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Purpose: Cross-talk between the estrogen receptor (ER) and the phosphoinositide-3-kinase (PI3K)/Akt/mammalian target of rapamycin (mTOR) pathways is a mechanism of resistance to endocrine therapy, and blockade of both pathways enhances antitumor activity in preclinical models. This study explored whether sensitivity to letrozole was enhanced with the oral mTOR inhibitor, everolimus (RAD001)., Patients and Methods: Two hundred seventy postmenopausal women with operable ER-positive breast cancer were randomly assigned to receive 4 months of neoadjuvant treatment with letrozole (2.5 mg/day) and either everolimus (10 mg/day) or placebo. The primary end point was clinical response by palpation. Mandatory biopsies were obtained at baseline and after 2 weeks of treatment (ie, day 15). Samples were assessed for PI3K mutation status (PIK3CA) and for pharmacodynamic changes of Ki67, phospho-S6, cyclin D1, and progesterone receptor (PgR) by immunohistochemistry., Results: Response rate by clinical palpation in the everolimus arm was higher than that with letrozole alone (ie, placebo; 68.1% v 59.1%), which was statistically significant at the preplanned, one-sided, alpha = 0.1 level (P = .062). Marked reductions in progesterone receptor and cyclin D1 expression occurred in both treatment arms, and dramatic downregulation of phospho-S6 occurred only in the everolimus arm. An antiproliferative response, as defined by a reduction in Ki67 expression to natural logarithm of percentage positive Ki67 of less than 1 at day 15, occurred in 52 (57%) of 91 patients in the everolimus arm and in 25 (30%) of 82 patients in the placebo arm (P < .01). The safety profile was consistent with historical results of everolimus monotherapy; grades 3 to 4 adverse events occurred in 22.6% of patients who received everolimus and in 3.8% of patients who received placebo., Conclusion: Everolimus significantly increased letrozole efficacy in neoadjuvant therapy of patients with ER-positive breast cancer.

CrkL is a nuclear adaptor and transcriptional activator in Bcr-Abl expressing cells and constitutes the major tyrosine phosphorylated protein in CML, but the expression and biological function of CrkL in other malignancies is largely unknown. Using immunohistochemistry, we have analyzed the protein expression of activated (p)CrkL in normal and malignant tissues. We then treated K562 leukemia cells with imatinib to analyze the effect of tyrosine kinase inhibition on CrkL activation. pCrkL expression was predominantly epithelial and detected in the majority of non-malignant prostate (79%), 49% of colon biopsies, 36% of skin biopsies, and 41% of samples obtained from normal brain. Protein expression was, however, considerably less frequent in normal breast (18%), lung (16%) and ovarian (12%) tissues. In contrast to their corresponding benign tissues, pCrkL expression was significantly more common in breast cancer samples (49%, p<0.0001; Fisher's exact test), lung carcinomas (55%, p=0.0002), lymphatic tissues (80% vs. 10%, p=0.012), skin cancer (67%, p=0.020), ovarian malignomas (50%, p<0.0001) and colon carcinomas (63%, p<0.03). By contrast, activated CrkL was significantly less frequent in prostate carcinoma samples when compared to corresponding non-malignant prostatic tissues (14% vs. 79%, p<0.0001). pCrkL expression was abrogated in K562 cells with the addition of the tyrosine kinase inhibitor imatinib, which indicates that phosphorylation of CrkL is mediated through targets of therapeutic TK inhibition. We hypothesize that pCrkL is selectively up-regulated in a number of malignant tumor entities and involved in malignant transformation. We further suggest that pCrkL might serve as a potential surrogate parameter for the efficacy of therapeutic TK inhibition.

cDNA arrays provide a powerful tool to identify gene expression pattern that are potentially associated with tumor invasion and metastasis. However, genes work at the protein level and, since the transcriptional activity of a gene does not necessarily reflect cellular protein expression, the identification and quantification of proteins is essential for the understanding of molecular events leading to malignant transformation. We have therefore employed a high-throughput protein microarray system which contains 378 well-characterized monoclonal antibodies in order to compare the gene expression pattern of malignant and adjacent normal breast tissue in a patient with primary breast cancer. Using this technique, we have identified a number of proteins that show increased expression levels in malignant breast tissues such as casein kinase Ie, p53, annexin XI, CDC25C, eIF-4E and MAP kinase 7. The expression of other proteins, such as the multifunctional regulator 14-3-3e was found to be decreased in malignant breast tissue, whereas the majority of proteins remained unchanged when compared to the corresponding non-malignant samples. The protein expression pattern was confirmed by immunohistochemistry, in which antibodies against 8 representative proteins known to be involved in carcinogenesis were employed in paraffin-embedded normal and malignant tissue sections deriving from the same patient. In each case, the results obtained by IHC matched the data obtained by antibody microarray system. Taken together, we have described for the first time a tumor cell specificity protein expression pattern by use of a novel commercially available antibody microarray system. We have thus demonstrated the feasibility of high-throughput protein arrays in the proteomic analysis of human breast tissue. We hypothesize that the use of protein arrays will not only increase our understanding of the molecular events, but could prove useful in evaluating prognosis and in determining optimal antineoplastic therapy.

To determine overexpression of cathepsin D in head and neck tumours we examined cytosols from 53 primary tumours, nine cytosols of lymph node metastases and 12 cytosols from adjacent normal tissue. We found a significantly lower concentration in normal tissue compared with tumour cytosol as well as with metastases, even when we compared tumours and corresponding metastases pairwise. In addition, we found a significantly higher concentration of cathepsin D in five lymph node metastases than in the corresponding tumours. We conclude that the reported role of cathepsin D is not restricted to breast cancer but could also be important in head and neck cancer.

The amplification grade of oncogene c-erbB-2 was examined by the polymerase-chain-reaction-method in DNA's of 56 primary mammary carcinomas. 26 (46.4%) of these showed the amplified oncogene c-erbB-2. In the strongly amplified cases, the expression of the c-erbB-2 oncoprotein was verifiable immunohistochemically. Between the progesterone receptor status (PR) and the amplified c-erbB-2 oncogene there was a statistically proven dependency. No correlation was observed between the amplified c-erbB-2 oncogene and the epidermal growth-factor receptor (EGFR).

The diagnostic value of mucin-like carcinoma-associated antigen (MCA) was compared to that of carcinoembryonic antigen (CEA) and/or CA 15.3 in patients with breast cancer. A total of 368 patients with breast cancer were studied, of whom 253 were free of metastases, whereas 94 had either skeletal or visceral metastases or diffuse metastatic disease. The diagnostic sensitivity of MCA proved to be comparable to that of CA 15.3 and superior to that of CEA in patients with metastatic breast cancer. In contrast, the specificity of MCA was superior to that of CA 15.3. Finally, the diagnostic sensitivity of each of the tested tumour markers, i.e. MCA, CEA and CA 15.3, could be improved by their combined use. We conclude that MCA, either alone or in combination with CA 15.3 and CEA, can improve the monitoring of disease progression in patients with metastatic breast cancer.