Yutaka Ogasawara

PTEN activity could be a predictive marker of trastuzumab efficacy in the treatment of ErbB2-overexpressing breast cancer

Trastuzumab is the only HER2/neu-directed therapy to have received Food and Drug Administration approval for the treatment of patients with metastatic breast cancer. The efficacy of trastuzumab depends on the HER2/neu status of the tumour and the patients prior treatment, but even when patients are selected on the basis of HER2/neu gene amplification, the single-agent response rate ranges from 12 to 30% and few patients respond to trastuzumab monotherapy. Here, we propose PTEN as a predictive biomarker for trastuzumab efficacy. Human breast cancer SKBR3 and drug-resistant SKBR3/R cells were investigated. We also examined clinical samples from patients who had been treated with trastuzumab and analysed the relationship between trastuzumab efficacy and PTEN level. The PI3K/Akt signalling pathway was observed to be highly active in the drug-resistant cells, and their level of PTEN was low. Delivery of antisense PTEN duplex siRNA significantly decreased the trastuzumab chemosensitivity of parental SKBR3 cells, and marked activation of Akt signalling pathway was also recognised. Moreover, immunohistochemical investigation revealed that trastuzumab treatment was remarkably successful in cells with elevated PTEN expression. Along with the immune-system-associated cytotoxic mechanism, several mechanisms have been proposed for the effect of trastuzumab. PTEN activity might play an important and major role in its HER2/PI3K/Akt-mediated antitumour effect, and could be a useful biomarker for predicting the efficacy of trastuzumab in the treatment of breast cancer.

Proteasome inhibitors can alter the signaling pathways and attenuate the P‐glycoprotein‐mediated multidrug resistance

Numerous signaling pathways were reported to be involved in the resistance for conventional cytotoxic drugs, although one of the main reasons is the overexpression of P‐glycoprotein (P‐gp) in multidrug resistant cancer cells. The overexpression of P‐gp has been associated with the resistance to a wide range of anticancer drugs. Doxorubicin and paclitaxel are substrates of this transporter system and have an important role for the various human malignancies. In the present study, drug‐sensitive MCF7 and multidrug resistant MCF7/ADR (characterized by overexpression of P‐gp) human breast cancer cell lines were used as an experimental model. We have found that PS341 and MG132, proteasome inhibitors, reduced the degree of the multidrug resistance (MDR) in MCF7/ADR cells. This phenomenon was accompanied by a decrease in the IC50 value of doxorubicin and paclitaxel from 55.9 ± 3.46 to 0.60 ± 0.08 μM, and from 17.61 ± 1.77 to 0.59 ± 0.12 μM, respectively. The IC50 values of sensitive cells for doxorubicin and paclitaxel were about 0.42 and 0.83 μM, respectively. The effect of PS341 and MG132 on MCF7/ADR cells was associated with a significant decrease in both protein and gene levels of P‐gp expression. Moreover, with regard to the expression of possible signal transduction pathways of mitogen‐activated protein kinase (MAPK) related to the activation of mdr1, proteasome inhibitors did significantly influence the activation of these proteins. Western blot analysis revealed that 24 hr exposure of multidrug resistant MCF7/ADR cells with proteasome inhibitors did change the levels of DNA binding activity of nuclear factor‐kappaB (NF‐kappaB), pERK1/2, c‐Jun, and p‐c‐Jun. In conclusion, we could remark that proteasome inhibitors (especially PS341) attenuate the resistance of MCF7/ADR cells for P‐gp substrate drugs of doxorubicin and paclitaxel. Several proteins are supposed to be associated with the resensitization of the cells to conventional cytotoxic drugs, although decreased activity of P‐gp is at least involved in the proteasome inhibitor‐related resensitization. And influence with MAPK pathways, which have been reported to be associated with the regulation of P‐gp, might be contributed to the resensitization brought by proteasome inhibitors.

Tumor inhibitory effect of gefitinib (ZD1839, Iressa) and taxane combination therapy in EGFR-overexpressing breast cancer cell lines (MCF7/ADR, MDA-MB-231)

Some kinds of breast cancer cell lines, similar to several types of solid tumors, express epidermal growth factor receptor (EGFR). However, gefitinib, an EGFR tyrosine kinase inhibitor, is not effective for all these cell lines. Similarly, taxane is effective for many of the cell lines, although some, such as the multidrug‐resistant MCF7/ADR cell line, show taxane‐resistance. Here, we examined the growth inhibitory effect of combination treatment with gefitinib and taxane on the breast cancer cell lines MDA‐MB‐231 (EGFR‐positive) and MCF7/ADR (EGFR‐ and HER2‐positive). To estimate the combined effect, a Combination Index was calculated for each cell line. The combination of gefitinib and taxane showed a strong synergistic effect on MCF7/ADR cells, but an invitro additive‐antagonistic effect on MDA‐MB‐231 cells. Similarly, the combination treatment showed a significantly increased tumor inhibitory effect on MCF7/ADR xenografts, but not on MDA‐MB‐231 xenografts. Regarding the mechanism of the synergistic effect, Western blotting analysis revealed that taxane activated the EGFR‐Akt pathway in MCF7/ADR cells but not in MDA‐MB‐231. To determine the optimal sequential administration of gefitinib and taxane for MCF7/ADR cells, we used flow cytometry to analyze the cell cycle and apoptosis; finding that taxane treatment followed by gefitinib produced a higher rate of G2 arrest and apoptosis than gefitinib treatment followed by taxane. These results suggest gefitinib overcomes the drug‐resistance of these cells, thereby increasing the effects of taxane on MCF7/ADR cells. Further, activation of the EGFR‐Akt pathway by taxane is related to this synergistic effect.

