Christine Laronga

Association of the Cyclin-dependent Kinases and 14-3-3 Sigma Negatively Regulates Cell Cycle Progression

14-3-3 sigma, implicated in cell cycle arrest by p53, was cloned by expression cloning through cyclin-dependent kinase 2 (CDK2) association. 14-3-3 sigma shares cyclin-CDK2 binding motifs with different cell cycle regulators, including p107, p130, p21CIP1, p27KIP1, and p57KIP2, and is associated with cyclin·CDK complexesin vitro and in vivo. Overexpression of 14-3-3 sigma obstructs cell cycle entry by inhibiting cyclin-CDK activity in many breast cancer cell lines. Overexpression of 14-3-3 sigma can also inhibit cell proliferation and prevent anchorage-independent growth of these cell lines. These findings define 14-3-3 sigma as a negative regulator of the cell cycle progression and suggest that it has an important function in preventing breast tumor cell growth.

The incidence of occult nipple-areola complex involvement in breast cancer patients receiving a skin-sparing mastectomy

Background: Surgical treatment of breast cancer traditionally has included resection of the nipple-areola complex (NAC), in the belief that this area had a significant probability of containing occult tumors. The purpose of this study was to investigate the true incidence of NAC involvement in patients who underwent a skin-sparing mastectomy (SSM) and to determine associated risk factors.Methods: A retrospective chart review was conducted of 326 patients who had a SSM at our institution from 1990 to 1993. NAC involvement was reviewed in 286 mastectomy specimens. The charts were analyzed for tumor size, site, histology, grade, nodal status, recurrence, survival, and NAC involvement.Results: Occult tumor involvement in the NAC was found in 5.6% of mastectomy specimens (16 patients). Four patients would have had NAC involvement identified on frozen section if they had been undergoing a skin-sparing mastectomy with preservation of the NAC. There were no significant differences between NAC-positive (NAC+) and NAC-negative (NAC-) patients in median tumor size, nuclear grade, histologic subtype of the primary tumor, or receptor status. There were significant differences in location of the primary tumor (subareolar or multicentric vs. peripheral) and positive axillary lymph node status. NAC involvement was not a marker for increased recurrence or decreased survival.Conclusions: Occult NAC involvement occurred in only a small percentage of patients undergoing skin-sparing mastectomies. NAC preservation would be appropriate in axillary node-negative patients with small, solitary tumors located on the periphery of the breast.

A novel approach toward development of a rapid blood test for breast cancer

Mammography remains the diagnostic test of choice for breast cancer, but 20% of cancers still go undetected. Many serum biomarkers have been reported for breast cancer but none have proven to represent effective diagnostic strategies. ProteinChip mass spectrometry is an innovative technology that searches the proteome for differentially expressed proteins, allowing for the creation of a panel or profile of biomarkers. The objective of this study was to construct unique cancer-associated serum profiles that, combined with a classification algorithm, would enhance the detection of breast cancer Pretreatment serum samples from 134 female patients (45 with cancer, 42 with benign disease, 47 normal) were procured prospectively following institutional review board-approved protocols. Proteins were denatured, applied onto ProteinChip affinity surfaces, and subjected to surface enhanced laser desorption/ionization (SELDI) time-of-flight mass spectrometry. The SELDI output was analyzed using Biomarker Pattern Software to develop a classification tree based on group-specific protein profiles. The cross-validation analysis of cancer versus normal revealed sensitivity and specificity rates of 80% and 79%, and for cancer versus benign disease, 78% and 83%, respectively. When 2 different chip surfaces were combined the sensitivity and specificity increased to 90% and 93%, respectively. The sensitivity and specificity of this technique are comparable to those of mammography and, if confirmed in a larger study, this technique could provide the means toward development of a simple blood test to aid in the early detection of breast cancer. The combination of SELDI ProteinChip mass spectrometry and a classification- and regression-tree algorithm has the potential to use serum protein expression profiles for detection and diagnosis of breast cancer.

Pharmacoproteomic analysis of prechemotherapy and postchemotherapy plasma samples from patients receiving neoadjuvant or adjuvant chemotherapy for breast carcinoma.

