Masatoshi Shirane

Immunohistochemical Ki67 labeling index has similar proliferation predictive power to various gene signatures in breast cancer.

The objective of this study was to examine the association between the immunohistochemical Ki67 labeling index (IHC Ki67), Ki67 mRNA expression level, and first‐generation gene signatures in a cohort of breast cancer patients. We assessed associations between IHC Ki67 and first‐generation gene signatures in a panel of 39 tumor samples, using an oligonucleotide microarray. Gene expression analyses included Ki67 alone (MKi67), 21‐gene signature, mitosis kinome score signature, and genomic grade index. Correlation coefficients were calculated by Spearmans rank correlation test. In all cases, IHC Ki67, MKi67, and three genetic markers were highly correlated (ρ, 0.71–0.97). Estrogen receptor (ER)‐positive cases showed strong correlations between IHC Ki67 and other signatures (ρ, 0.79–0.83). The ER‐negative cases showed slightly lower correlations (ρ, 0.58–0.73). In ER‐positive cases, the low IHC Ki67 group showed significantly longer relapse‐free survival than the high IHC Ki67 group (P = 0.007). This difference was confirmed by multivariate analysis. Our data indicate that IHC Ki67 shows similar predictive power for proliferation in ER‐positive cancers as genomic markers. Further study of IHC Ki67 is needed to define prognostic factors and predictive factors for chemotherapy using central laboratory assessment. (Cancer Sci, doi: 10.1111/j.1349‐7006.2012.02319.x, 2012)

Overexpression of E2F-5 correlates with a pathological basal phenotype and a worse clinical outcome

The purpose of the present study is to identify genes that contribute to cell proliferation or differentiation of breast cancers independent of signalling through the oestrogen receptor (ER) or human epidermal growth factor receptor 2 (HER2). An oligonucleotide microarray assayed 40 tumour samples from ER(+)/HER2(−), ER(+)/HER2(+), ER(−)/HER2(+), and ER(−)/HER2(−) breast cancer tissues. Quantitative reverse transcriptase PCR detected overexpression of a cell cycle-related transcription factor, E2F-5, in ER-negative breast cancers, and fluorescence in situ hybridisation detected gene amplification of E2F-5 in 5 out of 57 (8.8%) breast cancer samples. No point mutations were found in the DNA-binding or DNA-dimerisation domain of E2F-5. Immunohistochemically, E2F-5-positive cancers correlated with a higher Ki-67 labelling index (59.5%, P=0.001) and higher histological grades (P=0.049). E2F-5-positive cancers were found more frequently in ER(−)/progesterone receptor (PgR)(−)/HER2(−) cancer samples (51.9%, P=0.0049) and in breast cancer samples exhibiting a basal phenotype (56.0%, P=0.0012). Disease-free survival in node-negative patients with E2F-5-positive cancers was shorter than for patients with E2F-5-negative cancers. In conclusion, we identify, for the first time, a population of breast cancer cells that overexpress the cell cycle-related transcription factor, E2F-5. This E2F-5-positive breast cancer subtype was associated with an ER(−)/PgR(−)/HER2(−) status, a basal phenotype, and a worse clinical outcome.

Capecitabine improves cancer cachexia and normalizes IL-6 and PTHrP levels in mouse cancer cachexia models

