Background:The homologous recombination deficiency(HRD)score serves as a promising biomarker to iden-tify patients who are eligible for treatment with PARP inhibitors(PARPi).Previous studies have suggested a 3-biomark...Background:The homologous recombination deficiency(HRD)score serves as a promising biomarker to iden-tify patients who are eligible for treatment with PARP inhibitors(PARPi).Previous studies have suggested a 3-biomarker Genomic Instability Score(GIS)threshold of≥42 as a valid biomarker to predict response to PARPi in patients with ovarian cancer and breast cancer.However,the GIS threshold for prostate cancer(PCa)is still lacking.Here,we conducted an exploratory analysis to investigate an appropriate HRD score threshold and to evaluate its ability to predict response to PARPi in PCa patients.Methods:A total of 181 patients with metastatic castration-resistant PCa were included in this study.Tumor tissue specimens were collected for targeted next-generation sequencing for homologous recombination repair(HRR)genes and copy number variation(CNV)analysis.The HRD score was calculated based on over 50,000 single-nucleotide polymorphisms(SNP)distributed across the human genome,incorporating three SNP-based as-says:loss of heterozygosity,telomeric allelic imbalance,and large-scale state transition.The HRD score threshold was set at the last 5th percentile of the HRD scores in our cohort of known HRR-deficient tumors.The relation-ship between the HRD score and the efficacy in 16 patients of our cohort who received PARPi treatment were retrospectively analyzed.Results:Genomic testing was succeeded in 162 patients.In our cohort,61 patients(37.7%)had HRR mutations(HRRm).BRCA mutations occurred in 15 patients(9.3%).The median HRD score was 4(ranged from 0 to 57)in the total cohort,which is much lower than that in breast and ovarian cancers.Patients who harbored HRRm and BRCA or TP53 mutations had higher HRD scores.CNV occured more frequently in patients with HRRm.The last 5th percentile of HRD scores was 43 in the HRR-mutant cohort and consequently HRD high was defined as HRD scores≥43.In the 16 patients who received PARPi in our cohort,4 patients with a high HRD score achieved an objective response rate(ORR)of 100%while 12 patients with a low HRD score achieved an ORR of 8.3%.Progression-free survival(PFS)in HRD high patients was longer compared to HRD low patients,regardless of HRRm.Conclusions:A HRD score threshold of 43 was established and preliminarily validated to predict the efficacy of PARPi in this study.Future studies are needed to further verify this threshold.展开更多
PARP is an important protein in DNA repair pathways especially the base excision repair (BER). BER is involved in DNA repair of single strand breaks (SSBs). If BER is impaired, inhibiting poly(ADP-ribose) polymerase (...PARP is an important protein in DNA repair pathways especially the base excision repair (BER). BER is involved in DNA repair of single strand breaks (SSBs). If BER is impaired, inhibiting poly(ADP-ribose) polymerase (PARP), SSBs accumulate and become double stand breaks (DSBs). The cells with increasing number of DSBs become more dependent on other repair pathways, mainly the homologous recombination (HR) and the nonhomologous end joining. Patients with defective HR, like BRCA-deficient cell lines, are even more susceptible to impairment of the BER pathway. Inhibitors of PARP preferentially kill cancer cells in BRCA-mutation cancer cell lines over normal cells. Also, PARP inhibitors increase cytotoxicity by inhibiting repair in the presence of chemotherapies that induces SSBs. These two principles have been tested clinically. Over the last few years, excitement over this class of agents has escalated due to reported activity as single agent in BRCA1- or BRCA2-associated ovarian or breast cancers, and in combination with chemotherapy in triple negative breast cancer. This review covers the current results of clinical trials testing those two principles. It also evaluates future directions for the field of PARP inhibitor development.展开更多
