Prognosis and predictive value of heat-shock proteins expression in oral cancer: A PRISMA-compliant meta-analysis.

BACKGROUND: Heat-shock proteins (HSP) is a key chaperone protein which maintains intracellular proteostasis and is expressed on the surface of solid and hematological malignancies. Several studies have reported paradoxical evidence of the association between HSP expression and prognosis of oral cancer. To address the discrepancy, we carried out the meta-analysis to assess the role of HSP such as: HSP70, HSP90, HSP27, HSP60, and HSP105 in susceptibility, progression, and prognosis of oral cancer.
MATERIALS AND METHODS: We retrieved the PubMed, Embase, Web of science, China National Knowledge Infrastructure (CNKI), and Wanfang databases to acquire the eligible studies which were associated with HSP70, HSP90, HSP27, HSP60, and HSP105 protein expression and oral cancer. We applied hazard ratio (HR) and its 95% confidence interval (95% CI) to assess the value of HSP protein expression in overall survival of oral cancer; odds ratio (OR) and its 95% CI were used to evaluate the association of risk and clinical features of oral cancer. Funnel plot, Begg test, and Egger line regression test were utilized to observe publication bias among studies. All statistical analysis was performed with Stata 14.0 software (Stata Corporation, College Station, TX).
RESULTS: A total of 26 studies were included in the present meta-analysis. On based of the results, HSP70 and HSP27 had no significant association with progression of oral cancer. However, the pooled HR and 95% CI revealed a significant well effects of HSP70 and HSP27 expression on survival of oral cancer. Moreover, the susceptibility of oral cancer was significantly associated with HSP70 and HSP60 overexpression.
CONCLUSION: HSP70 and HSP27 protein overexpression might be valuable biomarkers for the prognosis of oral cancer. And HSP70 and HSP60 might have potential predictive effects on the risk of oral cancer.

Introduction

Oral cancer is the most common cancer of head and neck malignancies worldwide, in which oral squamous cell carcinoma accounts for 90% of oral cancers. And the 5 years survival rate of oral cancer patients is approximately 63%.[ In the past few decades, the overall survival rate was not significantly increased, which mainly attributed to recurrence and distant metastasis of oral tumor.[ Oral cancer is not very commonly in western countries, but it is very prevalent in India which accounts for nearly 45% of all cancers, and the mainly cause is betel nut chewing.[ Other environmental factors are also important in the incidence of oral cancer such as: sun exposure, alcohol and tobacco, and human papilloma virus in which approximately 14% oral cancer cases presented the infection of human papilloma virus (HPV-16 and HPV-18).[ Several germline gene mutations were significantly associated with higher incidence of oral cancer. For instance, Li-Fraumeni syndrome patients with germline TP53 mutation often developed into early-onset oral cancer.[ In addition, dyskeratosis congenita patients had a higher tendency to get oral cancer due to defective telomerase maintenance.[ Lots of genetics or epigenetics alterations were found in cancerous cells which included gene mutations, deletions, translocations, gene copy number variation, microsatellite instability, loss of heterozygosity, DNA methylations, and acetylation of protein.[ These variations leaded to many disorders of cell function including deregulation of growth, genomic instability, increased oxidative stress, increased proteotoxic stress, evading immune surveillance, ineffective xenobiotic metabolism, evading cell death and senescence, limitless replicative potential, sustained angiogenesis, tissue invasion, and metastasis.[ The study of signal transduction pathway was a pivotal way to investigate interaction between molecules which derived cancers. Epidermal growth factor receptor (EGFR) could sustain normal cell growth which the expression was often changed in cancer cells, thus it was widely studied in the growth of tumor cells. These members of EGF family included EGFR, Her-2, Her-3, and Her-4 which were homodimers or heterodimers, and their ligands included the molecules of MAPK, PI3K/AKT, mTOR, JAK, and STAT signal pathways.[ Moreover, RAS gene including H-RAS, K-RAS and N-RAS, PI3K/NF-kB, Cyclin D1, Bcl-2, Bax, Survivin, p53/p21/p27, vascular endothelial growth factor (VEGF), Cadherins, Matrix metalloproteinases, and COX-2 were all involved in the occurrence and development of oral cancer.[ Although the possible biomarkers were growing, there was still few transfer of these molecules into clinical application. Therefore, we should develop more biomarkers for the early diagnosis and treatment of oral cancer. And we may have a good understanding of the development of oral cancer by these molecules.

