Characteristics of cis-Diamminedichloroplatinum-selected In Vitro Passaged Cells Derived from a Transplantable Rat Malignant Fibrous Histiocytoma

A cis -iamminedichloroplatinum (CDDP)-selected cell line (MT-R10) was induced by continuous exposure of an in vitro passaged cell line (MT-P) established from a transplantable rat malignant fibrous histiocytoma (MFH-MT) to CDDP. MT-R10, capable of proliferating in the presence of l.0 μg CDDP/ml, was passaged in CDDP free medium. The doubling time of MT-R10 at passage 10 (MT -R10/10) was almost the same as that of MT -P, being 22.3 and 25.5 h, respectively. The concentration of CDDP required for 50% inhibition of MT-R10/10 proliferation was two-fold higher than that of MT-P. MT-R10 consisted of round, epithelial-type cells arranged in compact sheets. Ultrastructurally, MT-R10 had numerous free ribosomes, some mitochondria, and other poorly developed cytoplasmic or-ganelles suggesting its undifferentiated nature. MT -R10 showed no reaction for acid phosphatase or non-specific esterase. Tumors induced in syngeneic rats by inoculation with MT-R10 consisted of small, round, undifferentiated cells with scanty cytoplasm. They showed organoid and trabecular patterns, and were often arranged in compact sheets. The neoplastic cells showed no reaction for any of the histiocytic lysosomal and antigenic markers tested, but exhibited a strong reaction for alkaline phosphatase. Bone formation was often observed in the tumors. These observations suggest that CDDP selected, undifferentiated cells may have osteogenic potential and may be one of the progenitor cells of MFH-MT.     

Potential osteogenic differentiation of cisplatin-resistant rat malignant fibrous histiocytoma-derived cell lines.

Histological modulations in tumor cells treated with anti-cancer drugs have been reported. The histogenesis of malignant fibrous histiocytoma (MFH) remains elusive. To investigate cellular characteristics and alterations, therefore, we derived cisplatin-resistant MFH cell lines (MT-PR and MT-10R) from MT-P and MT-10, respectively, and compared them with MT-10, a non-cisplatin-resistant MFH line (MT-10 was isolated as a clone cell line from MT-P, and MT-P was originally established from a rat spontaneous MFH). Immunohistochemically, MT-10 reacted to vimentin, alpha-smooth muscle actin (a marker of myofibroblasts), ED1/ED2 (rat macrophage/histiocyte-specific antibodies), and A3 (rat MFH-specific antibody) in varying degrees, indicating that MFH cells have features of both fibroblasts and histiocytes. However, MT-10R and MT-PR reduced ED1-positive cell numbers. MT-10 developed tumors of a storiform pattern, while MT-10R and MT-PR tumors comprise round or polygonal cells arranged in a compact sheet. Additionally, MT-PR tumors included ossifying areas. MT-10R and MT-PR, and their tumors showed a reaction to alkaline phosphatase (ALP), a marker of osteoblasts. RT-PCR revealed that mRNAs of bone morphogenetic protein (BMP)-2, BMP-6 and osteopontin were significantly increased in MT-10R and MT-PR tumors. Neoplastic cells in these tumors were immunoreactive to BMP-2 and BMP-6, while MT-10 tumors were not. Cisplatin-resistant MFH cells had potential to differentiate into osteogenic tissues by producing osteogenic factors, suggesting that MFH histology may be altered under anti-cancer drug treatments. Recently, cancer differentiation-based therapy, that could be induced by anti-cancer drugs, has been implied. MT-10R and MT-PR become useful experimental systems for studies on cellular differentiation provoked by anti-cancer drugs.     

