Alpha smooth muscle actin positive stromal cells in gastric carcinoma

Inflammatory myofibroblastic tumor of the maxillary sinus: A case report

Inflammatory myofibroblastic tumors (IMTs) are one of the most complex and rare neoplasms that have been discovered, with varying behavior in different cases. They mostly arise in the thoracic and abdominal cavity, the lungs, retroperitoneum, and extremities. They can also be detected in the head and neck area. IMTs have no age or gender preference which makes them tougher to anticipate. Head and neck IMTs are benign neoplasms with locally aggressive behavior and a low risk of metastatic spread. They have an unknown etiology, and they resemble malignant lesions radiologically. In this case report, we will review the case of a 40-year-old woman with an unusual IMT in the maxillary sinus that presented as a challenge in diagnosis and management.

Preliminary study of some of the main intratumor stroma components in gastric carcinomas

AIM

The relationship between stromal compartment and tumor behavior in gastric carcinomas is still poorly understood and defined. Therefore, the authors started, with this preliminary study, an analysis of stromal compartment morphology and behavior in tumors arising from gastric mucosa epithelium.

MATERIALS AND METHODS

The study group included 75 patients operated for gastric carcinoma. Five parameters describing tumor morphology and behavior and eight parameters describing tumor stroma (TS) morphology were assessed. Histopathological examination included six serial sections of formalin-fixed, paraffin-embedded tumor tissue samples, stained with three classical stains and three antibodies to reveal the different parameters. For data comparison, Pearson's correlation test and the chi-squared (χ²) correlation test were used.

RESULTS

Studied tumors were, usually, infiltrating, undifferentiated∕diffuse type, invasive in subserous spaces and with a Ki67 index higher than 20%. Collagen fibers dominated the stromal components, with a predominance of mature type and an average fibrillary index of 2.7. The whole amount of stromal components accounted for around one quarter of the tumor area. Mature collagen fibers were in opposite correlation with their immature counterpart, and both were in opposite correlation with smooth muscle fibers and expressed an opposite trend of correlation with components of vascular compartment. The whole amount of stromal components had divergent behavior with the components of vascular compartment. The latter expressed generally an opposite trend of correlation with individual fibrillary stromal components. We found only isolated relationships statistically significant between stromal components and tumor characteristics.

CONCLUSIONS

TS is in a continuous remodeling process in relation to the evolution of tumor parenchyma, tumors less differentiated proving to have an immature stroma, with newly formed collagen fibers and higher vascular density. Further studies are required.

Myofibroblast stroma differentiation in infiltrative basal cell carcinoma is accompanied by regulatory T-cells

INTRODUCTION

The implications of infiltrative compared to non-infiltrative growth of cutaneous basal cell carcinoma (BCC) on the tumor stroma and immune cell landscape are unknown. This is of clinical importance, because infiltrative BCCs, in contrast to other BCC subtypes, are more likely to relapse after surgery and radiotherapy.

MATERIALS AND METHODS

This descriptive cross-sectional study analyzed 38 BCCs collected from 2018 to 2021. In the first cohort (n = 28), immune cells were characterized by immunohistochemistry and multiplex immunofluorescence staining for CD3, CD8, CD68, Foxp3, and α-SMA protein expression. In the second cohort (n = 10) with matched characteristics (age, sex, location, and BCC subtype), inflammatory parameters, including TGF-β1, TGF-β2, ACTA2, IL-10, IL-12A, and Foxp3, were quantified via RT-qPCR after isolating mRNA from BCC tissue samples and perilesional skin.

RESULTS

Infiltrative BCCs showed significantly increased levels of α-SMA expression in fibroblasts (p = 0.0001) and higher levels of Foxp3+ (p = 0.0023) and CD3+ (p = 0.0443) T-cells compared to non-infiltrative BCCs. CD3+ (p = 0.0171) and regulatory T-cells (p = 0.0026) were significantly increased in α-SMA-positive tumor stroma, whereas CD8+ T-cells (p = 0.1329) and CD68+ myeloid cells (p = 0.2337) were not affected. TGF-β1 and TGF-β2 correlated significantly with ACTA2/α-SMA mRNA expression (p = 0.020, p = 0.005).

