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Pathology International 2015; 65: 460–467
doi:10.1111/pin.12323
Original Article
L-type amino acid transporter-1 and CD98 expression in bone and soft tissue tumors
Hiromi Koshi,1,2 Takaaki Sano,1 Tadashi Handa,1 Takashi Yanagawa,2 Kenichi Saitou,2 Shushi Nagamori,3 Yoshikatsu Kanai,3 Kenji Takagishi2 and Tetsunari Oyama1 Departments of 1Diagnostic Pathology and 2Orthopedic Surgery, Gunma University Graduate School of Medicine, Maebashi and 3Department of Pharmacology, Osaka University Graduate School of Medicine, Osaka, Japan
L-type amino acid transporter-1 (LAT1) is expressed in many cancers. We examined LAT1 and CD98 expression immunohistochemically in surgically resected specimens of various bone and soft tissue tumors. Out of 226 cases, 79 (35%) were LAT1+ and 95 (42%) were CD98+. In bone tumors, LAT1 was highly expressed in osteoblastoma (89%), chondrosarcoma (50%), and osteosarcoma (60%); in soft tissue tumors, LAT1 was highly expressed in rhabdomyosarcoma (80%), synovial sarcoma (63%), Ewing’s sarcoma (60%), epithelioid sarcoma (100%) and angiosarcoma (100%). In malignant soft tissue tumors, LAT1 expression was associated with higher histological grade. High CD98 expression was seen in many bone tumors of intermediate and high malignancy. Among soft tissue tumors, CD98 was expressed in tendon sheath giant cell tumor and malignant peripheral nerve sheath tumor (57%), Ewing’s sarcoma (50%) and undifferentiated sarcoma (64%). Some of the malignant soft tissue tumors expressed both LAT1 and CD98. This study showed that LAT1 and CD98 was expressed in many malignant and intermediate bone tumors, and some malignant soft tissue tumors. Key words: bone tumors, CD98, L-type amino transporter-1, immunohistochemistry, soft tissue tumors
acid
Amino acid transporters are essential for normal cell growth and proliferation. In mammals, about 50 types of these transporters are known. L-type amino acid transporter-1 (LAT1) is an L-type amino-acid transporter that transports large neutral amino acids, such as leucine, isoleucine, valine, phenylalanine, tyrosine, tryptophan, methionine and histidine.1 In normal tissue, LAT1 is normally expressed in fetal liver, bone
Correspondence: Hiromi Koshi, MD, Department of Diagnostic Pathology, Gunma University Graduate School of Medicine, 3-39-22 Showa-machi, Maebashi, Gunma 371-8511, Japan. Email: [email protected] Received 30 January 2015. Accepted for publication 1 June 2015. © 2015 Japanese Society of Pathology and Wiley Publishing Asia Pty Ltd
marrow, placenta, testes and brain,2 but is reported to be highly expressed in many malignant tumors, and to affect cell proliferation, angiogenesis and the cell cycle.3 We have researched the relationships between LAT1 and histopathological factor in several cancers, including lung, breast and prostate cancers.4–9 CD98 (4F2hc) is an integral membrane protein with a singlemembrane spanning domain, classified as a type II membrane glycoprotein. LAT1 and CD98 link to each other via a disulfide bond. They are reportedly both overexpressed on tumor cell membranes, to function together as a Na+-independent neural amino acid transporter.1,2,10 Several studies have shown LAT1 expression or LAT1 + CD98 expression to be potential prognostic factors for human neoplasms.4–9,11–13 In non-small-cell lung carcinoma, overexpression of LAT1 and CD98 independently predicts poor prognosis for patients with resectable stage I pulmonary adenocarcinoma.5 In prostate cancer, immunoreactive LAT1 expression and Gleason score were strongly and significantly correlated.9 In breast cancer, LAT1 and CD98 expression correlated with tumor size, nuclear grade and Ki-67 labeling index (LI).7 Some compounds reportedly inhibit LAT1; 2-aminobicyclo(2,2,1)-heptane-2-carboxylic acid (BCH) suppresses cancer cell growth, inducing apoptosis by intracellular depletion of the neutral amino acids needed for cancer cell growth.14 KYT-0353, a novel tyrosine analog with high LAT1 selectivity and potent in vitro and in vivo inhibitory activity,15 inhibits 14C-leucine uptake and cell growth in human colon cancerderived HT-29 cells. These inhibitors may help treat many malignant tumors that express LAT1. Additionally, L-[3-18F]α–methyltyrosine (18F-FAMT), as an amino acid tracer for PET imaging, provides better specificity than 18F-FDG PET for cancer diagnosis,16 as it accumulates in tumor cells via LAT1.17 18F-FAMT PET has been shown clinically to differentiate between malignant tumors and benign lesions, including brain tumors, oral squamous cell carcinoma, and bone and soft tissue tumors.18–20
LAT1 in bone and soft tissue tumors
Only one study about LAT1 and CD98 expression in bone and soft tissue tumors has been reported; it examined and compared expression and function of L-type amino acid transporters in both immortalized fetal osteoblast cells (FOB) and Saos2 human osteogenic sarcoma cells.21 Transport of neutral amino acids into the FOB and Saos2 cells are mainly mediated by L-type amino acid transporter 2 (which is expressed in normal tissue) and LAT1, respectively. To our knowledge, no study has used immunohistochemistry (IHC) with clinical specimens of various bone and soft tissue tumors associated with LAT1 and CD98 expression. In the present study, we examined the association of LAT1 and CD98 expression with the histopathological features of various bone and soft tissue tumors, and their Ki-67 LIs.
