The regulation of ER-α transcription by pRb2/p130 in breast cancer

Case Report: Durable partial response to icotinib plus crizotinib in a lung adenocarcinoma patient with double uncommon EGFR G719D/L861Q mutations and an acquired novel CUX1-MET fusion

Non-small cell lung cancer (NSCLC) patients harboring MET exon 14 skipping or high MET amplification display a high rate of response to MET inhibitors. However, MET fusions in NSCLC have rarely been revealed. In this report, a 63-year-old woman with lung adenocarcinoma (LADC), harboring EGFR exon 18 G719D and exon 21 L861Q mutations, received first-generation, EGFR-tyrosine kinase inhibitor (TKI) icotinib therapy. Next generation sequencing (NGS) results only displayed an EGFR T790M point mutation following icotinib resistance. Thus, the patient was treated with osimertinib and achieved a stable disease (SD). However, disease progressed after 15 months and a novel MET fusion (CUX1 exon14-MET exon15) in addition to EGFR G719D/L861Q mutations were simultaneously detected in a tissue biopsy sample. After more than nine months, the patient subsequently achieved a PR with the combination of icotinib and crizotinib. To our knowledge, this is the first case of LADC patient displaying the presence of EGFR double uncommon mutations and an acquired novel CUX1-MET fusion that has benefited from icotinib plus crizotinib treatment. Following nine months of PR with icotinib plus crizotinib, the patient, until the time of publication, is exhibiting stable disease. The results suggest that the CUX1-MET fusion may be sensitive to crizotinib, although previous reports indicated that some MET fusion cases did not respond to crizotinib. Given this disparity, distinguishing MET fusion partners when crizotinib is used in LADC treatment is also very important.

AGTR1 Inhibits the Progression of Lung Adenocarcinoma

Purpose

The occurrence and development of lung adenocarcinoma (LUAD) are related to many factors. Multiple researches showed that the renin-angiotensin system (RAS) plays an important role in lung cancer. This research mainly focuses on angiotensin II receptor 1 (AT1R) encoding gene AGTR1, an important part of the RAS.

Methods

We comprehensively evaluated the expression of AGTR1 in pan-cancer based on RNA sequencing data obtained from The Cancer Genome Atlas (TCGA). We explored the correlation of AGTR1 with clinicopathological features, prognosis and tumor microenvironment in LUAD. We also explored the mechanism through enrichment analysis and verified it with cell lines and tissue samples.

Results

We found that AGTR1 was less expressed in most tumors and related to prognosis based on the TCGA database. To further explore its mechanism, we mainly focused on LUAD. Combined with the verification results in the GEO database, AGTR1 was associated with a better prognosis in LUAD. High expression of AGTR1 was associated with less lymph node metastasis (P=0.007) and MET mutation (P=0.019). High expression of AGTR1 was related to the anti-tumor immune microenvironment with high infiltration of B cells, myeloid dendritic cells, monocytes, and low infiltration of myeloid-derived suppressor cells (all P<0.05). Enrichment analysis and in vitro verification results showed that AGTR1 was likely to play a role in LUAD through the PI3K/AKT3 pathway. Finally, we verified the above results through tissue samples and the construction of AGTR1 overexpressing cells.

Conclusion

AGTR1 inhibits the progression of lung adenocarcinoma through the PI3K/AKT3 pathway.

Integrative network-based approach identifies key genetic elements in breast invasive carcinoma

BACKGROUND

Breast cancer is a genetically heterogeneous type of cancer that belongs to the most prevalent types with a high mortality rate. Treatment and prognosis of breast cancer would profit largely from a correct classification and identification of genetic key drivers and major determinants driving the tumorigenesis process. In the light of the availability of tumor genomic and epigenomic data from different sources and experiments, new integrative approaches are needed to boost the probability of identifying such genetic key drivers. We present here an integrative network-based approach that is able to associate regulatory network interactions with the development of breast carcinoma by integrating information from gene expression, DNA methylation, miRNA expression, and somatic mutation datasets.

RESULTS

Our results showed strong association between regulatory elements from different data sources in terms of the mutual regulatory influence and genomic proximity. By analyzing different types of regulatory interactions, TF-gene, miRNA-mRNA, and proximity analysis of somatic variants, we identified 106 genes, 68 miRNAs, and 9 mutations that are candidate drivers of oncogenic processes in breast cancer. Moreover, we unraveled regulatory interactions among these key drivers and the other elements in the breast cancer network. Intriguingly, about one third of the identified driver genes are targeted by known anti-cancer drugs and the majority of the identified key miRNAs are implicated in cancerogenesis of multiple organs. Also, the identified driver mutations likely cause damaging effects on protein functions. The constructed gene network and the identified key drivers were compared to well-established network-based methods.