CONCLUSION

Infiltrative growth of BCCs shows a myofibroblastic stroma differentiation and is accompanied by an immunosuppressive tumor microenvironment.

Defining invasion in breast cancer: the role of basement membrane

Basement membrane (BM) is an amorphous, sheet-like structure separating the epithelium from the stroma. BM is characterised by a complex structure comprising collagenous and non-collagenous proteoglycans and glycoproteins. In the breast, the thickness, density and composition of the BM around the ductal lobular system vary during differing development stages. In pathological conditions, the BM provides a physical barrier that separates proliferating intraductal epithelial cells from the surrounding stroma, and its absence or breach in malignant lesions is a hallmark of invasion and metastases. Currently, diagnostic services often use special stains and immunohistochemistry (IHC) to identify the BM in order to distinguish in situ from invasive lesions. However, distinguishing BM on stained sections, and differentiating the native BM from the reactive capsule or BM-like material surrounding some invasive malignant breast tumours is challenging. Although diagnostic use of the BM is being replaced by myoepithelial cell IHC markers, BM is considered by many to be a useful marker to distinguish in situ from invasive lesions in ambiguous cases. In this review, the structure, function and biological and clinical significance of the BM are discussed in relation to the various breast lesions with emphasis on how to distinguish the native BM from alternative pathological tissue mimicking its histology.

Presence/Absence and Specific Location of Resident CD34+ Stromal Cells/Telocytes Condition Stromal Cell Development in Repair and Tumors

CD34+ stromal cells/telocytes (CD34+SCs/TCs) can have a role as mesenchymal precursor cells. Our objective is to assess whether the myofibroblastic stromal cell response in repair and in desmoplastic reactions in tumors depend on the presence or absence of resident CD34+SCs/TCs in specific regions/layers of an organ and on the location of their possible subpopulations. For this purpose, using conventional and immunohistochemical procedures, we studied specimens of (a) acute cholecystitis, with early repair phenomena (n: 6), (b) surgically resected segments of colon tattooed with India ink during previous endoscopic removal of malignant polyps, with macrophage infiltration and stromal cell reaction (n: 8) and (c) infiltrative adenocarcinomas of colon, with desmoplastic reaction (n: 8). The results demonstrated (a) stromal myofibroblastic reaction during repair and tumor desmoplasia in most regions in which resident CD34+SCs/TCs are present, (b) absence of stromal myofibroblastic reaction during repair in the mucosa of both organs in which resident CD34+SCs/TCs are absent and (c) permanence of CD34+SCs/TCs as such, without myofibroblastic response, in smooth muscle fascicles, nerves, and Meissner and Auerbach plexuses, in which the CD34+SCs/TCs mainly undergo reactive phenomena. Therefore, the development of activated αSMA+ myofibroblasts in these conditions requires the presence of resident CD34+SCs/TCs and depends on their location. In conclusion, the facts support the hypotheses that CD34+SCs/TCs participate in the origin of myofibroblasts during repair and tumor stroma formation, and that there is a heterogeneous population of resident CD34+SCs/TCs with different roles.

Immunohistochemical Expression of Epithelial-Mesenchymal Transition Markers in Early Gastric Cancer: Cancer Tissue versus Noncancer Tissue

Background/Aims

Epithelial-mesenchymal transition (EMT) is a developmental process, wherein the epithelial cells show reduced intercellular adhesions and acquire migratory fibroblastic properties. EMT is associated with downregulation in epithelial marker expression, abnormal translocation of E-cadherin, and upregulation in mesenchymal marker expression. Here, we investigated the immunohistochemical (IHC) expression of EMT markers in early gastric cancer (EGC) between cancer and noncancer tissues.

