Ribosome subunit attrition and activation of the p53-MDM4 axis dominate the response of MLL-rearranged cancer cells to WDR5 WIN site inhibition

The chromatin-associated protein WD Repeat Domain 5 (WDR5) is a promising target for cancer drug discovery, with most efforts blocking an arginine-binding cavity on the protein called the "WIN" site that tethers WDR5 to chromatin. WIN site inhibitors (WINi) are active against multiple cancer cell types in vitro, the most notable of which are those derived from MLL-rearranged (MLLr) leukemias. Peptidomimetic WINi were originally proposed to inhibit MLLr cells via dysregulation of genes connected to hematopoietic stem cell expansion. Our discovery and interrogation of small molecule WIN site inhibitors, however, revealed that they act in MLLr cell lines to suppress ribosome protein gene (RPG) transcription, induce nucleolar stress, and activate p53. Because there is no precedent for an anti-cancer strategy that specifically targets RPG expression, we took an integrated multi-omics approach to further interrogate the mechanism of action of WINi in MLLr cancer cells. We show that WINi induce depletion of the stock of ribosomes, accompanied by a broad yet modest translational choke and changes in alternative mRNA splicing that inactivate the p53 antagonist MDM4. We also show that WINi are synergistic with agents including venetoclax and BET-bromodomain inhibitors. Together, these studies reinforce the concept that WINi are a novel type of ribosome-directed anti-cancer therapy and provide a resource to support their clinical implementation in MLLr leukemias and other malignancies.

Structure-based discovery of potent WD repeat domain 5 inhibitors that demonstrate efficacy and safety in preclinical animal models

WD repeat domain 5 (WDR5) is a core scaffolding component of many multiprotein complexes that perform a variety of critical chromatin-centric processes in the nucleus. WDR5 is a component of the mixed lineage leukemia MLL/SET complex and localizes MYC to chromatin at tumor-critical target genes. As a part of these complexes, WDR5 plays a role in sustaining oncogenesis in a variety of human cancers that are often associated with poor prognoses. Thus, WDR5 has been recognized as an attractive therapeutic target for treating both solid and hematological tumors. Previously, small-molecule inhibitors of the WDR5-interaction (WIN) site and WDR5 degraders have demonstrated robust in vitro cellular efficacy in cancer cell lines and established the therapeutic potential of WDR5. However, these agents have not demonstrated significant in vivo efficacy at pharmacologically relevant doses by oral administration in animal disease models. We have discovered WDR5 WIN-site inhibitors that feature bicyclic heteroaryl P7 units through structure-based design and address the limitations of our previous series of small-molecule inhibitors. Importantly, our lead compounds exhibit enhanced on-target potency, excellent oral pharmacokinetic (PK) profiles, and potent dose-dependent in vivo efficacy in a mouse MV4:11 subcutaneous xenograft model by oral dosing. Furthermore, these in vivo probes show excellent tolerability under a repeated high-dose regimen in rodents to demonstrate the safety of the WDR5 WIN-site inhibition mechanism. Collectively, our results provide strong support for WDR5 WIN-site inhibitors to be utilized as potential anticancer therapeutics.

WIN site inhibition disrupts a subset of WDR5 function

WDR5 nucleates the assembly of histone-modifying complexes and acts outside this context in a range of chromatin-centric processes. WDR5 is also a prominent target for pharmacological inhibition in cancer. Small-molecule degraders of WDR5 have been described, but most drug discovery efforts center on blocking the WIN site of WDR5, an arginine binding cavity that engages MLL/SET enzymes that deposit histone H3 lysine 4 methylation (H3K4me). Therapeutic application of WIN site inhibitors is complicated by the disparate functions of WDR5, but is generally guided by two assumptions-that WIN site inhibitors disable all functions of WDR5, and that changes in H3K4me drive the transcriptional response of cancer cells to WIN site blockade. Here, we test these assumptions by comparing the impact of WIN site inhibition versus WDR5 degradation on H3K4me and transcriptional processes. We show that WIN site inhibition disables only a specific subset of WDR5 activity, and that H3K4me changes induced by WDR5 depletion do not explain accompanying transcriptional responses. These data recast WIN site inhibitors as selective loss-of-function agents, contradict H3K4me as a relevant mechanism of action for WDR5 inhibitors, and indicate distinct clinical applications of WIN site inhibitors and WDR5 degraders.

Displacement of WDR5 from Chromatin by a WIN Site Inhibitor with Picomolar Affinity

The chromatin-associated protein WDR5 is a promising target for pharmacological inhibition in cancer. Drug discovery efforts center on the blockade of the “WIN site” of WDR5, a well-defined pocket that is amenable to small molecule inhibition. Various cancer contexts have been proposed to be targets for WIN site inhibitors, but a lack of understanding of WDR5 target genes and of the primary effects of WIN site inhibitors hampers their utility. Here, by the discovery of potent WIN site inhibitors, we demonstrate that the WIN site links WDR5 to chromatin at a small cohort of loci, including a specific subset of ribosome protein genes. WIN site inhibitors rapidly displace WDR5 from chromatin and decrease the expression of associated genes, causing translational inhibition, nucleolar stress, and p53 induction. Our studies define a mode by which WDR5 engages chromatin and forecast that WIN site blockade could have utility against multiple cancer types.

WDR5 is a chromatin-associated protein and promising anti-cancer target. Aho et al. show that WDR5 controls the expression of ribosome protein genes and describe how small molecule inhibitors of WDR5 displace it from chromatin, causing impeded translation, nucleolar stress, and induction of p53-dependent apoptosis in leukemia cells.

