Abstract P5-07-06: Kinase-independent role of cyclin D1 in chromosomal instability and mammary tumorigenesis

Cyclin D1 is an important molecular driver of human breast cancer but better understanding of its oncogenic mechanisms is needed, especially to enhance efforts in targeted therapeutics. Activation of the cyclin D1 oncogene, often by amplification or rearrangement, is a major driver of multiple types of human tumors including breast and squamous cell cancers, B-cell lymphoma, myeloma, and parathyroid adenoma. The cyclin D1 gene is amplified or overexpressed in up to half of human breast cancers and its mammary-targeted overexpression induces mammary tumorigenesis in mice. Cyclin D1 encodes the regulatory subunit of the cyclin-dependent kinase (CDK) holoenzyme that phosphorylates several substrates including the retinoblastoma protein (pRb) to advance the G1S cell cycle checkpoint, promote DNA synthesis and regulate NRF-1 to inhibit mitochondrial biogenesis thereby coordinating nuclear and mitochondrial functions.

In addition to cyclin D1's function as a regulatory subunit of a CDK holoenzyme, several CDK-independent functions have been identified. Tumors overexpressing cyclin D1 tend to display normal levels of proliferation and expression of E2F target genes, which contrasts with tumors overexpressing cyclin E or an activator for pRb. Breast cancers overexpressing cyclin D1 that are wild type for pRb have relatively normal proliferation rates, in contrast to those caused by genetic inactivation of pRb, which show significantly increased proliferation rates. Furthermore, the alternate splice form of cyclin D1, (cyclin D1b), has potent transforming ability, which does not correlate with the ability to phosphorylate the pRb protein. Several other properties of cyclin D1 have been identified including the induction of cellular migration and enhanced angiogenesis, inhibition of mitochondrial biogenesis, and mediating DNA-damage repair signaling. Cyclin D1 binding proteins participating in these putatively CDK-independent functions include PACSIN2, NRF1, and p27KIP1; binding to p27KIP1 and PACSIN2 contribute to the pro-migratory function of cyclin D1.

Currently, pharmaceutical initiatives to inhibit cyclin D1 are focused on the catalytic component since the transforming capacity is thought to reside in the cyclin D1/CDK activity. We initiated the following study to directly test the oncogenic potential of catalytically inactive cyclin D1 in an in vivo mouse model that is relevant to breast cancer. Herein, transduction of cyclin D1-/- mouse embryonic fibroblasts (MEFs) with the kinase dead KE mutant of cyclin D1 led to aneuploidy, abnormalities in mitotic spindle formation, autosome amplification, and chromosomal instability (CIN) by gene expression profiling. Acute transgenic expression of either cyclin D1WT or cyclin D1KE in the mammary gland was sufficient to induce the CIN signature within 7 days. Sustained expression of cyclin D1KE induced mammary adenocarcinoma with similar kinetics to that of the wild-type cyclin D1. ChIP-Seq studies demonstrated recruitment of cyclin D1WT and cyclin D1KE to the genes governing CIN. We conclude that the CDK-activating function of cyclin D1 is not necessary to induce either chromosomal instability or mammary tumorigenesis.

Citation Information: Cancer Res 2013;73(24 Suppl): Abstract nr P5-07-06.

PHC3, a component of the hPRC-H complex, associates with E2F6 during G0 and is lost in osteosarcoma tumors

Polyhomeotic-like 3 (PHC3) is a ubiquitously expressed member of the polycomb gene family and part of the human polycomb complex hPRC-H. We found that in normal cells PHC3 associated with both hPRC-H complex components and with the transcription factor E2F6. In differentiating and confluent cells, PHC3 and E2F6 showed nuclear colocalization in a punctate pattern that resembled the binding of polycomb bodies to heterochromatin. This punctate pattern was not seen in proliferating cells suggesting that PHC3 may be part of an E2F6-polycomb complex that has been shown to occupy and silence target promoters in G(0). Previous loss of heterozygosity (LoH) analyses had shown that the region containing PHC3 underwent frequent LoH in primary human osteosarcoma tumors. When we examined normal bone and human osteosarcoma tumors, we found loss of PHC3 expression in 36 of 56 osteosarcoma tumors. Sequence analysis revealed that PHC3 was mutated in nine of 15 primary osteosarcoma tumors. These findings suggest that loss of PHC3 may favor tumorigenesis by potentially disrupting the ability of cells to remain in G(0).

