Neoadjuvant chemotherapy for gastric cancer: what are we trying to accomplish?

Ethaselen synergizes with oxaliplatin in tumor growth inhibition by inducing ROS production and inhibiting TrxR1 activity in gastric cancer

Background

Oxaliplatin is one of the most commonly used chemotherapeutic agent for the treatment of various cancers, including gastric cancer. It has, however, a narrow therapeutic index due to its toxicity and the occurrence of drug resistance. Hence, it is of great significance to develop novel therapies to potentiate the anti-tumor effect and reduce the toxicity of oxaliplatin. In our previous study, we demonstrated that ethaselen (BBSKE), an inhibitor of thioredoxin reductase, effectively inhibited the growth of gastric cancer cells and promoted apoptosis in vitro. In the present study, we investigated whether BBSKE can potentiate the anti-tumor effect of oxaliplatin in gastric cancer in vivo and vitro.

Methods

Cellular apoptosis and ROS levels were analyzed by flow cytometry. Thioredoxin reductase 1 (TrxR1) activity in gastric cancer cells, organoid and tumor tissues was determined by using the endpoint insulin reduction assay. Western blot was used to analyze the expressions of the indicated proteins. Nude mice xenograft models were used to test the effects of BBSKE and oxaliplatin combinations on gastric cancer cell growth in vivo. In addition, we also used the combined treatment of BBSKE and oxaliplatin in three cases of gastric cancer Patient-Derived organoid (GC-PDO) to detect the anti-tumor effect.

Results

We found that BBSKE significantly enhanced oxaliplatin-induced growth inhibition in gastric cancer cells by inhibiting TrxR1 activity. Because of the inhibition of TrxR1 activity, BBSKE synergized with oxaliplatin to enhance the production of ROS and activate p38 and JNK signaling pathways which eventually induced apoptosis of gastric cancer cells. In vivo, we also found that BBSKE synergized with oxaliplatin to suppress the gastric cancer tumor growth in xenograft nude mice model, accompanied by the reduced TrxR1 activity. Remarkably, we found that BBSKE attenuated body weight loss evoked by oxaliplatin treatment. We also used three cases of GC-PDO and found that the combined treatment of BBSKE and oxaliplatin dramatically inhibited the growth and viability of GC-PDO with increased ROS level, decreased TrxR1 activity and enhanced apoptosis.

Conclusions

This study elucidates the underlying mechanisms of synergistic effect of BBSKE and oxaliplatin, and suggests that the combined treatment has potential value in gastric cancer therapy.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13046-021-02052-z.

PolG Inhibits Gastric Cancer Glycolysis and Viability by Suppressing PKM2 Phosphorylation

Purpose

Gastric cancer (GC) is the fifth most frequently diagnosed cancer and the third leading cause of cancer-related death. There is a critical need for the development of novel therapies in GC. DNA polymerase gamma (PolG) has been implicated in mitochondrial homeostasis and affects the development of numerous types of cancer, however, its effects on GC and molecular mechanisms remain to be fully determined. The aim of the present research was to clarify the effects of PolG on GC and its possible molecular mechanism of action.

Methods

The GSE62254 dataset was used to predict the effect of PolG on prognostic value in GC patients. Lentivirus-mediated transduction was used to silence PolG expression. Western blot analysis evinced the silencing effect. Co-immunoprecipitation (Co-IP) analysis was performed to explore the potential molecular mechanism of action. Analysis of the glycolysis process in GC cells was also undertaken. Cell proliferation was determined using a CCK-8 (Cell Counting Kit-8) proliferation assay. Cell migration was detected using the Transwell device. Animal experiments were used to measure in vivo xenograft tumor growth.

Results

GC patients with low PolG expression have worse overall survival (OS) and progression-free survival (PFS). PolG binds to PKM2 and affects the activation of Tyr105-site phosphorylation, thus interfering with the glycolysis of GC cells. In vitro tumor formation experiments in mice also confirmed that PolG silencing of GC has a stronger proliferation ability. PolG can suppress GC cell growth both in vivo and in vitro.

Conclusion

Our study reveals a potential molecular mechanism between PolG and the energy metabolic process of GC tumor cells for the first time, suggesting PolG as an independent novel potential therapeutic target for tumor therapy, and providing new ideas for clinical GC treatment.