Objective： Apoptosis is a reliable marker of chemotherapeutic efficacy. Olaparib and paclitaxel inhibit proliferation and induce apoptosis in a variety of cancers. We investigated the effects of paclitaxel combined w...Objective： Apoptosis is a reliable marker of chemotherapeutic efficacy. Olaparib and paclitaxel inhibit proliferation and induce apoptosis in a variety of cancers. We investigated the effects of paclitaxel combined with olaparib on apoptosis in breast cancer Bcap37 cells. Methods： Proliferation and apoptosis were detected by MTT assay and PI staining. Degradation of procaspase-3 and poly（ADP-ribose） polymerase （PARP） was analyzed by Western blotting. Results： Compared with paclitaxel alone, paclitaxel combined with 100 mg olaparib significantly reduced survival in Bcap37 cells at all tested treatment durations （P〈0.05）; inhibition increased with increasing olaparib dose and treatment time （P〈0.01）. Combined treatment yielded significantly higher rates of apoptosis （P〈0.05）, which also increased with time （P〈0.01）. Fluorescence micrographs showed that early and late apoptotic cells increased with treatment time. Pro-caspase-3 and PARP degradation was induced by paclitaxel and enhanced by olaparib in a dose-dependent manner. Thus, combined treatment was substantially more effective than treatment with paclitaxel alone. Conclusions： Our findings suggest that paclitaxel and olaparib inhibit breast cancer Bcap37 cell proliferation and induce apoptosis. Combined treatment further reduced cell growth and enhanced apoptosis, suggesting that this combination therapy may be a promising treaunent for breast cancer.展开更多
Objective:Fluzoparib(SHR3162)is a novel,potent poly(ADP-ribose)polymerases(PARP)1,2 inhibitor that showed anti-tumor activity in xenograft models.We conducted a phaseⅠ,first-in-human,dose-escalation and expansion(D-E...Objective:Fluzoparib(SHR3162)is a novel,potent poly(ADP-ribose)polymerases(PARP)1,2 inhibitor that showed anti-tumor activity in xenograft models.We conducted a phaseⅠ,first-in-human,dose-escalation and expansion(D-Esc and D-Ex)trial in patients with advanced solid cancer.Methods:This was a 3+3 phaseⅠD-Esc trial with a 3-level D-Ex at 5 hospitals in China.Eligible patients for DEsc had advanced solid tumors refractory to standard therapies,and D-Ex enrolled patients with ovarian cancer(OC).Fluzoparib was administered orally once or twice daily(bid)at 11 dose levels from 10 to 400 mg/d.Endpoints included dose-finding,safety,pharmacokinetics,and antitumor activity.Results:Seventy-nine patients were enrolled from March,2015 to January,2018[OC(47,59.5%);breast cancer(BC)(16,20.3%);colorectal cancer(8,10.1%),other tumors(8,10.1%)];48 patients were treated in the D-Esc arm and 31 in the D-Ex arm.The maximum tolerated dose(MTD)was 150 mg bid,with a half-life of 9.14 h.Grade 3/4 adverse events included anemia(7.6%)and neutropenia(5.1%).The objective response rate(ORR)was 30%(3/10)in patients with platinum-sensitive OC and 7.7%(1/13)in patients with BC.Among patients treated with fluzoparib≥120 mg/d,median progression-free survival(m PFS)was 7.2[95%confidence interval(95%CI),1.8-9.3]months in OC,9.3(95%CI,7.2-9.3)months in platinum-sensitive OC,and 3.5(range,2.0-28.0)months in BC.In patients with germline BC susceptibility gene mutation(g BRCAMut)(11/43 OC;2/16 BC),m PFS was 8.9 months for OC(range,1.0-23.2;95%CI,1.0-16.8)and 14 and 28 months for BC(those two patients both also had somatic BRCAMut).Conclusions:The MTD of fluzoparib was 150 mg bid in advanced solid malignancies.Fluzoparib demonstrated single-agent antitumor activity in BC and OC,particularly in BRCAMut and platinum-sensitive OC.展开更多
