Richard Camplejohn

Generation of an anti-tumour immune response in a non-immunogenic tumour: HSVtk killing in vivo stimulates a mononuclear cell infiltrate and a Th1-like profile of intratumoural cytokine expression

Direct delivery of the herpes simplex virus thymidine kinase (HSVtk) gene, in combination with the prodrug ganciclovir (GC), has been used for the treatment of localised, inoperable tumours. Several groups have shown that when rodent tumours are ablated in vivo with suicide genes, antitumour immunity can also be generated. Hence, this approach may also be useful in treating disseminated disease. Here we have studied the mechanisms associated with this anti‐tumour immunity. In B16 HSVtk+ tumours being killed in vivo with GSC treatment, we observed the induction of a pronounced intratumoural infiltrate of macrophages, CD4+ and CD8+ T cells. In addition, using reverse transcriptase polymerase chain reaction, expression of interleukin (IL)‐2, IL‐12, interferon‐γ (IFN‐γ), tumor necrosis factor‐α (TNF‐α) and granulocyte/macrophage colony‐stimulating factor (GM‐CSF) but not IL‐4, IL‐6 or IL‐10, was observed, a profile of cytokine expression which resembles that of a Th1 immune response. To complement these findings, we also investigated the mechanisms by which expression of HSVtk leads to cell death. Our data show that B16/HSVtk+ cells die predominantly by necrosis, rather than apoptosis, on exposure to GC, a process which may be associated with the generation of anti‐tumour inflammatory responses. From these data we propose a model for the induction of anti‐tumour immunity using suicide genes and discuss the development of improved vectors for gene therapy to augment these effects in vivo. Int. J. Cancer 71:267–274, 1997.

The relationship between c-erbB-2 expression, S-phase fraction and prognosis in breast cancer

The relationship between c-erbB-2 gene expression (assessed immunohistochemically), S-phase fraction (SPF) and prognosis has been analysed in 172 women with primary breast cancer. c-erbB-2 staining was independent of age, tumour size, number of nodes involved, tumour grade and DNA ploidy, but was more common in oestrogen receptor (ER) negative tumours (P = 0.02) and progesterone receptor (PgR) negative tumours (P = 0.03). A weak correlation between c-erbB-2 staining and SPF was observed (r = 0.18). Amongst women with node negative disease, SPF was significantly related to relapse free survival (RFS, P = 0.04) while c-erbB-2 staining was not (P = 0.2). In contrast, both SPF (P = 0.002) and c-erbB-2 staining (P = 0.016) provided significant prognostic information on RFS for women with node positive disease. Multivariate analysis showed that c-erbB-2 staining and SPF gave independent information on RFS for women with node positive disease.

Overexpression of the c-erbB-2 oncoprotein: Why does this occur more frequently in ductal carcinoma in situ than in invasive mammary carcinoma and is this of prognostic significance?

Overexpression of c-erbB-2 occurs in 60% of in situ and 25% of infiltrating ductal carcinomas. We have previously found very strong associations between immunohistochemical staining for c-erbB-2 and histological pattern and nuclear size in ductal carcinoma in situ (DCIS) and less strong correlation with proliferative activity. In a further study of infiltrating ductal carcinomas we have found that, in addition to tumours arising from c-erbB-2 positive, large celled, rapidly proliferating, comedo carcinomas and c-erbB-2 negative small celled cribriform/micropapillary carcinomas with a low proliferative rate, there is a third group of c-erbB-2 negative tumours with large nuclei and variable proliferative activity. These latter tumours are not seen in pure DCIS suggesting that they have a very transient in situ stage. Therefore, although in pure DCIS c-erbB-2 positively appears to be associated with tumours with a greater invasive potential, and c-erbB-2 negativity with tumours having a more favourable prognosis, the latter is not necessarily true in infiltrating disease.

DNA flow cytometry and response to preoperative chemotherapy for primary breast cancer.