In this study, proteomic changes were examined in response to paclitaxel chemotherapy or 5‐fluorouracil, doxorubicin, and cyclophosphamide (FAC) chemotherapy in plasma from patients with Stage I–III breast carcinoma. The authors also compared the plasma profiles of patients with cancer with the plasma profiles of healthy women to identify breast carcinoma–associated protein markers.

Micrometastasis in the sentinel lymph node of breast cancer does not mandate completion axillary dissection.

Objective:To determine if micrometastatic disease in the sentinel lymph node is a predictor of non-sentinel lymph node (non-SLN) involvement in breast cancer. Summary Background Data:Sentinel lymph node biopsy (SLN) is an accepted alternative to axillary dissection in staging breast cancer. If the SLN contains metastatic foci, the standard recommendation is completion axillary node dissection (CAD). However, a large subset of patients with metastasis limited to the SLN is unnecessarily subjected to the morbidity of CAD. Methods:A retrospective review of prospectively gathered breast cancer patients having SLN was conducted. Patients with metastasis to the SLN were selected for analysis. Various clinicopathologic features were analyzed for association with metastasis to the non-SLN. Results:A total of 194 women underwent successful SLN dissection. Metastasis to the SLN was found in 48 patients (21 had micrometastases, 27 had macrometastases). Of those with micrometastases, 16 underwent CAD with 1 patient having metastasis to the non-SLN. In patients with macrometastases, 26 had CAD with 14 patients having non-SLN metastasis. Multivariable logistic regression identified only macrometastatic disease in the SLN as significantly associated with involvement of the non-SLN (P = 0.03). None of the patients with micrometastases, including those without CAD, has evidence of local recurrence to date (3–30 months). Conclusion:This study demonstrates that the incidence of non-SLN involvement is low in SLN that contains only micrometastatic foci and is within the accepted range of the false-negative rate of SLN. This suggests that a CAD may be omitted in patients with micrometastatic disease.

Lymphedema of the Arm and Breast in Irradiated Breast Cancer Patients: Risks in an Era of Dramatically Changing Axillary Surgery

Abstract:  The purpose of this study was to assess risk for lymphedema of the breast and arm in radiotherapy patients in an era of less extensive axillary surgery. Breast cancer patients treated for cure were reviewed, with a minimum follow‐up of 1.5 years from the end of treatment. Clinical, surgical, and radiation‐related variables were tested for statistical association with arm and breast lymphedema using regression analyses, t‐tests, and chi‐squared analyses. Between January 1998 and June 2001, 240 women received radiation for localized breast cancer in our center. The incidence of lymphedema of the ipsilateral breast, arm, and combined (breast and arm) was 9.6%, 7.6%, and 1.8%, respectively, with a median follow‐up of 27 months. For breast edema, t‐test and multivariate analysis showed body mass index (BMI) to be significant (p = 0.043, p = 0.0038), as was chi‐squared and multivariate testing for site of tumor in the breast (p = 0.0043, p = 0.0035). For arm edema, t‐test and multivariate analyses showed the number of nodes removed to be significant (p = 0.0040, p = 0.0458); the size of the tumor was also significant by multivariate analyses (p = 0.0027). Tumor size appeared significant because a number of very large cancers failed locally and caused cancer‐related obstructive lymphedema. In our center, even modern, limited level 1–2 axillary dissection and tangential irradiation carries the risk of arm lymphedema that would argue in favor of sentinel node biopsy. For breast edema, disruption of draining lymphatics by surgery and radiation with boost to the upper outer quadrant increased risk, especially for the obese. Fortunately both breast and arm edema benefited from manual lymphatic drainage. 

SELDI-TOF serum profiling for prognostic and diagnostic classification of breast cancers