WDR5 is a conserved regulator of protein synthesis gene expression

WDR5 is a highly-conserved nuclear protein that performs multiple scaffolding functions in the context of chromatin. WDR5 is also a promising target for pharmacological inhibition in cancer, with small molecule inhibitors of an arginine-binding pocket of WDR5 (the 'WIN' site) showing efficacy against a range of cancer cell lines in vitro. Efforts to understand WDR5, or establish the mechanism of action of WIN site inhibitors, however, are stymied by its many functions in the nucleus, and a lack of knowledge of the conserved gene networks-if any-that are under its control. Here, we have performed comparative genomic analyses to identify the conserved sites of WDR5 binding to chromatin, and the conserved genes regulated by WDR5, across a diverse panel of cancer cell lines. We show that a specific cohort of protein synthesis genes (PSGs) are invariantly bound by WDR5, demonstrate that the WIN site anchors WDR5 to chromatin at these sites, and establish that PSGs are bona fide, acute, and persistent targets of WIN site blockade. Together, these data reveal that WDR5 plays a predominant transcriptional role in biomass accumulation and provide further evidence that WIN site inhibitors act to repress gene networks linked to protein synthesis homeostasis.

Inhibition of MYC by the SMARCB1 tumor suppressor

SMARCB1 encodes the SNF5 subunit of the SWI/SNF chromatin remodeler. SNF5 also interacts with the oncoprotein transcription factor MYC and is proposed to stimulate MYC activity. The concept that SNF5 is a coactivator for MYC, however, is at odds with its role as a tumor-suppressor, and with observations that loss of SNF5 leads to activation of MYC target genes. Here, we reexamine the relationship between MYC and SNF5 using biochemical and genome-wide approaches. We show that SNF5 inhibits the DNA-binding ability of MYC and impedes target gene recognition by MYC in cells. We further show that MYC regulation by SNF5 is separable from its role in chromatin remodeling, and that reintroduction of SNF5 into SMARCB1-null cells mimics the primary transcriptional effects of MYC inhibition. These observations reveal that SNF5 antagonizes MYC and provide a mechanism to explain how loss of SNF5 can drive malignancy.

Abstract LB-206: Inhibition of MYC by the SMARCB1 tumor suppressor

The SMARCB1 tumor suppressor (SNF5) is a known interaction partner of the oncoprotein c-MYC (MYC), and thought to serve as a co-activator of its transcriptional properties. This role of SNF5, however, is at odds with the tumor suppressor function of SNF5, and with findings that loss of SNF5 is associated with activation of MYC target gene signatures. We have used biochemical, genetic, and genome-wide approaches to reexamine the relationship of SNF5 with MYC within the context of malignant rhabdoid tumor (MRT), an aggressive childhood cancer in which SNF5 is lost. We find that, consistent with activation of MYC target gene signatures in tumors that lack SNF5, MYC function is important for multiple aspects of MRT biology. Surprisingly, SNF5 is capable of inhibiting MYC binding to E boxes in vitro and globally within the context of chromatin. Using ATAC-seq, RNA-seq, and PRO-Seq, we demonstrate that regulation of MYC binding by SNF5 is independent of the role of SNF5 in chromatin remodeling, but instead is responsible for controlling RNA polymerase pause release at MYC-regulated genes. These findings inform a novel model of MRT tumorigenesis in which loss of SNF5 derepresses MYC function, raising the possibility that MYC contributes to disease progression in this malignancy.

Citation Format: April M. Weissmiller, Jing Wang, Shelly L. Lorey, Gregory C. Howard, Ernest Martinez, Qi Liu, William P. Tansey. Inhibition of MYC by the SMARCB1 tumor suppressor [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr LB-206.

Interaction of Gcn4 with target gene chromatin is modulated by proteasome function

The yeast transcription factor Gcn4 requires a ubiquitin ligase and the proteasome in order to function. Inhibiting proteasome function prevents the interaction of Gcn4 with target gene chromatin, and this activity is suppressed by inactivation of the ubiquitin-selective chaperone Cdc48. Thus proteolysis of Gcn4 is not required for its function.

The ubiquitin–proteasome system (UPS) influences gene transcription in multiple ways. One way in which the UPS affects transcription centers on transcriptional activators, the function of which can be stimulated by components of the UPS that also trigger their destruction. Activation of transcription by the yeast activator Gcn4, for example, is attenuated by mutations in the ubiquitin ligase that mediates Gcn4 ubiquitylation or by inhibition of the proteasome, leading to the idea that ubiquitin-mediated proteolysis of Gcn4 is required for its activity. Here we probe the steps in Gcn4 activity that are perturbed by disruption of the UPS. We show that the ubiquitylation machinery and the proteasome control different steps in Gcn4 function and that proteasome activity is required for the ability of Gcn4 to bind to its target genes in the context of chromatin. Curiously, the effect of proteasome inhibition on Gcn4 activity is suppressed by mutations in the ubiquitin-selective chaperone Cdc48, revealing that proteolysis per se is not required for Gcn4 activity. Our data highlight the role of Cdc48 in controlling promoter occupancy by Gcn4 and support a model in which ubiquitylation of activators—not their destruction—is important for function.

Interaction with WDR5 promotes target gene recognition and tumorigenesis by MYC

MYC is an oncoprotein transcription factor that is overexpressed in the majority of malignancies. The oncogenic potential of MYC stems from its ability to bind regulatory sequences in thousands of target genes, which depends on interaction of MYC with its obligate partner, MAX. Here, we show that broad association of MYC with chromatin also depends on interaction with the WD40-repeat protein WDR5. MYC binds WDR5 via an evolutionarily conserved "MYC box IIIb" motif that engages a shallow, hydrophobic cleft on the surface of WDR5. Structure-guided mutations in MYC that disrupt interaction with WDR5 attenuate binding of MYC at ∼80% of its chromosomal locations and disable its ability to promote induced pluripotent stem cell formation and drive tumorigenesis. Our data reveal WDR5 as a key determinant for MYC recruitment to chromatin and uncover a tractable target for the discovery of anticancer therapies against MYC-driven tumors.

