Overlapping morphological, immunohistochemical and genetic features of superficial CD34-positive fibroblastic tumor and PRDM10-rearranged soft tissue tumor

Superficial CD34-positive fibroblastic tumor (SCD34FT) is a recently recognized soft tissue tumor that is considered to be of borderline malignancy. The pathogenesis of this tumor remains incompletely understood, but it has been suggested that SCD34FT overlaps with tumors showing fusions involving the PRDM10 gene. Previous analyses of PRDM10-rearranged tumors have demonstrated that they have a distinct gene expression profile, resulting in high expression of CADM3 (also known as SynCam3), which can be detected immunohistochemically. Here, we investigated a series (n = 43) of SCD34FT or PRDM10-rearranged tumors and potential mimics (n = 226) with regard to morphological, genetic, and immunohistochemical features. The results show that SCD34FT and PRDM10-rearranged tumor are morphologically indistinguishable; 41 of 43 tumors of both entities are CADM3-positive. Hence, we suggest that they constitute a single entity, preferably referred to as SCD34FT. Expression of CADM3 was only rarely seen in other soft tissue tumors, except in tumors with Schwann cell differentiation. Thus, IHC for CADM3, in combination with the characteristic morphological features, is a valuable adjunct in the diagnosis of SCD34FT.

Genomic and transcriptomic characterization of desmoplastic small round cell tumors

Desmoplastic small round cell tumor (DSRCT) is a highly aggressive soft tissue tumor primarily affecting children and young adults. Most cases display a pathognomonic EWSR1-WT1 gene fusion, presumably constituting the primary driver event. Little is, however, known about secondary genetic changes that may affect tumor progression. We here studied 25 samples from 19 DSRCT patients using single nucleotide polymorphism arrays and found that all samples had copy number alterations. The most common imbalances were gain of chromosomes/chromosome arms 1/1q and 5/5p and loss of 6/6q and 16/16q, all occurring in at least eight of the patients. Five cases showed homozygous deletions, affecting a variety of known tumor suppressor genes, for example, CDKN2A and NF1. As almost all patients died of their disease, the impact of individual imbalances on survival could not be evaluated. Global gene expression analysis using mRNA sequencing on fresh-frozen samples from seven patients revealed a distinct transcriptomic profile, with enrichment of genes involved in neural differentiation. Two genes - GJB2 and GAL - that showed higher expression in DSRCT compared to control tumors could be further investigated for their potential as diagnostic markers at the protein level.

Early endoscopic assessment after esophagectomy can predict anastomotic complications: a novel scoring system

BACKGROUND

Anastomotic leakage after esophagectomy is a serious and demanding complication. Early detection and treatment can probably prevent clinical deterioration of the patient. We have used early endoscopic assessment and a novel endoscopy score to predict anastomotic complications.

METHODS

57 patients planned for Ivor Lewis esophagectomy were included. Endoscopy videos were recorded and biopsies were taken from the gastric conduit on day 7 or 8 after esophagectomy. A scoring system based on the endoscopic appearance, the combined endoscopy score (0-6), was developed. Scoring of the videos was done blinded. Patient outcome with regards to anastomotic complications was registered on postoperative day 30 in accordance with the ECCG definitions and compared to histopathology assessment and the combined endoscopy score retrospectively.

RESULTS

The rate of anastomotic defect (necrosis and leakage, ECCG definitions) was 19%. 7 out of 8 patients with a combined endoscopy score of ≥ 4 developed anastomotic defects. The combined endoscopy score was the only predictor for anastomotic complications.

CONCLUSION

Prediction of anastomotic complications enables early detection and treatment which often limits the clinical extent of the complication. Early postoperative endoscopy is safe and a relatively simple procedure. The combined endoscopy score is an accurate tool to predict anastomotic complications.

