Bone invasion by oral squamous cell carcinoma: Molecular alterations leading to osteoclastogenesis – a review of literature

Osteoblasts are induced into cancer-associated osteoblasts to promote tumor progression in head and neck squamous cell carcinoma

Bone invasion by head and neck squamous cell carcinoma (HNSCC) significantly impacts tumor staging, treatment choice, prognosis, and quality of life. While HNSCC is known to cause osteolytic bone invasion, we found that specific HNSCC subtypes can induce osteogenic bone destruction at the tumor-bone interface. This destruction mode significantly correlated with reduced patient survival rates and increased neck lymph node metastasis. Further in vivo and in vitro experiments indicated that HNSCC cells triggered abnormal phenotypic changes in osteoblasts to remodel the tumor-bone microenvironment, facilitating tumor lymphatic metastasis. Through transcriptome analysis, we identified three genes-osteopontin (SPP1), chemokine (C-X-C motif) ligand 1 (CXCL1), and matrix metalloprotein (MMP)9 (MMP9) linked to a poorer prognosis. We discovered osteoblasts with abnormal phenotypes at the tumor-bone interface exhibiting high SPP1, MMP9, and CXCL1 expressions. Based on these characteristics, we identified this osteoblast subpopulation as "cancer-associated osteoblasts (CAOs)." HNSCC cells activated the TNF-α/NF-κB signaling pathway in osteoblasts, transforming them into "CAOs." These CAOs significantly contributed to the progression of tumor-induced bone invasion, facilitating cancer growth and metastasis. We first provided clinical data and in vivo and in vitro evidence that HNSCC cells can promote tumor progression by manipulating osteoblasts into "CAOs" in the bone invasion.

Underlying bone change in oral squamous cell carcinoma observed from magnetic resonance imaging and computed tomography: Potential implications for tumor aggressiveness and prognosis

Background

/purposeIn cases where oral squamous cell carcinoma (OSCC) invades the jawbone, clinicians frequently observe abnormal attenuation on computed tomography (CT) and pathologic signal intensity (SI) on magnetic resonance (MR) imaging of the affected underlying bone marrow. This study introduced a concept of "underlying bone change" to examine its association with clinicopathological features and prognosis of OSCC, as well as its correlation with medullary invasion.

Materials and methods

We enrolled 93 consecutive patients diagnosed with OSCC, who underwent mandibulectomy between 2010 and 2016. CT and MR images, along with electronic medical records, were reviewed to evaluate correlations between underlying bone changes, clinicopathological features, five-year overall survival, and medullary invasion.

Results

Of the 93 patients, 69 (74.2%) exhibited underlying bone sclerosis on CT, and 74 (79.6%) displayed pathological SI on MR images. These underlying bone changes correlated with the T stage and recurrence, but not with overall survival.Medullary invasion, observed in 61 (65.6%) patients, was strongly associated with T and TNM stages and was linked to poorer overall survival.The underlying bone changes on CT and MR images were positively associated with medullary invasion; however, no significant differences were found in the occurrence of underlying bone changes between the subtypes based on the extent of medullary invasion.

Conclusion

Underlying bone changes on CT and MR images can provide valuable insights into the aggressiveness of bone invasion by OSCC. Accurate interpretation of these imaging findings might be crucial for correctly delineating surgical margins and preventing the overestimation of tumor extent.

Assessment of the bony resection margin distance in bone-invasive oral cancer using laser-induced breakdown spectroscopy

OBJECTIVES

Inadequate resection margins of less than 5 mm impair local tumor control. This weak point in oncological safety is exacerbated in bone-infiltrating tumors because rapid bone analysis procedures do not exist. This study aims to assess the bony resection margin status of bone-invasive oral cancer using laser-induced breakdown spectroscopy (LIBS).

MATERIALS AND METHODS

LIBS experiments were performed on natively lasered, tumor-infiltrated mandibular cross-sections from 10 patients. In total, 5,336 spectra were recorded at defined distances from the tumor border. Resection margins < 1 mm were defined as very close, from 1-5 mm as close, and > 5 mm as clear. The spectra were histologically validated. Based on the LIBS spectra, the discriminatory power of potassium (K) and soluble calcium (Ca) between bone-infiltrating tumor tissue and very close, close, and clear resection margins was determined.