The ubiquitin-selective chaperone Cdc48/p97 associates with Ubx3 to modulate monoubiquitylation of histone H2B

Cdc48/p97 is an evolutionary conserved ubiquitin-dependent chaperone involved in a broad array of cellular functions due to its ability to associate with multiple cofactors. Aside from its role in removing RNA polymerase II from chromatin after DNA damage, little is known about how this AAA-ATPase is involved in the transcriptional process. Here, we show that yeast Cdc48 is recruited to chromatin in a transcription-coupled manner and modulates gene expression. Cdc48, together with its cofactor Ubx3 controls monoubiquitylation of histone H2B, a conserved modification regulating nucleosome dynamics and chromatin organization. Mechanistically, Cdc48 facilitates the recruitment of Lge1, a cofactor of the H2B ubiquitin ligase Bre1. The function of Cdc48 in controlling H2B ubiquitylation appears conserved in human cells because disease-related mutations or chemical inhibition of p97 function affected the amount of ubiquitylated H2B in muscle cells. Together, these results suggest a prominent role of Cdc48/p97 in the coordination of chromatin remodeling with gene transcription to define cellular differentiation processes.

Characterization of osteoblastic properties of 7F2 and UMR-106 cultures after acclimation to reduced levels of fetal bovine serum

Estrogen plays an important role in skeletal physiology by maintaining a remodeling balance between the activity of osteoblasts and osteoclasts. In an attempt to decipher the mechanism through which estrogen elicits its action on osteoblasts, experimentation necessitated the development of a culturing environment reduced in estrogenic compounds. The selected medium (OPTI-MEM) is enriched to sustain cultures under reduced fetal bovine serum (FBS) conditions and is devoid of the pH indicator phenol red, a suspected estrogenic agent. This protocol reduced the concentration of FBS supplementation to 0% through successive 24 h incubations with diminishing amounts of total FBS (1%, 0.1%, and 0%). The protocol does not appear to alter the viability, cell morphology, or osteoblast-like phenotype of 7F2 and UMR-106 cell lines when compared with control cells grown in various concentrations of FBS. Although the rate of mitotic divisions declined, the 7F2 and UMR-106 cultures continued to express osteoblast-specific markers and exhibited estrogen responsiveness. These experimental findings demonstrate that the culture protocol developed did not alter the osteoblast nature of the cell lines and provides a model system to study estrogen's antiresorptive role on skeletal turnover.

Nipple aspirate fluid in relation to breast cancer

Samples of breast ductal fluid can be obtained by nipple aspiration. Such samples may contain a variety of exfoliated or shed cells and display a distinctive biochemical profile reflecting the microenvironment of the ductal-alveolar system of the breast. Study of nipple aspirates may, therefore, shed light on the biology of breast cancer. This review summarizes the more important aspects of published data and explores potential avenues for future study with particular regard to molecular-biological approaches.

Patterns of referral, management and survival of patients diagnosed with prostate cancer in Scotland during 1988 and 1993: results of a national, retrospective population-based audit

OBJECTIVES

To examine patterns of referral, management and survival of men with prostate cancer, and to document changes over time.

PATIENTS AND METHODS

All men registered with prostate cancer in 1988 and 1993 were identified from the Scottish Cancer Registry. Data were abstracted according to standard definitions from the available medical records of 930 men in 1988 and 1355 in 1993.

RESULTS

There was limited evidence of multidisciplinary care, with only 8% of patients in 1988 being managed by both a urologist and a clinical oncologist within a year of diagnosis, increasing to 13% in 1993. Only a small proportion of patients were managed by clinical oncologists during the first year of care (14% in 1988 and 20% in 1993). Documentation of thorough staging information was poor, with a T stage being recorded in <30% of cases in both years. Documentation of metastatic status increased from 53% to 63% between 1988 and 1993, paralleling an increase in the use of bone scans. The proportion of cases with pathological grading obtained at diagnosis increased from 63% in 1988 to 68% by 1993. The use of PSA testing and core biopsies increased between the years while the use of transurethral prostatectomy decreased. More patients received radical radiotherapy within a year of diagnosis in 1993 than 1988, increasing from 6% to 9%, and more radical prostatectomies were also undertaken (0.2% to 2.3%). Nonetheless, most patients (81% in 1993) with no documented evidence of metastases received no active intervention (radical radiotherapy, radical prostatectomy, or 'watchful waiting'). The survival at 5 years increased nonsignificantly from 34% for the 1988 cohort to 38% for the 1993 cohort.

CONCLUSION

This audit reveals considerable inconsistency in the management of men with prostate cancer in Scotland. Against a background of controversy about numerous aspects of the management of this disease, the need for a multidisciplinary approach, comprehensive staging and appropriate documentation is highlighted.

Pilot studies on the p53 gene in nipple aspirate fluid from patients with breast cancer

Nipple Aspirate Fluid (NAF) from patients with breast cancer is a potential source of exfoliated tumour material amenable to molecular biological study, but few such data have been reported. In this study we demonstrate that polymerase chain reaction (PCR) amplification of p53 gene DNA is achievable in a proportion of NAF samples from breast cancer patients. Subsequently four NAF samples from patients whose primary tumours were identified as having a defined p53 mutation were studied by single stranded conformational polymorphism analysis (SSCP). Two samples yielded PCR product indistinguishable from wild type and two yielded no product. Whilst no cancer-related genetic mutations were demonstrated in NAF samples, further study is warranted.

p53 mutations as a marker of malignancy in bladder washing samples from patients with bladder cancer

The diagnosis and follow-up of patients with bladder cancer rely on invasive procedures (cystoscopy with biopsy). Polymerase chain reaction (PCR)-based technologies may allow the sensitive detection of cancer-related genetic mutations in exfoliated tumour material, potentially allowing the development of less invasive techniques. This pilot study investigated the feasibility of detecting mutations in exons 5-8 of the p53 gene using single-stranded conformational polymorphism (SSCP) analysis in bladder-washing specimens from patients with bladder cancer. Bladder-washing samples (31) were collected from patients (27) with bladder cancer. An abnormal additional SSCP band was detected in five samples from five different patients suggesting the presence of a p53 mutation. In all five cases the same abnormal SSCP pattern was demonstrated in samples of the corresponding bladder tumour. In one case bladder washings were available from the same patient on two separate occasions with one washing demonstrating a mutation and the other not. In two further cases a mutation was demonstrated in the bladder tumour but not in the corresponding washing. It is concluded that it is possible to detect and characterize p53 mutations in bladder-washing samples from patients with bladder cancer. Improved sensitivity in detecting mutations in a sample containing a mixture of normal and malignant cells may lead to the clinical applicability of molecular methods of disease monitoring.

