RESUMO
Chemotherapy represents an important treatment option for colorectal cancer (CRC), but only half of the patients benefit from these regimens. We explored the potential predicting value and mechanism of PIK3CA mutation in CRC chemotherapy. CRC specimens from 440 patients were retrospectively collected and examined with a fluorescence PCR-based method. The correlation of first-line chemotherapy response and PIK3CA mutation was evaluated according to follow-up and medical records. The underlying mechanism of PIK3CA mutation in chemotherapy resistance was assessed with CRC tumors and primary cells. The mutation frequency of the PIK3CA gene in CRC patients was 9.55%, which was correlated with late TNM staging and lower histological grade. The CRC patients with PIK3A mutation showed worse response to first-line chemotherapy than those without PIK3CA mutation. PIK3A mutation tumor cells showed poor sensitivity to first-line chemotherapy in vitro and in vivo. PIK3CA mutation induced PI3K/Akt signaling activation to increase LGR5+ CRC stem cells survival and proliferation, from which lead to chemotherapy resistance. Furthermore, PIK3CA mutation/LGR5+ expression was an independent detrimental factor for CRC patients. Our findings indicated that PIK3CA mutation induced PI3K/Akt activation contributed to CRC stem cells survival and proliferation, from which cells further resistance to chemotherapy. PIK3CA mutation/LGR5+ expression was a potential biomarker for monitoring chemotherapy resistance in CRC.
Assuntos
Classe I de Fosfatidilinositol 3-Quinases/genética , Neoplasias Colorretais/genética , Adulto , Idoso , Idoso de 80 Anos ou mais , Sobrevivência Celular/efeitos dos fármacos , Cromonas/farmacologia , Classe I de Fosfatidilinositol 3-Quinases/metabolismo , Neoplasias Colorretais/tratamento farmacológico , Neoplasias Colorretais/metabolismo , Feminino , Fluoruracila/uso terapêutico , Células HCT116 , Humanos , Masculino , Pessoa de Meia-Idade , Morfolinas/farmacologia , Análise Multivariada , Mutação/genética , Fosforilcolina/análogos & derivados , Fosforilcolina/farmacologia , Receptores Acoplados a Proteínas G/genética , Receptores Acoplados a Proteínas G/metabolismo , Estudos RetrospectivosRESUMO
AIM: To explore the inhibitory effect of sulfated polysaccharide from Masson pine (Pinus massoniana) pollen (SPPM60) on G2/M phase of human liver cancer HepG2 cells and its mechanism. METHODS: The proliferation rate of HepG2 cells was evaluated by methyl thiazolyl tetrazolium (MTT) colorimetric assay. The cycles of HepG2 cells were measured by flow cytometry when 200µg/ml concentration of SPPM60 was adopted, the expression of the genes related to cell cycle was detected by real-time PCR. RESULTS: SPPM60 inhibited the proliferation of HepG2 cells and the inhibition rate was elevated with increase of SPPM60 concentration. After treatment with 200µg/ml of SPPM60, the percentage of S phase cells was decreased, but that of G2/M phase was significantly increased (72h vs control: 32.96±0.33% vs 18.59±0.04%, 3.44±0.05% vs 18.30±0.08%, P<0.01). The results of real-time PCR showed that SPPM60 could down-regulate the mRNA levels of CDK1 and CyclinB (P<0.01), and up-regulate the expression of p53 and p21 (P<0.05). CONCLUSION: SPPM60 causes arrest of HepG2 cells at G2/M phase, and the mechanism is related to the down-regulation of CDK1 and CyclinB and up-regulation of p53 and p21 expression.