Between October 1988 and June 1990, 22 patients with locally advanced, inoperable breast cancer entered a pilot study of four cycles of anthracycline based cytotoxic chemotherapy followed by surgery and tamoxifen. Fine needle aspirate samples of tumour were obtained for DNA flow cytometry before treatment and during the first cycle of chemotherapy. 21 patients are eligible for assessment of response and toxicity. Chemotherapy was well tolerated with greater than WHO grade 2 vomiting or stomatitis in 4 patients. Granulocytopenia less than 10(9)/l was noted in 16/21 patients but there were no episodes of neutropenic sepsis. There were 7 complete responses (CR) and 11 partial responses (PR), giving an overall response rate to chemotherapy (CR+PR) of 18/21 (86%). Responses were observed more commonly in patients who had aneuploid tumours (P = 0.06) and in patients whose tumours had a high S-phase fraction (P = 0.1). Tumours which responded to chemotherapy (CR or PR) had a significantly higher median SPF compared with tumours which did not regress (P less than 0.05). There was no consistent pattern of change in SPF values during the first cycle of chemotherapy, either for patients who responded to treatment or for those whose tumours did not regress. This combination therapy is well tolerated with a high response rate. The results of this pilot study support the recent suggestion that tumours with rapidly proliferating, aneuploid populations of cells exhibit the best short-term response to chemotherapy.

The prognostic significance of DNA flow cytometry in breast cancer: results from 881 patients treated in a single centre

In this single-centre study of 881 patients, S-phase fraction (SPF) was shown to be a significant prognostic marker in terms of overall survival (OS), relapse-free survival (RFS) and survival after relapse (SAR). Further, SPF had independent prognostic significance when considering a range of other clinicopathological variables, namely tumour grade and stage, nodal status, patient age, tumour size, menstrual status and treatment details. For OS and RFS, SPF was the second strongest predictor of the clinical course of the disease after nodal status, and for SAR it was the strongest prognostic marker. SPF correlated positively with histological grade but was the stronger predictor of survival. The distribution of SPF values was markedly different for the two ploidy classes of tumour, with DNA aneuploid tumours having a significantly higher average SPF. However, SPF retained its independent prognostic ability when DNA diploid and aneuploid tumours were analysed separately, DNA ploidy itself also proved to be an independent prognostic marker but the survival difference between the two ploidy classes was much less than that seen for different levels of SPF. Tumours with several DNA aneuploid populations (multiploid tumours) tended to have a worse prognosis than other aneuploid tumours but this trend did not reach statistical significance. In this and other studies from this centre, SPF has proved to be a robust predictor of clinical outcome in carcinoma of the breast.

Reduction of TSG101 protein has a negative impact on tumor cell growth.

TSG101 was defined originally as a tumor‐suppressor gene, raising the expectation that absence of the encoded protein should lead to increased tumor cell growth and, perhaps, increased tumor cell aggressiveness. We have used the RNA interference (RNAi) technique to downregulate TSG101 in PC3 (prostate cancer) and MDA‐MB‐231 (breast cancer) cells. An approximately 85% selective downregulation at the protein level was achieved in both cell lines over a period of 12 days as detected by Western blotting. This treatment resulted in inhibition of tumor cell growth, with a decreased level of TSG101 causing partial cell cycle arrest at the G1/S boundary and a reduction in the rate at which cells passed from G2 through mitosis and back into G1. In both cell lines, the percentage of cells in S‐phase was reduced significantly at day 4 after the TSG101 siRNA transfection (27% vs. 41% in MDA‐MB‐231 cells; 22% vs. 39% in PC3 cells). Additionally, RNAi‐mediated downregulation of TSG101 reduced the colony formation capacities of both cancer cell lines. Rather more surprisingly, TSG101 downregulation affected the migratory activity of the MDA‐MB‐231 cells, independent of any effect on proliferation. Thus, in a Transwell assay, after 4‐hr incubation, 36.0% of control MDA‐MB‐231 cells had migrated to the lower chamber vs. 7.3% of TSG101‐downregulated cells (p < 0.001; scrambled control, 36.5%). These results show that the TSG101 gene does not comply with the usual characteristics of a tumor‐suppressor gene; rather, its expression may be necessary for activities associated with aspects of tumor progression.