Preoperative N stage evaluation in advanced gastric cancer patients using multidetector CT: can the sum of the diameters of metastatic LNs be used for N stage evaluation?

AIM

To compare the diagnostic performance of total counts of metastatic lymph nodes (LN-sum) and conventional multidetector (MD) computed tomography (CT) staging in the nodal evaluation of advanced gastric cancer (AGC) patients.

MATERIALS AND METHODS

In total, 127 consecutive patients who underwent preoperative MDCT and gastrectomy for AGC were identified. Metastatic LNs on MDCT were defined as LNs with a short axis ≥8 mm, marked or heterogeneous enhancement, and morphological features (central necrosis, round shape, clustering). The sensitivity, specificity, accuracy, positive predictive value (PPV), and negative predictive value (NPV) of the N-stage using LN-sum and conventional MDCT staging were generated and compared. In addition, metastatic LN counts between the MDCT and the histopathological examinations and correlation between LN-sum and histopathological nodal status were analysed.

RESULTS

The total counts of metastatic LNs on MDCT was significantly smaller than those detected in histopathological assessments (p<0.0001). LN-sum showed significant correlation with the pathological N stage and the number of metastatic LNs (rho=0.69, 0.73, p<0.0001). The areas under the receiver operating characteristic curve were 0.896, and 0.835, for N stage ≥N2 and N3, with cut-off values of 12.5 and 23.5 mm, respectively. LN-sum provided better diagnostic performance than conventional MDCT staging for discriminating N0-2 versus N3; sensitivity, accuracy, PPV and NPV of LN-sum were significantly higher (80.4 versus 52.2%, 81.1 versus 68.5%, 71.2 versus 57.1%, and 88 versus 74.1%).

CONCLUSION

LN-sum may be sufficiently useful in assessing the N3 stage of AGC and may help to plan appropriate therapy for AGC patients.

Curcuminoid WZ35 synergize with cisplatin by inducing ROS production and inhibiting TrxR1 activity in gastric cancer cells

Background

Cisplatin is one of the most widely used chemotherapeutic agents, but its efficacy is limited by its side effects. Hence, it is of great significance to develop novel agents to synergize with cisplatin and decrease side effects. In our previous study, we demonstrated that WZ35, a novel curcumin analogue, exhibited potent anti-cancer effects in vitro and in vivo. Here, we investigated whether WZ35 synergize to potentiate cisplatin activity in gastric cancer cells.

Methods

Cell apoptosis and cellular ROS levels were analyzed by flow cytometry. TrxR1 activity in gastric cells or tumor tissues was determined by the endpoint insulin reduction assay. Western blot was used to analyze the levels of indicated molecules. Nude mice xenograft model was used to test the effects of WZ35 and cisplatin combination on gastric cancer cell growth in vivo.

Results

We found that WZ35 significantly enhanced cisplatin-induced cell growth inhibition and apoptosis in gastric cancer cells. Further mechanism study showed that WZ35 synergized the anti-tumor effects of cisplatin by inhibiting TrxR1 activity. By inhibiting TrxR1 activity, WZ35 combined with cisplatin markedly induced the production of ROS, activated p38 and JNK signaling pathways, and eventually induced apoptosis of gastric cancer cells. In vivo, WZ35 combined with cisplatin significantly suppressed tumor growth in a gastric cancer xenograft model, and effectively reduced the activity of TrxR1 in tumor tissues. Remarkably, WZ35 attenuated the body weight loss evoked by cisplatin treatment.

Conclusion

This study elucidated the underlying mechanisms of synergistic effect of WZ35 and cisplatin, and suggest that such a combinational treatment might potentially become a more effective regimen in gastric cancer therapy.

Electronic supplementary material

The online version of this article (10.1186/s13046-019-1215-y) contains supplementary material, which is available to authorized users.

Relationship between microRNA-27a and efficacy of neoadjuvant chemotherapy in gastric cancer and its mechanism in gastric cancer cell growth and metastasis

Objective: The aim of the present study is to investigate the relationship between microRNA-27a (miR-27a) and the efficacy of neoadjuvant chemotherapy in gastric cancer (GC) and its mechanism in the growth and metastasis of GC cells.

