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Prognostic significance of p62/SQSTM1 subcellular localization and LC3B in oral squamous cell carcinoma.

Liu JL, Chen FF, Lung J, Lo CH, Lee FH, Lu YC, Hung CH - Br. J. Cancer (2014)

Bottom Line: High p62 mRNA expression was associated with high p62 protein expression in the cytoplasm.Increased LC3B punctae, high cytoplasmic p62, and low nuclear p62 expressions in OSCCs were associated with aggressive clinicopathologic features and unfavourable prognosis.Furthermore, we disclosed that high cytoplasmic p62 expression accompanied with either a low or high LC3B expression, which indicated autophagy impairment under basal or activated autophagic activity, was associated with aggressive behaviour in advanced OSCCs.

View Article: PubMed Central - PubMed

Affiliation: 1] Department of Pathology, St. Martin De Porres Hospital, No. 565, Sector 2, Daya Road, Chiayi City 600, Taiwan [2] Graduate Institute of Clinical Medical Sciences, College of Medicine, Chang Gung University, No. 259, Wenhua 1st Road, Guishan Township, Taoyuan County 333, Taiwan.

ABSTRACT

Background: Autophagy is a programmed cell survival mechanism that has a key role in both physiologic and pathologic conditions. The relationship between autophagy and cancer is complex because autophagy can act as either a tumour suppressor or as a tumour promoter. The role of autophagy in oral squamous cell carcinoma (OSCC) is controversial. Several studies have claimed that either a high or low expression of autophagy-related proteins was associated with poor prognosis of OSCCs. The aims of the study were to compare autophagy in OSCCs, verrucous hyperplasias, and normal oral mucosas, and to inspect the prognostic role of autophagy in OSCCs.

Methods: We used the autophagosome marker, LC3B, and autophagy flux marker, p62/SQSTM1 (p62), by using immunohistochemistry, and examined p62 mRNA by RNA in situ hybridization, to evaluate autophagy in 195 OSCCs, 47 verrucous hyperplasias, and 37 normal oral mucosas. The prognostic roles of LC3B and p62 protein expressions in OSCCs were investigated.

Results: We discovered that the normal oral mucosa exhibited limited LC3B punctae and weak cytoplasmic p62 staining, whereas the OSCCs exhibited a marked increase in LC3B punctae and cytoplasmic p62 expression. The expression pattern of LC3B and cytoplasmic p62 of the verrucous hyperplasias were between normal oral mucosas and OSCCs. The normal oral mucosas, verrucous hyperplasias, and OSCCs presented no differences in nuclear p62 expression and the p62 mRNA level. p62 mRNA expression was elevated in a minority of cases. High p62 mRNA expression was associated with high p62 protein expression in the cytoplasm. Increased LC3B punctae, high cytoplasmic p62, and low nuclear p62 expressions in OSCCs were associated with aggressive clinicopathologic features and unfavourable prognosis. In addition, low nuclear p62 expression was an independent prognostic factor for overall and disease-specific survival rates. Furthermore, we disclosed that high cytoplasmic p62 expression accompanied with either a low or high LC3B expression, which indicated autophagy impairment under basal or activated autophagic activity, was associated with aggressive behaviour in advanced OSCCs.

Conclusions: We suggested that autophagy was altered during cancer initiation and progression. Autophagy impairment contributed to cancer progression in advanced OSCCs.