Heat shock protein (HSP) is one of the most abundant intracellular substances, which are conserved proteins throughout evolution.[ This class of proteins maintain the essential functions of the cell under physiological conditions and protect cells from high temperature or different stresses including oxygen free radicals, infections, inflammation, hyperthermia, heavy metals, and ischemia.[ HSPs could assists in protein folding to form a normal spatial structure and carry these proteins toward organelles to make it function properly.[ Other studies also demonstrated that HSPs activated the immune system to suppress tumors progression.[ In recent years, the associations of HSPs including HSP70, HSP27, HSP90, HSP60, and HSP105 with risk, progression, and prognosis were widely studied in clinical samples of oral cancer. However, we could not acquire a consistent conclusion after literature retrieval because of contradictory results. Therefore, we performed the meta-analysis to investigate the correlation between HSP protein expression in tissues and oral cancer.

Materials and methods

Search strategy

According to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines, we carried out this meta-analysis.[ The searching of eligible articles was updated to May 29, 2020 from the PubMed, Embase, Web of science, NCBI, and Wanfang databases, which was performed by 2 researchers independently. To acquire the relevant studies, the following search terms were used: “oral cancer,” “oral carcinoma,” “oral squamous cell carcinoma,” “carcinoma of gingiva,” “tongue cancer,” “cancer of tongue,” “squamous cell carcinoma of the tongue,” “cancer of lip,” “heat shock protein,” “HSP70,” “HSP27,” “HSP60,” “HSP90,” “HSP105,” and “prognosis.” Additional eligible articles in the references list were obtained by manual searching.

Inclusion and exclusion criteria

All eligible studies had to meet the following inclusion criteria: case-control studies or cohort; articles assessing the association between HSP protein expression and oral cancer; articles providing enough information for calculating OR, HR, and 95% CI; studies which classified HSP expression as “high” and “low” or “positive” and “negative”. The exclusion criteria were as follows: meta-analysis, review, case-report, letter, review, comments, editorials, and conference abstracts; non-human research or cell studies; studies not focused on the independent role of HSP protein expression in oral cancer.

Data extraction and quality assessment

Two investigators independently read the titles and abstract to select eligible studies and extract acquired information. These information included first author information, the date of publication, country, ethnicity of subjects, subtype of oral tumors, positive or negative of COX-2 protein expression, clinical information of oral cancer such as: clinical stage, grade, prognosis of oral cancer, lymph node metastasis, and differentiation of oral tumor. Hazard ratio (HR) and 95% confidence interval (CI) were extracted from relevant studies. If the eligible studies did not provide HR and 95% CI, we extracted the value from Kaplan–Meier curve with Engauge Digitizer version 4.1.[ The quality of eligible studies were assessed by 2 researchers on based of the Newcastle-Ottawa Scale (NOS) criteria 100.[ The range of quality score was 0 to 9, and the quality score of ≥6 was considered as a high quality. In addition, approval of an ethics committee or institutional review board is not needed since this is a meta-analysis.

Statistical analysis

We carried out Cochran Q and I2 tests to find the heterogeneity among studies.[ When I2 > 50% or the corresponding P value <.05, HR, odds ratio (OR), and their 95% CI were calculated with a random effect model; otherwise, a fixed effect model was applied to estimate the pooled results.[ In addition, subgroup analysis based on race was further performed to find the source of heterogeneity. In order to observe the effect of each signal study on the pooled results, sensitivity analysis was conducted. Publication bias among eligible studies was also evaluated by Egger test and Begg funnel plot.[ All the statistical analysis was carried out by using Stata 14.0 software, while P value <.05 was considered as a statistical significance.

Results

Literature searching and characteristics of included studies

In the present study, a total of 26 studies involving HSP70, HSP27, HSP60, HSP90, HSP105 protein expression and oral cancer were included to assess clinical predictive and prognostic value of HSP expression (Tables 1 and 2). Most studies were focused on the association of HSP70 and HSP27 with oral cancer. Of 26 eligible studies, there were 13 studies were on HSP70 protein expression and oral cancer[ (315 patients), 9 on HSP27[ (111 patients), 4 on HSP90[ (90 patients), 3 on HSP60[ (60 patients), and 2 on HSP105[ (126 patients). Two published studies were conducted for the prognosis value of HSP70[ and 3 for HSP27[ protein expression in oral cancer. The eligible studies retrieval process was summarized in Fig. 1. The study contained 3 oral cancer subtypes: oral squamous cell carcinoma (OSCC), squamous cell carcinoma of the tongue (SCCT), and oral leukoplakia cancer (OLC). The detection method of HSP protein was IHC in oral cancer tissue or normal oral mucosa tissue.