Methods

Tissue samples were prospectively obtained from 19 patients with EGC that underwent endoscopic submucosal dissection (ESD). We compared the expression level of transforming growth factor (TGF)-β, vascular endothelial growth factor (VEGF), E-cadherin, α-smooth muscle actin (α-SMA), and vimentin between cancer and noncancer tissues using IHC. Among the 19 patients, 15 patients had follow-up biopsy at 3 months after ESD for EGC.

Results

Cancer tissues presented higher values of EMT mesenchymal markers (α-SMA/vimentin/TGF-β/VEGF) than the noncancerous tissues (p<0.05) that were significantly low after ESD (p<0.05). No significant correlation was reported for tumor location and initial Helicobacter pylori infection.

Conclusions

The mesenchymal expression of EMT markers was higher in the cancerous tissues than in the noncancer tissues.

Immunohistochemical Expression of Myofibroblasts Using Alpha-smooth Muscle Actin (SMA) to Assess the Aggressive Potential of Various Clinical Subtypes of Ameloblastoma

Objective:

Ameloblastoma is a rare odontogenic neoplasm with high recurrence rates if improperly treated. If left untreated (or is treated inadequately), it can cause substantial morbidity, disfigurement, and even death. Hence, there is a need to explore the stromal cells too, which might play an important role in assessing its aggressive behavior and may help to predict the recurrence of different clinical variants of ameloblastoma. Myofibroblasts (MFs) are such cells which have been studied in various lesions.

Materials and Methods:

This retrospective study involved archival tissues of ameloblastoma. Among a total of 40 cases, 12 cases of SMA (solid multicystic ameloblastoma), 10 cases of unicystic ameloblastoma (UA), 8 cases of desmoplastic ameloblastoma, and 10 cases of oral squamous cell carcinoma were selected as control. Immunohistochemical staining with anti-alpha-smooth muscle actin antibody was done. Interpretation of ten examined fields was counted by three observers.

Results:

Significant difference in the number of MFs in SMA and UA and desmoplastic ameloblastoma and UA (P < 0.05) was found. However, there was no statistically significant difference in MFs of SMA and desmoplastic ameloblastomas (P > 0.05). In addition, there was no statistically significant difference in the staining intensity between the three variants (P > 0.05).

Conclusion:

A significant correlation was obtained between the number of MF in all the three clinical variants, i.e., SMA, UA, and desmoplastic ameloblastoma (P = 0.02), which is the unique feature of the study.

Behaviour of telocytes during physiopathological activation

We consider CD34+ stromal cells/telocytes (CD34+ SC/TCs) in normal and pathological conditions. These cells are involved in organisation and control of the extracellular matrix, structural support, creation of microenvironments, intercellular communication, neurotransmission, immunomodulation and immunosurveillance, inhibition of apoptosis, and control, regulation and source of other cell types. CD34+ SC/TCs are widely reported in the origin of interstitial cells of Cajal and in regeneration in the heart, skeletal muscle, skin, respiratory tree, liver, urinary system and the eye. In addition, we contribute CD34+ SC/TC hyperplasia associated with several processes, including neurogenous hyperplasia (neuroma of the appendix), hyperplasia of Leydig cells in undescended testes (Cryptorchidism), peripheral areas of inflammatory/repair processes (pericicatricial tissue and transitional zones between diseased segments in Crohn's disease and normal bowel), benign tumours (neurofibromas, Antoni-B zones of neurilemmomas, granular cell tumours, and melanocytic nevi) and in some lesions with myxoid, oedematous and degenerative changes (Reinke's oedema, myxomatous mitral valve degeneration, thyroid-associated ophthalmopathy and basophilic degenerative changes of the collagen in the dermis). We pay particular attention to the role of CD34+ SC/TCs during repair through granulation tissue, including morphologic changes, loss of CD34 expression and gain of αSMA expression with myofibroblast transformation, and interactions with pericytes, endothelial and inflammatory cells. Finally, we consider CD34 or αSMA expression in stromal cells of malignant epithelial tumours, and the role of CD34+ SC/TCs in the origin of carcinoma-associated fibroblasts (CAFs) and myofibroblasts. In conclusion, CD34+ SC/TCs play an important role in the maintenance and modulation of tissue homeostasis and in morphogenesis/renewal/repair.