Testicular seminoma in a patient with ataxia-telangiectasia

The case history of a 27-year-old man with ataxia-telangiectasia (AT) and testicular seminoma is reported. This is the first documented description of such a malignancy in AT, a syndrome associated with a markedly increased risk of malignant disease. Furthermore, alpha-foetoprotein levels have limitations as a tumour marker in this situation because serum levels may be elevated as a biochemical manifestation of AT.

In pursuit of excellence for patients with cancer: the Scottish Cancer Therapy Network model

The Scottish Cancer Therapy Network (SCTN) was created against a background of rising concerns about perceived variation in the quality of care available to patients with cancer. SCTN has established itself as a major organization with the necessary recognition and infrastructure to provide leadership, support and impetus in the field of clinical guidelines, clinical audit and clinical trials of cancer therapy in Scotland. Since being formed in 1993, SCTN has been instrumental in the development of three evidence-based, clinical guidelines and in the completion of detailed, national, retrospective audits of the treatment of five major tumour sites. The infrastructure has been used successfully to support and encourage trial participation. Challenges for the future are a re-orientation towards prospective audit, widening the constituency and sense of ownership of SCTN as a resource for practising clinicians, and further increasing recruitment into clinical trials.

Imaging of the thorax in the management of germ cell testicular tumours

AIM

To evaluate role of chest computed tomography (CTC) and chest radiography (CXR) in management of patients with testicular germ cell tumours (GCT).

PATIENTS AND METHODS

An analysis was undertaken of staging and re-assessment CTC and CXR examinations performed on patients with GCT over a 4.5-year period. Data were obtained on clinical presentation, tumour histology, tumour marker levels and clinical course. Consensus review interpretation was combined with these data to obtain a 'standard of reference'. Sensitivity, specificity and predictive values were derived by comparison of original imaging reports to 'standard of reference'.

RESULTS

Six hundred and twenty-three CTC examinations on 207 patients with GCT were included. Intrathoracic metastases were identified in 1% of seminoma patients compared with 20% of non-seminoma (NSGCT) patients. CTC was more accurate than CXR in the detection of intrathoracic metastases at 0.97, 0.96-0.98 (95% CI) compared with 0.91, 0.89-0.93. The agreement between imaging techniques and the standard of reference (determined by Kappa statistic) was respectively 0.96 for CTC and 0.65 for CXR. In GCT patients undergoing re-assessment with both CXR and CTC, CXR never detected unknown intrathoracic metastatic disease. Abdominopelvic lymphadenopathy was associated with intrathoracic metastases (P < 0.001), however re-assessment CTC did identify intrathoracic metastases in 27 cases without concurrent abdominopelvic disease. CXR was negative in 19 of these.

CONCLUSION

Routine interval CXRs are unnecessary in NSGCT patients undergoing regular re-assessment CTC due to the low additional yield and limited effect on management. Re-assessment should still include CTC. In low risk, pure seminoma patients (abdominal CT and marker negative) re-assessment CTC can be safely avoided. Baseline CTC is advocated with CXR alone for re-assessment.

Sexual function following radical radiotherapy for bladder cancer

BACKGROUND AND PURPOSE

The effect of radical radiotherapy (RT) for bladder cancer on sexual function has not been previously investigated. The current study was designed as a pilot to assess sexual function in males pre- and post-radiotherapy.

MATERIALS AND METHODS

An anonymous questionnaire was devised to examine the following sexual domains: libido, frequency of sexual function, erectile capacity, orgasm and ejaculation in the 6 months prior to radiotherapy and following treatment. Serum testosterone, FSH and LH were measured in 10 patients.

RESULTS

Eighteen patients completed the questionnaire from 10 to 56 months following irradiation, 13 of whom were able to achieve an erection prior to RT. Over half of these patients noted a decline in the quality of erections after RT, with a similar proportion noting decreased libido and frequency of sexual activity. Three patients lost the ability to have any erections whatsoever. Of the 10 patients retaining erectile capacity, three noted reduced frequency of early morning erections suggesting a physical aetiology, five had decreased frequency of ejaculation and four had reduced intensity of orgasms. Seventy-one percent (12/17) felt their sex life was worse following RT but only 56% (9/16) were concerned about the deterioration. Testosterone levels were normal in all but one patient.

CONCLUSIONS

Radical RT to the bladder can cause a decrease in sexual function in males.

Pain relief and quality of life following radiotherapy for bone metastases: a randomised trial of two fractionation schedules

BACKGROUND

The optimum dose and fractionation schedule for the palliative irradiation of painful bone metastases is controversial.

PURPOSE

To compare the efficacy, side-effects and effect on quality of life of two commonly used radiotherapy schedules in the management of painful bone metastases.

MATERIALS AND METHODS

In a prospective trial, 280 patients were randomised to receive either a single 10 Gy treatment or a course of 22.5 Gy in five daily fractions for the relief of localised metastatic bone pain.

RESULTS

Response rates have been calculated from 240 assessable treated sites of pain. The overall response rates were 83.7% (single treatment) and 89.2% (five fractions). The complete response rates were 38.8% (single treatment) and 42.3% (five fractions). The median duration of pain control was 13.5 weeks (single treatment) and 14.0 weeks (five fractions). None of these differences was statistically significant. There were no differences between the groups in the effect of treatment on a variety of quality of life parameters.

