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S. Nicholson
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MA02 - RNA in Lung Cancer (ID 377)
- Event: WCLC 2016
- Type: Mini Oral Session
- Track: Biology/Pathology
- Presentations: 1
- Moderators:E. Brambilla, M. Noguchi
- Coordinates: 12/05/2016, 14:20 - 15:50, Stolz 2
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MA02.02 - A Novel 5-miR Signature Shows Promise as a Diagnostic Tool and as a Predictor of Cisplatin Response in NSCLC (ID 5948)
14:26 - 14:32 | Author(s): S. Nicholson
- Abstract
Background:
MicroRNAs are a class of small non-coding RNAs that range in size from 19-25 nucleotides. They have been shown to regulate a number of processes within tumour biology, including metastasis, invasion and angiogenesis. More recently, miRNAs have been linked to chemoresistance in solid tumours, including lung cancer.
Methods:
MicroRNA expression within an isogenic panel of age-matched parent (PT) and cisplatin resistant (CisR) NSCLC cell lines was profiled using the 7[th] generation miRCURY LNA arrays (Exiqon). Significantly altered miRNAs within the CisR sublines were manipulated using antagomirs (Exiqon) and Pre-miRs (Ambion) and functional studies were carried out in the presence and absence of cisplatin. To examine the translational relevance of these miRNAs, their expression was examined in a cohort of chemo-naïve patient-matched normal and lung tumour tissue and serum from NSCLC patients of different histologies. To create a xenograft model of cisplatin resistance 1x10[3 ]cells H460 PT or CisR cells were injected into 5-7week old NOD/SCID mice. Tumour volume was measured over time and harvested once the tumour mass measured 500mm[3] and formalin-fixed and paraffin embedded (FFPE). Expression of the 5-miR signature was analysed within FFPE murine tumours and cisplatin resistance was investigated relative to cisplatin sensitive controls.
Results:
Profiling and subsequent validation revealed a 5-miR signature associated with our model of cisplatin resistance (miR-30a-3p, miR-30b-5p, miR-30c-5p, miR-34a-5p, miR-4286). Inhibition of the miR-30 family and miR-34a-5p reduced clonogenic survival of CisR cells when treated cisplatin. Expression of the miRNA signature was significantly altered in both adenocarcinoma (AD) and squamous cell carcinoma (SCC) relative to matched normal lung tissue and between SCC and AD tissue. miR-4286 was significantly up-regulated in SCC sera compared to normal control and AD sera. Similarly to the cell line expression of the miRNAs, the miR-30 family members and miR-34a-5p were up-regulated in the CisR xenograft FFPE tissue relative to PT.
Conclusion:
A novel miRNA signature associated with cisplatin resistance was identified in vitro, genetic manipulation of which altered clonogenic response to cisplatin. The 5-miR signature shows both diagnostic and prognostic biomarker potential across a number of diagnostically relevant biological mediums.
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P2.03a - Poster Session with Presenters Present (ID 464)
- Event: WCLC 2016
- Type: Poster Presenters Present
- Track: Advanced NSCLC
- Presentations: 1
- Moderators:
- Coordinates: 12/06/2016, 14:30 - 15:45, Hall B (Poster Area)
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P2.03a-062 - Characterisation and Targeting of the DNA Repair Gene, XRCC6BP1, in Cisplatin Resistant NSCLC (ID 5198)
14:30 - 14:30 | Author(s): S. Nicholson
- Abstract
Background:
In the absence of specific treatable mutations, platinum-based doublet chemotherapy remains the gold standard treatment for NSCLC patients. However, its clinical efficacy is hindered in many patients due to intrinsic and acquired resistance to these agents, in particular cisplatin. Alterations in the DNA repair capacity of damaged cells is now recognised as an important factor in mediating this phenomenon.
Methods:
DNA Repair Pathway RT[2 ]Profiler Arrays were used to elucidate key DNA repair genes implicated in chemoresistant NSCLC cells using cisplatin resistant (CisR) and corresponding parental (PT) H460 cells previously established in our laboratory. DNA repair genes significantly altered in CisR cells were validated at the mRNA and protein level, using RT-PCR and Western blot analysis, respectively. The translational relevance of differentially expressed genes was examined in a cohort of chemo-naïve matched normal and tumour lung tissues from NSCLC patients. Loss of function studies were carried out using siRNA technology. The effect of XRCC6BP1 gene knockdown on apoptosis was assessed by FACS using Annexin-V/PI staining. Cellular expression and localisation of XRCC6BP1 protein and γH2AX foci in response to cisplatin were examined by immunofluorescence using the Cytell™ Imaging System. To investigate a role for XRCC6BP1 in lung cancer stem cells, Side Population (SP) studies were used to characterise stem-like cells in chemoresistant cells. XRCC6BP1 mRNA analysis was also examined in ALDH1[+] and ALDH1[- ]subpopulations.
Results:
We identified a number of critical DNA repair genes that were differentially regulated between H460 PT and CisR NSCLC cells, where XRCC6BP1 mRNA and protein expression was significantly increased (mRNA; 19.4-fold) in H460 CisR cells relative to their PT counterparts. Relative to matched normal lung tissues, XRCC6BP1 mRNA was significantly increased in lung adenocarcinoma patients. Gene silencing of XRCC6BP1 induced significant apoptosis of CisR cells and reduced the DNA repair capacity of these cells relative to scrambled (negative) controls. Immunofluorescence studies showed an increase in XRCC6BP1 protein expression and γH2AX foci in CisR cells relative to their PT counterparts. SP analysis revealed a significantly higher stem cell population in CisR cells, while XRCC6BP1 mRNA expression was considerably increased in SKMES-1, H460 and H1299 ALDH1[+] CisR cells compared to ALDH1[-] cells.
Conclusion:
We identified XRCC6BP1 as key DNA repair gene implicated in cisplatin resistant NSCLC. Our data highlight the potential of targeting components of the DNA repair pathway in chemoresistant lung cancer, in particular, XRCC6BP1, either alone or in combination with conventional cytotoxic therapies.