Chemotherapy activates cancer-associated fibroblasts to maintain colorectal cancer-initiating cells by IL-17A

Chemotherapy stimulates cancer-associated fibroblasts to secrete interleukin-17A to provide maintenance cues to support the growth of colorectal cancer-initiating cells.

Many solid cancers display cellular hierarchies with self-renewing, tumorigenic stemlike cells, or cancer-initiating cells (CICs) at the apex. Whereas CICs often exhibit relative resistance to conventional cancer therapies, they also receive critical maintenance cues from supportive stromal elements that also respond to cytotoxic therapies. To interrogate the interplay between chemotherapy and CICs, we investigated cellular heterogeneity in human colorectal cancers. Colorectal CICs were resistant to conventional chemotherapy in cell-autonomous assays, but CIC chemoresistance was also increased by cancer-associated fibroblasts (CAFs). Comparative analysis of matched colorectal cancer specimens from patients before and after cytotoxic treatment revealed a significant increase in CAFs. Chemotherapy-treated human CAFs promoted CIC self-renewal and in vivo tumor growth associated with increased secretion of specific cytokines and chemokines, including interleukin-17A (IL-17A). Exogenous IL-17A increased CIC self-renewal and invasion, and targeting IL-17A signaling impaired CIC growth. Notably, IL-17A was overexpressed by colorectal CAFs in response to chemotherapy with expression validated directly in patient-derived specimens without culture. These data suggest that chemotherapy induces remodeling of the tumor microenvironment to support the tumor cellular hierarchy through secreted factors. Incorporating simultaneous disruption of CIC mechanisms and interplay with the tumor microenvironment could optimize therapeutic targeting of cancer.

NHE1 activity contributes to migration and is necessary for proliferation of human gastric myofibroblasts

Myofibroblasts play central roles in wound healing, deposition of the extracellular matrix and epithelial function. Their functions depend on migration and proliferation within the subepithelial matrix, which results in accelerated cellular metabolism. Upregulated metabolic pathways generate protons which need to be excreted to maintain intracellular pH (pH(i)). We isolated human gastric myofibroblasts (HGMs) from surgical specimens of five patients. Then we characterized, for the first time, the expression and functional activities of the Na(+)/H(+) exchanger (NHE) isoforms 1, 2 and 3, and the functional activities of the Na(+)/HCO(3)(-) cotransporter (NBC) and the anion exchanger (AE) in cultured HGMs using microfluorimetry, immunocytochemistry, reverse transcription polymerase chain reaction and immunoblot analysis. We showed that NHE1-3, NBC and AE activities are present in HGMs and that NHE1 is the most active of the NHEs. In scratch wound assays we also demonstrated (using the selective NHE inhibitor HOE-642) that carbachol and insulin like growth factor II (IGF-II) partly stimulate migration of HGMs in a NHE1-dependent manner. EdU incorporation assays revealed that IGF-II induces proliferation of HGMs which is inhibited by HOE-642. The results indicate that NHE1 is necessary for IGF-II-induced proliferation response of HGMs. Overall, we have characterized the pH(i) regulatory mechanisms of HGMs. In addition, we demonstrated that NHE1 activity contributes to both IGF-II- and carbachol-stimulated migration and that it is obligatory for IGF-II-induced proliferation of HGMs.