Apoptosis, ageing and cancer susceptibility

We have previously shown that peripheral blood lymphocytes (PBL) from individuals carrying a germline TP53 mutation show a dramatically reduced apoptotic response to radiation. As part of a study of this phenomenon, we also investigated apoptotic response in a series of breast cancer patients lacking TP53 mutations and in a control group of individuals without cancer. There was a significant reduction in mean apoptotic response with increasing age in all groups. These findings are consistent with a number of studies in rodents, which have demonstrated a reduction in DNA damage-induced apoptosis with increasing age. In addition, after adjusting for age, breast cancer patients showed significantly reduced apoptotic responses compared with normal controls (P=0.002). The odds ratio for breast cancer in women with an apoptotic response of <35%, compared with women with a response of >49%, was 6.42 (95% CI 1.68–24.6). The data further support the hypothesis that a reduction in apoptotic response to DNA damage with increasing age may play a significant role in the age-related increase in cancer.

A possible screening test for inherited p53-related defects based on the apoptotic response of peripheral blood lymphocytes to DNA damage

The cellular response, in terms of cell cycle arrest(s) and apoptosis, to radiation-induced DNA damage was studied. Experiments were performed on both mitogen-stimulated and resting peripheral blood lymphocytes (PBLs) from normal and cancer-prone (C-P) individuals. The C-P individuals comprised three patients carrying germline p53 mutations and three members of two families apparently without such mutations, but with an inherited defect which results in p53 deregulation as shown by high levels of stabilised p53 protein in normal tissues. Interestingly, mitogen-stimulated PBL, from both normal and C-P individuals failed to demonstrate a G1 arrest after gamma radiation. However, a clear difference was seen in the apoptotic response to DNA damage, of PBL from normal and C-P individuals; PBLs from C-P individuals with inherited p53-related defects had a reduced apoptotic response (P = 0.0003). There was a wide margin of separation, with no overlap between the two groups, supporting the possibility of using this altered apoptotic response as a screening test. This simple and rapid procedure could be used to identify those individuals in a C-P family who carry germline p53-related defects. The method appears to detect both individuals with p53 mutations and those apparently without mutations but with other p53-related defects.

P53, apoptosis, and breast cancer

Wild-type p53 is a tumor suppressor gene that plays a central role in maintaining the genetic integrity of the cell by preventing cells with damaged DNA from further proliferation. Mutation and deletion of p53 are the most common genetic defects seen in clinical cancer. About 40% of breast carcinomas show high levels of stabilized, often mutant, p53 protein in their cells as detected by immunohistochemistry. p53-related defects in tumor cells correlate with a poor prognosis and may also indicate a poor response to chemotherapy. In experimental systems, the p53 status of cells is important in determining their sensitivity to radiation and chemotherapeutic drugs. Cells with functional p53 die by apoptosis, whilst similar cells lacking p53 function continue to proliferate, perpetuating potentially oncogenic mutations. Not only may p53 status be a marker of the biological aggressiveness of individual tumors and of their likely response to therapy, but restoration of normal p53 function is itself already a goal of cancer therapy.

Histological grade, elastosis, DNA ploidy and the response to chemotherapy of breast cancer

The relationships between response to chemotherapy of advanced breast cancer and the histological type, grade, elastosis content and DNA ploidy of the primary tumours were examined using paraffin-embedded tissue derived from 125 patients. Higher response rates were seen amongst tumours with a high elastosis content and those that were diploid. However, selection of patients with advanced breast cancer for chemotherapy will not be assisted significantly by an assessment of these features in the primary tumour.