d) exhibited low nanomolar potency in the in vitro enzyme inhibition assay (IC(50) = 18 nM) and submicromolar inhibitory activity in a KDR-induced MAP kinase autophosphorylation assay in HUVEC cells (IC(50) = 280 nM), and also demonstrated good in vitro selectivity against a panel of growth factor receptor tyrosine kinases. Further, 14d showed antiangiogenic activity in an aortic ring explant assay by blocking endothelial outgrowths in rat aortas with an IC(50) of 1 microM.

Co-expression of vascular endothelial growth factor C (VEGF-C) and c-erbB2 in human breast carcinoma

Vascular endothelial growth factor C (VEGF-C) has angiogenic and lymphangiogenic properties and is associated with the development of lymphatic metastases in a number of epithelial malignancies. The aim of this study was to determine VEGF-C protein expression in a series of breast carcinomas and correlate this with axillary lymph node (LN) metastases, the presence of lympho-vascular invasion (LVI), bone marrow micro-metastases (BMM) and other clinico-pathological data including oestrogen receptor (ER) and c-erbB2 status. VEGF-C expression was determined by immunohistochemistry (IHC) in 51 tumours. ER and c-erbB2 were also assessed by IHC. Bone marrow analysis was performed using a combination of immunomagnetic separation and immunocytochemistry. Overall, 30/51 (59%) of the tumours were positive for VEGF-C. There was no significant correlation between VEGF-C expression and LN status, LVI, BMM, tumour size, grade or ER status. However, there was an association between c-erbB2 and VEGF-C expression (P=0.013). The correlation between VEGF-C and c-erbB2 suggests a functional relationship and may, in part, explain the aggressive phenotype associated with c-erbB2-positive tumours.

Relationship between gastric carcinogenesis and angiogenesis

AIM: To study the relationship between gastric carcinogenesis and angiogenesis.

METHODS: Experimental model of gastric precancerous lesions and carcinomas was established in rats by chemical carcinogen, N-methyl-N?nitro-soguanidine(MNNG). The specimens were collected in groups at different time points from pre-malignant precursor to gastric carcinoma, the sections were stained by HE and angiogenesis was observed. Tissue sections were also immunohistochemically stained for CD34 antigen, a marker for endothelial cells, and the microvessels were counted.

RESULTS: Only a few microvessels were found in the hyperplastic stage of gastric mucosal glands, but angiogenesis was increased markedly and heterogeneously distributed in the dysplastic stage, especially in specimens with moderate and severe degree of dysplasia as well as in the intra-mucosal carcinoma. Profuse vascularity in the frontier of tumor invasion and tumor stroma was found in the infiltrating carcinoma. Comparison of microvessel counts in low grade lesions(hyperplasia and mild dysplasia) with microvessel counts in moderate(26.3±9.6 vs 17.1±5.6 P < 0.05) and severe dysplasia lesions(32.5±11.7 vs 17.1±5.6 P < 0.01) showed a statistically significant increase in the more advanced lesions, but there was no significant difference in vessel count between moderate and severe degree of dysplasia.

CONCLUSION: Angiogenesis is switched on at the early stage of gastric carcinogenesis, and becomes more pronounced with the progress toward more advanced stage. There is a close relationship between gastric carcinogenesis and angiogenesis.

Optical imaging of cancer metastasis to bone marrow: a mouse model of minimal residual disease

The development of novel anti-cancer strategies requires more sensitive and less invasive methods to detect and monitor in vivo minimal residual disease in cancer models. Bone marrow metastases are indirectly detected by radiography as osteolytic and/or osteosclerotic lesions. Marrow micrometastases elude radiographic detection and, therefore, more sensitive methods are needed for their direct identification. Injection of cancer cells into the left cardiac ventricle of mice closely mimics micrometastatic spread. When luciferase-transfected cells are used, whole-body bioluminescent reporter imaging can detect microscopic bone marrow metastases of approximately 0.5 mm(3) volume, a size below the limit in which tumors need to induce angiogenesis for further growth. This sensitivity translates into early detection of intramedullary tumor growth, preceding the appearance of a radiologically evident osteolysis by approximately 2 weeks. Bioluminescent reporter imaging also enables continuous monitoring in the same animal of growth kinetics for each metastatic site and guides end-point analyses specifically to the bones affected by metastatic growth. This model will accelerate the understanding of the molecular events in metastasis and the evaluation of novel therapies aiming at repressing initial stages of metastatic growth.

Antiangiogenesis therapy. Current and future agents

Approaches to cancer therapy for most tumors in adults and children have changed little in 50 years: surgery, radiation, and chemotherapy are standard for many solid tumors. When the concept of angiogenesis in cancer biology was introduced in the 1970s, there was little recognition of the therapeutic potential of attacking a tumor's blood supply. Advances in understanding the molecular processes that regulate tumor blood supply and novel agents that can interfere with them have generated a great deal of scientific interest and excitement. This article reviews the current understanding of angiogenesis and its role in cancer then discusses new therapeutic options in animals and humans, with a focus on pediatric tumors and the potential for treating them.

Orthotopic transplantation model of human gastrointestinal cancer and detection of micrometastases

AIM: To establish a relevant animal model of human gastrointestinal cancer, which can be used for repetitive investigations, so as to improve our understanding and management of carcinogenesis and cancer metastasis.

METHODS: Intact tissues of human colorectal and pancreatic cancers were transplanted in nude mice. The biological characteristics of the original and the corresponding transplanted tumors were investigated by HE staining, PAS staining and immunostaining. The metastases in the livers and lungs of nude mice were investigated by immunostaining with biotinylated mab KL-1 and by RT-PCR using CK20 specific primers.

RESULTS: There were totally 9 of 16 surgical specimens growing in nude mice subcutaneously and/or orthotopically (4 of 6 colorectal and 5 of 10 pancreatic cancer). Tumor cell content of the specimens and freezing of tissue specimens are important factors influencing the growth of transplanted tumor. In the group of fresh tumor tissues with greater than 50% tumor cell content, the success rate of the transplantation was 100% (3 cases of pancreatic cancer and 3 cases of colorectal cancer). The orthotopically transplanted tumors resemble the original tumor morphologically and biologically, including TAA expression such as CEA by immunohistochemistry, and CEA level in the serum of mice. Ki-67 labeling index and the expression of TAA especially K-ras, 17-1A and RA-96, are associated with the potential of tumor growth in nude mice. Micrometastases in the lungs and livers of tumor bearing mice can be detected by immunostaining with biotinylated mab KL-1 and CK20-specific RT-PCR.

CONCLUSION: An orthotopic transplantation model for human colon and pancreatic cancer in nude mice has been set up. We have also established sensitive detection methods with CK-immunohistochemistry and CK20-RT-PCR to study xenotransplanted human cancer and its metastatic cancer cells in the liver and lung of nude mice. This study may be helpful in understanding the mechanism of cancer metastasis and in developing new diagnostic methods and therapeutic strategies for metastases including micrometastases.