Objective:The newly defined cancer-testis(CT)gene,MEIOB,was previously found to play key roles in DNA double-strand break(DSB)repair.In this study,we aimed to investigate the effects and mechanisms of MEIOB in the car...Objective:The newly defined cancer-testis(CT)gene,MEIOB,was previously found to play key roles in DNA double-strand break(DSB)repair.In this study,we aimed to investigate the effects and mechanisms of MEIOB in the carcinogenesis of triple-negative breast cancers(TNBCs).Methods:The Cancer Genome Atlas database was used to quantify the expression of MEIOB.Cox regression analysis was used to evaluate the association between MEIOB expression and the prognosis of human TNBC.The effects of MEIOB on cell proliferation and migration in TNBCs were also assessed in vitro.Patient-derived xenograft(PDX)models were used to assess the sensitivity of breast cancers with active MEIOB to PARP1 inhibitors.Results:We confirmed MEIOB as a CT gene whose expression was restricted to the testes and breast tumors,especially TNBCs.Its activation was significantly associated with poor survival in breast cancer patients[overall,hazard ratio(HR)=1.90(1.16–2.06);TNBCs:HR=7.05(1.16–41.80)].In addition,we found that MEIOB was oncogenic and significantly promoted the proliferation of TNBC cells.Further analysis showed that MEIOB participated in DSB repair in TNBCs.However,in contrast to its function in meiosis,it mediated homologous recombination deficiency(HRD)through the activation of poly ADP-ribose polymerase(PARP)1 by interacting with YBX1.Furthermore,activated MEIOB was shown to confer sensitivity to PARP inhibitors,which was confirmed in PDX models.Conclusions:MEIOB played an oncogenic role in TNBC through its involvement in HRD.In addition,dysregulation of MEIOB sensitized TNBC cells to PARP inhibitors,so MEIOB may be a therapeutic target of PARP1 inhibitors in TNBC.展开更多
A novel treatment for cancer patients with homozygous deletions of BRCA1 and BRCA2 is to use drugs that inhibit the enzyme poly(ADP-ribose) polymerase (PARP). Specific inhibition of PARP-1 can induce synthetic lethali...A novel treatment for cancer patients with homozygous deletions of BRCA1 and BRCA2 is to use drugs that inhibit the enzyme poly(ADP-ribose) polymerase (PARP). Specific inhibition of PARP-1 can induce synthetic lethality in irradiated cancer cells while theoretically leaving normal tissue unaffected. We recently demonstrated in a cell survival assay that lymphoblastoid cells with mono-allelic mutations of BRCA1 were hypersensitive to gamma radiation in the presence of the PARP-1 inhibitor Olaparib compared to normal cells and mono-allelic BRCA2 cells. To determine if the enhanced radiation sensitivity was due to a persistence of DNA strand breaks, we performed γ-H2AX foci analysis in cells derived from two normal individuals, three heterozygous BRCA1 and three heterozygous BRCA2 cell lines. Cells were exposed to 2 Gy gamma radiation in the presence or absence of 5 μM Olaparib. Using immunofluorescence and imaging flow cytometry, foci were measured in untreated cells and at 0.5, 3, 5 and 24 hours post-irradiation. In