Microvessel Density Is Associated with VEGF and α-SMA Expression in Different Regions of Human Gastrointestinal Carcinomas

Tumor angiogenesis is known to be regulated by growth factors secreted by host and tumor cells. Despite the importance of tumor vasculature and angiogenic heterogeneity in solid tumors, few studies have compared the vasculature in different regions of human cancer. Blood vessels from different regions of carcinomas might have morphofunctional implications in tumor angiogenesis. In the present study, therefore, we have examined the relationship between microvascular density (MVD) and vascular endothelial growth factor (VEGF) expression and alpha smooth muscle actin (α-SMA) expression in the center of the tumor (CT), periphery (P) and metastasis (M) regions from gastrointestinal carcinomas (GITC), as well as the association of MVD with clinicopathological factors. Surgically resected specimens corresponding to the CT, P and M from 27 patients were examined for FVIII, VEGF and α-SMA by immunohistochemistry. The MVD was not significantly different in the CT, P and M regions from GITC. The MVD in the VEGF positive group was significantly higher than in the VEGF negative group (CT, p = 0.034; P, p = 0.030; M, p = 0.032). The MVD as a function of α-SMA expression was also significantly higher in the CT and P region compared to the M region (p = 0.0008). In conclusion, the MVD association with VEGF and α-SMA expression, might indicate an increase of the number of neoformed and preexisting blood vessels uniformly or partially covered by pericytes in different regions of GITC, suggesting that not only MVD and VEGF are important parameters to the tumor vasculature, but also blood vessels maturation is a crucial factor for gastrointestinal tumor angiogenesis regulation and possible target of vascular therapy.

Myofibroblasts are associated with the progression of scirrhous gastric carcinoma

Fibroblasts, particularly myofibroblasts, affect the malignant progression of cancer cells in vitro. However, to date few reports have addressed the clinical significance of myofibroblasts in the gastric cancer microenvironment. This study examined the correlation between myofibroblast expression and clinicopathological features in gastric carcinoma. A total of 265 primary gastric tumors resected by gastrectomy were stained with antibodies against α-smooth muscle actin and vimentin. Stromal cells positive for vimentin were considered to be fibroblasts. Myofibroblasts were defined as fibroblasts positive for α-smooth muscle staining. Myofibroblast-positive gastric carcinoma was established when myofibroblasts accounted for more than 25% of fibroblasts in the cancer stroma. Myofibroblast expression was positive in 92 (35%) of the 265 gastric carcinomas. Myofibroblast expression showed a significantly (p<0.001) high frequency in advanced gastric cancers (76 of 146), in comparison to the early stage cancers (16 of 119). Taken together, there was a statistically significant correlation between myofibroblast expression and scirrhous type gastric cancer (p<0.001), lymph node metastasis (p<0.001), lymphatic invasion (p<0.001) and peritoneal dissemination (p=0.005). The prognosis of patients with tumors positive for myofibroblast expression was significantly (p<0.001) worse, while a multivariate analysis revealed that myofibroblast expression was not an independent prognostic factor. These findings suggest that myofibroblasts are associated with scirrhous gastric cancer. Overexpression of myofibroblasts may therefore be a useful prognostic indicator of gastric carcinoma.

Impaired gastric gland differentiation in Peutz-Jeghers syndrome

Gastrointestinal hamartomatous polyps in the Peutz-Jeghers cancer predisposition syndrome and its mouse model (Lkb1(+/-)) are presumed to contain all cell types native to the site of their occurrence. This study aimed to explore the pathogenesis of Peutz-Jeghers syndrome polyposis by characterizing cell types and differentiation of the epithelium of gastric polyps and predisposed mucosa. Both antral and fundic polyps were characterized by a deficit of pepsinogen C-expressing differentiated gland cells (antral gland, mucopeptic, and chief cells); in large fundic polyps, parietal cells were also absent. Gland cell loss was associated with an increase in precursor neck cells, an expansion of the proliferative zone, and an increase in smooth muscle alpha-actin expressing myofibroblasts in the polyp stroma. Lack of pepsinogen C-positive gland cells identified incipient polyps, and even the unaffected mucosa of young predisposed mice displayed an increase in pepsinogen C negative glands (25%; P = 0045). In addition, in small intestinal polyps, gland cell differentiation was defective, with the absence of Paneth cells. There were no signs of metaplastic differentiation in any of the tissues studied, and both the gastric and small intestinal defects were seen in Lkb1(+/-) mice, as well as polyps from patients with Peutz-Jeghers syndrome. These results identify impaired epithelial differentiation as the earliest pathological sign likely to contribute to tumorigenesis in individuals with inherited Lkb1 mutations.