Cyclooxygenase-2 is up-regulated in proliferative inflammatory atrophy of the prostate, but not in prostate carcinoma

Cyclooxygenase-2 (COX-2) is the inducible isoform of the rate-limiting enzymes that convert arachidonic acid to proinflammatory prostaglandins as well as a primary target for nonsteroidal anti-inflammatory drugs. Accumulating evidence suggests that up-regulation of COX-2 is associated with carcinogenesis in multiple organ systems including the large bowel, lung, breast, and prostate. In this report, we examine the expression of COX-2 protein and mRNA in prostate tissue containing various lesions and in prostate cancer cell lines. In the cell lines, LNCaP, DU145, PC-3, and TSU, COX-2 protein expression was undetectable under basal conditions but could be induced transiently by phorbol ester treatment in PC-3 and TSU cells, but not in DU145 and LNCaP cells. Immunohistochemical analysis of 144 human prostate cancer cases suggested that, in contrast to several previous reports, there was no consistent overexpression of COX-2 in established prostate cancer or high-grade prostatic intraepithelial neoplasia, as compared with adjacent normal prostate tissue. Positive staining was seen only in scattered cells (<1%) in both tumor and normal tissue regions but was much more consistently observed in areas of proliferative inflammatory atrophy, lesions that have been implicated in prostatic carcinogenesis. Staining was also seen at times in macrophages. Western blotting and quantitative RT-PCR analyses confirmed these patterns of expression. These results suggest that if nonsteroidal anti-inflammatory drugs are indeed chemopreventive and/or chemotherapeutic for prostate cancer, their effects are likely to be mediated by modulating COX-2 activity in non-PCa cells (either inflammatory cells or atrophic epithelial cells) or by affecting a COX-2-independent pathway.

Intrauterine epidermal necrosis

BACKGROUND

Epidermal necrosis in a neonate is an uncommon event with a variety of potential cases.

RESULT

We report a case of intrauterine epidermal necrosis in a preterm infant, with death occurring soon after birth. The histopathology of the denuded skin revealed full-thickness epidermal necrosis and calcification within both the epidermis and follicular structures.

CONCLUSION

We believe this represents the fourth reported case of lethal intrauterine epidermal necrosis and follicular calcification.

Prognostic value of MIB-1 in advanced ovarian carcinoma as determined using automated immunohistochemistry and quantitative image analysis

BACKGROUND AND OBJECTIVES

The monoclonal antibody MIB-1 is an immunohistochemical marker reacting most strongly with cells in late S phase, G2, and M portions of the cell cycle. This antibody, reactive in formalin-fixed, paraffin-embedded tissue, allows the quantitation of a proliferation index (PI) in both current clinical cases and archival material using a computerized image analyzer (CIA).

METHODS

Since many laboratories make use of automated immunohistochemistry (AIH), this study was performed to explore the technical feasibility of using AIH (Ventana ES 320) in combination with CIA (CAS 200) to evaluate MIB-1 PI as a prognostic marker as assessed by overall survival in 50 archival (formalin-fixed, paraffin-embedded), advanced stage primary ovarian carcinomas.

RESULTS

Exploratory methods confirmed that 15% was a cutpoint that could dichotomize these 50 patients into two prognostic groups based on overall survival. The median survival of patients whose carcinoma had a high MIB-1 expression (> or = 15%) was 16 months compared with 30 months in the patients whose tumors demonstrated low MIB-1 expression (< 15%, P = 0.01). After adjustment for age, MIB-1 retained its prognostic significance (P = 0.02). Patients 60 years and older had shorter survival than younger patients (P = 0.06), but these two groups did not differ with respect to PI (P = 0.76). Those patients with a negative second look laparotomy had a longer median survival of 70 months compared with 18.5 months in patients with a positive second look (P < 0.001); the median PIs were 17% and 27%, respectively (P = 0.36). There were no significant relationships between clinical stage, nuclear grade, DNA ploidy, p53, and either survival or PI.