Methods: The expression of miR-27a in serum of 74 GC patients received neoadjuvant chemotherapy was detected by quantitative reverse transcriptase polymerase chain reaction (qRT-PCR). Clinical value and prognosis of miR-27a expression in predicting the efficacy of neoadjuvant chemotherapy in GC were evaluated. Besides, GC cells with low miR-27a expression were transfected with miR-27a mimics, and cells with high miR-27a expression were transfected with miR-27a inhibitors and secreted frizzled-related protein 1 (SFRP1) siRNA. A series of experiments were applied for the determination of cell viability, invasion and migration of GC cells.

Results: After neoadjuvant chemotherapy, the expression of miR-27a in serum of GC patients decreased significantly. Additionally, the expression of miR-27a in GC cell line was significantly higher than that in normal gastric mucosa cell line. Meanwhile, after down-regulating the expression of miR-27a in GC cells, the mRNA and protein expression of SFRP1 increased, the proliferation rate of cells slowed down, and the ability of invasion and migration decreased. Furthermore, combined with low expression of miR-27a and SFRP1, the proliferation rate of GC cells increased and the ability of invasion and migration increased.

Conclusion: Collectively, our study highlights that the high expression of miR-27a indicates the poor efficacy and prognosis of neoadjuvant chemotherapy in GC patients. Down-regulation of miR-27a can inhibit the growth and metastasis of GC cells via up-regulation of SFRP1.

Anti-Cancer Natural Products and Their Bioactive Compounds Inducing ER Stress-Mediated Apoptosis: A Review

Cancer is the second biggest cause of death worldwide. Despite a number of studies being conducted, the effective mechanism for treating cancer has not yet been fully understood. The tumor-microenvironment such as hypoxia, low nutrients could disturb function of endoplasmic reticulum (ER) to maintain cellular homeostasis, ultimately leading to the accumulation of unfolded proteins in ER, so-called ER stress. The ER stress has a close relation with cancer. ER stress initiates unfolded protein response (UPR) to re-establish ER homeostasis as an adaptive pathway in cancer. However, persistent ER stress triggers the apoptotic pathway. Therefore, blocking the adaptive pathway of ER stress or facilitating the apoptotic pathway could be an anti-cancer strategy. Recently, natural products and their derivatives have been reported to have anti-cancer effects via ER stress. Here, we address mechanisms of ER stress-mediated apoptosis and highlight strategies for cancer therapy by utilizing ER stress. Furthermore, we summarize anti-cancer activity of the natural products via ER stress in six major types of cancers globally (lung, breast, colorectal, gastric, prostate and liver cancer). This review deepens the understanding of ER stress mechanisms in major cancers as well as the suppressive impact of natural products against cancers via ER stress.

High level of homeobox A9 and PBX homeobox 3 expression in gastric cancer correlates with poor prognosis

The homeobox protein homeobox (HOXA9) is a transcriptional factor that regulates patterning during embryogenesis and controls cell differentiation. HOXA9 dysfunction has been implicated in certain cancers. However, the role of HOXA9 in gastric cancer is poorly understood. The present study investigated HOXA9 and its cofactor PBX homeobox 3 (PBX3) expression in patients with gastric cancer. Paired tissue samples from 24 patients and paraffin embedded tissues of gastric cancer patients (104 males and 24 females) were included. HOXA9 and PBX3 expression levels were determined by reverse transcription quantitative polymerase chain reaction in fresh tissues, and by immunohistochemical staining in paraffin embedded tissues. The association between HOXA9/PBX3 expression and clinicopathological features was established. The results demonstrated that HOXA9 and PBX3 mRNA levels were significantly upregulated (P=0.032 for HOXA9 and P=0.031 for PBX3) in gastric cancer tissue. Immunohistochemical staining revealed that HOXA9 expression was associated with differentiation, lymph node metastasis and tumor-node-metastasis (TNM) stage, and PBX3 expression was associated with lymph node metastasis and TNM stage. Correlation analysis revealed a high coincidental expression of HOXA9 and PBX3 levels in gastric cancer (r=0.391; P<0.001). Survival analysis showed that high expression of HOXA9 or PBX3 was associated with poor survival of gastric cancer, and multivariate analysis using Cox's regression model showed that PBX3 expression was an independent prognostic factor in gastric cancer. There was elevated expression of HOXA9 and PBX3 in gastric cancer patients, and high-level expression of those proteins was associated with poor prognosis of gastric cancer. The present study underlines the significance of HOXA9/PBX3 in the development of gastric cancer.