RESULTS

LIBS-derived electrolyte emission values of K and soluble Ca as well as histological parameters for bone neogenesis/fibrosis and lymphocyte/macrophage infiltrates differ significantly between bone-infiltrating tumor tissue spectra and healthy bone spectra from very close, close, and clear resection margins (p < 0.0001). Using LIBS, the transition from very close resection margins to bone-infiltrating tumor tissue can be determined with a sensitivity of 95.0%, and the transition from clear to close resection margins can be determined with a sensitivity of 85.3%.

CONCLUSIONS

LIBS can reliably determine the boundary of bone-infiltrating tumors and might provide an orientation for determining a clear resection margin.

CLINICAL RELEVANCE

LIBS could facilitate intraoperative decision-making and avoid inadequate resection margins in bone-invasive oral cancer.

Postoperative Radiotherapy in Advanced Stage Squamous Cell Carcinoma Requiring Maxillectomy

OBJECTIVE

To evaluate whether postoperative radiotherapy (PORT) improves survival among patients who received maxillectomy for pT4aN0 maxillary gingival or hard palate squamous cell carcinoma (SCC) with respect to tumor size.

STUDY DESIGN

Retrospective analysis.

SETTING

National Cancer Database from 2004 to 2019.

METHODS

Included adult patients who received maxillectomy (partial, subtotal, or total) and neck dissection for treatment-naive margin negative pT4aN0 SCC of the maxillary gingiva or hard palate. Adjusted for age, gender, race, insurance status, income, education, urban/rural, facility type, region, comorbidity index, tumor grade, and tumor extension. Inverse probability weights were incorporated into a multivariable Cox proportional hazards model. A priori post hoc subgroup analysis was performed according to tumor size.

RESULTS

We included 416 patients who underwent maxillectomy for pT4aN0 SCC of the maxillary gingiva or hard palate (mean [standard deviation] age, 71.5 [11.3] years; male, 190 [45.7%]; tumor size 2 cm, 362 [87%]). Overall, 49.3% of patients received PORT (205 patients). PORT was associated with a 50% improvement in survival compared to surgery alone (adjusted hazard ratio [aHR], 0.50; 95% confidence interval [95% CI], 0.32-0.81). On subgroup analysis, PORT was associated with improved survival for tumors 2 cm (aHR, 0.47; 95% CI, 0.29-0.77), but not for tumors < 2 cm (aHR, 1.15; 95% CI, 0.33-4.08).

CONCLUSION

The vast majority of patients with pT4aN0 bone-invading SCC of the maxillary gingiva and hard palate benefit from PORT. Patients with tumors < 2 cm did not demonstrate a survival benefit from adjuvant treatment, suggesting that bony invasion alone may not be sufficient criteria for treatment escalation.

Comparative clinicopathological study of the main anatomic locations of oral squamous cell carcinoma

OBJECTIVE

To analyze the clinicopathological and evolutionary profile of the main locations of oral squamous cell carcinoma (OSCC).

MATERIALS AND METHODS

This is a retrospective study on 133 patients treated for OSCC. The group was composed of 48 women and 85 men, with a mean age 63.9 ± 12.73 years. Most cases involved the lingual border of tongue (63), followed by the gingiva (36) and the floor of mouth (34). A comparative analysis was performed using multinomial regression.

RESULTS

There were significant differences regarding age, sex, tobacco and alcohol consumption, liver pathology, oral potentially malignant disorders, and bone and perineural invasion. In multivariate regression, tobacco consumption, and bone invasion remained significant. There were no significant differences in relation to prognosis.

CONCLUSION

The location of OSCC is an important factor in the clinicopathological assessment of this neoplasm. The main locations of OSCC show differential etiopathogenic and clinicopathological aspects. Tobacco consumption has a great relevance in the floor of mouth; nonetheless, it is less important in the tongue border and the gum, which suggests other pathogenic factors. It is necessary to consider the anatomical location of OSCC in preventive protocols, with the aim of reducing its high mortality.

