Association of RB/p16-Pathway Perturbations with DCIS Recurrence

Abstract

The prevalence of ductal carcinoma in situ (DCIS) diagnoses has significantly increased as a result of active radiographic screening. Surgical resection and hormone and radiation therapies are effective treatments, but not all DCIS will progress to invasive breast cancer. Therefore, markers are needed to define tumors at low risk of recurrence and progression that can be treated by surgery alone rather than by adjuvant therapies. Initial analyses indicate that retinoblastoma (RB)-pathway perturbations occur at high frequency in DCIS and mirror the molecular alterations observed in invasive breast cancer. Particularly, the elevated expression of p16ink4a in DCIS was associated with loss of RB function and estrogen receptor-negative biology. Furthermore, high expression of p16ink4a in conjunction with Ki-67 was associated with increased risk of DCIS recurrence and progression to invasive disease in multivariate analyses. These data are consistent with a functional role for RB in modulating the invasive behavior of mammary epithelial cells. The tissue microenvironment is particularly relevant to the behavior of DCIS, and, surprisingly, elevated expression of p16ink4a in nonproliferative stroma was observed in a substantial fraction of cases. In this tissue compartment, p16ink4a expression was strongly associated with disease recurrence, independent of standard histopathologic features. Together, the data herein describe dual aspects of RB-pathway biology that are associated with disease recurrence through the epithelial or stromal compartment of DCIS. (Am J Pathol

Therapeutic response to CDK4/6 inhibition in breast cancer defined by ex vivo analyses of human tumors

“…20 p16ink4a and RB were stained and scored as previously described. 7 this finding in the analyses of DCIS and breast cancer cases (in preparation). Regardless, the current data confirm the validity of the preclinical data and strongly indicate that RB status is the primary marker of drug response, followed by intense (3+) immunostaining for p16ink4a.…”

“…It is well known that cell culture models lack the tumor microenvironment known to have a significant impact on tumor biology and therapeutic response. [7][8][9] Xenograft models are dependent on the host response for the engraftment of tumor cells in non-native tissues, which do not necessarily recapitulate the nuances of complex tumor milieu. 10 In addition, genetically engineered mouse models, while enabling the tumor to develop in the context of the host, can develop tumors that do not mirror aspects of human disease.…”

Regulation of miR106b cluster through the RB pathway

“…The wound-healing assay was performed as described previously. 50,51 MCF7 cells expressing miR106B-cluster and control cells were plated on 6-cm culture plates and allowed to be confluent. Straight scratches were made on the plates, and the cells were washed and replaced with fresh medium.…”

“…Once amplified, the miR106b-cluster as well as cells expressing miR106b cluster. Cell migration/invasion assay was performed as described, 51 MCF7 cells harboring miR106B-cluster and control cells were seeded (5 × 10 4 cells) on Boyden Chambers (BioCoat 354578) under low serum conditions. Complete growth medium was added to the wells as a chemoattractant.…”

P16 but not retinoblastoma expression is related to clinical outcome in no-special-type triple-negative breast carcinomas

“…Elevated expression of p16, in conjunction with a high proliferative index, is believed to be indicative of Rb functional loss. 23,30 In recent molecular studies, Rb loss signature has been linked to poor prognosis in breast cancer patients receiving adjuvant endocrine therapy and to good prognosis in patients receiving chemotherapy. [11][12][13][14] Rb immunohistochemistry studies have provided conflicting results concerning prognosis and response to therapies, and also because of the use of different immunohistochemistry cutoff.…”