CONCLUSION

The integrated molecular analysis enabled by the presented network-based approach substantially expands our knowledge base of prospective genomic drivers of genes, miRNAs, and mutations. For a good part of the identified key drivers there exists solid evidence for involvement in the development of breast carcinomas. Our approach also unraveled the complex regulatory interactions comprising the identified key drivers. These genomic drivers could be further investigated in the wet lab as potential candidates for new drug targets. This integrative approach can be applied in a similar fashion to other cancer types, complex diseases, or for studying cellular differentiation processes.

Genetic alterations in oral squamous cell carcinoma progression detected by combining array-based comparative genomic hybridization and multiplex ligation-dependent probe amplification

BACKGROUND

Oral squamous cell carcinoma (OSCC), the most common malignancy of the oral cavity, has been shown to occur via a multistep process driven by the accumulation of carcinogen-induced genetic changes.

STUDY DESIGN

Array-based comparative genomic hybridization (aCGH) and multiplex ligation-dependent probe amplification (MLPA) were conducted to screen human genomewide alterations on fresh tissues of the cancer area, the dysplastic transitional area, and the resection margin (normal) free of tumor; these samples were obtained from 7 OSCC patients.

RESULTS

The highest amplification frequencies (100%, 7/7) were detected in FAM5B, TIPARP, PIK3CA, NLGN1, FGF10, HDAC9, GRM3, DDEF1, EDNRB, CHRDL1, and HTR2C, and the highest deletion frequencies in THRAP3, CTTNBP2NL, GATAD2B, REL, CKAP2L, RHOA, EIF4E3, PDLIM5, FBXO3, NEUROD4, and ABCA5 in the OSCC. In the dysplasia, amplification (100%, 7/7) was detected in RNF36 and deletion in CKAP2L and TCF8. We could detect large differences with MLPA in the number of alterations between the cancer or dysplasia versus the normal area with P values of <.001.

CONCLUSION

These findings indicate that these DNA copy number changes on each chromosome in the 3 categories may be associated with OSCC tumorigenesis and/or progression.

Brassinosteroids cause cell cycle arrest and apoptosis of human breast cancer cells

Brassinosteroids (BRs) are plant hormones that appear to be ubiquitous in both lower and higher plants. Recently, we published the first evidence that some natural BRs induce cell growth inhibitory responses in several human cancer cell lines without affecting normal non-tumor cell growth (BJ fibroblasts). The aim of the study presented here was to examine the mechanism of the antiproliferative activity of the natural BRs 28-homocastasterone (28-homoCS) and 24-epibrassinolide (24-epiBL) in human hormone-sensitive and -insensitive (MCF-7 and MDA-MB-468, respectively) breast cancer cell lines. The effects of 6, 12 and 24h treatments with 28-homoCS and 24-epiBL on cancer cells were surveyed using flow cytometry, Western blotting, TUNEL assays and immunofluorescence analyses. The studied BRs inhibited cell growth and induced blocks in the G(1) cell cycle phase. ER-α immunoreactivity was uniformly present in the nuclei of control MCF-7 cells, while cytoplasmic speckles of ER-α immunofluorescence appeared in BR-treated cells (IC(50), 24h). ER-β was relocated to the nuclei following 28-homoCS treatment and found predominantly at the periphery of the nuclei in 24-epiBL-treated cells after 24h of treatment. These changes were also accompanied by down-regulation of the ERs following BR treatment. In addition, BR application to breast cancer cells resulted in G(1) phase arrest. Furthermore, TUNEL staining and double staining with propidium iodide and acridine orange demonstrated the BR-mediated induction of apoptosis in both cell lines, although changes in the expression of apoptosis-related proteins were modulated differently by the BRs in each cell line. The studied BRs seem to exert potent growth inhibitory effects via interactions with the cell cycle machinery, and they could be highly valuable leads for agents for managing breast cancer.

Wilms' tumor 1 suppressor gene mediates antiestrogen resistance via down-regulation of estrogen receptor-alpha expression in breast cancer cells

The antiestrogen tamoxifen has been used in the treatment of hormone-responsive breast cancer for over a decade. The loss of estrogen receptor (ER) expression is the most common mechanism for de novo antiestrogen resistance. Wilms' tumor 1 suppressor gene (WT1) is a clinically useful marker that is associated with poor prognosis in breast cancer patients; its high level expression is frequently observed in cases of breast cancer that are estrogen and progesterone receptor negative. The lack of expression of these receptors is characteristic of tumor cells that are not responsive to hormonal manipulation. To determine whether there is a linkage between WT1 expression and antiestrogen resistance in breast cancer cells, we studied the effect of WT1 on tamoxifen responsiveness in ERalpha-positive MCF-7 cells. We found that overexpression of WT1 in MCF-7 markedly abrogated tamoxifen-induced cell apoptosis and 17beta-estradiol (E(2))-mediated cell proliferation. The expressions of ERalpha and its downstream target genes were significantly repressed following overexpression of WT1, whereas the down-regulation of WT1 by WT1 shRNA could enhance ERalpha expression and the sensitivity to tamoxifen treatment in ERalpha-negative MDA468 and HCC1954 cells that express high levels of WT1. Furthermore, we have confirmed that the WT1 protein can bind to endogenous WT1 consensus sites in the proximal promoter of ERalpha and thus inhibit the transcriptional activity of the ERalpha promoter in a WT1 site sequence-specific manner. Our study clearly implicates WT1 as a mediator of antiestrogen resistance in breast cancer through down-regulation of ERalpha expression and supports the development of WT1 inhibitors as a potential means of restoring antiestrogen responsiveness in breast cancer therapy.