CONCLUSIONS

It is concluded that a single 10 Gy treatment is as effective as a course of 22.5 Gy in five fractions in the management of painful bone metastases.

Identification of genetic polymorphisms at the glutathione S-transferase Pi locus and association with susceptibility to bladder, testicular and prostate cancer

Two variant glutathione S-transferase cDNAs have been described at the GSTP1 locus, which differ by a single base pair (A-G) substitution at nucleotide 313 of the GSTP1 cDNA. This results in an amino acid substitution which alters the function of the enzyme. In this study, a novel PCR assay has been developed which demonstrates that these two variant cDNAs represent distinct GSTP1 alleles (GSTP1a and GSTP1b). In a study of individuals with different forms of cancer, the GSTP1b allele is found to be strongly associated with bladder cancer and testicular cancer. In controls 6.5% of individuals were homozygous for the GSTP1b allele. In bladder cancer cases, this rose to 19.7% [n = 71, odds ratio 3.6 (1.4-9.2), P = 0.006] and in testicular cancer to 18.7% [n = 155, odds ratio 3.3 (1.5-7.7), P = 0.002]. In addition, in prostate cancer a highly significant decrease in the frequency of the GSTP1a homozygotes was observed [control 51.0% versus 27.8% cancer cases, n = 36, odds ratio 0.4 (0.02-3.3), P = 0.008]. Increases in the frequency of GSTP1b homozygotes was also observed in lung cancer and chronic obstructive pulmonary disease. However, these were not statistically significant. No change in breast or colon cancer allele frequencies was observed.

The role of computed tomographic examination of the pelvis in the management of testicular germ cell tumours

AIM

To clarify the role of pelvic CT in the imaging of patients with germ cell testicular tumours (GCTT).

PATIENTS AND METHODS

A retrospective analysis was undertaken of all CT examinations performed on patients with GCTT at a regional oncological centre over a 3-year-period. Patient notes were reviewed and data on histology, tumour marker levels, therapy and clinical course obtained. The review interpretation was combined with the original radiological report and clinical data to arrive at a consensus result.

RESULTS

Four hundred and forty-three examinations on 167 patients were included. One hundred and nineteen examinations (27%) demonstrated abdominal and/or pelvic lymph node enlargement. Nodal metastasis was entirely or predominantly ipsilateral in 73/77 examinations from left-sided primary tumours (95%) and 35/42 examinations from right-sided tumours (83%). Pelvic nodal enlargement was identified in 37 examinations from 16 patients. Thirteen of these sixteen patients possessed an identifiable risk factor for pelvic nodal metastasis; the remaining three had unequivocal nodal metastases in the abdomen. Combined abdominopelvic CT increased the effective dose equivalent (EDE) by 2.6 mSv (74%) compared with abdominal examination alone. Three hundred pelvic CT examinations were performed on 117 patients without risk factors for pelvic nodal metastasis. For this cohort the radiation burden from pelvic CT was 0.78 manSv, giving a risk of induction of a single fatal cancer of 3.9%.

CONCLUSION

We advocate pelvic CT only at the time of staging, except in patients with a risk factor for pelvic nodal metastasis. Any unequivocal abdominal lymph node enlargement should be regarded as a risk factor. Implementation of this policy would safely reduce pelvic CT examinations in patients with testicular tumours by nearly 50%, with a consequent reduction in patient radiation exposures and a resource saving.

Identification of residues in alpha-macroglobulins involved in activation of the alpha 2-macroglobulin signaling receptor

Site-directed mutagenesis of residues in the receptor binding fragment of rat alpha 1-macroglobulin identify residues 1377 and 1378 (human numbering) as crucial for interaction with the alpha 2M signaling receptor on murine macrophages. Secondary structure prediction and signaling studies with the mutant proteins suggest the alpha 2M signaling receptor binding site involves part of a loop-helix-loop motif comprised of residues 1372-1378.

Characterization of alpha 2-macroglobulin binding to human trabecular meshwork cells: presence of the alpha 2-macroglobulin signaling receptor

Direct binding of receptor-recognized alpha 2-macroglobulin (alpha 2M*) or a cloned receptor binding fragment from rat alpha 1-macroglobulin (RBF) to human trabecular meshwork cells demonstrated two classes of cell surface binding sites. One class has an apparent Kd of 5.0 nM and a receptor number of 31,800 receptors/cell. The other class has an apparent Kd of 20 pM and a receptor number of 1600 receptors/cell. Binding studies of alpha 2M* or RBF in the presence of a competitor for binding to low-density-lipoprotein receptor-related protein/alpha 2M* receptor (LRP/alpha 2MR) called receptor-associated protein (RAP) show that only the lower affinity class of binding sites is susceptible to competition with RAP. Uptake studies demonstrate specific internalization and degradation of alpha 2M* which is inhibitable by RAP. Exposure of the cells to alpha 2M* and RBF (40 nM) is associated with mean increases of 171 and 210%, respectively, in the intracellular calcium concentration, which is not inhibitable by RAP or pertussis toxin. These studies present the first characterization of alpha 2M* and RBF signaling in a primary human cell type and suggest a role for alpha 2M* in the physiology of the eye.