CONCLUSIONS

In this study, we concluded that the combination of AIH and CIA yielded a reliable quantitation of MIB-1 proliferative index and that this proliferative marker had prognostic significance in late stage ovarian carcinoma. Further studies in a larger group of patients are needed to confirm the relationship between proliferation index and other known clinicopathologic and genetic variables.

Estrogen and progesterone receptor status determined by the Ventana ES 320 automated immunohistochemical stainer and the CAS 200 image analyzer in 236 early-stage breast carcinomas: prognostic significance

The quantitation of estrogen and progesterone receptors (ER and PgR) has become the standard of care in the evaluation of patients with primary breast carcinoma. It has been demonstrated that ER and PgR detected by immunohistochemical methods in formalin-fixed paraffin-embedded tissue can be quantified by computerized image analysis. In this study, ER and PgR levels were determined by using an automated immunochemistry stainer (Ventana ES 320) and an image analyzer (CAS 200) in a series of 236 patients with stage I/II carcinoma of the breast. The degree of correlation of the ER and PgR levels determined by the dextran-coated charcoal method (DCC) with image analysis quantitation was high (r=0.75). The agreement between both methods was 77% for ER and 73% for PgR. Hormone receptor levels were correlated with prognosis as determined by overall survival. An ER level of 30 fmol/mg as determined by image analysis was established to stratify the patient population most effectively into favorable and unfavorable prognostic groups (P=0.003). An ER level of 20 fmol/mg for prognostic stratification reached statistical significance (P=0.03). The DCC method was not able to stratify the patients into prognostic groups at the traditionally accepted cutpoint of 10 fmol/mg (P=0.52). We conclude that when used in combination, automated immunohistochemistry and quantitative image analysis offer a favorable alternative to the DCC method in assessment of ER and PgR status in human mammary carcinoma. In addition, quantitative immunocytochemistry techniques may prove superior to the DCC method in specimens in which there is limited tumor volume (including fine-needle aspirates), stroma-rich tumors, and early-stage lesions including intraductal carcinoma.

Evaluation of anti-CD5 ricin A chain immunoconjugate for prevention of acute graft-vs.-host disease after HLA-identical marrow transplantation

Anti-CD5 ricin A chain immunoconjugate (XZ-CD5) is an immunotoxin that inhibits proliferative and cytotoxic responses to alloantigen in vitro and has activity in the treatment of acute graft-vs.-host disease (GVHD). To determine if XZ-CD5 could be used to prevent acute GVHD, 11 adult recipients of HLA-identical allogeneic marrow received XZ-CD5 0.1 mg kg-1 day-1 intravenously with high-dose methyl-prednisolone for 10, 14 or 17 doses early post-transplant. Six additional patients received 17 doses of XZ-CD5 and cyclosporine (CSA). All patients engrafted. Severe capillary leak syndrome was the most common serious toxicity and occurred more frequently in patients receiving CSA (5/5 vs. 3/11, P = 0.03). All evaluable patients developed acute GVHD; 88% had grade II-IV GVHD. Flow cytometric analysis demonstrated a substantial number of circulating CD5+ and CD3+ lymphocytes during and early after administration of XZ-CD5. These results suggest that the immunotoxin did not eliminate alloreactive T cells in this setting.

Effects of an anti-CD5 immunoconjugate (CD5-plus) in recent onset type I diabetes mellitus: a preliminary investigation. The CD5 Diabetes Project Team

Type-I (insulin-dependent) diabetes mellitus is an immunologically mediated disease that results in destruction of the insulin secreting beta cells of the pancreas. T cells have been implicated in the pathogenesis of this disease. One novel form of anti-T-cell therapy is the immunoconjugate CD5-Plus. This agent is composed of the murine IgG1 monoclonal antibody H65, which is directed toward the CD5+ antigen; and ricin A chain, a ribosomal inhibitor protein. We performed a pilot study to evaluate the safety of the immunoconjugate in subjects with type-I diabetes mellitus. We conducted a dose-escalation study using CD5-Plus given as an intravenous infusion for 5 consecutive days. Fifteen subjects (12 men and 3 women) with a mean age of 26 years, a mean duration of diabetes of 4.8 months, and a minimum stimulated C peptide of 0.3 pmol/mL were entered. Six subjects each were treated at the 0.1 and 0.2 mg/kg/day dosage levels, and three subjects were treated at the 0.33 mg/kg/day dose. Glycemic control was determined monthly by recording the glycohemoglobin, total daily insulin requirements, and fasting blood glucoses. Beta-cell function was measured by determining the C-peptide response to a mixed formula meal (Sustacal) at baseline and at 1,3,6,9, and 12 months after treatment. The area under the curve (AUC) of the C-peptide response was calculated and, to reduce variability, related to that of the same subject at baseline. An analysis of subjects who retained at least 80% of their baseline beta-cell function as measured by the AUC was performed.(ABSTRACT TRUNCATED AT 250 WORDS)