Assessment of Bone Invasion and Its Correlation With Brandwein-Gensler Criteria in Oral Squamous Cell Carcinoma

Background The most prevalent form of head-neck cancer is squamous cell carcinoma (SCC). Apart from all sites like the tongue, labial mucosa, and buccal mucosa, the prevalence of oral squamous cell carcinoma (OSCC) is more common in gingivobuccal sulcus due to the habit of keeping tobacco quid. With regards to anatomical relationships in the mouth and proximity to bone, OSCC invades the maxilla and mandible. However, bone invasion significantly influences the pathological staging of OSCC. Histological parameters such as Brandwein-Gensler worst pattern of invasion (WPOI), lymphocytic host response (LHR), and perineural invasion (PNI) hold significance for determining the need for adjuvant therapy. This study aims to correlate Brandwein-Gensler Criteria (BGC) with bone invasion and also to include the bone invasion criteria as a prognostic parameter in OSCC. This study aimed to assess bone invasion and correlate it with Brandwein-Gensler criteria in OSCC. Methods The research was conducted retrospectively, analyzing 65 cases of OSCC that underwent surgical intervention. Data was gathered from the Oral Pathology department's archives at Sharad Pawar Dental College (SPDC), Wardha. Pathologists assessed bone invasion without the knowledge of other factors to minimize bias. Subsequently, the cases were classified into well-differentiated (WDSCC), moderately differentiated (MDSCC), and poorly differentiated squamous cell carcinomas (PDSCC) based on histological grading, followed by the evaluation of WPOI, LHR, and PNI using the Brandwein-Gensler risk scoring system. Results This study found a notable association between bone invasion and BGC, with a calculated significance level of p = 0.047. LHR shows patterns as 1, 2, and 3. There were five (7.6%) cases with pattern III, 45 (69.23%) cases with pattern II, and 15 (23.08%) cases with pattern I. Similarly, PNI is scored as 0, 1, and 3. There were seven (10.77%) cases with score 3, 17 (26.15%) with score 1, and 41 (63.03%) with score 0. In the case of the WOPI, which is classified as patterns I to V, there were seven (10.77%) cases with pattern V, 27 (41.54%) cases with pattern IV, 23 (35.38%) cases with pattern III, and eight (12.231%) cases with pattern II, whereas no cases were noted with pattern I. Conclusion Although bone invasion and BGC are independent parameters, the BGC score should be considered in treatment planning. Patients with bone invasion and those with a higher BGC score should be strongly considered for adjuvant treatment.

The role of potassium in depth profiling of the tumor border in bone-invasive oral cancer using laser-induced breakdown spectroscopy (LIBS): a pilot study

PURPOSE

Microscopic tumor spread beyond the macroscopically visible tumor mass in bone represents a major risk in surgical oncology, where the spatial complexity of bony resection margins cannot be countered with rapid bone analysis techniques. Laser-induced breakdown spectroscopy (LIBS) has recently been introduced as a promising option for rapid bone analysis. The present study aimed to use LIBS-based depth profiling based on electrolyte disturbance tracking to evaluate the detection of microscopic tumor spread in bone.

METHODS

After en bloc resection, the tumor-infiltrated mandible section of a patient's segmental mandibulectomy specimen was natively investigated using LIBS. Spectral and electrolytic depth profiles were analyzed across 30 laser shots per laser spot position in healthy bone and at the tumor border. For the histological validation of the lasered positions, the mandibular section was marked with a thin separating disc.

RESULTS

Solid calcium (Ca) from hydroxyapatite and soluble Ca from dissolved Ca can be reliably differentiated using LIBS and reflect the natural heterogeneity of healthy bone. Increased potassium (K) emission values in otherwise typically healthy bone spectra are the first spectral signs of tumorous bone invasion. LIBS-based depth profiles at the tumor border region can be used to track tumor-associated changes within the bone with shot accuracy based on the distribution of K.

CONCLUSION

Depth profiling using LIBS might enable the detection of microscopic tumor spread in bone. In the future, direct electrolyte tracking using LIBS should be applied to other intraoperative challenges in surgical oncology to advance rapid bone analysis by spectroscopic-optical techniques.