PRDM10-rearranged Soft Tissue Tumor: A Clinicopathologic Study of 9 Cases

Gene fusion transcripts containing PRDM10 were recently identified in low-grade undifferentiated pleomorphic sarcomas (UPS). Here, we describe the morphologic and clinical features of 9 such tumors from 5 men and 4 women (age: 20 to 61 y). Three cases had previously been diagnosed as UPS, 3 as superficial CD34-positive fibroblastic tumor (SCD34FT), 2 as pleomorphic liposarcoma, and 1 as pleomorphic hyalinizing angiectatic tumor. The tumors were located in the superficial and deep soft tissues of the thigh/knee region (4 cases), shoulder (2 cases), foot, trunk, and perineum (1 case each) ranging in size from 1 to 6 cm. All showed poorly defined cellular fascicles of pleomorphic cells within a fibrous stroma with frequent myxoid change and a prominent inflammatory infiltrate. All displayed highly pleomorphic nuclear features, but a low mitotic count. Most tumors were well circumscribed. One of 9 tumors recurred locally, but none metastasized. Immunohistochemically, all were CD34 and showed nuclear positivity for PRDM10; focal positivity for cytokeratins was seen in 5/6 cases. PRDM10 immunoreactivity was evaluated in 50 soft tissue tumors that could mimic PRDM10-rearranged tumors, including 4 cases exhibiting histologic features within the spectrum of SCD34FT. Except for 2/6 pleomorphic liposarcomas and 1/4 myxofibrosarcomas, other tumors did not show nuclear positivity but displayed weak to moderate cytoplasmic immunoreactivity. In conclusion, PRDM10-rearranged soft tissue tumor is characterized by pleomorphic morphology and a low mitotic count. Its morphologic spectrum overlaps with SCD34FT. Clinical features of this small series suggest an indolent behavior, justifying its distinction from UPS and other sarcomas.

Intraoperative liver steatosis characterization using diffuse reflectance spectroscopy

BACKGROUND

Liver steatosis is associated with poor outcome after liver transplantation and liver resection. There is a need for an accurate and reliable intraoperative tool to identify and quantify steatosis. This study aimed to investigate whether surface diffuse reflectance spectroscopy (DRS) measurements could detect liver steatosis on humans during liver surgery.

METHODS

The DRS instrumentation setup consists of a computer, a high-power tungsten halogen light source and two spectrometers, connected through a trifurcated optical fiber to a hand-held probe. Patients scheduled for open resection for liver tumors were considered for inclusion. Multiple DRS measurements were performed on the liver surface after mobilization.

RESULTS

In total, 1210 DRS spectra originated from 38 patients, were analyzed. When applying the data to an analytical model the volumetric absorption ratio factor of fat and water specified an explicit distinction between mild to moderate, and moderate to severe steatosis (p < 0.001). There were significant differences between none-to-mild and moderate-to-severe steatosis grade for the following parameters: reduced scattering coefficient (p < 0.001), Mie to total scattering fraction (p < 0.001), Mie slope (p = 0.003), lipid/(lipid + water) (p < 0.001), blood volume (p = 0.044) and bile volume (p < 0.001).

CONCLUSION

This study shows that it is possible to evaluate steatosis grades with hepatic surface diffuse reflectance spectroscopy measurements.

Different patterns of clonal evolution among different sarcoma subtypes followed for up to 25 years

To compare clonal evolution in tumors arising through different mechanisms, we selected three types of sarcoma-amplicon-driven well-differentiated liposarcoma (WDLS), gene fusion-driven myxoid liposarcoma (MLS), and sarcomas with complex genomes (CXS)-and assessed the dynamics of chromosome and nucleotide level mutations by cytogenetics, SNP array analysis and whole-exome sequencing. Here we show that the extensive single-cell variation in WDLS has minor impact on clonal key amplicons in chromosome 12. In addition, only a few of the single nucleotide variants in WDLS were present in more than one lesion, suggesting that such mutations are of little significance in tumor development. MLS displays few mutations other than the FUS-DDIT3 fusion, and the primary tumor is genetically sometimes much more complex than its relapses, whereas CXS in general shows a gradual increase of both nucleotide- and chromosome-level mutations, similar to what has been described in carcinomas.

Loss of the tumour suppressor gene AIP mediates the browning of human brown fat tumours

Human brown fat tumours (hibernomas) show concomitant loss of the tumour suppressor genes MEN1 and AIP. We hypothesized that the brown fat phenotype is attributable to these mutations. Accordingly, in this study, we demonstrate that silencing of AIP in human brown preadipocytic and white fat cell lines results in the induction of the brown fat marker UCP1. In human adipocytic tumours, loss of MEN1 was found both in white (one of 51 lipomas) and in brown fat tumours. In contrast, concurrent loss of AIP was always accompanied by a brown fat morphology. We conclude that this white-to-brown phenotype switch in brown fat tumours is mediated by the loss of AIP. Copyright © 2017 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.