Global hypomethylation of genomic DNA in cancer-associated myofibroblasts

Global hypomethylation has long been recognized as a feature of the malignant epithelial component in human carcinomas. Here we show evidence for this same type of epigenetic alteration in cancer-associated stromal myofibroblasts. We used methylation-sensitive SNP array analysis (MSNP) to profile DNA methylation in early-passage cultures of stromal myofibroblasts isolated from human gastric cancers. The MSNP data indicated widespread hypomethylation in these cells, with rare focal gains of methylation, conclusions that were independently validated by bisulfite sequencing and by a methylation-sensitive cytosine incorporation assay. Immunohistochemistry with anti-5-methylcytosine (anti-5-methyl-C) in a series of gastrectomy specimens showed frequent loss of methylation in nuclei of both the malignant epithelial cells and alpha-smooth muscle actin (ASMA)-positive stromal myofibroblasts of both intestinal-type and diffuse carcinomas. We confirmed this phenomenon and established its onset at the stage of noninvasive dysplastic lesions by immunohistochemistry for anti-5-methyl-C in a transgenic mouse model of multistage gastric carcinogenesis. These findings indicate similar general classes of epigenetic alterations in carcinoma cells and their accompanying reactive stromal cells and add to accumulating evidence for biological differences between normal and cancer-associated myofibroblasts.

Stromal fibroblasts activated by tumor cells promote angiogenesis in mouse gastric cancer

Myofibroblasts, also known as activated fibroblasts, constitute an important niche for tumor development through the promotion of angiogenesis. However, the mechanism of stromal fibroblast activation in tumor tissues has not been fully understood. A gastric cancer mouse model (Gan mice) was recently constructed by simultaneous activation of prostaglandin (PG) E2 and Wnt signaling in the gastric mucosa. Because both the PGE2 and Wnt pathways play a role in human gastric tumorigenesis, the Gan mouse model therefore recapitulates the molecular etiology of human gastric cancer. Microvessel density increased significantly in Gan mouse tumors. Moreover, the expression of vascular endothelial growth factor A (VEGFA) was predominantly induced in the stromal cells of gastric tumors. Immunohistochemistry suggested that VEGFA-expressing cells in the stroma were alpha-smooth muscle actin-positive myofibroblasts. Bone marrow transplantation experiments indicated that a subset of gastric myofibroblasts is derived from bone marrow. Importantly, the alpha-smooth muscle actin index in cultured fibroblasts increased significantly when stimulated with the conditioned medium of Gan mouse tumor cells, indicating that gastric tumor cells activate stromal fibroblasts. Furthermore, conditioned medium of Gan mouse tumor cells induced VEGFA expression both in embryonic and gastric fibroblasts, which further accelerated the tube formation of human umbilical vein endothelial cells in vitro. Notably, stimulation of fibroblasts with PGE2 and/or Wnt1 did not induce VEGFA expression, thus suggesting that factors secondarily induced by PGE2 and Wnt signaling in the tumor cells are responsible for activation of stromal fibroblasts. Such tumor cell-derived factors may therefore be an effective target for chemoprevention against gastric cancer.