Table 1

Eligible studies for association of HSP protein expression with prognosis of oral cancer.

												OS
	Author	Reference	Time	Country	Ethnicity	Cancer type	Num.	Follow-up, mo	Method	Survival analysis	Source of HR	HR	LL	UL	P
HSP70	Kaur	[24]	1998	India	Asians	OSCC	125	0–60	IHC	OS	Curve	2.13	1.57	4.62	<.05
	Tavassol	[43]	2011	Germany	Caucasians	OSCC	28	0–144	IHC	OS	Curve	0.44	0.07	0.95	<.05
HSP27	Mese	[35]	2002	Japan	Asians	OSCC	40	0–48	IHC	OS	Curve	0.247	0.12	0.686	<.01
	Wang	[40]	2009	USA	Caucasians	SCCT	42	0–100	IHC	OS	HR	0.375	0.19	0.741	.048
	Chen	[39]	2018	China	Asians	SACC	67	0–120	IHC	OS	Curve	0.64	0.24	0.982	.049
HSP90	Chang	[44]	2017	China	Asians	OSCC	36	0–60	IHC	OS	Curve	2.36	1.85	5.39	.013
HSP105	Arvanitidou	[45]	2019	Switzerland	Caucasians	OSCC	70	0–130	IHC	OS	Curve	2.79	1.18	7.44	.042

Table 2

Eligible studies for the HSP70, HSP27, HSP60, HSP90 protein expression and risk of oral cancer.

								Control		Case
	Author	Reference	Time	Country	Ethnicity	Method	Histology	HSP70–	HSP70+	HSP70–	HSP70+	Cut-off value	NOS
HSP70	Sugerman	[21]	1995	Australia	Caucasians	IHC	OSCC	7	8	14	15	NR	6
	Kaur	[22]	1995	India	Asians	IHC	OSCC	25	0	8	30	NR	6
	Ito	[23]	1998	Japan	Asians	IHC	SCCT	3	21	0	24	NR	6
	Kaur	[24]	1998	India	Asians	IHC	OSCC	91	5	33	92	NR	6
	Yin	[25]	2006	China	Asians	IHC	OSCC	0	10	2	40	5%	6
	Markopoulos	[26]	2009	Greece	Caucasians	IHC	OSCC	10	0	0	30	0%	6
	Nair	[27]	2013	India	Asians	IHC	OSCC	0	5	3	24	10%	6
								HSP27–	HSP27+	HSP27–	HSP27+
HSP27	Ito	[23]	1998	Japan	Asians	IHC	SCCT	0	24	6	18	NR	6
	Suzuki	[28]	2007	Japan	Asians	IHC	OSCC	0	5	6	31	5%	6
	Li	[29]	2013	China	Asians	IHC	OSCC	12	8	10	40	10%	6
								HSP60–	HSP60+	HSP60–	HSP60+
HSP60	Ito	[23]	1998	Japan	Asians	IHC	SCCT	4	20	0	24	NR	6
	Chen	[30]	2005	China	Asians	IHC	OLC	8	3	2	16	5%	6
	Li	[31]	2016	China	Asians	IHC	OSCC	7	3	0	18	NR	6
								HSP90–	HSP90 +	HSP90–	HSP90+
HSP90	Yin	[25]	2006	China	Asians	IHC	OSCC	7	3	13	29	5%	6
	Feng	[32]	2009	China	Asians	IHC	OSCC	17	9	11	37	10%	8
	Ito	[23]	1998	China	Asians	IHC	SCCT	1	24	17	7	NR	6

Figure 1

Literature searching progress.

Prognostic value of HSP expression for OS

According to the published data of 2 included studies,[ we found that HSP70 protein overexpression was significantly associated with the well prognosis of oral cancer (HR = 0.15, 95% CI = 0.15–0.99, P < .05) (Fig. 2A). Similarly, there was a significant association of HSP27 overexpression with well prognosis of oral cancer (HR = 0.38, 95% CI = 0.21–0.56, P < .05)[ (Fig. 2B). Therefore, the results suggested that HSP27 and HSP70 overexpression significantly increased the survival rate of oral cancer patients which was consistent with their function of maintaining cell homeostasis. However, one included studies found that HSP105 positive expression was an unfavorable factor for oral cancer patients survival (P = .042, n = 103),[ while similar result was also found for HSP90 (P = .013, n = 30).[ Only little heterogeneity was found for HSP70 and prognosis of oral cancer (I2 = 77%, P = .037), so the random effects model was applied to calculate the pooled HR (Table 3).