specimens came from surgical resections or biopsies performed at Gunma University Hospital between 2000 and 2014. Among them, 47 specimens were obtained through biopsy, comprising 25 osteosarcoma, 4 osteoblastoma, 4 chondrosarcoma, 10 Ewing’s sarcoma, 1 epithelioid sarcoma, and 3 angiosarcomas. The remaining 179 specimens were taken by resection. No patient received chemotherapy before the resection or biopsy. Pathological diagnosis of all specimens was reviewed by three pathologists (HK, TS and TO). All bone and soft tissue tumor samples were generally classified by the World Health Organization (WHO) tumor classification22 (Table 1). The tumor subtypes included 3 benign bone tumor types (enchondroma, chondroblastoma and osteoblastoma), 1 bone tumor of intermediate malignancy (giant cell tumor), 2 malignant bone tumor types (chondrosarcoma and osteosarcoma), 6 benign soft tissue tumor types (lipoma, leiomyoma, hemangioma, dermatofibroma, nodular fasciitis and giant cell tumor of the tendon sheath), and 12 malignant soft tissue tumor types (well-differentiated liposarcoma, dedifferentiated liposarcoma, dermatofibrosarcoma protuberans, myxofibrosarcoma, leiomyosarcoma, rhabdomyosarcoma, malignant
MATERIALS AND METHODS Clinical samples All 226 formalin-fixed, paraffin-embedded bone and soft tissue tumors (76 bone tumors and 150 soft tissue tumors)
Table 1
461
Summary of immunohistochemistry for LAT1 and CD98 in bone and soft tissue tumors LAT1 scores
Bone tumors
Soft tissue tumors
All
CD98 scores
Diagnosis
N
0
1
2
3
4
+ (%)
0
1
2
3
4
+ (%)
P
Enchondroma Chondroblastoma Osteoblastoma Giant cell tumor Chondrosarcoma Osteosarcoma Total Lipoma Leiomyoma Hemangioma Dermatofibroma Nodular fasciitis Giant cell tumor of the tendon sheath Well differentiated liposarcoma Dedifferentiated liposarcoma Dermatofibrosarcoma protuberans Myxofibrosarcoma Leiomyosarcoma Rhabdomyosarcoma Malignant peripheral nerve sheath tumor Synovial sarcoma Ewing’s sarcoma Epithelioid sarcoma Angiosarcoma Undifferentiated sarcoma Total Total
11 5 9 12 14 25 76 7 9 5 6 7 9
11 2 0 4 6 5 28 7 9 4 6 7 3
0 1 1 4 1 5 12 0 0 1 0 0 6
0 1 3 4 1 9 18 0 0 0 0 0 0
0 1 1 0 3 5 10 0 0 0 0 0 0
0 0 4 0 3 1 8 0 0 0 0 0 0
0 (0) 2 (40) 8 (89) 4 (33) 7 (50) 15 (60) 36 (47) 0 (0) 0 (0) 0 (0) 0 (0) 0 (0) 0 (0)
11 0 0 0 10 0 21 3 8 5 3 5 1
0 0 1 0 1 2 4 4 1 0 3 1 3
0 4 2 7 2 3 18 0 0 0 0 1 5
0 1 0 4 1 3 9 0 0 0 0 0 0
0 0 6 1 0 17 24 0 0 0 0 0 0
0 (0) 5 (100) 8 (89) 12 (100) 3 (21) 23 (92) 52 (67) 0 (0) 0 (0) 0 (0) 0 (0) 1 (14) 5 (55)
NS NS 0.708 NS 0.515 0.071
Pathology International 2015; 65: 460–467
doi:10.1111/pin.12323
Original Article
L-type amino acid transporter-1 and CD98 expression in bone and soft tissue tumors
Hiromi Koshi,1,2 Takaaki Sano,1 Tadashi Handa,1 Takashi Yanagawa,2 Kenichi Saitou,2 Shushi Nagamori,3 Yoshikatsu Kanai,3 Kenji Takagishi2 and Tetsunari Oyama1 Departments of 1Diagnostic Pathology and 2Orthopedic Surgery, Gunma University Graduate School of Medicine, Maebashi and 3Department of Pharmacology, Osaka University Graduate School of Medicine, Osaka, Japan
L-type amino acid transporter-1 (LAT1) is expressed in many cancers. We examined LAT1 and CD98 expression immunohistochemically in surgically resected specimens of various bone and soft tissue tumors. Out of 226 cases, 79 (35%) were LAT1+ and 95 (42%) were CD98+. In bone tumors, LAT1 was highly expressed in osteoblastoma (89%), chondrosarcoma (50%), and osteosarcoma (60%); in soft tissue tumors, LAT1 was highly expressed in rhabdomyosarcoma (80%), synovial sarcoma (63%), Ewing’s sarcoma (60%), epithelioid sarcoma (100%) and angiosarcoma (100%). In malignant soft tissue tumors, LAT1 expression was associated with higher histological grade. High CD98 expression was seen in many bone tumors of intermediate and high malignancy. Among soft tissue tumors, CD98 was expressed in tendon sheath giant cell tumor and malignant peripheral nerve sheath tumor (57%), Ewing’s sarcoma (50%) and undifferentiated sarcoma (64%). Some of the malignant soft tissue tumors expressed both LAT1 and CD98. This study showed that LAT1 and CD98 was expressed in many malignant and intermediate bone tumors, and some malignant soft tissue tumors. Key words: bone tumors, CD98, L-type amino transporter-1, immunohistochemistry, soft tissue tumors