Phenotypic modulation in cisplatin-resistant cloned cells derived from transplantable rat malignant fibrous histiocytoma

The histogenesis of malignant fibrous hlstlocytoma (MFH) was studled using clsplatln (CDDP)-resistant MT-R8 and MT-R9 cells derlved from cloned undlfferentiated MT-8 and flbrohlstlocytic MT-9 cells, resoecthfely, which had been established from transplantable rat MFH. CDDP concentrations requlred for 50% suppression of prollferation of MT-R8 and MT-R9 cells were 5.4– and 3.3-fold greater than those of parental MT-8 and MT-9, respectively. MT-R8 and MT-Rg showed the higher positive rates to histimytic lysosomal/ antigenic (ED1 and ED2) markers. The number of a-smoath muscle actin (SMA)-positive cells significantly Increased in MT-RB; SMA-positlve cells were also obsenred in MT-R9, but no difference was seen between MT-9 and MT-R9. MT-R8 and MT-R9 expressed both histiwytic and myofibroblastic phenotypes. However, the histology of subcutaneous tumors induced in syngeneic rats by MT-R8 and MR-R9 did not always reflect their in vitro nature. MT-R8 developed undiffer-entlated sarcomas similar to parental MT-8 tumors. In contrast, MT-R9 induced tumors with polytypic histologies such as the storiform growth pattern, neoplastlc growth of granular cells and myofibroblasts, osteosarcoma-like areas, collagen-rich areas containing well-developed fibroblasts and areas involvlng many lipoblasts. These In vivo observatfons suggest the multidlrectional differentiation of MT-R9 cells. Phenotypic modulation of rat MFH cells seemed to be easily induced by CDDP. A possible histogenesis of MFH was discussed based on the data collected.     

Tumour lines from a spontaneous rat endometrial stromal sarcoma, showing dendritic cell-like and myofibroblastic cell-like phenotypes

A transplantable tumour (RY) and cell lines (RY-PB and clone RY-B-E3 isolated from RY-PB) were established from a naturally occurring endometrial stromal sarcoma (ESS) found in a 24-month-old female F344 rat. The primary tumour and RY tumours, which had been serially passaged in syngeneic female rats up to the 10th generation, consisted of spindle or round cells arranged in ill-defined bundles or sheets. Neoplastic cells of the primary and RY tumours, as well as cultured cells of RY-PB and RY-B-E3, showed positive reactions to vimentin, ED1/ED2 (both for rat macrophages/histiocytes), OX6 (for dendritic cells expressing rat MHC class II antigens), and lysosomal enzymes such as acid phosphatase and non-specific esterase, in varying degrees. Ultrastructurally, neoplastic cells characteristically had tubulovesicular system-like structures and variously developed lysosomes in the cytoplasm. Neoplastic cells also exhibited immunoexpression to an alpha-smooth muscle actin (alpha-SMA). The addition of transforming growth factor (TGF)-beta1 to RY-PB and RY-B-E3 cultures increased the number of alpha-SMA-positive cells, whilst the positive cell number was decreased by anti-TGF-beta antibody. The RT-PCR method revealed the expression of TGF-beta1 mRNA in the cultured cells. The present study showed that rat ESS-derived cells exhibited dendritic cell-like and myofibroblastic cell-like phenotypes. The histogenesis of ESSs in human beings and rats remains poorly understood, and these tumour lines may therefore become useful tools for further research.     

Spontaneous Cerebellar Primitive Neuroectodermal Tumor in a Juvenile Cynomolgus Monkey (Macaca fascicularis)

A neoplastic mass compressing the left cerebellar hemisphere and hindbrain was observed at trimming in a 3½-year-old male cynomolgus monkey from a control dose group. Microscopically, the neoplastic mass was nonencapsulated, invasive, and showed two morphological patterns. The predominant area consisted of densely packed undifferentiated, polygonal to spindle cells arranged in vague sheets supported by a scant fibrovascular stroma. The other area was less cellular and composed of round neoplastic cells separated by eosinophilic fibrillar material. Immunohistochemical staining for vimentin, synaptophysin, glial fibrillary acidic protein, neuron-specific enolase, neurofilament, and S-100 confirmed the presence of primitive undifferentiated neuroectodermal cells and some cells with neuronal or glial differentiation. On the basis of histopathology and immunohistochemical findings, a diagnosis of cerebellar primitive neuroectodermal tumor with neuronal and glial differentiation was made. Primitive neuroectodermal tumors are rare in animals including nonhuman primates; this is the first published report in this species.     