Rb family proteins as modulators of gene expression and new aspects regarding the interaction with chromatin remodeling enzymes

The pRb family proteins (pRb1/105, p107, pRb2/p130), collectively referred to as pocket proteins, are believed to function primarily as regulators of the mammalian cell cycle progression, and suppressors of cellular growth and proliferation. In addition, different studies suggest that these pocket proteins are also involved in development and differentiation of various tissues. Several lines of evidence indicate that generally pRb-family proteins function through their effect on the transcription of E2F-regulated genes. In fact, each of Rb family proteins binds to distinct members of the E2F transcription factors, which regulate the expression of genes whose protein products are necessary for cell proliferation and to drive cell-cycle progression. Nevertheless, pocket proteins can affect the G1/S transition through E2F-independent mechanisms. More recently, a broad range of evidences indicate that pRb-family proteins associate with a wide variety of transcription factors and chromatin remodeling enzymes forming transcriptional repressor complexes that control gene expression. This review focuses on the complex regulatory mechanisms by which pRb-family proteins tell genes when to switch on and off.

Nuclear and cytoplasmic interaction of pRb2/p130 and ER-β in MCF-7 breast cancer cells

Estrogens exhibit important biological functions and influence several pathological processes of hormone-dependent diseases. The biological actions of estrogens require their interaction with two estrogen receptors (ER-alpha and ER-beta), which are ligand-dependent transcription factors. ER-alpha and ER-beta exhibit distinct tissue expression patterns as well as show different patterns of gene regulation. In addition, it has been suggested that ER-beta works as a counter partner of ER-alpha through inhibition of the transactivating functions of ER-alpha. For instance, ER-beta seems to play a different role in breast tumorigenesis than ER-alpha, as ER-beta decreased expression in breast cancer has been correlated with bad prognosis. Biological activities of ER-alpha and ER-beta could be controlled by a number of interacting proteins such as activators/inhibitors, ligand binding and kinases. We have previously reported that pRb2/p130, retinoblastoma related protein, could be involved in the silencing of ER-alpha gene during breast tumorigenesis. Here, we report that ER-beta and pRb2/p130 proteins co-immunoprecipitate in both nucleus and cytoplasm of MCF-7 breast cancer cells. Our hypothesis is that the interaction of pRb2/130 with ER-beta may have a functional significance in regulating ER-beta activity.

Multidisciplinary International Conference on Gynecologic Cancer, Bologna, Italy, June 8-12, 2005

The first "Multidisciplinary International Conference on Gynecologic Cancer" which was held in Bologna on June 8-12, 2005, addressed some of the most crucial topics in gynecologic oncology, presented the latest achievements and, at the same time, designed the guidelines for future developments in the field. The scientific program was intended not only to share and compare views and ideas among gynecologists but also with oncologists and researchers in basic science. The scientific committee strongly believed in the "multidisciplinary approach" towards medicine and particularly towards patients.

Tumor-specific exon 1 mutations could be the ‘hit event’ predisposing Rb2/p130 gene to epigenetic silencing in lung cancer

Genetic alterations in Rb2/p130 gene have been reported in several tumors, but till now there are insufficient and conflicting data linking the loss of pRb2/p130 expression with the mutational status of this gene in lung cancer. We recently reported that loss or lowering of pRb2/p130 expression is mainly due to aberrant Rb2/p130 promoter methylation, in retinoblastoma tumors, and indicated that epigenetic silencing of Rb2/p130 can impair its function to negatively regulate cell cycle progression as well as apoptotic response. In order to clarify Rb2/p130 gene inactivation in lung cancer, we investigated whether epigenetic events could impair the expression of this gene in NSLC. Here, we show that specific Rb2-exon 1 homozygous mutations, occurring in an Rb2/p130, region, rich in CpG dinucleotides, could be the 'hit event' that predispose this gene to epigenetic changes, leading to Rb2/p130 gene silencing in lung cancer. Moreover, these homozygous mutations, found in different tumor histotypes, could represent tumor-specific markers.