Recurrence of squamous cell lung carcinoma is associated with the co-presence of reactive lesions in tumor-adjacent bronchial epithelium

Whole-exome sequencing reveals an association of rs112065068 in TGOLN2 gene with distant metastasis of non-small cell lung cancer

Early prediction and prevention of recurring illness is critical for improving the survival rates of patients with non-small cell lung cancer (NSCLC). Previously, we demonstrated that the presence of premalignant epithelial changes in the small bronchi distant to the primary tumor is associated with NSCLC progression: isolated basal cell hyperplasia (iBCH) indicates a high risk of distant metastasis, BCH combined with squamous metaplasia (BCHSM) - a high risk of locoregional recurrence. Here, we aimed to identify germline single nucleotide variants (SNVs) and insertions and deletions (InDels) associated with distant metastasis and locoregional recurrence in cases with iBCH and BCHSM using whole-exome sequencing of 172 NSCLC patients. The rs112065068 of the TGOLN2 gene was identified only in iBCH patients and was associated with a high risk of distant metastasis (P < .001) and worse metastasis-free survival (HR = 4.19 (95 %CI 1.97-8.93); P < .001). This variant was validated in a group of 109 NSCLC patients using real-time PCR and Sanger sequencing analyses. To our knowledge, this study is the first to identify a germline variant associated with NSCLC distant metastasis.

Analysis of Methylome of Different Forms of Basal Cell Hyperplasia and Squamous Cell Metaplasia of Bronchial Epithelium

Squamous cell lung cancer (SCLC) occurs as a result of dysregenerative changes in the bronchial epithelium: basal cell hyperplasia (BCH), squamous cell metaplasia (SM), and dysplasia. We previously suggested that combinations of precancerous changes detected in the small bronchi of patients with SCLC may reflect various "scenarios" of the precancerous process: isolated BCH→stopping at the stage of hyperplasia, BCH+SM→progression of hyperplasia into metaplasia, SM+dysplasia→progression of metaplasia into dysplasia. In this study, DNA methylome of various forms of precancerous changes in the bronchial epithelium of SCLC patients was analyzed using the genome-wide bisulfite sequencing. In BCH combined with SM, in contrast to isolated BCH, differentially methylated regions were identified in genes of the pathogenetically significant MET signaling pathway (RNMT, HPN). Differentially methylated regions affecting genes involved in inflammation regulation (IL-23, IL-23R, IL12B, IL12RB1, and FIS1) were detected in SM combined with dysplasia in comparison with SM combined with BCH. The revealed changes in DNA methylation may underlie various "scenarios" of the precancerous process in the bronchial epithelium.

DNA methylome analysis reveals potential alterations contributing to the progression of bronchial hyperplasia

BACKGROUND

Squamous cell lung cancer (SCLC) arises from bronchial changes: basal cell hyperplasia (BCH), squamous metaplasia (SM), and dysplasia. However, the premalignant process preceding SCLC is not inevitable; it can stop at any of the bronchial lesions. Previously, we hypothesized that combinations of premalignant lesions observed in the small bronchi of SCLC patients can reflect the different "scenarios" of the premalignant process: BCHi-the stoppage at the stage of hyperplasia and BCHSM-the progression of hyperplasia to metaplasia.

METHODS AND RESULTS

In this study, using whole-genome bisulfite sequencing we analyzed the DNA methylome of two forms of BCH: isolated BCH (BCHi) and BCH co-occurred with SM (BCHSM) in the small bronchi of SCLC patients. It was shown that BCHi harbored differentially methylated regions (DMRs) affecting genes associated with regulating phosphatase activity. In BCHSM, DMRs were found in genes involved in PI3K-Akt and AMPK signaling pathways. DMRs were also found to affect specific miRNA genes: miR-34a and miR-3648 in BCHi and miR-924 and miR-100 in BCHSM.

CONCLUSIONS

Thus, this study demonstrated the significant changes in DNA methylome between the isolated BCH and BCH combined with SM. The identified epigenetic alterations may underlie different "scenarios" of the premalignant process in the bronchial epithelium.

Clinical and morphological features of non-small cell lung cancer in patients with different types of histological changes to the bronchial epithelium

Lung cancer occupies the leading position in the global structure of oncological diseases. Despite significant advances in its treatment, the survival remains low. Morphological changes to the bronchial epithelium outside the tumor may provide important cues on progression of the disease in patients with lung cancer. This study aimed to identify associations between morphological and clinical features of non-small cell lung cancer and morphological changes to the epithelium in small bronchi outside the tumor. The study encompassed tumor specimens collected from 90 patients, 75 (83%) men and 15 (17%) women, diagnosed with non-small cell lung cancer. The average age of the patients was 67.8 ± 7.4 years. The results indicate higher frequency of lymphogenous metastasis in patients with combined basal cell hyperplasia and squamous metaplasia (BCH+SM+ group) compared to patients with isolated basal cell hyperplasia (BCH+SM– group, p = 0.05). The BCH+SM– group presented with higher rates of hematogenous metastasis compared to BCH+SM+ and BCH–SM– groups (p = 0.004 and p = 0.0019, respectively), as well as increased representation of low-differentiated structures in the primary tumors. The results suggest a commonality of parenchymal-stromal interactions in non-small cell lung cancers and their surroundings and a significant impact of these interactions on differentiation status and progression of the tumors.