all lymphoblastoid cells treated with 2 Gy gamma radiation, there was a predictable induction of DNA strand breaks, with a modest but significant retention of foci over 24 hours in irradiated cells treated with Olaparib (ANOVA P < 0.05). However, in mono-allelic BRCA1 cells, there was a failure to fully repair DNA double-strand breaks (DSB) in the presence of Olaparib, evidenced by a significant retention of foci at 24 hours’ post irradiation (t-Test P These data show that the cellular hypersensitivity of mono-allelic BRCA1 lymphoblastoid cells to gamma radiation in the presence of the Olaparib is due to the retention of DNA DSB. These data may indicate that patients with inherited mutations in the BRCA1 gene treated with radiotherapy and PARP-1 inhibitors may experience elevated radiation-associated normal tissue toxicity.展开更多
Pancreatic cancer is one of the most aggressive cancers with a median survival time of less than 5 months,and conventional chemotherapeutics are the main treatment strategy.Poly(ADP-ribose)polymerase(PARP)inhibitors h...Pancreatic cancer is one of the most aggressive cancers with a median survival time of less than 5 months,and conventional chemotherapeutics are the main treatment strategy.Poly(ADP-ribose)polymerase(PARP)inhibitors have been recently approved for BRCA1/2-mutant pancreatic cancer,opening a new era for targeted therapy for this disease.However,most pancreatic cancer patients carry wild-type BRCA1/2 with resistance to PARP inhibitors.Here,we reported that mammalian target of rapamycin complex 2(mTORC2)kinase is overexpressed in pancreatic cancer tissues and promotes pancreatic cancer cell growth and invasion.Moreover,we found that knockdown of the mTORC2 obligate subunit Rictor sensitized pancreatic cancer cells to the PARP inhibitor olaparib.Mechanistically,we showed that mTORC2 positively regulates homologous recombination(HR)repair by modulating BRCA1 recruitment to DNA double-strand breaks(DSBs).In addition,we confirmed that combination treatment with the mTORC2 inhibitor PP242 and the PARP inhibitor olaparib synergistically inhibited pancreatic cancer growth in vivo.Thus,this study provides a novel target and strategy for optimizing PARP inhibitor efficiency in pancreatic cancers.展开更多
Ionizing radiation is frequently used to treat solid tumors,as it causes DNA damage and kill cancer cells.However,damaged DNA is repaired involving poly-(ADP-ribose)polymerase-1(PARP-1)causing resistance to radiation ...Ionizing radiation is frequently used to treat solid tumors,as it causes DNA damage and kill cancer cells.However,damaged DNA is repaired involving poly-(ADP-ribose)polymerase-1(PARP-1)causing resistance to radiation therapy.Thus,PARP-1 represents an important target in multiple cancer types,including prostate cancer.PARP is a nuclear enzyme essential for single-strand DNA breaks repair.Inhibiting PARP-1 is lethal in a wide range of cancer cells that lack the homologous recombination repair(HR)pathway.This article provides a concise and simplified overview of the development of PARP inhibitors in the laboratory and their clinical applications.We focused on the use of PARP inhibitors in various cancers,including prostate cancer.We also discussed some of the underlying principles and challenges that may affect the clinical efficacy of PARP inhibitors.展开更多
基金supported by the National Natural Science Foundation of China(grant number:82303223)the Basic and Applied Basic Research Foundation of Guangdong Province(grant numbers:2021A1515220064,2022A1515110299)the Medical Scientific Re-search Foundation of Guangdong Province(grant number:A2022492).