Preoperative Aspartate Aminotransferase-to-Platelet Ratio Index Predicts Perioperative Liver-Related Complications Following Liver Resection for Colorectal Cancer Metastases

BACKGROUND AND AIMS

There are limited data on the potential role of preoperative non-invasive markers, specifically the aspartate-to-alanine aminotransferase ratio and the aspartate aminotransferase-to-platelet ratio index, in predicting perioperative liver-related complications after hepatectomy for colorectal cancer metastases.

METHODS

Patients undergoing liver resection for colorectal cancer metastases in a European institution during 2003-2010 were retrospectively enrolled. Relevant data, such as neoadjuvant chemotherapy, preoperative liver function tests, and perioperative complications, were collected from medical records. The nontumorous liver parenchyma in the surgical specimens of 31 patients was re-evaluated.

RESULTS

Overall, 215 patients were included. In total, 40% underwent neoadjuvant chemotherapy and 47% major resection, while 47% had perioperative complications (6% liver-related). In multivariate regression analysis, the aspartate aminotransferase-to-platelet ratio index was independently associated with liver-related complications (odds ratio: 1.149, p = 0.003) and perioperative liver failure (odds ratio: 1.155, p = 0.012). The latter was also true in the subcohort of patients with neoadjuvant chemotherapy (odds ratio: 1.157, p = 0.004) but not in those without such therapy (p = 0.062). The aspartate-to-alanine aminotransferase ratio was not related to liver-related complications (p = 0.929). The area under the receiver operating characteristics curve for the aspartate aminotransferase-to-platelet ratio index as a predictor of liver-related complications was 0.857 (p = 0.008) in patients with neoadjuvant chemotherapy. Increasing aspartate aminotransferase-to-platelet ratio index was observed with an increase in degrees of sinusoidal obstruction syndrome (p = 0.01) but not for fibrosis (p = 0.175) or steatosis (p = 0.173) in the nontumorous liver in surgical specimens.

CONCLUSION

The preoperative aspartate aminotransferase-to-platelet ratio index, but not the aspartate-to-alanine aminotransferase ratio, predicts perioperative liver-related complications following hepatectomy due to colorectal cancer metastases, in particular after neoadjuvant chemotherapy. The aspartate aminotransferase-to-platelet ratio index is related to sinusoidal obstruction syndrome in the nontumorous liver.

Frequent low-level mutations of protein kinase D2 in angiolipoma

Tumours displaying differentiation towards normal fat constitute the most common subgroup of soft tissue neoplasms. A series of such tumours was investigated by whole-exome sequencing followed by targeted ultra-deep sequencing. Eighty per cent of angiolipomas, but not any other tumour type, displayed mutations in the protein kinase D2 (PRKD2) gene, typically in the part encoding the catalytic domain. The absence of other aberrations at the chromosome or RNA level suggests that PRKD2 mutations are critical for angiolipoma development. Consistently, the mutated PRKD2 alleles were present at low (3-15%) frequencies, indicating that only a subset of the tumour cells is affected. Indeed, by sequencing mature fat cells and other cells separately, the former typically showed the highest mutation frequencies. Thus, we hypothesize that altered PRKD2 signalling in the adipocytic cells drives tumourigenesis and, in agreement with its pivotal role in angiogenesis, induces the vessel formation that is characteristic for angiolipoma. Copyright © 2016 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.

A New Method for Endoscopic Sampling of Submucosal Tissue in the Gastrointestinal Tract: A Comparison of the Biopsy Forceps and a New Drill Instrument

Background Sampling of submucosal lesions in the gastrointestinal tract through a flexible endoscope is a well-recognized clinical problem. One technique often used is endoscopic ultrasound-guided fine-needle aspiration, but it does not provide solid tissue biopsies with preserved architecture for histopathological evaluation. To obtain solid tissue biopsies from submucosal lesions, we have constructed a new endoscopic biopsy tool and compared it in a crossover study with the standard double cupped forceps. Methods Ten patients with endoscopically verified submucosal lesions were sampled. The endoscopist selected the position for the biopsies and used the instrument selected by randomization. After a biopsy was harvested, the endoscopist chose the next site for a biopsy and again used the instrument picked by randomization. A total of 6 biopsies, 3 with the forceps and 3 with the drill instrument, were collected in every patient. Results The drill instrument resulted in larger total size biopsies (mm²; Mann-Whitney U test, P = .048) and larger submucosal part (%) of the biopsies (Mann-Whitney U test, P = .003) than the forceps. Two patients were observed because of chest pain and suspicion of bleeding in 24 hours. No therapeutic measures were necessary to be taken. Conclusion The new drill instrument for flexible endoscopy can safely deliver submucosal tissue samples from submucosal lesions in the upper gastrointestinal tract.