Selective mutations in cloned and expressed alpha-macroglobulin receptor binding fragment alter binding to either the alpha2-macroglobulin signaling receptor or the low density lipoprotein receptor-related protein/alpha2-macroglobulin receptor

alpha2-Macroglobulin (alpha2M) activated with methylamine binds to two distinct cell-surface receptors: low density-lipoprotein receptor-related protein/alpha2M receptors and alpha2M signaling receptors. Binding to lipoprotein receptor-related protein/alpha2M receptor but not alpha2M signal receptor is inhibitable by another ligand, receptor-associated protein. Direct binding studies with a recombinant receptor binding fragment (RBF) from rat alpha1M and murine macrophages demonstrate two classes of binding sites of apparent Kd = 90 pM (1500 sites/cell) and 40 nM (60,400 sites/cell). Receptor-associated protein competes with RBF for binding to the lower but not the higher affinity site. Site-directed mutation of Lys-1374 (human numbering) in RBF to Arg or Ile residues almost completely abolishes signal transduction as compared to wild-type RBF. Direct binding studies with K1374R demonstrated no significant alteration in binding to the lower affinity site; however, binding to the high affinity site is reduced by 83%. Mutation of Lys-1370 to Ala resulted in a 4-5-fold increase in the Kd for binding to the lower affinity site with no significant alteration in binding to the high affinity site or signal transduction properties. Studies demonstrate comparable internalization and degradation of wild-type RBF and K1374R; however, internalization and degradation of K1370A is negligible. These studies suggest that regions around Lys-1370 and Lys-1374 are involved in lipoprotein receptor-related protein/alpha2M receptor and alpha2M signaling receptor binding, respectively.

Altered interaction of Cis-dichlorodiammineplatinum(II)--modified alpha 2-macroglobulin (alpha 2M) with the low density lipoprotein receptor-related protein/alpha 2M receptor but not the alpha 2M signaling receptor

Receptor-recognized forms of alpha 2-macroglobulin (alpha 2M*) bind to two macrophage receptors: an endocytic receptor, the low density lipoprotein receptor-related protein/alpha 2M receptor (LRP/alpha 2MR), and a G protein-coupled receptor, the alpha 2M signaling receptor (alpha 2MSR). Binding of alpha 2M* to LRP/alpha 2MR but not alpha 2MSR is inhibited by receptor-associated protein. We now present binding characteristics of alpha 2MSR (kD approximately 50 pm; 1,530 sites/cell) using Scatchard analysis. We also demonstrate that chemical modification of alpha 2M* with cis-dichlorodiammineplatinum (cis-DDP) does not significantly alter binding to either receptor or signaling characteristics as compared with unmodified alpha 2M*. However, internalization by LRP/alpha 2MR is greatly affected. Cis-DDP-modified alpha 2M* (cis-DDP-alpha 2M*) and alpha 2M* show comparable internalization during a single round of endocytosis; however, cis-DDP modification of alpha 2M* results in a > or = 82% reduction in internalization involving receptor recycling and multiple rounds of endocytosis. Results from pH 5.0 dissociation and receptor recycling experiments suggest that the mechanism of decreased internalization of cis-DDP-alpha 2M* involves poor dissociation from the receptor in endosomes and a decrease in available surface receptors over the time of exposure to the ligand.

Split course radical radiotherapy for bladder cancer in the elderly: nonsense or commonsense? A report of 76 patients

The role of split course radical radiotherapy in bladder cancer is controversial. We have pursued such a policy in elderly patients in view of the unpredictable toxicity of radical radiotherapy in this group. Between 1987 and 1992, 76 patients were treated in this way, with 2 weeks' treatment followed by a 3-week gap. Patients were then reassessed and, if considered fit enough, a further 2 weeks of treatment was given. Fifty-three patients (mean age 78.4 years) completed treatment and 23 (mean age 78 years) received phase 1 alone. Thirty-seven of 53 patients completing treatment has a follow-up cystoscopy at 6 months. Twenty-five percent of all patients, 36% of those completing treatment, and 51% of those undergoing cystoscopy, achieved a complete response. The reasons for not completing treatment and not being followed up cystoscopically are examined. We feel that this policy has a role in selected patients whose fitness to tolerate a conventional radical course of radiotherapy is in doubt.

Referral patterns within Scotland to specialist oncology centres for patients with testicular germ cell tumours. The Scottish Radiological Society and the Scottish Standing Committee of the Royal College of Radiologists

Details of 1123 patients registered in Scotland between 1983 and 1990 for testicular cancer under the Scottish Cancer Registration Scheme were obtained and compared with registrations within the five Scottish oncology centres. Some registration discrepancies were identified. Twenty-eight cancer registrations (2.5%) were coded to the wrong site, 29 patients seen at oncology centres had no cancer registration and 14 cancer registrations had the wrong histology. Five hundred and twenty-seven patients with testicular non-seminomatous germ cell tumours (NSGCT) and 567 with testicular seminoma were identified. Referral rates to specialist oncology centres for testicular germ cell tumours were measured by period and health board area of residence. For the whole study period 92% of NSGCT and 93% of seminoma patients were referred to specialist centres for treatment. Referral rates for different health board areas of residence were not significantly different. This study shows that within Scotland the majority of patients with testicular NSGCT and seminoma are referred to specialist centres, and suggests referral rates of around 92% are underestimates. Access is not related to area of residence.

A Scottish national mortality study assessing cause of death, quality of and variation in management of patients with testicular non-seminomatous germ-cell tumours. The Scottish Radiological Society and the Scottish Standing Committee of the Royal College of Radiologists

A detailed casenote review was performed on 55 patients registered with testicular non-seminomatous germ cell tumours (NSGCT) between 1983 and 1988 under the Scottish Cancer Registration Scheme and who had died by 1992. Details of all aspects of clinical management relating to their NSGCT and death details were extracted and summarised. An assessment was made on whether the patients' management had been optimal. An analysis of 5 year survival rates by the five Scottish oncology centres demonstrated significant differences between centres (range 70.4-94.2; chi 2 = 14.46, d.f. = 4, P = 0.006). Some patients in all centres were assessed as having received suboptimal treatment, but two centres performed less well than the other three. There is a suggestion that the number of patients treated suboptimally decreases with increasing number of patients seen, but this does not reach statistical significance.