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The results of LC3B and p62 immunohistochemical stains in normal oral mucosas, verrucous hyperplasias, and OSCCs.(A) Representative cases of LCB stainings (original magnification × 400). The normal oral mucosa shows limited LC3B punctae (intensity=0). The verrucous hyperplasia exhibits focal increased in LC3 punctae (intensity=2). The OSCCs show scanty LC3B punctae (intensity=1) and marked increased LC3B punctae with dot clusters (intensity=3). (B) Representative cases of p62 stainings (original magnification × 400). The normal oral mucosa exhibits low cytoplasmic and high nuclear p62 staining. The verrucous hyperplasia shows increased cytoplasmic p62 staining, and the dysplastic cells of basal layer shows negative nuclear staining. The OSCCs display various cytoplasmic and nuclear staining patterns. (C) Comparision of immunohistochemical Q scores of LC3B and p62 between OSCCs, verrucous hyperplasias, and normal oral mucosas. The medium lines of boxes show the median value, whereas top and bottom lines of boxes represent 75th and 25th percentiles, respectively. The ends of whiskers represent 10th and 90th percentiles. Open circles indicate the outliers.
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fig1: The results of LC3B and p62 immunohistochemical stains in normal oral mucosas, verrucous hyperplasias, and OSCCs.(A) Representative cases of LCB stainings (original magnification × 400). The normal oral mucosa shows limited LC3B punctae (intensity=0). The verrucous hyperplasia exhibits focal increased in LC3 punctae (intensity=2). The OSCCs show scanty LC3B punctae (intensity=1) and marked increased LC3B punctae with dot clusters (intensity=3). (B) Representative cases of p62 stainings (original magnification × 400). The normal oral mucosa exhibits low cytoplasmic and high nuclear p62 staining. The verrucous hyperplasia shows increased cytoplasmic p62 staining, and the dysplastic cells of basal layer shows negative nuclear staining. The OSCCs display various cytoplasmic and nuclear staining patterns. (C) Comparision of immunohistochemical Q scores of LC3B and p62 between OSCCs, verrucous hyperplasias, and normal oral mucosas. The medium lines of boxes show the median value, whereas top and bottom lines of boxes represent 75th and 25th percentiles, respectively. The ends of whiskers represent 10th and 90th percentiles. Open circles indicate the outliers.

Mentions: All of the cases exhibited cytoplasmic LC3B punctae in various proportions of the cells (Figure 1A). The normal oral mucosas exhibited limited expression of LC3B punctae. Some verrucous hyperplasias exhibited focal increase in the number of LC3B punctae. The intensity of the punctae was sometimes heterogeneous in OSCCs, even in the same specimen. A proportion of the OSCCs presented a pattern similar to that of the normal oral muocsas, and certain cases exhibited dense clusters of dots. The median Q scores of LC3B were 5, 40, and 80 for the normal oral mucosas, verrucous hyperplasias, and OSCCs, respectively (Figure 1C). The differences in Q score between the three groups were statistically significant (P<0.001).


Prognostic significance of p62/SQSTM1 subcellular localization and LC3B in oral squamous cell carcinoma.

Liu JL, Chen FF, Lung J, Lo CH, Lee FH, Lu YC, Hung CH - Br. J. Cancer (2014)

The results of LC3B and p62 immunohistochemical stains in normal oral mucosas, verrucous hyperplasias, and OSCCs.(A) Representative cases of LCB stainings (original magnification × 400). The normal oral mucosa shows limited LC3B punctae (intensity=0). The verrucous hyperplasia exhibits focal increased in LC3 punctae (intensity=2). The OSCCs show scanty LC3B punctae (intensity=1) and marked increased LC3B punctae with dot clusters (intensity=3). (B) Representative cases of p62 stainings (original magnification × 400). The normal oral mucosa exhibits low cytoplasmic and high nuclear p62 staining. The verrucous hyperplasia shows increased cytoplasmic p62 staining, and the dysplastic cells of basal layer shows negative nuclear staining. The OSCCs display various cytoplasmic and nuclear staining patterns. (C) Comparision of immunohistochemical Q scores of LC3B and p62 between OSCCs, verrucous hyperplasias, and normal oral mucosas. The medium lines of boxes show the median value, whereas top and bottom lines of boxes represent 75th and 25th percentiles, respectively. The ends of whiskers represent 10th and 90th percentiles. Open circles indicate the outliers.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4150268&req=5

