Robert I. Glazer Ph.D.

Recipient of the Mary Jo’s Fund to Fight Cancer/Joan’s Legacy Research Grant. Funded equally by Joan's Legacy and Mary Jo’s Fund to Fight Cancer.

Lay Description

Bronchioalveolar carcinoma (BAC) is a subtype of lung cancer that accounts for approximately 20% of lung cancers, including those with a mixed histology. BAC occurs more frequently among non-smokers, women and Asians, so it is likely to be unpreventable. The only potentially curative therapy for BAC is surgical removal. BAC that cannot be treated surgically has historically been considered to be resistant to chemotherapy. Therefore, it is important to search for novel ways to kill BAC and increase its sensitivity to chemotherapy, especially in late stages of the disease. We have found that 76% of 59 non-small cell lung cancer (NSCLC) tissue samples and 6/7 BAC samples expressed the stem cell marker, Musashi1 (Msi1), whereas only rare Msi1+ cells were found in normal lung tissue. Therefore, this proposal will address the hypothesis that BAC stem cell survival is dependent on the stem cell regulator, Musashi1.

Scientific Abstract

Non-small cell lung cancer (NSCLC), which includes squamous lung cancer, adenocarcinoma and large cell carcinoma, comprises 80% of lung cancers. Bronchioalveolar carcinoma (BAC) is a subtype of adenocarcinoma with growth along the alveolar septa and without evidence of stromal, vascular, or pleural invasion. Although only ~4% of lung cancers meet this definition, up to 20% of lung cancers comprise a heterogeneous group of tumors with BAC histology mixed with varying populations of invasive cells, ranging from predominant BAC histology with a mall focus of invasion, to invasive adenocarcinoma with an isolated group of cells with BAC features at the periphery. It occurs more frequently among non-smokers, women and Asians, so it is most likely to be unpreventable. The only potentially curative therapy for BAC is surgical resection. Localized BAC is treated like other NSCLC with lobar lung resection and ipsilateral mediastinal lymphadenectomy. Unresectable or metastatic BAC has historically been considered to be resistant to chemotherapy. Therefore, it is critically important to search for novel ways to kill BAC cells or increase its sensitivity to chemotherapy. Based on tissue microarray (TMA) analysis, 76% of 59 NSCLC and 6/7 BAC expressed Msi1, whereas only rare Msi1-positive cells were found in normal lung tissue. Therefore, this proposal will address the hypothesis that BAC stem cell survival is dependent on the stem cell regulator, Musashi1. These studies will focus on three specific aims:

Specific Aim #1: Determine the tumor stem cell population in BAC cell lines. Tumor cells will be grown as non-adherent spheroids in cell culture to determine the cancer stem cell phenotype by determining the percentage of cells that are CD133+ and/or CD44+/CD24lo by fluorescence-activated sort sorting (FACS).

Specific Aim#2: Determine the effect of inhibiting Msi1 expression on BAC stem cells by RNA interference using short hairpin RNA (shRNA). Msi1shRNA will be stably expressed in BAC cells that will then be characterized for tumor stem cell markers by FACS. Proliferation and apoptosis in BAC cell lines after stable expression of Msi1shRNA will be determined. Tumorigenicity of BAC stem cells stably expressing either control shRNA or Msi1shRNA will be determined by transplanting varying dilutions of cells into SCID models.

Specific Aim #3: Determine the sensitivity of BAC stem cells stably expressing either control shRNA or Msi1shRNA to therapeutic drugs. Sensitivity to gefitinib and carboplatin will be examined initially since these are the primary agents used to treat BAC. Through these Specific Aims, we expect to determine the utility of targeting Msi1 in tumor stem cells as a potential target by which to sensitize BAC to inhibition of cell growth.