Figure 2

Meta-analysis for the association of HSP27 and HSP70 with overall survival of oral cancer. A: Forest plot for overall survival in HSP70; B: Forest plot for overall survival in HSP27; C: Funnel plot for overall survival in HSP70; D: Funnel plot for overall survial in HSP27.

Table 3

Meta-analysis for association of HSP protein expression with risk, progression, and prognosis of oral cancer.

					Heterogeneity		Begg test		Egger test
Genes	Characteristics	Studies	Pooled OR/HR (95% CI)	P	I2 (%)	P	Z	P	T	P
HSP70	Risk	7	10.85 (1.37,86.13)	<.05	0.849	.000	0.000	1.000	–0.090	.929
	Caucasian	2	27.67 (0.01–52937.48)	>.05	0.924	.000	–	–	–	–
	Asian	5	10.85 (1.37, 86.13)	<.05	0.724	.006	1.710	.086	–1.490	.233
	Tumor grade	2	0.10 (0.01, 1.89)	>.05	–	–	–	–	–	–
	Tumor stage	6	0.53 (0.08–3.47)	>.05	0.838	.000	–0.240	1.000	–0.140	.898
	Lymph node metastasis	4	0.13 (0.01, 1.20)	>.05	0.836	.002	1.040	.296	–2.350	.257
	Differentiation	4	1.47 (0.17, 12.92)	>.05	0.787	.003	0.340	.734	3.870	.061
	T2	2	1.11 (0.50, 2.47)	>.05	0.000	.964	–	–	–	–
	Overall survival	2	0.57 (0.15, 0.99)	<.05	0.770	.037	0.000	1.000	–0.500	.704
HSP27	Risk	3	0.66 (0.03, 16.12)	>.05	0.823	.004	0.000	1.000	–2.930	.209
	Tumor grade	5	0.62 (0.32, 1.23)	>.05	0.557	.060	0.730	.462	0.860	.451
	Caucasians	2	0.55 (0.21, 1.43)	>.05	0.000	.988	–	–	–	–
	Asians	3	0.71 (0.27, 1.85)	>.05	0.775	.012	1.040	.296	10.670	.059
	Tumor stage	6	1.07 (0.35, 3.30)	>.05	0.682	.008	0.000	1.000	–0.710	.519
	Lymph node metastasis	6	0.57 (0.29, 1.11)	>.05	0.143	.323	0.380	.707	–0.240	.820
	Differentiation	4	1.13 (0.07, 19.33)	>.05	0.908	.000	–0.340	1.000	0.200	.859
	Overall survival	3	0.38 (0.21, 0.56)	<.05	0.268	.255	0.000	1.000	–0.940	.519
HSP90	Risk	3	0.94 (0.04, 24.57)	>.05	0.928	.000	1.040	.296	–1.890	.310
HSP60	Risk	3	23.91 (5.39, 10.6.16)	<.05	0.000	.647	0.000	1.000	0.280	.828

Correlation of HSP with clinicopathological features of oral cancer patients

Firstly, we observed the effects of HSP70, HSP27, HSP90, and HSP60 protein expression on the oral cancer risk, in which HSP70 (OR = 10.85, 95% CI = 1.37–86.13, P < .05) and HSP60 (OR = 23.91, 95% CI = 5.39–10.616, P < .05) were significantly correlated with susceptibility of oral cancer. And no significant correlations were found between HSP27, HSP90, and risk of oral cancer (Fig. 3). To further discuss the role of HSP in progression of oral cancer, we assessed the association of HSP with clinical features of oral cancer. The pooled ORs indicated that no positive results were found. In a single study, HSP105 overexpression was significantly associated advanced stage of oral cancer (P = .01).[ However, there were no correlation between HSP105 overexpression and grade of oral cancer.[ Although many studies found that HSP had a significantly association with progression of oral cancer, no positive results were found in the pooled overall results (Table 3).