fig1: The results of LC3B and p62 immunohistochemical stains in normal oral mucosas, verrucous hyperplasias, and OSCCs.(A) Representative cases of LCB stainings (original magnification × 400). The normal oral mucosa shows limited LC3B punctae (intensity=0). The verrucous hyperplasia exhibits focal increased in LC3 punctae (intensity=2). The OSCCs show scanty LC3B punctae (intensity=1) and marked increased LC3B punctae with dot clusters (intensity=3). (B) Representative cases of p62 stainings (original magnification × 400). The normal oral mucosa exhibits low cytoplasmic and high nuclear p62 staining. The verrucous hyperplasia shows increased cytoplasmic p62 staining, and the dysplastic cells of basal layer shows negative nuclear staining. The OSCCs display various cytoplasmic and nuclear staining patterns. (C) Comparision of immunohistochemical Q scores of LC3B and p62 between OSCCs, verrucous hyperplasias, and normal oral mucosas. The medium lines of boxes show the median value, whereas top and bottom lines of boxes represent 75th and 25th percentiles, respectively. The ends of whiskers represent 10th and 90th percentiles. Open circles indicate the outliers.
Mentions: All of the cases exhibited cytoplasmic LC3B punctae in various proportions of the cells (Figure 1A). The normal oral mucosas exhibited limited expression of LC3B punctae. Some verrucous hyperplasias exhibited focal increase in the number of LC3B punctae. The intensity of the punctae was sometimes heterogeneous in OSCCs, even in the same specimen. A proportion of the OSCCs presented a pattern similar to that of the normal oral muocsas, and certain cases exhibited dense clusters of dots. The median Q scores of LC3B were 5, 40, and 80 for the normal oral mucosas, verrucous hyperplasias, and OSCCs, respectively (Figure 1C). The differences in Q score between the three groups were statistically significant (P<0.001).

Bottom Line: High p62 mRNA expression was associated with high p62 protein expression in the cytoplasm.Increased LC3B punctae, high cytoplasmic p62, and low nuclear p62 expressions in OSCCs were associated with aggressive clinicopathologic features and unfavourable prognosis.Furthermore, we disclosed that high cytoplasmic p62 expression accompanied with either a low or high LC3B expression, which indicated autophagy impairment under basal or activated autophagic activity, was associated with aggressive behaviour in advanced OSCCs.

View Article: PubMed Central - PubMed

Affiliation: 1] Department of Pathology, St. Martin De Porres Hospital, No. 565, Sector 2, Daya Road, Chiayi City 600, Taiwan [2] Graduate Institute of Clinical Medical Sciences, College of Medicine, Chang Gung University, No. 259, Wenhua 1st Road, Guishan Township, Taoyuan County 333, Taiwan.

ABSTRACT

Background: Autophagy is a programmed cell survival mechanism that has a key role in both physiologic and pathologic conditions. The relationship between autophagy and cancer is complex because autophagy can act as either a tumour suppressor or as a tumour promoter. The role of autophagy in oral squamous cell carcinoma (OSCC) is controversial. Several studies have claimed that either a high or low expression of autophagy-related proteins was associated with poor prognosis of OSCCs. The aims of the study were to compare autophagy in OSCCs, verrucous hyperplasias, and normal oral mucosas, and to inspect the prognostic role of autophagy in OSCCs.

Methods: We used the autophagosome marker, LC3B, and autophagy flux marker, p62/SQSTM1 (p62), by using immunohistochemistry, and examined p62 mRNA by RNA in situ hybridization, to evaluate autophagy in 195 OSCCs, 47 verrucous hyperplasias, and 37 normal oral mucosas. The prognostic roles of LC3B and p62 protein expressions in OSCCs were investigated.

Results: We discovered that the normal oral mucosa exhibited limited LC3B punctae and weak cytoplasmic p62 staining, whereas the OSCCs exhibited a marked increase in LC3B punctae and cytoplasmic p62 expression. The expression pattern of LC3B and cytoplasmic p62 of the verrucous hyperplasias were between normal oral mucosas and OSCCs. The normal oral mucosas, verrucous hyperplasias, and OSCCs presented no differences in nuclear p62 expression and the p62 mRNA level. p62 mRNA expression was elevated in a minority of cases. High p62 mRNA expression was associated with high p62 protein expression in the cytoplasm. Increased LC3B punctae, high cytoplasmic p62, and low nuclear p62 expressions in OSCCs were associated with aggressive clinicopathologic features and unfavourable prognosis. In addition, low nuclear p62 expression was an independent prognostic factor for overall and disease-specific survival rates. Furthermore, we disclosed that high cytoplasmic p62 expression accompanied with either a low or high LC3B expression, which indicated autophagy impairment under basal or activated autophagic activity, was associated with aggressive behaviour in advanced OSCCs.

Conclusions: We suggested that autophagy was altered during cancer initiation and progression. Autophagy impairment contributed to cancer progression in advanced OSCCs.

Show MeSH
Related in: MedlinePlus