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Golgi protein 73 (GP73) is a type II Golgi transmembrane protein which is overexpressed in several cancers, however, its role in gastric cancer is still unclear. The aim of this study is to investigate if high GP73 expression is associated with pathological tumor response to neoadjuvant chemotherapy and prognosis for patients with gastric cancer. A total of 348 patients with gastric cancer, who had undergone surgery between 1999 and 2011 were retrospectively reviewed, GP73 expression was examined in tumor tissues using tissue microarray and the correlations between its expression and pathological response to neoadjuvant chemotherapy as well as patients prognosis were analyzed. We found that GP73 expression was not associated with clinicopathologic features including tumor size, differentiation and TNM stage. High expression of GP73 was associated with less pathological tumor response to neoadjuvant chemotherapy and poor survival in gastric cancer, multivariate analysis showed GP73 expression was an independent predictive factor for pathological response to neoadjuvant chemotherapy and for prognosis in patients with gastric cancer. Our results suggest that GP73 expression correlates with the effect of neoadjuvant chemotherapy and is a promising biomarker to identify patients with poor prognosis.
Gastric cancer (GC) is now the fourth most common cancer and is the second most common cause of death from cancer in the world. It is estimated that two-thirds of gastric cancer cases occur in developing countries and 42% in China alone [
Preoperative chemotherapy is now widely used in patients with locally advanced gastric cancer, since it can improve complete surgical resection so as to improve survival [
GP73, also known as GOLM1 and GOLPH2, is a type II Golgi protein which is normally located within the cis-Golgi complex [
In this study, we evaluated GP73 expression by immunohistochemistry (IHC) on a tissue microarray containing 348 gastric cancer tumor tissues, and tried to investigate the expression of GP73 and its relationship with pathological response in patients with neoadjuvant chemotherapy as well as prognosis in patients with gastric cancer.
The protocol of this study was reviewed and approved by the institutional review board (IRB) of Zhejiang University Affiliated Sir Run Shaw Hospital (SRRSH) (Approval code: 2016-0628-3). Written informed consent was obtained from all the patients enrolled in this study.
A total of 348 patients with gastric cancer who underwent surgical treatment in the department of surgical oncology, Sir Run Shaw hospital between 1996 and 2011 were enrolled into the study. Patient demographics and clinicopathologic characteristics, including tumor size, location, depth of invasion, tumor differentiation, node status and TNM stage were documented. Patients clinically staged as T2 and above or having lymph node metastasis were recommended to have neoadjuvant chemotherapy, and the effect of chemotherapy was assessed based on the RECIST criteria. Surgical treatment was generally performed according to the rules of the Japanese Research Society for Gastric Cancer. After surgery, tumor specimens were sent to the Pathology and the pathologic stage was determined according to the rules of the sixth edition of UICC and the stage grouping of the UICC/AJCC. Pathological response was evaluated among the patients with neoadjuvant chemotherapy by using tumor regression grade (TRG), which was proposed by Mandard’s et al. [
GP73 expression was evaluated in 348 gastric cancer tissues by IHC in TMA. The construction of TMA was previously reported [
The IHC staining of cytoplasmic GP73 were evaluated by two pathologists independently, based on the intensity and the proportion of positively stained cancer cells. The proportion of positively stained cancer cells was scored as follows: 0 for no positive tumor cells, 1 for <10% positive tumor cells, 2 for 10–35% positive tumor cells, 3 for 35–70% positive tumor cells and 4 for >70% positive tumor cells. The intensity was scored as: 0 (no staining), 1 (weak staining), 2 (moderate staining) and 3 (strong staining). Scores for intensity and proportion of positive cells were multiplied as final histoscores of the samples. Scores ≤3 was regarded as tumors with low or no GP73 expression and scores ≥4 as high GP73 expression.