A Scottish national audit of current patterns of management for patients with testicular non-seminomatous germ-cell tumours. The Scottish Radiological Society and the Scottish Committee of the Royal College of Radiologists

A detailed casenote review was performed on all 65 patients registered with testicular non-seminomatous germ cell tumours (NSGCT) during 1989 under the Scottish Cancer Registration Scheme. Details of management at presentation and 2 years following diagnosis were recorded and analysed. In a small number of patients an unacceptable delay in diagnosis was noted. Variation was found in the frequency and type of investigations performed on patients placed on surveillance, types of chemotherapy regimens used and numbers of patients entered into trials. Three per cent of patients had a biopsy of the contralateral testis and 27% of patients defaulted from clinic attendance. Considerable variation in the management of testicular NSGCT in Scotland has been identified. The introduction of management guidelines should result in a more consistent approach to the care of these patients. Support, both financial and psychological, may reduce the unacceptable rate of default.

Radiotherapy for stages I and II testicular seminoma: results and morbidity in 238 patients

We have undertaken a retrospective analysis of 238 patients with Stages I and II seminoma of the testis treated with radiotherapy in Edinburgh between 1974 and 1989. There were five deaths from seminoma. Cause-specific survival for the whole group at 2 and 5 years was 99.2% and 98.1%, respectively. Cause-specific survival at 2 and 5 years by stage (Royal Marsden staging classification) was: Stage I, 99.5% and 98.7% and Stage II, 98.1% and 96.1%. Fourteen (5.9%) patients relapsed (one after treatment for his second testicular seminoma). Eight were given successful salvage treatment, five died of seminoma and one died of intercurrent disease. 13 (5.5%) patients developed World Health Organisation (WHO) grade 3 gastrointestinal or haematological toxicity and two developed grade 4 gastrointestinal toxicity as a result of abdominal radiotherapy. 22 patients (9.2%) developed problems ascribed to late morbidity of abdominal radiotherapy including 18 with peptic ulcer disease. Contralateral testicular tumours occurred in seven (2.9%) patients and five (2.1%) patients developed malignancies at other sites.

Radical radiotherapy for localized adenocarcinoma of the prostate. A report of 191 cases

OBJECTIVE

To assess the results of radiotherapy in the treatment of localized prostate cancer. End points for assessment were survival, local control, development of metastases, and the toxicity of therapy.

MATERIALS AND METHODS

The case notes of 191 patients who were treated with radical radiotherapy between 1982 and 1992 were reviewed. The pathology of 130 patients was reviewed by a single pathologist. A multivariate analysis was performed to identify significant prognostic factors with regard to survival and relapse.

RESULTS

One-hundred and eighty-two patients were assessable. The minimum length of follow-up was one year (median = 40 months). The actuarial cause-specific 5 and 10 year survival rates were 63% and 35% respectively. Local progression occurred in 41% of patients with 37% developing metastases. Multivariate statistical analysis demonstrated that T stage and Gleason Score were significant predictors for survival. Late complications were usually mild, with only 4% developing serious bladder toxicity.

CONCLUSION

Radical radiotherapy has a role in the curative treatment of prostate cancer. Survival is significantly related to T stage at the time of presentation, and to the Gleason Score of the tumour. Survival in this series was not as good as the best surgical series, but it is still not clear which patients should receive radiotherapy and which surgery as their primary management.

Pathogenesis of acute radiation injury to the rectum. A prospective study in patients

In a prospective investigation of the clinical and pathological effects of pelvic radiotherapy on the rectum, nine patients (age range 58-77 years) had symptoms assessed weekly during radical treatment for bladder and prostatic tumours, and at 2, 4 and 12 weeks after treatment. Stool frequency increased in all patients from a mean of 1.7 per day before treatment to 5.0 per day at 4 weeks (P < 0.05). Seven patients developed liquid stools during treatment; 6 had pain on defaecation, 8 had urgency of defaecation, all experienced tenesmus and 3 had episodes of faecal incontinence. One patient had symptoms of such severity that treatment was interrupted. Virtually all symptoms had resolved by 12 weeks after treatment. Sigmoidoscopy with biopsy of anterior and posterior rectal walls was performed before treatment began, at 2 weeks and 4 weeks during treatment, and 4 and 12 weeks after treatment. All patients during treatment had evidence of acute inflammatory damage with hyperaemic, oedematous mucosa and failure of healing of biopsy sites. Histological examination of the rectal biopsies revealed the well described characteristic mucosal changes with crypt cell damage, inflammatory cell infiltrate and loss of crypts. In 2 of 7 cases studied, pathology was still abnormal at 3 months. Radiation injury to bowel is an underemphasised cause of morbidity and further prospective studies are required to determine methods of reducing normal tissue damage and ameliorating symptoms.

Negative testicular biopsy and asynchronous bilateral testicular germ cell tumour

A case is described of a patient who was recently found to have a second primary testicular cancer 3 years after his first orchidectomy and negative contralateral testis biopsy.

Seminal fluid analysis and fine-needle aspiration cytology in the diagnosis of carcinoma in situ of the testis

Surgical biopsies and fine-needle aspirates of peri-tumoural seminiferous tubules were taken from freshly-excised orchidectomy specimens. In addition, patients with suspected germ cell tumour provided a peri-operative sample of seminal fluid. All three tissue preparations were investigated using flow cytometry, immunochemistry for placental-like alkaline phosphatase and enzymochemistry for alkaline phosphatase. Biopsy and fine-needle aspiration cytology provide the greatest diagnostic accuracy for carcinoma-in-situ using these techniques. Seminal fluid analysis did not provide a satisfactory diagnostic yield in the series of patients presented. A seminal plasma placental-like alkaline phosphatase immunoassay failed to discriminate CIS because of the high level of background germ cell alkaline phosphatase.

