Project description:The PIK3CA-related overgrowth syndrome (PROS) patient-derived induced pluripotent stem cell (iPSC) lines M98-WT and M98-E418K were obtained from a female, 18-y-old PROS patient by episomal reprogramming of a dermal fibroblast culture with 32% mosaicism for PIK3CA-E418K heterozygosity. All clones used for experimental studies were confirmed transgene-free and expressed high levels of pluripotent stem cell-specific markers, comparable to those of a reference hPSC line. Karyotyping on a single line from each genotype confirmed lack of microscopic genetic rearrangements. The original patient-derived dermal fibroblasts were obtained with full informed consent in accord with the Declaration of Helsinki. The study was approved by The Cambridge South Ethics.
Project description:PIK3CA-related overgrowth syndromes (PROS) are caused by somatic variants that result in constitutive activation of the phosphatidylinositol-3-kinase/AKT/mTOR pathway. Promising responses to molecularly targeted therapy have been reported, however identification of an appropriate agent can be hampered by the mosaic nature and low variant allele frequency of the causal variant. Moreover, our understanding of the molecular repercussions of these variants at the single cell level remain limited. Here we report in vitro expansion of affected tissue followed by exome sequencing and combined 3’ whole transcriptome and targeted long-read single cell RNA-sequencing in a patient with clinical symptoms consistent with Megalencephaly-Capillary Malformation Syndrome (MCAP, a PROS condition). This approach identified a targetable PIK3CA variant restricted to a PAX3+ fibroblast population. These studies highlight the utility of novel next-generation sequencing strategies in the management of suspected syndromes of somatic mosaicism and provide insight into the underlying pathophysiology of a debilitating genetic syndrome.
Project description:The aim is to investigate expression patterns of 69 primary tumor samples related to mutation status of FGFR2, KRAS and PIK3CA, and clinico-pathological data.
Project description:Mutant PIK3CA and Her2 genes are oncogenic and their co-existence in breast cancer has been well identified. However, the gene targets and cell signalling pathway regulated by mutant PIK3CA, Her2 and both of PIK3CA and Her2 have not been well studied. We established stable cell models through transfecting mutant PIK3CA, Her2 and both mutant PIK3CA and Her2 into MCF10A cells and performed Affymetrix microarray to identify downstream target genes controlled by either mutant PIK3CA, Her2 or both PIK3CA and Her2.
Project description:MCF10A cells: control vs. PIK3CA mutant (H1047R) Transcriptional profiling of MCF10A comparing control (expressing JP1520-PIK3CA-WT; Addgen plasmid #14570) and PIK3CA mutant (JP1520-PIK3CA-H1047R; Addgene plasmic#14572). Goal was to determine the effects of the PIK3CA H1047R mutation in the on global gene expression in MCF10A cells.
Project description:Purpose: Cerebral cavernous malformations (CCMs) are hemorrhagic neurovascular malformations that may lead to stroke, seizures and other clinical sequelae. Recent studies have shown that somatic mutations in MAP3K3 and PIK3CA also contribute to CCM pathogenesis; however, it remains unclear how these mutations contribute to sporadic versus familial cases. In our previous research, we’ve shown that co-occurring MAP3K3 and PIK3CA mutations are present within the same clonal population of cells. The overall goal of this study was to identify PIK3CA mutations in CCM-associated developmental venous anomalies (DVA). We also analyzed the plasma miRNome of patients with (1) DVA without associated CCM, as well as (2) DVA with an associated CCM) to identify circulating miRNAs that might serve as biomarkers reflecting PIK3CA activity. Methods: We collected and sequenced the plasma miRNome of 12 individuals with a sporadic CCM associated with a DVA (CCM + DVA), 6 individuals with a DVA without a CCM (DVA only), and 7 healthy controls. Results: We found that the identical PIK3CA mutation is found in endothelial cells of both the DVA and its associated CCM, but that an activating MAP3K3 mutation appears only in the CCM. The analyses miR-134-5p was downregulated in the groups of patients with only a DVA only group (when compared to healthy controls). This miRNA has been shown to target PIK3CA. In addition, miR-182-5p, was upregulated and targets MAP3K3; while let-7c-5p was downregulated and targets both PIK3CA and MAP3K3 in the group of patients with CCM and an associated DVA (when compared to DVA only). Conclusions: These results support a mechanism where DVA develop as the result of a PIK3CA mutation, creating a region of the brain vasculature that functions as a genetic primer for CCM development following acquisition of an additional somatic mutation.
Project description:The CHER-LOB randomized phase II study showed that the combination of lapatinib and trastuzumab plus chemotherapy increases the pathologic complete remission (pCR) rate as compared to chemotherapy plus either trastuzumab or lapatinib. An extensive biomarker programme was prospectively planned to identify potential predictors of sensitivity to different treatments and evaluate treatment effect on tumor biomarkers. A mutation in PIK3CA exon 20 or 9 was documented in 20% of the cases. Overall, the pCR rates were similar in PIK3CA wild type and PIK3CA mutated patients (33.3% vs 22.7%; p=0.323). However, for patients receiving trastuzumab plus lapatinib, the probability of pCR was higher in PIK3CA wild type tumors (48.4% vs 12.5%; p=0.06). Ki67, pAKT and apoptosis measured on the residual disease were significantly reduced from baseline. The degree of Ki67 inhibition was significantly higher in patients receiving the dual anti-HER2 blockade. In conclusion, PIK3CA mutations seem to identify patients less likely to benefit from dual anti-HER2 inhibition. p95-HER2 and markers of PI3K pathway deregulation are not confirmed as markers of different sensitivity to trastuzumab or lapatinib.
Project description:HER2 (ERBB2) gene amplification and PIK3CA mutations often co-occur in breast cancer, and aberrant activation of the PI3K pathway has been implicated in resistance to HER2-directed therapies. We have created a mouse model of HER2-overexpressing (HER2+), PIK3CAH1047R-mutant breast cancer. Mice expressing both human HER2 and mutant PIK3CA in their mammary glands developed tumors with a significantly shorter latency compared to mice expressing either oncogene alone. By microarray analysis, HER2-driven tumors clustered with the luminal subtype, whereas HER2+PIK3CA and PIK3CA-driven tumors were associated with the claudin-low breast cancer subtype. In accordance, PIK3CA and HER2+PIK3CA tumors expressed elevated levels of EMT and stem cell markers, and cells from HER2+PIK3CA tumors more efficiently formed mammospheres, providing further evidence that activated PIK3CA may enrich for cancer stem cells. Finally, HER2+PIK3CA tumors are resistant to the HER2 antibody trastuzumab; resistance is partially reversed by the addition of a PI3K inhibitor. Taken together, these studies suggest that the co-expression of HER2 and PI3KH1047R in the mouse mammary gland accelerates the formation of aggressive, trastuzumab-resistant tumors. referenceXsample