Development of spindle-shaped cells and chondroid cells from androgen-dependent Shionogi carcinoma 115. A light and electron microscopic study

Androgen-dependent Shionogi carcinoma 115 (SC115) is an undifferentiated medullary carcinoma consisting of compact round cells. However, when host male DS mice were castrated 2 weeks after tumor transplantation, tumors composed of compact round cells, spindle-shaped cells and chondroid cells grew 4 weeks after castration. Compact round cells with desmosomes were arranged in solid nests and exhibited immunoreactivity for keratin protein. Spindle-shaped cells had prominent rough endoplasmic reticulum, and appeared to secrete collagen. Chondroid cells had the characteristics of chondrocytes. The light and electron microscopic features were highly suggestive of a transition from compact round cells to spindle-shaped cells, and from spindle-shaped cells to chondroid cells. The histology of this tumor thus suggests that SC115 cells are able to change into chondroid cells via spindle-shaped cells.     

DEVELOPMENT OF SPINDLE-SHAPED CELLS AND CHONDROID CELLS FROM ANDROGEN-DEPENDENT SHIONOGI CARCINOMA 115: A Light and Electron Microscopic Study

Androgen-dependent Shionogi carcinoma 115 (SC115) is an undifferentiated medullary carcinoma consisting of compact round cells. However, when host male DS mice were castrated 2 weeks after tumor transplantation, tumors composed of compact round cells, spindle-shaped cells and chondroid cells grew 4 weeks after castration. Compact round cells with desmosomes were arranged in solid nests and exhibited immunoreactivity for keratin protein. Spindle-shaped cells had prominent rough endoplasmic reticulum, and appeared to secrete collagen. Chondroid cells had the characteristics of chon-drocytes. The light and electron microscopic features were highly suggestive of a transition from compact round cells to spindle-shaped cells, and from spindle-shaped cells to chondroid cells. The histology of this tumor thus suggests that SC115 cells are able to change into chondroid cells via spindle-shaped cells. ACTA PATHOL JPN 38: 1405–1416, 1988.     

In vitro osteogenic differentiation of rat bone marrow cells subcultured with and without dexamethasone

The aim of our study was to investigate the osteogenic potential of subcultured rat bone marrow cells. Rat bone marrow (RBM) cells were cultured with or without dexamethasone. Subsequently, osteogenic differentiation and expression was studied. When cells were cultured continuously in the presence of dexamethasone, cultures initially showed high alkaline phosphatase expression and abundant mineralization. Expression of differentiation markers decreased with passaging. After cells were passaged three times, no alkaline phosphatase activity and calcification were found. Primary cells cultured without dexamethasone showed low alkaline phosphatase and no calcification, and remained fibroblast-like. When these cells were subcultured in the presence of dexamethasone, the cells did show osteogenic differentiation. Nevertheless, this occurred at a significant lower level than with cells continuously cultured with dexamethasone. In addition, no differentiation was found after second passage. Our results indicate that subcultured undifferentiated RBM cells show osteogenic differentiation after addition of dexamethasone. Expression of alkaline phosphatase and mineralization is higher in cells continuously supplemented with dexamethasone. Still, even when dexamethasone is added continuously, RBM cells loose their osteogenic potential after several passages. Therefore, we conclude that subculture of undifferentiated rat bone marrow cells results in the loss of osteogenic potential of these cells.     

Histopathological and immunohistochemical study of neuroendocrine tumors of the rectum

A clinicopathological and immunohistochemical study was carried out on 32 cases of neuroendocrine tumors of the rectum. Typical carcinoids consisted of 27 cases, histologically showing uniform round to columnar cells forming solid alveolar nests and ribbon-like or trabecular arrangement. Neuroendocrine carcinomas consisted of 5 cases in which tumor cells with prominent nuclear atypism were arranged in a ribbon-like or trabecular fashion and formed gland-like structures. There were also small round tumor cells resembling lymphocytes. The prognosis of neuroendocrine carcinomas is very poor with marked tumor invasion of lymphatics and veins resulting in liver metastases and death within one year after operation. Thirty cases out of the 32 showed a positive argyrophil reaction, while immunohistochemistry of 29 cases revealed more than one peptide hormone in 23 cases. The most common hormone was somatostatin being present in 18 of the 23 tumors and glucagon in 16 of the 23 tumors. Gastrin/CCK and calcitonin were proven in 6 of the 23 tumors and in 4 of the 23 tumors, respectively. On the other hand, more than two hormones was present in 15 of the 23 tumors examined. Histologically, neuroendocrine tumors have a very wide spectrum. Histogenetically, typical carcinoids and neuroendocrine carcinomas are considered to be of the same origin with the former showing morphological and functional differentiation to endocrine cells and the latter being more undifferentiated.     