文摘Background:The homologous recombination deficiency(HRD)score serves as a promising biomarker to iden-tify patients who are eligible for treatment with PARP inhibitors(PARPi).Previous studies have suggested a 3-biomarker Genomic Instability Score(GIS)threshold of≥42 as a valid biomarker to predict response to PARPi in patients with ovarian cancer and breast cancer.However,the GIS threshold for prostate cancer(PCa)is still lacking.Here,we conducted an exploratory analysis to investigate an appropriate HRD score threshold and to evaluate its ability to predict response to PARPi in PCa patients.Methods:A total of 181 patients with metastatic castration-resistant PCa were included in this study.Tumor tissue specimens were collected for targeted next-generation sequencing for homologous recombination repair(HRR)genes and copy number variation(CNV)analysis.The HRD score was calculated based on over 50,000 single-nucleotide polymorphisms(SNP)distributed across the human genome,incorporating three SNP-based as-says:loss of heterozygosity,telomeric allelic imbalance,and large-scale state transition.The HRD score threshold was set at the last 5th percentile of the HRD scores in our cohort of known HRR-deficient tumors.The relation-ship between the HRD score and the efficacy in 16 patients of our cohort who received PARPi treatment were retrospectively analyzed.Results:Genomic testing was succeeded in 162 patients.In our cohort,61 patients(37.7%)had HRR mutations(HRRm).BRCA mutations occurred in 15 patients(9.3%).The median HRD score was 4(ranged from 0 to 57)in the total cohort,which is much lower than that in breast and ovarian cancers.Patients who harbored HRRm and BRCA or TP53 mutations had higher HRD scores.CNV occured more frequently in patients with HRRm.The last 5th percentile of HRD scores was 43 in the HRR-mutant cohort and consequently HRD high was defined as HRD scores≥43.In the 16 patients who received PARPi in our cohort,4 patients with a high HRD score achieved an objective response rate(ORR)of 100%while 12 patients with a low HRD score achieved an ORR of 8.3%.Progression-free survival(PFS)in HRD high patients was longer compared to HRD low patients,regardless of HRRm.Conclusions:A HRD score threshold of 43 was established and preliminarily validated to predict the efficacy of PARPi in this study.Future studies are needed to further verify this threshold.
文摘PARP is an important protein in DNA repair pathways especially the base excision repair (BER). BER is involved in DNA repair of single strand breaks (SSBs). If BER is impaired, inhibiting poly(ADP-ribose) polymerase (PARP), SSBs accumulate and become double stand breaks (DSBs). The cells with increasing number of DSBs become more dependent on other repair pathways, mainly the homologous recombination (HR) and the nonhomologous end joining. Patients with defective HR, like BRCA-deficient cell lines, are even more susceptible to impairment of the BER pathway. Inhibitors of PARP preferentially kill cancer cells in BRCA-mutation cancer cell lines over normal cells. Also, PARP inhibitors increase cytotoxicity by inhibiting repair in the presence of chemotherapies that induces SSBs. These two principles have been tested clinically. Over the last few years, excitement over this class of agents has escalated due to reported activity as single agent in BRCA1- or BRCA2-associated ovarian or breast cancers, and in combination with chemotherapy in triple negative breast cancer. This review covers the current results of clinical trials testing those two principles. It also evaluates future directions for the field of PARP inhibitor development.
文摘Objective： Apoptosis is a reliable marker of chemotherapeutic efficacy. Olaparib and paclitaxel inhibit proliferation and induce apoptosis in a variety of cancers. We investigated the effects of paclitaxel combined with olaparib on apoptosis in breast cancer Bcap37 cells. Methods： Proliferation and apoptosis were detected by MTT assay and PI staining. Degradation of procaspase-3 and poly（ADP-ribose） polymerase （PARP） was analyzed by Western blotting. Results： Compared with paclitaxel alone, paclitaxel combined with 100 mg olaparib significantly reduced survival in Bcap37 cells at all tested treatment durations （P〈0.05）; inhibition increased with increasing olaparib dose and treatment time （P〈0.01）. Combined treatment yielded significantly higher rates of apoptosis （P〈0.05）, which also increased with time （P〈0.01）. Fluorescence micrographs showed that early and late apoptotic cells increased with treatment time. Pro-caspase-3 and PARP degradation was induced by paclitaxel and enhanced by olaparib in a dose-dependent manner. Thus, combined treatment was substantially more effective than treatment with paclitaxel alone. Conclusions： Our findings suggest that paclitaxel and olaparib inhibit breast cancer Bcap37 cell proliferation and induce apoptosis. Combined treatment further reduced cell growth and enhanced apoptosis, suggesting that this combination therapy may be a promising treaunent for breast cancer.
