We developed stromal-and epithelial-specific cre-transgenic mice to directly visualize epithelial-mesenchymal transition (EMT) during cancer progression in vivo. Using three different oncogene-driven mouse mammary tumor models and cell-fate mapping strategies, we show in vivo evidence for the existence of EMT in breast cancer and show that myc can specifically elicit this process. Hierarchical cluster analysis of genomewide loss of heterozygosity reveals that the incidence of EMT in invasive human breast carcinomas is rare, but when it occurs it is associated with the amplification of MYC. These data provide the first direct evidence for EMT in breast cancer and suggest that its development is favored by myc-initiated events. [Cancer Res 2008;68(3):937-45]

Recent breast cancer studies have highlighted the importance of interactions between cancer epithelium and tumor stroma. Recently, the focus of solid tumor investigations has shifted from mutations in carcinomatous epithelium to disturbances of tissue organization in cancer. The genetic basis of this microenvironment, however, remains to be clarified. To begin to resolve this problem, a total genome loss of heterozygosity (LOH) scan was done on epithelial and stromal DNA from 134 sporadic invasive breast carcinomas. In addition to detecting more frequent LOH at three loci in stroma than in epithelium, we found strong evidence that LOH frequencies were significantly elevated in specific regions of each chromosome. We detected 57 markers, which were preferentially lost either in stroma (n ‫؍‬ 38) or epithelium (n ‫؍‬ 19), relative to the background LOH frequencies on their respective chromosomes. This multiplicity of stromal cell LOH, and hence loss of genetic material, provides a possible mechanism for interpatient variation in host-stromal response to invading adenocarcinoma cells. This is consistent with a model in which initial, random LOH occurs equally among epithelium and stroma, but subsequent clonal selection is driven by factors, which appear to be distinctly different between malignant epithelial and surrounding stromal cells. Genetic alterations in stroma did not mimic those in epithelium, but they could play a different and parallel role in carcinogenesis and tumor progression, probably by modifying some features specific to breast cancer.

A HIGH DEGREE OF VARIABILITY IS observed in both biological behavior and clinical outcome in sporadic breast cancer, and this interpatient diversity in breast cancer biology and behavior may confound clinical management based on averages. Breast conserving surgery has become the standard of care for early stage breast cancer. In a recently published study, 2929 patients with early stage breast cancer were examined for the relative impact of the patient, the surgeon, hospital factors, or all 3 on surgical treatment outcome variation in patients with breast cancer. The study by Gort et al 1 showed that 91.2% of the total variance was attributable to the patient level (there was large interpatient variability). These data suggested that interpatient variation accounts for the high degree of clinical variability. Indeed, the demand for personalized medicine illustrates the medical community's and public's recognition of interpatient variability. It has been recognized for decades that identical chemotherapeutic regimens for similar stage and grade in patients with, for example, breast cancer (or virtually any malignancy) respond differently. Context That genomic alterations occur in both the epithelium and stroma of sporadic breast cancers has been documented by several groups. However, whether these microenvironmental alterations relate to clinicopathological features is unknown.Objective To analyze the relationship between stromal genomic alterations and presenting clinicopathological features in sporadic breast cancer. Main Outcome Measures Association of the loss of heterozygosity/allelic imbalance, in both the stroma and epithelium, with presenting clinicopathological features, such as tumor grade, expression status of estrogen receptor and progesterone receptor, human epidermal growth factor receptor 2, clinical stage, and regional lymph node metastasis status. Associations were assessed in regression models and tested with Fisher exact test. Bonferroni correction was applied to P values, with significance set at PϽ.0022. Design, Setting, and Participants

We have shown that the tumor microenvironment of sporadic breast cancer is diverse in genetic alterations and contributes to the cancer phenotype. The dynamic morphology of the mammary gland might be of special interest in hereditary breast/ovarian cancer syndrome (HBOC). We hypothesized that hotspots of loss of heterozygosity or allelic imbalance (LOH/AI) within the tumor stroma of BRCA1/2-related breast cancers provide an impaired mammary stroma that could facilitate later malignant transformation of the breast epithelium. We conducted a total genome LOH/AI scan of DNA derived from the epithelium and stroma of 51 BRCA1/2-related breast cancers, using 372 microsatellite markers. We compared these data with those from a set of 134 sporadic breast cancers. HBOC-related breast cancers accumulated significantly more genetic alterations than did sporadic breast cancers. BRCA1/2-related breast cancer stroma showed LOH/AI at 59.7% of all loci analyzed, similar to the average frequency of LOH/AI observed in the epithelium (66.2%). This is remarkably different from sporadic breast cancers, for which the average epithelial LOH/AI frequency (36.7%) far exceeds the average stromal LOH/AI frequency (28.4%) (P=.03). We identified 11 hotspot loci of LOH/AI in the BRCA1/2 stroma, encompassing genes such as POLD1, which functions in DNA replication, and SDHB. In a subset of samples, enriched for BRCA1 cases, we found 45.0% overall LOH/AI in the stroma, which was significantly higher than the 41.8% LOH/AI observed in corresponding epithelium (P=.04). Together, our data indicate that, in HBOC-related breast cancers, the accumulation of genomic instability in the cancer stroma coincides with that in the neoplastic epithelium, and we postulate that such a genetically unstable stroma might facilitate a microenvironment that functions as a landscaper that promotes genomic instability in the epithelium and, subsequently, neoplastic transformation.