Adjuvant radiotherapy in retroperitoneal sarcomas. A Scandinavian Sarcoma Group study of 97 patients

BACKGROUND

Currently there is no consensus on the use of adjuvant radiotherapy (RT) in retroperitoneal sarcoma (RPS). We have analysed clinical outcomes in patients with localised RPS treated at two Scandinavian Sarcoma Group (SSG) centres: Haukeland University Hospital (HUH), Bergen, Norway and Skåne University Hospital (SUH), Lund, Sweden to clarify the effects of adjuvant RT on local control and overall survival (OS).

MATERIAL AND METHODS

Local databases and registers at HUH and SUH as well as the SSG central register were used to identify RPS patients. Patients with localised RPS who underwent surgery in Bergen between 1988 and 2009 and in Lund from 1998 to 2009 were included. Medical records were examined for clinical data, tumour characteristics, treatment factors and follow-up status. Archived tumour sections and tumour tissue were reviewed, and when necessary, restained and reclassified. Cox regression was used to analyse the association of potential prognostic factors with local recurrence-free survival (LRFS), metastasis-free survival (MFS) and OS.

RESULTS

The study included 97 patients: 52 from Norway and 45 from Sweden. The proportion of high-grade tumours was 73%. The five-year LRFS, MFS and OS were 55%, 59% and 60%, respectively. RT was significantly associated with improved local control resulting in a five-year LRFS of 77% compared with 39% without (p < 0.001). Furthermore, five-year OS was 71% in the RT group in contrast to 52% with surgery alone (p = 0.019). In the adjusted analysis RT proved to be a significant factor also for MFS (HR = 0.42, 95% CI 0.20-0.88, p = 0.021). In addition, high-grade malignancy, large tumour and positive surgical margin were risk factors for local recurrence. High malignancy grade was the only significant adverse prognostic factor for metastasis. High age and high-grade malignancy were negative prognostic factors for OS.

CONCLUSION

Adjuvant RT was significantly associated with an improved five-year LRFS and OS.

Small soft tissue sarcomas do metastasize: identification of high-risk tumors

BACKGROUND

Small (≤ 5 cm) soft tissue sarcomas (STS) of the extremities and the trunk wall generally have a favorable prognosis. However, 1 of 10 patients do develop metastases, and we therefore aimed to determine predictors of metastasis in a population-based cohort of patients with small STSs.

PATIENTS AND METHODS

In the southern Sweden health care region, 848 adult patients with STS of the extremities or the trunk wall were diagnosed between 1986 and 2010. Of these, 243 STS (29 %) were ≤5 cm. Prognostic evaluation was performed in 229 patients with localized disease at diagnosis, 181 of whom had histologic high-grade tumors.

RESULTS

None of the 48 patients with low-grade tumors developed metastases, whereas 24 of 181 patients with high-grade tumors (13 %) tumors did. Presence of either tumor necrosis or vascular invasion predicted development of metastases with a hazard ratio of 2.9 (95 % CI, 1.0-7.9), and tumors with both factors had a hazard ratio of 12 (95 % CI, 4.1-37) for metastasis (adjusted for size).

CONCLUSIONS

Our population-based series of STSs ≤5 cm demonstrate an overall good prognosis with metastases developing in 13 % of the patients with high-grade tumors. Tumor necrosis and vascular invasion were the major predictors of metastatic disease in this subset. Tumors with both these risk factors metastasized in 8 of 18 patients, which corresponds to a 12-fold increased risk of metastasis. These findings suggest that although small STS generally are linked to a good prognosis, necrosis and vascular invasion are features indicating biologically aggressive tumors for which treatment and surveillance should equal that for larger tumors.