Surface enhanced laser desorption/ionization (SELDI) time-of-flight mass spectrometry has emerged as a successful tool for serum based detection and differentiation of many cancer types, including breast cancers. In this study, we have applied the SELDI technology to evaluate three potential applications that could extend the effectiveness of established procedures and biomarkers used for prognostication of breast cancers. Paired serum samples obtained from women with breast cancers prior to surgery and post-surgery (6–9 mos.) were examined. In 14/16 post-treatment patients, serum protein profiles could be used to distinguish these samples from the pre-treatment cancer samples. When compared to serum samples from normal healthy women, 11 of these post-treatment samples retained global protein profiles not found in healthy women, including five low-mass proteins that remained elevated in both pre-treatment and post-treatment serum groups. In another pilot study, serum profiles were compared for a group of 30 women who were known BRCA-1 mutation carriers, half of whom subsequently developed breast cancer within three years of the sample procurement. SELDI protein profiling accurately classified 13/15 women with BRCA-1 breast cancers from the 15 non-cancer BRCA-1 carriers. Additionally, the ability of SELDI to distinguish between the serum profiles from sentinel lymph node positive and sentinel lymph node negative patients was evaluated. In sentinel lymph node positive samples, 22/27 samples were correctly classified, in comparison to the correct classification of 55/71 sentinel lymph node negative samples. These initial results indicate the utility of protein profiling approaches for developing new diagnostic and prognostic assays for breast cancers.

Prevalence, predictors, and characteristics of off‐treatment fatigue in breast cancer survivors

Lack of consensus regarding how to identify cancer patients with significant fatigue has hampered research regarding cancer‐related fatigue (CRF).

Surfaced-Enhanced Laser Desorption/Ionization Time-of-Flight (SELDI-TOF) Differentiation of Serum Protein Profiles of BRCA-1 and Sporadic Breast Cancer

AbstractBackground: BRCA-1 mutations predispose women to early onset breast cancer, but ∼20% never develop cancer. Surface-enhanced laser desorption/ionization time-of-flight mass spectrometry (SELDI-TOF MS) profiling can differentiate protein signatures of cancer and normal subjects. Our objective was to distinguish women with BRCA-1 mutations who developed breast cancer (BRCA-1 Ca) from those who did not (Carrier), normal volunteers (NL), and women with sporadic breast cancer (SBC), using SELDI-TOF. Methods: Baseline serum specimens were obtained from women with BRCA-1 mutations without cancer, SBC, and NL. BRCA-1 women were later divided into two cohorts, pending cancer development. The sera were spotted onto protein chips for SELDI-TOF analysis and analyzed with classification algorithm software. Results: BRCA-1 Ca patients (n = 15) developed cancer within 3 years of baseline, while BRCA-1 carriers (n = 15) were cancer-free in 7 years of follow-up. SELDI-TOF analysis revealed differentially expressed proteins (P < .05) between BRCA-1 Ca, Carrier, and SBC patients (n = 16), such that 13/15 BRCA-1 Ca vs. Carrier women were correctly identified (sensitivity/specificity of 87%/87%) and 14/15 BRCA-1 Ca vs. SBC patients were correctly identified (sensitivity/specificity 94%/100%). Profiles of Carriers resembled NL profiles (n = 16). Conclusions: SELDI-TOF protein profiles from this small pilot study distinguished between women with BRCA-1 Ca, Carriers, and women with SBC. Whether BRCA-1 Ca represents earlier detection of occult cancer or other risk factors is unknown. Follow-up studies with larger numbers and longer follow-up are required to validate these findings but may allow more timely prophylactic or therapeutic strategies.

DNA Damage–Induced Protein 14-3-3 σ Inhibits Protein Kinase B/Akt Activation and Suppresses Akt-Activated Cancer

14-3-3 sigma is induced by tumor suppressor protein p53 in response to DNA damage. p53 can directly transactivate the expression of 14-3-3 sigma to cause a G(2) cell cycle arrest when cell DNA is damaged. The expression of 14-3-3 sigma protein is down-regulated in various tumors, but its function has not been fully established. Protein kinase B/Akt, a crucial regulator of oncogenic signal involved in cell survival and proliferation, is deregulated in many types of cancer. Akt activation can enhance p53 degradation, but its role in DNA damage response is not clear. Here, we show that Akt activation is diminished when p53 and 14-3-3 sigma is up-regulated in response to DNA damage. Evidence is provided that 14-3-3 sigma binds and inhibits Akt. In keeping with this concept, Akt-mediated cell survival is inhibited by 14-3-3 sigma. Significantly, we show that 14-3-3 sigma inhibits Akt-mediated cell growth, transformation, and tumorigenesis. Low expression of 14-3-3 sigma in human primary breast cancers correlates with Akt activation. These data provide an insight into Akt regulation and rational cancer gene therapy by identifying 14-3-3 sigma as a molecular regulator of Akt and as a potential anticancer agent for Akt-activated cancers.