All demographic data, clinicopathologic variables and IHC results were coded and entered into a gastric cancer database. Double data entry and logic checks were used for error reduction. All statistical analyses in the study were performed by SPSS 22.0 (SPSS, Chicago, IL, United States). The Chi-square test and Fisher’s exact test were performed to assess the correlations between GP73 expression level and clinical characteristics. Kaplan–Meier method was used to calculate the survival probabilities and log rank test was used to compare survival curves. Independent factors influencing the survival were determined by multivariate analysis using Cox regression model. Factors predicting neoadjuvant pathological response were determined by means of logistic regression analysis. A
GP73 expression was determined by IHC in 348 gastric cancer tissues on the TMA. GP73 was mainly localized in the cytoplasm of the cancer cells (
Immunohistochemistry staining of GP73 according to its expression. The IHC staining of GP73 in TMA was evaluated based on staining intensity and proportion of positively stained tumor cells. 1. negative staining (score 0); 2, weak staining (score 1); 3, medium staining (score 2); 4, strong staining (score 3).
Correlation between GP73 expression and clinicopathologic factors of 348 gastric cancer patients.
Characteristics | GP73 |
|
|
---|---|---|---|
Low or no. of cases (%) | High no. of cases (%) | ||
Age (Mean ± SD, years) | 58.1 ± 11.2 | 60.3 ± 12.9 | 0.087 |
Gender | 0.368 | ||
Female | 58 (54.2) | 49 (45.8) | |
Male | 133 (56.8) | 101 (43.2) | |
Unknown | 5 (71.4) | 2 (28.6) | |
Tumor location | 0.335 | ||
Proximal | 33 (53.2) | 29 (46.8) | |
Middle | 48 (64.0) | 27 (36.0) | |
Low body | 99 (52.7) | 89 (47.3) | |
Whole | 6 (66.7) | 3 (33.3) | |
Unknown | 10 (71.4) | 4 (28.6) | |
Tumor size (Mean ± SD, cm) | 5.1 ± 2.7 | 5.8 ± 2.5 | 0.014 |
Differentiation | 0.898 | ||
Well or moderate | 56 (57.1) | 42 (42.9) | |
Poor or no | 94 (55.6) | 75 (44.4) | |
Unknown | 46 (55.4) | 35 (44.6) | |
T classification | 0.109 | ||
T1+T2 | 58 (63.7) | 33 (36.3) | |
T3+T4 | 132 (53.9) | 113 (46.1) | |
Unknown | 6 (50) | 6 (50) | |
LN metastasis | 0.457 | ||
No | 54 (60) | 36 (40) | |
Yes | 132 (55.2) | 107 (44.8) | |
Unknown | 10 (52.6) | 9 (47.4) | |
Peritoneal metastasis | 0.657 | ||
No | 192 (56.3) | 149 (43.7) | |
Yes | 2 (40.0) | 3 (60.0) | |
Unknown | 2 (100) | 0 (0) | |
TNM stage | 0.503 | ||
I + II | 84 (59.2) | 58 (40.8) | |
III + IV | 106 (54.9) | 87 (45.1) | |
Unknown | 6 (46.1) | 7 (53.9) | |
Neural invasion | 0.516 | ||
No | 171 (56.1) | 134 (43.9) | |
Yes | 24 (57.1) | 18 (42.9) | |
Unknown | 1 (100) | 0 (0) | |
Vascular invasion | 0.208 | ||
No | 185 (56.9) | 140 (43.1) | |
Yes | 9 (45.0) | 11 (55.0) | |
Unknown | 2 (66.7) | 1 (33.3) | |
Carcinomatous nodule | 0.273 | ||
No | 172 (57.5) | 127 (42.5) | |
Yes | 23 (47.9) | 25 (52.1) | |
Unknown | 1 (100) | 0 (0) | |
Type of surgery | 0.075 | ||
Radical | 157 (58.8) | 110 (41.2) | |
Palliative | 37 (48.7) | 39 (51.3) | |
Unknown | 2 (40.0) | 3 (60.0) |
Among the 348 patients, 179 patients (51.4%) died during the follow up period. Univariate analysis was conducted to investigate the relationship between the clinicopathologic characteristics and patients overall survival, we found that patient age, tumor location, tumor size, differentiation, neural invasion, carcinomatous nodule, tumor depth of invasion, lymph node metastasis, TNM stage, type of surgery as well as GP73 expression were associated with patients survival. Patients with high GP73 expression observed a shorter median overall survival than those with low or no GP73 expression (
Kaplan–Meier survival analysis for 348 gastric cancer patients with a low and no vs. a high GP73 expression tumors.