Reduced expression of angiotensin II and angiotensin receptor type 1 and type 2 in resistance arteries from nasal lesions in granulomatosis with polyangiitis (Wegener's granulomatosis)

OBJECTIVES

Angiotensin II (ANGII) is involved in vessel inflammation and is important in the development of cardiovascular disorders such as atherosclerosis. During active disease, patients with granulomatosis with polyangiitis (GPA; Wegener's granulomatosis) have accelerated atherosclerosis and ANGII inhibitors are recommended to these patients to reduce atherosclerosis. We assessed the hypothesis that the expression of ANGII and its receptors in arteries in granulomatous lesions change in GPA.

METHODS

ANGII and angiotensin receptors were quantified in vessels from granulomatous lesions from patients with GPA using immunohistochemistry. Anti- ANGI type 1 (AT1) and type 2 (AT2) antibodies were applied on formalin-fixed and paraffin-embedded biopsies from nasal mucous membranes from eight patients with GPA and eight controls.

RESULTS

ANGII expression was localized to the endothelial cells (ECs) in arteries and sparsely to vascular smooth muscle cells (VSMCs) in nasal biopsies. AT1 receptor (AT1R) staining was intense and located in the VSMCs in the medial layer of the control arteries. AT2 receptor (AT2R) immunostaining was faint and was located only in the ECs. Patients with GPA showed marked down-regulation of positively immunostained ECs for ANGII or AT2R, and a reduced number of AT1R in VSMCs. ANGII, AT1R, and AT2R staining was persistent on infiltrating leucocytes.

CONCLUSIONS

These results suggest down-regulation of the angiotensin system in arteries in granulomatous nasal lesions in GPA. Inhibition of the angiotensin system may prove less efficient in inhibiting the vascular inflammation process in GPA.

Increased angiotensin II type 1 receptor expression in temporal arteries from patients with giant cell arteritis

PURPOSE

Currently, giant cell arteritis (GCA) is primarily treated with corticosteroids or immunomodulating agents, but there is interest in identifying other noncorticosteroid alternatives. Similarities exist in the injury pathways between GCA and atherosclerosis. Angiotensin II is a vasoactive peptide involved in vessel inflammation during atherosclerosis, and angiotensin II receptor inhibitors are effective in preventing atherosclerosis. The present study was performed to elucidate the role of angiotensin type 1 (AT(1)) and type 2 (AT(2)) receptors in GCA.

DESIGN

Experimental retrospective immunohistochemical study of temporal arteries using archival formalin-fixed, paraffin-embedded tissue.

PARTICIPANTS

Ten patients with GCA and 10 control patients, who were clinically suspected of having GCA but were diagnosed as not having GCA, were included.

METHODS

Immunohistochemistry, using anti-AT(1) and anti-AT(2) antibodies, was performed on formalin-fixed and paraffin-embedded temporal arteries.

MAIN OUTCOME MEASURES

AT(1) and AT(2) receptor immunostaining intensity was quantified.

RESULTS

Hematoxylin-eosin-stained sections of temporal arteries from patients with GCA showed intimal hyperplasia, internal elastic lamina degeneration, and band-shaped infiltrates of inflammatory cells, including lymphocytes, histocytes, and multinucleated giant cells. AT(1) receptor staining was primarily observed in the medial layer of the temporal arteries and was higher in the patients with GCA than in the control patients. This was a result of increased AT(1) receptor immunostaining of both vascular smooth muscle cells and infiltrating inflammatory cells. Only faint immunostaining was seen for AT(2) receptors, primarily in the endothelial cells, and to a lesser extent on the smooth muscle cells. Immunostaining with antibodies for the AT(2) receptor was similar in the patients with GCA and in controls.

CONCLUSIONS

These results suggest that AT(1) receptors play a role in the development of GCA. Inhibition of the angiotensin system may thus provide a noncorticosteroid alternative for the treatment of GCA.

FINANCIAL DISCLOSURE(S)

The author(s) have no proprietary or commercial interest in any materials discussed in this article.