Jaw Bone Invasion of Oral Squamous Cell Carcinoma Is Associated with Osteoclast Count and Expression of Its Regulating Proteins in Patients and Organoids

AIMS

Oral squamous cell carcinoma (OSCC) frequently invades the jaw. The exact mechanism of bone invasion remains unclear. This study investigates (premature) osteoclasts and the expression of its differentiation regulating proteins RANKL, OPG and RANK in patients with OSCC.

METHODS

Resection specimens from OSCC patients were divided into NI group (No Invasion), E group (Erosion) or I group (bone Invasion). Tissue sections were stained with Cathepsin K (osteoclast-counting), RANKL, OPG and RANK. The staining intensity was scored on different regions of the tumor: front, center, back and normal mucosa. Immunohistochemistry and qPCR for RANKL/OPG/RANK were performed on five head and neck squamous cell carcinoma (HNSCC) organoids.

RESULTS

The mean number of osteoclasts (I group) and premature osteoclasts (E group) was significantly higher compared to the NI group (p = 0.003, p = 0.036). RANKL expression was significantly higher in the tumor front and tumor center compared to normal mucosa (all groups). In the I group, RANKL and RANK expression was significantly higher in the tumor front compared to the tumor back and there was a trend of higher RANKL expression in the tumor front compared to the E group and NI group. qPCR showed a 20-43 times higher RANKL mRNA expression in three out of five tumor organoids compared to a normal squamous cell organoid line. There was no correlation between protein and mRNA expression in the HNSCC organoids.

CONCLUSIONS

These findings suggest that OSCCs induce bone invasion by stimulating osteoclast activation by regulating the production of RANKL and RANK proteins.

IL-1 Generated by Oral Squamous Cell Carcinoma Stimulates Tumor-Induced and RANKL-Induced Osteoclastogenesis: A Possible Mechanism of Bone Resorption Induced by the Infiltration of Oral Squamous Cell Carcinoma

We previously observed a novel osteoclastogenesis system that is induced by oral squamous cell carcinoma (OSCC) cells, which target osteoclast precursor cells (OPC) without upregulation of the master transcriptional factor of osteoclastogenesis, NFATc1. Here, we analyzed inflammatory cytokines that were preferentially expressed in one of the osteoclastogenic OSCC cell lines, namely NEM, compared with the subclone that had lost its osteoclastogenic properties. Based on a gene expression microarray and a protein array analyses, IL-1, IL-6, IL-8, and CXCL1 were chosen as candidates responsible for tumor-induced osteoclastogenesis. From the results of the in vitro osteoclastogenesis assay using OPCs cultured with OSCC cells or their culture supernatants, IL-1 was selected as a stimulator of both OSCC-induced and RANKL-induced osteoclastogenesis. The IL-1 receptor antagonist significantly attenuated osteoclastogenesis induced by NEM cells. The stimulatory effects of IL-1 for OSCC-induced and RANKL-induced osteoclastogenesis were effectively attenuated with cannabidiol and denosumab, respectively. These results suggest that IL-1 secreted from OSCC cells stimulates not only tumor-induced osteoclastogenesis targeting OPCs but also physiological RANKL-induced osteoclastogenesis, and this may be the biological mechanism of bone resorption induced by the infiltration of OSCC. These results also suggest that IL-1 inhibitors are candidates for therapeutic agents against bone resorption induced by OSCC.

The Impact of Histopathological Features on the Prognosis of Oral Squamous Cell Carcinoma: A Comprehensive Review and Meta-Analysis

OBJECTIVE

Over many decades, studies on histopathological features have not only presented high-level evidence of contribution for treatment directions and prognosis of oral squamous cell carcinoma (OSCC) but also provided inconsistencies, making clinical application difficult. The 8th TNM staging system of OSCC has acknowledged the importance of some histopathological features, by incorporating depth of invasion (DOI) to T category and extranodal extension (ENE) to N category. The aim of this systematic review with meta-analysis is to determine the most clinically relevant histopathological features for risk assessment and treatment planning of OSCC and to elucidate gaps in the literature.