acid
Amino acid transporters are essential for normal cell growth and proliferation. In mammals, about 50 types of these transporters are known. L-type amino acid transporter-1 (LAT1) is an L-type amino-acid transporter that transports large neutral amino acids, such as leucine, isoleucine, valine, phenylalanine, tyrosine, tryptophan, methionine and histidine.1 In normal tissue, LAT1 is normally expressed in fetal liver, bone
Correspondence: Hiromi Koshi, MD, Department of Diagnostic Pathology, Gunma University Graduate School of Medicine, 3-39-22 Showa-machi, Maebashi, Gunma 371-8511, Japan. Email: [email protected] Received 30 January 2015. Accepted for publication 1 June 2015. © 2015 Japanese Society of Pathology and Wiley Publishing Asia Pty Ltd
marrow, placenta, testes and brain,2 but is reported to be highly expressed in many malignant tumors, and to affect cell proliferation, angiogenesis and the cell cycle.3 We have researched the relationships between LAT1 and histopathological factor in several cancers, including lung, breast and prostate cancers.4–9 CD98 (4F2hc) is an integral membrane protein with a singlemembrane spanning domain, classified as a type II membrane glycoprotein. LAT1 and CD98 link to each other via a disulfide bond. They are reportedly both overexpressed on tumor cell membranes, to function together as a Na+-independent neural amino acid transporter.1,2,10 Several studies have shown LAT1 expression or LAT1 + CD98 expression to be potential prognostic factors for human neoplasms.4–9,11–13 In non-small-cell lung carcinoma, overexpression of LAT1 and CD98 independently predicts poor prognosis for patients with resectable stage I pulmonary adenocarcinoma.5 In prostate cancer, immunoreactive LAT1 expression and Gleason score were strongly and significantly correlated.9 In breast cancer, LAT1 and CD98 expression correlated with tumor size, nuclear grade and Ki-67 labeling index (LI).7 Some compounds reportedly inhibit LAT1; 2-aminobicyclo(2,2,1)-heptane-2-carboxylic acid (BCH) suppresses cancer cell growth, inducing apoptosis by intracellular depletion of the neutral amino acids needed for cancer cell growth.14 KYT-0353, a novel tyrosine analog with high LAT1 selectivity and potent in vitro and in vivo inhibitory activity,15 inhibits 14C-leucine uptake and cell growth in human colon cancerderived HT-29 cells. These inhibitors may help treat many malignant tumors that express LAT1. Additionally, L-[3-18F]α–methyltyrosine (18F-FAMT), as an amino acid tracer for PET imaging, provides better specificity than 18F-FDG PET for cancer diagnosis,16 as it accumulates in tumor cells via LAT1.17 18F-FAMT PET has been shown clinically to differentiate between malignant tumors and benign lesions, including brain tumors, oral squamous cell carcinoma, and bone and soft tissue tumors.18–20
LAT1 in bone and soft tissue tumors
Only one study about LAT1 and CD98 expression in bone and soft tissue tumors has been reported; it examined and compared expression and function of L-type amino acid transporters in both immortalized fetal osteoblast cells (FOB) and Saos2 human osteogenic sarcoma cells.21 Transport of neutral amino acids into the FOB and Saos2 cells are mainly mediated by L-type amino acid transporter 2 (which is expressed in normal tissue) and LAT1, respectively. To our knowledge, no study has used immunohistochemistry (IHC) with clinical specimens of various bone and soft tissue tumors associated with LAT1 and CD98 expression. In the present study, we examined the association of LAT1 and CD98 expression with the histopathological features of various bone and soft tissue tumors, and their Ki-67 LIs.