Organ-specific differences in epidermal growth factor receptor (EGFR) mutational spectra and frequencies were found in lung cancer and sporadic and BRCA1/2-related breast cancers. Additionally, we found a high frequency of EGFR mutations in the tumour stroma of these invasive breast carcinomas. Those organ-specific mutational spectra and potential targets in the cancer-associated stroma might influence the efficacy of TKI therapy.

By examining 19 human cell lines derived from brain tumors for altered expression of expressed sequence tags (ESTs) in chromosomal band 4q21-22, we detected loss of expression, in 10 cell lines, of two sequences, WI6336 and WI7913. Both corresponded to the c-Jun NH 2 -terminal kinase (JNK) 3. In the present study, genomic cloning revealed that the JNK3 gene consists of 14 exons interrupted by 13 introns; its transcription-initiation site is within exon 3 and the termination codon lies in exon 14. Fluorescence in situ hybridization (FISH) and radiation-hybrid mapping confirmed the gene to 4q21-22. Together with prior evidence that, in JNK3-deficient mice, the JNK3 signaling pathway mediates apoptosis in central nervous tissue, our results suggest that loss of expression of the JNK3 gene may play an important role in the development of brain tumors in humans.

Study Type – Therapy (Phase II non‐randomized trial) Level of Evidence 2b What’s known on the subject? and What does the study add? Interim result of this study had shown promising efficacy, with response rate of 14.7% and median PFS of 7.4 months, and good tolerability of sorafenib in previously‐treated Japanese patients with metastatic RCC. Final result of the study adds: (1) the median overall survival of 25.3 months, which is longer than that in the global phase III study TARGET; (2) the response rate which elevated to 19.4% because of 6 late responders achieved after 9.2 months or longer of SD period; (3) lack of either unknown adverse events nor cumulative toxicity in the long‐term use of sorafenib. OBJECTIVE • To explore the long‐term efficacy and safety of sorafenib in Japanese patients with metastatic renal cell carcinoma (RCC) in a phase II trial. PATIENTS AND METHODS • In all, 131 Japanese patients with metastatic RCC who had received nephrectomy and failed at least one cytokine‐containing systemic therapy received continuous sorafenib 400 mg twice daily, and the efficacy and safety parameters were evaluated in these patients, including objective response rate, progression‐free survival and overall survival. RESULTS • Of the total, 129 patients were valid for intention‐to‐treat analyses and 131 patients were valid for safety analyses. • Twenty‐five patients (19.4%) had confirmed partial response and 87 patients (67.4%) had stable disease as best overall response. The 25 patients included six late‐responders who achieved response after 9.2 months or longer of stable disease. The objective response rate and disease control rate were 19.4% and 73.6%, respectively. • The median overall survival and median progression‐free survival were 25.3 and 7.9 months, respectively. • Safety profile was consistent with those previously reported, with hand–foot skin reaction (58.0%), lipase elevation (57.3%) and diarrhoea (42.7%) as the most frequently observed drug‐related adverse events. Neither unknown adverse event nor cumulative toxicity was observed over the long‐term use of sorafenib. • Despite the dose discontinuation/interruption/reduction, the mean and median relative dose intensities were 86.4% and 97.4%, respectively. CONCLUSION • The final results of this trial showed that long‐term use of sorafenib after cytokine treatment was well tolerated and provided new efficacy data, including late‐response events and favourable overall survival in Japanese patients with metastatic RCC.

Loss of heterozygosity (LOH) of chromosome 10q is observed in approximately 40% of endometrial cancers. Mutations in PTEN/MMAC1, a gene recently isolated from the 10q23 region, are responsible for two dominantly inherited neoplastic syndromes, Cowden disease and BannayanZonana syndrome. Somatic mutations of this gene have also been detected in sporadic cancers of the brain, prostate and breast. To investigate the potential role of this putative tumor suppressor gene in endometrial carcinogenesis as well, we examined 46 primary endometrial cancers for LOH at the 10q23 region, and for mutations in the entire coding region and exon-intron boundaries of the PTEN/MMAC1 gene. LOH was identified in half of the 38 informative cases, and subtle somatic mutations were detected in 15 tumors (33%). Our results suggest that of the genes studied so far in endometrial carcinomas, PTEN/MMAC1 is the most commonly mutated one, and that inactivation of both copies by allelic loss and/or mutation, a pattern that defines genes as "tumor suppressors," contributes to tumorigenesis in endometrial cancers.