1. ¹Division of Cancer Gene Regulation, Research Section of Disease Control, Institute for Genetic Medicine, Hokkaido University, Sapporo, Hokkaido, Japan
2. ²Department of Medical Oncology, Graduate School of Dental Medicine, Hokkaido University, Hokkaido, Japan
3. ³Department of Surgical Oncology, Graduate School of Dental Medicine, Hokkaido University, Hokkaido, Japan
4. ⁴Department of Obstetrics and Gynecology, Graduate School of Medicine, Graduate School of Dental Medicine, Hokkaido University, Hokkaido, Japan
5. ⁵Oral Diagnosis and Oral Medicine, Department of Oral Patho-Biological Science, Graduate School of Dental Medicine, Hokkaido University, Hokkaido, Japan
6. ⁶Department of Urology, Sapporo Medical University, Sapporo, Hokkaido, Japan

Correspondence: M Takimoto, E-mail: takimoto@med.hokudai.ac.jp.

⁷These two authors have contributed equally to this work.

Received 3 December 2001; Revised 4 March 2002; Accepted 27 March 2002.

Abstract

We found a significant correlation between lung cancer in smokers and the expression of a human gene, D40, predominantly expressed in testis and cancers. In an attempt to clone a novel human gene, we screened a cDNA library derived from a human B cell line and obtained a cDNA clone that we refer to as D40. A search for public databases for sequence homologies showed that the D40 gene is identical to AF15q14. D40 mRNA is predominantly expressed in normal testis tissue. However, this gene is also expressed in various human tumour cell lines and primary tumours derived from various organs and tissues, such as lung cancer. We examined the relationship between D40 expression and clinico-pathological characteristics of tumours in primary lung cancer. D40 expression did not significantly correlate with either histological type or pathological tumour stage. However, D40 expression was observed more frequently in poorly differentiated tumours than in well or moderately differentiated ones. Furthermore, the incidence of D40 expression was significantly higher in tumours from patients who smoke than in those from non-smokers. D40/AF15q14 is the first gene in the cancer/testis family for which expression is related to the smoking habits of cancer patients.