METHODS

A systematic review was conducted using PRISMA guidelines, and the eligibility criteria were based on population, exposure, comparison, outcome, and study type (PECOS). PubMed, Cochrane, Scopus, and Web of Science were searched for articles exploring the impact of histopathological features on OSCC outcomes with Cox multivariate analysis. Pooled data were subjected to an inverse variance method with random effects or fixed effect model, and the risk of bias was evaluated using quality in prognosis studies (QUIPS). Quality of evidence was assessed with the Grading of Recommendations Assessment, Development, and Evaluation (GRADE) criteria.

RESULTS

The study included 172 articles published from 1999 to 2021. Meta-analyses confirmed the prognostic potential of DOI, ENE, perineural invasion, lymphovascular invasion, and involvement of the surgical margins and brought promising results for the association of bone invasion, tumor thickness, and pattern of invasion with increased risk for poor survival. Although with a small number of studies, the results also revealed a clinical significance of tumor budding and tumor-stroma ratio on predicted survival of patients with OSCC. Most of the studies were considered with low or moderate risk of bias, and the certainty in evidence varied from very low to high.

CONCLUSION

Our results confirm the potential prognostic usefulness of many histopathological features and highlight the promising results of others; however, further studies are advised to apply consistent designs, filling in the literature gaps to the pertinence of histopathological markers for OSCC prognosis.

SYSTEMATIC REVIEW REGISTRATION

International Prospective Register of Systematic Reviews (PROSPERO), identifier CRD42020219630.

3D Bioprinting for In Vitro Models of Oral Cancer: Toward Development and Validation

The tumor microenvironment (TME) of oral carcinomas has highly complex contents and a dynamic nature which is difficult to study using oversimplified two-dimensional (2D) cell culture systems. By contrast, three dimensional (3D) in vitro models such as spheroids, organoids, and scaffold-based constructs have been able to replicate tumors three-dimensionality and have allowed a better understanding of the role of various microenvironmental cues in the initiation and progression of cancer. However, the heterogeneity of TME cannot be fully reproduced by these traditional tissue engineering strategies since they are unable to control the organization of multiple cell types in a complex architecture. 3D bioprinting is an emerging field that can be leveraged to produce biomimetic and complex tissue structures. Bioprinting allows for controllable and precise placement of multicomponent bioinks composed of multiple biomaterials, different types of cells, and soluble factors according to the natural compartments of the target tissue, aiming to reproduce the equivalent of the complex tissue. As such, 3D bioprinting provides a unique opportunity to fabricate in vitro tumor models with a complexity similar to that of the in vivo oral carcinoma. This will facilitate a thorough investigation of cellular physiology, cancer progression, and anti-cancer drug screening with unprecedented control and reproducibility. In this review, we discuss the role of 3D bioprinting in reconstituting oral cancer, the prospects of application to fill the literature gap, and the challenges that need to be addressed in order to exploit this emerging technology for future work in oral cancer research.

The downregulation of IGFBP3 by TGF-β signaling in oral cancer contributes to the osteoclast differentiation

Oral squamous cell carcinoma (OSCC) frequently invades nearby bone and bone involvement determines the prognosis of patients. Growth factors, stored in the bone matrix and released during bone destruction, are known as key components in the bone-tumor interaction. However, the coordination of growth factor signals and the precise mechanism of bone destruction in oral cancer are still unclear. In the study, we investigated the differential cytokine expression profile of oral cancer cells by TGF-β treatment and the function of altered expression of cytokines on the osteoclast differentiation. We established TGFBR2-knockdown cells using small hairpin RNA. TGF-β was treated to both TGFBR2 expressing and knockdown cells and the culture supernatants were analyzed using a cytokine array kit. We found that the TGF-β inhibited IGFBP3 level and enhanced MMP9 level. We confirmed this regulation of IGFBP3 and MMP9 by TGF-β using ELISA and zymography, respectively. IGFBP3 is known as to modulate the bioavailability of IGF1, which is abundant in the bone microenvironment and regulates osteoclast differentiation. Therefore, we further analyzed the function of IGFBP3 on osteoclastogenesis. Although IGFBP3 increased the viability of murine bone marrow macrophages, the osteoclast differentiation of these cells was blocked by IGFBP3 in a dose-dependent manner. These results revealed a novel pathway for the regulation of osteoclastogenesis by oral cancer cells, which may be a new therapeutic target for osteolysis induced by oral cancer infiltrating into the bone.