Gastric carcinosarcoma with neuroendocrine differentiation as the carcinoma component and leiomyosarcomatous and myofibroblastic differentiation as the sarcomatous component

Gastric carcinosarcoma with neuroendocrine differentiation is a very rare neoplasm. In this article we present such a case. The gastroendoscopic examination of a 59-year-old Japanese man disclosed gastric cancer during follow-up after operation for rectal cancer. Subsequently, total gastrectomy was carried out because of gastric cancer. A large tumor measuring 9.2 x 8.4 cm was observed in the posterior wall of the upper portion of the stomach. The tumor was composed of carcinoma and sarcomatous cells, and the histological transition of both components was observed. Immunohistochemically, carcinoma and sarcomatous cells were positive for cytokeratin CAM5.2. The carcinoma contained adenocarcinoma and malignant cells with neuroendocrine differentiation. The sarcomatous component showed leiomyosarcomatous and myofibroblastic differentiation. The present tumor is the fifth case of gastric carcinosarcoma with neuroendocrine differentiation and the first case of gastric carcinosarcoma with myofibroblastic differentiation. Pathologists should bear in mind that gastric carcinosarcoma may show various types of differentiation.

Non-vascular smooth muscle cells in the human choroid: distribution, development and further characterization

To characterize further non-vascular smooth muscle cells (NVSMC) in the choroid of the human eye, extensive morphological studies were performed including a three-dimensional distribution of NVSMC in the adult human eye and their appearance during development. Whole mounts and sections through the choroid and sclera of eyes of 42 human donors (between the 13th week of gestation and 89 years of age) were stained with antibodies against smooth muscle actin and other markers for smooth muscle cells. On the basis of their morphological localization, three groups of NVSMC could be distinguished in the adult eyes: (a) a semicircular arrangement of NVSMC in the suprachoroid and inner sclera, around the entry of posterior ciliary arteries and nerves; (b) NVSMC parallel to the vessels in the posterior eye segment between the point of entry of the posterior ciliary arteries and the point of exit of the vortex veins; and (c) a dense plaque-like arrangement of NVSMC in the suprachoroid, overlying the foveal region. The last of these groups showed most pronounced interindividual differences. During development, the first NVSMC to be observed at the 20th week of gestation belonged to group b. A complete NVSMC network was first observed in a 6-year-old donor eye. All three groups stained positive for smoothelin, caldesmon and calponin in all localizations. The NVSMC show a distinct distribution that might reflect different aspects of their function in the choroid and suprachoroid. All cells could be histochemically characterized as truly contractile.

Coordinate cell-surface expression of matrix metalloproteinases and their inhibitors on cancer-associated myofibroblasts from malignant ascites in patients with gastric carcinoma

PURPOSE

The crucial role of tumor stroma in cancer cell invasion has been described in human carcinoma tissues. However, myofibroblastic invasion remains largely unexplored in malignant ascites. Purpose of this study is to investigate the spatial localization or regulation of matrix metalloproteinases (MMP-2, -7 -9, MT1-MMP) and their inhibitors (TIMP-2 and -4) on myofibroblasts from malignant ascites in 20 patients with gastric carcinoma.

METHODS

The quantitative flow cytometric analysis of MMPs or TIMPs on myofibroblasts was based on the percentage of double positive cells defined by anti MMPs or anti TIMPs, and anti alpha-smooth muscle actin (alpha-SMA) antibodies.

RESULT

The results clearly showed that the coordination of the high level of cell-surface expression of secreted MMPs and TIMPs was noted on the alpha-SMA+ myofibroblasts. The finding suggests the possible formation of ternary complex, MT1-MMP/TIMPs/MMPs on the cells. The events might be a cause and result of activation processing of MMPs on the cells.

CONCLUSION

This study provides the presence of invasive myofibroblasts with activated MMPs in close association with MMPs+ and TIMPs+ cancer cells and tumor-infiltrating lymphocytes from malignant ascites, emphasizing the importance of molecular cross-talk in tumor-host microenvironment for cancer invasion, metastasis and progression.