文摘Objective:Fluzoparib(SHR3162)is a novel,potent poly(ADP-ribose)polymerases(PARP)1,2 inhibitor that showed anti-tumor activity in xenograft models.We conducted a phaseⅠ,first-in-human,dose-escalation and expansion(D-Esc and D-Ex)trial in patients with advanced solid cancer.Methods:This was a 3+3 phaseⅠD-Esc trial with a 3-level D-Ex at 5 hospitals in China.Eligible patients for DEsc had advanced solid tumors refractory to standard therapies,and D-Ex enrolled patients with ovarian cancer(OC).Fluzoparib was administered orally once or twice daily(bid)at 11 dose levels from 10 to 400 mg/d.Endpoints included dose-finding,safety,pharmacokinetics,and antitumor activity.Results:Seventy-nine patients were enrolled from March,2015 to January,2018[OC(47,59.5%);breast cancer(BC)(16,20.3%);colorectal cancer(8,10.1%),other tumors(8,10.1%)];48 patients were treated in the D-Esc arm and 31 in the D-Ex arm.The maximum tolerated dose(MTD)was 150 mg bid,with a half-life of 9.14 h.Grade 3/4 adverse events included anemia(7.6%)and neutropenia(5.1%).The objective response rate(ORR)was 30%(3/10)in patients with platinum-sensitive OC and 7.7%(1/13)in patients with BC.Among patients treated with fluzoparib≥120 mg/d,median progression-free survival(m PFS)was 7.2[95%confidence interval(95%CI),1.8-9.3]months in OC,9.3(95%CI,7.2-9.3)months in platinum-sensitive OC,and 3.5(range,2.0-28.0)months in BC.In patients with germline BC susceptibility gene mutation(g BRCAMut)(11/43 OC;2/16 BC),m PFS was 8.9 months for OC(range,1.0-23.2;95%CI,1.0-16.8)and 14 and 28 months for BC(those two patients both also had somatic BRCAMut).Conclusions:The MTD of fluzoparib was 150 mg bid in advanced solid malignancies.Fluzoparib demonstrated single-agent antitumor activity in BC and OC,particularly in BRCAMut and platinum-sensitive OC.
基金supported by the National Natural Science Foundation of China(Grant Nos.81902836 and 81572602)the China Postdoctoral Science Foundation(Grant Nos.2017M610339 and 2018M630584)。
文摘Objective:The newly defined cancer-testis(CT)gene,MEIOB,was previously found to play key roles in DNA double-strand break(DSB)repair.In this study,we aimed to investigate the effects and mechanisms of MEIOB in the carcinogenesis of triple-negative breast cancers(TNBCs).Methods:The Cancer Genome Atlas database was used to quantify the expression of MEIOB.Cox regression analysis was used to evaluate the association between MEIOB expression and the prognosis of human TNBC.The effects of MEIOB on cell proliferation and migration in TNBCs were also assessed in vitro.Patient-derived xenograft(PDX)models were used to assess the sensitivity of breast cancers with active MEIOB to PARP1 inhibitors.Results:We confirmed MEIOB as a CT gene whose expression was restricted to the testes and breast tumors,especially TNBCs.Its activation was significantly associated with poor survival in breast cancer patients[overall,hazard ratio(HR)=1.90(1.16–2.06);TNBCs:HR=7.05(1.16–41.80)].In addition,we found that MEIOB was oncogenic and significantly promoted the proliferation of TNBC cells.Further analysis showed that MEIOB participated in DSB repair in TNBCs.However,in contrast to its function in meiosis,it mediated homologous recombination deficiency(HRD)through the activation of poly ADP-ribose polymerase(PARP)1 by interacting with YBX1.Furthermore,activated MEIOB was shown to confer sensitivity to PARP inhibitors,which was confirmed in PDX models.Conclusions:MEIOB played an oncogenic role in TNBC through its involvement in HRD.In addition,dysregulation of MEIOB sensitized TNBC cells to PARP inhibitors,so MEIOB may be a therapeutic target of PARP1 inhibitors in TNBC.