specimens came from surgical resections or biopsies performed at Gunma University Hospital between 2000 and 2014. Among them, 47 specimens were obtained through biopsy, comprising 25 osteosarcoma, 4 osteoblastoma, 4 chondrosarcoma, 10 Ewing’s sarcoma, 1 epithelioid sarcoma, and 3 angiosarcomas. The remaining 179 specimens were taken by resection. No patient received chemotherapy before the resection or biopsy. Pathological diagnosis of all specimens was reviewed by three pathologists (HK, TS and TO). All bone and soft tissue tumor samples were generally classified by the World Health Organization (WHO) tumor classification22 (Table 1). The tumor subtypes included 3 benign bone tumor types (enchondroma, chondroblastoma and osteoblastoma), 1 bone tumor of intermediate malignancy (giant cell tumor), 2 malignant bone tumor types (chondrosarcoma and osteosarcoma), 6 benign soft tissue tumor types (lipoma, leiomyoma, hemangioma, dermatofibroma, nodular fasciitis and giant cell tumor of the tendon sheath), and 12 malignant soft tissue tumor types (well-differentiated liposarcoma, dedifferentiated liposarcoma, dermatofibrosarcoma protuberans, myxofibrosarcoma, leiomyosarcoma, rhabdomyosarcoma, malignant
MATERIALS AND METHODS Clinical samples All 226 formalin-fixed, paraffin-embedded bone and soft tissue tumors (76 bone tumors and 150 soft tissue tumors)
Table 1
461
Summary of immunohistochemistry for LAT1 and CD98 in bone and soft tissue tumors LAT1 scores
Bone tumors
Soft tissue tumors
All
CD98 scores
Diagnosis
N
0
1
2
3
4
+ (%)
0
1
2
3
4
+ (%)
P
Enchondroma Chondroblastoma Osteoblastoma Giant cell tumor Chondrosarcoma Osteosarcoma Total Lipoma Leiomyoma Hemangioma Dermatofibroma Nodular fasciitis Giant cell tumor of the tendon sheath Well differentiated liposarcoma Dedifferentiated liposarcoma Dermatofibrosarcoma protuberans Myxofibrosarcoma Leiomyosarcoma Rhabdomyosarcoma Malignant peripheral nerve sheath tumor Synovial sarcoma Ewing’s sarcoma Epithelioid sarcoma Angiosarcoma Undifferentiated sarcoma Total Total
11 5 9 12 14 25 76 7 9 5 6 7 9
11 2 0 4 6 5 28 7 9 4 6 7 3
0 1 1 4 1 5 12 0 0 1 0 0 6
0 1 3 4 1 9 18 0 0 0 0 0 0
0 1 1 0 3 5 10 0 0 0 0 0 0
0 0 4 0 3 1 8 0 0 0 0 0 0
0 (0) 2 (40) 8 (89) 4 (33) 7 (50) 15 (60) 36 (47) 0 (0) 0 (0) 0 (0) 0 (0) 0 (0) 0 (0)
11 0 0 0 10 0 21 3 8 5 3 5 1
0 0 1 0 1 2 4 4 1 0 3 1 3
0 4 2 7 2 3 18 0 0 0 0 1 5
0 1 0 4 1 3 9 0 0 0 0 0 0
0 0 6 1 0 17 24 0 0 0 0 0 0
0 (0) 5 (100) 8 (89) 12 (100) 3 (21) 23 (92) 52 (67) 0 (0) 0 (0) 0 (0) 0 (0) 1 (14) 5 (55)
NS NS 0.708 NS 0.515 0.071