Peripheral primitive neuroectodermal tumor of the small bowel mesentery: a case showing perforation at onset

A case of peripheral primitive neuroectodermal tumor of the small bowel mesentery with an uncommon clinical onset is reported. A 40-year-old man was admitted to hospital because of acute severe abdominal pain. Chest X-ray revealed a free air sign beneath the diaphragm. At emergency surgery a mass measuring 11.0 x 8.0 cm with perforation was located in the jejunal mesenteric region. Histologically the resected lesion consisted of sheets of undifferentiated small round cells forming abortive Homer Wright rosettes. Some spindle-shaped cells showed perivascular pseudorosettes. Immunohistochemical study revealed that the tumor cells expressed positivity against CD99 (MIC2), neuron-specific enolase, synaptophysin and vimentin. To the authors' knowledge this is the first documentation of peripheral primitive neuroectodermal tumor of the small bowel mesentery with perforation at onset.     

EXTRASKELETAL EWING'S SARCOMA

This clinicopathologic study concerns 8 cases of extraskeletal Ewing's sarcoma, including electron-microscopic examination of one case. In three patients, autopsy was done. The age of the patients ranged from 12 to 31 years with a median of 16 years. The tumors mainly arose in the soft tissues of the trunk (4 cases) and the lower extremity (3 cases). Histologically, they were made up of closely packed uniform, small cells, arranged in sheets separated by strands of fibrovascular stroma. The tumor cells had round to oval nuclei with finely dispersed chromatin and scanty ill-defined cytoplasm almost invariably containing a fair amount of diastase-digested PAS-positive material. Ultra-structurally, the tumor cells were composed principally of undifferentiated mesenchymal cells, and contained prominent pools of glycogen in the cytoplasm. Aggregates of intermediate filaments were seen in a perinuclear location. These light- and electron-microscopic findings are indistinguishable from those of Ewing's sarcoma of the bone. Differential points from other soft-tissue small round cell sarcomas such as malignant neuroepithelioma (peripheral neuroblastoma), embryonal or alveolar rhabdomyosarcoma were briefly discussed.     

Extraskeletal Ewing's sarcoma. A clinicopathologic and electron microscopic. Analysis of 8 cases

This clinicopathologic study concerns 8 cases of extraskeletal Ewing's sarcoma, including electron-microscopic examination of one case. In three patients, autopsy was done. The age of the patients ranged from 12 to 31 years with a median of 16 years. The tumors mainly arose in the soft tissues of the trunk (4 cases) and the lower extremity (3 cases). Histologically, they were made up of closely packed uniform, small cells, arranged in sheets separated by strands of fibrovascular stroma. The tumor cells had round to oval nuclei with finely dispersed chromatin and scanty ill-defined cytoplasm almost invariably containing a fair amount of diastase-digested PAS-positive material. Ultrastructurally, the tumor cells were composed principally of undifferentiated mesenchymal cells, and contained prominent pools of glycogen in the cytoplasm. Aggregates of intermediate filaments were seen in a perinuclear location. These light- and electron-microscopic findings are indistinguishable from those of Ewing's sarcoma of the bone. Differential points from other soft-tissue small round cell sarcomas such as malignant neuroepithelioma (peripheral neuroblastoma), embryonal or alveolar rhabdomyosarcoma were briefly discussed.     