Figure 3

Meta-analysis for the association of HSP27 and HSP70 with clinical features of oral cancer. A: Stage for oral cancer in HSP70; B: Differentiation for oral cancer in HSP70; C: Differentiation for oral cancer in HSP27; D: lymph node metastasis for oral cancer in HSP27.

Publication bias and sensitivity analysis

The results of Begg and Egger test indicated no significant publication bias was detected. Further, sensitivity analysis also confirmed the stability of the pooled HR and OR, and no individual study affected the overall result (Fig. 2C, D).

Discussion

Studies have found HSPs on the surface of malignant cells could function as antigens or carriers of antigens such as peptides and it could signal to effector molecules to activate the immune system.[ In addition, HSP family proteins also played important roles in regulating cellular responses and functions during carcinogenesis. Most studies were focused on the expression of HSP27 and HSP70 protein in oral cancer. HSP27 could regulate cancer development, diagnosis, and treatment, in which phosphorylation at Ser-15, Ser-78, and Ser-82 of HSP27 protein could enhance its activity which were induced by some stresses.[ p38 mitogen-activated protein kinase of MAPK signal pathway activated mitogen-activated protein kinase-activated protein kinases (MAPKAPK) 2 and 3 and further catalyzed phosphorylation of HSP27. Activated HSP27 could interact with β-catenin, histone deacetylases 6 (HDAC6), signal transducer and activator of transcription 2 (STAT2), and procaspase-3 and regulate the development and metastasis of cancer, cell apoptosis and drug resistance.[ Published studies suggested that HSP27 enchanced cells invasion of bladder tumor cells and was significantly associated with peritoneal metastasis of epithelial ovarian cancer.[ Furthermore, inhibition of HSP27 expression increased colon cancer sensitivity to 5-fluorouracil (5-FU) in a mouse model.[ Therefore, HSP27 might be a predictor, prognostic factor or potential therapeutic targets of cancers. HSP70 was a very conserved protein which had 3 domain structure: ATPase domain, substrate-binding domain, and the C-terminal domain.[ HSP70 could promote normal folding of proteins and enhance cell survival under stresses. It has been reported that HSP70 resisted TNF-induced cytotoxicity in cancer cells and even promoted tumor growth by immunological escape mechanism, thus HSP70 could promote tumorigenesis.[ Five proteins interacted with HSP70 and functioned together including: HSP72, HSPA6, HSPA9, GRP78, and HSC70.[ These 5 proteins were also significant associated with progression and prognosis of oral cancer. Although HSP90, HSP60, and HSP105 were well studied in other cancers, few studies were conducted in oral cancer.

In the present study, we included 3 studies to calculate the pooled HR to assess the association between HSP27 protein expression and overall survival of oral cancer,[ of which one study provided directly HR and other 2 studies only drawed survival curve. The pooled HR revealed that HSP 27 protein overexpression significantly increased the survival rate of oral cancer patients, which was consistent with the results of 3 published studies. No obvious heterogeneity among was found, so the results were robust. However, there were no significant association of HSP27 expression with risk and clinical characteristics of oral cancer. In 3 included studies,[ only one study indicated HSP27 overexpression significantly increased the risk of oral cancer.[ Interestingly, 4 studies were carried out to discuss the role of HSP27 in differentiation of oral cancer,[ one study[ got high risk result in OSCC and one study[ obtained opposite result in tongue cancer while 2 other studies did not find significant results in OSCC. HSP27 might have different roles in different subtype of oral cancers, and tumor stage might affect the HSP27 expression. So, the included samples should have in detailed information in future studies. For the grade and lymph node metastasis of oral cancer, no positive results were detected in the eligible studies and the pooled OR indicated same results. Finally, Li's study suggested that HSP27 overexpression had a protective role in the higher grade,[ but the pooled results did not got meaningful results.

The pooled results of included studies revealed that HSP70 overexpression was a protective factor for overall survival of oral cancer,[ of which study of Kaur et al indicated poor survival patients had a higher HSP70 protein expression. Thus, if we want to get a more accurate result, more samples need to be included and more relevant studies should be carried out. In the analysis for the susceptibility of oral cancer, HSP70 overexpression significantly increased the risk of oral cancer in Asians, which was consistent with the function of promoting the survival of tumor cells. However, the pooled OR indicated that there were no significant associations of clinical features of oral cancer with HSP70 expression. In fact, many conflicting results were acquired in the included studies for progression of oral cancer. For example, study of Zheng et al[ demonstrated patients with HSP70 overexpression had a more advanced stage of oral cancer, but Taghavi’ study found HSP70 overexpression was a protective factor for advanced stage.[ At the same time, opposite results were also detected for the differentiation or oral cancer,[ in which the 2 studies were all performed in OSCC patients. So we might confirm that HSP70 had a closely association with risk or prognosis of oral cancer, but the published studies could not provide definite results because of fewer studies and opposite results. It was worth noting that HSP70 protein expression levels might be different along with the development of oral cancer, which might explain the inconsistency of results.