Phase I/II study of murine monoclonal antibody-ricin A chain (XOMAZYME-Mel) immunoconjugate plus cyclosporine A in patients with metastatic melanoma

XOMAZYME-Mel (XMMME-001-RTA) is an immunoconjugate comprised of ricin A chain conjugated to a murine monoclonal antibody directed against high molecular weight melanoma antigens. Although not necessarily related to increased toxicity or decreased efficacy, the development of anti-immunoconjugate antibodies may limit repetitive dosing with an immunoconjugate. We evaluated the role of cyclosporine A in blocking the antibody response in patients with melanoma treated with XMMME-001-RTA. Patients received cyclosporine in divided daily doses to achieve serum levels by HPLC of 150-200 ng/ml on days 1-22. On day 3, XMMME-001-RTA was begun at dosages 0.2-0.6 mg/kg daily for 5 days. Treatment was repeated every 35 days. Three patients were treated in each dosage tier (0.2, 0.4, 0.6 mg/kg). Nine patients were entered and all nine were evaluable. Patients had histologically confirmed melanoma. Metastatic sites included skin, soft tissue, and lymph nodes (seven), lung (two), liver (one), and spleen (one). There were four men and five women aged 46-75 years. Toxicities included myalgia, arthralgia, hypoalbuminemia, fatigue, elevations in liver function tests, and increased peripheral edema. Four patients received two to five repeated dosages of XMMME-001-RTA. One wheal-and-flare reaction from an immunotoxin test dose of XMMME-001-RTA was noted after five cycles. After a test dose subsequent to one cycle, two patients experienced chest tightness without ECG changes and were removed from the study. All toxicities resolved without sequelae. One patient experienced partial lymph node remission for 9 months. A second patient had stable mediastinal disease for 20 months. XMMME-001-RTA is safe when given repeatedly with cyclosporine.

Investigation and prevention of artifactual staining in flow cytometric analyses of whole blood samples from patients treated with H65-RTA, an anti-CD5 monoclonal antibody conjugated to ricin A chain

To assess the biological effect of therapeutic monoclonal antibodies (mAbs) immunoconjugates, flow cytometric assays are often performed on patients' blood samples. We report here that, using standard protocols, staining whole blood samples with mAb-fluorochromes can result in erroneous immune cell phenotyping. Blood samples were obtained from patients treated with H65-RTA, a murine IgG1 anti-CD5 mAb conjugated to ricin A chain. While a transient decrease in CD4+ and CD8+ cells was observed during the 5 days of therapy, alterations in lymphocyte phenotype were also noted, beginning around days 15-30. The most prominent effect was an apparent loss of CD4+ cells. However, if the cells were separated from plasma prior to staining, the patients' samples demonstrated their pre-treatment lymphocytic phenotypes. Co-incubation of post-treatment (day greater than or equal to 15) patients serum with lymphocytes from normal donors also resulted in artifactual staining. The effects of the post-treatment serum could be correlated with the onset of a human immune response directed against H65-RTA. Moreover, co-incubation of normal PBMC with goat anti-mouse immunoglobulin could replicate the artifactual staining patterns. Even though the human immune response was generated against a murine IgG1 mAb, there were sufficient human antibodies crossreactive with other murine IgG isotypes to induce artifactual staining with all mAb-fluorochromes tested. To minimize artifacts, cells should be separated from plasma prior to flow cytometric analysis as well as for other immunoassays involving murine mAbs.