SO-CALLED SCLEROSING HEMANGIOMA OF THE LUNG

Sclerosing hemangioma of the lung (SHL) was investigated immunohistochemlcally, histochemically and ultrastructurally with reference to cellular components associated with the histologic pattern: cuboidal cells in the papillary type, round cells in the solid type, flat cells in the hemorrhagic type and stromal cells in the sclerotic type. immunohistochemically, cuboidal cells were positive for CEA, cytokeratin and EMA, whereas other cells were positive for EMA and vimentin. immunoreactive factor-VIII-related antigen was confined to endothelial cells. Histochemically, cuboidal cells displayed alkaline phosphatase activity, but round cells showed ATPase activity. However, in spite of these different histochemical and immunohistochemical properties, morphological continuity was clearly revealed in immunostained sections; direct connection of spaces lined by cuboidal and fiat cells, direct contact between cuboidal and stromal cells, and EMA expression of round cells associated with luminal structures were evident Ultrastructurally, cuboidal cells were like alveolar cells. Flat and stromal cells showed microvillous protrusions and a discontinuous basement membrane, but some cells contained lamellar bodies. Solid cellular sheets consisted of various cells intermediate between cuboidal and flat or stromal cells. Direct apposition among these cells was evident This morphological continuum confirms that each of these cell types are components of SHL as a whole. SHL may thus be merely sclerotic hemorrhagic alveolar cell tumor.     

So-called sclerosing hemangioma of the lung. An immunohistochemical, histochemical and ultrastructural study

Sclerosing hemangioma of the lung (SHL) was investigated immunohistochemically, histochemically and ultrastructurally with reference to cellular components associated with the histologic pattern: cuboidal cells in the papillary type, round cells in the solid type, flat cells in the hemorrhagic type and stromal cells in the sclerotic type. Immunohistochemically, cuboidal cells were positive for CEA, cytokeratin and EMA, whereas other cells were positive for EMA and vimentin. Immunoreactive factor-VIII-related antigen was confined to endothelial cells. Histochemically, cuboidal cells displayed alkaline phosphatase activity, but round cells showed ATPase activity. However, in spite of these different histochemical and immunohistochemical properties, morphological continuity was clearly revealed in immunostained sections; direct connection of spaces lined by cuboidal and flat cells, direct contact between cuboidal and stromal cells, and EMA expression of round cells associated with luminal structures were evident. Ultrastructurally, cuboidal cells were like alveolar cells. Flat and stromal cells showed microvillous protrusions and a discontinuous basement membrane, but some cells contained lamellar bodies. Solid cellular sheets consisted of various cells intermediate between cuboidal and flat or stromal cells. Direct apposition among these cells was evident. This morphological continuum confirms that each of these cell types are components of SHL as a whole. SHL may thus be merely sclerotic hemorrhagic alveolar cell tumor.     

Small Cell Undifferentiated Carcinoma of the Uterine Cervix: Histology, Ultrastructure, and Immunohistochemistry of Two Cases

Two clinical stage IB small cell undifferentiated carcinomas (SCUC) of the cervix were studied by light and electron microscopy and immunohistochemistry. Both cases occurred in women aged less than 31 years. Despite radical hysterectomy and external pelvic radiotherapy, both patients died of recurrent disease within 14 months after initial therapy. The tumors consisted of sheets of closely packed, uniform small, round to oval cells with hyperchromatic nuclei and scant indistinct cytoplasm. One case was associated with cervical squamous cell carcinoma. The neoplastic cells had few organelles and desmosome-like junctions and lacked mucinous or neurosecretory granules or tonofilaments. Immunohistochemistry failed to reveal S-100, CEA, neuropeptides or neuron-specific enolase.

SCUC probably arises either from basal cells of the cervical squamous epithelium, or gland cells of the endocervical epithelium, or still from subcolumnar endocervical reserve cells. Based on ultrastructure and immunohistochemistry, SCUC seems to represent the undifferentiated variant of small cell neuroendocrine tumors of the cervix.     

Epithelioid leiomyoma of the larynx

We describe the pathological features of a case of laryngeal epithelioid leiomyoma (leiomyoblastoma) which, to our knowledge, is the second case to be reported in the world literature. A review of the literature confirmed that leiomyoma as such is a very rare neoplasm in the larynx, and only 33 cases have been previously reported. The neoplasm was located in the left vocal cord and consisted of mainly epithelioid, round or spindle-shaped cells, often with clear cytoplasm, which were arranged predominantly in solid nests and sheets. The tumour cells showed positive immunoreactivity for smooth muscle actin and desmin. The tumour showed low mitotic activity and immunostaining with MIB 1 (Ki-67) accordingly revealed the occasional cell only to be positive, confirming a low proliferative activity in agreement with a benign neoplasm. Epithelioid leiomyomas located in other sites have been shown to act occasionally in a malignant fashion, and the necessity for careful long-term follow-up of the patient is therefore emphasized.     