Curcumin suppresses gastric tumor cell growth via ROS-mediated DNA polymerase γ depletion disrupting cellular bioenergetics

Background

Curcumin, as a pro-apoptotic agent, is extensively studied to inhibit tumor cell growth of various tumor types. Previous work has demonstrated that curcumin inhibits cancer cell growth by targeting multiple signaling transduction and cellular processes. However, the role of curcumin in regulating cellular bioenergetic processes remains largely unknown.

Methods

Western blotting and qRT-PCR were performed to analyze the protein and mRNA level of indicated molecules, respectively. RTCA, CCK-8 assay, nude mice xenograft assay, and in vivo bioluminescence imaging were used to visualize the effects of curcmin on gastric cancer cell growth in vitro and in vivo. Seahorse bioenergetics analyzer was used to investigate the alteration of oxygen consumption and aerobic glycolysis rate.

Results

Curcumin significantly inhibited gastric tumor cell growth, proliferation and colony formation. We further investigated the role of curcumin in regulating cellular redox homeostasis and demonstrated that curcumin initiated severe cellular apoptosis via disrupting mitochondrial homeostasis, thereby enhancing cellular oxidative stress in gastric cancer cells. Furthermore, curcumin dramatically decreased mtDNA content and DNA polymerase γ (POLG) which contributed to reduced mitochondrial oxygen consumption and aerobic glycolysis. We found that curcumin induced POLG depletion via ROS generation, and POLG knockdown also reduced oxidative phosphorylation (OXPHOS) activity and cellular glycolytic rate which was partially rescued by ROS scavenger NAC, indiating POLG plays an important role in the treatment of gastric cancer. Data in the nude mice model verified that curcumin treatment significantly attenuated tumor growth in vivo. Finally, POLG was up-regulated in human gastric cancer tissues and primary gastric cancer cell growth was notably suppressed due to POLG deficiency.

Conclusions

Together, our data suggest a novel mechanism by which curcumin inhibited gastric tumor growth through excessive ROS generation, resulting in depletion of POLG and mtDNA, and the subsequent disruption of cellular bioenergetics.

VCPA, a novel synthetic derivative of α-tocopheryl succinate, sensitizes human gastric cancer to doxorubicin-induced apoptosis via ROS-dependent mitochondrial dysfunction

Gastric carcinoma is a common malignant disease worldwide and has a dismal prognosis. Doxorubicin (DOX), one of the most widely used chemotherapeutic agents, has limited use because of its side effects and the development of tumor-cell resistance. Combinations of doxorubicin and non-cross-resistant agents have been required for adjuvant chemotherapy of gastric cancer. Here, we report that VCPA, a novel synthetic derivative of α-Tocopheryl Succinate, induced apoptosis via production of reactive oxygen species (ROS). When used in combination with doxorubicin, lower doses of VCPA sensitized human gastric cancer cells to DOX-induced apoptosis. The DOX/VCPA combination treatment caused an imbalance in the ratio of Bcl-2 to Bax and induced a lethal mitochondrial dysfunction. MAPKs were also activated in response to the DOX/VCPA treatment but played a protective role in DOX-induced cell death. In vivo studies further confirmed the sensitizing effect of VCPA. Combining DOX with VCPA markedly inhibited tumor growth in a tumor xenograft model of human gastric cancer. Taken together, our study revealed that VCPA, through increased ROS production, could synergize with DOX and circumvent DOX resistance in human gastric cancer cells.

Can low-dose CT perfusion imaging accurately assess response of advanced gastric cancer with neoadjuvant chemotherapy?

PURPOSE

To explore the value of low-dose CT perfusion imaging (LDCTPI) technology and its perfusion parameters in assessing response of neoadjuvant chemotherapy (NAC) in patients with advanced gastric cancer (AGC).