Clinicopathological relevance of UbcH10 in breast cancer

Abrogated mitotic progression is a common hallmark of cancer. UbcH10, one of the components of the ubiquitin/proteasome pathway, plays a pivotal role in the regulation of mitotic progression. Abnormal UbcH10 activity is reported in certain types of human cancers; its overexpression is occasionally encountered in cancerous tissue compared with adjacent normal tissue. Current studies have suggested the critical role of UbcH10 in the spindle assembly checkpoint and the subsequent accurate separation of sister chromatids, which is orchestrated by a series of molecular interactions governed by the complex and diverse cell cycle machinery. To validate the potential role of UbcH10 in cell proliferation in cancer, we have analyzed the clinicopathological relevance of UbcH10 in progression of breast cancer using a combinatorial approach of human tumor arrays and biochemical analyses. Our results show that the percentage of tested samples which stained positive for UbcH10 in breast cancer tissues is significantly higher compared to the adjacent nonmalignant tissue. Furthermore, results from the clinicopathological analysis have revealed that elevated expression of UbcH10 is associated with higher histological grade tumors. In addition, depletion of UbcH10 by RNA interference in breast cancer cells resulted in decreased cellular proliferation, while overexpression of UbcH10 significantly enhanced cellular growth in breast cancer. Our results suggest a pathological correlation between UbcH10 and cell proliferation in breast cancer. Thus, aberrant UbcH10 activity may induce the dysfunction of proper cell cycle progression and result in the aggressive behavior of tumor cells in patients with breast cancer. (Cancer Sci 2009; 100: 238–248)

Clinical Significance of Preoperative Lymphoscintigraphy for Sentinel Lymph Node Biopsy in Breast Cancer

BACKGROUND Lymphoscintigraphy (LSG) has been widely used as an additional modality to sentinel lymph node biopsy (SLNB) using isotope. However, the significance of the number of LSG-visualized axillary nodes has not been fully understood. We analyzed this and discussed its potential as a modality to complement SLNB. METHODS Ninety-one breasts and axillary lymph nodal status were evaluated retrospectively. All patients were examined by LSG using isotope and subsequently by SLNB. RESULTS Nine patients (9.9%) had no LSG-visualized axillary node, while 61 patients (67.0%) had only 1 node, and 21 patients (23.1%) had multiple nodes. Overall, sentinel lymph node (SLN) identification rate was 96.7%, and the mean number of removed SLNs was 1.5 nodes per patient. In patients with nonvisualized nodes, 66.7% of SLNs were successfully identified, while 100% of SLNs were identified in those with LSG-visualized nodes. Compared with patients with less than one visualized node, significantly more SLNs were removed in patients with multiple visualized nodes. The number of LSG-visualized nodes correlated with that of metastatic nodes. CONCLUSIONS Preoperative LSG is effective in evaluating SLN status, and the LSG status could be associated with the number of dissected SLN. Moreover, the results of LSG potentially reflect the histological nodal status.

Rectal adenocarcinoma metastatic to the thyroid gland

Metastatic lesions in the thyroid are rarely reported, although microscopic metastasis to the thyroid gland is not uncommon, having been found in 4%–9% of autopsy studies. Here we present a case of rectal adenocarcinoma metastatic to the thyroid. A 28-year-old woman was admitted to the hospital for persistent anal bleeding, weight loss, and dysphagia. Physical and imaging examinations disclosed a nodule in the left lobe of the thyroid and rectal cancer in the upper rectum. Fine-needle aspiration cytology of the thyroid nodule revealed adenocarcinoma, which was consistent with a diagnosis of metastasis from the primary rectal adenocarcinoma to the thyroid. The patient died of tumor recurrence 6 months after surgery. Thyroid meta-stasis from colon and rectal carcinoma is rare, with only 11 cases appearing in the literature since 1990. The rarity and prognosis of thyroid metastasis from colon carcinoma are discussed here.