Identification of low-risk tumours in histological high-grade soft tissue sarcomas

In more than one-third of patients with a histological high-grade malignant soft tissue sarcoma metastasis develops despite local control of the primary tumour. Hence, adjuvant chemotherapy is increasingly used for these relatively chemoresistant tumours which requires improved prognostication to exclude low-risk patients from overtreatment. We assessed the value of stepwise prognostication in a series of 434 histological high-grade STS of the extremity and trunk wall. Vascular invasion was used as the first discriminator whereafter the risk factors tumour necrosis, size (>8cm) and infiltrating growth pattern were used to discriminate high- and low-risk tumours. We identified a high-risk group with a cumulative incidence of metastasis >0.4 at 5 years, and a low-risk group, comprising half of the tumours, with a cumulative incidence of metastasis <0.15. The model was validated in an independent material of 175 patients. This model improved prognostication in STS and is of value for identifying patients who probably should not receive adjuvant chemotherapy.

Fine-needle aspiration of soft tissue leiomyosarcoma: An analysis of the most common cytologic findings and the value of ancillary techniques

This study aims to determine the diagnostic accuracy of fine-needle aspiration cytology (FNAC) of primary leiomyosarcoma (LMS) of soft tissue and to review diagnostic criteria and adjunctive methods, which can contribute to a confident diagnosis. We evaluated the preoperative FNAC in 89 patients with primary LMS for the following: cytomorphology and correspondence of FNA to histological features of excised tumors and clinical data. In addition, the utility of adjunctive techniques was analyzed and other spindle-cell lesions in the differential diagnoses were discussed. An unequivocal, malignant diagnosis was rendered by FNAC in 78 cases; 74 tumors were diagnosed as sarcoma, of which 31 as LMS or suspicion of LMS. In addition, three smears were labeled as malignant tumor, one as carcinoma metastasis, and three as neurilemmoma. Seven aspirates were inconclusive and one insufficient. On reevaluation, the diagnostic smears in most cases contained tumor cell fascicles with an admixture of dispersed cells or stripped nuclei. The most common cells were spindle cells with elongated, blunt-ended, segmented or fusiform nuclei, and round/polygonal cells, often with rounded or indented nuclei. In addition, 51 cases showed pleomorphic, often multinucleated cells. Osteoclasts, intranuclear vacuoles, and mitoses occurred in 14, 47, and 27 cases, respectively. Thus, most high-grade LMSs have cytologic features that allow diagnosis of sarcoma. Ancillary studies can confirm the diagnosis of LMS and help in the correct interpretation of predominant spindle-cell or epitheloid-cell smears resembling neurilemoma or carcinoma, respectively.

Acute Effects of Liver Vein Occlusion by Stent-Graft Placed in Transjugular Intrahepatic Portosystemic Shunt Channel: An Experimental Study

The purpose of this study was to evaluate the effects of hepatic vein occlusion by stent-graft used in transjugular intrahepatic portosystemic shunt (TIPS). The experiments were performed in six healthy pigs under general anesthesia. Following percutaneous transhepatic implantation of a port-a-cath in the right hepatic vein, TIPS was created with a stent-graft (Viatorr; W L Gore, Flagstaff, AZ, USA). The outflow from the hepatic vein, blocked by the stent-graft was documented by injection of contrast medium and repeated injections of (99)Tc(m)-labeled human serum albumin through the port-a-cath. After 2 weeks, the outflow was re-evaluated, the pigs were sacrificed, and histopathologic examination of the liver was performed. Occlusion of the hepatic vein by a stent-graft had a short and temporary effect on the outflow. Histopathological examination from the affected liver segment showed no divergent pattern. Stent-grafts used in TIPS block the outflow from the liver vein, but do not have a prolonged circulatory effect and do not affect the liver parenchyma.

Adriamycin cytotoxicity may stimulate growth of hepatocellular tumours in an experimental model for adjuvant systemic chemotherapy in liver transplantation

Adjuvant treatment with adriamycin has been suggested to improve results after liver transplantation for hepatocellular cancer. Here we have applied an animal model for evaluation of treatment with adriamycin and/or cyclosporine A on liver tumour growth. Three chemically induced rat liver tumours with various degree of differentiation were transferred to the spleens of syngenic rats. Each recipient group was divided into four subgroups, treated with adriamycin and/or cyclosporine A or none of the drugs. When the tumour was well differentiated no proliferation was found in any of the subgroups. When the tumour exhibited a more pronounced dysplasia, adriamycin stimulated tumour growth. This effect was further increased by cyclosporine. In the animals transplanted with the most aggressive tumour, adriamycin inhibited tumour growth. When given together with cyclosporine this inhibition was counteracted. These data suggest that adriamycin, especially when given together with cyclosporine, may have a stimulatory effect on liver tumour cell growth.