Few studies were conducted for the association between HSP90 (4 studies),[ HSP60 (3 studies),[ and HSP105 (2 studies)[ protein expression and oral cancer. As mentioned above, many studies were carried to explore the function of HSP90 in cancer cells. HSP90 protein possesses alternative ATP-binding sites which are the binding site for nucleotides and for small molecules drugs such as nucleotides, novobiocin, and cisplatin.[ Due to intrinsic ATPase activity in HSP90 protein, it assists in protein folding, client protein, maturation, and protein trafficking and further is involved in PI3K/AKT pathway, JAK/STAT pathway, RAS/ERK pathway, and NF-kB pathway.[ So, HSP90 is associated with tumor growth, adhesion, metastasis, invasion, and angiogenesis.[ The results of meta-analysis did not found any significant association of HSP90 overexpression with risk of oral cancer patients. Ito’ study found HSP90 was a protective factor for risk of oral cancer.[ Only one study was conducted for the role of HSP90 overexpression for clinical stage of oral cancer in Asians, so we did not conduct pooled analysis for HSP90 expression and progression of oral caner. HSP60, locating in the mitochondria, cytosol, cell surface and we could detected it in peripheral blood.[ HSP60 could protect cancer cells from chemotherapeutic agents and promote cell survival which revealed HSP60 overexpression was a risk factor for oral cancer.[ Our pooled results were similar to previous findings, of which people with HSP60 protein overexpression was 23.91 times more likely to suffer from oral cancer. This was an encouraging result and no significant heterogeneity among studies were detected, so this result was stable and credible. In the literature retrieval, 2 studies which talked about HSP105 and oral cancer including OSCC and squamous cell carcinoma of the tongue were included.[ Arvanitidou et al[ found the patients with increased HSP105 expression presented a poor prognosis for malignancy (P = .042). And study conducted by Mohtasham et al[ demonstrated that HSP105 overexpression promoted the progression of oral tumor, in which patients with advanced stage had a higher HSP105 protein expression in epithelial cells. There was no obvious association between HSP105 protein expression and grade of oral tumor. In the latest study, HSP105 peptide vaccine induced immunological effects colorectal cancer and esophageal cancer patients and obciously improved their prognosis.[ The vaccine against the HSP protein might be used to treat oral cancer in the future. But before that, we still had to carry out numerous studies to investigate the role of HSP in progression and prognosis of oral cancer.

Several factors still limited statistical power of data. First, few studies were conducted for HSP60, HSP90, and HSP106. Although some studies were performed for HSP70 and HSP27, the number of included studies in subgroup analysis still was too small. Second, we found the HSP protein expression in eligible studies had a big difference, in which stage of patients or tumor subtype might affect the HSP expression. So, when we carried out the correlation analysis, clinical information and stratification analysis based on patients’ clinical stage would be very important. Third, the overall results revealed each HSP had special function for tumor cells, thus we could not put all the data together to calculate an overall OR and analyze the function of HSP, which leaded to complexity in understanding the pooled results. But, on the other hand, it might explain the importance of HSP family protein in cancer cells.

In general, HSP70 and HSP27 might be potential biomarkers for assessing the occurrence and prognosis of oral cancer. HSP60 overexpression was significantly associated with increased risk of oral cancer. However, given the small sample size, studies with more samples, detailed clinical information, especially clinicopathological data, should be carried out to observe the effects HSP family protein in risk, progression, and prognosis of oral cancer.

Author contributions

Data curation: Yongwu Wang, Min Gan.

Funding acquisition: Qingyun Duan.

Methodology: Wei Lu.

Software: Wei Lu.

Supervision: Qingyun Duan, Yongwu Wang.

Validation: Wei Lu, Yongwu Wang, Min Gan.

Visualization: Yongwu Wang.

Writing – original draft: Wei Lu.

Writing – review & editing: Wei Lu.