Effects of lifestyle and single nucleotide polymorphisms on breast cancer risk: a case–control study in Japanese women

BackgroundLifestyle factors, including food and nutrition, physical activity, body composition and reproductive factors, and single nucleotide polymorphisms (SNPs) are associated with breast cancer risk, but few studies of these factors have been performed in the Japanese population. Thus, the goals of this study were to validate the association between reported SNPs and breast cancer risk in the Japanese population and to evaluate the effects of SNP genotypes and lifestyle factors on breast cancer risk.MethodsA case–control study in 472 patients and 464 controls was conducted from December 2010 to November 2011. Lifestyle was examined using a self-administered questionnaire. We analyzed 16 breast cancer-associated SNPs based on previous GWAS or candidate-gene association studies. Age or multivariate-adjusted odds ratios (OR) and 95% confidence intervals (95% CI) were estimated from logistic regression analyses.ResultsHigh BMI and current or former smoking were significantly associated with an increased breast cancer risk, while intake of meat, mushrooms, yellow and green vegetables, coffee, and green tea, current leisure-time exercise, and education were significantly associated with a decreased risk. Three SNPs were significantly associated with a breast cancer risk in multivariate analysis: rs2046210 (per allele OR = 1.37 [95% CI: 1.11-1.70]), rs3757318 (OR = 1.33[1.05-1.69]), and rs3803662 (OR = 1.28 [1.07-1.55]). In 2046210 risk allele carriers, leisure-time exercise was associated with a significantly decreased risk for breast cancer, whereas current smoking and high BMI were associated with a significantly decreased risk in non-risk allele carriers.ConclusionIn Japanese women, rs2046210 and 3757318 located near the ESR1 gene are associated with a risk of breast cancer, as in other Asian women. However, our findings suggest that exercise can decrease this risk in allele carriers.

Multidetector-row computed tomography for the preoperative evaluation of axillary nodal status in patients with breast cancer

PurposeWe evaluated the effectiveness of multidetector-row computed tomography (MD-CT) for detecting axillary lymph nodal status (ALNS) in patients with breast cancer.MethodsWe reviewed 42 patients with breast cancer. A metastatic lymph node on MD-CT was defined as oval or round, with more than 5 mm on the short axis. We evaluated ALNS preoperatively by both palpation and MD-CT findings and performed sentinel lymph node biopsy (SLNB) and complete axillary lymph node dissection (ALND).ResultsFor establishing the ALNS, MD-CT showed a sensitivity of 76.9%, a specificity of 96.6%, and an accuracy of 90.5%. On the basis of the MD-CT findings, misdiagnosis was made in 4 of the 42 patients, only one of which was false positive. On the other hand, one patient with a histologically negative sentinel lymph node (SLN) result had metastasis only in a non-SLN. Preoperative MD-CT showed a positive node in this patient.ConclusionsMultidetector-row computed tomography assists in identifying women who require ALND without SLNB, with sufficient positive predictive value. Falsenegative detection by SLNB could be avoided with careful interpretation of the axillary lymph nodes shown by MD-CT.

Anaplastic thyroid carcinoma associated with granulocyte colony-stimulating factor : Report of a case

A 75-year-old woman was hospitalized due to a right axillary mass. She had undergone a resection of thyroid carcinoma 13 years earlier, followed by two subsequent operations for recurrent thyroid disease. A physical examination revealed a right axillary mass associated with skin ulceration. Persistent bleeding was observed at the skin ulcer associated with the right axillary lymph node, despite conservative treatment for the lesion. Surgery was thus performed to control persistent bleeding from the axillary ulcer, and a histopathological examination resulted in a diagnosis of poorly differentiated thyroid carcinoma. The postoperative course was uneventful, but marked leukocytosis and extensive skin metastases were recognized 30 days postoperatively. A systemic examination revealed no other lesions associated with marked leukocytosis, but elevated levels of granulocyte colony-stimulating factor were noted in a blood examination. As a result, her general condition deteriorated rapidly and the patient died 2 weeks after the onset of leukocytosis.

Clinical Significance of Multidetector-Row Computed Tomography in Breast Surgery

Abstract:  Several reports support the association of higher ipsilateral breast tumor recurrence rates with positive or intermediate margins compared with negative pathologic margins. Precise evaluation of tumor extension and adequate surgical margin are important factors affecting tumor recurrence after breast‐conserving surgery (BCS). Many studies have reported the utility of magnetic resonance imaging (MRI) for diagnosing the tumor extension of breast cancer, but few have evaluated the utility of multidetector‐row computed tomography (MDCT). The results of this study show the clinical significance of MDCT for detecting cancer extension and demonstrate the clinical role of MDCT in BCS. Subjects comprised 136 patients grouped into two categories based on whether or not tumor extension was evaluated with MDCT preoperatively. The positive surgical margin rate and breast conservation rate were analyzed in each group and the clinical role of MDCT in BCS was evaluated. Moreover, evaluation of intraductal extension was done both with MDCT and histologically, and computed tomography (CT)‐pathologic correlations were examined retrospectively. Finally, the margin‐positive cases were analyzed in relation to their clinical characteristics. Sensitivity, specificity, positive predictive value, and negative predictive value for detection of the intraductal component were 71.8%, 85.7%, 82.1%, and 76.9%, respectively. The positive surgical margin rate and conservation rate are 7.46% and 81.9%, respectively, for those who were diagnosed with MDCT preoperatively; their corresponding rates without MDCT were 16.67% and 67.9%. Most margin‐positive patients have remarkable lymphatic space invasion. Positive surgical margins were often recognized toward the nipple. For diagnosing the intraductal extension, MDCT shows sufficient diagnosability. Moreover, MDCT can provide appropriate information for the determination of adequate surgical margins and contribute to increases in breast conservation rates.