Influence of the site of tumor growth on the capacity of a low tumorigenic line of Friend erythroleukemia cells to differentiate.

Friend erythroleukemia cells (FLC) passaged in mice are highly tumorigenic and multiply extensively in the livers of suckling DBA/2 mice without differentiating. In contrast, in vitro passaged FLCs injected intravenously were of low tumorigenicity, multiplied to a limited extent in the livers of suckling mice, and underwent marked differentiation from the proerythroblast to the orthochromatic erythroblast stage in the liver. The presence of characteristic C-type virions budding from the cell surface in various stages of erythroid differentiation served as a marker of the injected FLCs. When the same in vitro passaged FLCs that differentiated in the liver were injected subcutaneously in suckling mice, they formed large subcutaneous tumors consisting of sheets of undifferentiated tumor cells. It is concluded that the tumorigenicity of FLCs depended on the site of tumor growth and that there is an inverse correlation between the tumorigenic capacity and the capacity to differentiate.     

Morphological characteristics of a transplantable nephroblastoma (NB-Y) in F344 rats and the relation of tumour growth to hyper-reninaemia in NB-Y-bearing rats.

A transplantable tumour, designated NB-Y, was established from a spontaneous nephroblastoma in an F344 rat. NB-Y was serially passaged in syngeneic rats by subcutaneous implantation up to the 49th generation. The transplants grew into nodules with an average diameter of 5 cm and average weight of 92.9 g 4 weeks after implantation. The primary tumour and NB-Y consisted mainly of sheets or clusters of undifferentiated blastemal cells, which reacted immunohistochemically for vimentin but not for keratin. Renin-containing cells were observed in the small blood vessel walls within the primary tumour, but neoplastic cells of both primary tumour and NB-Y failed to stain for renin. Plasma renin activity was significantly higher (40.7 ng per ml per h) in transplanted rats 4 weeks after implantation compared with non-transplanted controls (28.0 ng per ml per h). Hyperplastic juxtaglomerular cells were often observed in rats bearing NB-Y. Sinusoidal dilatation was present in the liver, adrenal glands, pituitary gland and bone marrow of recipients, suggesting abnormal blood flow provoked via the renin-angiotensin system. The present study revealed the development of hyper-reninaemia in NB-Y-bearing rats, but its pathogenesis remains unknown.     

Undifferentiated round cell sarcomas with novel SS18‐POU5F1 fusions

Despite significant recent advances in characterizing the molecular pathogenesis of undifferentiated round cell neoplasms, rare cases remain unclassified. Here, we report two distinctive undifferentiated round cell tumors occurring in young adults. One tumor presented intrabdominally and the other arose within the abdominal wall. One patient died of disease following local and distance recurrence, despite aggressive chemotherapy and radiotherapy. Morphologically, both tumors were similarly composed of primitive round to epithelioid cells arranged in nests, sheets, and trabecular patterns. The cytoplasm was scant and amphophilic, while the nuclei were round and uniform with brisk mitotic activity. Focal necrosis was present. Immunohistochemically, both tumors were variably positive for S100 and EMA, and one case focally expressed cytokeratin and TLE1. Targeted RNA sequencing revealed in both an identical SS18‐POU5F1 fusion gene. Fluorescence in situ hybridization was performed which confirmed SS18 and POU5F1 gene rearrangements. Expression data, relative to over 200 other mesenchymal neoplasms that had undergone targeted RNA sequencing on the same platform, suggested the SS18‐POU5F1 tumors cluster with EWSR1/FUS‐POU5F1‐positive myoepithelial tumors. In view of our limited sample size, additional studies are needed to characterize the breadth of clinical and pathologic findings in these neoplasms. In addition, further investigation is necessary to determine whether this entity represents a clinically aggressive and phenotypically undifferentiated variant of myoepithelial tumors, or perhaps an altogether novel category of undifferentiated round cell sarcoma.