人体某些器官会“呼唤”癌细胞

    研究人员发现，淋巴结和肺脏等特定机体组织所释放的某些因子扮演着趋化癌细胞的作用，可“呼唤”癌细胞迁移到这些组织。

    癌细胞从原发肿瘤部位的扩散称之为转移，它是癌症病人的头号杀手。研究员发现，在小鼠中阻断那些结合了化学趋化物的受体可以阻止癌扩散。据发表在三月份的《自然》杂志的文章报导：研究者研究的是乳腺癌细胞，其发现可能对其它类型的癌细胞也适用。

    研究员认为，阻断癌细胞受体的制剂“确实具有成为抗癌细胞转移药的可能，但这种可能性在人类还有待证实”。即使这些目标能够实现，适用于这类药物治疗的人群可能只能局限于那些已经接受外科手术切除了肿瘤的病人，目的是防止癌细胞从残存的部位转移。目前尚不清楚这种治疗是否适用于癌细胞已经转移到身体其它部位的病人。

    在这项研究中，研究小组观察了一种叫做化学肽的化学信使和细胞受体之间的关系。这种锁与钥匙的关系在维持机体的正常功能方面发挥了重要作用。例如，趋化白细胞到皮肤损伤部位发挥抗感染作用。结果发现，乳腺癌细胞携带2种这样的受体(命名为CXCR4和CCR7)，其数量远比正常乳腺组织高。而且，趋化这些受体的化学肽(称为CXCL12和CCL21)通常存在于淋巴结、肺、肝和骨髓，这些正是乳腺癌最常转移的部位。报告显示：研究人员使用能够阻断CXCR4受体的化合物治疗小鼠，使乳腺癌细胞向肺的扩散减少了73%，并且减少了癌细胞扩散到淋巴结。

    该研究结果提示，肿瘤细胞使用某些信号来“确定”他们扩散的目的地，这助于解释为什么不同的癌症转移表现不同的器官特异性特点。

    Certain Organs ‘Call‘ to Cancer Cells
    NEW YORK (Reuters Health) - Researchers have discovered that certain body tissues--such as the lymph nodes and lungs--release factors that act as a siren‘s song to cancer cells, encouraging the abnormal cells to migrate and take hold in those tissues.

    What‘s more--at least in mice--investigators have found that blocking the receptors that bind to those chemical attractors can halt the spread of cancer. The spread of cancer cells from the original tumor site is known as metastasis, and it is the number one killer of cancer patients.

    Although the researchers studied breast cancer cells, they note that their findings may be true for other types of cancer as well, according to a report in the March issue of the journal Nature.

    Although the research may one day lead to treatments in human cancer patients, studies in mice do not always translate to humans.

    Agents that block the cancer cell receptors ``do indeed have potential as anti-metastatic drugs but such potential remains to be demonstrated in humans,‘‘ according to study co-author Dr. Albert Zlotnik from DNAX Research Institute in Palo Alto, California. ``However, even if these were to materialize, the target group that may benefit from such drugs may be those patients that have just undergone surgery for tumor removal in order to prevent metastases from establishing ‘beachheads,‘‘‘ he told Reuters Health. It is not clear if such treatments would help patients whose cancer has already metastasized to other parts of the body.

    In the study, Zlotnik and colleagues looked at the relationship between chemical messengers--called chemokines--and receptors on cells that bind to the chemokines. This lock-and-key relationship plays an important role in the body‘s normal functioning--for instance, calling white blood cells to fight infection in a skin wound.

    The team found that breast cancer cells carried two such receptors (named CXCR4 and CCR7) in numbers far higher than those seen in normal breast tissue.

    Moreover, the chemokines that attract these receptors--known as CXCL12 and CCL21--were most commonly produced in lymph nodes, lung, liver and bone marrow--sites where breast cancer most commonly metastasizes. The researchers found that treating mice with a compound that blocks the CXCR4 receptor reduced the spread of breast cancer cells to the lungs by as much as 73% and decreased their spread to lymph nodes, the report indicates.

    ``Our findings imply that there are signals that tumor cells use in order to ‘define‘ their metastatic destination,‘‘ Zlotnik, now at Eos Biotechnology in South San Francisco, California, told Reuters Health. ``Our findings help explain the organ-specific nature of metastasis exhibited by various cancers.