Sexual morbidity following radiotherapy for germ cell tumours of the testis

An anonymous questionnaire study was designed to assess sexual function after orchidectomy and radiotherapy for testicular cancer. Questionnaires were sent to: (1) 237 patients treated with orchidectomy and abdominal radiotherapy in Edinburgh from 1974 to 1988; (2) 32 patients under "surveillance" following orchidectomy alone; (3) 402 "normal" age-matched controls. All were asked questions concerning sexual function over the preceding 6 months. All the patients were also asked the same questions with reference to the first 6 months after completion of treatment. Completed questionnaires were returned from 137 (62%) radiotherapy patients, 18 (56%) surveillance patients and 121 (35%) controls. There was a significant difference between the radiotherapy patients and the controls in almost all the parameters looked at including erection, ejaculation and libido with the treated group performing less well. In addition, almost 24% of the radiotherapy patients felt disabled or disfigured by the treatment, most commonly because of the presence of only one testicle. A deterioration in sexual function was observed with increasing age. In the radiotherapy group of patients there was no difference in response between the two time periods or in any of the treatment variables. The clinical significance of these observations are unclear but together with the increasing information on other toxicities emerging following this therapy the role of radiation for early stage seminoma is being brought into question. This study also confirms the morbidity of orchidectomy. We suggest that testicular implants should be offered more widely.

Idiopathic epidural lipomatosis as a cause of pain and neurological symptoms attributed initially to radiation damage

Epidural lipomatosis is a rare condition in which overgrowth of extradural fat can lead to back pain, spinal cord compression and radiculopathy. A 51-year-old man developed back pain and reduced mobility following a standard course of radiotherapy for a Stage I seminoma. His symptoms and radiological appearances were initially attributed to radiation fibrosis. Further investigations and operative intervention revealed epidural lipomatosis. The excess lipomatous tissue was removed with complete resolution of his symptoms.

Radical radiotherapy with salvage surgery for invasive bladder cancer: results following a reduction in radiation dose

The management of invasive bladder cancer in Edinburgh, as in many other centres in the UK, has been by radical radiotherapy, with cystectomy reserved for local treatment failure or relapse. A review of the results of this policy in 1987 highlighted what was felt to be an unacceptably severe morbidity rate of 15%. The dose of radiation was therefore reduced from 55 Gy in 20 daily fractions to 52.5 Gy. Forty of 80 patients (50%) treated in this way have achieved a complete response at 6 months which is a similar response rate to that in previous reports. In addition, ten of 23 frail or elderly patients (43%) achieved a complete response with a lower dose of 50 Gy given as a split course over 7 weeks. Eighteen patients have had a salvage cystectomy, and 12 of 18 (67%) are alive and disease-free. Although follow-up is short, to date toxicity has been reduced, and our results support our decision to reduce the radiation dose.

Basaloid carcinoma of the prostate gland: histogenesis and review of the literature

The clinicopathological features of a basaloid carcinoma of the prostate gland are described in a 28-year-old man, and the management and prognosis discussed. Basaloid tumours of the prostate are very rare and only a few cases have been described in detail. Those cases which have been reported as adenoid cystic carcinoma, adenoid cystic-like carcinoma and adenoid basal cell tumour are reviewed.

Neoadjuvant chemotherapy with methotrexate and cisplatin prior to radiotherapy for invasive transitional cell carcinoma of the bladder. Assessment of feasibility and toxicity

A prospective study has been performed to assess the feasibility and toxicity of administering neoadjuvant chemotherapy with methotrexate (200 mg/m2) and cisplatin (100 mg/m2) prior to radical radiotherapy. Twenty patients with advanced transitional cell carcinoma of the bladder were assessed after each of 3 courses of chemotherapy, after radiotherapy and 6 months following treatment. Of particular concern was whether neoadjuvant chemotherapy compromised the ability to give potentially curative radical radiotherapy, delayed effective palliation of distressing urinary symptoms, or allowed local tumour progression prior to definitive treatment. It was concluded that this chemotherapy regimen was well tolerated, did not compromise the ability to give radical radiotherapy and resulted in the prompt palliation of urinary symptoms. This treatment, however, did not stop the development or progression of metastatic disease in some patients. In only 1 patient was there local progression during chemotherapy.

Surgery following chemotherapy for metastatic testicular teratoma

Twenty patients with metastatic testicular teratoma underwent surgery for residual disease after chemotherapy. Twelve patients in whom complete excision of all residual masses was possible are alive with no evidence of disease. Four patients have died of malignant teratoma, 2 have active malignant disease and 2 have inoperable residual cystic disease. Patients with malignant teratoma intermediate (MTI) primary testis tumours, and those with bulky abdominal disease at presentation, are more likely to have residual masses requiring excision. Completeness of excision appears to be the most important predictor of disease-free survival.

Low dose bleomycin with etoposide and cisplatin for metastatic testicular teratoma

Thirty-nine men with metastatic testicular teratoma were treated with a combination of bleomycin, etoposide and cisplatin (BEP). Unlike the usual regimen of these 3 agents, bleomycin and cisplatin were given on day 1 only of the cycle, with etoposide for 3 days. Thirty patients (77%) are alive and disease-free after a median follow-up of 31 months--24/25 (96%) with disease confined to lymph nodes but only 6/14 (43%) patients with lung involvement. Modified BEP chemotherapy is a well tolerated alternative to standard BEP chemotherapy for small volume nodal disease; it minimises in-patient time, hospital visits and the risk of bleomycin lung toxicity. However, omission of the weekly doses of bleomycin and shortening of the administration schedule of cisplatin and etoposide may be detrimental in patients with more extensive disease, for whom more intensive therapy may be necessary.

Fertility following cancer therapy

This article reviews the literature relating to fertility following cancer therapy. Normal fertility clearly relies on normal gonadal and normal sexual function. Consideration is given here to the possible effects of surgery, radiotherapy and chemotherapy on fertility. Surgical techniques have now been described which in selected patients may allow normal erectile and ejaculatory function in the male, where previously impotence was inevitable. Maintaining radiation doses to the testes and ovaries to a minimum will reduce the incidence of radiation-induced sterility and may allow recovery of gonadal function. It is clear that cytotoxic chemotherapy does not inevitably result in permanent sterility. Some regimens are more toxic in this respect than others, and reducing the number of courses may improve the chances of retaining fertility. Hormonal manipulations designed to protect the gonad against cytotoxic damage have thus far been unsuccessful in the clinical situation.