Univariate and multivariate analysis of gastric cancer with survival.
Univariate analysis | Multivariate analysis | |||
---|---|---|---|---|
Hr (95% CI) |
|
Hr (95% CI) |
|
|
Age (<60 vs. ≥60 years) | 1.105 (1.000–1.029) | 0.044 | 1.021 (1.001–1.042) | 0.041 |
Gender (female vs male) | 0.929 (0.587–1.470) | 0.753 | ||
Tumor location (P/W vs. M/L) | 0.545 (0.339–0.876) | 0.012 | 0.912 (0.696–1.194) | 0.502 |
Tumor size (<4 vs. ≥4 cm) | 1.144 (1.069–1.224) | 0.000 | 1.172 (0.643–2.136) | 0.604 |
Differentiation (well vs. Poor) | 1.591 (1.014–2.497) | 0.044 | 0.977 (0.784–1.218) | 0.837 |
Depth of invasion (T1,2 vs. T3,4) | 5.489 (2.745–10.977) | 0.000 | 2.060 (0.926–4.585) | 0.077 |
LN metastasis (no vs. Yes) | 2.600 (1.462–4.623) | 0.001 | 0.745 (0.312–1.779) | 0.507 |
Peritoneal metastasis (no vs. Yes) | 1.624 (0.401–6.575) | 0.497 | ||
TNM stage (I, II vs. III, IV) | 1.934 (1.519–2.460) | 0.000 | 1.843 (1.220–2.785) | 0.004 |
Neural invasion (no vs. Yes) | 2.794 (1.701–4.588) | 0.000 | 2.099 (1.204–3.659) | 0.009 |
Vascular invasion (no vs. Yes) | 1.202 (0.523–2.763) | 0.664 | ||
Carcinomatous nodule (no vs. Yes) | 2.612 (1.252–5.447) | 0.010 | 2.142 (0.996–4.607) | 0.051 |
Type of surgery (radical vs. palliative) | 4.920 (3.415–7.086) | 0.000 | 2.584 (1.557–4.288) | 0.000 |
GP73 expression (low or no vs. high) | 1.681 (1.095–2.579) | 0.018 | 1.636 (1.043–2.567) | 0.032 |
P/W: proximal/whole body; M/L: middle/low body.
Multivariate analysis using the Cox proportional hazard model was employed to identify the prognostic factors in gastric cancer patients, all variables that were significant in univariate analysis were entered into the model. Our results showed that high GP73 expression was one of the independent prognostic factors for survival in gastric cancer patients (
Forty-three out of 348 patients (12.4%) with locally advanced gastric cancer received neoadjuvant chemotherapy before surgery, among them, 74.4% of patients treated with oxaplatin-based regimens and the others (25.6%) with docetaxel-based regimens, and 55.8% patients completed more than three cycles of neoadjuvant chemotherapy before surgery. Nine patients (20.9%) showed high GP73 expression and 34 patients showed low or no GP73 expression. Pathologic tumor response after neoadjuvant chemotherapy was routinely assessed by the pathologist by using TRG. TRG1 was observed in 17 patients (39.5%), TRG2 in 16 patients (37.2%), TRG3 in 8 patients (18.6%) and TRG4 in 2 patients (4.7%), respectively. Ten patients (23.3%) showed tumor regression (TRG 3 or 4) as defined in the present study, and 2 patients showed complete regression.
The relationship between neoadjuvant pathological response and clinicopathologic parameters as well as treatment variables including age, gender, tumor staging, tumor location, differentiation, tumor size, peritoneal metastasis, neural invasion, vascular invasion and chemotherapy regimens were evaluated using univariate analysis, univariate predictors of tumor regression were found to be tumor size and GP73 expression. Patients with larger tumor size showed less tumor regression as compared with those with smaller tumor size (
Correlation between GP73 expression and tumor regression grade of 43 gastric cancer patients with neoadjuvant chemotherapy.