文摘A novel treatment for cancer patients with homozygous deletions of BRCA1 and BRCA2 is to use drugs that inhibit the enzyme poly(ADP-ribose) polymerase (PARP). Specific inhibition of PARP-1 can induce synthetic lethality in irradiated cancer cells while theoretically leaving normal tissue unaffected. We recently demonstrated in a cell survival assay that lymphoblastoid cells with mono-allelic mutations of BRCA1 were hypersensitive to gamma radiation in the presence of the PARP-1 inhibitor Olaparib compared to normal cells and mono-allelic BRCA2 cells. To determine if the enhanced radiation sensitivity was due to a persistence of DNA strand breaks, we performed γ-H2AX foci analysis in cells derived from two normal individuals, three heterozygous BRCA1 and three heterozygous BRCA2 cell lines. Cells were exposed to 2 Gy gamma radiation in the presence or absence of 5 μM Olaparib. Using immunofluorescence and imaging flow cytometry, foci were measured in untreated cells and at 0.5, 3, 5 and 24 hours post-irradiation. In all lymphoblastoid cells treated with 2 Gy gamma radiation, there was a predictable induction of DNA strand breaks, with a modest but significant retention of foci over 24 hours in irradiated cells treated with Olaparib (ANOVA P < 0.05). However, in mono-allelic BRCA1 cells, there was a failure to fully repair DNA double-strand breaks (DSB) in the presence of Olaparib, evidenced by a significant retention of foci at 24 hours’ post irradiation (t-Test P These data show that the cellular hypersensitivity of mono-allelic BRCA1 lymphoblastoid cells to gamma radiation in the presence of the Olaparib is due to the retention of DNA DSB. These data may indicate that patients with inherited mutations in the BRCA1 gene treated with radiotherapy and PARP-1 inhibitors may experience elevated radiation-associated normal tissue toxicity.
基金This work was supported by the National Natural Science Foundation of China(81572408)the Program of Medical Innovation Team and Leading Medical Talents in Jiangsu Province(2017ZXKJQW09).
文摘Pancreatic cancer is one of the most aggressive cancers with a median survival time of less than 5 months,and conventional chemotherapeutics are the main treatment strategy.Poly(ADP-ribose)polymerase(PARP)inhibitors have been recently approved for BRCA1/2-mutant pancreatic cancer,opening a new era for targeted therapy for this disease.However,most pancreatic cancer patients carry wild-type BRCA1/2 with resistance to PARP inhibitors.Here,we reported that mammalian target of rapamycin complex 2(mTORC2)kinase is overexpressed in pancreatic cancer tissues and promotes pancreatic cancer cell growth and invasion.Moreover,we found that knockdown of the mTORC2 obligate subunit Rictor sensitized pancreatic cancer cells to the PARP inhibitor olaparib.Mechanistically,we showed that mTORC2 positively regulates homologous recombination(HR)repair by modulating BRCA1 recruitment to DNA double-strand breaks(DSBs).In addition,we confirmed that combination treatment with the mTORC2 inhibitor PP242 and the PARP inhibitor olaparib synergistically inhibited pancreatic cancer growth in vivo.Thus,this study provides a novel target and strategy for optimizing PARP inhibitor efficiency in pancreatic cancers.
文摘Ionizing radiation is frequently used to treat solid tumors,as it causes DNA damage and kill cancer cells.However,damaged DNA is repaired involving poly-(ADP-ribose)polymerase-1(PARP-1)causing resistance to radiation therapy.Thus,PARP-1 represents an important target in multiple cancer types,including prostate cancer.PARP is a nuclear enzyme essential for single-strand DNA breaks repair.Inhibiting PARP-1 is lethal in a wide range of cancer cells that lack the homologous recombination repair(HR)pathway.This article provides a concise and simplified overview of the development of PARP inhibitors in the laboratory and their clinical applications.We focused on the use of PARP inhibitors in various cancers,including prostate cancer.We also discussed some of the underlying principles and challenges that may affect the clinical efficacy of PARP inhibitors.