Pericryptal fibroblast sheath in intestinal metaplasia and gastric carcinoma

BACKGROUND AND AIMS

In the progression of chronic gastritis, gastric mucosal cells deviate from the normal pathway of gastric differentiation to an intestinal phenotype which is closely related to gastric carcinoma. However, to date, it has not been elucidated whether the intestinal metaplasia is merely a change in the epithelium or whether the underlying mesenchyme also changes from gastric type to intestinal type. We have investigated the relationship between intestinal metaplasia and the pericryptal fibroblast sheath (PCFS) in the mesenchyme. In addition, we also examined PCFS in gastric carcinoma.

METHODS

We determined the existence of PCFS in the intestinal metaplastic mucosa and carcinoma of both human and Cdx2 transgenic mouse stomach. PCFS was determined using the antibody against alpha-smooth muscle actin and electron microscopic observations.

RESULTS

PCFS formed an almost complete layer around the small and large intestinal crypts while it did not exist around the normal gastric glands in both mice and humans. PCFS was seen around the glands of intestinal metaplastic mucosa in both Cdx2 transgenic mouse and human stomachs. However, PCFS was virtually absent in the intestinal-type gastric adenocarcinoma area.

CONCLUSION

We successfully demonstrated that the epithelium as well as the mesenchyme changed from the gastric type to the intestinal type in intestinal metaplasia and that PCFS disappeared in intestinal-type gastric carcinoma.

Presence of vascular adventitial fibroblastic cells in diffuse-type gastric carcinomas

AIM

To investigate morphological changes in the tumour vessel adventitia, particularly the distribution of vascular adventitial fibroblastic cells (VAFCs)--namely, CD34 positive fibroblastic cells just outside the vascular media--in diffuse-type gastric carcinomas.

METHOD

In total, 18 surgically resected advanced typical diffuse-type gastric carcinomas and their normal tissues were examined. Immunostaining for CD34, CD31, high molecular weight caldesmon (HCD), and cytokeratin 8 (CAM5.2) was performed to detect VAFCs. VAFCs are positive for CD34 but negative for CD31, and are located just outside the vascular media (HCD positive vascular smooth muscle bundle). The areas just outside the vascular media in the whole maximum tumour cut surface were assessed, except the tumour growing edge, which was confirmed by immunostaining with CAM5.2. CD34 positive and CD31 negative cells just outside the vascular media were defined as VAFCs.

RESULTS

VAFC containing vessels were seen in 17 of the 18 diffuse carcinoma tissues. Vessels lacking VAFCs were also detected in these 17 tumours. In contrast, all of the vessels lacked VAFCs in the remaining tumour. In the 18 samples of normal tissue, all of the vessels contained VAFCs.

CONCLUSIONS

These results suggest that the presence of VAFCs is associated with the infiltration of diffuse scattered gastric carcinoma cells.

Lack of vascular adventitial fibroblastic cells in tumour stroma of intestinal-type and solid-type gastric carcinomas

AIMS

To investigate the roles of vascular adventitial fibroblastic cells in tumour stroma, the distribution of vascular adventitial fibroblastic cells was studied in gastric carcinomas.

METHODS

In total, 50 surgically resected gastric carcinomas (43 intestinal type, and seven solid type) and their normal tissues were examined. Vascular adventitial fibroblastic cells are positive for CD34 but negative for CD31. To differentiate vascular adventitial fibroblastic cells from vascular endothelial cells, immunostaining for CD34 and CD31 was performed. Immunostaining for high molecular weight caldesmon was also performed to recognise vascular media.

RESULTS

In normal gastric tissues, CD34 positive fibroblastic cells were found just outside the vascular media, namely vascular adventitial fibroblastic cells. In contrast, all of the 43 intestinal-type and seven solid-type gastric carcinomas had no vascular adventitial fibroblastic cells in the tumour stroma.

CONCLUSIONS

These results suggest that a lack of vascular adventitial fibroblastic cells is associated with tumour stroma formation in intestinal-type and solid-type gastric carcinomas.