Premalignant Changes in the Bronchial Epithelium Are Prognostic Factors of Distant Metastasis in Non-Small Cell Lung Cancer Patients

Background

The study assessed the possibility of dividing patients into groups based on the assessment of morphological changes in the epithelium of small-caliber bronchi located near the primary tumor in order to predict high and low risks of distant metastasis of non-small cell lung cancer.

Methods

In 171 patients with non-small cell lung cancer (T_1-4N_0-3M₀) in small-caliber bronchi taken at a distance of 3–5 cm from the tumor, various variants of morphological changes in the bronchial epithelium (basal cell hyperplasia (BCH), squamous cell metaplasia (SM), and dysplasia (D)) were assessed. Long-term results of treatment, namely, distant metastasis, were assessed after 2 and 5 years.

Results

During the follow-up period, distant metastases were found in 35.1% (60/171) of patients. Most often, they were observed in patients of the high-risk group: BCH+SM−D− (51.6%, 40/95) and BCH−SM+D+ (54.4%, 6/11). Less often, distant metastases were observed in low-risk group patients: BCH+SM+D− (6.7%, 3/45) and BCH−SM−D− (10.0%, 2/20). Tumor size, grade, and stage were significant predictors of metastasis only in the high-risk group. The 5-year metastasis-free survival was better in the low-risk group of distant metastases.

Conclusions

Isolated BCH or dysplasia in small bronchi distant from foci of tumor is associated with a high-risk distant metastasis and less 5-year metastasis-free survival.

Neoadjuvant chemotherapy combined with intraoperative radiotherapy is effective to prevent recurrence in high-risk non-small cell lung cancer (NSCLC) patients

Background

Basal cell hyperplasia (BCH) and squamous metaplasia (SM) in the small bronchi distant from the tumor is associated with a high risk of non-small cell lung cancer (NSCLC) recurrence. Here, we assessed whether neoadjuvant chemotherapy (NAC), intraoperative radiotherapy (IORT), or adjuvant chemotherapy (AC) is effective to prevent recurrence in NSCLC patients (n=171) with different premalignant lesions in the small bronchi

Methods

BCH, SM, and dysplasia (D) were identified in the samples of lung tissue distant from the tumor. NSCLC patients were treated by surgery, different combinations of NAC and IORT, and AC.

Results

Based on the type of bronchial lesions, NSCLC patients were classified into four groups: BCH⁺SM⁻D⁻ (55.6%, 95/171), BCH⁺SM⁺D⁻ (26.3%; 45/171), BCH⁻SM⁺D⁺ (6.4%, 11/171), and BCH⁻SM⁻D⁻ (11.7%, 20/171). During 5 years, recurrent carcinoma was found in 13.4% (23/171) of patients and represented by metachronous metastases in the thoracic lymph nodes (82.6%, 19/23) and by a relapse in the bronchial stump (17.4%, 4/23). Recurrence was frequent in BCH⁺SM⁺D⁻ patients (87.0%, 20/23), rare in BCH⁺SM⁻D⁻ and BCH⁻SM⁻D⁻ patients (13.0%, 3/23), and absent in BCH⁻SM⁺D⁺ patients (0/23). The 5-year recurrence-free survival was also shorter in BCH⁺SM⁺D⁻ patients (HR 27.35; 95% CI: 6.31−118.48; P<0.0001). In the high-risk (BCH⁺SM⁺D⁻) group, recurrence occurred mainly in cases without NAC and IORT (88.2%, 15/17) and was absent (0/15) when these therapies were combined. NAC- and IORT-negative patients also showed poor overall survival (HR 4.35; 95% CI: 1.96−9.66; P<0.0001) and tended to have decreased recurrence-free survival (P=0.075). Importantly, the recurrence rate was not different between AC-treated and AC-naïve BCH⁺SM⁺D⁻ patients.

Conclusions

The combination of NAC and IORT is an effective strategy to prevent recurrence in high-risk NSCLC patients.

Premalignant lesions of squamous cell carcinoma of the lung: The molecular make-up and factors affecting their progression

Squamous cell carcinoma (SCC), one of the most common forms of lung cancer, shows accelerated progression and aggressive growth and usually is observed at advanced stages. SCC originates from morphological changes in the bronchial epithelium that occur during chronic inflammation: basal cell hyperplasia, squamous metaplasia, and dysplasia I-III. However, the process is not inevitable; it can be stopped at any stage, remain in the stable state indefinitely and either progress or regress. The reasons and mechanisms of different scenarios of the evolution of premalignant lesions in the respiratory epithelium are not fully understood. In this review, we summarized the literature data (including our own data) regarding genetic, epigenetic, transcriptomic and proteomic profiles of the premalignant lesions and highlighted factors (environmental causes, inflammation, and gene polymorphism) that may govern their progression or regression. In conclusion, we reviewed strategies for lung cancer prevention and proposed new models and research directions for studying premalignant lesions and developing new tools to predict the risk of their malignant transformation.