Induced drug resistance inhibits selection of initiated cells and cancer development

Compounds exerting a mitoinhibitory effect on normal hepatocytes are potent promoters in the resistant hepatocyte model of chemical carcinogenesis in combination with stimulation of regenerative growth by partial hepatectomy or treatment with carbon tetrachloride. 2-Acetylaminofluorene (2-AAF) almost completely inhibits liver cell regeneration after partial hepatectomy, allowing only resistant cells to participate in regenerative growth. After initiation by diethylnitrosamine and promotion with 2-AAF and partial hepatectomy (PH), focal growth of initiated cells generates liver lesions which occupy 40% of the hepatic volume three weeks after PH. In this work the mechanism for the anti promoting effects of phenobarbital and 3-methylcholantrene were investigated as well as their effects on the development of malignant hepatocellular carcinoma in the resistant hepatocyte model. Treatment with phenobarbital or, especially, 3-methylcholanthrene rendered normal rat hepatocytes resistant to the mitoinhibitory effect of 2-AAF. In combination with 2-AAF/PH, 3-methylcholanthrene shortened the regenerative growth period to less than one week. In the Solt-Farber protocol for experimental hepatocarcinogenesis, treatment with phenobarbital or 3-methylcholanthrene during promotion with 2-AAF/PH permitted hepatocytes surrounding the focal lesions to respond with regenerative growth. The foci and surrounding liver grew until the liver/body mass index reached the control value. With phenobarbital treatment the total focal volume was 20% of the liver volume three weeks after PH, whereas the corresponding value in the case of 3-methylcholanthrene was only 1%. Labelling index data supported the conclusion that growth of the liver lesions in the resistant hepatocyte model was dependent on differential inhibition of normal hepatocyte growth by the promoter and that the size of the foci obtained was related to the length of time after PH required to complete liver regeneration. 3-methylcholanthrene induced 2-AAF resistance prevented the development of large persistent nodules and hepatocellular carcinoma while phenobarbital delayed cancer development with several month. The data thus supports the idea that the degree of clonal expansion during promotion determines the size of the population at risk for malignant transformation, as well as the final frequency of carcinomas.

Asialoglycoprotein receptors in rat liver nodules

The asialoglycoprotein (ASGP) receptor, binding and internalizing glycoproteins exposing terminal galactose or N-acetylgalactosamine residues, was compared in normal liver, regenerating liver and liver nodules. The total cellular content of ASGP binding sites was reduced to 50 and 40% in regenerating liver and liver nodules respectively, compared to the level in normal liver. The ASGP receptor was heterogeneously distributed in subcellular fractions, with the highest enrichment (16-fold) found in a low-density membrane fraction (LDMF), enriched in endosomes and Golgi complex membranes. The subcellular distribution pattern was similar in the three different liver tissues, except that the relative enrichment in LDMF was less pronounced in regenerating liver (13-fold) and even less in liver nodules (5-fold). Scatchard analysis of the binding data indicated that the receptor populations in all liver tissues were homogeneous with dissociation constants in the range of 0.12-0.47 nM. The difference in ASGP receptor binding activity was not found to be the result of an increased occupancy with endogenous ligand. In vivo endocytosis of [125I]asialo-orosomucoid ([125I]ASOR) showed a reduction in the amount of internalized ligand in liver nodules, well correlated with the reduced number of binding sites compared to normal liver. However, a slower than normal intracellular metabolism of internalized ligand in the nodules was indicated. Bifunctional cross-linking experiments showed [125I]ASOR--receptor complexes of Mr 250,000, 110,000 and 85,000 in normal and regenerating liver, whereas in liver nodules only the Mr 85,000 was seen. It is concluded that ASGP binding activity is reduced in regenerating liver and in liver nodules. This reduction was manifested predominantly in membranes derived from the Golgi complex, in endocytic vesicles and at the cell surface. The slower than normal rate of decay of the internalized ligand in liver nodules is suggested to be the result of alterations in ligand dissociation and receptor recycling processes. Furthermore, the absence of high molecular cross-linkable [125I]ASOR--receptor complexes in liver nodules may reflect an alteration in receptor oligomerization.