PurposeTo clarify the potential of parathyroid hormone-related protein (PTHrP) and interleukin-6 (IL-6) as cachectic factors in a colon 26 model and the effects of capecitabine on cancer cachexia as determined by plasma levels of IL-6 and PTHrP and body weight loss.MethodsFrom two colon 26 sublines-cancer cachectic clone20 and non-cachectic clone5 plasma levels of PTHrP protein and mRNA expression levels in tumor tissues were compared. An IL-6 neutralizing antibody, a PTHrP neutralizing antibody, and capecitabine were administered into mice bearing clone20 and their anticachectic effects evaluated.ResultsThe plasma level of PTHrP protein in mice bearing clone20 was higher than that in mice bearing clone5. The expression level of PTHrP mRNA was 49-fold higher in tumor tissues of clone20 than of clone5, according to GeneChip® analysis. PTHrP antibody as well as IL-6 antibody suppressed wasting of the body and gastrocnemius and adipose tissue weights. PTHrP antibody suppressed the induction of hypercalcemia but not hypoglycemia or elevation of IL-6, whereas IL-6 antibody suppressed the induction of hypoglycemia but not hypercalcemia or elevation of PTHrP. Capecitabine, a fluorinated pyrimidine anticancer agent, improved body wasting of mice bearing clone20 at a low dose with no reduction of tumor volume. Furthermore, capecitabine lowered the levels of PTHrP and IL-6 in plasma and suppressed hypoglycemia and hypercalcemia in this model. Capecitabine also showed anticachectic effects on cachexia in a cancer model induced by human cervical cancer cell line Y (also known as Yumoto).ConclusionsPTHrP and IL-6 were found to be factors in the development of cachexia in a colon 26 cancer model, and capecitabine improved cancer cachexia by suppressing the plasma levels of IL-6 and PTHrP in colon 26 and Y cachectic models.

Continuous inhibition of epidermal growth factor receptor phosphorylation by erlotinib enhances antitumor activity of chemotherapy in erlotinib-resistant tumor xenografts

Erlotinib, an epidermal growth factor receptor tyrosine kinase inhibitor, has been shown to have benefits for non-small cell lung cancer and pancreatic cancer patients; however, almost all patients develop progressive disease during the therapy. On the other hand, it has been reported that a tumor continues to express epidermal growth factor receptor even after developing progressive disease. To demonstrate the clinical relevance of erlotinib treatment after progressive disease, we investigated whether continuous administration of erlotinib in combination with chemotherapy has a useful effect on progressive disease development during erlotinib treatment. For this purpose, we examined the antitumor effect of a combination therapy of a chemotherapeutic agent with erlotinib using two types of erlotinib-resistant tumor xenograft models: a non-small cell lung cancer model, in which EBC-1, H1975 and HCC827TR3 tumors were implanted, and an HPAC pancreatic cancer cell xenograft which generates erlotinib-resistant tumors in vivo. As a result, the combination therapy showed a significantly higher antitumor activity compared with chemomonotherapy in all xenograft models except the H1975 xenografts. Furthermore, erlotinib alone suppressed the phosphorylation of epidermal growth factor receptor in HPAC tumors and the two non-small cell lung cancer cell lines other than H1975. Therefore, combination therapy which uses erlotinib can be considered effective if epidermal growth factor receptor phosphorylation is inhibited by erlotinib, even in erlotinib-resistant tumor xenograft models. Our results suggest that the continuous inhibition of epidermal growth factor receptor phosphorylation by erlotinib after progressive disease enhances the antitumor activity of chemotherapy.

Effect of erythropoietin on human tumor growth in xenograft models

Recombinant human erythropoietin (rhEPO) has been used in the EU and the United States for the treatment of anemia in cancer patients after myelosuppressive chemotherapy or radiotherapy. However, several conflicting results have been reported concerning the detrimental effect of rhEPO on survival benefit in cancer patients. In experimental studies, contradictory results were also reported in in vitro tumor cell proliferation studies and in vivo tumor growth studies using tumor cells expressing EPO-receptor (EPO-R). Therefore, we tried to clarify the effect of epoetin β, a product of rhEPO, on tumor growth in xenograft models using five EPO-R-positive human cancer cell lines, namely the MCF7 breast, 786-O renal, SCH gastric, A549 lung and SK-OV-3 ovarian cancer cell lines. Epoetin β was administered once a week for 3 weeks at doses of 1,000, 3,000 and 10,000 IU/kg in accordance with the clinical administration schedule and dosages. As a result, no enhancement of tumor growth from the administration of epoetin β was observed in any of the xenograft models throughout the experiment duration. The effect of epoetin β on the antitumor activity of bevacizumab, an anti-angiogenic agent, was additionally examined using A549 and MCF7 xenograft models, since rhEPO reportedly stimulates tumor neovascularization. Epoetin β showed no significant effect on the antitumor activity of bevacizumab in either xenograft model. These findings suggest that epoetin β is not involved in in vivo tumor growth promotion.