GP73 expression |
|
||
---|---|---|---|
Low or no. of cases (%) | High no. of cases (%) | ||
Tumor regression grade | 0.023 | ||
1 | 10 (29.4) | 7 (77.8) | |
2 | 14 (41.2) | 2 (22.2) | |
3 and 4 | 10 (29.4) | 0 (0) |
Multivariate logistic analysis to identify predictors of tumor regression in patients with neoadjuvant chemotherapy.
Variables | Odds ratio | 95% CI |
|
---|---|---|---|
GP73 expression (high vs. low or no) | 10.647 | 1.050–107.954 | 0.045 |
Tumor size (cm) (continuous) | 1.494 | 1.060–2.108 | 0.022 |
In the present study, we found that high GP73 expression was associated with poor outcome in patients with gastric cancer and was an independent prognostic factor for survival. To the best of our knowledge, this is the first study to evaluate the correlation between GP73 expression and pathological response to chemotherapy in gastric cancer. Patients with high GP73 expression were more likely to obtain less pathological tumor regression as compared to patients with low or no GP73 expression, these results indicate that GP73 correlates with the effect of neoadjuvant chemotherapy in advanced gastric cancer.
GP73 was originally cloned from a library derived from the liver tissue of a patient with adult giant-cell hepatitis [
The relationship between GP73 expression and gastric cancer progression is still controversial. A study from Chen et al. assessed GP73 protein expression by immunohistochemistry in both tumor and non-tumorous gastric mucosal tissue, they found GP73 was down-regulated in gastric cancer, and its expression in gastric cancer was associated with tumor differentiation [
The prognostic effect of GP73 expression was reported in some cancers. A study from Jiang et al showed that patients with high GP73 expression achieved poorer outcome than those with low or no GP73 expression in hepatocellular carcinoma (HCC) [
A recent randomized phase III trial demonstrated a survival benefit for gastric cancer patients with perioperative chemotherapy when compared with surgery alone [
The mechanism of the correlation between GP73 expression and chemotherapy response in cancer is unclear. Ye et al reported that GP73 may significantly change cell proliferation and apoptosis so as to influence the oxaplatin resistance in hepatic carcinoma cells [
Based on our data, there were some weaknesses in the study. Firstly, as we know now, tumor histological type was associated with the response rate to neoadjuvant chemotherapy in gastric cancer, however, data of histological type was not available in this study and the distribution of GP73 expression by histological type was unclear. Secondly, most of patients enrolled in the study were treated before 2010, thus, patients staging were determined by the sixth edition of the TNM system, it is unclear whether the influence of GP73 expression on prognosis will be changed if the latest edition of TNM staging is used in this study. Finally, our results were based on a small number of patients’ analysis with a short median follow-up time and need to be validated in large-scale studies.
In conclusion, our results suggest that GP73 correlates with the effect of neoadjuvant chemotherapy in gastric cancer and may serve as a promising biomarker to identify patients with poor prognosis, however, its potential role in the management of patients with gastric cancer needs to be further studied.
The raw data supporting the conclusions of this article will be made available by the authors, without undue reservation.
The studies involving human participants were reviewed and approved by Institution Ethics Committee of Sir Run Shaw hospital. The patients/participants provided their written informed consent to participate in this study.
JS and QW were responsible for the conception, design, and acquisition of data, JS, RT and LW analyzed and interpreted the data. JS wrote the final draft. All authors read and approved the final manuscript.
This study was supported by the Grant of the Zhejiang National Science Funding (No. LY18H160005) and the Zhejiang Medical Association Clinical Research Fund Project (No. 2019ZYC-A02).
The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.
GP73, Golgi protein 73; TMA, tissue microarray; GC, Gastric cancer; IHC, immunohistochemistry; TRG, tumor regression grade; HCC, hepatocellular carcinoma