METHODS

Thirty patients with AGC were studied prospectively by LDCTPI to measure two parameters including blood flow (BF) and blood volume (BV) of tumor area before and after chemotherapy, respectively. All of the patients received two courses of NAC and surgical resection of gastric tumor within one week after chemotherapy, and then obtained the result of postoperative pathology response for chemotherapy. The comparisons of BF and BV values of AGC before and after chemotherapy were analyzed by paired-samples t-test, respectively; and the correlations between BF as well as BV decrease rates after NAC and the pathology response grade were analyzed by Spearman statistical test. Thirty patients were divided into effective and ineffective groups according to different pathology response grade. Comparisons of BF as well as BV decrease rates between effective and ineffective groups were analyzed by independent-samples t-test, respectively. Receiver operating characteristic (ROC) curves were used to determine the cutoff values of BF and BV decrease rates as evaluation indicators of AGC after NAC and calculate area under the curve (AUC).

RESULTS

There were significant differences in BF and BV values of AGC between before and after NAC (p < 0.001), respectively, and there were obvious correlations between BF as well as BV decrease rates and pathology response grade (r = 0.660, p < 0.001; r = 0.706, p < 0.001), respectively. There were also significant differences in BF and BV decrease rates of AGC between effective and ineffective groups (P = 0.001), respectively. If BF decrease rate of 12.1% (AUC was 0.816, P = 0.005) was used as the cutoff value for chemotherapy effectiveness of AGC, the sensitivity of 82% and specificity of 84% were achieved, and if BV decrease rate of 32.8% (AUC was 0.844, P = 0.002) was used as the cutoff value for chemotherapy effectiveness of AGC, the sensitivity of 82% and specificity of 89% were achieved.

CONCLUSIONS

BF and BV decrease rates have potential to be used as effective indicators to assess chemotherapy efficacy of AGC from the hemodynamics.

ROS generation mediates the anti-cancer effects of WZ35 via activating JNK and ER stress apoptotic pathways in gastric cancer

Gastric cancer is one of the leading causes of cancer mortality in the world, and finding novel agents and strategies for the treatment of advanced gastric cancer is of urgent need. Curcumin is a well-known natural product with anti-cancer ability, but is limited by its poor chemical stability. In this study, an analog of curcumin with high chemical stability, WZ35, was designed and evaluated for its anti-cancer effects and underlying mechanisms against human gastric cancer. WZ35 showed much stronger anti-proliferative effects than curcumin, accompanied by dose-dependent induction of cell cycle arrest and apoptosis in gastric cancer cells. Mechanistically, our data showed that WZ35 induced reactive oxygen species (ROS) production, resulting in the activation of both JNK-mitochondrial and ER stress apoptotic pathways and eventually cell apoptosis in SGC-7901 cells. Blockage of ROS production totally reversed WZ35-induced JNK and ER stress activation as well as cancer cell apoptosis. In vivo, WZ35 showed a significant reduction in SGC-7901 xenograft tumor size in a dose-dependent manner. Taken together, this work provides a novel anticancer candidate for the treatment of gastric cancer, and importantly, reveals that increased ROS generation might be an effective strategy in human gastric cancer treatment.

Auranofin induces apoptosis by ROS-mediated ER stress and mitochondrial dysfunction and displayed synergistic lethality with piperlongumine in gastric cancer

Gastric cancer (GC) is one of the leading causes of cancer mortality in the world. In addressing the need of treatments for relapsed disease, we report the identification of an existing U.S. Food and Drug Administration-approved small-molecule drug to repurpose for GC treatment. Auranofin (AF), clinically used to treat rheumatic arthritis, but it exhibited preclinical efficacy in GC cells. By increasing intracellular reactive oxygen species (ROS) levels, AF induces a lethal endoplasmic reticulum stress response and mitochondrial dysfunction in cultured GC cells. Blockage of ROS production reversed AF-induced ER stress and mitochondrial pathways activation as well as apoptosis. In addition, AF displays synergistic lethality with an ROS-generating agent piperlongumine, which is a natural product isolated from the long pepper Piper longum L. Taken together, this work provides a novel anticancer candidate for the treatment of gastric cancer. More importantly, it reveals that increased ROS generation might be an effective strategy in treating human gastric cancer.