Current Understanding of the HIF-1-Dependent Metabolism in Oral Squamous Cell Carcinoma

Oral squamous cell carcinoma (OSCC) is the 10th most frequent human malignancy and is thus a global burden. Despite some progress in diagnosis and therapy, patients' overall survival rate, between 40 and 55%, has stagnated over the last four decades. Since the tumor node metastasis (TNM) system is not precise enough to predict the disease outcome, additive factors for diagnosis, prognosis, prediction and therapy resistance are urgently needed for OSCC. One promising candidate is the hypoxia inducible factor-1 (HIF-1), which functions as an early regulator of tumor aggressiveness and is a key promoter of energy adaptation. Other parameters comprise the composition of the tumor microenvironment, which determines the availability of nutrients and oxygen. In our opinion, these general processes are linked in the pathogenesis of OSCC. Based on this assumption, the review will summarize the major features of the HIF system-induced activities, its target proteins and related pathways of nutrient utilization and metabolism that are essential for the initiation, progression and therapeutic stratification of OSCC.

CCL28-induced RARβ expression inhibits oral squamous cell carcinoma bone invasion

Oral squamous cell carcinoma (OSCC) frequently invades the maxillary or mandibular bone, and this bone invasion is closely associated with poor prognosis and survival. Here, we show that CCL28 functions as a negative regulator of OSCC bone invasion. CCL28 inhibited invasion and epithelial-mesenchymal transition (EMT), and its inhibition of EMT was characterized by induced E-cadherin expression and reduced nuclear localization of β-catenin in OSCC cells with detectable RUNX3 expression levels. CCL28 signaling via CCR10 increased retinoic acid receptor-β (RARβ) expression by reducing the interaction between RARα and HDAC1. In addition, CCL28 reduced RANKL production in OSCC and osteoblastic cells and blocked RANKL-induced osteoclastogenesis in osteoclast precursors. Intraperitoneally administered CCL28 inhibited tumor growth and osteolysis in mouse calvaria and tibia inoculated with OSCC cells. RARβ expression was also increased in tumor tissues. In patients with OSCC, low CCL28, CCR10, and RARβ expression levels were highly correlated with bone invasion. Patients with OSCC who had higher expression of CCL28, CCR10, or RARβ had significantly better overall survival. These findings suggest that CCL28, CCR10, and RARβ are useful markers for the prediction and treatment of OSCC bone invasion. Furthermore, CCL28 upregulation in OSCC cells or CCL28 treatment can be a therapeutic strategy for OSCC bone invasion.

Tumour mismatch repair protein loss is associated with advanced stage in oral cavity squamous cell carcinoma

An unexplained increase in the incidence of oral cavity squamous cell carcinoma (oSCC) has been observed despite decreasing smoking rates, particularly in younger patients. Links to defects in the DNA mismatch repair (MMR) system are well established in early onset colorectal, urothelial and gynaecological malignancies. MMR deficient patients treated with immune checkpoint inhibitors have demonstrated improved response rates. Studies exploring MMR status in head and neck squamous cell carcinoma (HNSCC) demonstrate conflicting results. This study explores the incidence of MMR protein loss and its association with clinicopathological features and outcome in oSCC. Immunohistochemical staining using tissue microarrays to assess the expression of MMR proteins (hMLH1, hMSH2, hMSH6, and hPMS2) was performed on 285 consecutive oSCC cases between 2000 and 2016. Data on smoking, alcohol and metachronous malignancies were retrospectively collected. Proportional hazards regression models were used to compare survival in MMR intact and deficient patients. MMR deficiency was seen in 21 patients (7.4%). MMR deficient tumours were associated with bone invasion (52% vs 32%, p=0.05), higher pT stage (pT4 in 57% vs 35%, p<0.001) and a higher number of metachronous malignancies (p=0.05). MMR deficiency was not associated with younger age at presentation or absence of smoking or alcohol. There was no significant association between MMR status and survival (overall survival hazard ratio 1.36; p=0.32). The incidence of MMR loss in oSCC is low and is not associated with young age at presentation. MMR deficiency in oSCC is associated with an increase in the number of metachronous malignancies and more advanced primary tumours.